ADJUSTER DEVICE FOR A CONTROL CABLE ASSEMBLY

Abstract: An adjuster device for a cable control assembly (Figure 2) has a cylindrical adjuster member (15) movable within a tubular body (14) connected to form a part of one of the elements of the cable control assembly. The adjuster member (15) is formed with two, diametrically opposed, sets of chordal teeth (16, 17) offset by a half pitch. Pawls (18) having teeth (19) and limit tabs extend through slots in the tubular body (14) and are biassed radially inwardly by C-springs (20). Applying an axial compression loading sufficient to overcome the effect of the C-springs (20) moves the pawls radially outwardly and the adjuster member is enabled to ratchet, in half tooth pitch steps, axially inwardly. The teeth are formed with radial plane flanks to prevent axial outward movement. Initial and re-setting are achieved by manually rotating the adjuster member (15) through 90° to dis-engage the teeth, withdrawing the adjuster member and tubular body (14) to a maximum extension and then re-engaging the teeth. Teeth (26) on the adjuster member (15) prevent withdrawing the adjuster member to a position out of engagement with the pawls (18).

Description: This invention relates to an adjuster device for a control cable assembly such as is utilised in conjunction with controls for automobile automatic transmissions, parking brakes, clutches, cruise control devices and gear shift devices. In US Patent specification No. 3 710 645 there is disclosed an adjuster device for a control cable assembly having cable and conduit elements including a cylindrical adjuster member movable within a tubular body connected to form a part of one of the elements to effect adjustment of the relative length thereof, the cylindrical adjuster member being formed with a longitudinally extending set of chordal teeth and the tubular body being formed with an axial slot having extending therethrough a pawl formed on a radially inner face thereof with teeth, the pawl being resiliently biassed radially inwardly to urge the teeth on the pawl into engagement with the chordal teeth on the cylindrical adjuster member, the teeth being shaped and arranged to co-act together to permit incremental movement of the adjuster member relative to the cylindrical tubular body in one direction by forcing the pawl radially outwardly against the resilient bias to dis-engage the teeth and to prevent such movement in the opposite direction. By the present invention there is provided an adjuster device for a control cable assembly in which the cylindrical adjuster member is formed with a further longitudinally extending set of chordal teeth diametrically opposed to the longitudinally extending set of chordal teeth, the tubular body is formed with a further axial slot diametrically opposed to the axial slot, the further axial slot having extending therethrough a futher pawl formed on a radially inner face thereof with teeth, biassing means common to the pawl and the further pawl resiliently biassing the pawl and the further pawl respectively radially inwardly to urge the respective teeth into engagement with the associated set of chordal teeth, the axial location of full engagement between the teeth on the pawl and the set of chordal teeth on the cylindrical adjuster being displaced axially by a distance corresponding to half of a pitch of the teeth from the axial location of full engagement between the teeth on the further pawl and the further chordal teeth to permit incremental movement in steps of a half of a pitch of the teeth of the tubular body relative to the cylindrical adjuster member in the one direction with the pawl and further pawl being forced alternately radially outwardly against the common resilient bias to dis-engage the respective teeth. The invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a partly sectioned longitudinal plan view of a portion of a cable control including an adjuster device; Figure 2 is a sectioned elevation of the cable control adjuster device on an enlarged scale taken along the line II-II in Figure 1; Figure 3 is a sectioned elevation taken along the line III-III in Figure 2; Figure 4 is a sectioned elevation taken along the line IV-IV in Figure 2; Figure 5 is a sectioned elevation similar to Figure 4 but showing the relative position of parts during resetting; Figure 6 is a plan view of a pawl; Figure 7 is an elevation of the pawl shown in Figure 6; Figure 8 is a fragmentary view an enlarged scale of the teeth of the pawl; Figure 9 is a fragmentary view of one of the members of the device; and Figure 10 is a partly sectioned view of an alternative arrangement of an adjuster device. Referring to Figure 1, a cable control system embodying the invention includes a conduit 10 which is attached at one end to a body 11 for attachment as by a tab 12 to a fixed point and a cable 13 extending through the conduit 10. A plastic tubular body 14 is attached to the other end of the conduit 10. A generally cylindrical adjuster member 15 is positioned within the tubular body 14 and is provided with diametrically opposed sets of longitudinally spaced ratcheting teeth 16, 17 which are engaged by aligned teeth 19 formed on pawls 18 located in slots in the tubular body 14, each tooth having a radial plane flank and an inclined plane flank. The pawls 18 are resiliently biassed radially inwardly by generally C shaped springs 20 positioned in grooves 21, 22 in each pawl 18 (Figures 6, 7). The pawls 18 include peripheral tabs 18A for facilitating assembly by restricting radially inward movement of the pawls 18 in the slots. The springs 20 are retained in position circumferntially to maintain the desired spring force by means of a radial projection 23 on the tubular body 14, the projection 23 being positioned circumferentially an equal distance from the pawls 18 such that the C-shaped springs 20 maintain an equal force on th pawls 18. The adjuster member 15 has opposed arcuate smooth surfaces 24, 25 such that when the tubular body 14 is rotated relative to the adjuster member 15 to the position shown in Figure 5 the teeth 16, 17 are disengaged from the pawls 18 permitting longitudinal movement of the tubular body 14 relative to the adjuster member 15 to reset the effective length of the conduit. Referring to Figure 9, the teeth 16 on the adjuster member 15 are offset longitudinally relative to the teeth 17 by an amount X equal to half of the pitch of the teeth so that, in any ratcheting action, an increment of a half pitch increment adjustment is possible since the sets of teeth 19 on the respective pawls 18 are aligned and only one set of teeth are required to be in full engagement with the teeth 16 or the teeth 17 to transmit the loading in contrast to a full pitch increment as would be the case if teeth 16, 17 were aligned. Alternatively, as shown in Figure 10, the pawls 18 may be positioned within respective sets of teeth arranged with a longitudinal offset of a half pitch relative to one another and teeth 16, 17A on the adjuster member 15 in longitudinal register. As shown in Figure 8, the teeth on either the pawls or the adjuster member 15, or both have flattened heads to facilitate initiation of ratcheting at a predetermined loading. Teeth 26 at the end of the adjuster member 15 within the tubular body 14 extend around the full circumference to act as a stop to prevent inadvertent axial disengagement of the pawls 18 and the adjuster member 15, when the tubular body 14 is rotated relative to the adjuster member 15 to the position shown in Figure 5 in order to adjust the device to a maximum extension by moving the tubular body 14 and the adjuster member 15 apart axially. A flexible seal or boot 27 is provided over the pawls and the ratcheting teeth as a protective covering. In operation, the cable control system is installed with the conduit 10 extending, in a curved run, between a pair of brackets fixed in space relative to each other. The cable 13 connects, in spring loaded tension, input and output actuation means such that linear movement at the input means produces axial movement of the cable and a corresponding linear movement at the output actuation means. As part of the installation process, or, during service in which wear of components has occurred, it is necessary to adjust the effective length of the cable to ensure that a full range of linear movement is attainable at the input and output actuation means. This is achievable manually by adjusting the relative position of the brackets or by altering attachment points on the cable. However, this is not always satisfactory and the arrangement of the present invention provides for automatic adjustment. As shown, in order to obtain automatic lengthening of the effective length of the cable 13, the system is installed with the adjuster member 15 fully extended from the tubular body 14 with the pawls 18 adjacent the teeth 26 and engaging the teeth 16, 17. Upon first placing a loading on the input actuation means tension is placed on the cable 13 to produce movement at the output actuation means. If such movement is restricted by virtue of the output actuation means engaging a limit stop, continued loading of the input actuation means will produce additional tension in the cable, thereby producing an additional compression loading in the conduit 10. Such compression loading is transmitted through the tubular body 14 and the adjuster member 15 across the inclined flanks of the teeth 16, 17 and 19 as a force having radial and axial components. The radial component is reacted by the springs 20 which deflect outwardly until the pawls are urged outwardly to such an extent that the teeth 16,17 are able to ride, or ratchet, over the adjacent teeth 19. The adjuster member 15 then moves axially inwardly of the tubular body 14 by a distance equivalent to a half of a pitch of the teeth, causing the compression, and thus radial, loading to decrease such that the springs urge the teeth 16, 17 back into engagement with the teeth 19. This movement is repeated until the input actuation means also encounters a limit stop thereby preventing further movement of the input actuation means and hence the production of additional tension within the cable 13. It will be appreciated that movement of the adjuster member 15 axially inwardly of the tubular body 14 is in a series of steps each equal to a half of a pitch of the teeth and that engagement is alternately between the teeth 16 and the teeth 19 and between the teeth 17 and the teeth 19. This arrangement enables the adjustment in the effective length of the cable 13 in relatively small increments such that, in the final position, an adjustment closely approximating to a precise adjustment is achieved. By utilising the arrangement of the teeth 16 being displaced axially by a half pitch from the teeth 17, the teeth are enabled to be dimensioned to have a flank depth and root width giving adequate strength by utilising a coarse pitch whilst retaining the restricted incremental adjustment steps of teeth at a pitch of half that dimension. Movement of the adjuster member relative to the tubular body in a direction opposed to the direction of adjustment movement when the teeth are engaged is prevented by virtue of the radial flanks on the respective teeth abutting. The loading at which the teeth ratchet is determined by the resilience of the springs 20 and may be varied by replacing the springs 20 with springs of an appropriately different resilience. Where it is required to re-set the system following replacement or adjustment of the input or output actuation means, the tubular body 14 and the adjuster member 15 are held manually, twisted through 90°, the one relative to the other, to dis-engage the teeth 16, 17 from the teeth 19, pulled apart axially to the fully extended position with the pawls 18 adjacent the teeth 26 and twisted again through 90° to re-engage the teeth 16, 17 and the teeth 19. The manner of operating the arrangement shown in Figure 10 is exactly the same as that described above, the only difference being one of construction. It will be appreciated that other configurations of control cable and loading thereof can be accommodated. Thus the device can be positioned at an intermediate location on the conduit. In a system in which the conduit serves to resist a tension force, the inclined flanks of the teeth may be positioned appropriately to permit the tubular body to move axially toward the adjuster member. Alternatively, where it is desired to adjust the actual length of the cable and thereby adjust the effective length of the conduit, the tubular body and the adjuster member are connected into the cable run with the conduit having an enlarged portion to accommodate the tubular body and adjuster member or the tubular body and adjuster member being positioned at the end of the cable run adjacent and beyond an end of the conduit.

Claims: 1. An adjuster device for a control cable assembly having cable and conduit elements (13, 10) including a cylindrical adjuster member (15) movable within a tubular body (14) connected to form a part of one of the elements to effect adjustment of the relative length thereof, the cylindrical adjuster member (15) being formed with a longitudinally extending set of chordal teeth (16) and the tubular body being formed with an axial slot having extending therethrough a pawl (18) formed on a radially inner face thereof with teeth (19), the pawl being resiliently biassed radially inwardly to urge the teeth (19) on the pawl (18) into engagement with the chordal teeth (16) on the cylindrical adjuster member, the teeth being shaped and arranged to co-act together to permit incremental movement of the adjuster member relative to the cylindrical tubular body in one direction by forcing the pawl radially outwardly against the resilient bias to dis-engage the teeth and to prevent such movement in the opposite direction, characterised in that the cylindrical adjuster member (15) is formed with a further longitudinally extending set of chordal teeth (17) diametrically opposed to the longitudinally extending set of chordal teeth (16), the tubular body is formed with a further axial slot diametrically opposed to the axial slot, the further axial slot having extending therethrough a futher pawl (18) formed on a radially inner face thereof with teeth (19), biassing means (20) common to the pawl and the further pawl resiliently biassing the pawl and the further pawl respectively radially inwardly to urge the respective teeth into engagement with the associated set of chordal teeth, the axial location of full engagement between the teeth (19) on the pawl and the set of chordal teeth (16) on the cylindrical adjuster being displaced axially by a distance corresponding to half of a pitch of the teeth from the axial location of full engagement between the teeth (19) on the further pawl and the further chordal teeth (17) to permit incremental movement in steps of a half of a pitch of the teeth of the tubular body relative to the cylindrical adjuster member in the one direction with the pawl and further pawl being forced alternately radially outwardly against the common resilient bias to dis-engage the respective teeth. 2. An adjuster device for a control cable assembly as claimed in Claim 1, characterised in that the biassing means is a circumferential spring means (20) extending substantially around the tubular (14) body and engaging seats (21, 22) in radially outer faces of the pawl and the further pawl with a radially extending projection (23) on the tubular body locating the spring means thereon. 3. An adjuster device for a control cable assembly as claimed in Claim 1 or Claim 2, characterised in that the pawl and further pawl are each formed with a tab (18A) limiting radially inward movement in the associated slot. 4. An adjuster device for a control cable assembly as claimed in any preceding claim, characterised in that the cylindrical adjuster means (14) is rotatable relative to the tubular body (15) to dis-engage the chordal teeth (16, 17) from the associated teeth (19) on the pawl and further pawl. 5. An adjuster device for a control cable assembly as claimed in any preceding claim, characterised in that an end portion of the cylindrical adjuster member within the tubular body is formed with a circumferential stop (26) adapted to prevent withdrawal of the cylindrical adjuster member past the pawls. 6. An adjuster device for a control cable assembly as claimed in any preceding claim, characterised in that the set of chordal teeth (16) on the cylindrical adjuster member are axially displaced by a distance corresponding to a half of a pitch of the teeth from the further set of chordal teeth (17). 7. An adjuster device for a control cable assembly as claimed in any preceding claim, characterised in that the heads of at least the chordal teeth are flat. 8. An adjuster device for a control cable assembly as claimed in any preceding claim, characterised in that the device is enclosed in a flexible seal or boot (27).

Inventors: CHACZYK, ADAM WLADYSLAW, LICHTENBERG, NORMAN BERNARD
Applicants: ACCO BABCOCK INC.
Application year: 1987
Main classification: F16C1
IPC codes: F16C1