GB2060809A - Bowden control system - Google Patents

Abstract

A mechanical remote control system for simultaneously operating two devices, for example two vehicle brake mechanisms (9, 14), comprises a Bowden mechanism (4) the inner component (3) of which is connected at one end to one of those mechanisms (9) and at its other end to a hand-lever or other actuator (1). The end of the conduit (5) of the Bowden mechanism (4) which is remote from the hand-lever is connected to an abutment (8). The conduit end nearer the hand- lever is connected by a coupling device (6) to a tie (12) for actuating the other mechanism (14). <IMAGE>

Description

SPECIFICATION Mechanical remote control systems This invention relates to mechanical remote control systems whereby movement can be simultaneously transmitted to two spaced independent devices via a common flexible transmission mechanism (for example a Bowden-type mechanism) comprising relatively axially displaceable inner and outer members.

Such systems are employed in certain vehicles for operating left and right-hand wheel brakes responsive to operation of a handbrake lever. In these known systems the inner member of a Bowden mechanism transmits a pull load to the operating lever of one of the brakes and the reaction force on the outer member, i.e., the conduit, of such mechanism exerts a thrust on a displaceable coupling device which is located between the two vehicle wheels and is connected to the operating lever of the other brake. An example of such a braking system is described in British Patent 1464967.

Such known control systems require a layout of the force transmitting components which it is not always convenient or desirable to adopt, for example, because of the available space envelope in which the system has to be installed or because that lay-out does result in sufficiently high force-transmission efficiencies.

It is an object of the present invention to provide a system which is more suitable for at least some environments of use.

According to the present invention there is provided a mechanical remote control system wherein there is a flexible remote control mechanism (hereafter called the "master mechanism") comprising an inner force-transmitting member longitudinally displaceable within a conduit; one end of said inner member is connected to an actuator and its other end is connected to a first part to be actuated; the conduit is connected at or near its end remote from the actuator to an abutment and is connected at or near its other end to a coupling device which is free to undergo movement towards the actuator responsive to reaction force imposed on the conduit when a pull force is applied to the inner member of said mechanism via said actuator; and said coupling device is connected via a tie to a second part to be actuated; whereby exertion of a said pull force by said actuator causes simultaneous actuation of said two parts.

It is an important advantage of the invention, in comparison with the known systems before referred to, that the coupling device does not have to be located between the first and second parts to be actuated. The coupling device can in fact be located at any desired distance from a notional line joining such actuatable parts. The system according to the invention is therefore more versatile in that the lay-out of the components is more adaptable to different installation requirements.

A further advantage of the invention is that the arrangement of the coupling device at or towards the force-input end of the master mechanism makes it possible in various circumstances of use to select component layouts which result in higher efficiencies of load transmission.

The tie connecting the coupling device to the second part to be actuated is preferably a flexible member, for example a cable. Most preferably, the tie constitutes the inner member of a second flexible remote control mechanism comprising a conduit in which such member is longitudinally displaceable. In these circumstances the tie can transmit loads along a non-rectilinear path without need for a sheave or other local fixed guide for imposing directional change on the tie.

It is very suitable and it is preferred for the master mechanism, and a said second flexible mechanism comprising the tie and a guiding conduit therefor, to be a Bowden mechanism in the normal usage of that term i.e. a mechanism wherein the inner member is a flexible wire or cable slidable in contact with the conduit or a conduit-liner. For convenience the master mechanism and the said second mechanism will hereafter be referred to as Bowden mechanisms. But it is to be understood that the master mechanism, and/or the said second mechanism if used, may be of a type comprising caged ball bearings by which the inner member is supported within the conduit. In such a mechanism the inner member can be in the form of a flexible strip. (See e.g.British Patent 1.000.550) The invention has been made primarily for vehicle braking installations wherein movement of the actuator, which may be a hand-or foot-operated element, serves to apply the brakes of two opposed wheels, which may be the front wheels or the rear wheels of the vehicle. The invention includes a vehicle in which there is a braking installation incorporating the invention.

The invention affords particularly important potential advantages as applied to braking systems for operating the brakes of vehicle wheels with independent suspension. When using the previously known system herein be fore described, for operating left and righthand wheel brakes. the arrangement of the displaceable coupling devie at the force-output end of the master mechanism has the consequence that it is necessary to employ both a second and a third Bowden mechanism for transmission of the applied force to the brakes of two wheels with independent suspension.

The system arrangement according to the present invention enables the braking force to be transmitted to twoindependently suspended wheels using only two Bowden mechanisms.

In this particularly important embodiment of the invention. the inner and outer members of the second Bowden mechanism, are directly connected to the independently suspended wheel support units.

By using only two Bowden mechanism where three were previously necessary, production costs can be reduced and installation of the braking system is simplified. Moreover given loads can be transmitted with greater efficiency.

In a braking system wherein the master mechanism and the second Bowden mechanism are connected directly to independently suspended units as above described, it suffices to provide a single abutment, extraneous to said units, for sustaining the reaction force on the system. This abutment is connected to the conduit of the second Bowden mechanism.

Preferably the braking system incorporates a single adjustment device by adjustment of which the effective length of both the master and the second Bowden mechanisms can be adjusted. This adjustment device may be operative at the point of connection between the conduit of the second Bowden mechanism and a said abutment for receiving the reaction force on such conduit. Or said adjustment device can be operative at the point of connection between the coupling device and the conduit of the master mechanism.

It is very advantageous for the coupling device to form a passageway through which the conduit of the master mechanism is threaded and subsequently secured in selection position therealong. This feature is beneficial in facilitating the setting up of the system in operative condition in a given vehicle or other use environment for actuating given devices. The employment of a coupling device of that form in mechanical remote control systems is the subject of our co-pending International Application No filed on the same day as the present application and entitled: Mechanical remote control assemblies.

It is particularly advantageous if the conduit of the master mechanism forms an external screw profile and an adjustment nut or nuts is or are screwed directly onto such conduit for abutment against the coupling device as is exemplified hereinafter.

The actuator, e.g. the hand-brake lever, of a system according to the invention can be directly connected to the inner member of the master mechanism. Alternatively and as hereinafter also exemplified, said actuator can be connected to said inner member via one or more coupling devices from which load applied to the actuator can be simultaneously transmitted to one or more further actuatable devices located at another or other load output point(s).

Certain embodiments of the invention, selected by way of example. will now be described with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a general view of a hand-brake system embodying the invention; Figure 2 is a general view of another such system; Figure 3 shows in more detail the coupling device used in the system shown in Fig. 2; Figure 4 shows on the left-hand side the female adjustment nut and on the right-hand side a coupling device insert component used in the system shown in Fig. 2; and Figure 5 is a general view of a four-wheel brake installation in which a braking system according to the present invention is employed for actuating the brakes of two of the four wheels.

In the system shown in Fig. 1, a handbrake lever 1 is pivoted at 2 and is connected to the inner member 3 of a Bowden-type mechanism 4 which is the master mechanism of the system. The end portion of the conduit 5 which is nearer the hand-brake lever 1 is secured in a socket in a coupling device 6.

The end of the conduit remote from the handbrake lever 1 carries a swaged end fitting 7 which is secured to an abutment 8 adjacent a left-hand wheel brake lever 9 to which the inner member 3 of the mechanism is connected. A helical return spring 10 is interposed between the end fitting 2 and the lever 9 so as to urge the mechanism 4 into its release position.

The coupling device 6 has spaced side lugs 11, 11' to which one end of the inner member 1 2 of a second Bowden-type mechanism 1 3 is attached. The other end of such inner member is connected to the lever 14 of the right-hand wheel brake. The ends of the conduit 1 5 of this second mechanism are secured to abutments 16 and 17. A compression spring 1 8 is interposed between the said brake lever and the abutment 1 7 so that this spring also assists return of the system to its release position.

When the hand-brake lever is moved to apply the brakes, the tensile load on the inner member 3 of the master mechanism imposes a compressive reaction load on the conduit 5 of that mechanism. This compressive reaction load is transmitted to the coupling device 6 and from that device to the right-hand wheel brake via the inner member 1 2 of the second Bowden mechanism 1 3. Consequently the two brakes are applied simultaneously under balanced forces.

The coupling device 6 does not need to be supported by any means other than those shown. But further support means can be employed provided that it permits the required movements of the coupling device. For exam ple the coupling device can be connected to a fixture by a pin and slot connection allowing bodily linear and slight pivotal motion of the coupling device.

The inner member 1 2 of the second Bowden mechanism 1 5 can be detachably connected to the lugs 11, 11' of the coupling device. The second Bowden mechanism may be installed in the vehicle or assembled to a vehicle brake unit before being connected to the coupling device and the first Bowden mechanism can likewise be installed in the vehicle or connected to a said brake unit where at any convenient time, independently of the second mechanism.

For adjusting the system, adjustment nuts 1 9 are provided on a threaded metal end fitting on the conduit 1 5 of the second Bowden mechanism. This type of adjustment facility on Bowden mechanisms is well known per se. By manipulation of the nuts the curvature and therefore the effective length of that second mechanism can be adjusted. And by virtue of the connection between the inner member of that mechanism and the coupling device 6, the adjustment is automatically accompanied by variation in the curvature and therefore the effective length of the first Bowden mechanism 4.

The form and orientation of the abutments 8 and 1 7 will depend on the vehicle design.

They will not necessarily be orientated as shown in the figure. The system as shown in Fig. 1 can be employed for example for actuating the brakes of right-hand and lefthand front or rear vehicle wheels mounted on a rigid axle. In that case the abutments 8 and 1 7 can be fixtures located on the axle, near to the respective wheels, and orientated so that the projecting ends of the inner members of the two Bowden mechanisms are parallel with that axle.

The system shown in Fig. 1 can also be employed, with the considerable advantages hereinbefore referred to. for actuating the brakes of independently suspended wheels. In this case, the abutments 8 and 1 7 will be fixtures on the wheel assemblies themselves.

For example those abutments may be constituted by the housings of the brake mechanisms which include the levers 9 and 1 4. or they may be fixtures (relative to such levers), located within such housing, depending on the type of the brakes concerned.

Whether applied to fixed axle or independently suspended wheels, the illustrated system is adaptable to various lay-outs providing different positions of the coupling device 6 relative to the axes of the wheels. It is merely necessary to select Bowden mechanisms of appropriate length. By locating the coupling device at an appreciable distance from the wheel axis as suggested in Fig. 1, the Bowden mechanisms can be laid along shallow curves. On the other hand when the coupling device is located nearer the said axis the lengths of the Bowden conduits can be shorter and that is a factor of significance for both cost and operating efficiency. If the coupling device is set closer to the wheel axis, this does not mean that the hand-brake lever 1 must also be closer to that axis.The projecting portion of the inner member 3 of the master mechanism, between the coupling device and the hand-brake lever, can be longer.

The system affords a remarkably high aggregate output force. The output force is in excess of the force applied to the input end of the first Bowden mechanism and approaches a value equal to twice that applied force minus only a loss factor which depends on the operating efficiencies of the individual mechanisms.

It is within the scope of the invention to employ a cable without a guiding conduit but running over sheaves, in place of the second Bowden mechanism 1 3 in Fig. 1. Such a cable can be connected to the coupling device by a screw clamp permitting the effective length of such cable to be adjusted. However the use of the Bowden mechanism is preferred.

Fig. 2 shows a remote control system according to the invention installed for opearating the brake mechanisms of opposed independently suspended wheels 20, 21. The brake mechanisms are enclosed in housings 22, 23 respectively to which the conduits of the two Bowden mechanisms employed in the system are secured. The system is similar to that shown in Fig. 1 except for the form of the coupling device and the adjustment facility. Parts corresponding with those shown in Fig. 1 are denoted by the same reference numerals.

The coupling device 24 in Fig. 2 is of the preferred form herein before described. It is formed to define a passageway through which the conduit of the master mchanism 4 is threaded. The conduit can be pushed through the coupling device to bring the latter to any required position along the conduit when the system is being set up for operation. The conduit 25 of the master mechanism comprises closely helically interwound wires which form at the exterior surface of the conduit a male screw and a female adjuster 26 is in direct screw engagement with such male screw so that such adjuster can be screwed along the conduit to any desired adjusted position along the conduit. The said conduit may for example have any of the forms described and shown in British Patent No 1 409 526.The adjuster 26 is in the form of a plastics nut with a tapered split spigot portion which is insertable into an end of the adjuster so that the nut becomes firmly clamped onto the conduit and the coupling device and nut thereafter move together as a unit during the operations of the mechanism.

The construction of the coupling device and adjuster are described in more detail hereafter with reference to Figs. 3 and 4.

The formation of the coupling device so that the conduit 25 of the master mechanism passes through it affords important advantages. Because the position of the coupling device relative to the length of the conduit can be varied to suit specific installation conditions, the length of the conduit of the master mechanism is not so critical as it is is when using a coupling device as shown in Fig. 1. The inner member 3 of the mechanism is fully supported by the conduit over the full length of the coupling device and the illustrated coupling device is formed so as to hold that portion of the conduit in a curved condition appropriate to the lie of the mechanism.

Moreover the inner member 3 is also supported by the conduit 25 over a distance beyond the coupling device because an end portion of the conduit projects from such device. This projecting end portion of the conduit is free to flex responsive to arcuate movements of the connecting point between the inner member 3 and the hand-brake lever 1. This feature is conducive to smooth and efficient operation of the system. The aggregate of the output forces in relation to a given input force are greater than in a system according to Fig. 1.

Referring to Figs. 3 and 4: the coupling device 24 is formed from a single metal blank. The shaping of the blank and the manner of folding it are such that the folded blank defines a passageway 27 for the conduit of the master mechanism and opposed marginal portions of the blanle including two lobes 28, 29 are brought into parallel relationship. Holes are formed in the lobes and they together form a two-ply lug to which the inner member 1 2 of the second Bowden mechanism is attached.

Fig. 4 shows the female adjustment nut 26 for screwing onto the conduit of the master mechanism. The nut has a tapered and axially slotted spigot portion 30 for clamping onto the conduit. A tubular insert component 31 is provided which has a spigot portion 32 for insertion into an end of the passageway 27 in the coupling device and which at its other end has a conical socket 33 whose angle of taper is similar to that of the tapered spigot 30 of the female adjustment member.

The spigot portion 7 of the insert component has an integral key portion 34. When the insert component is inserted into the coupling device this key portion is received by a slot 35 between opposed portions of the folded blank so that the insert component is prevented from rotating in the coupling device.

The position at which the adjuster 26 is set along the conduit of the master mechanism determines the effective length of this conduit. The adjuster can be located at any desired position along the conduit when setting up the system and adjustments can be easily effected at any time. After adjustment the spigot portion is pushed firmly into the insert component 31 in the end of the coupling device so that this spigot portion becomes firmly clamped onto the conduit. The spigot portion is self-locking in the conical socket 33 of the insert component because of the angle of taper and the coefficient of friction between the contacting surfaces. Consequently, when a braking force is released then coupling device and adjuster move as a unit away from the hand-brake lever.If the tapered spigot portion of the adjustment nut is not pushed sufficiently firmly into the receptive socltet in the insert component when setting up the system or following an adjustment, such clamping occurs automatically responsive to the first or next following application of the braking load on the system.

It is not necessary in the system shown in Figs. 2 to 4, to provide an adjustment facility on the conduit of the second Bowden mechanism 13, but such a second adjustment facility can be provided if required. This further facility can be as shown in Fig. 1 or the conduit of the second mechanism can be formed with an external screw profile and have a female adjustment member directly screwed thereon as in the case of the first mechanism. Such a conduit with an adjustment nut directly screwed thereon could of course be used in place of the conduit 1 5 in Fig. 1, the tapered adjustment nut being arranged to co-operate with an aperture in a fixture such as 16.

It is not an essential feature of the present invention for the inner member of the master mechanism to be directly connected to the actuator. For example the inner member of the master mechanism can be indirectly connected to the actuator, e.g. via a rod, via another cable, or via a secondary or servo lever or other part should that for any reason be required. An example of such an indirect connection is shown in Fig. 5.

Fig. 5 shows a four-wheel braking system incorporating the invention used in a vehicle with independent suspension of all four wheels. Application of a pulling force on the inner member 36 of a first Bowden mechanism 37 connected to a wheel brake assembly 38 causes the brake of the opposed wheel brake assembly 39 to be simultaneously operated via a second Bowden mechanism 40 because the inner member of that mechanism is connected to a coupling device 41 which is connected to the conduit of the first Bowden mechanism. The operation of this part of the system is therefore in all essentials the same as the operation of the systems shown in Figs.

1 and 2. However in the Fig. 5 system, the inner member 36 is connected in alignment with or forms an extension of the inner member of a third Bowden mechanism 42 for operating the brake of a third wheel brake assembly 43. The conduit of that mechanism passes through the passageway in a second coupling device 44 which is in turn connected to the inner member 45 of a fourth Bowden mechanism 46 extending to a fourth brake assembly 47. The conduit of that mechanism passes through a third coupling device 48.

The coupling device 48 is connected by a tie 49 with a hand-brake lever 50. When a pulling force is applied to that tie by movement of the hand-brake lever, the load is transmitted via the third coupling device 48 to the fourth Bowden mechanism 46, via that fourth Bowden mechanism and the second coupling device 44 to the third Bowden mechanism 42, and via that third Bowden mechanism to the inner member of the first and second Bowden mechanisms 37 and 40.

Operation of the hand lever therefore results in simultaneous application of all four wheelbrakes. The output force, applied to each brake mechanism, is a high percentage of the input load applied to the tie 49 by the handbrake lever. The four output forces are balanced, i.e. equal to each other.

It is important to note that even in such a four-wheel brake system only one abutment extraneous to the wheel brake units is required. In the illustrated arrangement the single abutment is represented at 51. And it is only necessary to provide a single adjustment facility. In the illustrated system this facility is in the form of an adjustment nut 52 which is screwed directed onto the conduit of the third Bowden mechanism 42 and is clamped onto that conduit by the coupling device 44. The coupling devices 41 and 48 are secured to their respective conduits by suitable clamping means when the system is initially set up and such clamping means do not have subsequently to be released. The clamping means may comprise clamping screws which cause the coupling devices to grip the conduits. or end clamping plugs 53, 54 which are forced into the ends of the coupling devices.

It is not an essential feature of the invention for either the inner member of what has been described as the master mechanism, or the component herein called the tie, to be connected directly to a part to be actuated. For example such tie can be connected to a part to be actuated via a lever or via a Bowdentype mechanism.

Claims (10)

1. A mechanical remote control system wherein there is a flexible remote control mechanism (4, 37) (hereafter in subsequent claims called "master mechanism") comprising an inner force-transmitting member (3, 36) longitudinally displaceable within a conduit (5. 25), said inner member being connected at one end to an actuator (1. 50) and at its other end to a first part (9) to be actuated. and wherein a second part (14) to be actuated is connected to said conduit via a tie member (12) so as to be actuated by force which is transmitted to said conduit (5, 25) when force is applied to said inner member (3, 36) by said actuator (1, 50), characterised in that said conduit (5, 25) is connected at or near its end remote from the actuator to an abutment (8) and said tie member (12) is connected to said conduit (5, 25) by a coupling device (6, 24, 41) located at or near the other end of the conduit so that such coupling device moves towards the actuator (1, 50) when this is displaced to apply a pull force to said inner member (3, 36).

2. A system according to claim 1, wherein said tie member (12) is the inner member of a second flexible remote control mechanism (13, 40) comprising a conduit (15) in which such tie member (12) is longitudinally displaceable.

3. A system according to claim 2, wherein said first and second parts (9, 14) to be actuated are parts of braking devices mounted on independently suspended wheel support units and the adjacent ends of the conduits of the master mechanism and said second flexible mechanism are connected to abutments (22, 23) on such units.

4. A system according to claim 2 or 3, wherein the conduit (15) of said second flexible mechanism (1 3, 40) is connected at or near its end which is nearer the coupling device to a fixed abutment (16, 51) by means of an adjustment device (19) by which the operation of the entire system can be adjusted.

5. A system according to any preceding claim, wherein said coupling device (6, 24, 41) forms a passageway (27) through which the conduit (5, 25) of the master mechanism (4, 37) is threaded.

6. A system according to claim 5, wherein the conduit (5, 25) of said master mechanism (4, 37) is secured in said passageway (27) by releasable means (26) enabling the position of said coupling device (6, 24, 41) along said conduit to be adjusted.

7. A system according to claim 6, wherein the conduit (5, 25) of the master mechanism (4, 37) forms an external screw profile and an adjustment nut or nuts (26) is or are screwed dirctly onto such conduit for abutment against said coupling device (6, 24, 41).

8. A system according to any preceding claim, wherein between said actuator (1, 50) and the inner member (3, 36) of said master mechanism (4, 37) there is connected one or more devices (44, 48) by which said actuator is connected to a further part or to further parts (43, 47) to be actuated.

9. A system according to claim 8, installed for operating four vehicle wheel brakes simultaneously.

10. A mechanical remote control system substantially as herein described with reference to Fig. 1, Fig. 2 or Fig. 5 of the accompanying drawings.