MECHANICAL CABLE CONTROL ADJUSTMENT DEVICE AND METHOD FOR THE INITIAL ADJUSTMENT THEREOF

Abstract: A manually operable member 15 (Fig 1) on a connector 5 is rotatable to effect engagement between detents 12 and an end portion 4 of a cable conduit 2. In the disengaged position, a spring 11 urges the device to an expanded configuration thereby enabling an initial tension to be placed in a cable core 1 following connection between a vehicle clutch fork 6 and pedal 8 - which is urged against a stop 10 - and anchorage of the conduit. Following engagement of the detents 12 with the end portion 4 of the conduit to form a rigid connection, upon compressing the conduit by pushing down the pedal 8 a termination 22 is moved fully into the connector 5, thereby decreasing the effective length of the conduit by a pre-determined amount J. Upon releasing pressure on the pedal 8, the pedal returns to a rest position spaced from the upper stop 10. This initial spacing permits the accommodation of clutch lining wear over a greater range before the pedal contacts the upper stop as a result of the wear and there is insufficient effective travel of the pedal for clutch dis-engagement.

Description: This invention relates to a mechanical cable control device arranged to connect a member to be actuated with an actuating member, such as a motor vehicle clutch and a clutch pedal in which a length of cable core is axially movable in a cable conduit having first and second consecutive conduit sections the adjacent ends of which are provided respectively with co-axial first and second connector structures axially movable the one within the other, a spacer spring acting between the first and second connector structures, and manually actuated locking means for fixing the first and second connector structures the one relative to the other. A device of this type is described in EP224399A. With such a device, by connecting to the actuating member and to the member to be actuated the ends of the cable which project on either side of the opposite ends of the conduit sections anchored in corresponding fixed supports, the device is set to the appropriate length automatically in situ under the effect of a spacer spring, after which the locking means are used to fix the connector structures to one another in the relative position thus obtained, without the need for adjustment work at the connection between the ends of the cable and the actuating member or member to be actuated. However, where clutches for motor vehicles are concerned, these are subjected to progressive wear which appreciably alters the geometry of the kinematic chain between the actuating meber and the member to be actuated. In particular, when the clutch lining is new, the clutch fork can execute an angular movement greater than that available at the outset at the time of the initial adjustment of the mechanical control. This is not true of the clutch pedal which has a range of movement determined once and for all by its lower stop, when the pedal is completely pressed down, and by its upper stop, towards which the pedal returns in the rest position. Consequently, in proportion as the clutch linings become worn, the cable, tensioned in the configuration required at the time of the initial adjustment, cannot adjust progressively, in relation to the movement of the clutch fork, accompanying the clutch lining wear because of the above-mentioned upper stop, so that when the actuating pedal is released the clutch no longer re-engages correctly, thereby leading to a substantial reduction in the useful life of the clutch. It is an object of the present invention to provide a cable-type mechanical control device with initial manual adjustment means but which overcomes such a disadvantage, without increasing the production costs of the device, at the same time ensuring that the facility of initial adjustment to the latter continue to be simple and accurate. To achieve this, according to one feature of the invention, the mechanical control device includes a connecting means movable between an extended initial position and a retracted position connecting the two elements of the pair consisting of the first connector structure and the adjacent end of the first conduit section associated with it. Another object of the present invention is to provide a method for the initial adjustment of such a cable-type mechanical control, which is simple and effective to use and which makes it possible to ensure that the equipment associated with the member to be actuated functions correctly, even in the event of a change in the geometrical operating parameters of the member to be actuated. To achieve this, according to a feature of the invention, this method of initial adjustment, involving the prior steps of connecting the cable to the actuating member and to the member to be actuated, automatically setting the mechanical control device to the appropriate length under the effect of the spacer spring and then using the locking means to fix the connector structures firmly to one another in the position thus obtained, is characterized in that it comprises the subsequent step of actuating the actuating member in order to actuate the member to be actuated, thereby tensioning the cable so as to bring the connecting means into its retracted configuration as a result of reaction in the conduit. By means of such an arrangement and such a method of adjustment, the presetting of the mechanical control device to an appropriate length actually corresponds to temporary initial preadjustment, and the subsequent step of actuating the actuating member, causing the retraction of the connecting means and therefore a shortening of the conduit in relation to the preadjustment position, results in the provision of a slight excess length of cable, thus allowing the actuating member to move a specific distance away from its upper stop, whilst nevertheless keeping the cable correctly tensioned, so that, in proportion as the clutch becomes worn, the cable may accompany the corresponding movement of the clutch fork, before finally coming up against its upper stop, thereby enabling an appropriate re-engagement of the clutch even when the wear of the clutch lining is considerable. The invention will now be described by way of example with reference to the accompanying, partly diagrammatic, drawings in which:- Figure 1 is a view in longitudinal section of a mechanical cable control adjuster device in which the lower half shows the device in a configuration of initial preadjustment with manually actuable locking means in an engaged position and the upper half shows the device in a configuration of final initial adjustment but with the manually actuable locking means in a dis-engaged position; and Figure 2 is a cross-sectional view in the sectional plane II-II through the two parts of Figure 1. As shown the cable control device includes an actuating cable core 1 axially movable within two axially distinct consecutive flexible conduit portions 2, 3, with the portion 2 having an end portion 4 bared to expose indented convolutions of a wound wire casing of the conduit slidably extending into a cylindrical connector 5. The cable core 1 is connected at one end to a vehicle clutch fork provided with a tension spring 7 and at the other end to a clutch pedal 8 provided with a tension spring 9 urging the pedal towards an upper stop 10. The ends of the conduit sections 2 and 3 remote from the connector 5 are anchored respectively in relative stationary structures on the vehicle (not shown). Initial adjustment means for the device include a spacer spring 11 urging the connector 5 axially away from the conduit portion 2 and manually actuable locking means comprising detents 12 each having on a radially inner face teeth corresponding in pitch to the indented convolutions of the conduit casing and being guided slidably in a radial slot 13 in the connector 5. The radially outer end 14 of each detent 12 has the form of a section of a frustum of a cone arranged to co-act with a cam surface of corresponding profile of an operating member 15 formed as two, snap together, parts mounted rotatably and slidably on the connector 5. The spacer spring 11 acts between an end face of the operating member 15 and a collar 17 crimped on to the conduit portion 2 and a flexible boot 18 is provided between the ring 17 and the operating member 15 to prevent the ingress of deleterious matter into the device. An O-ring seal is provided between connector 5 and the operating member 15 to a similar purpose. The operating member 15 is formed internally with a frusto-conical cam surface 19 having diametrically opposed axial extensions 20 corresponding in width to the detents 12, the remainder of the cam surface 19 abutting radial shoulders 21 formed on the interior of the operating member 15. In a dis-engaged position, shown in the upper half of Figure 1, the detents 12 are seated respectively on the radial shoulders 21. Upon manually rotating the operating member 15 to bring the detents 12 into register with the axial extensions 20, as shown in the lower half of Figure 1, the spring 11 urges the operating member 15 axially away from the conduit portion 2 to seat upon a radial shoulder 16 formed upon the connector 5 whilst, at the same time, causing the detents 12 to move radially inwardly by the inter-action of the axial extensions 20 of the frusto-conical cam surface 19 and the outer ends 14 of the detents 12, thereby affecting full and rigid engagement of the teeth with the indented convolutions of the wire wound conduit. The conduit portion 3 is provided with a termination 22 having a cylindrical end portion 23 of an outside diameter corressponding to the inside diameter of the connector 5 and is formed with an annular bead 25 and an end collar 24. In an initial assembled configuration of the control cable device, the end portion 23 of the termination 22 extends only partially into the connector 5, the bead 25 seating on an end face 26 of the connector 5. On installation, the cable control device is appropriately positioned within the bodywork of the vehicle, the respective ends of the cable core 1 connected to the clutch fork 6 and the pedal 8 and the outer ends of the conduit portions 3,5 anchored to the bodywork. To effect initial adjustment, the operating member 15 is then moved manually to compress the spring 11 such that the detents 12 register with the radial shoulders 21 and is rotated so as to put the detents 12 into the dis-engaged position, the spacer spring 11 then ensuring that the device is set to the appropriate length under the effect of the force transmitted to the connector 5 by the effect of the spring 11 acting between the collar 17 on the conduit portion 2 and the operating member 15, the detents 12, the connector 5 and the termination 22 on the conduit portion 3 fully to extend the device such that with the clutch fork in the engaged position, the cable core 1 is tensioned to move the pedal against the upper stop 10, the spring 7 being considerably stronger than the spring 9. The operating member 15 is then rotated to bring the diametrically opposed extensions 20 of the frusto-conical surface 19 into register with the detents 12, whereupon the action of the spacer spring 11 urges the operating member 15 toward the conduit portion 3. The outer ends 14 of the detents 12 then co-act with the extensions 20 of the frusto-conical surface 19 to urge the detents radially inwardly such that the teeth formed on the inner faces engage with the indented convolutions of the conduit portion 2 and thereby form a rigid connection between the conduit portion 2 and the connector 5. Following initial adjustment, the pedal 8 is then pushed down to the full extent to move the clutch fork to a dis-engaged position. The resulting tension in the cable core 1 generates, between the two conduit portions 2 and 3, a substantial compressive force urging the termination 22 into the connector 5 sufficient to overcome the initial stop between the bead 25 and the shoulder 26, this penetration taking place over a distance J, until the radial shoulder 24 bears firmly against the radial shoulder 26, this configuration subsequently being maintained, as a result of the frictional force fit between the bead 25 and the connector 5. The reduction by the distance J in the length of the cable conduit restores a corresponding length to the cable core 1 which is taken up by the tensioning spring 9, to bring pedal 8 to a rest position spaced by a small amount (not detectable by the user) from the upper stop 10, in order, as mentioned above, to accommodate the change in the relative axial position of the cable core 1 accompanying compensation for wear of the clutch lining.

Claims: 1. Mechanical cable control adjustment device comprising a cable (1) intended to be connected to an actuating member (8) and to a member to be actuated (6) and sliding in a cable conduit consisting of a first and a second consecutive conduit section (2, 3), the adjacent ends of which are extended respectively by a first and a second connector structure (4, 5) associated telescopically with one another, a spacer spring (11) between the first and second connector structures, and manually actuated locking means (12) for fixing the first and second connector structures to one another, characterized in that it comprises a connecting means (22, 26) movable between an extended configuration and a retracted configuration connecting the two elements of the pair consisting of the second connector structure (5) and of the adjacent end of the second conduit section (3). 2. Device as claimed in Claim 1, characterized in that the retractable connecting means comprises a termination member (22) associated with one (3) of the elements of the said pair and having first and second stop means (25, 24) located at an axial distance from one another and designed to interact successively by engagement with the other element (5) of the said pair, the first stop means (26) being movable under the effect of a relative compressive force between the two elements of the said pair, in order to make the second stop means (24) interact with the other element (5) of the said pair. 3. Device as claimed in Claim 2, characterized in that the termination member (22) is received telescopically in one end of the second connector structure (5), the first and second stop means consisting of first and second stop surfaces (25, 24) projecting radially and capable of interacting with a complementary stop surface (26) of the second connector structure (5). 4. Device as claimed in Claim 3, characterized in that the termination member (22) comprises a cylindrical end portion (23) of a diameter corresponding to the internal diameter of the second connector structure (5) and ending in a radial shoulder (24) forming the second stop surface, the cylindrical end portion (23) having, in an intermediate zone, a bead (25) forming the first stop surface and capable of being urged into the second connector (5), the complementary stop surface (26) being formed by an annular surface at the end of the second connector (5). 5. Device as claimed in any preceding claim, characterized in that locking means (12) are carried by the second connector structure (5) and are arranged to interact by engagement with the first connector structure (4) extending within the second connector (5). 6. Device as claimed in Claim 5, characterized in that the locking means consist of at least one locking element (12) radially movable in the second connector structure (5) and actuable by means of a cam (20) formed on an operating member (15) carried by the second connector structure. 7. Device as claimed in Claim 6, characterized in that a spacer spring (11) bears on the operating member (15). 8. Device as claimed in Claim 6, characterized in that the cam (20) is formed on an inner angular sector portion of the operating member (15). 9. Device as claimed in any preceding claim, characterized in that the first connector structure (5) is formed by a bared end of the second conduit section (3). 10. Method of effecting initial adjustment mechanical cable control according to any preceding claim, including the steps of connecting the cable (1) to an actuating member (8) and to a member to be actuated (6), setting the device to the appropriate length under the effect of a spacer spring (11) and then using locking means (12) to fix the first and the second connnector structures (4,5) firmly to one another in the relative position thus obtained, characterized in that it comprises the subsequent step of actuating the actuating member (8) in order to actuate the member to be actuated (6), as to bring the connecting means (22, 26) into the retracted configuration as a result of the reaction in the conduit (2, 3).

Inventors: GUIDECELLI, CHARLES
Applicants: ACCO CABLE CONTROLS LIMITED
Application year: 1987
Main classification: F16C1
IPC codes: F16C1, F16D13