GB2109568A - Measuring torque on a vehicle wheel - Google Patents

Abstract

The apparatus comprises a torque member (13) surrounding a torque shaft (14) and engaged thereto by splines (17) and a locking bolt (16) at one axial end. At the other axial end, the torque member has a radial flange (12) to which a roadwheel (10) is attached, and the torque shaft has a radial flange (115) which is secured via an adaptor plate (19) to a wheel hub. Bearings (26) between the torque member and torque shaft transmit weight acting from the roadwheel (10) to the torque shaft and also take side forces so that the torque member is distorted only by torque. Torque is detected by strain gauges (25), and radio signals representative of the torque in the torque member are transmitted to a radio receiver, suitably located in the vehicle. The radio transmitter forms part of the torque unit which is attached to the roadwheel. In another embodiment, the torque member is a radial steel bar to which strain gauges are attached. <IMAGE>

Description

SPECIFICATION Apparatus useful for measurement of torque at the roadwheel of a wheeled vehicle The present invention relates to apparatus usefui for measurement of torque at the roadwheel of a wheeled vehicle.

The determination of torque at the roadwheel of a wheeled vehicle is of some importance in evaluating the performance of the components of the vehicle concerned with driving and stopping the rotation of the roadwheel and/or also with fuel and lubricants involved in such rotation.

A common instance where the torque at the roadwheel is of interest is in connection with evaluating the quality of gasoline employed to power an internal combustion engine of a car.

Some evaluation tests for gasoline quality and the latter's influence on torque are sometimes investigated employing experienced car drivers, and their rating of the performance of a vehicle using a particular fuel is expressed in terms of "drivability". Drivability is the subjective evaluation of vehicle performance. Changes in torque at the road wheels of a car are the basis for the assessment of drivability, and it is an object of the present invention to provide apparatus by which the torque at the roadwheel of a wheeled vehicle can be detected and/or indicated and/or determined and/or recorded relatively objectively.

Apparatus for the measurement of torque is already known. One known apparatus employs equipment fixed to a suitable part of the engine or transmission system of the vehicle with wiring or slip ring units to recover the torque measurement parameters. Another known apparatus employs strain gauges disposed on the spokes of a roadwheel. A drawback of these known apparatuses is that they must be installed as a relatively permanent part of the vehicle so that every torque test must be performed on a vehicle which has been adapted in a relatively permanent manner so as to be capable of being used in a torque test.In yet another known apparatus, the torque measuring system includes a part which is either permanently attached to the wheel of a vehicle or permanently attached to an axle or hub of the vehicle so that the apparatus can be used only with a particular wheel and/or with a particular vehicle thereby reducing the utility of the apparatus and increasing costs since each vehicle must be provided with one apparatus.

Moreover, particular difficulty has heretofore been experienced in reliably recovering torque measurement parameters.

The apparatus of the present invention is intended to avoid at least some of the drawbacks of known apparatus, and the apparatus according to the invention comprises a unit adapted to be detachably attached between the roadwheel of a wheeled vehicle and a roadwheel mounting member of the vehicle, the unit comprising at least one torque-responsive strain gauge arranged so that the strain in the strain gauge is dependent on the torque applied to (or by) the roadwheel, means for detecting and/or indicating and/or determining and/or recording the strain in the strain gauge, and a radio transmitter operable to transmit signals representative of strain in the said strain gauge.

The unit preferably comprises a source of electrical power (e.g. an electric battery) for operating the radio transmitter, and may also operate other electrical equipment for processing strain signals obtained from the strain gauge.

The dimensions of the unit at locations between the roadwheel and its mounting member are preferably relatively small so that the roadwheel is displaced axially away from its mounting member by only a small distance.

Accordingly, the performance of the vehicle is substantially unaffected by the presence of the unit.

The apparatus preferably comprises a radio receiver operable for receiving strain-responsive radio signals from the said unit. The radio receiver is preferably associated with the vehicle (e.g.

within the vehicle), and there may be means for indicating and/or recording data relating to torque, which means may also be associated with the vehicle.

The unit may comprise a torque transmitting shaft which is mechanically engageable in relation to the said roadwheel mounting member, a torque member coaxial with the torque shaft and having a radial flanged part for the attachment thereto in a predetermined radial plane of a roadwheel, the said strain gauge(s) being operatively mounted on the said torque member, bearings rotatably supporting the torque member relative to the torque shaft, said bearings being in radial planes substantially including the said predetermined radial plane to transfer radial (and, optionally, axial) forces from the torque member to the torque shaft, and attaching means for detachably attaching the torque member to the torque shaft. Preferably, the torque member is detachably attachable to the torque shaft in such a manner as to be radially outwards (e.g. at least partly surrounding) of the torque shaft.

The apparatus may comprise an adaptor plate having a frusto-conical aperture which, in use, normally diverges towards the said mounting member and which cooperates with a corresponding frusto-conical outer part of the torque shaft, and means for detachably securing the adaptor plate to the mounting member so that the cooperation of the said frusto-conical surfaces engages the torque shaft with the adaptor plate in an axial and rotational sense.

In another type of embodiment, the unit may comprise an adaptor for engaging one side of the unit to the mounting member, a wheel plate on which the roadwheel is attached to the unit in one radial plane, bearings disposed in said one radial plane for rotatably supporting the wheel plate relative to the adaptor and for transferring at least radial forces from the wheel plate to the adaptor, a torque member on which at least one strain gauge is mounted, first fastening means connecting the torque member to the adaptor at one radial distance from the central axis of the unit and second fastening means connecting the torque member to the wheel plate at a second, different, radial distance from the said central axis, the said strain gauge(s) being located at a radial distance between the first and second radial distances.

The torque member is preferably located in a substantially radial planes of the unit, and may comprise a substantially straight radially extending metal bar.

The unit may define a substantially cylindrical space radially inwardly of, and coaxial with, the bearings for receiving electrical equipment which is selected from at least one of the following: an electric battery, means for processing strain signals obtained from the strain gauge(s), and the radio transmitter.

The unit may comprise a tube which defines the said space, said tube being attached at one end region to the adaptor and having the other end region at leastly partly received radially inwardly of the said bearings.

The apparatus preferably comprises an electrical battery received within the tube.

The said other end region of the tube may protrude outwardly of the outer radial plane of the wheel plate.

At least some of the electrical equipment for processing strain signals from the strain gauge(s), and the radio transmitter are preferably mounted within said tube and/or around the periphery of the protruding end region thereof.

Preferably, substantially no part of the unit protrudes outwardly beyond the radial plane of the outer face of a tyre mounted on the said roadwheel when the roadwheel is attached to the unit.

The unit preferably comprises safety fastening members extending substantially parallel to the axis of the unit and connecting a radially outer region of the wheel plate to a radially outer region of the adaptor, said fastening members engaging the wheel plate and the adaptor in such a manner as to permit limited relative movements of the wheel plate and adaptor.

Preferably a peripheral region of the wheel plate and/or a peripheral region of the adaptor has a flange which surrounds the torque member, there being a sealing ring of relatively soft, resilient material which closes a gap defined between adjacent radial face(s) of the said peripheral regions to prevent or hinder the entry of water and debris into the said space surrounded by said flange(s) and said sealing ring.

The invention also comprises a vehicle provided with apparatus as described above.

The invention is now further described, by way of non-limitative examples, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a part-sectional view of one embodiment showing the principal features of a torque unit mounted at the hub of a roadwheel of a car; Figure 2 is a part-sectional view showing the principal features of another embodiment of a torque unit mounted at the hub of a roadwheel of a car, and Figure 3 is a diagrammatic elevation of a torque member used in the torque unit of Figure 2.

Referring to Figure 1 of the drawings, there is shown the radially inner part of the roadwheel 10 which is attached by set bolts 11 (only one of which is shown) to a radial flange 12 at one end of, and integral with, a hollow, a tubular torque member 1 3. A torque shaft 14 is concentrically received within the hollow torque member 13 and is attached to an inturned flange 14 at one axial end of the member 13 by a threaded stud and nut 1 6. The inturned flange 1 5 has splines in which splines 1 7 on the shaft are received so as to engage the shaft 14 and member 13 in a rotationaly sense.The torque shaft 14 is formed with a radially flanged part 1 5 at its other axial end, and the outer surface 18 of the flanged part 1 5 is frust-conical and divergent away from the inturned flange 1 5 and towards the drive hub (not shown) to which the roadwheel 10 is normally attached. An adaptor plate 19 having an aperture 20 therethrough which is frusto-conical in the same sense as the surface 1 8 of the flange is attached to the drive hub by bolts 21 (only one bolt is shown in the drawing), and the resulting cooperation of the frusto-conical surfaces 1 8, 20 engages the flange 15 of shaft 14 to the drive hub via the adaptor plate 19 in an axial sense. Socket grub screws 23 (only one is shown) engage the flange 1 5 and the adaptor 1 9 in a rotational sense.The torque member 1 3 is rotatably supported relative to the torque shaft 14 by bearings 26 which are so positioned as to convey weight components from the roadwheel to the torque shaft 14 and to remove side thrusts so that the torque member 13 is substantially free of the influence of weight and side thrusts.

Between the out-turned radial flange 12 of the torque member 13 and the radially inturned flange 1 5 thereof, the torque member has an annular groove 24 formed on its outer surface, and on the inner surface of the torque member 13, radially inwardly of the groove 24, are a plurality of strain gauges 25.

When power is applied to rotate the drive hub, the turning force is conveyed to the roadwheel via a unit comprising the adaptor plate 19, the torque shaft 14 and the torque member 13 (instead of directly to the roadwheel from the hub). The torque at the groove 24, where the thickness of the torque member 13 is reduced, is manifested as an increased strain which is detected by the strain gauges 25. The strain gauges 25 are arranged as an electrical network giving an electrical output which is representative of the strain. The electrical network may be of the Wheatstone bridge type.

A hollow tube 27 surrounds the right-hand (as shown) part of torque member 13 and is secured thereto by a plurality (e.g. three) of radial screws 28 (only one screw 28 is shown in the drawing).

The right-hand end of the tube 27 is closed by a cap 29 having a knob 30, and 'O'-rings 31 prevent the ingress of water and dust. The space 32 between the right-hand end of the torque member 1 3 and the cap 29 contains electrical circuitry for processing the strain signals from the strain gauges 25 to produce a signal representative of the torque in the torque member 13.

On the exterior of the hollow tube 27 are mounted battery boxes (not shown) to provide electrical power and a radio transmitter (not shown) which transmits the torque-representative signal by standard FM radio techniques. A radio receiver (not shown), which may for convenience be located in the vehicle, receives the FM signals and the decoded signals are indicated (e.g.

displayed) and/or recorded and/or determined in any convenient form.

Reference is now made to Figure 2 which shows a torque unit 5Q detachably attached between a road wheel 51 of a vehicle (not shown) and a drive hub 52 (or other roadwheel mounting member of a vehicle).

The unit 50 comprises an adaptor 53 which abuts the drive hub 52 and is engaged therewith by bolts 52 (or equivalent means such as studs or set-screws, not shown). The adaptor 53 may be of cadmium plated mild steel.

A tube 55 is attached to the adaptor 53 so as to be co-axial with the axis of rotation 56 of the drive hub 52 and extends away from the drive hub 52. The tube 55 has a collar or flange 57 on its exterior which abuts against the outer face of the adaptor 53 and is secured thereto by bolts (not shown). The adaptor 53 has a central bore or hole 58 in which the inner end of the tube 55 is received. The inner end of the tube 55 may be a push-fit (e.g. a taper fit) in the hole 58 or it may have external screw threads (not shown) which engage internal screw threads (not shown) formed on at least part of the internal surface of the hole.

The tube 55 is formed or provided with a shoulder 59, and an annular needle bearing assembly 60 is received on the outside of the tube 55 abutting against the shoulder 59. The needle bearing assembly 55 is substantially in the central radial plane of the wheel 51 so as to receive vertical loads from the wheel 51. An annular wheel mounting plate 61 is disposed around the outer side of the needle bearing assembly 61. The wheel plate 61 is formed or provided with an annular flange 62 at its peripheral region, the flange extending towards the corresponding peripheral region of the adaptor 53, and defining therewith a narrow annular gap 63 having a width of the order of 0.03 to 0.08 mms (or thereabouts).The adjacent radial faces of flange 62 and the adaptor 53 are formed with a recess in which is received a sealing ring 64 of soft, resilient material (polytetrafluoroethylene, PTFE, available from Du Pont under the trade name "Teflon" may be used). It will be seen that the adaptor 53, the flange 62 and the wheel plate 61 (inter alia) define a volume into which water and debris are substantially prevented from entering.

The road wheel 51 is secured to the outer face of the wheel plate 61 inwardly of the peripheral region thereof by conventional studs (not shown) or set bolts 65 at the normal radius from the central axis of the roadwheel 51.

The wheel plate 61 is secured in relation to the adaptor 53 by safety bolts 66 at a radial distance which is between the said peripheral regions and the set bolts 65. The safety bolts 66 are arranged to permit limited relative movement of the wheel plate 61 and the adaptor 53 by having their opposite ends received in respective relatively large holes 67, 68, there being relatively soft, resilient rubber bushes 69, 70 around the respective ends within the holes 67, 68. The bolts are tensioned by securing fastening nuts 71 until the desired annular gap 63 is attained or approximately attained.

The needle bearing assembly 60 is maintained abutted against the shoulder 55 by a retaining ring 72 which is secured by bolts (not shown) to the outer face of the wheel plate 61.

Within the volume defined by the adaptor 53, the flange 62 and the wheel plate 61 is a torque member 73.

As will be seen by reference to Figs. 2 and 3, the torque member 73 comprises two substantially straight bar portions 74 extending radially outwardly from a central annular ring portion 75.

The bar portions 74 and ring portion 75 are integral with each other and may be formed of stainless steel. The internal diameter of the hole through the ring portion is greater than the external diameter of the tube 55 so that the torque member 73 can be received around the tube 55 with a clearance which will avoid contact between the torque member 73 and the tube 55 during normal use. The torque member has radially inner and outer bolt holes 76, 77 on each bar portion 74, and a strain gauge 78 is attached to each bar portion between the respective inner and outer bolt holes.

A bolt 79 extends through each outer bolt hole 77 parallel to the central axis 56 of the unit into an internally threaded bore or hole 80 in the adaptor 53 and a collar 81 around the bolt 79 serves as a spacer whereby the radially outer end of each bar portion 74 is located at substantially a predetermined distance from the adaptor 53.

A bolt 82 extends through each inner bolt hole 76 parallel to the central axis 56 of the unit into an internally threaded hole 83 of the wheel plate 61. If desirable, a collar (not shown) may be provided around each bolt 82 to serve as a spacer between the bar portion 74 and the wheel plate 61.

An electric battery (not shown) is located within the tube 55, and around the end region 81 of the tube 55 which protrudes outwardly away from the drive hub 52, there is provided an annular container 82 containing electrical equipment (not shown) for processing strain signals received from the strain gauges 78 and a radio transmitter (not shown) for transmitting radio signals representative of the processed strain signals to a radio receiver (not shown) which may be in the vehicle having the drive hub 52 or in another vehicle or other receiving station.

Strain signals are conducted by wires (not shown) from the strain gauges 78 to the equipment of the container 82 which is powered from the electric battery. The open end 83 of the tube 55 is closed by a cap member (not shown).

In order to use the torque unit 50 on an automobile, the set bolts 65 (or other conventional fastening means) which normally secure the wheel 51 to the drive hob 52 are removed and the wheel 51 is removed from the drive hub. The torque unit 50, complete with the electric battery and electrical equipment and radio transmitter, is then attached to the drive hob 52 by bolts 54 which are received in the same holes as are the set bolts 65, and the wheel 51 is then attached by the set bolts 65 to the wheel plate 61 of the torque unit. The wheel 51 is thus axially offset from its normal position by only a small distance (e.g. 4 to 12 cms) due to the narrow axial extent of the unit. The weight and other vertical loads acting on the unit 52 are taken out by the needle bearings 60 thereby avoiding distortion of the torque member 73 from these causes.Side thrusts, e.g. due to turning of the vehicle, acting on the wheel 51 are taken out via the annular flange 62, the sealing ring 64 and the adjacent peripheral region of the adaptor 53. Thus the torque member 73 is substantially insulated from vertical and side loadings acting on the wheel 51.

When the drive hub 52 is driven or braked, its torque is transmitted to the adaptor 53 and subsequently acts via bolts 79 on the torque member 73 which drives or brakes the wheel plate 61 and the wheel 51 via bolts 82. Torque in the torque member 73 alters the strain in the strain gauges 78 and radio signals representative of the torque are transmitted to a radio receiver and suitable recording and indicating means (not shown).

It will be appreciated from the foregoing that the torque unit of the invention is readily emplaced and removed on any vehicle without substantially affecting the performance of the vehicle on which it is used, and that torque signals are readily obtained from the torque unit during use. This contrasts with previous torquemeasuring units which tended to alter the characteristics of the vehicle in which they were used and/or were more or less permanently fixed in the vehicle and/or required relatively complicated systems for recovering torquerepresentative signals.A further benefit of the torque unit of the invention is that it can be employed on more than one vehiclezalthough the adaptor 53 might need to be changed for different arrangements of wheel-fastening studs or bolts on different vehicles, and vehicles generating relatively large torques might need different torque members 73 to vehicles generating relatively small torques. The simplicity, relative small dimensions, adaptability and inherent reliability of the torque unit of the invention provide benefits which have not previously been available in the field of measuring torque on vehicles.

The apparatus of the invention can be employed on virtually any wheeled vehicle for torque measurement with only very minor, and generally inconsequential, axial displacement of the roadwheel axially outwards from its normal position relative to the drive hub. The torque unit is easily attached and removed and one apparatus of the invention can be employed for many vehicles, thereby reducing costs and also improving the repeatability of the torque measurements obtained therewith.

Claims (24)

Claims

1. Apparatus for use in detecting and/or indicating and/or determining and/or recording torque at a roadwheel of a wheeled vehicle comprising a unit adapted to be detachably attached between the roadwheel and a roadwheel mounting member of the vehicle, the unit comprising at least one torque-responsive strain gauge arranged so that the strain in the strain gauge is dependent on the torque applied to (or by) the roadwheel, means for detecting and/or indicating and/or determining the strain in the strain gauge, and a radio transmitter operable to transmit signals representative of strain in the said strain gauge.

2. Apparatus as in claim 1 in which the unit comprises a source of electric power for operating the transmitter.

3. Apparatus as in claim 1 or claim 2 comprising a radio receiver operable for receiving strain-responsive radio signals from said unit.

4. Apparatus as in claim 3 in which the radio receiver is associated with the vehicle.

5. Apparatus as in any one of claims 1 to 5 in which the unit comprises a torque transmitting shaft which is mechanically engageable in relation to the said mounting member, a torque member coaxial with the torque shaft and having a radial flanged part for the attachment thereto in a predetermined radial plane of a roadwheel, the said strain gauge(s) being operatively mounted on the torque member, bearings rotatably supporting the torque member relative to the torque shaft, said bearings being in radial planes including the said predetermined radial plane to transfer radial and axial forces from the torque member to the torque shaft, and attaching means for detachably attaching the torque member to the torque shaft.

6. Apparatus as in claim 5 in which the said attaching means detachably attaches the torque member to the torque shaft at a position remote from the position at which the torque shaft is mechanically engageable in relation to the said mounting member.

7. Apparatus as in claim 5 or 6 in which the torque member is detachably attachable to the torque shaft in such a manner as to be radially outwards of the torque shaft.

8. Apparatus as in any one of claims 5 to 7 in which the torque member and the torque shaft are detachably attachable in the axial sense by a threaded stud or bolt and in the radial sense by splines or keys and keyways.

9. Apparatus as in any one of claims 5 to 8 comprising an adapter plate having a frustoconical aperture which, in use, normally diverges towards the said mounting member and which cooperates with a corresponding frusto-conical outer part of the torque shaft, and means for detachably securing the adapter plate to the mounting member so that the cooperation of the said frusto-conical surfaces engages the torque shaft with the adaptor plate in an axial and rotational sense.

10. Apparatus as in any one of claims 1 to 4 in which the unit comprises an adaptor for engaging one side of the unit to the mounting member, a wheel plate on which the roadwheel is attached to the unit in one radial plane, bearings disposed in said one radial plane for rotatably supporting the wheel plate relative to the adaptor and for transferring at least radial forces from the wheel plate to the adaptor, a torque member on which at least one strain gauge is mounted, first fastening means connecting the torque member to the adaptor at one radial distance from the central axis of the unit and second fastening means connecting the torque member to the wheel plate at a second, different, radial distance from the said central axis, the said strain gauge(s) being located at a radial distance between the first and second radial distances.

11. Apparatus as in claim 10 in which the torque member is located in a substantially radial planes of the unit.

12. Apparatus as in claim 10 or claim 11 in which the torque member comprises a substantially straight radially extending metal bar.

13. Apparatus as in any one of claims 10 to 12 in which the unit defines a substantially cylindrical space radially inwardly of, and coaxial with, the bearings for receiving electrical equipment which is selected from at least one of the following: an electric battery, means for processing strain signals obtained from the strain gauge(s), and the radio transmitter.

14. Apparatus as in claim 13 in which the unit comprises a tube which defines the said space, said tube being attached at one end region to the adaptor and having the other end region at leastly partly received radially inwardly of the said bearings.

1 5. Apparatus as in claim 14 of claim 1 5 comprising an electrical battery received within the tube.

16. Apparatus as in claim 14 or claim 1 5 in which the said other end region of the tube protrudes outwardly of the outer radial plane of the wheel plate.

1 7. Apparatus as in claim 16 in which at least some of the electrical equipment for processing strain signals from the strain gauge(s), and the radio transmitter are mounted within said tube and/or around the periphery of the protruding end region thereof.

18. Apparatus as in any one of claims 10 to 17 in which no part of the unit protrudes outwardly beyond the radial plane of the outer face of a tyre mounted on the said roadwheel when the roadwheel is attached to the unit.

1 9. Apparatus as in any one of claims 10 to 18 comprising safety fastening members extending substantially parallel to the axis of the unit and connecting a radially outer region of the wheel plate to a radially outer region of the adaptor, said fastening members engaging the wheel plate and the adaptor in such a manner as to permit limited relative movements of the wheel plate and adaptor.

20. Apparatus as in any one of claims 10 to 19 in which a peripheral region of the wheel plate and/or a peripheral region of the adaptor has a flange which surrounds the torque member, there being a sealing ring of relatively soft, resilient material which closes a gap defined between adjacent radial face(s) of the said peripheral regions to prevent or hinder the entry of water and debris into the said space surrounded by said flange(s) and said sealing ring.

21. Apparatus as in any one of claims 9 to 20 comprising screw-threaded means for engaging the adaptor plate with the torque shaft.

22. Apparatus as in any one of claims 1 to 21 comprising a plurality of torque-responsive strain gauges forming part of an electrical network.

23. Apparatus for use in detecting and/or indicating and/or determining and/or recording torque at a roadwheel of a wheel vehicle substantially as hereinbefore described.

24. Apparatus as in claim 23 substantially as described with reference to Figure 1 or Figure 2 of the accompanying drawing.

24. Apparatus as in claim 23 substantially as described with reference to Figure 1 or Figure 2 of the accompanying drawing.

25. The combination comprising a wheeled vehicle and apparatus as in any one of claims 1 to 24 in which the said unit is detachably attached between a roadwheel and a roadwheel mounting member of the vehicle.

26. The combination of claim 25 in which the said radio receiver is disposed in or on the vehicle for receiving strain-representative radio signals from said unit.

27. The combination of claim 26 comprising means for detecting and/or indicating and/or determining and/or recording strainrepresentative signals.

28. The combination of claim 27 in which the said means is disposed in or on the vehicle.

29. The combination of any one of claims 25 to 28 substantially as hereinbefore described.

New claims or amendments to claims filed on 25th January 1983.

Superseded claims 7, 17 and 24.

New or amended claims:

7. Apparatus as in claim 5 or claim 6 in which the torque member is detachably attachable to the torque shaft in such a manner as to be radially outwards of the torque shaft.

1 7. Apparatus as in claim 16 in which at least some of the electrical equipment for processing strain signals from the strain gauge(s), and the radio transmitter are mounted within said tube and/or around the periphery of the protruding end region thereof.