GB2081411A

GB2081411A - Flexible control cable

Info

Publication number: GB2081411A
Application number: GB8024509A
Authority: GB
Original assignee: Ford Motor Co Ltd; Ford Motor Co
Current assignee: Ford Motor Co Ltd; Ford Motor Co
Priority date: 1980-07-25
Filing date: 1980-07-25
Publication date: 1982-02-17

Abstract

A flexible control cable for connecting an operating element such as an accelerator pedal 2 to a controlled element such as a carburettor throttle control 3 comprises a flexible sheath (6), a coaxial core (7) slidable therein, and mountings 12, 15 for securing the ends of the sheath to supports 10, 13. One of the mountings (15) comprises a first part (16) secured to the sheath (6) and a second part (26) which is secured to a support 13. The two parts (16, 26) can move axially relative to each other when sufficient axial load is applied to the sheath (6). A detent comprising flexible fingers (32) on one part (26) carrying radial teeth 33 which engage in circumferential grooves (21) on the other part (16), retains the two parts in one of a plurality of discrete axially spaced positions but accommodates relative movement of the two parts. During installation, the cable automatically adjusts to the length required so that the range of movement of the operating element coincides with that of the controlled element. <IMAGE>

Description

SPECIFICATION Flexible control cable This invention relates to flexible control cables.

Flexible control cables, such as those used in motor vehicles to interconnect an accelerator pedal with a carburettor throttle control lever, comprises a flexible sheath, mountings for securing the ends of the sheath to respective supports, and a coaxial core slidablewithin the sheath, the ends of which, in use, are respectively connected to an operating member e.g. the accelerator pedal, and a controlled member e.g. the carburettor throttle control lever.

In order to ensure that the range of movement of the controlled member coincides with that of the operating member, it is usually necessary to adjust the effective length of the cable during assembly. For example, it is desirable to adjust the carburettor throttle control cable so that the throttle control lever reaches its fully open position only when the accelerator pedal is fully depressed. This is usually achieved by manually adjusting the position of one end of the sheath relative to one of the mountings.

For example British Patent Specification No. 1226516 discloses a flexible control cable in which one of the mountings comprises a first member fixed to a support and a second member fixed to the sheath and threadedly mounted in the first member so that the effective length of the cable can be adjusted by rotating the second member relative to the first after installation. Although this arrangement is effective, it nevertheless involves the assembly maker in a relatively time-consuming operation.

British Patent Specification No. 1358012 discloses an automatically adjustable flexible control cable in which the core is attached to the operating member by means of a bulbous member fixed to the core acting on one end of a sleeve of resiliently deformable plastics material, the other end of which abuts the operating member. When the controlled member reaches the limit of its movement, further movement of the operating member forces the sleeve over the bulbous member until the operating member reaches the limit of its movement. The frictional force exerted on the bulbous member by the sleeve thereafter retains the bulbous member in position.Although this arrangement allows automatic adjustment of the effective length of the control cable, the frictional forces exerted by the sleeve are difficult to predict and will vary from sample to sample due to manufacturing tolerances. Moreover if the control cable is removed during maintainance or repair of the vehicle, readjustment of the cable is difficult.

According to the present invention there is provided a flexible control cable comprising a sheath, a coaxial core slidable within the sheath, mountings for securing the ends of the sheath to respective supports, one of the mountings comprising a first part secured to the sheath and a second part adapted to be secured to a support, the two parts being movable relative to each other to adjust the effective length of the cable characterised in that the two parts are movable relative to each other under an axial load and in that the two parts are retained in a plurality of discrete axially spaced positions by a detent.

The use of a two-part mounting capable of being retained in any one of a plurality of discrete axially displaced positions by a detent allows automatic adjustment of the effective length of the cable. Thus, in use, the ends of the core are attached to a controlled member and an operating member. Initial movement of the operating member moves the core in the sheath so that the controlled member moves to the end of its range of travel. Further movement of the operating member applies an axial load to the sheath which causes relative axial movement of the two parts of the mounting until the operating member reaches the limit of its travel.

Since the adjustment involves the action of a detent, the control cable can easily be readjusted after it has been removed and replaced, and the detent itself can be constructed so as to allow close control over the forces required to effect relative movement of the two parts of the mounting.

In the preferred embodiment of the invention, the detent comprises one or more radial teeth on one of the parts which can engage in a plurality of axially spaced radial notches on the other part. By appropriately shaping the profile of the notches and teeth the forces required to produce relative axial movement of the two parts of the mounting can be controlled.

The detent can therefore be constructed to yield more easily under forces tending to cause relative movement of the two parts in one axial direction than forces tending to cause the two parts to move in the other axial direction so that, for example, the two parts can easily be separated from each other for readjustment of the cable.

The notches are conveniently in the form of circumferential grooves on one of the two parts so that the two parts can operate in any relative angular orientation, and the teeth are preferably formed on respective axial fingers positioned circumferentially around the cable.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a sketch showing a control cable in accordance with the invention installed in a vehicle; Figure 2 is an elevation of a mounting forming part of the cable of Figure 1; Figure 3 is an axial cross-section through one part of the mounting of Figure 2; and Figure 4 is an axial cross-section through the other part of the mounting of Figure 2.

Referring to the drawings, a flexible control cable 1 interconnects an accelerator pedal 2 with the throttle control lever 3 of a carburettor 4. The pedal 2 is pivotable between an idle position, illustrated in chain-dotted lines in Figure 1, and a fully depressed position, illustrated in full lines, in which the pedal rests against a floor stop 5. The throttle control lever 3 is pivotable through about 90 between a closed position and a wide-open position, illustrated in Figure 1, and the control cable 1 must be adjusted so that as the pedal 2 reaches its fully depressed position, the throttle control lever 3 reaches its wide open position.

The control cable 1 comprises a flexible sheath 6, of a conventional wound-wire construction, and a coaxial core cable 7 which can slide within the sheath 6. One end of the cable 7 is fastened to the throttle control lever 3 of the carburettor by a connecting block 8 and the other end is connected to the pedal 2 by means of a link 9. The end of the sheath 6 adjacent the pedal 2 is secured to a body panel 10 of the vehicle by a first mounting 12, which is a snap-fit into an aperture in the panel 10. The other end of the sheath 6 is secured to a bracket 13 on the carburettor 4 by means of a 2-part mounting 15, illustrated in detail in Figures 2to 4.

The first part 16 of the mounting 15 comprises an integral moulding of plastics material having a connector 17 which has an axial recess 18 to which the end of the sheath 6 is moulded.

A shank 19 extends axially from the connector and includes a central passage 20 through which the core cable 7 extends. The external surface of the shank 19 is provided with a series of axially spaced notches in the form of circumferential grooves 21.

The second part 26 of the mounting 15 also comprises an integral moulding of plastics material having a central passage 27 through which the core cable 7 passes. The second part 26 is provided with an external flange 28 near its central region and a square shank 29, the shoulders of the shank 29 being chamfered as indicated at 29'. The bracket 13 has a square aperture for receiving the shank 29, and the shank 29 is secured therein by inserting the shank 29 into the aperture to bring the flange 28 into abutmenu with the bracket 13, and then rotating the shank 29 in the aperture so that the edges of the aperture bite into the chamfered section 29'.

The end of shank 29 is cylindrical and of smaller external diameter than the shank and provides a seat for a compression spring 30 (Figure 1) which acts between the mounting 15 and the connecting block 8 attached to the end of the core cable 7 to bias the block 8 away from the mounting 15.

The other end of the second part 26 is provided with a plurality of axially extending fingers 32 arranged circumferentially around the cable 7. The end of each finger 32 carries a radially-inwardly directed tooth 33 each of which has a profile complementary in shape to the grooves 21 in the shank 19 ofthefirst part 16 ofthe mounting 15. The fingers 32 are radially flexible so that the shank 19 can be inserted into the central passage 27 of the second part by the application of axial force, thereby engaging the teeth 33 in one of the grooves 21. The teeth 33 and grooves 21 thus act as a detent for retaining the two parts 16, 26 of the mounting 15 in any one of a plurality of discrete axially spaced positions.The profiles of the teeth 33 and grooves 21 are chosen so that the teeth 33 yield more easily under forces tending to cause axial movement of the two parts 16, 26 away from each other than towards each other.

Consequently, when the control cable assembly 1 is installed in a vehicle, the two parts of the mounting 15 are arranged in an initial position (illustrated in Figure 2) in which the teeth 33 engage in the groove 21 nearest the end of the shank 19 of the first part.

With the two parts of the mounting in this position, the control cable is secured to the pedal 2, the body panel 10, the bracket 13 and the throttle control lever 3, as illustrated in Figure 1, with the pedal 2 in its idle position. In order to adjust the length of the cable to match the movement of the pedal 2 to that of the throttle control lever 3, the worker depresses the pedal 2 towards the floor stop 5. During this movement the control lever 3 will be pulled towards its wide-open position but will generally reach its wide open position before the pedal 2 is fully depressed.

Further movement of the pedal 2 towards the flood stop 5 increases the tension in the cable 7 which places an axial load on the sheath 6 tending to move the first part 16 of the mounting 15 towards the second part 20. When the load on the sheath 16 is sufficient to deflect the fingers 32, the shank of the first part 16 moves further into the central passage 27 of the second part 16, effectively shortening the length of the sheath 6. This in turn permits further movement of the pedal 2towards the floor stop 5.

This adjustment continues automatically until the pedal 2 is engaged with the floor stop 5, as shown in Figure 1. At that time the range of movement of the pedal 2 will coincide with the range of movement of the throttle control lever 3.

If for any reason it becomes necessary to disconneck the control cable 1 from the pedal 2 and carburettor 4, the first part 16 of the mounting can easily be withdrawn from the second part 26 allowing the cable to be refitted and readjusted by the process described above.

Claims

1. A flexible control cable comprising a sheath, a coaxial core slidable within the sheath, mountings for securing the ends of the sheath to respective supports, one of the mountings comprising a first part secured to the sheath and a second part adapted to be secured to a support, the two parts being movable relative to each other to adjust the effective length of the cable characterised in that the two party are movable relative to each other under an axial load and in that the two parts are retained in a plurality of discrete axially spaced positions by a detent.

2. A control cable according to Claim 1 wherein the detent comprises one or more radial teeth on one of the parts and a plurality of axially spaced radial notches on the other part.

3. A control cable according to Claim 2 wherein the notches comprise circumferential grooves on the said other part.

4. A control cable according to Claim 2 or Claim 3 wherein each tooth is formed on respective axial finger circumferentially positioned around the cable.

5. A control cable according to any one of Claims 1 to 4 wherein the detent yields more easily under forces tending to cause axial movement of the two parts in one axial direction than under forces tending to cause axial movement of the two parts in the other axial direction.

6. A control cable according to any one of Claims 1 to 5 wherein the first and second parts of the mounting are each formed as integral mouldings.

7. A control cable substantially as hereinbefore described, with reference to the drawings.