GB2281957A

GB2281957A - Rotational angle signal transmitter

Info

Publication number: GB2281957A
Application number: GB9418724A
Authority: GB
Inventors: Christian Bergmann; Klaus Maldener; Edgar Rapp; Erik Maennle
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1993-09-20
Filing date: 1994-09-16
Publication date: 1995-03-22
Anticipated expiration: 2014-09-16
Also published as: FR2710408A1; GB2281957B; GB9418724D0; DE4331902A1; JPH07164912A; FR2710408B1

Description

2281957 ROTATIONAL ANGLE SIGNAL TRANSMITTER The present invention relates

to a signal transmitter, in particular for the rotational angle of a vehicle accelerator pedal.

A known rotational angle transmitter, as described in DE 34 11 455 Al, comprises a transmitter shaft which is rotatably mounted in a housing and is rotatable by the accelerator pedal of a motor vehicle against a restoring spring arrangement. For detection of the pedal setting, the shaft co-operates with a rotary angle sensor which delivers an electrical signal corresponding to the pedal setting and thereby to the desired vehicle engine power.

In motor vehicles with automatic transmission, it is necessary to change down to a next lower gear for acceleration. For this purpose, an appropriate switching signal is needed. This signal is produced on pressing beyond (kickdown) a certain rotary angle by an electrical switching contact or on ascertaining of a certain rotary angle.

In order to avoid an unintended changing back, the electrical switching point must be preceded by a mechanical resistance, thus a clearly perceivable rise in the reaction force at the accelerator pedal. For this purpose, at least one sliding or rolling body, which co-operates with a running surface in the housing, at which the path of the body is fixed and which has a ramp arranged at a certain angle of rotation, is provided in a guide cage. When the body biassed towards the running surface is guided, against the bias, over the rising ramp from a first level to a second level, the increase in force required for this causes a mechanical resistance which is perceivable at the pedal and corresponds to the switching point.

2 The same, but now undesired, increase in force is perceivable on the return of the accelerator pedal and thereby on the return of the rolling body over the ramp.

According to a first aspect of the present invention there is provided a signal transmitter with a rotatably mounted shaft, which is rotatable by an accelerator pedal of a motor vehicle by way of gear means against the restoring force of a restoring spring arrangement and which co-operates with a rotary angle sensor delivering an electrical pedal value signal, a cage for at least one runner body, and a guide surface for the body, towards which this is resiliently biassed, wherein the cage and the guide surface are movable relative to each other by the shaft whilst determining a direction of the cage, and the guide surface has at least one ramp, which corresponds to a certain angle of rotation and by way of which the body is displaceable against the soring bias in the cage from a first portion, which determines a first level, of the guide surface to a second portion, which determines a second level, of the guide surface, characterised in that the body is mounted movably, parallelly to the guide surface, in the'cage.

A transmitter embodying the invention has the advantage that an increase in force is not perceivable during the return of the accelerator pedal. The movable mounting of the body has the result that the body during its return to the first level cannot transmit any force component acting in its direction of movement, thus in the direction of movement of the guide cage, and at the accelerator pedal. Thus, an improved feel of the pedal is made possible, whereby a gain in comfort is achieved in the handling of the vehicle.

Preferably, the body is mounted in the cage to be movable parallelly to the guide surface in its direction of movement. For preference the displacement path of the body in the cage in its directJon of movement is greater than 1.5 times the length of the body in the direction of movement of the cage.

In one preferred embodiment, the runner body is retained in the cage to be movable transversely to its direction of movement and a return surface,. which is secure against rotation relative to the guide surface and lies on the first level and by way of which the body can be brought to the first level transversely to the direction of movement of the cage and returned to the actual guide surface whilst bypassing the ramp, is provided beside the guide surface and displaced laterally to the path of the body over the ramp. In this case, too, the movable mounting of the body prevents an undesired transmission of force to the cage. Expediently, a guide trough by which the body can be brought onto the return surface, is provided in the second portion of the guide surface at a spacing from the ramp.

Preferably, the guide surface for the body is provided at a guide surface carrier of the metal. The guide trough, when present, can be provided in an insert of synthetic material in the carrier.

The carrier can be associated with a guide body of synthetic material, at which the return surface is formed and which has an inclined surface portion for the return of the body onto its actual path. For preference, the body is received in an elongate hole in the cage.

4 Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a partially sectioned schematic pian view of a first signal transmitter embodying the invention; Fig. 2 is a cross-section substantially along the line II II in Fig. 1; Fig. 3 is a set of diagrams showing different relative settings of a guide surface and cage of the transmitter on depression of a vehicle accelerator pedal operatively coupled to the cage; Fig. 4 is a set of diagrams showing different relative settings of the guide surface and cage on return of the pedal; Fig. 5 is a schematic perspective view of a part of a guide surface carrier and associated guide member in a second transmitter embodying the invention; Fig. 6 is a schematic plan view, in development, of the guide surface carrier 'and guide member of Fig. 5, and Fig. 7 is a cross-section substantially along the line VII-VII in Fig. 5.

Referring now to the drawings, there is shown in Fig. 1 a pedal value transmitter 10 with a housing 11, in which a transmitter shaft 12 is mounted to be rotatable. At an end 13 thereof projecting out of the housing 11, the shaft 12 carries an actuating lever 14, which is acted on in suitable manner by an accelerator pedal (not shown) of a motor vehicle in order to rotate the shaft 12 in the housing 11 in correspondence with the pdeal setting. ' A restoring spring arrangement 15, which is arranged co axially with the shaft 12 and comprises a first spring cage 16 and a second spring cage 17, which are connected secure against relative rotation with, respectively, the transmitter shaft 12 and the housing 11, is provided in the housing 11. Two parallelly acting restoring springs 18 and 19, which on rotation of the shaft 12 produce a reaction force acting on the accelerator pedal, are received in the spring cages 16 and 17.

A rotary angle sensor and possibly one or more switch contacts, which correspond to one or more certain rotary setting angles, are associated with the other end of the shaft 12, this end being situated in the housing 11. The sensor and the or each switch contact are connected by way of an electrical line 20, which is led, in sealed manner, out of the housing 11, with an electronic system of the vehicle.

In order to produce, during pressing (kickdown) of the accelerator pedal beyond a certain rotary angle, a mechanical resistance which is clearly perceivable at the pedal, a kickdown mechanical system 21 is arranged in the housing 11. This system comprises, as shown in Fig. 2, a guide cage 22, which is mounted secure against rotation of the transmitter shaft 12, for one or more sliding or rolling runner bodies 23, as well as a guide surface carrier 24 coaxial therewith. The bodies 23, which preferably are balls, are mounted in elongate holes extending circumferentially and are biassed radially outwardly towards a guide surface 27 at the carrier 24 by leaf springs 26., The surface 27 comprises one or more, for example three, ramps 28, which are uniformly distributed circumferentially and which each form a boundary between a respective first portion 29 and a respeptive second portion of the surface 27. The first port-ions 29 in that case lie on a first level which is displaced radially outwards relative to a second level of the second portions 30.

In case it is required to present several pressure points, thus a respective mechanical resistance at each of different preset rotary angles, the ramps 28 can have different circumferential spacings from each other.

As is apparent from Figs. 3 and 4, the length L of the elongate holes 25 is greater in circumferential direction, preferably greater than 1.5 times the corresponding dimension D, thus the diameter, of the balls serving as rolling bodies 23.

is The functioning of the described kickdown mechanism is explained in more detail below.

In Fig. 3, the movement of the cage 22 and body 23 relative to the guide surface 27 during kickdown of the accelerator pedeal is illustrated schematically, wherein the initial position is shown in the lefthand diagram and the final position in the righthand diagram. In corresponding manner, the return of the body 23 and cage 24 from the final setting back to the initial setting is shown in Fig. 4, in which case, however, the movement is illustrated from right to left.

As long as the rolling body 23 is travelling on the first portion 29 of the surface 27, the force K produced by means of the accelerator pedal need overcome only the restoring force of the restoring springs 18 and 19. As soon as the body 23, which lies against the trailing edge of the elongate hole 25, is guided over the ramp 28, it is urged by the ramp 28 against the force of the spring 26. The force f, which acts between the body 23 and the ramp 28 and parallel to the direction of movement of the cage 22, is transmitted from the body 23 to the cage 22.

To overcome this force f, an additional force k must be produced by the accelerator pedal, which force represents the desired mechanical resistance perceivable at the accelerator pedal.

Over the second portion 30 of the surface, only the restoring force of the restoring springs 18 and 19 then again acts against the further displacement of the cage 22.

When the body 23 is guided back from the second portion 30 by way of the ramp 28 onto the first portion 29 of the surface 27 during retraction of the accelerator pedal, as shown in Fig. 4, the leading portion of the hole 25 is already situated over the ramp 28, since the body 23 again lies against the trailing edge - previously the leading edge in the direction of movement shown in Fig. 3 - of the hole 25. As soon as the bearing surface of the body 23 reaches the ramp 28, the spacing of the leading edge of the hole 25 from the ramp 28 is already greater than the dimension D of the rolling body 23 in direction of movement. Consequently, a gap is formed between the leading edge of the hole 25 and the ramp 28, through which the body 23 can drop by way of the ramp 28 from the second portion 30 onto the first portion 29 of the surface 27 without transmitting a reaction force, which is caused by the spring 26 acting on it, to the cage 22.

Thus, only the restoring force produced by the restoring springs 18 and 19 of the restoring spring arrangement 17 is to be felt at the accelerator pedal, even when the body 23 is guided back over the ramp 28, during retraction of the accelerator pedal.

Figs. 5 to 7 concern another embodiment of the transmitter, in which a guide member 31, which preferably consists of a synthetic material, is arranged beside the guide surface carrier 24 and axially displaced thereto. The carrier 24, preferably consisting of metal, has a recess 32, into which an insert 33 with a guide trough 34 is inserted, in the region of the second portion 30 of the surface 27. The trough 34 is disposed at a spacing from the ramp 28.

The trough 34 is so arranged that it axially displaces the rolling body 23 (not illustrated in Fig. 5) situated on the second portion 30 at the second level and uides it back to the first level, in the instance defined by a return surface 25 which is provided at the member 31 and extends past the ramp 28 in circumferential direction. A guide surface 36, which extends obliquely to the axial direction and which displaces the body 23 axially without causing a radial displacement, is provided at the member 31 in the region of the first portion 29 of the guide surface 27.

As indicated in Fig. 6, the body 23 is guided in an elongate hole 25, which is inclined relative to the circumferential direction and to the axial direction, in the cage 22, which is not illustrated in Figs. 5 to 7. However, the outline of the elongate hole 25 in the cage 22 is illustrated in Fig. 6.

For production of the mechanical resistance on kickdown of the accelerator pedal, the body 23 is guided along its actual path B on the surface 27, whereby it passes from the first portion 29 by way of the ramp 28 to the second portion 30 of the surface 27. The body 23 in that case cannot leave the surface 27, since it is kept in contact with the trailing edge of the hole 25, which lies in the region of the surface 27.

As soon as the body 23 has reached the trough 34, it is displaced by the spring force of the spring 26 acting thereon along the path B' onto the surface 35. The body 23 is thus guided back to the first level transversely to the direction of movement of the cage 22.

On retraction of the pedal, the body 23 runs along the path B'' on the surface 35 and thus is situated on the level of the first portion 29 of the surface 27 at the carrier 24. After it has pssed by the ramp 28, the body 23 is guided by the surface 36 along the path B back to the portion 29 of the surface 27. In this manner, the body 23 can be brought back into its initial position without imposing a disturbing reaction on the pedal force.

It is particularly advantageous in this embodiment that the body 23 is constantly held in contact with the various surfaces in radial direction, whereby clicking or other disturbing noises due to dropping of the body 23 in the case of the first-mentioned embodiment can be avoided.

In the illustrated embodiments, the cage 22 and the springs 26 are connected secure against relative rotation with the shaft 12, so that pivotation of the shaft about its rotationasl axis causes pivotation of the cage 22 and the springs 26. However, embodiments are possible in which the cage is connected with the housing and the guide surface for the body 23 is connected with the shaft, so that on pivotation or rotation of the shaft the guide surface is likewise pivoted or rotated.

Claims

- 11 CLAIMS

1. A signal transmitter comprising a shaft connectible to a vehicle accelerator pedal to be rotatable, in use, by such pedal against a restoring force, a rotational angle sensor co-operable with the shaft to provide a signal indicative of the rotational angle thereof, and resistance means for providing a transient additional resistance to rotation of the shaft past a predetermined rotational angle, the resistance means comprising a guide surface having a ramp portion between two further portions disposed at respectively different levels, a runner body, biassing means to urge the body against the guide surface, and a cage retaining the body, the cage and guide surface being relatively movable by rotation of the shaft thereby to cause the body to run along the guide surface at least in a given direction of the shaft rotation and the surface portions being so arranged that on rotation of the shaft in the given direction past the predetermined angle the body travels over the ramp portion thereby to produce the resistance, the body being movable in the cage parallelly to the' guide surface to prevent the resistance occurring on rotation of the shaft in the direction opposite to the given direction.

2. A transmitter as claimed in claim 1, wherein the body is movable in the cage in the direction of relative movement of the guide surface and cage.

3. A transmitter as claimed in claim 2, wherein the body is movable in the cage over a path greater than one-and-a-half times the dimension of the body in the direction of relative movement of the guide surface and cage.

4. A transmitter as claimed in claim 1, wherein the body is movable in the cage transversely to the direction of relative movement of the guide surface and cage and the resistance means further comprises a return guide which is stationary relative to and disposed alongside the guide surface and which is arranged to guide 10 the body past the ramp portion of the guide surface on rotation of the shaft in said opposite direction past the predetermined angle and to then return the body to the guide surface.

5. A transmitter as claimed in claim 4, wherein the portion of the guide surface following the ramp portion with respect to the is movement of the body in the given dIrection of shaft rotation is provided at a spacing from the ramp portion with a trough to guide the body to the return guide.

6. A transmitter as claimed in any one of the preceding claims, wherein the guide surface is provided at least in part on a metallic 20 member.

7. A transmitter as claimed in claim 6 when appended to claim 5, wherein the trough is provided on a member of synthetic material inserted into the metallic member.

8. A transmitter as claimed in claim 4, wherein the return guide is of synthetic material and has a first surface portion to guide the body part the ramp portion of the guide surface and a second, inclined surface portion to cause the body to be returned to the guide surface.

9. A transmitter as claimed in any one of the preceding claims, wherein the body is located in an elongate recess in the cage.

10. A transmitter as claimed in any one of the preceding claims, wherein the body is a ball.

11. A transmitter as claimed. in any one of the preceding claims, wherein the resistance means comprises a plurality of such guide surfaces, a plurality of such bodies and respective biassing means to urge each body towards a respectively associated one of the guide surfaces, the bodies being retained in the same cage and disposed at 15 spacings from one another.

12. A transmitter as claimed in claim 11, wherein the resistances produced by the bodies on travel over the ramp portions of the associated guide surfaces occur at respectively different predetermined rotational angles of the shaft.

13. A transmitter substantially as hereinbefore described with reference to the accompanying drawings.

14. A vehicle provided with an accelerator pedaland with a transmitter as claimed in any one of the preceding claims connected to the shaft of the transmitter.

15. A vehicle as claimed in claim 14, wherein the transmitter is connected to the shaft by way of gear transmission means.

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