Device for preventing unintentional activation of a parking lock function in a transmission

Abstract

Device for preventing unintentional activation of a parking lock function in a 2-speed transmission, wherein gearshift positions of the transmission and its parking lock function can be accessed via a shift drum (2), wherein a mechanically active device (18) is provided which blocks the access to a parking lock position of the shift drum (2) when the shift drum (2) rotates in a first direction of rotation (8), then releases the blocking when the shift drum (2) rotates in a second direction of rotation (9) opposite to the first direction of rotation (8) and then allows the access to the parking lock position in the first direction of rotation (8) opposite to the second direction of rotation (9).

Description

[0001] The invention relates to a device for preventing unintentional activation of a parking lock function in a two-speed transmission. Such a transmission forms, for example, part of an electrically driven axle of a motor vehicle, in particular a passenger car.

[0002] In transmissions, the parking lock function is typically achieved through the interaction of a parking lock gear and a locking pin. When the vehicle is stationary, the parking lock can be engaged, with the pin engaging the parking lock gear and locking the transmission.

[0003] The object of the present invention is to provide a device for preventing unintentional activation of a parking lock function in a 2-speed transmission, which does not require a separate parking lock gear.

[0004] The problem is solved by a device having the features of patent claim 1.

[0005] In this 2-speed transmission, the gearshift positions and its parking lock function can be accessed via a shift drum. A mechanically active device is provided that blocks the shift drum from reaching a parking lock position when the shift drum rotates in a first direction. It then releases the block when the shift drum rotates in a second direction opposite to the first direction. It then allows the parking lock position to be reached in the first direction opposite to the second direction.

[0006] This feature prevents the shift drum from accidentally engaging the parking lock position due to incorrect actuator control when a clutch in the two-speed transmission is engaged, particularly when a shift clutch is engaged to engage first gear. This prevents the transmission from locking while driving. The position of the transmission clutches is controlled, for example, via a correspondingly shaped gate on the shift drum.

[0007] Thus, a mechanical device is proposed which, depending on the direction of movement or rotation of the shift drum, initially prevents the shift drum from reaching a specific position by means of a blockage, in particular a positive-locking blockage, which can be activated by overtraveling a specific position. The shift drum is released to reach the initially blocked position by first retracting the shift drum from the blocked position over a specific distance or angle, thereby releasing the parking lock function by overtraveling.

[0008] To shift the two gears of the transmission, the clutch and a shift dog are provided, with the latter also being able to have a freewheel associated with it. In particular, the clutch is engaged and the shift dog is open in second gear, while in first gear, when the vehicle is towing and the transmission is in neutral, both the clutch and the shift dog are in their open positions. When driving in first gear, where overrun mode must also be taken into account, the clutch is in its open position and the shift dog is in its closed position. If the shift drum is rotated further in order to move it from the second gear position via the first gear position into the parking lock position, a shifting state is created in which both the clutch and the shift dog are engaged.For safety reasons, this parking lock position of the shift drum must never be inadvertently reached, especially by further rotating the shift drum beyond first gear toward the parking lock position. This is prevented by a mechanically effective device included in the system.

[0009] According to a preferred embodiment, the device has two base parts that can move relative to one another, furthermore a flexible first stop mounted in one, the first base part, and second and third stops mounted in the other, the second base part. The second stop is mounted in the second base part so that it can be moved to a limited extent in the relative directions of movement of the base parts. The third stop is displaceable perpendicular to the relative directions of movement of the base parts in the direction of the first base part and in the opposite direction. During relative movement of the two base parts, the second stop is moved to a limited extent by means of the first stop, and the third stop extends in the direction of the first base part.This is achieved in such a way that, after a limited movement of the second stop toward the third stop, upon further relative movement of the two base parts, the second stop can be overridden by the first stop, but the third stop cannot be overridden by the first stop. Because the third stop is extended and cannot be overridden by the first stop, the two base parts are prevented from moving so far relative to each other, in particular from rotating so far relative to each other, that the shift drum is rotated into the parking lock position.

[0010] In this context, it is considered particularly advantageous if the second stop has a projection that extends the third stop toward the first base part when the second stop is moved toward the third stop. This projection tapers conically, particularly toward the third stop, so that as the second stop and the third stop approach each other, the third stop is continuously extended.

[0011] It is further considered advantageous if spring means are provided for preloading the third stop into its retracted position. Thus, the third stop is only extended when the second stop or the projection of the second stop acts on the third stop. If the action of the second stop on the third stop is reversed, the spring means cause the third stop to retract in accordance with the second stop, which no longer acts on the third stop to the same extent.

[0012] From the aspect of the preferred embodiment of the device, it is considered to be particularly expedient if, at the time when the first stop is located between the second stop and the third stop, when the first stop and the second stop move towards each other, the second stop is pushed back to a limited extent and the second stop releases the third stop, whereby the third stop retracts.

[0013] In particular, when the second stop is pushed back and the third stop is retracted, the third stop can be overrun by means of the first stop to reach the parking lock position of the shift drum.

[0014] Starting from the parking lock position, it is easy to return to the gearshift positions, especially the first gear. To do so, all that is required is to move the shift drum from the parking lock position and over the retracted third stop and the second stop using the first stop. This allows a gearshift position, especially the first gear position, to be reached.

[0015] It is considered particularly advantageous if the first base part is a component of the shift drum or is connected to the shift drum in a rotationally fixed manner, and the second base part is stationary. Thus, the first stop is a component of the shift drum or is connected to the shift drum in a rotationally fixed manner.

[0016] The flexible first stop, mounted in the first base part, is designed, in particular, as a spring pin. This pin is straight, particularly in its rest position, i.e., when the spring is not deflected, whereas the spring pin or spring is deflected in a curved manner when it yields.

[0017] Further features of the invention emerge from the subclaims, the attached drawing and the description of the preferred embodiment shown in the drawing, without being limited thereto.

[0018] It shows: Fig. 1 in a spatial representation of a shift drum forming part of the device according to the invention for use in a 2-speed transmission, Fig. 2 a diagram to illustrate the developed gate arrangements of the shift drum for switching the transmission gears and the parking lock function, Fig. 3 shows a schematic representation of the mechanically active device provided in the device for limiting the shift drum travel, illustrated in an initial position of the shift drum, which corresponds to the engaged first gear, Fig. 4 to 8 functional sequences for approaching the parking lock position of the shift drum, starting from the state according to Fig. 3, Fig. 9 starting from the parking lock position of the shift drum according to Fig. 8, the initial position of the shift drum according to Fig. 3, thus with first gear engaged.

[0019] Fig. 1 shows a shift drum 2 rotatable about an axis 1 for the purpose of actuating a 2-speed transmission as part of an electrically driven axle of a motor vehicle, in particular a passenger car. This shift drum 2 has two gates 3, 4, with a switching pin 5 or 6 engaging in the associated gate 3 or 4. The switching pin 5 serves to actuate a clutch, for example a frictionally engaged clutch. The switching pin 6 serves to actuate another clutch, which is designed as a shift claw. The frictionally engaged clutch serves as the shifting element for the second transmission gear. The shift claw, which interacts with a freewheel, serves as the shifting element for the first transmission gear. The freewheel is only active in one direction of rotation.

[0020] Fig. Figure 2 shows the switching states of the frictionally engaged clutch and shift dog. In second gear, the frictionally engaged clutch is in its closed position and the shift dog is in its open position. In first gear during traction and with the transmission in neutral, both the frictionally engaged clutch and the shift dog are in their open positions. In first gear, thus also taking into account overrun, the frictionally engaged clutch is in its open position and the shift dog is in its closed position. When the parking lock is engaged, i.e. when the shift drum is in the parking lock position, both the frictionally engaged clutch and the shift dog are in their closed position.This parking lock position of the shift drum 2 must under no circumstances be activated accidentally, especially when the vehicle is moving, because in this position the entire transmission is blocked. With this in mind, the device for limiting the travel of the shift drum 2, starting from first gear to the parking lock position of the shift drum 2, is described below.

[0021] A highly simplified illustration is shown in Fig. 3 shows a portion of the shift drum 2, wherein the rotational movement of the shift drum 2 is illustrated by a linear movement according to arrow 8. A stationary part 7, for example a housing part, is arranged opposite the shift drum 2. The shift drum 2 can thus be moved relative to the stationary part 7 in the direction of arrow 8 or opposite to the direction of arrow 9.

[0022] A flexible first stop 10 is mounted in the shift drum 2. This is designed as a spring pin having a coil spring 11 mounted in the shift drum 2 and a stop ball 12 connected to it. The coil spring 11 is directed towards the stationary part 7, and the stop ball 12 connected to the coil spring 11 is arranged at a short distance from the stationary part 7. A second stop 13 and a third stop 14 are mounted in the stationary part 7. The second stop 13 penetrates a guide slot 15 in the stationary part 7, with this guide slot 15 being oriented in the direction of the arrows 8, 9. Thus, the second stop 13 can be moved to a limited extent in the direction of the arrows 8, 9 due to the length of the guide slot 15. The third stop 14 is mounted in the stationary part 7 so that it can move exclusively perpendicular to the direction of the arrows 8, 9, towards or away from the switching drum 2.The second stop 13 is provided with a projection 16 which, starting from that region of the second stop 13 which is mounted in the stationary part 7, tapers conically towards the third stop 14. The surface 17 of the projection 16 facing the stationary part 7 therefore does not run parallel to the stationary part 7. Not shown are spring means which act on the third stop 14 in such a way that the third stop 14 is pressed against the surface 17 of the projection 16. - The spring means described so far, in . Fig. The device 18 shown in Figure 3 serves to limit the travel of the shift drum 2 when the transmission is to be transferred to its parking lock function.

[0023] Fig. Figure 3 shows that, when the first gear is engaged, the first stop 10 is arranged on the side of the second stop 13 facing away from the third stop 14. In the position shown, the second stop 13 and the third stop 14 do not extend over the distance 19 between the shift drum 2 and the stationary part 7, but only over a portion of this distance. If the mechanically active device 18 is to be activated to achieve the parking lock function of the transmission, the shift drum 2 is rotated from the shift position of the first gear toward the parking lock position of the shift drum 2, whereby, with reference to the drawing shown, the first stop 10 comes against the second stop 13 and advances it to the end of the guide slot 15 in the direction of the third stop. The inclined surface 17 causes the third stop 14 to be pushed out until it contacts the shift drum 2 ( Fig. 4).

[0024] When the second stop 13 is pushed further forward, the spiral spring 11 is compressed so that the stop ball 12 of the first stop 10 contacts the second stop on its side facing the shift drum 2 ( Fig. 5).

[0025] The flexible first stop 10 is moved past the second stop during further movement of the shift drum 2 in the direction of arrow 8 and the first stop 10 relaxes into the space between the second stop 13 and the third stop 14. Due to the extended third stop 14 under the influence of the projection 16 of the second stop 13, the first stop 10 cannot pass the third stop 14 ( Fig. 6).

[0026] Therefore, the shift drum 2 is slightly rotated back in the opposite direction according to arrow 9, whereby the first stop moves the second stop back until the latter assumes a position at the end of the guide slot 15. Since in this position the relatively thin end of the projection 16 is arranged in the area of ​​the third stop 14, the latter is moved back into the retracted position under the action of the spring (not shown) ( Fig. 7).

[0027] To reach the parking lock position of the shift drum 2, it is moved in the opposite direction, thus in the direction of arrow 8, whereby the first stop 10 located between the second stop 13 and the third stop 14 can now be moved over the retracted third stop, corresponding to the movement over the stop 13 according to Fig. 3. In Fig. 8 shows the parking lock position of the shift drum 2, in which the first stop 10 occupies a position, with respect to the direction of the arrow 8, significantly behind the third stop 14.

[0028] Returning the shift drum 2 from its parking lock position to the first gear position is possible in a simple manner. It is only necessary to start from the parking lock position of the shift drum 2 according to Fig. 8, to move the shift drum 2 back in the direction of arrow 9, whereby the flexible first stop 10, as for Fig. 3 illustrates, but in the opposite direction, the third stop 14 and then the second stop 13.

[0029] Thus, a mechanical device 18 is proposed which, depending on the direction of movement or rotation of the shift drum 2, initially prevents the shift drum from reaching a specific position by means of a positive locking mechanism that can be activated by overtraveling a specific position. Release of the shift drum 2 to reach the initially blocked position occurs by first retracting the shift drum 2 from the blocked position over a specific distance or angle, thereby releasing the lock again by overtraveling.

[0030] The device 18, which serves to limit the travel of the shift drum 2, allows the parking lock to be activated only after release. In this case, the engagement occurs, in particular, in an additional shift drum track. List of reference symbols 1 axis 2 shift drum 3 backdrop 4 backdrop 5 Switch pin 6 Switch pin 7 Stationary part 8 Arrow 9 Arrow 10 First attack 11 Spiral spring 12 stop ball 13 Second attack 14 Third attack 15 Guide slot 16 Approach 17 area 18 Device 19 Distance measure

Claims

[1] Device for preventing unintentional activation of a parking lock function in a 2-speed transmission, wherein gearshift positions of the transmission and its parking lock function can be accessed via a shift drum (2), wherein a mechanically active device (18) is provided which, when the shift drum (2) rotates in a first direction of rotation (8), blocks the approach to a parking lock position of the shift drum (2), then releases the blocking when the shift drum (2) rotates in a second direction of rotation (9) opposite to the first direction of rotation (8) and then allows the approach to the parking lock position in the first direction of rotation (8) opposite to the second direction of rotation (9). [2] Device according to claim 1, wherein the device (18) positively blocks the approach to the parking lock position of the shift drum (2). [3] Device according to claim 1 or 2, wherein the shift drum (2) is rotated back by an angle of rotation in the second direction of rotation (9) which is smaller than the angle of rotation for reaching a shift position of the transmission, in particular a shift position of the first transmission gear. [4] Device according to one of claims 1 to 3, wherein the device (18) has two base parts (2, 7) movable relative to one another, a flexible first stop (10) mounted in the one, first base part (2), and second and third stops (13, 14) mounted in the other, second base part (7), wherein the second stop (13) is mounted in the second base part (7) so as to be displaceable to a limited extent in the relative movement directions of the base parts (2, 7), and the third stop (14) is displaceable perpendicular to the relative movement directions of the base parts (2, 7) in the direction of the first base part (2) and in the opposite direction, wherein during relative movement of the two base parts (2, 7), the second stop (13) is moved to a limited extent by means of the first stop (10), and in the process the third stop (14) extends in the direction of the first base part (2), such that, after a limited movement of the second stop (13) in the direction of the third stop (14),upon further relative movement of the two base parts (2, 7), the second stop (13) can be overridden by means of the first stop (10) and the third stop (14) cannot be overridden by means of the first stop (10). [5] Device according to claim 4, wherein the second stop (13) has a projection (16) which, when the second stop (13) is moved in the direction of the third stop (14), extends the third stop (14) in the direction of the first base part (2). [6] Device according to claim 4 or 5, wherein spring means are provided for biasing the third stop (14) into its retracted position. [7] Device according to one of claims 4 to 6, wherein the first stop (10) arranged between the second stop (13) and the third stop (14) pushes the second stop (13) back to a limited extent when the first stop (10) and the second stop (13) move towards each other and the second stop (13) releases the third stop (14), whereby the third stop (14) retracts. [8] Device according to claim 7, wherein when the second stop (13) is pushed back and the third stop (14) is retracted, the third stop (14) can be overridden by means of the first stop (10) in order to reach the parking lock position of the shift drum (2). [9] Device according to one of claims 4 to 8, wherein, starting from the parking lock position of the shift drum (2), the retracted third stop (14) and the second stop (13) can be overridden by means of the first stop (10) in order to reach a shift position of the transmission, in particular initially a shift position of the first transmission gear. [10] Device according to one of claims 4 to 9, wherein the first base part (2) is a component of the shift drum (2) or is connected to the shift drum (2) in a rotationally fixed manner, and the second base part (7) is stationary. [11] Device according to one of claims 1 to 10, wherein the two transmission gears can be shifted by means of a clutch and a shift claw. [12] Device according to claim 11, wherein the switching claw is associated with a freewheel. [13] Device according to claim 11 or 12, wherein in the first gear the clutch is open and the shift claw is closed, in the second gear the clutch is closed and the shift claw is open, and in the parking lock function of the transmission the clutch and the shift claw are closed.

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