GB2310020A - A control cable assembly including an over-travel device having a vibration isolator - Google Patents

Abstract

A resilient vibration isolator 21, eg of elastomeric material, is supported on an outer surface of an inner flange member 22 and interposed between an abutment face 26 and an inner flange face 25, to which it is bonded. The isolator 21 attenuates vibrations transmitted to outer sleeve 19B from support bracket 13. If accelerator pedal 17 is over depressed outer cage 24 of over-travel device 20 will move in the direction of arrow 27 with respect to inner flange member 22, which remains fixed by compression of outer sleeve 19B against adjusting screw 14 causing spring 23 to be compressed. The compression of spring 23 allows the over depression of the pedal 17 to be accommodated without stretching or snapping of cable 10 which is slidably supported in outer sleeves 19A, 19B, either one of which may be flexible or rigid. The assembly operates a lever 11 of a fuel pump 150 forming part of a motor vehicle diesel engine 15.

Description

A Flexible Control Cable This invention relates to flexible control cables and in particular to flexible control cables for transmitting motion.

It is known to provide a flexible control cable of the "Bowden" type in a motor vehicle to control the operation of a remote system. One example of such an application is the control of the fuelling lever of a fuel pump forming part of a diesel engine. The cable connects the accelerator pedal to the operating spindle of the fuel pump.

These cables are used because they offer a cost effective way of connecting the input mechanism to the device to be actuated in circumstances where a rigid connection is not practical, such as where the connection route includes a curved path.

A problem with these cables is the transmission of vibrations along them.

It is an object of this invention to address this problem.

According to the invention there is provided a control cable assembly comprising a flexible cable for connecting an input means to a device to be actuated, a two part outer sleeve having a first part and a second part slidably supporting said flexible cable and including an over-travel device connecting the first and second parts of the outer sleeve to allow a limited longitudinal displacement therebetween, the over-travel device having a first member for attachment to the first outer sleeve, a second member for attachment to the second outer sleeve and a spring means to bias the first and second members apart wherein the overtravel device includes a resilient vibration isolation means interposed between said first member and said second member to attenuate the transmission of vibrations from one outer sleeve to the other outer sleeve.

Said first sleeve may be flexible and said second sleeve may be a rigid member.

Said second sleeve may be flexible and said first sleeve may be a rigid member.

Said over-travel device may be attached to one end of said flexible sleeve by one of said members and to a support means by the rigid member.

Said vibration isolation means may be fixed to said first member.

Said vibration isolation means may be fixed to said second member.

Said vibration isolation means may be made of an elastomeric material.

The invention also provides a fuelling system for a motor vehicle diesel engine including a control cable assembly wherein the input means comprises an accelerator pedal and the device to be actuated comprises a diesel fuel injection pump.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows part of a control system for a diesel engine including a control cable assembly in accordance with the invention; and Figure 2 shows the over-travel device of the control cable assembly of Figure 1 in detail.

With reference to Figure 1 a control cable assembly 100 is shown forming part of the control system for a motor vehicle diesel engine 15. The control cable assembly 100 is a "Bowden" type cable and comprises a flexible inner cable 10, a two part outer sleeve having first and second sleeve parts l9A, 19B, an over-travel device 20 interposed between the first and second sleeves 19A, l9B and an adjustment screw 14.

At one end, the inner cable 10 passes through a bulkhead 18 and is kept in communication with an input means in the form of an accelerator pedal 17 by a solder nipple 12B. At its other end, the inner cable 10 is kept in communication with a lever 11 by a solder nipple 12A.

The lever 11 forms part of a fuel pump 150 of the diesel engine 15 and can pivot between an idle screw 151 and a stop screw 152 of the fuel pump 150.

The adjustment screw 14 is threaded through a support bracket 13 attached to the diesel engine 15 and is used to connect the second sleeve 19B to the bracket 13.

With particular reference to Figure 2, the over-travel device 20 of the control cable assembly 100 is shown in detail. The over-travel device 20 includes an outer cage 24 and an inner flange member 22 which are able to move linearly in relation to each other within the limit of the length of the outer cage 24. The outer cage 24 includes an abutment face 26 in opposition to a flange face 25 of the inner flange member 22. The flange face 25 is biased towards the abutment face 26 by a spring 23 acting between a back face 28 of the outer cage 24 and a rear face 29 of the inner flange member 22.

A resilient vibration isolation means in the form of a vibration isolator 21 made of elastomeric material is interposed between the flange face 25 and the abutment face 26. The vibration isolator 21 is substantially the same size as the flange face 25 and the abutment face 26.

The inner cable 10 is slidably supported in a flexible outer sleeving means comprising the first and second sleeves 19A, 19B. The first sleeve l9A is longer than the second sleeve 19B and follows a curved path. At one end, the first sleeve 19A is attached to the over-travel device 20 and at its other end it abuts the vehicle bulkhead 18 close to the accelerator pedal 17.

The second sleeve 19B is at one of its ends attached to the inner flange member 22 and at the other end is attached to the adjustment screw 14. The adjustment screw 14 is screwed through a mounting bracket 13 rigidly fixed to the diesel engine 15 to adjust slack and lost motion for the lever 11.

When the driver of the vehicle to which the diesel engine is fitted wants to accelerate, he depresses the accelerator pedal 17 which pivots about its fixing and pulls down the inner cable 10 in the direction of the arrow 16. This pulling action is transmitted to the opposite end where the inner cable 10 pulls the lever 11 away from its idle screw 151 until further movement of the lever is prevented by abutment of the lever with the stop screw 152.

A return spring (not shown) is provided to continuously bias the lever 11 back towards its idle screw 151.

Therefore, as the pressure is removed from the accelerator pedal 17, the lever 11 will move back towards the idle screw 151.

When the lever 11 has been pulled to its stop screw 152, the fuel pump 150 is supplying maximum fuel and the cable 10 cannot be pulled back any further. Conventional setting of the accelerator pedal 17 will still leave about 100 of pivotal movement before it hits its pedal stop (not shown). If the accelerator pedal 17 is then further depressed, the cable assembly will enter an "over-travel" condition and the over-travel device 20 will operate.

During an over-travel condition, further depression of the accelerator pedal 17 will cause the outer cage 24 to move in the direction of the arrow 27 with respect to the inner flange member 22, which remains fixed by the compression of the second sleeve 19B against the adjusting screw 14 causing the spring 23 to be compressed. The compression of the spring 23 allows the over-travel of accelerator pedal 17 to be accommodated without stretching or snapping the cable 10. When the accelerator pedal 17 is released sufficiently to leave the over-travel state, the spring 23 releases its compressive force and biases the flange face 25 and the abutment face 26 back towards their normal state , in which they are in abutment.

The vibration isolator 21 is supported on the outer surface of the inner flange member 22 and bonded to the inner flange face 25 thereof. At rest, the vibration isolator 21 is biased into compression against the abutment face 26 by the compression of the spring 23 acting between the back face 28 of the outer cage 24 and the rear face 29 of the inner flange member 22.

Vibrations from the diesel engine 15 are transmitted into the adjustment screw 14 and then into the second sleeve 19B. The presence of the vibration isolator 21 prevents or reduces the vibrations from being transferred via the cage 24 to the first sleeve. The perceived vibrations at the accelerator pedal 17 end are thereby considerably reduced compared to a flexible control cable in which no vibration isolator is used.

If the vibration isolator 21 collapses through fatigue or contamination, the spring 23 will still bias the inner flange 25 and the abutment face 26 towards each other and control over the system will not be lost.

Although the use of first and second flexible sleeves 19A, 19B allows the over-travel device 20 to be positioned anywhere along the length of the outer sleeving, it will be appreciated that it is possible to use only one flexible outer sleeve and to mount the over-travel device 20 at one end of that sleeve. By way of example, the inner flange member 22 and the adjustment screw 14 could by formed as one, thereby mounting the over-travel device directly to the support bracket 13 and eliminating a second flexible sleeve.

Claims (10)

1. A control cable assembly comprising a flexible cable for connecting an input means to a device to be actuated, a two part outer sleeve having a first part and a second part slidably supporting said flexible cable and including an over-travel device connecting the first and second parts of the outer sleeve to allow a limited longitudinal displacement there between, the over-travel device having a first member for attachment to the first outer sleeve, a second member for attachment to the second outer sleeve and a spring means to bias the first and second members apart wherein the over-travel device includes a resilient vibration isolation means interposed between said first member and said second member to attenuate the transmission of vibrations from one outer sleeve to the other outer sleeve.

2. A control cable assembly according to claim 1 wherein said first sleeve is flexible and said second sleeve is a rigid member.

3. A control cable assembly according to claim 1 wherein said second sleeve is flexible and said first sleeve is a rigid member.

4. A control cable assembly according to claim 2 or claim 3 wherein said over-travel device is attached to one end of said flexible sleeve by one of said members and to a support means by the rigid member.

5. A control cable assembly according to any one of claims 1 to 4 wherein said vibration isolation means is fixed to said first member.

6. A control cable assembly according to any one of claims 1 to 4 wherein said vibration isolation means is fixed to said second member.

7. A control cable assembly according to any preceding claim wherein said vibration isolation means is made of an elastomeric material.

8. A control cable assembly substantially as described herein with reference to the accompanying drawings.

9. A fuelling system for a motor vehicle diesel engine including a control cable assembly according to any preceding claim wherein said input means comprises an accelerator pedal and said device to be actuated comprises a diesel fuel injection pump.

10.A fuelling system for a diesel engine substantially as described herein with reference to the accompanying drawings.