A Proposal For
VERTICAL TO HORIZONTAL TRANSITION SYSTEM
FOR
UNITED STATES NAVY CARGO/ORDNANCE ELEVATOR
By
Daniel Ballister
Ben Campanella Jr. – Team Leader
Brian Griffin
Timothy Troy
Submitted to
Department of Mechanical Engineering
Villanova University
25 November 2003
Table of Contents
1
2
INTRODUCTION ...................................................................................................... 3
BACKGROUND INFORMATION AND STATE-OF-THE-ART ........................... 4
2.1
BACKGROUND INFORMATION ................................................................... 4
2.2
DESIGN REQUIREMENTS .............................................................................. 7
3 PROBLEM STATEMENT AND DESIGN OBJECTIVES ..................................... 10
3.1
QUALITY FUNCTION DEPLOYMENT (QFD) ............................................ 10
3.2
PRODUCT DESIGN SPECIFICATION (PDS) ............................................... 11
4 PRELIMINARY DESIGNS ..................................................................................... 13
5 STATEMENT OF WORK AND DESIGN SCHEDULE ........................................ 18
6 REFERENCES ......................................................................................................... 25
APPENDIX I – EXISTING PATENTS ........................................................................... 26
Table of Figures
Figure 1 - Current United States Navy Cargo/Weapons Elevators [2] .................... 4
Figure 2 - Basic Design of Linear Induction Motor (LIM) [3]...................................... 5
Figure 3 - ENNA Linear-Motor-Driven Vertical Transportation System [7] ............. 7
Figure 4 - Land Based Engineering Sight Elevator System at Naval Surface ....... 8
Figure 5 - Quality Function Deployment Diagram (QFD) [1] ................................. 10
Figure 6 - Preliminary Design Concept #1 ................................................................. 13
Figure 7 - Preliminary Design Concept #2A .............................................................. 14
Figure 8 - Preliminary Design Concept #2B .............................................................. 15
Figure 9 - Preliminary Design Concept #3 ................................................................. 16
Figure 10 - Preliminary Design Concept #4 ............................................................... 17
Figure 11 – Gantt Chart ................................................................................................ 22
Figure 12 – PERT/CPM Chart...................................................................................... 23
Index of Tables
Table 1 – Decision Matrix ............................................................................................. 20
Table 2 – Total Manpower Estimate ........................................................................... 21
1
INTRODUCTION
The current system for conveying weapons and supplies aboard United
States naval vessels consists of a cable operated elevator configuration. The
U.S. Navy has taken the initial steps to radically redesign this system through the
use of linear induction motors thereby eliminating the need for cables. The
application of linear induction motors will theoretically allow the elevator to
operate on three axes rather than just one. This proposal will outline the efforts of
this design group to create a transition system that will transfer an elevator from
vertical to horizontal motion. The ability of a weapons and supply elevator to
move vertically and horizontally through the ship will dramatically improve the
capability of the ship to prepare for war as well as decrease the time needed to
replenish its supplies while at sea.[1]
The need for an elevator that operates in more than one axis has become
clearly apparent to those in charge of United States naval operations. Currently,
ships that must be replenished at sea require several days to process and stow
supplies (known as “strike down”) that have been dropped off by aircraft or
transferred via a pulley system. The primary reason for the sluggishness of this
process is the current elevator system. Supplies must be placed on the elevators,
taken to the appropriate deck, and then manually transported across the deck to
their proper stowage places. This process is not only slow, but also inefficient
and arduous for all involved.[1]
The design of a vertical to horizontal elevator transition system will greatly
improve the standard U.S. naval ordnance/cargo elevator. Preliminary design
concepts have been discussed among the four group members. A choice has
been made to go forth with a design effort to implement the most viable of the
preliminary design concepts. Later in this report the design requirements outlined
by the United States Navy, a Quality Function Deployment (QFD), and a Product
Design Specification (PDS) are included to further specify the aim of this design
effort. In addition, the needs and wants of the navy will be addressed. The design
group will show how these needs and wants are satisfied by the chosen design
concept.
Lastly, this proposal will set forth a list of tasks and objectives needed to
complete the design effort. This list is used to create an appropriate timeline to
finish each portion of the design effort. In addition, it is used to estimate the manhours needed to properly design, prototype and report this design effort.
Having now chosen a design and set forth a plan for making that design a
reality, the major tasks of designing and analyzing the system must be
undertaken. Barring unforeseen setbacks, it is the belief of the design group that
the project will be completed on time, and within budget.
2
BACKGROUND INFORMATION AND STATE-OF-THE-ART
2.1
BACKGROUND INFORMATION
In order to implement the type of elevator system the navy is requesting, the
team will require the use of a different type of propulsion system. Current supply
elevators aboard navy ships use a standard cable and wound drum
configuration.[2]
Figure 1 shows the cargo/weapons elevators that exist on current United
States Navy vessels. The elevator on the left of Figure 1 has a load capacity of
16,000 lbs, while the elevator on the right has a load capacity of 12,000 lbs.[2]
Figure 1 - Current United States Navy Cargo/Weapons Elevators [2]
The elevator cars ride on rails at each of the four corners, and are raised and
lowered from above by steel cables. This elevator design is unable to move in
more than one axis due to the hindrance of the cables. For this reason, the navy
is currently researching the use of linear induction motors (LIMs) for use with a
new elevator design.[1] The incorporation of LIMs would dramatically increase
the capabilities of elevators. Several cars could ride in the same elevator shafts,
and current height restrictions for cable driven elevators would be nullified.[3]
The basic linear induction motor design is shown in Figure 2. A LIM is a
rotary motor reconfigured by laying out its primary and secondary parts in a linear
fashion. Here, the secondary part is on the vehicle and the primary on the track.
The opposite configuration is also possible but unrealistic, as electricity would
have to be supplied to a moving car. [3]
Figure 2 - Basic Design of Linear Induction Motor (LIM) [3]
The linear induction motor has many modern applications. They are
implemented on roller coasters, monorails, and baggage carriers to name a few.
They are also capable of launching aircraft from naval carriers through the use of
a catapult system. A major manufacturer and distributor of LIMs is Force
Engineering. [4]
The basic operation of rotary induction motors (RIMs) is relatively simple.
An RIM has only 2 main parts, the rotor and the stator [5]. Around the stator are
wound two or three wires in a specific pattern – two or three wires depends on
whether the RIM is a two current or three current motor. As the appropriate
current is supplied to the windings, a rotating magnetic field is produced in the air
gap between the two main parts. This magnetic field induces currents within the
rotor which, at any instant, oppose the direction of the magnetic field. This
causes the rotor, as it spins, to be alternately attracted and repelled from the
stator. Thus, an induction motor is basically a constant speed motor. The speed
can be changed only by changing fixed parameters within the motor design.[6]
This system can be linearized by laying the rotor and stator flat against each
other. In this configuration, the rotor will move along a extended track of stators,
or vice versa. Therefore, in order to accelerate a roller coaster car, many motors
must be used along the track, each one inducting at a slightly higher speed. This
configuration creates a magnetic "wave" along the track, and the cars are pushed
ahead of the wave with permanent magnets affixed to the bottom of the cars.[5]
There are many advantages to linear induction motors over conventional
motors. LIM’s have no moving parts to get clogged or dirty, and therefore
maintenance is very minimal. On regular motors complications can be found in
gears, chains, and belts, while on LIM’s, these mechanisms are nonexistent. [4]
Induction motors can work at variable speeds and are able to accelerate and
decelerate rapidly despite the working conditions – underwater, hot or cold
surrounding temperatures, or even nuclear conditions.
Linear induction motors can serve in many ways, and Force Engineering
has distributed LIM’s for both means of transportation and pleasure. In 1991,
they sold 130 LIM’s to Euro Disney for use in the theme park rides, while in 1993,
500 LIM’s were purchased for use in the Senate People Mover in Washington,
DC. [4] The most significant success in the expanding use of the linear induction
motor was its first implementations into catapult systems in two roller coasters in
the United States. These catapults accelerate seven to nine ton cars to 70 miles
per hour in under four seconds. [4]
Beginning in 1989 and ending in 1995, the Underground Development
Utilization Research Center of the Engineering Advancement Association of
Japan (ENNA) began work on a linear-motor-driven vertical transportation
system. The test system was designed to run without the use of cables on a
vertical-to-horizontal curved or branched path. A schematic of the test system is
shown in Figure 3. [7]
Figure 3 - ENNA Linear-Motor-Driven Vertical Transportation System [7]
This test system was built to investigate and validate the use of LIMs in
elevator design. LIMs were used as the main propulsion while a cantilever beam
hung away from the track, connected to a carriage. The carriage was connected
to the cantilever in such a way that it rotated as the main cab rode along the track
and transitioned from vertical to horizontal travel. In this way, the designers of the
system were able to keep the carriage upright while it traveled the length of the
track. The design proved to be successful, but did not receive further funding for
implementation in mining as it was originally intended. [7]
A search was conducted on the United States Patent Office website
regarding elevators. The purpose of this research was to identify any existing
designs that would either aid or hinder this design effort. This search resulted in
the determination that there are no existing elevators which are capable of
performing the tasks required by this design effort. Patents which had some
correlation with this project were recorded and are provided in Appendix I along
with a short description.
2.2
DESIGN REQUIREMENTS
The Naval Surface Warfare Center (NSWC) has set forth some design
requirements that need to be incorporated into the finalized system. They have
also mentioned some features that they would like to see incorporated, but these
are not critical to the functioning of the system. Finally, some portions of the
project have remained undefined and have been left to the design group to
create. Figure 4 shows the current elevator system in operation at the Land
Based Engineering Sight at the Naval Surface Warfare Center in Philadelphia,
PA. This elevator will be the basis for future research and development. [2]
Figure 4 - Land Based Engineering Sight Elevator System at Naval Surface
Warfare Center (Philadelphia, PA) [2]
The vertical to horizontal transition system must have a vertical trunk that
has four T-rails as in the current elevator system. The four rail system needs to
be kept in place for several reasons. Since this is the existing system, the navy
has the resources for building and maintaining the current trunks, and it would be
economical in the long run to keep this structure. The four rails also provide
stability for the platform while at sea. In the case of a failure of up to three linear
induction motors, the brakes on the elevator platform will engage the four rails,
preventing the platform from free falling. The rail followers themselves must also
be in contact at all times. In the current aircraft carrier weapons elevators, rail
gaps are encountered because of explosion-proof hatches in the trunk that open
to let the platform travel through. The platform was designed with two sets of rail
followers, also called guide shoes, for each rail. When one is disengaged at the
gap, the second follower still remains in contact. The maximum rail gap distance
has been predefined to be 20 inches. The design parameters present in the
existing system may need to be altered due to the innovative nature of this
project. The new elevator will be rated at 24,000lbs and the platform itself will
weigh 10,000lbs. According to naval requirements, the dynamic load of the
elevator is considered to be 150% of the rated load to account for sea state
conditions. The combined stresses for each guide rail component shall not be
greater than 35 percent of the yield point of the material at any point. Another
criterion, while not finalized, requires that the reaction plates for the linear
induction drive be placed at the four corners of the long ends of the platform.
Most importantly, the entire rail switching process must be failsafe. If anything
were to stop working during the vertical/horizontal switch, the platform would not
freefall. [1]
According to Navy Elevator Mil Spec MIL-E-17807, the elevator system
must be designed to be failsafe in operation such that the ability to maintain the
safety of the weapons, cargo, equipment, and personnel at all times. Failure of
the power source or powered operated drive mechanism shall not result in
damage to the weapon, cargo or handling equipment, jeopardize the safety of
personnel, or result in uncontrolled movement of the equipment and load. In the
event of a power failure, the elevator shall be immobilized. [1]
The NSWC has also requested, but not required, that the switching
process be kept to a minimum amount of time and power. It was suggested that
the actuators used in the design be electrical rather than hydraulic or pneumatic,
since future naval vessels will be operated entirely on electrical power generated
at a central location. The design should also mimic the current elevator in terms
of general geometry, trunk orientation, control system, maintenance, and safety.
[1]
It has been left up to the design group to decide on the orientation of the
horizontal rails. Ideally, the navy would like a system that is able to switch an
elevator from the vertical direction to the fore and aft direction as well as the
cross ship direction, but for this design effort they only require that the elevator
move from vertical to horizontal and vice versa. The cross ship direction switch
can be done at a separate point in the trunk. The horizontal rail orientation
remains undefined; the constraints are stability in the pitch, roll and heave
environment found on ships.[1]
By using what is known about past elevator design and taking what is now
known about linear induction motors, it will be possible to blend the two
technologies together to create a radically new concept. The ultimate goal of this
design effort will be to successfully demonstrate a feasible transition system for a
LIM powered elevator. This system will allow the elevator to travel in three axes,
while fulfilling the design requirements set forth by the United States Navy.
3
3.1
PROBLEM STATEMENT AND DESIGN OBJECTIVES
QUALITY FUNCTION DEPLOYMENT (QFD)
1
3
9
9
3
1
9
3
3
9
9
3
3
1
3
9
Cargo Orientation
9
9
9
9
3
9
9
9
M
S
S
9
W
M
M
3
3
S
M
9
9
3
3
3
3
1
3
3
S
S
S
S
M
3
9
9
3
Lift capability
Fabrication Cost
Acutators
3
3
9
9
3
9
3
3
50
3
S
M
M
S
S
M
years
34,000
S W
lbs
9
S W M
50,000
S
$
9 9
W W M W M
15
3
sec.
Units
Transition Procedure
Time of transition
Reaction Plate Orientation
9
9
Customer Importance
3
3
9
9
3
1
Life Span of Apparatus
3
Guide Shoe Orientation
Factor of Safety
Rail Material
3
3
9
3
9
movments 5
Target Values
1
1.5
9 = Strong 3 = Moderate 1 = Weak
Functions
Vertical to horizontal transition
Constant contact
Stability
During power failure immobilize elevator
Dimensional similarity with current system
Strength
24,000lbs Rated load
150% of rated load
Total stress <35% of yield point
Ergonomics
Ease of use
Ease of maintanence
Ease of upgrade
Materials
Non-corrosive in seawater environment
Lightweight
Additional Features
Reaction plates at 4 corners
Minimize switching time
Minimize space used
Electric actuators
Cost
Technical Difficulty
Platform Material
Figure 5 shows the Quality Function Deployment Diagram (QFD). The
customer requirements are stated in the left column and are broken down into
categories of function, strength, ergonomics, materials and additional features.
All of the requirements are considered “needs” except for the additional features,
which are not critical to the design but still desirable. The engineering
characteristics are listed across the top, and the relationship matrix in the middle
shows the correspondence between the two groups. Customer importance is
ranked on the far right column according to the same scale as the relationship
matrix. Technical difficulty is along the bottom of the diagram; this row indicates
how complicated the design process for this particular characteristic will be. The
target values and units are based on preliminary design requirements and may
change as the design process progresses.
Figure 5 - Quality Function Deployment Diagram (QFD) [1]
3.2
PRODUCT DESIGN SPECIFICATION (PDS)
The PDS Statement was constructed using the information provided by
the Naval Surface Warfare Center in conjunction with research conducted by the
design group. This information was evaluated and simplified to form the PDS. [1]
Product Title
Vertical to Horizontal Transition System for U. S. Navy Ordnance/Cargo Elevator
Purpose
The purpose of this design effort is to design a system capable of allowing a
naval ordnance/cargo elevator to transition from vertical to horizontal motion.
New or Special Features
The cables used in typical elevator designs are eliminated.
The elevator car/platform is driven by linear induction motors.
The elevator car/platform will be able to move in more than one axis.
Competition
There are several contractors currently investigating this concept for the U.S.
Navy.
Intended Market
This design will be used primarily by naval warships, but can be extended to
civilian applications in the future.
Need for Product
The new capabilities of this design will greatly diminish the time necessary to
replenish the supplies of warships at sea.
It will become more convenient to transport ordnance and goods through naval
vessels.
Relationship to Existing Products Line
No products currently exist with the capabilities of the proposed design.
Market Demand
The primary customer would be the United States Navy, but the overall concept
could be marketed for hundreds of applications in the private sector.
Most common would be people movers within high-rise buildings.
Price
Price is not a main concern for the customer, as this is an experimental design.
Price considerations will be accounted for at a later date in the event the design
is mass- produced.
Functional Performance
The elevator must ride smoothly through transition in the railway system.
The elevator system must allow all possible ordnance and cargo configurations
to be carried without hindrance.
Physical Requirements
The new elevator system will be dimensionally equal to the current design to
facilitate ease of implementation and lessen the need for major redesign of naval
vessels.
The new design will need to meet the lifting capabilities of the current design.
The new design will be designed to withstand 150% of the expected operational
loads.
Service Environment
The elevator system will be implemented in future naval vessels.
The system will need to be able to function properly despite the normal wear
placed upon it by naval service.
The system must not be affected by the pitch and roll of the naval vessel.
Life-cycle Issues
Elevator must last the operational life of the vessel in which it is installed.
Normal repairs are expected, but should not affect the life of the elevator system.
Human Factors
Operation of the elevator system should be accomplished without the need for
special training by the operator.
Elevator system should transition from vertical to horizontal motion
autonomously.
Corporate Constraints
Elevator system must conform to Navy Elevator Mil Spec MIL-E-17807.
Legal Requirements
Elevator system must not impinge upon current elevator design patents.
4
PRELIMINARY DESIGNS
The major challenges of this design effort originate from the ultimate goal
of the project. The elevator must function while meeting all of the requirements
set forth by the US Navy. First, the cargo/ordnance elevator must remain in
contact with the four rails at all times. This makes transition from vertical to
horizontal motion difficult and unorthodox. Second, vertical rails must be
bypassed in order for the elevator to properly make the transition. Third,
accommodations must be made to keep the proper clearances between the
elevator and walls for the Linear Induction Motors. Fourth and most importantly,
the elevator must make the transition safely while bearing the large loads that will
be encountered through normal operation.
The preliminary design idea shown in Figure 6 shows an overall diagram
of the vertical to horizontal transition of the cargo/ordnance elevator. This design
contains two major features. First, two support rails move into place under the
elevator platform and engage the four corners of the platform. This action serves
a dual purpose. It acts to support the elevator from below and permits the
vertical rails at one end of the platform to disengage. This next major feature of
the design, the disengagement of the vertical rails, clears the horizontal path of
the cargo/ordnance elevator. The rails split in the middle and rotate ninety
degrees until they reengage with the horizontal rails. With the path clear and the
horizontal rails now fully engages, the elevator may pass from vertical to
horizontal motion along the four horizontal rails.
Figure 6 - Preliminary Design Concept #1
Figure 7 shows the basic layout of a stationary rail design. The stationary
sail design consists of a four rail system where the four rails are located at the
corners of the elevator platform. These rails are recessed into the surrounding
walls so that the platform moves with a specified clearance between the
platforms and the walls. Because of the spacing of the supporting rollers, the
rollers do not need to move when the platform needs to transition to horizontal
motion. At the rail intersections (Shown in Figure 8), the horizontal and vertical
rails meet at a perpendicular angle and the horizontal rails fit into a space in the
vertical rails as shown in the drawing. The elevator moves up or downwards until
the rollers are lined up with the horizontal rail sections and then the elevator can
simply move horizontally and the rollers will automatically engage the rails.
Because the rails are recessed into the surrounding walls, the rails will not
impede the elevator’s motion. If the elevator needs more stability while making
the transition, additional rollers can be designed to move from the elevator and
engage the horizontal rails.
Figure 7 - Preliminary Design Concept #2A
Figure 8 - Preliminary Design Concept #2B
This design involves rotating horizontal, C-shaped rails about an axis
between its to ends. The rails are also connected at its ends to a circular track
which allows them to rotate about the vertical axis and switch to either the fore/aft
or cross ship direction. This setup also uses the existing four T-rail (Parts D)
system common to the cargo elevators currently in use.
When the elevator platform approaches in the vertical direction the C-rails
(Parts A in Figure 9) are in their disengaged position. The elevator will continue
rising to a height marginally above the horizontal rails (Parts B). The C-rails will
then move to the “engaged” position by rotating about the horizontal axis. The
shape and size of the C-rails will allow them to move through a small gap in the
vertical rails. This gap will be smaller than the 20 inches proscribed by the navy.
When the C-rails are in the “engaged” position they will be in line with the
horizontal rails, some system that has yet to be determined will move the vertical
rails out of the way, and the car will lower onto the rails and be free to travel in
the horizontal direction. Another strength of this design is that when the elevator
platform is resting on the C-rails they will be able to rotate along the circular track
(Part C). This gives the elevator a third direction of motion, which will be greatly
advantageous when moving cargo through the ship.
Figure 9 - Preliminary Design Concept #3
Figure 10 shows the basic layout of preliminary design concept #4. In this
elevator design, there exist two systems of rails that the elevator platform will
travel along. The first rails are in the vertical direction, and will allow the elevator
to travel from level to level. In the drawing, the design is for the vertical rails to
ride through the short sides of the elevator platform. This does not necessarily
have to be the case. The rails can be located on the longer sides of the platform.
In both cases, the rails are “T” rails that will allow the linear induction motors to
travel along them. The second set of rails will be a horizontal pair, also “T” rails
for the same reason, but can be either “T” up or “T” down. The ideal situation
would be for the rails to be “T” down so as to reduce stress on the rails as the
platform travels across them. These rails will allow the platform to slide
horizontally through each individual deck. The engagement of the horizontal rails
will occur as follows. The platform will travel along the vertical rails to a distance
slightly above that of a given deck. The horizontal rails with then extend out
underneath the platform and engage with the linear induction motors under the
platform. After they engage, the vertical rails will then retract away from the
elevator platform in either a linear fashion or a circular manner, and the cart will
slide horizontally along the deck.
(Note: the vertical linear induction motors on the platform are not drawn, as well
as the followers on the vertical rails.)
Figure 10 - Preliminary Design Concept #4
5
STATEMENT OF WORK AND DESIGN SCHEDULE
The final design chosen from the preliminary designs set forth above is
Preliminary Design Concept #3 (Figure 9). The decision matrix shown in Table 1
provides a full breakdown of the factors leading to this choice. The strength of
this design lies in four main areas. First, the rotating rail feature allows for
contact between the guide rails and the guide shoes at all times. Other
preliminary designs either caused loss of contact between the rails and the rail
followers, or contained complex rail motion unsuitable for keeping the platform
stable. Secondly, the chosen design keeps the rails at the far corners of the long
end of the platform, similar to the current layout. This position allows for easy
loading and unloading of the elevator from any of its four sides, regardless of its
location in the ship’s hull. Moving the rails to the corners of the short sides would
obstruct the loading of the elevator at certain decks, and is therefore
unacceptable. The third characteristic that set the rotating rail design apart from
the others is its ability to rotate. This attribute will need simple, off-the-shelf
electric motors to actuate the major motion of the system. The other proposed
designs had rails moving in a telescoping or pivoting motions, requiring
expensive linear actuators. The rejected designs would also create cantilevered
rails to support the weight of the platform. These designs would have been
difficult to design to meet all of the necessary safety requirements. The C-shape
of the “flip-up” rails in the chosen design avoids high stress concentrations and
distributes the weight of the elevator car evenly. Finally, the rotating rail design
would allow for transition of the rail car in two horizontal directions, thus allowing
the car to move from bow to stern as well as port to starboard. These four design
attributes greatly distinguished the chosen design from the other preliminary
design.
The manpower estimate shown in Table 2 is based on predicted
completion times. The values displayed in this figure are liable to change during
the course of the project. In addition, team members are assigned to each of the
major design tasks.
The Gantt chart shown in Figure 11 was based on the manpower
estimates referenced above. In order to complete all of the tasks before the
deadline for this design effort, it is necessary to divide the work between the four
team members. During the course of the project, multiple design tasks will be
split up between the four group members. This allows the resources of the group
to be maximized and facilitates the timely completion of the project.
The Pert and CPM chart in Figure 12 reiterates the schedule laid out in the
Gantt chart. It also displays the critical path of the project, which dictates the
limiting tasks hindering the progression of the design effort.
The cost estimate analysis is being developed in conjunction with the navy
and fabricators. A detailed figure was requested by the navy so the proper
amount of money may be allotted to this design effort before the end of the
calendar year. Talks are currently continuing between the design group, the U.S.
Navy, and possible prototype fabricators. It is the understanding of the design
group at this time that the navy has sufficient funds to allocate to this project.
Table 1 – Decision Matrix
Criteria
Vertical to horizontal transition
Constant Contact
Stability
During Power Failure immobilize elevator
Dimensional Similarity with Current system
Switch to cross-ship direction
Rail Gap < 20"
24,000 lbs rated load
150% strength of rated load
Total stress at any point <35% of yield point
Ease of use
Ease of maintenance
Ease of upgrade
Non-corrosive material in seawater environment
Lightweight
Linear induction motor does not obstruct load/unload
Rail orientation does not obstruct load/unload
Minimize switching time
Minimize space used
Electric actuators
Cost
Overall Rating
Weight
10
10
7
9
6
2
8
6
9
9
4
4
5
7
7
6
6
3
5
2
4
129
Weight Fraction
0.08
0.08
0.05
0.07
0.05
0.02
0.06
0.05
0.07
0.07
0.03
0.03
0.04
0.05
0.05
0.05
0.05
0.02
0.04
0.02
0.03
I - Folding Rails
90
6.98
10
0.78
30
1.63
60
4.19
40
1.86
0
0.00
100
6.20
100
4.65
100
6.98
90
6.28
90
2.79
70
2.17
50
1.94
60
3.26
90
4.88
90
4.19
10
0.47
70
1.63
90
3.49
80
1.24
80
2.48
68.06
II - Stationary Rails
80
6.20
10
0.78
30
1.63
60
4.19
10
0.47
0
0.00
100
6.20
100
4.65
100
6.98
80
5.58
80
2.48
80
2.48
50
1.94
60
3.26
100
5.43
90
4.19
10
0.47
80
1.86
90
3.49
100
1.55
70
2.17
65.97
Concepts
III - Rotating Rails IV - Retracting Rails V - Two Part Elevator
90
6.98
80
6.20
100
7.75
100
7.75
70
5.43
100
7.75
50
2.71
30
1.63
100
5.43
70
4.88
70
4.88
30
2.09
90
4.19
90
4.19
40
1.86
100
1.55
0
0.00
0
0.00
100
6.20
100
6.20
100
6.20
100
4.65
100
4.65
100
4.65
100
6.98
100
6.98
100
6.98
60
4.19
60
4.19
60
4.19
40
1.24
30
0.93
10
0.31
40
1.24
30
0.93
40
1.24
60
2.33
50
1.94
40
1.55
60
3.26
60
3.26
60
3.26
60
3.26
70
3.80
30
1.63
100
4.65
90
4.19
10
0.47
100
4.65
90
4.19
10
0.47
60
1.40
60
1.40
50
1.16
60
2.33
60
2.33
90
3.49
100
1.55
70
1.09
100
1.55
40
1.24
40
1.24
60
1.86
77.21
69.61
63.88
Table 2 – Total Manpower Estimate
Task Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Project Tasks
Design Elevator Chassis/Car
Design Vertical Rail Reposistioners
Design Flip-up Rails and Rail Mounts
Design New Horizontal Rails
Design Horizontal Rail Followers
Analyze Stresses on Chassis/Car
Analyze Stresses on Vertical Rails Repositioners
Analyze Integrity of existing Vertical Rail Followers
Analyze Stresses on Flip-Up Rails and Mounts
Analyze Stresses on New Horizontal Rails
Analyze Stresses and Integrity on New Followers and follower positions
Analyze Stresses on actuators/motors
Prepare for Mid-Semester report
Choose appropriate actuators/motors
Create Final Design drawings and specifications
Choose Contractor to manufacture prototype
Build working prototype
Test working prototype
Make design corrections based on prototype testing
Update design drawings to include design corrections
Prepare for oral presentation
Write final design report for customer
Number of Days
to Complete
14
21
17
10
8
11
14
6
7
7
7
10
3
7
40
7
40
7
7
7
7
36
Team Member(s)
Hours Per Day Per
Man-hours
Assigned
Person
Ben, Brian
2
56
Dan, Tim
2
84
Dan, Tim
1
34
Ben, Brian
0.5
10
Ben, Brian
0.25
4
Ben, Brian
2
44
Dan, Tim
2
56
Dan, Tim
1
12
Dan, Tim
2
28
Ben, Brian
1
14
Dan, Tim
2
28
Ben, Brian
1
20
Group Effort
2
24
Ben, Brian
0.25
3.5
Group Effort
1
40
Group Effort
0.25
1.75
Contractor and Group
2
80
Group Effort
1
7
Group Effort
1
7
Group Effort
0.5
3.5
Group Effort
1
28
Group Effort
1
36
Total Man-Hours
620.75
hours
Figure 11 – Gantt Chart
Analyze
Stresses on
Chassis/Car
ET
LT
8 days
14 days
Design Elevator
Chassis/ Car
ET
Analyze Stresses
on
Actuators/Motors
LT
10 days 20 days
Design Flip-up
Rails and Rail
Mounts
ET
14 days 21 days
Choose
Contractor to
Manufacture
Prototype
ET
LT
4 days
10 days
ET
LT
5 days 10 days
Update Design
Draw ings
ET
LT
5 days
10 days
ET
ET
Prepare
Mid-Sem ester
Report
ET
LT
1 days
5 days
Build Working
Prototype
ET
LT
35 days 45 days
Create Design
Drawings and
Design
Specifications
LT
4 days 8 days
LT
17 days 27 days
ET
LT
35 days
45 days
Test Working
Prototype
ET
LT
5 days
10 days
Make Design
Corrections
ET
Write Final
Design Report
LT
ET
5 days 10 days
Prepare Oral
Presentation
ET
ET
ET
LT
7 days 14 days
LT
12 days 21 days
Design
Horizontal Rail
Follow ers
ET
LT
6 days 10 days
Analyze Stresses
and Integrity on
New Horizontal
Follow ers and
Follow er Positions
ET
LT
5 days 10 days
Analyze
Stresses on
New
Horizontal
Rails
ET
LT
5 days
10 days
LT
5 days 10 days
Analyze
Stresses on
Vertical Rail
Repositioners
Design New
Horizontal
Rails
LT
5 days 10 days
Analyze
Integrity of
Existing
Vertical Rail
Follow ers
Design Vertical
Rail
Repositioners
ET
LT
12 days
Analyze
Stresses on
Flip-up Rails
and Mounts
LT
Begin
Design
Effort
ET
7 days
Choose
Appropriate
Actuators/Motors
Figure 12 – PERT/CPM Chart
(Note: PERT/CPM chart constructed using trial version of SmartDraw Software)
LT
20 days 30 days
End of
Design
Effort
CONCLUSION
As previously stated, there are many challenges facing the design of this
multidirectional elevator. The design must comply with all load requirements set
forth by the navy and it must safely transition from vertical to horizontal motion.
The four designs set forth try to incorporate all of the requirements of the elevator
while using very different ideas of how the elevator will operate. They consist of
both stationary and movable rails, and many different support and roller
configurations. These designs will be critiqued and analyzed to determine which
design will be pursued as the final design proposal.
CONCLUSION
This design effort will become successful by using what is known about past
elevator design and taking what is now known about linear induction motors
(LIMs). The two technologies will be blended together to create a radically new
concept. The major requirement of this design effort will be to successfully
demonstrate a feasible transition system for an ordnance/cargo elevator powered
by LIMs. This system will allow the elevator to travel in three axes, while fulfilling
the design and safety requirements set forth by the United States Navy.
6
REFERENCES
1. Poole, Kenneth J., Naval Surface Warfare Center - Carderock; Personal
Conversation, 12 Sept 2003..
2. McCammon, Thomas, 1997. U.S. Navy Shipboard Elevator. Elevator World
Magazine; September 1997 Issue. Pp. 64-67.
3. Fabian, Lawrence, 2000. Going out on a L.I.M: Linear Induction Motors for
Horizontal and Vertical Transport. Elevator World Magazine; March 2000
Issue. Pp. 63-67.
4. http://www.force.co.uk/, 29 September 2003. (No Authors Given)
5. http://www.me.utexas.edu/~uer/roller/tech.html, 29 September 2003.
(No Authors Given)
6. Avallone and Baumeister, Ed., Marks' Standard Handbook for Mechanical
Engineers, Tenth Edition, McGraw-Hill, 1996
7. Editorial. Linear-Motor-Driven Vertical Transportation System. Elevator World
Magazine; September 1996 Issue. Pp. 66-73.
8. http://www.uspto.gov/, 28 September 2003. (No Authors Given)
APPENDIX I – EXISTING PATENTS
Note: All patent searches carried out on the United States Patent Office
Website.[8]
Patent Search for Elevators driven by Linear Induction Motors
No Hits for “multi-directional elevators” or any variation. Multiple hits for
elevators driven by linear induction motors. Search Criteria: “Linear
Elevator”.
Patent # 6,305,501
Elevator reluctance linear motor drive system
Abstract
A drive system for an elevator includes a drive machine by means of which the
for moving and supporting an elevator car. The primary circuit of a linear motor is
permanently fitted to a wall of a building while its secondary circuit is fitted in
conjunction with the elevator car and moves with the elevator car. Pressurized air
is supplied between the primary and secondary circuits of the reluctance-type
linear motor to maintain an air gap between them.
Inventors:
Kahkipuro; Matti (Hyvinkaa, FI); Pelto-Huikko; Raimo
(Vantaa, FI); Kallioniemi; Antti (Helsinki, FI)
Assignee:
Kone Corporation (Helsinki, FI)
Appl. No.:
446063
Filed:
March 14, 2000
PCT Filed:
June 18, 1998
PCT NO:
PCT/FI98/00531
371 Date:
March 14, 2000
102(e) Date:
March 14, 2000
PCT PUB.NO.: WO98/58866
PCT PUB. Date: December 30, 1998
The present invention relates to an elevator and in particular, to a drive system
for an elevator.
DESCRIPTION OF THE BACKGROUND ART
In elevator technology, several methods are used to produce the motive power
for elevators. A common method is to use a traction sheave connected to a
rotating motor hoisting the elevator car by means of ropes, with a counterweight
placed on the opposite side of the traction sheave to balance the load. Another
established solution is found in hydraulic elevators, in which the hoisting power to
move the car is obtained from hydraulic cylinders either directly or via ropes.
Most modern elevators are based on these solutions, of which many variations
have been developed.
Although the above-mentioned elevator types have become established and are
safe and reliable in operation, the solutions used in them comprise several
factors that are objections of improvement and product development. For
example, investigations are continuously being made to find ways of more
effective utilisation of building space and reduction of energy consumption. For
hydraulic elevators, the hoisting height is in practice limited to a few floors. By
contrast, elevators with rope suspension have been installed in buildings as high
as several hundred meters, in which case rope elongation and oscillation cause
problems. Because of the rope suspension arrangements, the number of
elevators in a shaft is practically limited to one.
In addition to rope-suspended and hydraulic elevators, several solutions for the
use of a linear motor in an elevator have been proposed. In this case the
induction motor is completely located in the shaft space. Most linear elevator
motors have been based on the induction motor principle, although other motor
types, such as a linear motor based on permanent magnets have also been
presented. Several different solutions have been proposed, but as yet it has not
been possible to produce a competitive elevator.
SUMMARY OF THE INVENTION
The object of the present invention is to achieve a new elevator in which several
drawbacks encountered in prior art solutions are avoided.
The invention is based on a so-called switched reluctance linear motor or a
variant developed from it, which makes use of the so-called microflux technique.
In the switched reluctance motor, the windings of the linear motor are optionally
placed either in a fixed primary circuit or in a movable secondary circuit. The
motor is used to both move the car and support it by generating a force
component in the direction of motion and a force component perpendicular to the
direction of motion. The placement of the winding on the primary or secondary
side can be selected separately for each application.
According to a preferred embodiment of the invention it is utilised the combined
effect of a linear motor and pneumatic air gap regulation. The linear motor is
used to both move the car and support it by generating a force component in the
direction of motion and a force component perpendicular to the direction of
motion. The air gap between the primary and secondary circuits of the linear
motor is maintained by means of the perpendicular component and pressurised
air.
According to a preferred embodiment of the invention, in a motor based on the
microflux technique, called microflux motor, the windings are placed on both the
primary and secondary sides, thus reducing the proportion of leakage flux and
improving the power-to-weight ratio of the motor. The supply of current to the
windings is so controlled that the magnetic flux will only pass through a minimal
distance in the yoke part of the motor and that the flux loop will be completed in
the first place via adjacent teeth.
According to a preferred embodiment, the power is supplied to the windings
using control equipment disposed along the entire length of the track of the
elevator and each winding is controlled separately. Alternatively, several
windings can be combined to form a group with common control.
According to another alternative implementation of the invention, the pneumatic
equipment comprises a source of pressurised air and a pipe system with nozzles,
fitted substantially in the air gap between the primary and secondary circuits of
the linear motor. The pressurised air keeps the air gap clean and generates a
smooth air flow from the center of the air gap towards its edges.
The alternatives regarding the structural solutions of the invention are to dispose
the linear motor and pneumatic equipment on one side of the elevator car or to
dispose the linear motor and pneumatic equipment on two or more sides of the
elevator car. The former solution provides more freedom regarding the
placement of the elevator in the building and an independence of a traditional
elevator shaft. The latter solution allows more freedom of variation of the physical
dimensions of the elevator-specific motor.
In an embodiment of the invention relating especially to the structure of the linear
motor, the tooth pitch of the primary and secondary circuits is effected by
applying the vernier principle. The motor power can thus be uniformly distributed
over the entire length of the active part of the motor, i.e. the movable secondary
side.
According to a further embodiment, the primary circuit and/or secondary circuit is
coated with a plastic film on the surface facing the air gap. The effective air gap
of the linear motor can thus be adjusted without increasing the pneumatically
regulated air gap at the same time.
The new type of motor solution of the invention provides several advantages in
elevator technology. As the motor applies a lifting force directly to the elevator
car, it eliminates the need for hoisting ropes, which are an object of regular
maintenance and renewal. Readjustments due to rope elongation naturally
become unnecessary. Correspondingly, no traction sheave and no diverting
pulleys need to be installed. The counterweight and associated shaft equipment,
such as counterweight guide rails, become superfluous. No separate machine
room is needed, but the control and operating equipment can be placed in the
elevator or in conjunction with the equipment at the landings. The travel of the
elevator car in the elevator shaft is controlled by a pneumatic bearing system, so
there are no conventional car guides and guide rails installed for them. Safety
gears as used in current technology are also left out. The overall degree of
utilisation of the elevator shaft is higher because the only equipment that needs
to be installed in the elevator shaft in addition to the elevator car is the very flat
magnetic circuits of the motor. The lifting height is unlimited without any special
additional equipment or rigging necessitated by height.
The elevator can be implemented as a external installation in which the elevator
climbs along the external wall of the building, thus allowing a further space
saving inside the building. In the elevator solution of the invention it is further
possible to use a light car construction because the magnitude of the friction
does not limit the minimum car weight as in the case of traction sheave elevators.
Based on the degrees of freedom of the elevator of the invention and the
limitations of conventional elevators, this new solution provides advantages
especially in the case of very high and very short elevator shafts. Furthermore,
the elevator solution of the present invention makes it possible to develop
multiple-car elevator shafts and also transport systems combining vertical and
horizontal movement.
The switched reluctance motor has a considerably higher power-to-weight ratio
than conventional motor solutions. In the microflux motor, the power-to-weight
ratio can be further improved as compared even with the reluctance motor.
Further scope of the applicability of the present invention will become apparent
from the detailed description given hereinafter. However, it should be understood
that the detailed description and specific examples, while indicating preferred
embodiments of the invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the invention will
become apparent to those skilled in the art from this detailed description.
Patent # 5,203,432
United States Patent
Grinaski
5,203,432
April 20, 1993
Flat linear motor driven elevator
Abstract
A flat, single-sided linear motor driven elevator minimizes a moment on a primary
element assembly towards a secondary element by aligning and balancing a
center of gravity of the primary element assembly along the plane of an air gap
between the primary and secondary elements of the linear motor. Ropes
supporting the primary element assembly are attached thereto, and weights are
positioned on a side of the plane, other than the side of the plane on which the
primary element is disposed, to balance the centers of gravity and thrust of the
primary assembly along the plane.
Inventors: Grinaski; Timothy J. (East Hartford, CT)
Assignee: Otis Elevator Company (Farmington, CT)
Appl. No.: 793056
Filed:
November 15, 1991
Current U.S. Class:
Intern'l Class:
Field of Search:
187/251; 187/404; 310/12
B66B 017/12
187/18,17,94,112 310/12,13,14
TECHNICAL FIELD
This invention relates to an elevator, and more particularly to an elevator driven
by a flat linear motor.
BACKGROUND OF THE INVENTION
Usually, an elevator's drive sheave and motor are arranged above the elevator
car in a machine room. In buildings, where space is at a premium, machine
rooms are not desirable. Some elevators are powered by linear motors, which
provide motive force for the elevator within a hoistway, and do not require a
machine room.
Some linear motor driven elevators have a tubular primary element disposed
around a tubular secondary element. The tubular secondary element is hung
from the top of the hoistway. At present, it is impractical to hang a secondary
element over an extended rise.
UK Patent Application 2,237,555 A to Toshiba shows another type of linear motor
driven elevator which has a flat secondary and a flat primary element. The
secondary element is affixed to the hoistway thereby avoiding the problem of
hanging the secondary element from the top of the hoistway. The primary
assembly of Toshiba is guided by the secondary thereby avoiding the necessity
of mounting additional guide rails for the primary assembly.
Flat linear elevator motors balance the relatively large normal forces (as
compared to thrust forces) between the primary and secondary elements to
maintain an air gap therebetween. If the air gap is too great the motor is
inefficient. If the air gap is too small, the motor may short itself out.
DISCLOSURE OF THE INVENTION
It is an object of the invention to provide an elevator linear motor which minimizes
the effect of forces between the primary element and secondary element of the
linear motor.
It is a further object of the invention to minimize the forces upon guides disposed
between the primary and secondary elements of the linear motor.
It is a further object of the invention to provide a linear motor which has an air
gap that can be more readily controlled.
According to the invention, a flat, single-sided linear motor driven elevator
minimizes a moment of a primary element assembly towards the secondary
element by aligning and balancing the coincident centers of gravity and thrust of
the primary element assembly along a plane of an air gap between the primary
and secondary elements of the linear motor. Ropes supporting the primary
element assembly are attached thereto, and weights are positioned on a side of
the plane, other than the side of the plane on which the primary element is
disposed, to balance the center of gravity of the primary assembly along the
plane.
By aligning the primary element assembly along the plane, guides disposed
between the primary and secondary elements are protected against excessive
wear because the forces of any moment due to misalignment with the plane are
minimized. Also, the air gap may be more closely controlled because the effect of
moments on the primary assembly are minimized.
These and other objects, features, and advantages of the present invention will
become more apparent in light of the following detailed description of a best
mode embodiment thereof, as illustrated in the accompanying drawing.
Patent # 5,141,082
United States Patent
Ishii , et al.
5,141,082
August 25, 1992
Linear motor elevator system
Abstract
A linear motor elevation system comprising an elongated magnetic induction
member (21) mounted along the hoistway. The induction member (21) has a
plurality of magnetic poles (21a) disposed at equal intervals along the hoistway
so that they face toward the armature (27). An elevator car (4) or a counter
weight has attached thereto a field magnet (26) disposed in a facing relationship
with respect to the magnetic induction member (21) for generating magnetic
poles in the induction member (21). The field magnet (26) comprises an iron core
(23) having a U-shaped cross section including a central web portion on which a
field winding 24 is wound and parallel flange portions extending from the web
portion toward the magnetic induction member (21). An armature (27) comprising
armature windings (25) wound on teeth formed in the magnetic induction
member (21) is also disposed on the car (4) in a facing relationship with resepct
to the magnetic induction member (21) for generating a progressive magnetic
field acting on the magnetic induction member (21) to generate an
electromagnetic drive force for moving the car (4) along the hoistway. The
magnetic induction element (31) may have a guide surface which is in guiding
engagement with guide rollers (41) mounted on the car (4) for guiding it along the
hoistway.
Inventors: Ishii; Toshiaki (all c/o Mitsubishi Denki Kabushiki Kaisha Inazawa
Seisakusho 1, Hishimachi, Inazawa-shi, Aichi-ken, JP); Ikejima;
Hiroyuki (all c/o Mitsubishi Denki Kabushiki Kaisha Inazawa
Seisakusho 1, Hishimachi, Inazawa-shi, Aichi-ken, JP); Yosikawa;
Hirosi (all c/o Mitsubishi Denki Kabushiki Kaisha Inazawa Seisakusho
1, Hishimachi, Inazawa-shi, Aichi-ken, JP); Sugita; Kazuhiko (all c/o
Mitsubishi Denki Kabushiki Kaisha Inazawa Seisakusho 1, Hishimachi,
Inazawa-shi, Aichi-ken, JP); Sakabe; Shigekazu (both c/o Mitsubishi
Denki Kabushiki Kaisha Sangyo System Kenkyusho, 1-1,, Amagasakishi, Hyogo-ken, JP); Sugimoto; Hidehiko (both c/o Mitsubishi Denki
Kabushiki Kaisha Sangyo System Kenkyusho, 1-1,, Amagasaki-shi,
Hyogo-ken, JP); Maehara; Toshiaki (both c/o Mitsubishi Denki
Kabushiki Kaisha Nagoya Seisakusho, 1-14,, Nagoya-shi, Aichi-ken,
JP); Kisimoto; Takesi (both c/o Mitsubishi Denki Kabushiki Kaisha
Nagoya Seisakusho, 1-14,, Nagoya-shi, Aichi-ken, JP)
Appl. No.: 712102
Filed:
June 7, 1991
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a linear motor
elevator system free from the above discussed problems of the conventional
linear motor elevator system.
Another object of the present invention is to provide a linear motor elevator
system simple in structure.
Another object of the present invention is to provide a linear motor elevator
system easily manufactured and installed.
A further object of the present invention is to provide a linear motor elevator
system which is inexpensive.
A still further object of the present invention is to provide a linear motor elevator
system improved in the power factor of the linear motor.
Another object of the present invention is to provide a linear motor elevator
system improved in the linear motor structure.
With the above objects in view, the linear motor elevator system comprises a
movable body such as an elevator car or a counter weight disposed within a
hoistway and an elongated magnetic induction member installed within the
hoistway and extending along the hoistway. The elevator system also comprises
a field magnet disposed on the movable body in a facing relationship with respect
to the magnetic induction member for generating magnetic poles in the magnetic
induction member. An armature is disposed on the movable body in a facing
relationship with respect to the magnetic induction member so that a progressive
magnetic field acting on the magnetic induction member is generated to generate
a drive force for moving the movable member along the hoistway.
The magnetic induction member may comprise an elongated magnetic plate
extending along the hoistway and a plurality of magnetic poles disposed on the
elongated plate at a substantially equal intervals along the hoistway, the
magnetic poles facing toward the armature on the movable body.
The field magnet may comprise an iron core having a substantially U-shaped
cross section including a central web portion and parallel flange portions
extending from the web portion, the flange portions extending toward the
magnetic induction member, and a field winding disposed on the web portion of
of the iron core. The armature may comprise a magnetic iron core having a
plurality of teeth arranged along the magnetic induction member and a plurality of
armature windings wound on the teeth.
Alternatively, the linear motor elevator system of the present invention may
comprises an elongated, rigid magnetic induction member extending along the
hoistway and defining a guide surface for guiding the movable body therealong.
A pair of field magnets are disposed on the movable body in a spaced, opposing
relationship to each other for receiving the magnetic induction member
therebetween, for generating magnetic poles in the magnetic induction member.
Armatures are disposed on the field magnets in a facing relationship with respect
to the magnetic induction member and generating progressive magnetic fields
acting on the magnetic induction member to generate an electromagnetic drive
force for moving the movable member along the hoistway. The movable body
has mounted thereon a guide unit including a guide rollers which is in guided
engagement with the guide surface on the magnetic induction element for
guiding the movable body along the hoistway.