This invention relates to a vehicle speed control device.

Many countries have imposed a maximum vehicle speed limit, and a number of vehicle speed limiting devices intended to help prevent the driver from inadvertently exceeding that speed limit have been proposed. Some of the known speed limiting devices operate to over-ride the accelerator pedal, and such devices can usually be adjusted by the driver, to alter the pre-set maximum speed.

For long distance driving, other devices have been proposed which permit "cruise control", whereby the vehicle speed is generally held within a pre-set range. Typically the device has a first mode in which the maximum speed in general is automatically held at or below a pre-set maximum, and it has also a second mode in which the vehicle speed in general is held at or above a pre-set minimum; the device in this second mode again over-rides the accelerator, but so as to effect an increased fuel flow to the engine to raise the vehicle speed to within the pre-set range.

Vehicle speed control devices of the type with which this invention is concerned are typically interposed in the linkage between an accelerator pedal and the vehicle carburetter (for a petrol engine) or pump (for a diesel engine); though for vehicles

having a hand-operated accelerator lever or equivalent it will be interposed between such lever and e.g. the carburetter.

Thus according to one feature of the invention we propose a vehicle speed control device which includes a first transmission 5 unit, a second transmission unit, coupling means adapted to interconnect the transmission units for movement together, and control means to effect relative movement between the units characterised in that the coupling means comprises a first ser of gear teeth associated with the first transmission unit and a 10 second set of gear teeth associated with second transmission unit.

Many vehicles fitted with one of the known speed control units are in addition protected by a separate disabling unit adapted to inhibit unauthorised driving of the vehicle. A feature of this

15 invention is that a combined speed control and disabling device can be provided, thus avoiding the need for separate units.

Thus according to another feature of the invention we propose a vehicle having a power unit and a driver-operated regulator for the power unit connected by a transmission characterised in that 20 a speed control device according to claim 5 is fitted in the transmission, with cruise control, and with a disabling ability whereby to disconnect the power unit from the regulator.

The invention will be further described by way of example with

reference to the accompanying drawings, in whic :-

Fig.l is a schematic diagram of a typical vehicle speed control system;

Fig.2 is a partial pespective view of a known vehicle speed limiting device;

Fig.3 is schematic view of one embodiment of speed limiting device in accordance with the invention;

Fig.4 is a view of the device of Fig.3, in its speed limiting mode;

Fig.5 is a schematic view of a second embodiment of speed limiting device according to the invention in its speed limiting mode;

Fig.6 is a view of the Fig.5 device in its disabled condition;

Fig.7 is a schematic view of a third embodiment of vehicle speed control device according to the invention; and

Fig.8 is a view of the device of Fig.7 in its speed control mode.

The vehicle speed limiting system of Fig.l includes a vehicle speed limiting device 10 fitted in linkage 12,13 between carburetter 14 of petrol engine 16, and foot-operated accelerator pedal 18. In an alternative embodiment the linkage 12,13 will be non-linear, comprising flexible cables directed around the

SUBSTITUTESHEET

- 4 - vehicle engine compartment (not shown) clear of other engine components. In a further alternative embodiment, pedal 18 will be replaced by a hand-operated lever.

Accelerator pedal 18 is mounted on pivot 20, so that as seen in 5 the layout of Fig.l, foot pressure in the direction of arrow A causes the pedal to pivot anti-clockwise. Device 10 is mounted on pivot 22, and in its normal operating mode will transmit the (left to right) pull from linkage 12 to linkage 13, whereby to open the throttle 24 of carburetter 14 to permit more fuel to

10 flow to engine 16. Abutments 28,30 limit the permitted pivoting movement of device 10, in known manner. Spring means are provided to return the arrangement to the rest position of Fig.l when the pedal pressure is released, usually comprising a carburettor throttle return spring and an accelerator pedal

15 return spring.

On a level road, in normal use more fuel to engine 16 will cause an increase in the rotational speed of drive shaft 26, which is connected to some or all of the vehicle wheels; this rotational speed can be measured in a number of ways known in the 20 art, and such speed measurement is coded and transmitted by way of line 32 to actuator 34, which itself is connected to control device 10. In an alternative embodiment the actual speed of one wheel is measured and fed to actuator 34.

One known arrangement of vehicle speed limiting device 10 is

shown schematically in Fig.2. It includes a pair of parallel plates or transmission units 44, 46 mounted on a common spindle 48, so that spindle 48 provides the aforementioned pivot 22. Plate 44 is a so-called input plate (connected by linkage 12 to pedal 18), and the other plate 46 is a so-called output plate (connected by linkage 13 to carburetter 14). Input plate 44 has a transverse flange 44a which acts as an abutment for a co-operating flange 46a on output plate 46; flange 46a is normally held in abutment with flange 44a by a torsion spring 47 forming a permenent coupling means for the plates 44,46. As above described, depression of accelerator pedal 18 causes input plate 44 to pivot about spindle 48, whereby in normal use output plate 46 follows (under the action of the torsion spring 47) to move linkage 13 to change the setting of the carburetter or fuel pump.

The actuator 34 is connected to the plates 44,46 by coaxial cables 50,52, the outer cable 50 being connected to input plate 44, and the inner cable 52 being connected to output plate 46. If the actual wheel speed exceeds the pre-set maximum for which the actuator is calibrated, actuator 34 operates to cause relative movement between cables 50,52 such that flange 46a is caused to separate from flange 44a extending torsion spring 47; as a result, in one typical operation, the spatial position of linkage 13 and thus the setting of throttle 24 remains unaffected notwithstanding movement to the right of linkage 12 (from additional depression of pedal 18). The known device thus

provides a lost-motion facility. If the facility is no longer required, for instance if the brakes are applied so that the vehicle loses speed, then the torsion spring acts to return flange 46a into abutment with flange 44a, but must also simultaneously drive cable 52 back within outer cable 50, agains the resistance of the gearing within actuater 34, and so is of significant strength.

Figs. 3-8 show embodiments of the invention, described i relation to a replacement for the "lost-motion" control arrangement of Figs 1 and 2 provided by co-axial cable 50,52.

"Forward" and "rearward" as used herein are respectively to th right and left as seen in these figures.

In the embodiment of Fig.3, plates 144, 146 of speed limitin device 100 have an outline shape generally similar to that o plates 44, 46. Plates 144,146 are mounted in cradle 101 by mean of a respective forward extension 102 on input plate 144, and rearward extension 104 on output plate 146. Extensions 102,10 each have a circular outer periphery, such that the plates ar mounted in the cradle to pivot between limits set by abutment corresponding to the abutments 28,30 of Fig.l. Extension 102 i annular and rigidly locates electric motor 106. In thi embodiment, input plate 144 is coupled to output plate 146 b torsion spring 145, to assist output plate 146 to follow inpu plate 144 to the rest position against abutment 28 when foo pressure is released from accelerator pedal 18.

SUBSTITUTESHEET

Torsion spring 145 helps to ensure that the input and output plates come into alignment when the gear teeth dis-engage, irrespective of the input plate position.

Input plate 144 has an annular rearward extension 108 terminating in face gear teeth 110. Output plate 146 has an annular forward extension 111 with axial castellations 112.

Face to face with gear teeth 110 are gear teeth 114 (Fig.4), provided as a forwardly extending annular array on a flexible coupling disc 118. The coupling disc 118 is rotatably mounted on spindle 116 of motor 106, and has radially-extending castellations 119 engaged with castellations 112, so that coupling disc 118 and output plate 146 pivot together about motor spindle 116. In an alternative embodiment, annular forward extension 111 of output plate 146 is slotted to receive radially directed fingers on flexible coupling disc 118; and in another embodiment output plate 146 has two forwardly extending bifurcated fingers adapted to mate with corresponding radial fingers of coupling disc 118.

Rigidly fixed to motor spindle 116 is drive disc 120 having a pair of forwardly extending fingers 122. Fingers 122 are located at diametrically opposed positions on the- drive disc 120. In an alternative embodiment, drive disc 120 has more than two fingers

122 e.g. three fingers 122 equally angularly spaced at a common

radius about drive disc 120.

Fingers 122 engage coupling disc, and cause it to flex so that those of its teeth 114 aligned with (i.e."below") fingers 122 engage corresponding gear teeth 110.

5 Fig.3 shows the position of the components when the vehicle is not in use, so that motor 106 is not energised; motor spindle 116 is at its extended position (fully housed within output plate 146 and thus fully rearward) , fingers 122 of drive disc 120 are spaced from coupling disc 118, and none of the gear teeth 114,

10 no are interengaged. In this position plates 114, 116 are effectively disconnected, even though pivoting movement of input plate 144 consequent upon depression of pedal 18 may result in some corresponding movement of output plate 126 through torsion spring 145 e.g. if torsion spring 145 is able to overcome the

15 carburetter return spring. However, the vehicle power unit is "disabled" since the transmission plates 144,146 are not coupled for normal movement together.

In one alternative embodiment, with torsion spring 145 fitted, a retractable peg in the output plate 146 is used to achieve 20 disablement of the throttle, preventing movement of the output plate prior to the plates being coupled by gears 110,114.

In an alternative embodiment in which torsion spring 145 is omitted, the gear teeth 110,114 are allowed to mesh only when

SUBSTITUTESHEET

both the input plate 144 and output plate 146 are at the datum position against abutment or stop 28 (sensed as by micro-switches), whereby means such as a retractable peg are not needed to restrain the output plate to ensure throttle disablement. If rapid fuel shut-off is required, as in an emergency braking condition, the gear teeth 110,114 are disengaged (as more fully described below and following rearward movement of motor spindle 116), and input plate 144 is returned to stop 28 by the carburetter return spring or the diesel pump spring; thereafter the gears are caused to re-engage, and full foot-pedal accelerator control is re-instated. If however there is required a gradual speed change, then this can be achieved by rotation of the motor spindle 116 in the appropriate direction.

An advantage of permitting engagement of the gear teeth 110,114 only in the fully retracted pedal position is that inadvertent inter-engagement of the teeth at some intermediate position, with possible distorted throttle control, is avoided.

If the linkage 12,13 to the carburetter throttle is disabled by disconnection of gears 110,114, it will remain so until motor 106 is energised to cause forward movement of motor spindle 116 to the position shown in Fig.4.

If desired, movement of motor spindle 116 to the Fig.4 position can be effected only upon operation of a disabler switch separate from the vehicle ignition switch, so that both switches need to

SUBSTITUTESHEET

- 10 -

be operated before the engine can respond to accelerator pedal movement, and be driven away in conventional fashion. Once however, as more fully described below, .. - ^* e of the teeth 114, 110 have been brought into engagement input plate 144 is 5 operatively connected to output plate 146 by way of these gears and castellations 112,119.

In the Fig.4 position, in which the plates 144,146 are coupled for direct transmission, fingers 122 of drive disc 120 engage and deform coupling disc 118, so that the gear teeth immediately

10 below the two fingers 122 i.e. as viewed in Fig.3 to the right of respective fingers 122, engage with the facing and aligned gears of gear teeth array 110. It will be understood that since coupling disc 118 is flexible, it becomes bowed so that the gear teeth not immediately below fingers 122 do not engage gear teeth

15 110. Gear teeth 110 are in an annular array and each is of substantially the same shape as gear teeth 114, also in annular array, but differ slightly in number.

If the speed limiting device 100 is now brought into operation, this is arranged to effect rotation of motor spindle 116. Upon

20 such rotation, drive disc 120 rotates with motor spindle 116. The differing number of gear teeth 114,110 respectively on the coupling disc 118 and on the input plate rearward extension 108 cause slow relative rotation of the coupling plate 118 and thus (by way of the castellations) slow rotative movement of the

25 output plate 146 relative to the input plate 144. This slow

relative rotation is arranged to be in the direction to cause the abutment on the output plate to separate from the abutment on the input plate (these abutments correspond to abutments 44a, 46a of Fig.2, but are not shown for clarity) to provide a lost-motion 5 between the foot pedal 18 and carburetter 14.

If the vehicle is now braked, so that the speed limiting device is not needed, then the actuater 134 will cause the motor spindle 116 to return to its initial position i.e. leftwards to the Fig.3 position, initially permitting disengagement of teeth 114,

10 110, and so allowing torsion spring 145 to effect relative rotation of the input plate 144 and output plate 146 until the abutments re-engage. Then motor spindle lib is re-engaged and moved rightwards to the Fig.4 position, to again bring teeth 114,110 to engagement, whereby to provide a coupling connection, 5 without lost-motion between pedal 18 and carburetter 14.

The embodiment of Figs. 5 and 6 is of an alternative construction. Input and output plates 244,246 are rotatably mounted on non-rotatable spindle 216; in an alternative embodiment, spindle 216 is coupled to one of the plates to rotate 0 therewith.

Motor 206 is mounted in a cradle 201 but on a different axis to that of input plates 244 and 246, and can rotate drive disc 220 by means of belt 250. In this embodiment the motor does not have a shaft reciprocating facility. Drive disc 220 is mounted upon

- 1 2 - an intermediate section of coupling disc 218 for rotation relative thereto, and has a pair of rearwardly extending diametrically-opposed fingers 222.

Coupling disc 218 is integral with input plate 244 , and has 5 gears 214 adapted to engage with forwardly facing gear teeth 210 integral with output plate 246. Coupling disc 218 can be deformed by fingers 222 of drive disc 220 upon movement in the direction of arrow B of operating member 252, whereby to effect engagement between aligned teeth of face gears 210, 214 to cause slow

10 relative rotation between input plate 244 and output plate 246. Input plate 244 is coupled to output plate 246 by a tension spring 245, effective to return the plates 244,246 to the rest position after release of gears 210,214 i.e. after rightward movement of operating member 252 to the Fig.6 position. In this

15 embodiment disengagement of gear teeth 212,214 is assisted by return spring 254.

The embodiment of Figs.7 and 8 disclose radially directed teeth on the inside and outside of axially extending cylinders 310,318 integral respectively with output plate 346 and input plate 344.

20 Inner cylinder 318 is the coupling member, being deformable radially outwards by a pair of opposed wedges 322 carried by a drive member 320 secured to spindle 316 of motor 306. The wedges are diametrically spaced, so that they act to bring the gears on 310,318 into engagement and thereafter upon rotation of motor

25 spindle 316 effect pivoting of output plate 346 relative to input

SUBSTITUTE SHEET,

plate 344 .

The coupling disc is made of a material able to flex, and of a resilience to return to the rest position of Fig.3, Fig.6, or Fig.7. However, a spring 254 (Fig.6) can be used to assist the rapid return of the coupling disc to its rest condition.

Because the input and output plates return to their normal (rest) position, following speed limiting, whilst the speed limiting gearing is de-clutched, the spring 145,245,345 need only be of relatively low strength. The proposed arrangement is compact, and can be dual purpose if the initial coupling engagement between the facing gears effected by motor spindle 116, 316 or operating member 252 only occurs upon positive operation of a "disabling" switch.

Although the device has been described in relation to a vehicle speed limiting arrangement, it will be understood that reverse movement of the motor rotation direction could be used to cause pivoting of the input plate in a direction corresponding to increased pedal depression, so permitting the vehicle speed to be increased up to cruising speed i.e. if the vehicle starts to climb an incline whereupon the wheel speeds would otherwise decrease, requiring extra fuel to maintain the vehicle speed. In the cruise control mode, with or without torsion spring, restraint of the input plate (as by a retractable peg, conveniently solenoid operated) may be required to ensure that

- 14 - only the output plate moves.

For cruise control, two separate devices can be used, one to effect speed limiting by providing a lost motion for linkage 13; and a second device to provide movement of linkage 12 in the 5 pedal depression direction. Each device can be alternately operated by a single actuator 34,134,234,334 responsive to speed measurements above ^* or below the specified range. Alternatively, the plates 144,146etc can at rest be spaced from each abutment 28,30, permitting one plate to be moved away from the other to 10 provide the respective increased fuel flow or decreased fuel flow relative to the pedal positon, as above described. In the usual arrangement wherein the cruise control facility is permitted to operate only with top gear engaged, the rotational speed of the engine (RPM) can be used to control actuator impulses.

15 It will be understood therefore that the disclosed prior art vehicle speed control device relies for its operation upon the use of a strong torsion spring permanently connecting the input and output plates, and itself acting as the coupling means. The coupling means of the present invention is the facing gearing,

20 when intermeshing at the selected positions "below" the fingers 122, and although a weak torsion spring can optionally interconnect the input and output plates, this is a return spring; alternatively or additionally the normal foot pedal return spring could return the input plate to its stop, and the normal carburetter (or fuel pump) return spring could return the

output plate to its stop; the torsion spring would assist the one plate to follow the other, when the gearing is disengaged.

It will also be understood that the coupling means provided by the torsion spring of the prior art device discussed above permanently connects the input and output plates; the torsion spring of this disclosure, when fitted to a vehicle speed control device with a disabling facility, will only intermittently be able to transmit torque between the plates.

It will be yet further understood that the annular teeth of this disclosure perform two functions (a) as a dog clutch, able to connect the input and output plates and making them act "as one"; and {b} a gear-box function able to impart differential movement between the plates to permit the "lost-motion", as required to "make flexible" the normal "rigid" transmission between the foot-pedal and carburettor (or fuel pump) .

SUBSTITUTESHEET