parking lock, transmission and drive device

Abstract

A parking lock (1, 19, 24) for a motor vehicle has a movable locking device for striking a parking lock wheel (14) disposed inside a transmission housing (2) with a retaining force. The movable locking device is pivotable between a released state and a locked state via a shift shaft (3) rotatable by a drive motor (4) and a cam (7) coupled to the shift shaft (3). In the released state, the parking lock wheel (14) is rotatable; in the locked state, rotation of the parking lock wheel (14) is prevented. The drive motor (4) is disposed outside the transmission housing (2), the shift shaft (3) passes through the transmission housing (2), and the cam (7) is disposed inside the transmission housing (2). Furthermore, the present invention relates to a transmission having this type of parking lock (1, 19, 24) and a drive system for an electrically driven motor vehicle.

Description

Technical Field

[0001] The present invention relates to a parking lock for a motor vehicle having a movable locking device for striking a parking lock wheel disposed inside a transmission housing with a retaining force. Background Technology

[0002] Parking locks, also known as parking brakes, are increasingly used in motor vehicles. Here, a movable locking device operates on a parking lock wheel, which is connected to the vehicle's wheels via a transmission mechanism. In the locked state, the parking lock prevents the vehicle's wheels from moving.

[0003] In the general type of parking lock described in document WO2017 / 216230A1, a pushrod and a drive mechanism for the pushrod are housed within the transmission housing. The pushrod interacts with a single-sided rod having a protrusion that, upon actuation of the pushrod, is pivotable into a recess in the parking lock wheel.

[0004] However, this type of structure is complex. Separate wiring harnesses are required both inside and outside the transmission housing. Furthermore, transmission fluid must be prevented from entering the parking brake, especially its electric actuator, due to the pressure difference between the inside of the transmission housing and the parking brake. This type of design implementation, however, leads to increased structural complexity. Summary of the Invention

[0005] This invention is based on the purpose of specifying a parking lock for motor vehicles, which has a simple structure while ensuring reliable performance.

[0006] To achieve this objective, according to the present invention, in a parking lock of the type mentioned at the beginning, the movable locking device can pivot between a released state and a locked state via a shift shaft rotatable by a drive motor and a cam connected to the shift shaft. In the released state, the parking lock wheel can rotate, and in the locked state, the rotation of the parking lock wheel is prevented. The drive motor is located outside the transmission housing, the shift shaft passes through the transmission housing, and the cam is located inside the transmission housing.

[0007] The present invention is based on the concept that the parking lock's drive mechanism, particularly the electric drive mechanism, can be reliably protected from transmission fluid ingress because the drive motor is located outside the transmission housing. The shift shaft, driven by the drive motor, extends inward through the transmission housing and supports a pivotable cam. Therefore, only a single wiring harness located outside the transmission housing is required. Separate ventilation for the parking lock is unnecessary. Thus, the parking lock according to the present invention has a simple construction and ensures reliable performance.

[0008] The improvement of this invention lies in that the shift shaft is surrounded by a torsion spring, which is fastened to the shift shaft on one side and to a cam on the other. When the shift shaft pivots from the released state to the locked state, the torsion spring moves the cam that prevents the parking lock wheel from moving.

[0009] When the parking lock moves from the non-braking, inactive position (i.e., the released state) to the braking position (i.e., the locked state), torque is transmitted from the shift shaft to the cam via a torsion spring. Due to the rotation of the shift shaft in the (first) rotational direction via the torsion spring, the cam can thus transition from the released state to the locked state.

[0010] In this invention, a pawl is preferably provided on the shift shaft. The pawl allows the cam to transition from a locked state to a released state by rotation of the shift shaft in the opposite direction to the rotation direction.

[0011] In this invention, the cam can be specified to have a channel opening adapted to the outer diameter of the shift shaft. The cam is thus configured to be separate from the shift shaft and rotatable at least about portions of the shift shaft. The cam and the shift shaft are interconnected by a torsion spring.

[0012] To ensure that the operation of the parking lock according to the invention has particularly low friction, the shift shaft can be mounted on or within the transmission housing via friction bearings or roller bearings. The mounting of the shift shaft reduces friction, thus reducing the required output of the electric drive system.

[0013] One embodiment of the invention specifies that the shift shaft is sealed relative to the transmission housing by a sealing element. The sealing element prevents contaminants from entering the transmission housing and also prevents transmission fluid from leaking to the outside through the transmission housing.

[0014] When the shift shaft is mounted in the transmission housing via its free end opposite the drive motor, the parking lock according to the invention can apply a particularly high holding force. The free end of the shift shaft is preferably mounted in a blind hole in the transmission housing or transmission cover via a roller bearing or friction bearing. The free end of the shift shaft may also be provided with a spacer sleeve, thus positioning the shift shaft axially.

[0015] The present invention also relates to a transmission having a parking lock of the type described above.

[0016] Furthermore, the present invention also relates to a drive device for an electrically driven motor vehicle, the drive device comprising an electric motor, a transmission coupled to the electric motor, and a parking lock of the type described above. Attached Figure Description

[0017] The invention will now be explained in more detail with reference to the accompanying drawings and exemplary embodiments. The drawings are schematic diagrams, in which:

[0018] Figure 1 The main components of the parking lock according to the invention in the transmission housing are shown;

[0019] Figure 2 An axial view of the parking lock is shown, with the parking lock wheel blocked.

[0020] Figure 3 The image shows the released state. Figure 2 The parking lock shown;

[0021] Figure 4 An enlarged view of the cams mounted on the shift shaft is shown when viewed along the longitudinal direction of the shift shaft.

[0022] Figure 5 An axial view is shown, illustrating another exemplary embodiment of the parking lock according to the present invention; and

[0023] Figure 6 An axial view of another exemplary embodiment of the parking lock according to the present invention is shown. Detailed Implementation

[0024] Figure 1 A parking lock 1 is shown, housed within the transmission housing 2. The parking lock 1 includes a shift shaft 3 rotatable by an electric drive motor 4. For this purpose, the shift shaft 3 is connected to the drive shaft of the drive motor 4. Figure 1 As can be seen, the electric drive motor 4 is disposed outside the transmission housing 2, which is shown in cross-section. The shift shaft 3 passes through the opening 5 of the transmission housing 2. Except for the portion directly adjacent to the electric drive motor 4, the largest portion of the shift shaft 3 is disposed inside the transmission housing 2. The opening 5 is sealed by a sealing element 6. The seal 6 seals the annular space between the opening 5 of the transmission housing 2 and the outer side of the shift shaft 3.

[0025] A cam 7 is mounted on the shift shaft 3, wherein the shift shaft 3 and the cam 7 are constructed as separate components. The cam 7 has a channel opening adapted to the outer diameter of the shift shaft 3, allowing the cam 7 to be pushed onto the end of the shift shaft 3. The shift shaft 3 is surrounded by a torsion spring 8. One end of the torsion spring 8 ( Figure 1 The left end of the torsion spring 8 is supported on and secured to the shift shaft 3. The other end of the torsion spring 8 ( Figure 1 The right end of the shift shaft 3 is supported on and fastened to the cam 7. The shift shaft 3 has a disc 9 in its free end region, which fixes the cam 7 in the axial direction.

[0026] Figure 2The parking lock 1 is shown in an axial view, i.e., along the longitudinal direction of the shift shaft 3. A plate 10 made of steel alloy is located on the inner side of the transmission housing 2. The plate 10 is disposed between the cam 7 and the inner side of the transmission housing 2 and is located opposite to the cam 7. When the cam 7 rotates, the cam 7 contacts the plate 10, i.e., the cam 7 rolls on the plate 10 but does not contact the transmission housing 2.

[0027] Figure 2 A cam 7 is shown, approximately in its maximum "extended" position, with the tip of the cam 7 at its lowest point. The cam 7 contacts a movable locking device configured as a latch via its tip 11. One end (not shown) of the latch 12 is pivotally mounted. The latch 12 has a laterally projecting protrusion 15 near its free end. When the cam 7 pivots the latch 12, the protrusion 15 of the latch 12 moves against the force of a spring (not shown) into the recess 13 of the parking lock wheel 14. In this state, the protrusion 15 of the latch 12 prevents rotation of the parking lock wheel 14, which is connected to the wheel of the motor vehicle via a transmission. Figure 2 The parking lock 1 shown in the locked state prevents the wheels of the motor vehicle from rotating. A control device (not shown) controls the electric drive motor 4, which drives the shift shaft 3 and thus the cam 7.

[0028] Figure 3 It is similar to Figure 2 The view shows the parking lock 1 on cam 7 from... Figure 1 The image shows an axial view of the vehicle rotating clockwise from the indicated position. The tip 11 of the cam 7 slides along the outer side of the locking latch 12. As a result, the locking latch 12 moves away from the parking lock wheel 14 along the direction of the cam 7 under the action of a spring acting on the locking latch 12. In this state, the protrusion 15 of the locking latch 12 is outside the recess 13 of the parking lock wheel 14, so that the rotation of the parking lock wheel 14 is no longer hindered. Therefore, the wheels of the motor vehicle connected to the parking lock wheel 14 can move.

[0029] therefore, Figure 3 The parking lock 1 is shown in an inactive (released) state, while Figure 2 The parking lock 1 is shown in the locked state, in which rotation of the parking lock wheel 14 is prevented. From Figure 3 Starting from the state shown, cam 7 can be switched from the released state to the locked state by rotating shift shaft 3 counterclockwise. Shift shaft 3 transmits torque to cam 7 via torsion spring 8.

[0030] If the protrusion 15 of the locking latch 12 is not located above the recess 13 of the parking lock wheel 14, the protrusion cannot move into the recess and instead rests on the outer periphery of the parking lock wheel 1. The torque transmitted by the shift shaft 3 has the effect of tensioning the torsion spring 8, i.e., potential energy is stored in the torsion spring 8. As the vehicle equipped with the parking lock continues to roll, the parking lock wheel 14 rotates. Under the pre-tension force generated by the torsion spring 8, the locking latch 12 is then pushed into the next recess 13, thus locking the parking lock 1.

[0031] Figure 4 An axial view of cam 7, located on shift shaft 3, is shown. It can be seen that cam 7 has a channel opening 16 in this region that corresponds to the outer diameter of shift shaft 3. Torsion spring 8 can hook into a second, smaller channel opening 17 of cam 7. Figure 4 As can be seen, the cam 7 has a pawl 18, which allows the cam 7 to directly switch from the locked state to the released state during the clockwise rotation of the shift shaft 3, without the involvement of the torsion spring 8.

[0032] Figure 5 A partial cross-sectional view of a second exemplary embodiment of the parking lock 19 is shown, wherein the same components are identified by the same reference numerals. In the same manner as the first exemplary embodiment, the parking lock 19 includes a shift shaft 3, which partially passes through and is primarily housed within the transmission housing 2. The shift shaft 3 is driven by an electric drive motor 4. A cam 7 coupled to the shift shaft 3 serves to prevent the locking latch 12 of the parking lock wheel 14 from engaging. Figure 5 In this configuration, a spacer sleeve 20, mounted via a bearing 21 in a blind hole 22 of the transmission housing cover 23, is positioned at the right end of the shift shaft 3. Due to this support at the end of the shift shaft 3 opposite to the drive mechanism, the shift shaft 3 can transmit higher torque.

[0033] Figure 6 A third exemplary embodiment of the parking lock 24 is shown, wherein the same components are again provided with the same reference numerals as in the aforementioned exemplary embodiments. The shift shaft 3, housed in the transmission housing 2, is located at the free end of the shift shaft 3, i.e. Figure 6 The right end of the shift shaft 3 is mounted in plate 25, which is positioned perpendicular to the longitudinal direction of the shift shaft 3. Plate 25 is fastened to plate 10, which is located inside the transmission housing 2 and has a circular opening into which the end 26 of the shift shaft 3 is inserted and mounted. Due to this support, the shift shaft 3 is able to transmit higher torque.

Claims

1. A parking lock (1, 19, 24) for a motor vehicle, having a movable locking device for striking a parking lock wheel (14) disposed inside a transmission housing (2) with a retaining force, characterized in that, The movable locking device is pivotable between a released state and a locked state via a shift shaft (3) rotatable by a drive motor (4) and a cam (7) connected to the shift shaft (3). In the released state, the parking lock wheel (14) is rotatable, and in the locked state, rotation of the parking lock wheel (14) is prevented. The drive motor (4) is located outside the transmission housing (2), the shift shaft (3) passes through the transmission housing (2), and the cam (7) is located inside the transmission housing (2). A plate (10) is arranged between the cam (7) and the interior of the transmission housing (2) such that the cam (7) contacts the plate (10) as the cam (7) rotates.

2. The parking lock according to claim 1, wherein, The shift shaft (3) is surrounded by a torsion spring (8), which is fastened to the shift shaft (3) on one hand and to the cam (7) on the other.

3. The parking lock according to claim 2, wherein, Due to the rotation of the shift shaft (3) in the rotational direction by the torsion spring (8), the cam (7) can switch from the released state to the locked state.

4. The parking lock according to claim 3, wherein, By means of a pawl (18) provided on the shift shaft (3), the cam (7) can be switched from the locked state to the released state via the shift shaft (3) in the opposite direction of rotation.

5. The parking lock according to any one of claims 2 to 4, wherein, The cam (7) in the locked state strikes the locking latch (12) and pushes the locking latch (12) into the recess (13) of the parking lock wheel (14).

6. The parking lock according to claim 5, wherein, When the locking latch (12) is not located opposite the recess (13) of the parking lock wheel (14), the torque transmitted by the shift shaft is stored as potential energy in the torsion spring (8), wherein the locking latch (12) is pushed into the recess (13) of the parking lock wheel (14) during further rotation of the parking lock wheel (14).

7. The parking lock according to any one of claims 1 to 4, wherein, The cam (7) has a channel opening (16) adapted to the outer diameter of the shift shaft (3).

8. The parking lock according to any one of claims 1 to 4, wherein, The shift shaft (3) is mounted on the transmission housing (2) or in the transmission housing (2) via a friction bearing or a roller bearing.

9. The parking lock according to any one of claims 1 to 4, wherein, The shift shaft (3) is sealed relative to the transmission housing (2) by a sealing element (6).

10. The parking lock according to any one of claims 1 to 4, wherein, The shift shaft (3) is mounted in the transmission housing (2) through the free end of the shift shaft (3) opposite to the drive motor (4).

11. A transmission comprising a parking lock (1, 19, 24) according to any one of claims 1 to 10.

12. A drive system for an electrically driven motor vehicle, comprising: - Electric motor; - The gearbox connected to the motor, and - The parking lock (1, 19, 24) according to any one of claims 1 to 10.

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