GB2383473A

GB2383473A - Dual linear induction motor propulsion arrangement

Info

Publication number: GB2383473A
Application number: GB0130887A
Authority: GB
Inventors: Robert Charles Knowlton
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-12-22
Filing date: 2001-12-22
Publication date: 2003-06-25
Also published as: GB0130887D0

Abstract

An object (eg lift or train) 2 comprises two parallel linear induction motor assemblies each comprising a primary member 28,29 and a secondary member 30,31. Independently varying the current flow in secondary windings 56,58 allows the object to be laterally displaced so as to allow direction changes at junctions formed by the rails 18,20 Auxiliary windings provide emergency lift and traction, ie windings 57,59 in planar sheets 36,38, windings 51,53 disposed relative to the slot 22 and winding 55 disposed relative to the rails 18,20, distance sensors 72-76 being provided. Winding 55 also centralise the object between primary members. The apparatus further comprises a power supply for the linear induction motor assemblies, and associated power control means for traction, steering, levitation, braking, and emergency movement.

Description

A METHOD AND APPARATUS FOR PROPELLING AN OBJECT USING ELECTROMOTIVE FORCE The present invention relates to a method and apparatus for propelling an object using an electromotive force and a method and apparatus for changing the direction of an object using electromotive force and is concerned particularly, although not exclusively, with a method and apparatus for propelling a vehicle using linear motor assemblies and a method and apparatus for changing the direction of a vehicle using linear motor assemblies.

Generally, when referring to linear induction motors (LIM) instead of the terms stator and rotor, which are used for rotary induction motor, the respective terms primary member and secondary member are used.

Applications of LIM include transportation, materials handling, slidingdoor closer and curtain pullers. Usually, in a transportation application, such as a train vehicle, the LIM assembly comprises a moveable primary member attached to the vehicle and a fixed secondary member on the track.

According to a first aspect of the present invention there is provided an apparatus for propelling an object, the apparatus comprising two linear induction motor assemblies each comprising a primary member and a secondary member the longitudinal axis of one linear induction motor being substantially parallel to the longitudinal axis of the other linear induction motor and one member of each linear induction motor assembly being attached to the object, a power supply for the linear induction motor assemblies, and control means for controlling the power.

Preferably, the two linear induction motor assemblies are tubular linear induction motor assemblies.

Preferably, each linear induction motor assembly comprises a substantially C-shaped secondary member.

Each tubular linear induction motor assembly preferably comprises a moveable secondary member and a fixed primary member.

Each moveable secondary member is preferably attached to the object.

The fixed primary members preferably comprise semi-circular laminated cores with three phase windings wound thereon.

The secondary members preferably form a substantially H-shaped laminated core comprising two windings, the arrangement being such that the two windings are positioned between the primary members.

The H-shaped laminated core preferably forms auxiliary secondary member means the arrangement being such that in use the auxiliary secondary member means provides additional directional force and lift.

The apparatus for propelling an object preferably comprises means for guiding the object.

The means for guiding the object preferably comprises a track.

In an embodiment of the present invention the means for guiding the object comprises a network of tracks.

Preferably the arrangement of the apparatus for propelling an object is such that in use the control means can independently vary the current flow in each of the secondary members in order to produce a movement of the object in a direction that is substantially perpendicular to the longitudinal axis of the secondary members.

The movement of the object in a direction that is substantially perpendicular to the longitudinal axis of the secondary members is preferably used for guiding the object from a first section of track to a second section of track.

The control means preferably comprises sensors for measuring the movement of the object in a direction that is substantially perpendicular to the longitudinal axis of the secondary members.

According to a second aspect of the present invention there is provided a method for changing the direction of an object, said method using apparatus according to the first aspect of the present invention, the method comprising independently varying the current flow in a pair of secondary members of a linear induction motor assembly in order to produce a movement of the object in a direction that is substantially perpendicular to the longitudinal axis of the secondary members.

The present invention may be carried into practice in various ways and two embodiments will now be described, by way of example only, with reference to the accompanying drawing in which: Figure 1 is a plan view of a section through apparatus for propelling a lift car; Figure 2 is a plan view of a section through apparatus for propelling a lift, the apparatus comprising auxiliary secondary windings ; Figure 3 is a schematic diagram of the elements of the apparatus shown in Figure 2;

Figure 4 is a view of a section through apparatus for propelling a train carriage; Figure 5 is a schematic diagram of the elements of the apparatus shown in Figure 4; Figure 6 is a plan view of the guide tracks of the apparatus shown in Figure 4; Figure 7 is an isometric view of a primary member of the apparatus shown in Figures 1, 2 and 4 and shows one winding on the laminated core; Figure 8 is an isometric view of the primary member shown in Figures 7 and shows multiple windings on the laminated core; and Figure 9 is a plan view of the primary members and secondary members of the apparatus shown in Figures 1,2 and 4 and excluding respectively the lift car and the train carriage.

With reference to Figure 1 there is shown apparatus 1 for propelling a lift car 2. The apparatus comprises a vertical tubular support frame 4.

The tubular support frame 4 has a substantially rectangular cross-section formed from two side walls 6,8 a base wall 10 and a top wall 12.

Extending perpendicularly inward from each side wall is a longitudinal support rail 14,16. Each support rail 14,16 extends along the longitudinal length of the respective side walls 6,8. The base wall 10 is formed with two sets of parallel guide rails 18,20 extending inwardly therefrom. The top wall 12 is formed with a longitudinal slot 22 extending along the longitudinal length of the top wall 12.

Disposed within the tubular support frame 4 there are two linear induction motor assemblies 24,26. Each linear induction motor assembly 24,26 comprises a fixed primary member 28,29, which extends along the longitudinal length of the tubular support frame 4 and a moveable secondary member 30,31. The longitudinal axis of the first linear induction motor 28 is substantially parallel to the longitudinal axis of the second linear induction motor 30.

The primary member 28 is attached to one of the longitudinal support rails 14. The primary member 29 is attached to the other longitudinal support rail 16. The primary member 28 and the secondary member 30 form a tubular linear induction motor arrangement. The primary member 29 and the secondary member 31 also form a second tubular linear induction motor arrangement.

Each secondary member 30, 31 is a substantially C-shaped channel within which respective primary members 28,29 extend there through. There is an air gap 32 between the primary member 28 and the secondary member 30 and there is an air gap 34 between the primary member 29 and the secondary member 31.

An upper planar sheet 36 extends between a side of each of the secondary members 30,31 and a lower planar sheet 38 extends between the other side of each of the secondary members 30, 31. The lift car 2 is attached to the upper planar sheet by a roller bearing assembly 37 that extends through the slot 22.

Extending from the lower planar sheet 38 there are two inverted crossshaped guide members 40,42. Each distal end of the cross-shaped guide members 40,42 is received within the one of the sets of parallel guide rails 18,20.

With reference to Figures 7 and 8 the primary member 29 comprises a central core 50 that is formed with a series of laminations forming an array of semi-circular slots 52. A three-phase winding 54 (only one winding shown in Figure 7) is wound onto the core 50 and the winding 54 is received within the semi-circular slots 52. The windings 54 are such that in use they are in phase in time and space. The primary member 28 comprises substantially the same elements as the primary member 29.

The two secondary members 30, 31; the upper planar sheet 36 and the lower planar sheet 38 form an H-shaped laminated core. The laminated core is positioned between the two primary members 28,29.

In use the apparatus 1 will provide a lifting force and a propelling force in the direction of the longitudinal axis of the primary members 28,29. The current flow in the secondary windings can be varied independently of each other using control means.

With reference to Figure 2 the two secondary members 30,31 comprises a set of respective windings 56,58 and the upper planar sheet 36 comprises windings 57 and the lower planar sheet 38 comprises windings 59. The apparatus 1 comprises a pair of upper secondary windings 51, 53 attached to the inner surface of the top wall 12. The upper primary auxiliary windings 51,53 are disposed either side of the slot 22. Disposed on the inner surface of the bottom wall 10 there is a lower primary auxiliary winding 55.

The control means 60 (shown in Figure 3) comprises means 62 for controlling the electrical power supply 64 to the secondary windings 54. The means 62 is in communication with a main controller 66 and with controllers 68 further along the apparatus 1. The control means 60 also

comprises means 70 for controlling the slip, speed, steering and level of the H-shaped laminated core and hence the lift car 2. The control means 70 is in communication with five distance sensors 72,73, 74, 75, 76.

The distance sensor 72 detects the separation between the primary member 29 and the secondary member 31. The distance sensor 73 detects the separation between the upper primary auxiliary windings 51 and the windings 57 of the upper planar sheet 36. The distance sensor 74 detects the separation between the primary member 28 and the secondary member 30. The distance sensor 75 detects the separation between the upper primary auxiliary windings 53 and the windings 57 of the upper planar sheet 36. The distance sensor 76 detects the separation between the lower primary auxiliary windings 55 and the windings 59 of the lower planar sheet 38. The apparatus 1 may also comprises an auxiliary power supply 61.

A variable frequency three-phase supply 64 is connected to each of the windings 54 of the primary members 28,29. When power is supplied to the primary members 28,29 this will produce an equal and opposite force in the secondary members 30,31 that will propel the lift car 2 along the length of the tubular support frame 6. By varying the current flow in the secondary members 30, 31 equally, the secondary members 30,31 will tend to slip and slow down. Changing the current flow in the secondary members 30, 31 independently will pull the H-shaped laminated core and so the lift car 2 towards one of the primary members 28,29 and so giving sideways movement. The use of this sideways movement towards one of the primary members 28,29 may be used to change direction of the lift car 2. The air gap between the primary members 28,29 and the respective secondary members 30,31 will be sufficient that the respective members will never touch.

With reference to Figures 4,5 and 6, a train car 80 is attached to the Hshaped laminated core of apparatus 1. In this embodiment of the present invention the apparatus I extends horizontally along the ground. The apparatus 1 is substantially as herein before described and the same reference numbers have been used to reference the common features.

The apparatus 1 comprises a tubular frame 4 that forms a railway track 82. The track 82 (as shown in Figure 6) comprises a fork junction 84. The sideways movement function of the present invention is used to direct the train 80 along one of the folk routes.

There follows a brief description of a operational methods steps for the train car 80 and apparatus 1 : 1. NO POWER-Primary members 28,29 have no power; the H-shaped laminate core is stopped and resting on the guides 18,20.

2. EMERGENCY MOVEMENT-Auxiliary onboard power supply 61 provides power to the lower auxiliary winding 59 to lift and move the vehicle to a railway track siding or to a part of the track that has power.

3. STOPPED-The onboard controller 62 has asked for power from the supply controller 66 to the primary members 28,29 in the required direction. A variable frequency three phase supply is fed to the primary members 28,29 at a low frequency in the required section of track 82. A braking device (not shown) holds the train 80 stationary. Current will be induced into the secondary windings 56,58 at slip frequency (slip frequency will equal primary member 28,29 frequency when stopped) the current is converted and fed into the

auxiliary windings 59 to give extra lift by inducing an equal and opposite force in the stationary lower windings 55.

4. TAKE OFF-The brakes are released, this allows the train 80 to move in the desired direction. The induced slip frequency decreases in floater windings 56,58 as the vehicle speeds up. The onboard controller 70 varies the current between the secondary windings 56, 58 and the auxiliary windings 59 to compensate for the loss of slip current and maintain lift. Controller 70 will also control the winding current flow to keep the vehicle central between the primary members 28,29. The onboard controller 70 asks the supply controller 66 to switch on the next part of the track at an increased frequency via controllers 68, inhibit the line in the distance and allow the track behind to be used by other vehicles.

5. CRUISE-The train 80 reaches the next section of track the train 80 will increase speed. The onboard controller 70 varies the current between auxiliary windings 59 to compensate for the change of slip current and maintain lift. The controller 70 will also control the winding 59 current flow to keep the vehicle central between the primary members 28,29. The onboard controller 70 asks the supply controller 66 to increase or decrease frequency to speed up or slow down to the desired speed, inhibit the fine in the distance and allow the track behind to be used by other vehicles.

6. STEERING-As the train 80 approaches a junction 84 the onboard controller alters the current in either side of the secondary windings 56,58, this tends to move the train to the left or right and move on to the left or right hand guide and a new section of track. As there will be a brief moment when only one primary drives the secondary and

auxiliary windings, the train 80 will need slow down to maintain lift and reduce mechanical friction. This should be the only time (apart from when there is no power and braking) that mechanical friction takes place.

7. BRAKING-The train will require a mechanical brake, however the main braking will be performed by making the secondary windings 56, 58 slip and dump all its energy into the auxiliary windings 59 (the auxiliary windings 59 will tend to drag down the speed if it not given a controlled current.

It will be appreciated by the skilled person in the art that the present invention may be adapted to provide vertical movement. Travelling vertically would be basically the same as horizontal movement only the vehicle would need an electrically energised fail safe brake and a mechanical fail safe brake, and possibly a brake driven from the onboard auxiliary power supply.

Travelling along a guide track in a vertical loop the loop may also be achievable under the present invention. This would again be the same as travelling horizontally and would have the same requirements as travelling vertically but it would require a gyroscopic passenger compartment.

Rotational movement may be achieved with the primary members arranged in a circle so they meet up with each other, giving continuos rotational movement.

By driving the H-shaped laminated core and feeding a DC current into the stationary secondary windings current will be induced into the primary member windings.

A frictionless bearing arrangement could be achieved by arranging the primary members in a circle so they meet up with each other, a shaft would pass through the centre the H-shaped core windings and would be attached to the shaft. An auxiliary winding would hold the shaft in space whilst it turned.

Claims

1. An apparatus for propelling an object, the apparatus comprising two linear induction motor assemblies each comprising a primary member and a secondary member the longitudinal axis of one linear induction motor being substantially parallel to the longitudinal axis of the other linear induction motor and one member of each linear induction motor assembly being attached to the object, a power supply for the linear induction motor assemblies, and control means for controlling the power.

2. An apparatus for propelling an object as claimed in claim 1, wherein the two linear induction motor assemblies are tubular linear induction motor assemblies.

3. An apparatus for propelling an object as claimed in claim 1 or claim 2, wherein each linear induction motor assembly comprises a substantially C-shaped secondary member.

4. An apparatus for propelling an object as claimed in any one of claims 1 to 3, wherein each tubular linear induction motor assembly comprises a moveable secondary member and a fixed primary member.

5. An apparatus for propelling an object as claimed in claim 4, wherein each moveable secondary member is attached to the object.

6. An apparatus for propelling an object as claimed in claim 4 or claim 5, wherein the fixed primary members comprise semi-circular laminated cores with three phase windings wound thereon.

7. An apparatus for propelling an object as claimed in any one of claims 1 to 6, wherein the secondary members preferably form a

substantially H-shaped laminated core comprising two windings, the arrangement being such that the two windings are positioned between the primary members.

8. An apparatus for propelling an object as claimed in claim 7, wherein the H-shaped laminated core forms auxiliary secondary member means the arrangement being such that in use the auxiliary secondary member means provides additional directional force and lift.

9. An apparatus for propelling an object as claimed in any one of the preceding claims, wherein the apparatus comprises means for guiding the object.

10. An apparatus for propelling an object as claimed in claim 9, wherein the means for guiding the object comprises a track.

11. An apparatus for propelling an object as claimed in claim 9 or claim 10, wherein the means for guiding the object comprises a network of tracks.

12. An apparatus for propelling an object as claimed in any one of the preceding claims, wherein the arrangement of the apparatus for propelling an object is such that in use the control means can independently vary the current flow in each of the secondary members in order to produce a movement of the object in a direction that is substantially perpendicular to the longitudinal axis of the secondary members.

13. An apparatus for propelling an object as claimed in any one of the preceding claims, wherein the control means comprises sensors for

measuring the movement of the object in a direction that is substantially perpendicular to the longitudinal axis of the secondary members.

14. A method for changing the direction of an object, said method using apparatus in accordance with any one of the preceding claims, the method comprising independently varying the current flow in a pair of secondary members of a linear induction motor assembly in order to produce a movement of the object in a direction that is substantially perpendicular to the longitudinal axis of the secondary members.

15. An apparatus for propelling an object substantially as herein described with reference to the accompanying drawings.

16. A method for changing the direction of an object substantially as herein described with reference to the accompanying drawings.