SELF-REGULATING DEVICE FOR THE LENGTH OF THE SECURITY BRAKE CABLE OF MOTOR VEHICLES

Abstract: The self-regulating device for the length of a security brake cable of motor vehicles is comprised of a regulating mechanism (R) superimposed to the steel cable (1) which connects the actuating mechanism for the brake shoes of a rear wheel to the rocking compensation mechanism (B), as well of a control mechanism (C) arranged between the hand brake lever and said rocking mechanism (B). The regulation (R) and control (C) mechanisms are interconnected by means of a shielded steel cable (I). As a fonction of the position occupied by the brake lever, a regulation rod (30) may slide inside the main body (4) of the regulation mechanism (R), said rod (30) meeting the guide (5) of the steel cable (1) which connects said rocking mechanism (B) to the brake shoe actuation mechanism, thereby adjusting the length of the sheathed cable (1-5). Application to the car industry.

Description: The invention refers to an automobile parking brake cable length self-adjusting device, as cited in the preamble of claim 1. A similiar device is known by the document DE-A-3 101 048; this document deals with an overrun brake of a trailer, contrary to the invention which not only refers to a device for transport vehicles in general, but particularly for private passenger cars. It is further known by the document FR-A-2 244 102 to furnish the brake of a railroad vehicle with an adjusting device which always keeps the distance between the jaws of a caliper brake and the relating brake disc or between a radially operating brake shoe and the circumference of a wheel of a carriage as narrow as possible. Additionally, the document EP-A-0 342 994 discloses a selfadjusting device which is installed in the Bowden cable for operating the engine clutch of a vehicle. At a point along this Bowden cable, its sheath is severed; its ends thus formed are spreaded by the self-adjusting device. As is known, the purpose of the parking brake incorporated as original equipment in automobiles is to hold the vehicle immobile once it has been parked, even when it is parked on a steep slope. The parking brake generally acts on the rear wheels of the automobile and, in any case, the parking brake mechanical actuating device is independent of the service or foot brake actuating device. The parking brake is generally actuated manually by a brake lever which is disposed in the vehicle and connected by sheathed steel cables to the mechanisms applying the brake shoes or calipers which immobilize the vehicle on each rear wheel. Said brake lever is provided with mechanical means setting the position in which the parking brake is operative, preventing said brake lever from accidentally coming out of the braking position under normal service conditions. Said sheathed steel cables connecting the brake lever with the brake shoe or caliper actuating mechanism of each rear wheel are subject to variations of length. This causes unequal operation of the brake device, which is compensated by mechanisms on said steel cables, similiar to the mechanisms mentioned above. The known compensation mechanisms suffer, nevertheless, from notable operative drawbacks when the brake shoes or calipers are temporally seized, i.e. when said brake shoes or calipers do not return to the normnal released position until some time has passed after releasing the brake lever. This situation is frequently caused by accumulation of ice on the brake shoe or caliper actuating mechanism during extended parking of the vehicle in open air in regions where low temperatures are usual. The features of claim 1 provide a solution to the problems caused by temporary seizure of the automobile parking brake shoes or calipers under the above conditions. This solution is improved by the features of the claims 2 to 5. The automobile parking brake cable length self-adjusting device of the invention is represented in the sheets of the drawings of the present specification. In said drawings: Figure 1 is an overall view of the device of the invention. Figures 2 and 3 are views partly in section of the adjusting mechanism forming the device of the invention in different operative stages. Figures 4 and 5 are side and top views respectively of a component of the adjusting mechanism of the device of the invention. Figures 6 and 7 are side and top views respectively of a component of the adjusting mechanism of the device of the invention. Figure 8 is a bottom view of a component of the adjusting mechanism of the device of the invention. Figure 9 is a cross section view from Figure 8. Figure 10 is a top view, partly in section, of the control mechanism of the device of the invention. Detailed description of the embodiment The automobile parking brake cable length self-adjusting device described as an embodiment is formed, as shown in Figure 1 of the enclosed drawing sheets, by the adjusting mechanism R and by the control mechanism C connected together by the sheathed steel cable E . The adjusting mechanism R is mounted on the steel cable 1 connecting the brake shoe or caliper actuating mechanism of one of the rear wheels of the vehicle with the rocking device B , which is connected to the control mechanism C by the steel cable 2. In turn, the control mechanism C is connected to the brake lever by the steel cable 3, all as shown in detail in Figure 1 which, for clarity, does not show the said actuating mechanism or the brake lever. The adjusting mechanism R is formed by the main body member 4 suitably dimensioned snugly to receive mechanical actuating means MA and fixing and adjusting means FR for the length of the steel cable 1 provided with the sheath 5 comprised between the adjusting mechanism R and the said brake shoe or caliper actuating mechanism. The main body member 4 is essentially frustoconical as shown in Figures 1, 2 and 3 and is made preferably from plastics materials of appropriate mechanical properties. The main body member 4 is formed at the end facing the sheathed steel cable 1-5, with the concentric radial extension 6 provided with the tangential extension 7, shown in Figures 1, 2, 3, 8 and 9. The said tangential extension 7 is provided with a bore 8, shown in Figure 9, of stepped section which is designed to receive and fix the corresponding end of the sheath 9 of the steel cable 10, which connects the adjusting mechanism R and control mechanism C , and allows passage therethrough of said steel cable 10. At the opposite end there is the longitudinal extension 11 provided with a bore 12, shown in Figures 1, 2 and 3 and which is designed to anchor the adjusting mechanism R to the fixed point F of the vehicle structure. In this embodiment the longitudinal extension 11 is cylindrical and, logically, may have any other form which is appropiate for each particular application. The interior of the main body member 4 is formed, at the said end facing to the sheathed steel cable 1-5, with a cylindrical portion 13 having a transverse cavity 14 concentric therewith and which is coextensive with the radial extension 6 as shown in detail in Figure 9 and which is designed snugly to receive the mechanical actuating means MA . Linking with the said cylindrical portion 13 and transfer cavity 14 and correlatively therewith, the interior of the main body member 4 is formed with a frustoconical portion 15 and a cylindrical portion 16 designed snugly for receiving mechanical fixing and adjusting means FR . The mechanical actuating means MA is constituted by the base member 17, by the thrust disc 18 and by the spring 19 which are mutually engageable as shown in Figures 1, 2 and 3. The base member 17 and the thrust disc 18 are preferably made from plastics materials of appropriate mechanical properties. The base member 17 which, as shown in Figures 1, 2 and 3, acts as a cover for the main body member 4, is essentially cylindrical and is formed with a concentric radial extension 20 and a longitudinal centered extension 21 the free end of which is frustoconical in 22 as shown in Figures 6 and 7. Said base member 17 has a longitudinal central bore 23. Figures 6 and 7 show also how the surface of the base member 17 facing the interior of the main body member 4 is formed in this embodiment with three radial slots 24 having corresponding sliding planes 25. Figures 4 and 5 show how the thrust disc 18, which is essentially cylindrical, is provided with two retaining projections 26 which allow the firm connection of the corresponding end of the steel cable 10 which, as said above, connects the adjusting mechanism R and control mechanism C together, by way of the corresponding through holes 27. The thrust disc 18 is formed on the surface facing the base member 17 with three radial ribs 28 which mate positionally and dimensionally with the radial slots 24 and sliding planes 25 formed on the said base member 17, so that they may snugly engage together and disengage by means of the said sliding planes. The thrust disc 18 is also provided with the centered through hole 29 through which the longitudinal centered extension 21 of the base member 17 may slide snugly, as shown in Figures 1, 2 and 3 of the drawing sheets. The spring 19 shown in Figures 1 and 2 is disposed coaxially around the steel cable 10 which, stripped of its sheath, is in the interior of the main body member 4 received in the transverse cavity 14 so that, with the steel cable 10 being connected to the thrust disc 18 by the retaining projections 26, the spring 19 permanently presses against the thrust disc 18 and against the wall of the transverse cavity 14 through which the steel cable 10 may slide. The mechanical fixing and adjusting means FR is constituted by the adjusting rod 30, by the jaws 31 provided with the linking spring 32, by the release member 33, by the release spring 34 and by the adjusting spring 35, as shown in detail in Figures 1, 2 and 3. The adjusting rod 30, which as shown in Figures 1, 2 and 3, may slide through the main body member 4, is provided with a suitably dimensioned longitudinal bore through which the steel cable 1 linking, as said before, the brake shoe or caliper actuating mechanism of the rear wheel with the rocking device B may slide. Said adjusting rod 30 is firmly attached at one end thereof by the terminal 36 to the corresponding end of the sheath 5 of the steel cable 1 the length of which is to be adjusted. In this embodiment the adjusting rod 30 is formed externally with a screw thread 37 extending along the whole length thereof. Logically, the length of the screw thread 37 may vary depending on each particular application. The jaws 31, of which there are three in this embodiment, are snugly received, as shown in Figures 1, 2 and 3, in the frustoconical portion 15 formed in the interior of the main body member 4, such as to define an essentially cylindrical longitudinal aperture through which the adjusting rod 30 may suitably slide. The respective ends of said aperture form corresponding essentially frustoconical portions 31a and 31b . The jaws 31 are provided on the surfaces forming the said aperture with corresponding screw threads 38 mating with the retaining screw 37 formed on the adjusting rod 30, so that they may snugly engage or disengage as shown in the amplified detailed views of Figures 3 and 2 respectively. In this embodiment the jaws 31 are connected together by the linking spring 32 which is designed to keep the preset distribution of the latter in the frustoconical portion 15 constant while they move therethrough. The release member 33 and release spring 34 are received, as shown in Figures 1, 2 and 3, in the cylindrical portion 16 formed in the interior of the main body member 4. The release member 33 is essentially cylindrical and is provided with a bore through which the adjusting rod 30 may suitably slide. At the end facing the jaws 31 it is formed with a frustoconical portion 39 mating with the frustoconical 31b formed on the jaws 31. The release spring 34 is disposed coaxially around the adjusting rod 30 and presses permanently against the wall forming the cylindrical portion 16 of the main body member 4 and against the release body 33, so that, through the frustoconical portion 39 of the release member 33 it tends to force apart the jaws 31 of the adjusting rod 30, as shown in detail in Figures 1, 2 and 3. Figures 1, 2 and 3 show how the spring 35 is disposed coaxially around the sheathed steel cable 1-5 and the adjusting rod 30 and presses permanently against the main body member 4 and, through mechanical means which for reasons similar to those given above are not shown in the drawing sheets, against the sleeve 5 of the steel cable 1, thereby adjusting the length of the sheathed steel cable 1-5. The control mechanism C is constituted by the main body member 40 which suitably dimensioned may snugly receive the mechanical control means G for the actuation of the adjusting mechanism R depending precisely on the position of the parking brake lever. The main body member 40 is essentially parallelepipedic as shown in Figures 1 and 10 and is made preferably from plastics materials having appropriate mechanical properties. In this embodiment it is provided with four elongated holes 41 for anchorage thereof to a fixed point on the automobile structure. This fixed point has not been shown in the sheets of drawings for reasons similar to those given above. Figures 1 and 3 show how the main body member 40 is formed in the interior thereof with the longitudinal cavity 42. Both ends are provided with respective bores 43 and 44 through which the steel cables 2 and 3 may respectively suitably slide. It is also provided with the transverse cavity 45, one end of which is provided with the bore 46 provided with a screw thread. Figures 1 and 10 show how the mechanical command means G received in the main body member 40 are formed by the thrust member 47, by the draw member 48 and by the adjusting rod 49. The thrust member 47, which in this embodiment is essentially parallelepipedic in shape, is snugly received in the longitudinal cavity 42 through which it may slide in a sufficient distance. It is attached at one of the longitudinal ends thereof to the steel cable 2 connecting with the rocking device B . In this embodiment the thrust member 47 is provided with the sliding surface 50 formed on the end receiving the steel cable 3 which connects with the brake lever. The draw member 48, which in this embodiment is essentially parallelepipedic in shape is snugly received in the transverse cavity 45 in which it may slide over a sufficient distance. It is attached at one of the ends thereof to the corresponding end of the steel cable 10 which, at the other end thereof, is attached, as said above, to the thrust disc 18 forming the mechanical actuating means MA of the adjusting mechanism R . The draw member 48 is provided with the bore 51 through which the thrust member may snugly slide. Said draw member 48 is provided with the bearing 52 so that the sliding of thrust member 47 through the draw member 48 causes the latter to move through the transverse cavity 45 as shown in Figure 1 and 10. For manual adjustment of the length of the sheathed steel cable E connecting the adjusting mechanism R with the control mechanism C the corresponding end of the sheath 9 of the steel cable 10 is firmly attached to the adjusting rod 49 by way of the terminal 53 as shown in Figures 1 and 3. The adjusting rod 49, which is provided with a bore through which the steel cable 10 may suitably slide, is provided on the outer surface thereof over a sufficient length with a screw thread mating with the screw thread provided in the bore 46 of the transverse cavity 45 of the main body member 40 so that the adjusting rod 49 may be inserted in the transverse cavity 45 to the distance required by the adjustment of the length of the sheathed cable E in each particular application. The position of the control rod 49 is set once the necessary length of the sheathed cable E has been determined, by the two nuts 54 which are designed to prevent the unscrewing and consequent misadjustment of the adjusting rod 49. The automobile parking brake cable length self-adjusting device of the invention described here as an embodiment operates as follows: Figures 1 and 2 show the positions occupied by the components of the mechanical means forming the adjusting mechanism R and control mechanism C when the parking brake is released, in other words, when the brake lever is in the released position. Under these conditions, the adjusting rod 30 of the mechanical fixing and adjusting means FR may slide freely through the main body member 4 of the adjusting mechanism R , and may occupy any intermediate adjusting position of the length of the sheathed steel cable 1-5 connecting the corresponding vehicle rear wheel brake shoe or caliper actuating mechanism with the adjusting mechanism R , the adjusting position being determined by the mechanisms of the parking brake device and by the action of the adjusting spring 35 of the mechanical fixing and adjusting means FR . Under these conditions, the combined action of the release member 33 and of the release spring 34 of the mechanical fixing and adjusting means FR and the frustoconical shape 22 of the free end of the longitudinal centered extension 21 of the base member 17 of the actuating mechanism MA , prevent the jaws 31 from acting on the adjusting rod 30, since said jaws 31, due to the said combined action may slide away from adjusting rod 30 along the frustoconical portion 15 formed on the interior of the main body member 4, which sliding is possible in turn due to the position occupied by the thrust disc 18 of the actuating means MA which is attached by the steel cable 10 to the control mechanism C . Figures 3 and 10 show the positions occupied by the said mechanical means of the adjusting mechanism R and the control mechanism C , respectively, when the parking brake is applied, in other words, when the brake lever is in the braking position. Under these conditions the adjusting rod 30 is blocked due to the action of the jaws 31, and in this way the length of the sheath steel cable 1-5 is fixed. Under these conditions, the thrust disc 18, which is actuated by the steel cable 10, is moved over sufficient distance and moves in turn the jaws 31 across the frustoconical portion 15 of the main body member 4 to the position in which the threads 37 and 38, formed on the adjusting member 30 and the jaws 31 respectively, are blocked together, thereby preventing any movement of the adjusting rod 30.

Claims: An automobile parking brake cable length self-adjusting device comprising an adjusting mechanism (R) attached to a fixed point (F) of the vehicle structure and provided with mechanical means (FR) setting and adjusting the length of a sheathed main steel cable (1-5) connected to the adjusting mechanism (R), characterized in that the adjusting mechanism (R) is formed by an essentially frustoconical hollow basic body member (4) of sufficient size conveniently to receive mechanical actuating means (MA), which are firmly connected to a control mechanism (C) by way of an additional sheathed steel cable (E) connecting the adjusting (R) mechanism and the control (C) mechanism, and the mechanical means (FR) comprised between the adjusting mechanism (R) and the actuating mechanism of the brake shoes or caliper of the corresponding rear wheel, and said basic body member being formed at the one end facing the actuating mechanism with a concentric radial extension (6) provided with a tangential extension (7) having a bore (8) of stepped section so dimensioned that the additional steel cable (E) devoid of its sheath (9) may suitably slide therethrough, the corresponding end of said sheath (9) being firmly fixed at said basic body member (4), and at the other end with a longitudinal extension (11) which is so dimensioned and shaped as to allow the attachment of the adjusting mechanism (R) to said fixed point (F) of the vehicle structure, the interior of the basic body member (4) at said one end with a cylindrical portion (13) connected to a transverse cavity (14) concentric therewith, which is coextensive with said concentric radial extension (6), said cylindrical portion (13) and transverse cavity (14) snugly receiving the mechanical actuating means (MA), and, as an extension to the cylindrical portion (13) and correlative therewith, a frustoconical portion (15) and a further cylindrical portion (16) snugly receiving said mechanical fixing and adjusting means (FR). Device as claimed in claim 1, characterized in that the mechanical actuating means (MA) are constituted by an essentially cylindrical base member (17) having a concentric radial extension adapted and snugly close as a lid the corresponding end of the basic body member (4) and to couple therewith, the side of the base member (17) being disposed in the interior of said basic body member (4) being formed with a number of radial slots (24) and with a longitudinal centered extension (21) the free end (22) thereof being essentially frustoconical, said base member (17) being provided with a centered longitudinal bore (23) slidingly receiving the members (30, 37) constituting the mechanical fixing and adjusting means (FR), an essentially cylindrical thrust disc (18) is provided with a longitudinal through bore (29) slidingly receiving said longitudinal extension (21), the surface of the thrust disc (18) facing the base member (17) being provided with radial ribs (28) conforming in number and size with the radial slots (24) formed on the base member (17) for the mutual snug engagement and disengagement, the thrust disc (18) being provided with retaining projections (26) firmly attachable to the additional steel cable (E), and a spring (19) is housed in the transverse cavity (14) and permanently bears against the thrust disc (18) as well as against the corresponding wall of said transverse cavity (14), thus, when expanded, establishing the position in which the thrust disc (18) and the base member (17) are closest to each other. Device as claimed in claims 1 and 2, characterized in that the mechanical fixing and adjusting means (FR) are constituted by an adjusting rod (30), one end thereof being firmly attached to the sheath (5) of the main steel cable (1-5), said adjusting rod (30) having a longitudinal through bore slidingly receiving the core (1) of said main steel cable (1-5), and by an external retaining screw thread formed on the outside of the adjusting rod (30), clamping jaws (31) are provided with retaining screw threads (38) mating with said external screw thread, an essentially conical release member (33) is provided with a bore slidingly receiving the adjusting rod (30), a release spring (34) is provided coaxially with the adjusting rod (30) and permanently presses against the main body member (4) and the release member (33); and an additional spring (35) is coaxially disposed about the sheath (5) of the main steel cable (1-5) and permanently bears against the basic body member (4) and said sheath (5), thus adjusting the length of said sheathed main steel cable (1-5). Device as claimed in claims 1 to 3, characterized in that the control mechanism (C) is constituted by an essentially right parallelepipedic main body member (40) which is internally formed with an longitudinal through recess (42) and a transverse recess (45), which snugly and silidingly receive members (47, 48, 49) of a command mechanism (G) while yacting coordinately, said transverse recess (45) being provided with a through hole (46) which may be retainingly screw threaded. Device as claimed in claim 4, characterized in that the command mechanism (C) is constituted by a thrust member (47) received in said longitudinal through recess (42) and is firmly attached to the main steel cable (2, 3), a draw member (48) is housed in said traverse recess (45), is firmly attached to the corresponding end of the additional steel cable (E) connecting it to the the thrust disc (18) and is formed with a through hole slidingly receiving said thrust member (47) which causes a longitudinal movement of the draw member (48), and an adjusting rod (49) may be screw-threaded on its outside, is at one end firmly attached to one end of the sheath (9) of the additional steel cabel (E) and is provided with a through hole slidingly receiving the core (10) of said additional steel cable (E), thus allowing the adjustment and setting of the length of the additional sheathed cable (E).

Inventors: ROCA CABESTANY AGUSTIN, SOLANO SALLAN VICTORINO, ROCA CABESTANY, AGUSTIN, SOLANO SALLAN, VICTORINO
Applicants: FICO CABLES SA, FICO-CABLES, S.A.
Application year: 1991
Main classification: F16C1
IPC codes: F16D65, B60T11, F16C1, B60T7