Parking lock mechanism for a motor vehicle

Abstract

Parking lock mechanism for a motor vehicle, wherein the motor vehicle has a drive shaft (1) which is designed for mechanical power transmission to at least one drive wheel and wherein said drive shaft (1) has at least one locking region (2) and wherein a parking lock pawl (3) is provided for selectively forming a positive connection with said locking region (2), wherein the parking lock mechanism has a locking mode in which the parking lock pawl (3) is moved into a locking position and thereby forms a positive connection with the locking region (2), and furthermore the parking lock mechanism has a driving mode in which the parking lock pawl (3) is moved into a driving position in which it does not form a connection with the locking region (2), wherein the parking lock pawl (3) is pivotable about a pawl axis (4) from the locking position into the driving position and wherein a pawl spring device (5) is provided which pre-tensions the parking lock pawl (3) into the driving position and wherein a pawl actuating device is provided which has a pawl actuator (6) with a pawl actuator shaft (7) and a pawl cone (8), wherein the pawl cone (8) is movable along a cone axis (9) by means of the pawl actuator (6), wherein this cone axis (9) is aligned parallel to the pawl axis (4) and wherein the pawl cone (8) is movable along the cone axis (9) between a cone driving position and a cone locking position and wherein the parking lock pawl (3) is forced into the locking position by the pawl cone (8) in the cone locking position against the pretension of the pawl spring device (5), and wherein a locking cone lever (10) is provided for displacing the pawl cone (8) along the cone axis (9), wherein the locking cone lever (10) is freely rotatable by the pawl actuator shaft (7), and wherein a decoupling spring device with a decoupling spring is provided in the force transmission direction between the pawl actuator shaft (7) and the pawl cone (8), characterized in that the decoupling spring is designed as an actuator decoupling spring and is arranged between the locking pawl actuator shaft (7) and the locking cone lever (10) in the force transmission direction and is designed as a torsion spring and that the locking cone lever (10) is rotatably mounted on the pawl actuator shaft (7) and that the actuating force from the pawl actuator shaft (7) to the pawl lever (10) can be transmitted exclusively by means of the actuator decoupling spring.

Description

[0001] The invention relates to a parking lock mechanism in a motor vehicle, in particular in an electric vehicle.

[0002] In this context, a parking lock mechanism is understood to be a mechanism for positively locking a drive shaft, wherein the drive shaft, at least in the state in which the drive shaft is locked, is permanently coupled to at least one drive wheel of the motor vehicle or to a drive axle. A parking lock mechanism as such is known from the prior art, in particular from automatic transmissions. In such transmissions, the output shaft from the automatic transmission can usually be positively coupled to the transmission housing, in particular when the parking mode, so-called "P" mode (PNRD), is selected for the automatic transmission.

[0003] DE 10 2015 211 367 A1 discloses an automatic transmission of a vehicle with a central synchronization device and a method for operating an automatic transmission, wherein a parking lock function with a self-locking arrangement can be implemented in this transmission. DE 10 2017 203 346 A1 discloses a parking lock actuator for a motor vehicle transmission and a method for controlling the parking lock actuator. DE 10 2005 024 468 A1 discloses a parking lock. Reference is also made to JP 2005-207 570 A and KR 10 2014 0 129 901 A, which also show actuation mechanisms for parking locks.

[0004] Implementing the parking lock function typically requires a mechanically complex mechanism. It is an object of the invention to provide a simple parking lock mechanism. This object is achieved by a parking lock mechanism according to claim 1. Preferred developments of the invention are the subject of the dependent claims.

[0005] For the purposes of the invention, a parking lock mechanism for a motor vehicle is understood to be a device for positively locking a drive shaft, wherein this drive shaft is configured to transmit mechanical power to at least one drive wheel of the motor vehicle. This drive shaft is preferably selectively or preferably permanently connected to this at least one drive wheel in a torque-conducting manner. In particular, with such a configuration, the drive wheel is positively locked by means of the parking lock mechanism as soon as the parking lock is engaged.

[0006] Furthermore, the drive shaft to be locked has a locking region. The locking region is preferably designed as a locking gear, which is aligned concentrically with the drive shaft and which is further preferably connected thereto in a rotationally fixed manner or is preferably formed integrally therewith. Furthermore, the locking region is designed such that at least one parking pawl selectively engages it to form the positive connection. From a functional perspective, the drive shaft and thus the at least one drive gear are locked when the parking pawl engages the locking region of the drive shaft.In other words, the parking lock mechanism thus has at least two modes, the first of which can be regarded as "parking lock engaged", so-called locking mode, and the other as "parking lock disengaged", so-called driving mode, wherein in the first mode the drive wheel is positively blocked and in the second mode this is not the case, but rather in this mode the drive shaft is rotatable and the at least one drive wheel can be driven via the drive shaft.

[0007] Furthermore, the parking lock pawl is movable between at least two positions by means of the parking lock mechanism. In the locking mode, the parking lock pawl is moved into a locking position and, in this position, forms a positive connection with the locking area to block the drive shaft. Furthermore, the parking lock mechanism has a drive mode, in which the parking lock pawl is moved into a drive position in which it does not form a positive connection with the locking area. In particular, the drive shaft is rotatable in this mode to drive the motor vehicle.

[0008] Furthermore, the parking lock pawl is pivotable about a pawl axis to assume the locked or driving position. The parking lock mechanism has a pawl spring device that preloads the parking lock pawl into the driving position. In particular, in an unactuated state, the pawl spring device holds the parking lock pawl in the driving position. To change the position of the parking lock pawl, the parking lock mechanism has a pawl actuating device that includes a pawl actuator with a pawl actuator shaft and a pawl cone. The pawl cone is configured to apply, preferably indirectly or preferably directly, an actuating force to the parking lock pawl, under which the parking lock pawl is moved from the driving position to the locked position.In particular, to provide the actuating force to the parking lock pawl, the pawl cone is displaceable or movable along a cone axis by means of the pawl actuator. Further preferably, the pawl cone has a conical contour, at least in sections, with respect to the cone axis, and further preferably, the pawl cone contacts the parking lock pawl, in particular to move it from the driving position to the locking position.

[0009] This cone axis is aligned parallel to the pawl axis, and thus, in particular, the contour of the pawl cone, together with the movement of the pawl cone along the cone axis, allows the parking lock pawl to pivot about the pawl axis. The pawl cone is movable along the cone axis into at least two positions, one of which is considered the so-called cone locking position and the other the cone driving position. Furthermore, when the parking lock pawl is contacted by the pawl cone and the cone is in the cone locking position, it is moved into the locking position; in this situation, the parking lock pawl is forced into the locking position by the pawl cone against the spring force of the pawl spring device.If the pawl cone is in the cone driving position, the parking lock pawl is pushed into the driving position by the pawl spring device and the locking area of the drive shaft can rotate relative to the pawl.

[0010] To move the pawl cone along the cone axis, a locking cone lever is provided, which is directly or indirectly coupled to the pawl cone and which is further rotatable or pivotable by means of the pawl actuator shaft of the pawl actuator. The locking cone lever is freely rotatable by the pawl actuator shaft. For the purposes of the invention, a freely rotatable locking cone lever is understood to mean that, particularly when adjusting the pawl cone between the cone locking position and the cone travel position, only the forces applied to the locking cone lever via the pawl cone, as well as unavoidable bearing and inertia forces, act on the locking cone lever.Furthermore, "freely rotatable" preferably means that the pawl lever is freely rotatable at least between two end points. In particular, it is not necessary for the pawl lever to be able to perform a complete rotation (360° or more) for it to be understood as freely rotatable within the meaning of the invention. In particular, a freely movable or freely rotatable locking cone lever is not subject to any additional mechanical forces, such as those that can occur, in particular, when the locking cone lever is detented.

[0011] Such detents can be provided, in particular, to prioritize certain geometric positions of the locking cone lever. Such prioritization can be intended to reduce "play" in the parking lock mechanism or to specify a specific mechanical position of this mechanism in the event of a defective pawl actuator. In contrast, a freely rotatable locking cone lever offers the advantage of a simple parking lock mechanism and enables uniform and precise control of the pawl cone, since it can be moved without mechanically prioritized positions and thus uniformly along the cone axis.Furthermore, a parking lock mechanism is easy to sense because there is a simpler relationship between the movement of the pawl cone and applied operating forces than in a case in which (locking) forces that are not introduced by the pawl cone still act on the locking cone lever, and in particular this enables improved error monitoring of the proposed parking lock mechanism.

[0012] In a preferred embodiment, a decoupling spring device with a decoupling spring is provided between the pawl actuator shaft and the pawl cone, with respect to the force transmission between them. In particular, the decoupling spring device decouples the pawl actuator shaft from the pawl cone in at least one force transmission direction. Figuratively speaking, upon actuation of the parking lock mechanism, the pawl actuator shaft directly or indirectly transmits an actuating force to the decoupling spring device, and the decoupling spring device transmits this actuating force to the pawl cone.In a case in which the pawl cone is immobile, in particular because the parking pawl cannot or cannot yet engage the locking area, the actuating force from the pawl actuator shaft initially preloads the decoupling spring of the decoupling spring device without necessarily moving the pawl cone, which, however, exerts an actuating force on the parking pawl. If, due to changed geometric conditions, the parking pawl can engage the locking area at a different time and thus establish the positive connection between the parking pawl and the locking area, the pawl cone moves under the actuating force from the decoupling spring device into the cone locking position, thereby rotating the parking pawl into the locking position.In particular, by means of such a decoupling spring device, on the one hand, a secure engagement of the parking lock pawl into the locking area can be achieved and, on the other hand, the locking pawl actuator shaft can be decoupled from force shocks, such as can occur when the parking lock pawl collides with the locking area and does not yet establish a positive connection with it.

[0013] In a preferred embodiment of the parking lock mechanism with a decoupling spring device, the decoupling spring is arranged between the pawl actuator shaft and the locking cone lever in the force transmission direction. Further preferably, the decoupling spring is designed as a torsion spring or helical spring, and further preferably, such a decoupling spring is preloaded by a rotation of the pawl actuator shaft relative to the locking cone lever and can be understood as an actuator decoupling spring. Further preferably, force is transmitted from the pawl actuator shaft to the locking cone lever during scheduled operation, at least temporarily or preferably permanently and at least substantially, by means of the decoupling spring.Preferably, the locking cone lever is rotatably mounted on the pawl actuator shaft and mechanically coupled to it by means of the decoupling spring for transmitting actuating forces. In other words, an actuating force can be transmitted from the pawl actuator shaft to the locking cone lever by means of the decoupling spring. In particular, a rotatably mounted locking cone lever coupled with a decoupling spring is a particularly space-saving arrangement for providing a decoupling function between the pawl actuator shaft and the pawl cone as the actuating element for the parking lock pawl.

[0014] In an embodiment not according to the invention, the decoupling spring or preferably a further decoupling spring is arranged between the locking cone lever and the pawl cone in the force transmission direction. This decoupling spring or further decoupling spring arranged directly or indirectly between the locking cone lever and the pawl cone is preferably designed as a spiral spring or as a collection of several disc springs and can be understood as a lever decoupling spring. Further preferably, such a decoupling spring is preloaded relative to the pawl cone by a movement of the locking cone lever (driven by the pawl actuator shaft), in particular when the latter is blocked in its movement along the cone axis.Further preferably, force transmission from the locking cone lever to the pawl cone during scheduled operation takes place at least temporarily or preferably permanently, at least substantially, by means of this decoupling spring. Preferably, the locking cone lever is non-rotatably mounted on the pawl actuator shaft and is mechanically coupled to the pawl cone directly or indirectly by means of the decoupling spring for transmitting actuating forces to the pawl cone. In other words, an actuating force can be transmitted from the locking cone lever to the pawl cone by means of the decoupling spring. In particular, such a decoupling spring and thus an elastic coupling of the locking cone lever to the pawl cone constitute a particularly simple and reliable arrangement for providing a decoupling function.

[0015] In a preferred embodiment, the pawl cone is mounted on a pawl mandrel so as to be displaceable along the cone axis, with the pawl cone being forced onto the pawl mandrel by the lever decoupling spring into a final position on the pawl mandrel. Preferably, the lever decoupling spring is designed as a compression spring. Further preferably, the lever decoupling spring is thus arranged indirectly between the pawl cone lever and the pawl cone. Such an arrangement, in particular, enables particularly simple assembly, since the pawl mandrel with the pawl cone and lever decoupling spring mounted thereon can be mounted as an assembly, enabling particularly simple assembly of this assembly on the pawl cone lever.

[0016] In a preferred embodiment, the pawl actuator is designed as a self-locking actuator. For the purposes of the invention, a self-locking actuator is understood to mean, in particular, an actuator that maintains the position of the pawl actuator shaft without external power, in particular current and voltage, even when operating forces act on the pawl actuator shaft, in particular via the locking cone lever. In particular, such an embodiment of the invention enables a simple design of the parking lock mechanism, since no additional, particularly mechanical, locking mechanisms are required to maintain a specific position of the pawl actuator shaft.

[0017] In a preferred embodiment of the invention, the pawl actuator has a pawl sensor for determining the position of the pawl actuator shaft. Further preferably, the pawl sensor is designed as a rotation angle sensor. In particular, a pawl sensor allows the position of the pawl actuator shaft to be detected, thus making it possible to monitor the function of the pawl actuator.

[0018] In the following, individual features of the invention are explained in more detail with reference to the figures; combinations of features other than those shown are also possible in principle, as shown: Fig. 1: a perspective partial sectional view of the parking lock mechanism, Fig. 2: a top view of the parking lock mechanism.

[0019] In Fig. 1 shows a perspective partial sectional view of the parking lock mechanism; the drive shaft to be locked or positively locked with this mechanism is not shown in this figure.

[0020] The pawl actuator 6 is a rotary actuator having a pawl actuator shaft 7 for transmitting the actuating force to the pawl cone 8. The pawl actuator 6 is designed as a self-locking actuator. This means that when the pawl actuator 6 is deactivated, the position of the pawl actuator shaft 7 is maintained without the supply of energy (in particular current, voltage) from outside the pawl actuator 6, even if a force, in particular from the pawl cone 8, is exerted on the pawl actuator 6. Self-locking in the pawl actuator 6 can be achieved in particular via the friction conditions in the pawl actuator 6.

[0021] Furthermore, the pawl actuator 6 has a pawl sensor 13, with which the position of the pawl actuator shaft 7 can be detected and thus the operating state of the parking lock mechanism can be monitored. The pawl actuator 6 is shown in a sectional view. The locking cone lever 10 is arranged on the pawl actuator shaft 7 in a rotationally fixed manner and can pivot therewith in the pawl lever direction 19. A rotational movement of the pawl actuator shaft 7 thus leads to a movement of the locking cone lever 10. The pawl pin 12 is kinematically coupled to the locking cone lever 10. The pawl cone 8 is arranged on the pawl pin 12 and has a conical outer contour 14 at least in sections, with the cone axis 9 forming the axis of symmetry for this conical section 14.

[0022] The pawl cone 8 is movably mounted on the pawl mandrel 12 along the cone axis 9, i.e., in the cone movement direction 18, and is preloaded downwards into a position in the illustrated embodiment by means of the lever decoupling spring 11, which is designed as a compression spring. If the pawl mandrel 12 is moved by the pawl cone lever 10 in the cone movement direction 18, and no or only slight forces from the parking lock pawl 3 act on the pawl cone 8, the latter is moved along with the pawl mandrel 12. However, if direct engagement of the parking lock pawl is not possible, in particular because it cannot engage the locking area 2, in particular due to the rotational position of the locking area 2, the pawl cone lever 10 pushes the pawl mandrel 12 in the illustrated orientation from Fig. 1 downwards, the pawl cone 8 initially remains in its position (despite the movement of the pawl cone lever 10) and the lever decoupling spring 11 is tensioned. If the locking area 2 is then in a position relative to the pawl 3 such that the latter can engage in the locking area 2 to form the positive connection, the lever decoupling spring 11 presses the pawl cone 8 downwards (relative to the Fig. 1) and the parking lock pawl 3 is pivoted into the locking position shown.

[0023] In the presentation in Fig. 1, the pawl cone 8 is in its locking cone position, the parking lock pawl 3 rests against the cylindrical section 15 of the pawl cone 8 and is thus in its locking position, against the spring preload of the pawl spring device 5 (see Fig. 2), pivoted. To move the parking lock pawl 3, the pawl cone 8 rests on the abutment plate 16.

[0024] In Fig. 2, the parking lock pawl 3 is shown in the engaged state (locking position), i.e., the parking lock pawl 3 forms a positive connection with the locking area 2 of the drive shaft 1 and the drive shaft 1 is locked, or non-rotatable. The parking lock pawl 3 is movable in the pivoting direction 17 about the pawl axis 4, which is arranged axially parallel and radially spaced from the cone axis 8. The parking lock pawl 3 is preloaded into a driving position (not shown) by means of the pawl spring device 5. The pawl cone 8 is displaced along the cone axis 8 to engage the parking lock pawl 3 and is supported on the abutment plate 16 to apply an actuating force counter to the spring preload of the pawl spring device 5.

[0025] In other words, the described parking lock mechanism functions without additional detent, since the locking cone lever 10 is freely rotatable. A detent makes it possible to support and ensure a defined position status. The proposed parking lock mechanism, in particular, dispenses with such a detent. The invention proposes enabling the positioning of the parking lock mechanism by means of a self-locking pawl actuator, which cannot be moved from its actuated position (rotational position of the pawl actuator shaft) by forces applied via the pawl lever 10, or cannot be moved during scheduled operation. In the illustrated embodiment, the pawl actuator 6 is plugged directly onto the actuating mechanism.

[0026] The proposed invention makes it possible to reduce the number of additional components and interfaces of the parking lock mechanism. The position of the pawl actuator shaft 7 is monitored by a pawl sensor 13 on the pawl actuator 6. The tolerance chain of the components of the parking lock mechanism involved in motion transmission is thus ensured by a robust target position of this mechanism.

Claims

[1] Parking lock mechanism for a motor vehicle, wherein the motor vehicle has a drive shaft (1) which is designed for mechanical power transmission to at least one drive wheel and wherein said drive shaft (1) has at least one locking region (2) and wherein a parking lock pawl (3) is provided for selectively forming a positive connection with said locking region (2), wherein the parking lock mechanism has a locking mode in which the parking lock pawl (3) is moved into a locking position and thereby forms a positive connection with the locking region (2), and furthermore the parking lock mechanism has a driving mode in which the parking lock pawl (3) is moved into a driving position in which it does not form a connection with the locking region (2), wherein the parking lock pawl (3) is pivotable about a pawl axis (4) from the locking position into the driving position and wherein a pawl spring device (5) is provided which pre-tensions the parking lock pawl (3) into the driving position and wherein a pawl actuating device is provided which has a pawl actuator (6) with a pawl actuator shaft (7) and a pawl cone (8), wherein the pawl cone (8) is movable along a cone axis (9) by means of the pawl actuator (6), wherein this cone axis (9) is aligned parallel to the pawl axis (4) and wherein the pawl cone (8) is movable along the cone axis (9) between a cone driving position and a cone locking position and wherein the parking lock pawl (3) is forced into the locking position by the pawl cone (8) in the cone locking position against the pretension of the pawl spring device (5), and wherein a locking cone lever (10) is provided for displacing the pawl cone (8) along the cone axis (9), wherein the locking cone lever (10) is freely rotatable by the pawl actuator shaft (7), and wherein a decoupling spring device with a decoupling spring is provided in the force transmission direction between the pawl actuator shaft (7) and the pawl cone (8), characterized by , that the decoupling spring is designed as an actuator decoupling spring and is arranged between the locking pawl actuator shaft (7) and the locking cone lever (10) in the force transmission direction and is designed as a torsion spring and that the locking cone lever (10) is rotatably mounted on the pawl actuator shaft (7) and that the actuating force from the pawl actuator shaft (7) to the pawl lever (10) can be transmitted exclusively by means of the actuator decoupling spring. [2] Parking lock mechanism according to one of the preceding claims, characterized by that the pawl actuator (6) is designed as a self-locking actuator. [3] Parking lock mechanism according to one of the preceding claims, characterized by that the pawl actuator (6) has a pawl sensor (13) for determining the position of the pawl actuator shaft (7).

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