GB2240372A

GB2240372A - A gear position sensor

Info

Publication number: GB2240372A
Application number: GB9001745A
Authority: GB
Inventors: David Parsons; Alastair John Young
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1990-01-25
Filing date: 1990-01-25
Publication date: 1991-07-31
Anticipated expiration: 2010-01-25
Also published as: EP0513026A1; DE69023148D1; DE69023148T2; WO1991011638A1; KR0169952B1; ES2077840T3; KR920704047A; EP0513026B1; JPH05503984A; GB2240372B; JP2994034B2; GB9001745D0

Abstract

The gear position sensor is used to indicate that one of a plurality of gear ratios has been engaged in a change-speed transmission (12). The sensor (23) comprises a sensing transducer component (53) and a co-operable component (42). The component (42) is movable relative to the transducer in a first direction and a second direction transverse to the first direction into any one of a plurality of predetermined attitudes each of which corresponds to one of the ratios. The cooperation between the components (52, 42) enables the transducer (53) to provide a signal to indicate that a particular ratio has been engaged. The component (42) may be of cam-like form for cooperation with an operating finger (54) of the transducer (53).

Description

GEAR POSITION SENSOR This invention concerns a gear position sensor and also a transmission for a motor vehicle in which the transmission is provided with such a sensor.

Typically a motor vehicle transmission may be of a type comprising a change-speed gearbox having a plurality of gear ratios which are mutually exclusively engageable so that at any instant only one of the ratios can be engaged, a movable member which can be moved in first and second opposite directions and also a third and fourth opposite directions which are transverse to said first and second directions such that said member can be moved to any desired one of a plurality of predetermined positions each corresponding to the engagement of a respective one cf said gear ratios, and the movement of said member to a said pre-eetermlne; position causing the engagement of the corresponding gear ratio.

An object of the present invention is to provide a gear position sensor which will enable the engagement of ratios to be sensed.

According to tlic; invention there is provided a gear position sensor to indicate that a gear ratio or one of a group of ratios has been engaged in a change speed transmission, the sensor comprising a sensing component and a co-operable component one of which can be moved relative to the other in a first direction and a second direction transverse to the first direction into any one of a plurality of pre-determined attitudes each of which corresponds to one of the ratios or group of ratios, the co-operation between the components enabling the sensing component to provide a signal to indicate that a said ratio or group of ratios has been engaged.

Preferably, one of the components defines a cam-like surface for co-operation with the other component. The cam-like surface may comprise a plurality of surface portions which co-operate with the other component in the respective attitudes.

A plurality of the aforesaid surface portions may be spaced apart in the first direction of movement and a plurality of the said surface portions may be spaced apart in the second direction. The first and second directions of movement may comprise respective linear and rotational movements.

The aforesaid surface portions are preferably interconnected by a common surface which may extend in the first direction. The common surface may be in a form of a narrow linear path preferably parallel with the said first direction of movement. The other of said components which is preferably a linear transducer, may include a member such as an operating finger arranged to follow said common surface when relative movement occurs between the components in said first direction.

Where the aforesaid surface portions are spaced apart in said second direction, rotary movement in opposite senses from a mean position may permit co-operation between those surface portions and the other component.

Preferably, where the aforesaid common surface extends in said first direction, it lies at said mean position.

The aforesaid mean position may correspond to a neutral position of the transmission.

Conveniently, the co-operable component e.g., the component defining the cam-like surface, is the component which is movable into the said attitudes and the sensing component, in such a case, is preferably held stationary.

Conveniently, the sensing component can occupy a position on the transmission which is normally occupied by a reversing lamp switch.

Preferably the sensing component provides a signal which causes a releasable clutch to engage after the selected ratio or group of ratios is engaged but prior to operation of detent means in the change speed transmission which maintains the selected condition of the ratio or group of ratios.

Preferably the sensing component provides a signal which causes a releasable clutch to disengage after a selected ratio or group of ratios has been disengaged.

Normally, one of the engagement ratios will be a reverse ratio and the sensing component will provide an operating signal when reverse ratio is-selected which is used to cause a reversing indicator to operate. The operating signal which causes the reversing indicator to operate may be of a level different from the levels of signals provided by the sensing component when other ratios are selected.

As mentioned above one of the components may define a cam-like surface for co-operation with the other component in the respective attitudes. In such a case the surface portion which operates with the other component in an attitude which corresponds to reverse ratio may be arranged to create movement of part of the sensing component which will cause the sensing component to provide said different level of signal.

Preferably the amount by which the said part of the sensing component is moved when selecting reverse ratio is greater than that by which it is moved by other of the said surface portions when selecting other ratios.

The movable component may be movably mounted on a selector element which moves over a given distance to select the ratios. In such a case the movable component may be permitted to move with said selector element for a reduced distance less than said given distance. Preferably the selector element moves relative to the movable component up to said given distance after the movable component has moved through said reduced distance.

The selector element may be movable relative to said movable component against a resilient bias. In that case the resilient bias may be provided by a suitable spring.

The movable component may be formed with a bore which slidably receives the selector element to permit the selector element to move relative to the movable component. Conveniently, the spring may be arranged between a surface of the movable component in which the bore is formed and a surface of the selector element or a member fast therewith.

According to a second aspect of the invention, the is provided a transmission for a motor vehicle incorporating a gear position sensor according to the aforesaid first aspect of the invention or any of the consistory clauses relating thereto.

A gear position sensor in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Fig.1 is a cross-section through part of a change speed transmission of a vehicle and showing diagrammatically part of an engine and clutch, Fig.2 is a cross-section taken through a cam in Fig.l generally on the line II-II in Fig.1 and showing a gear selector arum, Figs.3 and 4 are further cross-sections through the cam on lines III-III and IV-IV in Fig.1, Fig.5 is a diagram of voltage output from a linear transducer at various positions of the cam, Fig.6 is a view similar to Fig.1 showing part of the transmission having its casing modified te re-pcsiticn a sensor, and Fig.7 is a diagram similar to that in Fig.5 showing voltage output resulting from use of the arrangement shown in Fig.6.

With reference to Fig.l of the accompanying drawings, an internal combustion engine 10 includes a semiautomatic transmission 12 for a motor vehicle (not shown). The transmission comprises a clutch 14, for example a diaphragm spring clutch, and a change speed gearbox 16 for supplying the rotary drive to one or more road wheels of the vehicle. The gearbox 16 comprises a plurality of mutually exclusively selectable gear ratios any desired one of which is selectable (in the course of a driver making a gear change) by suitable pre-determined manual movement of a gear shift lever 17 to disengage or de-select the said ratio currently engaged and then select or engage any desired said gear ratio. A clutch control for automatically engaging and disengaging the clutch comprises an electronic control 18 and a fluid control 19. The electronic control comprises computer means.

The clutch is disengaged and re-engaged using a release lever or fork 20 and interacting in known manner with the clutch. The rate and degree of engagement of disengagement of the clutch at any instant is controlled by the electronic control 18 and fluid control 19. The gear selection lever 17 may be of a kind described in our co-pending application No.PCT/GBB9/01199 and is not described in detail herein. The gear lever is sensitive to manual force applied to a knob 22 indicating a wish by the driver to change gear. The electronic control 18 operates in response to tilting of the knob 22 and provides an output clutch disengage signal causing the fluid control 19 to disengage the clutch 14.Thereafter, engagement of any desired gear ratio is observed by a gear position sensor generally indicated at 23 which provides a gear engagement completed signal to the electronic control 18 along a line 24. In response, the electronic control 18 provides an output re-engage signal to the fluid control 19 so as automatically to re-engage the clutch 14.

Fig.1 includes a typical shift pattern for the gear lever 17 in a gearbox having five forward ratios comprising first, second, third fourth and fifth ratios and one reverse ratio. Any desired one of such ratios can be engaged by moving the selection lever 17 to the positions 1, 2, 3, 4, 5 or R respectively in the gear shift pattern. When the gearbox is in neutral, the gear shift lever adopts position along path N.

The selection lever 17 is mechanically connected to one end of a selector arm 25 having its other end formed as a ball 26 pivotally mounted within a bearing 27 carried by a stationary casing part 28 of the gearbox 16. The arm 25 is pivoted intermediate its ends in a universal bearing 30 provided with gaiters 32 to prevent ingress of foreign matter into the bearing. The bearing 30 is carried by a lever 33 which is rotatably fast with a selector shaft 34 slidable and rotatable within bores 35, 36 defined by the casing part 28. The shaft 34 (constituting the aforesaid selector element) is arranged to operate selector forks (not shown) in the gearbox 16 for engaging selected ratios. A gaiter 31 extends between the selector shaft 34 and casing part 28.

The selector shaft 34 is drivably connected to a sleeve 37 by means of a drive pin 38. The sleeve 37 is formed with an outer groove 39 having parallel side walls 40 which slidably receive a cam member 42 constituting one of the aforesaid co-operable components. The cam member has upper and lower flanges 43, 44 formed with respective coaxial bores 45, 46 through which the selector shaft 34 slidably passes. A spring 47 extends between the sleeve 37 and flange 44 so as normally to bias the flange 43 downwardly against the upper end of the sleeve 37.

The cam member 42 provides an upper set of cam surfaces 48 as viewed in Fig.1 comprising two cam surfaces 48a, 48b extending from a central vertical path 49, a lower cam surface 50 connected to the path 49 and an intermediate set 51 comprising cam surfaces 51a, 51b extending each side of the path 49. The path 49 constitutes the aforesaid common surface.

The transmission casing part 28 is formed with a mounting 52 for a linear transducer 53 constituting the other of the aforesaid co-operable components. The transducer 53 has an operating finger 54 which is normally biased against the cam member 42. The linear transducer 53 is connected to the electronic control 18 through the line 24.

When the selector lever 17 is positioned in the neutral path N, the operating finger 54 lies on the path 49 of the cam member 42, the path occupying the aforesaid mean position.

To select reverse ratio, the selector lever 17 is moved to the extreme left as viewed in Fig.1 along the neutral path N thereby pivoting the selector arm 25 about its right hand end into its upper position in Fig.1. Such movement causes the lever 33, selector shaft 34 and cam member 42 to move upwardly in the aforesaid first direction relative to the linear transducer 53. The operating finger 54 then aligns on path 49 with the lower cam surface 50 and movement of the selector lever 17 towards the position R causes the selector arm 25 to pivot towards the position R in Fig.2 thereby rotating the selector shaft 34 and causing the operating finger 54 to engage the lower cam surface 50. Rotary movement of the selector shaft 34 constitutes movement in the aforesaid second direction.

The output from the linear transducer then provides an appropriate signal to the electronic control 18 and will be described below with reference to Fig.5.

To select ratio 1, the selector lever 17 is moved back into neutral, moved to the right along the neutral path N and then into the position 1. That movement causes the selector arm 25 to bring the cam member 42 back to the neutral position and to move the selector shaft 34 downwardly. In that way, the path 49 rides along the operating finger 54 before the selector shaft 34 is rotated further to cause the finger to engage cam surface 51a of the intermediate set of surfaces.

To select ratio 2, the gear selector lever 17 is moved across the neutral path N and then into position 2.

Such movement causes the selector shaft to rotate bringing cam surface 51b into contact with the finger 54.

To select ratio 3, the gear selector lever 17 is moved back into neutral so that the finger 54 engages path 49. The selector lever 17 is then moved to the right along the neutral path N and then into position 3.

Such movement rotates the shaft 34 causing the surface 51b to disengage finger 54, subsequently moves the shaft downwardly causing the path 49 to ride along the finger 54 and finally rotates the shaft 34 bringing surface 48a into contact with finger 54.

To selector ratio 4, gear selector lever 17 is moved across neutral and into position 4. Such movement causes the selector shaft 34 to rotate bringing the cam surface 48b into contact with finger 54.

In ratios 3 and 4, the flange 44 of the cam member engages or is positioned closely adjacent a surface 55 of the casing part 28.

To select ratio 5, the gear selection lever 17 is moved back into neutral so that the finger 54 engages the path 49. The selector lever 17 is then moved to the right along the neutral path N and then into position 5. Such movement rotates shaft 34 causing the surface 48b to disengage finger 54, and moves shaft 34 downwardly until the shaft 34 reaches its lowest position. As the flange 44 of the cam member 42 cannot move beyond the surface 55, the downward movement of the shaft 34 causes the spring 47 to compress.

Movement of the selector lever 17 into position 5 then rotates shaft 34 bringing surface 48a into contact with finger 54. Therefore it will be seen that in ratio 5 finger 54 engages the same surface 48a as in ratio 3.

However the angular movement of shaft 34 when selecting ratio 3 is slightly less than that when selecting ratio 5. Also, the angular movement of shaft 34 between neutral and the positions where ratios 2 and 4 are selected is greater than that between neutral and the positions where ratios 1, 3, 5 and R are selected. The lengths of the sets of cam surfaces 48, 49 and 51 in the rotational directions of the shaft are selected to accommodate such differences in angular movement.

In Fig.5 outputs from the transducer 23 can be seen for the selected ratios.

In Fig.5 the references 1, 2, 3, 4, 5, R and N correspond to the shift positions shown in Fig.1, the voltage output from the transducer 53 is indicated at and the rotational position of the selector shaft 4 each side of neutral position N is indicated at A.

As the gear selector lever 17 moves out of the neutral path N to select a ratio (e.g. ratio 1) with the clutch disengaged, the ratio will engage at point E1 before the selector lever moves fully home in position T1 where a gear selector detent (not shown) within the change speed transmission becomes operative to hold the transmission in ratio 1. As soon as E1 is reached the clutch re-engages in response to a signal Vb from the transducer 53. On reaching position T1 a voltage Vc is produced to indicate detent engagement. As the selector lever 17 is moved back towards the neutral path N, the ratio will disengage at a point D1 where a signal Vb is produced by the transducer which causes disengagement of the clutch to take place.A similar sequence occurs in the remaining ratios as apparent from the Fig.5 and the table below:

RATIO RATIO RATIO DETENT TRANSDUCER OUTPUT REQUIRED DISENGAGED ENGAGED ESX;;D VOLTS 1 Va El Vb T1 Vc 2 El Th Vc 3 D3 Vd 5 D5 Vd E5 Ve Va TR Vr When selecting reverse ratio R, the cam surface 50 causes the operating finger 54 to be moved a greater distance than when it is moved by the other cam surfaces. Such movement enables a greater output voltage signal to be obtained as the gear selector lever 17 moves towards its fully home position TR.

During such movement, the output voltage enters a range RL which is higher than voltage Vc and sufficient to enable the output voltage to operate, e.g., a power transistor or relay in the electronic control 18 so as to switch on a reversing lamp and/or other reversing indicator. Alternatively, the transducer 53 can include a switch which operates to switch on the reversing indicator as the gear lever moves towards the fully home position.

In Fig.1, the linear transducer 53 occupies a position normally occupied by a reversing lamp switch of the transmission. Therefore, the present invention is readily adaptable to an existing transmission where the cam member 42 can be easily positioned on the selector shaft 34 and the normal reversing lamp switch simply replaced by a linear transducer 53. Such an arrangement avoids the need to make any modifications whatsoever to the gearbox casing which is normally a casing. Such an arrangement is most advantageous in that respect.

Where the casing 28 can be modified to re-position the mounting to take the linear transducer 23 as in Fig.6, the cam member (indicated at 142) can be pinned directly to the selector shaft 34 and positioned so as to travel with the selector shaft 34 over its full axial travel distance. Such an arrangement avoids the need for a spring 47 as in Fig.1 where the cam member in that figure is unable to travel downwardly for the full downward travel distance of the selector shaft.

In Fig.6 the cam member is provided with a cam surface 150 for engagement with finger 54 in ratio 5. The cam surface 150 extends from one side of the path 49 such that the voltage outputs at Dg, E5 and T5 for ratio 5 will be the same as those at D3, E3 and T3 for ratio 3.

The outputs for the Fig.6 arrangement can be seen in Fig.7 and in the table below.

RATIO RATIO RATIO DETENT TRANSDUCER OUTFUT REQUIRED DISENMEED ESD E2GEED VOLTAGE 1 D1 Va E1 T1 Vc 2 D2 Va E2 Vb T2 Vc 3 D3 Vd El Ve T3 Vf 4 D4 vd Ve El T4 Vf 5 D5 Vd Ve Va R Vr In all other respects, the arrangement shown in Fig.6 is the same as that in Fig.1.

Instead of using the selector shaft 34 to select a particular ratio it may be arranged to select a particular group of ratios as in, for example, a range change gearbox.

Claims

1. A gear position sensor to indicate that a gear ratio or one of a group of ratios has been engaged in a change-speed transmission, the sensor comprising a sensing component and a co-operable component one of which can be moved relative to the other in a first direction and a second direction transverse to the first direction into any one of a plurality of predetermined attitudes each of which corresponds to one of the ratios or group of ratios, the co-operation between the components enabling the sensing component to provide a signal to indicate that a said ratio or group of ratios has been engaged.

2. A gear position sensor according to Claim 1 in which one of said components defines a cam-like surface for co-operation with the other component.

3. A gear position sensor according to Claim 2 in which the cam-like surface comprises a plurality of surface portions which co-operate with the other component in the respective attitudes.

4. A gear position sensor according to Claim 3 in which some of said surface portions are spaced apart in said first direction of movement.

5. A gear position sensor according to Claim 3 or 4 in which some said surface portions are spaced apart in said second direction.

6. A gear position sensor according to Claim 3, 4 or 5 in which the surface portions are interconnected by a common surface which extends in said first direction.

7. A gear position sensor according to Claim 6 in which the other of said components includes a member arranged to engage said common surface when relative movement occurs between said components in the first direction.

8. A gear position sensor according to Claim 7 in which movement in the first direction is linear.

A A gear position sensor according to any preceding Claim in which movement in the second direction is rotary.

10. A gear position sensor according to Claim 5 or to Claim 6, 7 or 8 when appendant to Claim 5 in which movement in the second direction is rotary, and rotary movement in opposite senses from a mean position permits co-operation between those surface portions and the other component.

11. A gear position sensor according to Claim 10 and where said common surface is provided, in which the common surface is arranged at said mean position.

12. A gear position sensor according to any preceding Claim in which the co-operable component is movable into said attitudes relative to the sensing component.

13. A gear position according to any preceding Claim in which the sensing component is a linear transducer.

14. A gear position sensor according to any preceding Claim in which the sensing component occupies a position on a transmission normally occupied by a reversing lamp switch.

15. A gear position sensor according to any preceding Claim in which the sensing component provides a signal which causes a releasable clutch to engage after the selected ratio or group of ratios is engaged but prior to operation of detent means in the change speed transmission which maintains the selected condition of the ratio or group of ratios.

16. A gear position sensor according to any preceding Claim in which the sensing component provides a signal which causes a releasable clutch to disengage after a selected ratio or group of ratios has been disengaged.

17. A gear position sensor according to any preceding Claim in which one of the engageable ratios is a reverse ratio and the sensing component provides an operating signal when reverse ratio is selected which is used to cause a reversing indicator to operate.

18. A gear position sensor according to Claim 17 in which the operating signal which causes the reversing indicator to operate is of a level different from the levels of signals provided by the sensing component when other ratios are selected.

19. A gear position sensor according to Claim 18 in which one of the components defines a cam-like surface for co-operation with the other component and the cam like surface comprises a plurality of surface portions which co-operate with the other component in the respective attitudes, the surface portion which cooperates with the other component in an attitude which corresponds to reverse ratio being arranged to create movement of part of the sensing component which will cause the sensing component to provide said different level of signal.

20. A gear position sensor according to Claim 19 in which the amount by which the said part of the sensing component is moved when selecting reverse ratio is greater than that by which it is moved by the other of the said surface portions when selecting other ratios.

21. A gear position sensor according to any preceding Claim in which the movable component is movably mounted on a selector element which moves over a given distance to select the ratios.

22. A gear position sensor according to Claim 21 in which the movable component is permitted to move with said selector element for a reduced distance less than said given distance.

23. A gear position sensor according to Claim 22 in which the selector element moves relative to the movable component up to said given distance after the movable component has moved through said reduced distance.

24. A gear position sensor according to Claim 23 in which the selector element is movable relative to said movable component against a resilient bias.

25. A gear position sensor according to Claim 24 in which the resilient bias is provided by a spring.

26. A gear position sensor according to any of Claims 21 to 25 in which the movable component is formed with a bore which slidably receives the selector element to permit the selector element to move relative to the movable component.

27. A gear position sensor according to Claim 26 when appendant to Claim 25 in which the spring is arranged between a surface of the movable component in which the bore is formed and a surface of the selector element or a member fast therewith.

28. A transmission for a motor vehicle incorporating a gear position sensor according to any preceding Claim.

29. A gear position sensor constructed and arranged substantially as described herein with reference to Figs.1 to 5 or Figs.6 and 7 of the accompanying drawings.