PCT/EP2006/069831 - 1 2005P18574WOIN Description Device for mechanically releasing a motor-actuated parking brake for a motor vehicle The invention relates to an additional assembly for mechanically releasing a motor-actuated parking brake for a motor vehicle, in particular an electromotively actuated parking brake for a motor vehicle. Motor-actuated parking brakes for motor vehicles have been established practice for a fairly long time in motor vehicle construction because they have considerable advantages, as compared with solutions customary hitherto, in which the parking brake has been actuated by means of a lever on the middle tunnel of the motor vehicle via cable pulls. They have the advantage, as compared with the purely mechanical solution, that no hand brake lever is required on the middle console, and that no long cable pulls have to be installed, which require complicated structural measures and, during maintenance, entail corresponding maintenance measures. Furthermore, electrically actuated parking brakes in motor vehicles have the advantage that they exert a uniform action on the brake independently of the effort expended by the operator. These electric or motor-actuated parking brakes have the disadvantage, however, that, in the event of a power failure in the on-board power supply of the motor vehicle, motor actuation for releasing the brake is no longer possible. On account of this, structural measures are required in order to make it possible to release the parking brake in an emergency. Conventionally, motor-actuated parking brakes in motor vehicles possess a step-up gear which converts PCT/EP2006/069831 - 2 2005P18574WOIN the rotational movement of a drive motor into a translational movement for actuating the assigned brake cables. Known devices for mechanically releasing a motor-actuated motor vehicle parking brake therefore provide, for example, for the provision of a purchasing point for an additional tool in the region of a drive mechanism of the parking brake, said drive mechanism executing rotational movements. In an emergency, the parking brake can be released at this point by means of an inner hexagon by external action via the driver of the motor vehicle by means of a special tool placed there. More convenient measures provide for the engagement of a flexural shaft at a suitable point and for having the possibility of transferring a rotational movement to the drive mechanism of the parking brake via this flexural shaft. Measures which are mechanically less complicated or at least cause greater stresses provide, with a parking brake applied and the brake cables tensioned, for releasing the brake pull assembly mechanically. This takes place, for example, by means of a pawl mechanism which can be released via a pull. By means of this trigger device, the brake cables or one of the brake cables can be abruptly relaxed mechanically. The spring force stored in the brake then leads to the release of the parking brake in an emergency. An electric parking brake for a motor vehicle is known from European patent specification EP 0710595 Bl. In this electric parking brake, threaded rods or threaded sleeves are set in rotation and, by translation caused by this rotational movement, move fastenings of the brake cables. The mechanical actuation of the parking brake can thus take place via an electric motor. In one direction of rotation of the 3 motor, the parking brake is locked, and in the other direction of rotation it is released. In this parking brake, a mechanism for the abrupt relaxation of the brake cable is provided for emergency use. For this purpose, for example, a guide sleeve is attached to the 5 housing of the actuating mechanism for the brake. It holds a brake cable under tension and can be displaced by means of a pull. On its guide along the path which it covers as a result of the actuation of the pull, it can be released and slide into the interior of the housing. As a result, the brake cable is abruptly relaxed, and the brake is released under the spring action of the brakes. 10 This release mechanism, disclosed in the prior art, for an electric parking brake has the disadvantage, however, that this abrupt release of the brake cables which are under tension entails high mechanical stresses and, after the servicing of the on-board power supply of the motor vehicle, necessitates complicated mechanical measures in order to is make the electric parking brake and the mechanical parts of the parking brake which are connected to it operable again. In this case, the parking cable has to be notched in again by means of a calibrating run. Further devices for mechanically releasing motor-actuated motor vehicle parking 20 brakes are not known. Object of the Invention It is the object of the present invention to substantially overcome or ameliorate one or more of the disadvantages of the prior art. 25 Summary of the Invention The present invention provides a device for mechanically releasing a motor actuated parking brake for a motor vehicle, having: a drive shaft for releasing the parking brake in a first direction of rotation; a cage which surrounds at least part of the drive 30 shaft; a drive mechanism between the cage and the drive shaft, which drive mechanism is configured such that a relative movement of the drive shaft and of the cage with respect to one another in at least one essentially axial direction of the drive shaft gives rise to a rotation of the drive shaft in the first direction of rotation, the cage being arranged axially displaceably in a housing; and first means are present in order to prevent a rotational 35 movement of the cage in the housing.
4 Particularly advantageously, in a device for mechanically releasing a motor actuated motor vehicle parking brake according to the invention, a drive shaft is set by pull or pressure action in rotational movements which can then be used directly in order 5 to drive a step-up gear present for the motor actuation of the parking brake. Thus, the mechanical stresses in the region of the brake cables are minimized, and the problem that no abrupt stresses during the release of the parking brake in an emergency should occur is solved particularly advantageously in technical terms. The mechanical stresses in the region of the brake cables can therefore be kept low, thus leading, overall, to a higher 1o reliability of the parking brake system. Advantageously, in a development of the invention, a relative movement between a housing or cage of a drive shaft and the drive shaft is utilized in order to set the drive shaft in rotational movements. In this case, advantageously, the cage is obstructed in its is rotation, for example by means of a square fit, or by means of another type of mechanical solution, for example an oval fit, which prevents a rotation of the cage, while, if appropriate, allowing a simultaneous axial displacement of the cage of the shaft.
PCT/EP2006/069831 - 5 2005P18574WOIN Advantageously, in a development of the invention, the drive mechanism which converts a relative movement between a cage of the drive shaft and the drive shaft into a rotational movement is constructed such that two profiles constructed complementarily to one another cooperate, the first profile being arranged on the cage and the second profile being arranged on the drive shaft. Particularly advantageously, by virtue of this design, in accordance with mechanical strength requirements of the shaft and of the cage, either grooves or tenons may be used as profiles and be formed at a suitable point. Particularly advantageously, a development of the device according to the invention for mechanical release has second means which fix the first and the second profile in the direction of rotation with respect to the cage, so that they transmit force in the first direction of rotation. A releasable connection is thus provided which, when the motor actuated parking brake is operated in an emergency, allows an actuation of the mechanism solely in the reverse direction of rotation opposite to the parking direction. This advantageously ensures, during the resetting of the release mechanism, that no force is transmitted from the shaft to the cage or the housing. Particularly advantageously, in the device according to the invention, in a development the profiles for force transmission are configured such that, in the event of an axial displacement of the cage and of the drive shaft in relation to one another, an action of force against an oblique flank occurs, as a consequence of which a resultant torque is generated in the direction of rotation of the drive shaft.
PCT/EP2006/069831 - 6 2005P18574WOIN Such an action may be achieved, for example, by means of a continuous annular slot, continuous drive helics or a cardioid curve which is moved toward stationary tenons. Advantageously, in this respect, care must be taken to ensure that the pitch of the oblique flank is selected such that the effort and the generated torque are in suitable relation to one another, so that the parking brake can be released by a person with tolerable effort. Advantageously, in a development of the device according to the invention for releasing the parking brake, the second means are configured as a freewheel, because freewheels constitute common mechanical solutions, such as are known, for example, from bicycles, in order to transmit drive torques in only one direction of rotation, while at the same time they make a reliable mechanical connection, thus ensuring high long-term reliability. Advantageously, in development of the device according to the invention for mechanically releasing the parking brake, the second means are implemented in the form of an engaging wheel which can be latched into an end-face internal toothing of the cage and which has the first profile. Advantageously, in a development of the device according to the invention, between the cage and the housing of the device for mechanically releasing the parking brake a spring is arranged, which, in the event of a relative movement of the cage and of the drive shaft with respect to one another, is prestressed and exerts a counter force which can be used in order to reset the device.
PCT/EP2006/069831 - 7 2005P18574WOIN The spring action can also ensure that the cage and the housing are held with respect to one another in a first position in which they remain in the state of rest. Advantageously, a development of the device according to the invention provides for the profiles to be configured such that the profiles do not cooperate in the first position. In this case, it is particularly advantageously possible to couple the device of the invention non-positively to the drive mechanism, that is to say the actuating mechanism of the parking brake, in which case, in the first position, even with regard to electrical or other mechanical actuation of the parking brake, the device according to the invention is co-actuated and, since it is precisely not coupled, is freely movable, so that no mechanical couplings are required in this case. Advantageously, a development of the device according to the invention provides for the relative movement between the cage and the drive shaft of the device to be generated by a pull, because pulls can be produced cost-effectively and constitute reliable solutions in the sector of motor vehicle construction. Advantageously, a development of the device according to the invention provides for the engaging wheel to be axially displaceable, the axial movement play being such that the first and the second toothing can be released in the axial direction. This advantageously affords a mechanically cost-effective solution for coupling the profiles and consequently the rotational movement which is necessary for driving and for releasing the electric parking brake in an emergency.
PCT/EP2006/069831 - 8 2005P18574WOIN In a development of the device according to the invention, the axial displaceability of the engaging wheel is advantageously made possible by an axial securing ring which limits the axial displacement with respect to the cage. Securing rings are mechanically simple, constitute cost-effective standard solutions and afford advantages with regard to the mounting of the device. In a development of the device according to the invention, particularly advantageously, the drive shaft of the device is at the same time the drive shaft of a motor-operated parking brake, so that no additional coupling component for coupling the device to the parking brake is required. In the production of the parking brake, advantageously, it is necessary merely to construct a longer shaft which has the additional components required for the drive shaft of the device. As a result, at the same time, a simple mechanical coupling of the device to the drive of the electric parking brake is provided, and also a cost-effective method for manufacturing this device. The invention is explained in more detail below with reference to figures. Fig. 1 shows a motor-actuated parking brake for a motor vehicle according to the prior art. Figures 2 and 3 show a front view and a side view of an embodiment of the mechanical device for PCT/EP2006/069831 - 9 2005P18574WOIN releasing a motor-actuated motor vehicle parking brake according to the invention. Fig. 4 shows a view of a detail of the cage of an embodiment of the invention. Fig. 5 shows an exploded view of a detail of the device according to the invention. Fig. 6 shows an enlarged view of the engaging wheel and of the cage of the device according to the invention. Fig. 7 shows a sectional view along the mid-axis of the drive shaft of an embodiment of the invention. Fig. 8 shows an enlarged sectional view in the region of the end face of the cage of a device according to an embodiment of the invention. Fig. 1 shows an actuating unit 11 for an electrically actuated parking brake of a motor vehicle according to the prior art. In the brake according to the prior art, there is in the actuating unit 11 a drive motor 2 which is activated via supply lines 9. The drive motor 2 drives via a drive shaft 8 a drive pinion 1 of a step-up gear intermeshed with a gear pinion 3 which acts on threaded rods 4 and 6, the threads of which are contra directional, and sets these threaded rods in rotation during rotations of the motor. The rotational movement of the threaded rods when the motor is actuated leads, depending on the direction of rotation, to the route of the brake cables 5 and 7 in or out of the pull directions 51 and 71 indicated by arrows. In one direction of rotation, the threaded rods 4 and 6 move the PCT/EP2006/069831 - 10 2005P18574WOIN fastenings of the brake pull assemblies 5 and 7 such that these move inward into the housing of the actuating unit 11 and tighten the brake pull assemblies. In the other direction, they release the brake pull assemblies again. A mechanical release device for releasing the motor-actuated parking brake according to the prior art provides, in the region of the brake pull assembly 5, for the latter to be releasable by means of a displacement of the fastening and the tensioned brake cable to be released abruptly, with the result that the threaded rods 4 and 6, which are freely displaceable axially in the gear pinion 3, move to the right and thus in the direction of the arrow 71 and thereby also release the brake cable 7. A resetting force is in this case generated by the brake springs of the parking brake. Fig. 2 shows a front view of an embodiment of the device according to the invention for releasing a motor-actuated parking brake 10. The device has a housing 20, a cage 30, a securing ring 40, a drive pinion 60 and a drive shaft 70. Between the housing 20 and the cage 30, a spring 50 is arranged such that it gives rise, during an axial displacement of the cage 30, to a force driving back in the direction of the initial position shown in fig. 2. Fig. 3 shows the embodiment, illustrated in fig. 2, of the device according to the invention in a side view. It should be mentioned in this respect that identically acting components of embodiments of the device according to the invention are designated by the same reference symbols throughout all the figures. The drive shaft 70 of the embodiment of the device according to the invention may, PCT/EP2006/069831 - 11 2005P18574WOIN for example, be coupled directly to the drive shaft 8 of the device according to the prior art or form a mechanical unit with this drive shaft, so that the device according to the invention can generate a rotational movement directly on the motor shaft or another drive shaft of the device according to the prior art, which is shown in fig. 1. As can also be seen from fig. 3, the cage 30 has attached to it a pull cable 80, by means of which the cage can be pulled to the right in fig. 3, as seen from the front. This movement is necessary in the example shown here, if, in an emergency, the motor actuation of the parking brake fails and a mechanical release of this parking brake is required. The use of a pull cable 80 for generating the movement constitutes a simple structural measure. Other actuating means, such as rods or hydraulic or pneumatic cylinders, may also be envisaged. Fig. 4 shows a detail of the embodiment of the device for mechanically releasing a motor-operated parking brake for a motor vehicle according to an embodiment of the invention. The cage 30 and the pull cable 80 can be seen here in detail, and said pull cable may be designed, for example, as a Bowden pull cable in order to bring about an axial movement of the cage. The illustration in fig. 4 shows clearly a square as a locking component 35 which secures the cage 30 in the housing 20 against rotation, so that a torque can be generated on the drive shaft 70 by means of the mechanical operating parts of the device according to the invention. Fig. 5 shows clearly an exploded view of building-up parts of an embodiment of the device according to the PCT/EP2006/069831 - 12 2005P18574WOIN invention. In particular, what can be seen here are the drive shaft 70, the pinion 60, a thinned part of the shaft 65, which has no first profile in a first portion, and a part of the drive shaft which has a first profile 75. Furthermore, the securing ring 40, the engaging wheel 90 and the cage 30 and pull cable 80 can be seen. Running tenons 63 can also be seen clearly in the region of the engaging wheel 90. The running tenons 63 of the engaging wheel 90 cooperate with the tenon running surface 65 or the drive running surface 75 of the drive shaft 70 when the device according to an embodiment of the invention is actuated in order to trigger the mechanically actuated release of the electrically actuated parking brake. In the illustration in fig. 5, the profile on the shaft is configured such that it encircles the latter helically, and the profile parts on the engaging wheel are configured as tenons which cooperate with the profile on the drive shaft 70. However, it is clear to a person skilled in this art that the reverse arrangement with respect to the engaging wheel and the shaft is likewise possible, that is to say tenons could be present on the shaft, and a corresponding spiral or running worm could be arranged on the engaging wheel, and the same action would be achieved. Fig. 6 shows an enlarged view of the cage 30 and of the engaging wheel 90. What can be seen clearly in the region of the cage 30, on its end face, is an axial internal toothing 38 and, in the region of the engaging wheel 90, an end-face toothing 95. The toothing pairing 95, 38 is preferably designed as a helical toothing. The helical toothing allows improved force transmission in the direction of release of the parking brake. In the opposite direction, when PCT/EP2006/069831 - 13 2005P18574WOIN the mechanism for releasing the brake is being reset into its state of rest, said helical toothing is beneficial for a rapid separation of the intermeshing and likewise prevents force transmission in this direction. Parts of the first profile in the form of drive tenons on the engaging wheel, which are designated by 63, can also be seen clearly in the illustration. The engaging wheel 90 is mounted inside the cage 30, the securing ring 40 being removed during mounting. Said engaging wheel is subsequently inserted through the orifice in the region of the end face of the cage 30, after which the securing ring 40 is attached to the engaging wheel 90. This securing ring has an axial position which allows the engaging wheel 90 to be moved axially with respect to the end face or the shaft of the drive axis, so that at least a release of the toothing 95 and of the toothing 38 is possible. Fig. 7 shows a sectional view of an embodiment of the device according to the invention in the longitudinal direction. What can be seen are the drive worm with a running surface 75, the pull cable 80, the running tenons 63, the running surface 65, the engaging wheel 90 and the drive shaft 70. It can be seen particularly clearly from fig. 7 that the toothing is not latched, and that the tenons 63 run in the region of a running surface which allows no drive and where no torque would be transmitted between the shaft and the cage, even if there were a coupling of the end-face toothing of the cage to the toothing of the engaging wheel. As can be seen, for example, from fig. 2, the drive shaft 70 is fixed axially in the region of the drive pinion 60. If, then, to describe the function, the cage 30 is pulled rearward, that is to say to the left in fig. 6, via a pull in the region of the pull cable 80, then, first, the PCT/EP2006/069831 - 14 2005P18574WOIN end-face toothing of the cage 30, said toothing being designated by 38, and the end-face toothing 95 of the engaging wheel 90 are brought into engagement with one another, since the cage moves in the direction of the engaging wheel and therefore the teeth come into engagement. The result of exerting a further pull via the pull cable 80 is that the running tenons 63 are pressed against the drive flank 72 of the drive worm on the drive shaft 70 and therefore couple the toothings 95 and 38 firmly to one another, because they are pressed together via the drive shaft 70 in cooperation with the drive flank 72 and the running tenons 63. With respect to the tenons, the inclined drive flanks 72 of the drive worm constitute an inclined plane and give rise transversely to the drive shaft to a force resulting from the pull in the direction of the cable 80 and setting the drive shaft in rotation when the pull is sufficient. Since the cage is prevented from a rotational movement, since it is secured in the housing by the square or locking component 35 which could also be designed, for example, as an oval or could be implemented by guide pins or the like which engage into grooves in the housing 20, only the drive shaft 70 can be set in rotation as a reaction to the transverse force caused by the pull, since the transverse force, by acting on the flank of the drive worm 75, has the effect of a torque on the drive shaft 70. That is to say, as a result of a further translational movement of the cage 30 to the left in fig. 7 in the direction of the pull cable 80, the running tenons 63 run along the worm of the drive shaft and set the drive shaft in rotation along their path by means of the transmitted pull. In this case, care must be taken to ensure that friction between the running tenons and the drive shaft in the region of the worm is appropriately taken into account, and that the pitch is selected such that the force exerted by the pull cable 80 PCT/EP2006/069831 - 15 2005P18574WOIN and the required number of revolutions for releasing the parking brake are suitably dimensioned and coordinated with one another. Suitable dimensioning may also mean that the cage is of longer configuration, and the length of the profile covered is prolonged in the region of the translational movement, so that the exertion of lower force or a higher number of revolutions of the shaft can be implemented. At the same time, account must be taken of the fact that, as likewise illustrated in fig. 3, the spring 50 is prestressed with respect to the housing 20 as a result of the translational movement of the cage 30. If the entire drive profile, here a drive worm, present on the shaft has been covered by the running tenons, for example, a stop is reached, and the operator releases the cage again, in that, for example, he lets go of the pull or releases the notch or the like. The cage is pressed to the right with respect to fig. 7 by the spring, which then again means that the running tenons of the engaging wheel 90 butt against the worm profile on the drive shaft 75, and in connection with this, on account of the axial displaceability of the engaging wheel in the region of the end face of the cage, the toothings 95 and 38 are uncoupled due to the pressure on the running tenons, and when the cage slides back to the right in fig. 7 the engaging wheel 90 alone rotates, without a torque being transmitted to the cage from the shaft. Fig. 8 shows an enlarged example of a sectional view of an embodiment according to the invention. Illustrated are the cage 30, the tenon running surface 65, the engaging wheel toothing 95, the cage end face 33 and the securing ring 40 and positions 110. the distance between the PCT/EP2006/069831 - 16 2005P18574WOIN positions 100 and 110 is dimensioned such that the end-face toothing of the engaging wheel 95 and the end-face toothing of the cage 38 are not in engagement during the maximum axial displacement, indicated by these positions, of the engaging wheel with respect to the cage, so that intermeshing can be decoupled when the device, that is to say the cage, is returned into its initial position again by the spring 50 after release, that is to say the release of the electrically actuated mechanical parking brake. To a person skilled in this art it is clear that the end-face toothing of the cage 38 and of the engaging wheel 95 may be dispensed with if, instead, a freewheel, not shown, is used, which is known from the bicycle sector and which allows only the transmission of the torque between shaft and cage in a direction which in this case must be the drive direction for releasing the motor-actuated parking brake. A freewheel of this type, although costly, has the advantage that, in the case of frequent actuation, it is not exposed to such high wear as the spur toothing solution. In this respect, it should be noted that the invention has in this case been described merely in the form of an exemplary embodiment, but that modifications are possible within the framework of the principles specified. For example, during translational movement, rotation may be generated via a different curve than a helix of constant pitch, for example by means of a cardioid curve. The profiles may have other pitches or be smaller, or they may be arranged inversely or otherwise. It is likewise conceivable that the cage is not displaceable, although, in practice, this should constitute the most beneficial principle, but, instead, the drive shaft 70 is coupled to a shaft, PCT/EP2006/069831 - 17 2005P18574WOIN to be driven, of the motor-actuated parking brake, such that the shaft of the device 70 is axially displaceable, and, instead of the cage, the drive shaft is made axially displaceable. As a result, by means of a configuration of the mechanical arrangement, albeit technically more complicated, the same effect is achieved, without the principle of the invention being impaired. In this case, however, the coupling solution between the parking brake of the motor vehicle and the device for mechanically releasing the parking brake would be more complicated. For example, the rotational movement would then have to be transmitted via a hollow shaft which allows an axial displacement of the drive shaft in it. The relative movement could be generated, for example, via a push rod which exerts pressure at the free end on the drive shaft.