FR2856359A1 - PARKING BRAKE COMPRISING AN EMERGENCY RELEASE DEVICE - Google Patents

Abstract

The present invention relates mainly to an emergency release device, in particular of the parking brake type provided with an activation actuator. The subject of the invention is a device (71) for emergency release of the parking brake. according to the present invention comprising means (73) for pushing on a key for locking and / or locking the parking brake in the activated condition. The present invention applies in particular to the automotive industry. The parking brake according to The present invention applies mainly to the braking industry for motor vehicles, in particular for passenger vehicles.

Description

PARKING BRAKE COMPRISING AN EMERGENCY RELEASE DEVICE

  The present invention relates mainly to an emergency unlocking device, in particular of the parking brake type provided with an activation actuator.

  Patent application FR 02 15244, not published on the date of filing of this application, describes a parking brake that can be activated by a pressurized fluid with mechanical locking. It is extremely important to be able to deactivate such a brake to allow the vehicle to restart or, at least, to be able to move the vehicle.

  Unlocking the brake can be problematic if the vehicle's electrical and / or hydraulic system fails.

  It is therefore an object of the present invention to provide an emergency unlocking device for such a brake capable of operating even in the absence of a source of fluid under brake activation pressure (hydraulic failure) and / or in the absence of electrical current (electrical failure).

  It is also an object of the present invention to provide such a device having high reliability.

  It is also an object of the present invention to offer such a device, the repeated implementation of which would not compromise the operation of the parking brake.

  These aims are achieved by an emergency unlocking device for the parking brake according to the present invention comprising means for pushing on a key for locking and / or locking the parking brake in the activated condition.

  Advantageously, the thrust takes place along the axis of translation of a key 30 forming the locking and / or locking means.

  Advantageously, the pushing means comprise a screw cooperating with a thread so that the rotation of this screw pushes the key towards a position corresponding to the deactivated condition of the parking brake. 35 The use of a screw makes it possible to generate, by a compact device, forces necessary for release, for example equal to 4000 N. The rotation in the opposite direction subsequently makes it possible to reactivate the parking brake when this is necessary. longed for.

  The present invention mainly relates to a disc parking brake comprising a piston for applying pads on the disc, means for supplying a fluid under sufficient pressure to be capable, on command, of applying the pads firmly on the disc, means for blocking the piston in a first condition in which the pads are firmly applied to the disc, characterized in that the blocking means comprise a key and an actuator for displacement on command of said key along an axis not parallel to the axis of the piston between a first position of the key in which it does not oppose the recoil of the piston along its axis and a second position of the key in which it ensures a blocking of the piston in the condition in which said piston firmly applies the pads on the disc and in that it comprises manual means of axial thrust along the axis not parallel to the axis of the piston for repo use the key in said first position to ensure emergency release of the brake.

  The present invention also relates to a brake characterized in that the axial thrust means comprise a thread cooperating with a tapping of the caliper or of a part made integral with the caliper, and a thrust part whose manual rotation in cooperation with said tapping is capable of pushing the key from said second position to said first position. The present invention also relates to a brake, characterized in that the thrust piece is a screw.

  The present invention also relates to a brake, characterized in that the screw is directly screwed into a thread formed in the caliper of the brake.

  The present invention also relates to a brake, characterized in that it comprises a sleeve secured to the caliper, the sleeve being provided with a thread in which said screw is screwed.

  The present invention also relates to a brake characterized in that the caliper comprises a thread and the sleeve a thread and characterized in that the sleeve is secured in translation with the caliper by screwing the sleeve into the thread of the 'stirrup.

  The present invention also relates to a brake, characterized in that the unlocking device comprises a seal.

  The present invention also relates to a brake, characterized in that it comprises means for retaining the thrust piece.

  The present invention also relates to such a brake, characterized in that the means for retaining the thrust piece comprise a circlip.

  The present invention also relates to such a brake, characterized in that the means for retaining the thrust piece comprise a flange bearing on the caliper or on a part secured to the caliper when the thrust piece is forcibly screwed in the thread.

  The present invention also relates to such a brake, characterized in that the means for retaining the thrust piece are formed by plastic deformation of an axially external zone of a thread for receiving the screw.

  The present invention seems to be better understood by means of the description below and the 45 appended figures given as nonlimiting examples and in which: - Figure 1 is a sectional view of an exemplary embodiment of a brake equipped with a device according to the present invention; - Figure 2 is an enlarged sectional view of the emergency unlocking device according to the present invention; - Figure 3 is a sectional view of an alternative embodiment of an unlocking device according to the present invention.

  In FIGS. 1 to 3, the same references have been used to designate the same elements.

  In Figure 1, there is shown an embodiment of the brake according to the present invention. This example corresponds to a floating caliper disc brake 1 also providing the main service brake function. In the example illustrated, a rear brake is shown, it being understood that the use of a parking brake according to the present invention on front wheels and / or of a parking brake separate from the main service brake does not is not beyond the scope of the present invention.

  The caliper 1 is provided with a blind bore 3 forming a hydraulic cylinder of a piston 5 provided with a device 7 for taking up brake shoe wear comprising, in known manner, a nut 9 and a screw 11 unscrewing relative to the nut 9 as the brake pads wear. However, it is understood that the implementation of the device 7 for taking up wear on brake pads having a nut and a screw reversed in position, does not depart from the scope of the present invention. A rear part 13 of the stirrup 1 comprises a housing of a key 15 for direct or indirect mechanical blocking. In the example shown, the blocking is carried out by means of the device 7 for compensating for the wear of the pads, of the piston 5 in a first condition in which the pads (not shown) are firmly applied to the disc (also not shown).

  By firm application is meant an application making it possible to immobilize vehicles, in particular on a slope. It is commonly considered that such an application corresponds to a force of 10,000 N to 20,000 N. In a second condition, the key 15 does not oppose the recoil of the piston 5. In the preferred example illustrated, the key 15 is mounted in translation along an axis Y perpendicular to the axis X of the hydraulic piston 5. The key 15 has a first support zone 17 for the rear face 19 of the nut 9 and a second support zone 21, offset along the Y axis relative to the zone 17 and having a forward extension, along the X axis, in the direction of the hydraulic piston 5 greater than the extension along the X axis, in this same direction, of zone 17.

  In the preferred embodiment illustrated, the nut 9 is substantially cylindrical with an axis X, the rear face 19 has two zones spaced along the axis Y capable of coming into contact with the key 15. The latter has a first first zone 17 followed by a first second zone 21 followed by a second first zone 17 followed by a second second zone 21.

  Advantageously, the zone or zones 21 have a gentle slope forming a ramp 45, the orientation of which facilitates the movement of the key 15 in possible contact with the rear face 19, according to arrow 23. In the example illustrated, the extension according to the X axis of the zones 21 increases from left to right.

  The brake according to the present invention comprises an actuator making it possible to move, on command, for example when the driver presses a key, a lever, a pedal or the like, located in the passenger compartment, the key 15 along the Y axis, in the direction of the arrow 23. This movement ensuring the parking brake lock can also be controlled by a computer, for example when the engine of the vehicle has been stopped and / or when the driver has left the vehicle. On the other hand, it is advantageous to use only hydraulic braking without mechanical blocking of the piston when stopping at a red light or when starting on a hill (Hill Holder in English terminology). In the preferred example illustrated, the actuation of the key 15 is hydraulic by means of a solenoid valve 25, of the closed-at-rest type connecting, on command 27, a pressure chamber 29 situated at a first axial end of the key 15 at the pressure prevailing in the cylinder 3. The valve 25 is arranged at the level of the hydraulic unit of the vehicle braking system or advantageously, at the level of the caliper 1.

  However, it is understood that the implementation of a parking brake comprising a valve 25 open at rest does not depart from the scope of the present invention.

  The activation of the parking brake according to the present invention will be explained below. The driver actuates the parking brake activation command, for example by pressing a button or a switch placed in the passenger compartment. Advantageously, a computer (not shown), for example the brake system computer, checks that the driver's instructions correspond to satisfactory safety conditions. For example, if the vehicle speed is greater than 5 km / h, the order to apply the parking brake is not directly executed, but the driver is warned of the anomaly by a light and / or audible signal. The computer detects the change in state of the parking brake control button and controls the supply of brake fluid under high pressure, for example between 107 Pa and 1.7 107 Pa in cylinder 3 from a pressure source not shown, such as a pneumatic brake booster (booster in English terminology) active controlled by an electric valve, a pump or an accumulator. Advantageously, use is made of a source of pressurized brake fluid already available in a modern vehicle such as ABS pumps or accumulators, ESP pumps or accumulators, EHB pumps or accumulators or others. The pressure difference between the high pressure of the brake fluid prevailing in the cylinder 3 and the atmospheric pressure prevailing in particular at the front face of the piston 5 ensures the advancement of the latter according to arrow 41, in the direction of the disc with clamping. pads on the disc ensuring the immobilization of the wheel. Insofar as at least 40 of a vehicle train is equipped with the brakes according to the present invention, the vehicle is immobilized. The play take-up device 7 also advances along the arrow 41, so as to avoid over-setting on the one hand by locking the screw 11 in rotation by applying the conical bearings 43 of the screw 11 and of the piston 5 and other share, to provide a space 45 between the rear face 19 of the nut 9 and the first contact zone 45 of the key 15. The thickness of the space 45 facilitates the movement of the key 15 according to arrow 23.

  The computer generates the valve 27 command to open the valve 25, putting the cylinder 3 into communication with the chamber 29. The pressure in the chamber 29 is at this time sufficient to move the key 15 according to arrow 23. The second bearing areas 21 of the key 15 are therefore opposite the rear face of the nut 9. A release of the pressure in the cylinder allows the piston to recede. The computer controls the pressure drop prevailing in the cylinder 3 causing a firm application of the rear faces 19 of the nut 9 on the second bearing zone 21 of the key 15. Simultaneously, the brake fluid flows from the chamber 29 to the cylinder 3 via the valve 25.

  The firm support ensures the translational locking of the key 15. As a result, the key 15 and the piston 5 (by means of the device 7) lock and / or mutually lock preventing the translation of the key despite a significant drop in the pressure in chamber 29. The parking brake is therefore applied in a perfectly stable condition even in the absence of hydraulic, electrical or other power.

  The computer then closes the valve 25 isolating the chamber 29 from the cylinder 3.

  It should be noted that the application of the high pressure in the cylinder 3 ensures an elastic deformation of the caliper 1, called the opening of the caliper, which stores considerable elastic energy ensuring parking braking. The amount of energy stored can be optimized by a particular design of the stirrup or the choice of materials implemented promoting this deformation when it is subjected to significant stresses imposed by the high pressure of the hydraulic fluid. For example, a stirrup made of cast iron, steel, composite material or a stirrup made of aluminum or cast iron with steel inserts is used. Likewise, this energy can be stored in elastic elements external to the caliper, for example to improve the resistance of the parking brake when cooling a brake applied at high temperature. As a variant, the braking system according to the present invention comprises means for measuring the clamping force of the parking brake and ensures an increase in this force by the cycles explained above when necessary, for example as a result of cooling of '' a brake applied hot after heavy service braking.

  It is understood that the present invention is not limited to the formation of a space 45 between the face 19 of the nut 9 and the key 15. It is perfectly possible without departing from the scope of the present invention to apply the parking brakes directly by moving the key 15 according to arrow 23.

  In the event of a failure of the hydraulic and / or electrical system, the emergency unlocking of the parking brake is carried out according to the present invention by ensuring manual pushing on the key 15, in the opposite direction to the arrow 23, so to bring back the zones 17 of the key 15 having a weak forward extension along the axis X of the hydraulic piston, facing the rear face 19 of the nut 9. When the parking brake is activated , the key 15 is locked in place by the force exerted by the device 7 of 45 backlash (and vice versa). To deactivate the parking brake, it is necessary to exert, along the Y axis of the key, a considerable force, for example equal to 4000 N. In the preferred example, the unlocking device 71, according to the invention, comprises a screw 73 cooperating with a thread 75 made in the stirrup (Figures 1 and 3) or in a sleeve 77 secured to the stirrup (Figure 2). Advantageously, the sleeve 77 is in turn secured to the stirrup by screwing. However, the implementation of other fixing methods such as for example bayonet is not beyond the scope of the present invention.

  In a rest condition, without emergency unlocking, the screw 73 is unscrewed (to the left of the figure) according to arrow 23 which saves space 79 sufficient for the operation of the key 15 towards the position ensuring application parking brake.

  If necessary, the emergency unlocking device 71 is provided with means ensuring the sealing of the brake fluid such as an O-ring 81 disposed in a groove trapped between the sleeve 71 and the caliper 1. 10 Advantageously, the device comprises means for blocking the screw to prevent, on the one hand, its unwanted application and / or, on the other hand, that it is not lost by a complete unscrewing beyond its position of rest. In the example illustrated in FIG. 2, the means for immobilizing the screw comprise a circlip 83 placed in a groove 15 formed in the sleeve 77. In the example illustrated in FIG. 3, the means for blocking the screw comprise a flange 85 preventing unwanted advancement of the screw 73 in the direction of the key 15. Advantageously, the screw 73 provided with the flange 85 is screwed slightly by force, during assembly, so as to avoid any untimely unscrewing of the screw. The flange 85 will be broken during screwing ensuring the emergency unlocking 20 by the axial force 23 ′ resulting from the rotation 87. As a variant, the flange is replaced by a pin.

  In a variant not shown during the assembly of the brake, a short screw 73 is screwed until its first end directed towards the key 15 is in place, 25 that is to say defines a space 79 sufficient to the operation of the key 15. The second end of the short screw 73, opposite the first end, is located inside the thread whose mouth can be slightly deformed to prevent the screw 73 from coming out accidentally.

  We will now explain the implementation of the emergency unlocking device according to the present invention. On a vehicle immobilized by a parking brake according to the present invention (parking brake activated), which one wishes to be able to move without being able to deactivate, by electrical and hydraulic control, the brake.

  After ensuring that the vehicle will not leave on its own, for example by putting chocks under the wheels in the case of a vehicle parked on a slope, the driver has grabbed a tool, typically a screwdriver or a key, comprising a tip adapted to the tip 89 of the screw 73 of the unlocking device 71. In the example illustrated, the screw 73 is provided with a hexagonal tip adapted to BTR type keys. However, it is understood that the implementation of other bits such as torque, 40 flat or Phillips screwdriver is not beyond the scope of the present invention. The driver rotates the screw until it pushes the key 15 back into the parking brake deactivation position. This operation is repeated with all the wheels braked by the parking brake according to the invention, typically the two rear wheels. Once the operations requiring the unlocking of the parking brake 45 have been carried out, the screws 73 are unscrewed to the initial position (FIGS. 1 and 3) or unscrewed and replaced (FIG. 2) so as to allow a new application of the parking brake according to the invention.

  It is understood that the present invention is not limited to the implementation of a screw 73 but also applies to the implementation of a nut, a ramp, a lever or any other tool ensuring the thrust on the key 15.

  The present invention is particularly applicable to the automotive industry.

  The parking brake according to the present invention mainly applies to the braking industry for a motor vehicle, in particular for a passenger vehicle. 10

Claims (11)

  1. Disc parking brake comprising a piston for applying pads on the disc, means for supplying a fluid under sufficient pressure to be capable, on command, of firmly applying the pads on the disc, means for blocking the piston in a first condition in which the pads are firmly applied to the disc, characterized in that the blocking means 10 comprise a key (15) and an actuator (25, 29, 31) for movement on command of said key (15) along an axis (Y) not parallel to the axis (X) of the piston (5) between a first position of the key (15) in which it does not oppose the recoil of the piston (5) according to its axis (X) and a second position of the key (15) in which it ensures a locking of the piston (5) in the condition in which said piston firmly applies the pads to the disc and in that it comprises means ( 71) axial thrust manuals (23 ') along the axis (Y) not parallel to the 'axis (X) of the piston (5) to push the key (15) in said first position to ensure emergency release of the brake.   2. Brake according to claim 1 characterized in that the means (71) of axial thrust comprise a thread (75) cooperating with a tapping of the caliper (1) or of a part (77) made integral with the caliper (1), and a thrust piece (73) whose manual rotation (87) in cooperation with said internal thread (75) is capable of pushing the key (15) from said second position towards said first position.   3. Brake according to claim 2 characterized in that the part (73) of thrust is a screw.   4. Brake according to claim 3 characterized in that the screw (73) is directly screwed into a thread (75) formed in the caliper (1) of the brake.   5. Brake according to claim 3 characterized in that it comprises a sleeve (77) 35 secured to the caliper (1) the sleeve being provided with a thread (75) into which is screwed said screw (73).   6. Brake according to claim 5 characterized in that the caliper comprises a thread (75) and the sleeve a thread and in that the sleeve (77) is secured in translation with the caliper by screwing the sleeve in the thread of the caliper.   7. Brake according to any one of the preceding claims, characterized in that the unlocking device comprises a seal (81). 45 8. Brake according to any one of the preceding claims, characterized in that it comprises means (83, 85) for retaining the part (73) of thrust.   9. Brake according to claim 8 characterized in that the means for retaining the part (73) of thrust comprise a circlip (83).   10. Brake according to claim 8 characterized in that the means for retaining the part 5 (73) of thrust comprise a flange bearing on the caliper (1) or on a part secured to the caliper (1) when the thrust piece (73) is forced into the thread (75).   11. Brake according to claims 3 and 8 characterized in that the means 10 for retaining the part (73) of thrust are formed by plastic deformation of an axially external zone of a thread (75) for receiving the screw ( 73).