Hydraulic park lock actuation module

Abstract

The invention relates to a hydraulic parking lock actuation module (10) for a parking lock with a parking lock piston (2) which can be actuated hydraulically in an actuation direction from a starting position in a parking lock cylinder (1) by applying an actuation pressure and which is coupled mechanically to an actuation lever (4) which can be fixed via an engagement device in order to serve as a locking mechanism (7) for the parking lock piston. In order to simplify the actuation of the parking lock, the hydraulic parking lock actuation module (10) comprises only one active actuation valve (18) for actuating the parking lock piston (2) and the locking mechanism (7) for the parking lock piston (2), which has a tank connection (11) and a working pressure connection (12) at which different hydraulic pressure levels are applied.

Description

Technical Field

[0001] This invention relates to a hydraulic parking lock actuation module for a parking lock having a parking lock piston, the parking lock piston being hydraulically actuated from an initial position along the actuation direction within a parking lock hydraulic cylinder by applying actuation pressure, and the parking lock piston being mechanically coupled to an actuation rod, which can be fixed via a coupling device to serve as a locking mechanism for the parking lock piston. The invention also relates to a method for operating a parking lock having such a parking lock actuation module. Background Technology

[0002] A hydraulic device with a pump is known from German patent application DE 10 2018 112 670 A1. This device can be connected to a cooling line for supplying hydraulic medium to a first consumable for cooling and / or lubrication, and can be connected to an actuation line for supplying a second consumable. The device can also be connected to the same hydraulic device to actuate it. The pump is designed as a reversing pump. A hydraulic parking lock actuator with a double-acting piston can be supplied with hydraulic fluid for actuating the parking lock. The parking lock actuator can be fixed in place via a latching device, which has a spring-pretensioned blocking element sized and arranged to engage in a contra-shaped recess. The piston is provided with a pull mechanism for emergency unlocking. Summary of the Invention

[0003] The purpose of this invention is to simplify the actuation of a parking lock with a parking lock piston, which can be hydraulically actuated in the parking lock hydraulic cylinder from an initial position along the actuation direction by applying actuation pressure, and the parking lock piston is mechanically connected to an actuation rod, which can be fixed via a coupling device so as to serve as a locking mechanism for the parking lock piston.

[0004] This objective is achieved by a hydraulic parking lock actuation module for a parking lock having a parking lock piston, which is hydraulically actuated in the parking lock hydraulic cylinder from an initial position along the actuation direction by applying actuation pressure, and the parking lock piston is mechanically coupled to an actuation rod, which can be fixed via a coupling device to serve as a locking mechanism for the parking lock piston. The hydraulic parking lock actuation module comprises only one active actuation valve for actuating the parking lock piston and for the locking mechanism of the parking lock piston, the active actuation valve having a tank connection and a working pressure connection at which different hydraulic pressure levels are applied. The two different hydraulic pressure levels are advantageously provided by a known hydraulic subsystem. For example, in terms of the hydraulic subsystem, a larger volumetric flow rate provides a lower pressure for cooling and / or lubrication. A lower volumetric flow rate with higher pressure is provided for hydraulic actuation of at least one hydraulic actuation element and the parking lock. Preferably, a hydraulic pump, particularly a tandem pump that can only deliver in one direction, is used to provide the different hydraulic pressure levels. Therefore, the use of a reversing pump, known in the prior art and capable of conveying in opposite directions, can be eliminated. Regarding reversing pumps, a hydraulic parking lock actuator with a double-acting piston for this purpose, known from German patent application DE 10 2018 112 670 A1, can be actuated in opposite actuation directions. In contrast, the parking lock piston with the claimed parking lock actuation module can only be hydraulically actuated in one actuation direction. With this hydraulic parking lock actuation module, the parking lock can be simplified by combining a single active actuation valve with different hydraulic pressure levels without sacrificing functionality, particularly functionality related to manufacturing costs. Hydraulic actuation in one actuation direction moves the parking lock piston to the actuated position, in which the parking lock is preferably opened, disengaged, or deactivated. This type of parking lock is also referred to as a "normally holding" parking lock that is opened by hydraulic actuation. "Normally holding" means that the parking lock remains in its current state. The parking lock piston is cost-effectively designed as a single-acting piston. Regarding the actuation valve, "active" means that it can be actively actuated, for example, via an electrically controlled solenoid, to actively switch the actuation valve from its first switching position to a second switching position.

[0005] A preferred exemplary embodiment of the hydraulic parking lock actuation module is characterized in that the module includes a locking element movable between a released position and a locked position, and in its locked position, the locking element engages in a latch recess on the actuating rod, wherein the locking element is pre-tensioned by a locking spring into the locked position. For example, the locking element is a locking pin that can move substantially laterally to the actuating rod. The latch recess is, for example, a latch groove in which one end of the locking element, particularly the locking pin, engages to lock the actuating rod or parking lock piston connected to the locking element. This provides an efficient and inexpensive locking mechanism.

[0006] Another preferred exemplary embodiment of the hydraulic parking lock actuation module is characterized in that the locking element is provided with a release piston, which can be hydraulically actuated against the pretension force of the locking spring via an actuation valve in a release cylinder, and the release piston moves the locking element from the locked position to the released position. Therefore, the actuation valve for the parking lock piston can advantageously be used to release the locking element or unlock the locking element. Thus, the release piston can also be referred to as an unlocking piston. The release piston is also cost-effectively designed as a single-acting piston. In this way, design effort and manufacturing costs can be further reduced.

[0007] Another preferred exemplary embodiment of the hydraulic parking lock actuation module is characterized in that, in addition to the tank connection and the working pressure connection, the actuation valve also includes a parking lock actuation connection and a release connection, and different hydraulic pressure levels can be applied to the parking lock actuation connection and the release connection via the actuation valve. Therefore, other valves can be advantageously omitted from the hydraulic parking lock actuation module.

[0008] Another preferred exemplary embodiment of the hydraulic parking lock actuation module is characterized in that the actuation valve is designed as a 4-way / 2-way valve. In this way, all the desired functions of convenient operation of the parking lock can be achieved with only a single actuating valve. The 4-way / 2-way valve is preferably actuated electrically or electromagnetically and is pre-tensioned by a spring in one of the two positions.

[0009] Another preferred exemplary embodiment of the hydraulic parking lock actuation module is characterized in that the locking element is provided with an electrically actuated linear actuator for moving the locking element from a locked position to a released position. This electrically actuated linear actuator is, for example, an electrically actuated lifting magnet. In this way, the locking element can be redundantly released or unlocked via the electrically actuated linear actuator or by hydraulic actuation of a release piston.

[0010] Another preferred exemplary embodiment of the hydraulic parking lock actuation module is characterized in that a return spring is associated with the parking lock piston so as to reset the parking lock piston when the pressure on the parking lock piston in the parking lock hydraulic cylinder is reduced from a high pressure level to a low pressure level via an actuation valve. Therefore, in combination with a hydraulically actuated release piston or an electrically actuated linear actuator, it is ensured that the parking lock can engage when a motor vehicle equipped with a parking lock is parked.

[0011] Another preferred exemplary embodiment of the hydraulic parking lock actuation module is characterized in that the actuation rod has two latching recesses to lock the parking lock piston in its basic position and hydraulically actuated position. Therefore, in certain operating states, the number of valve changes required can be reduced.

[0012] In the method for operating a parking lock having a hydraulic parking lock actuation module as described above, the aforementioned objective is alternatively or additionally achieved by connecting the parking lock hydraulic cylinder to the tank connection via an actuation valve, wherein the parking lock piston is held in its basic position by a return spring, and wherein the locking element is held in its locked position by a locking spring. In this way, all the desired functions of the parking lock operation can be achieved using only one active actuation valve and two hydraulic pressure levels.

[0013] A preferred exemplary embodiment of this method is characterized in that, in order to open the parking lock, a high pressure level is applied to the parking lock actuation connection via an actuation valve. If only one latch recess is used, the actuation rod is released via the locking element, so no preparation is required. When using a second latch recess, the locking element must be released in advance.

[0014] The present invention may also relate to various parts of a hydraulic parking lock actuation module, such as the parking lock piston, parking lock hydraulic cylinder, actuating rod and / or locking mechanism, particularly the locking element, and / or actuating valve. The mentioned parts can be addressed individually. Attached Figure Description

[0015] Other advantages, features, and details of the invention will become apparent from the following description, in which various exemplary embodiments are described in detail with reference to the accompanying drawings. In the drawings:

[0016] Figure 1 A schematic diagram of a hydraulic parking lock actuation module having an actuating valve and a locking mechanism according to a first exemplary embodiment is shown;

[0017] Figure 2 It shows the relationship with Figure 1 An exemplary embodiment with a slightly modified actuator valve, similar to the exemplary embodiment described above;

[0018] Figure 3 It shows the relationship with Figure 2 An exemplary embodiment with a reversing actuator valve, similar to the exemplary embodiment described above;

[0019] Figure 4 It shows the use for Figures 1 to 3 The diagram shows a hydraulic subsystem with two different hydraulic pressure levels provided by the hydraulic parking lock actuation module.

[0020] Figure 5 This shows the various operating states indicated by the capital letters A to I. Figure 1 Hydraulic parking lock actuation module;

[0021] Figure 6 Showing from Figure 1 A perspective view of a specific implementation of the hydraulic parking lock actuation module;

[0022] Figure 7 Showing from Figure 6 A longitudinal cross-sectional view of the hydraulic parking lock actuation module; and

[0023] Figure 8 Showing from Figure 6 Another longitudinal section of the hydraulic parking lock actuation module. Detailed Implementation

[0024] Figures 1 to 3 Three variant implementations of the hydraulic parking lock actuation module 10; 20; 30 are schematically shown. The hydraulic parking lock actuation module 10; 20; 30 includes a parking lock hydraulic cylinder 1, within which a parking lock piston 2 can move along... Figures 1 to 3 The horizontal movement is repeated. The parking lock piston 2 in the parking lock hydraulic cylinder 1 is pre-tensioned by the reset spring 3. Figures 1 to 3 The parking lock piston is shown in its basic position.

[0025] exist Figures 6 to 8 In the middle, different views are shown from Figure 1 The specific implementation method of the hydraulic parking lock actuation module. Figure 1 as well as Figures 6 to 8 The same reference numerals are used to denote the various parts.

[0026] The parking lock is actuated using hydraulic parking lock actuation modules 10, 20, and 30. Figures 6 to 8 The parking lock 60 is indicated only by reference numeral 60 in the accompanying drawings. For example, the parking lock 60 is connected via a parking lock lever (not shown) that interacts with the parking lock mechanism (not shown). Figure 6 and Figure 7 (61) For example, it is mechanically actuated. Such parking lock mechanisms include, for example, parking lock wheels.

[0027] The actuating lever 4 is fastened to the parking lock piston 2. The actuating lever 4 includes a latching recess 6, and one end of the locking element 5 is latched into the latching recess to form a locking mechanism 7 for the actuating lever 4.

[0028] The locking mechanism 7 includes a release piston 8 to which the locking element 5 is attached. Figures 1 to 3 In the middle, the release piston 8 is pre-tensioned upward by the locking spring 9. The locking element 5 is pressed by the pre-tension force of the locking spring 9 along the direction of the latch recess 6 on the actuator rod 4. In addition, the locking element 5 is provided with a linear actuator 15, which is designed, for example, an electrically lifting magnet.

[0029] The release piston 8 can withstand the pressure in the release cylinder 16 on the side opposite to the locking spring 9. The parking lock piston 2 can withstand the pressure in the parking lock hydraulic cylinder 1 on the side opposite to the return spring 3. The parking lock piston 2 or the release piston 8 can withstand pressures of varying hydraulic pressure levels by applying appropriate pressure via the actuation valve 18.

[0030] The actuation valve 18 is designed as a 4-way / 2-way valve having a tank connection 11, a working connection 12, a parking lock actuation connection 13, and a release connection 14. The actuation valve 18 can be actuated electromagnetically. The actuation valve 18 is pre-tensioned by a symbolically indicated spring. Figures 1 to 3 The position of the actuation valve is shown.

[0031] The parking lock actuation connection 13 is connected to the parking lock hydraulic cylinder 1. The release connection 14 is connected to the release cylinder 16. The tank connection 11 is connected to a tank or hydraulic medium reservoir. The working connection 12 can be connected via... Figure 4 The hydraulic subsystem 40 shown is subjected to different hydraulic pressure levels.

[0032] Figure 4 The hydraulic subsystem 40, schematically shown, includes two hydraulic actuation units 41 and 42 and a cooling and / or lubrication device 43 having hydraulic medium from a hydraulic medium reservoir 44, also referred to as a tank. The hydraulic medium is drawn from the hydraulic medium reservoir 44 via a suction filter 45 having a series pump 46.

[0033] The series pump 46 is driven by an electric motor and includes a first pump 47 and a second pump 48. As symbolically indicated, both pumps 47 and 48 are driven by the same electric motor. As indicated by the larger pump symbol, pump 47 is designed to provide a larger volumetric flow rate at low pressure. The second pump 48 is designed to deliver a smaller volumetric flow rate at high pressure.

[0034] like Figure 4As shown, both pumps 47 and 48 can be used to provide volumetric flow to the cooling and / or lubrication device 43 via system pressure valve 50. Two hydraulic actuation units 41 and 42 can be hydraulically actuated independently of each other using high pressure, provided by the second pump 48 via hydraulic valves 51 and 52 in conjunction with check valves 53 and 54. The hydraulic actuation units 41 and 42 are, for example, clutches or brakes.

[0035] Additionally, when the system pressure valve 50 is closed, the second pump 48 can provide high pressure at the working connection 12 of the parking lock. When the system pressure valve 50 is open, low pressure can also be provided at the working connection 12 of the parking lock. The two hydraulic pressure levels available at the working connection 12 can be advantageously used for the parking lock via the actuation valve 18. Figures 6 to 8 60 in the middle) and Figure 1 Comfort actuation is achieved through the hydraulic parking lock actuation module 10.

[0036] exist Figure 5 In the middle, uppercase letters A through I are used to indicate... Figure 1 The hydraulic parking lock actuation module 10 has different operating states. Operating state A refers to the parking lock being closed. For example, this operating state corresponds to the vehicle being stationary with the parking lock engaged. The parking lock hydraulic cylinder 1 is connected to the tank 11 via a de-energized actuation valve 18, such that the return spring 3 presses the parking lock piston 2 into the indicated basic position of the parking lock piston. The locking element 5, also known as the locking pin 5, is pressed against the actuation rod 4 by the locking spring 9.

[0037] Operational state B indicates that the parking lock is open: In order to open the parking lock, via the hydraulic subsystem ( Figure 4 (40) A high pressure level is provided at the working connection 12 of the actuation valve 18. At the same time, the actuation valve 18 is activated, in particular energized, so that the actuation valve 18 is switched and the high pressure level is switched to the parking lock hydraulic cylinder 1, thereby moving the parking lock piston 2 to the right to disengage the parking lock.

[0038] At the end of the actuation path, the locking element 5 is latched into the latch recess 6 on the actuating rod 4 due to the pretension of the locking spring 16. If the actuating valve 18 is now switched back to its basic position, or alternatively the pressure level at the working connection 12 is reduced, the locking element 5 resists the force of the return spring 3 to keep the actuating rod 4 open, and thus keeps the parking lock open.

[0039] Operating state C corresponds to the cooling mode. In normal drive operation, i.e., without actuating the hydraulic actuation unit (… Figure 4 In cases 41 and 42), active cooling and / or lubrication are present at the working connection 12 of the actuating valve 18. Figure 4The low pressure level of 43). For energy efficiency reasons, actuator valve 18 can remain de-energized.

[0040] Then, a low-pressure level for active cooling and / or lubrication is applied to the release cylinder 16. The locking spring 9 is advantageously designed to be very robust, such that the low-pressure level is insufficient to dislodge the locking element 5 from the latch recess 6. Therefore, the parking lock remains securely open even in cooling mode.

[0041] Operating state D indicates readiness for actuation. If you want to adjust the hydraulic actuation unit (... Figure 4 Actuating valves 41 and 42 in the system requires a higher pressure level. In the de-energized basic position of actuation valve 18, this pressure level pulls locking element 5 out of latch recess 6, causing the parking lock to close undesirably. Therefore, actuation valve 18 switches shortly before a higher system pressure becomes available.

[0042] Operating state E refers to actuation. The switching of actuation valve 18 is... Figure 5 The operating states B, D, E, and F are indicated by lightning bolt symbols. When actuation valve 18 switches, there is a higher system pressure at parking cylinder 1. This does not change the open state of the parking lock. At the same time, release cylinder 16 switches to tank connection 11, keeping actuation lever 4 locked.

[0043] Operating state F refers to post-processing of the actuation process. Shortly after the actuation process ends, when the hydraulic subsystem (… Figure 4 When the system pressure provided by 40) has dropped to the low pressure level of the cooling mode, the actuation valve 18 can be de-energized again.

[0044] Operating state G again corresponds to the cooling mode, which has been described with reference to operating state C.

[0045] Operating state H refers to engaging the parking lock. To close the parking lock and park the vehicle, this can be done by electrically actuating the linear actuator, particularly the lifting magnet 15, or by applying a high-pressure level to the release cylinder 16, causing the locking element 5 to pull out of the latch recess 6 and thus closing the parking lock. In operating states B, E, and H, the high-pressure level is indicated by a thick line at the working connection 12 of the actuator valve 18.

[0046] Operating state I refers to the parking lock being open, especially when the power is off. In special operating states, such as when pushing or towing a motor vehicle equipped with a parking lock, the parking lock can remain locked even when all systems are off, as in cooling mode, because locking element 5 keeps the parking lock open in both depressurization and power-off states.

[0047] exist Figure 2 In an alternative variant, an additional latch recess 26, particularly a latch groove, is provided on the actuating rod 4 for locking the parking lock mechanism in the P position. Furthermore, the backflow of the release cylinder 16 is preferably damped in a valve, as indicated by the throttle symbol 24 in valve 28. This ensures that the release piston 8 in the locking spring 9 can only be pushed back slowly.

[0048] This makes it possible that, in order to unlock the parking lock, the drive valve 18 is not connected to the hydraulic subsystem ( Figure 4 When high pressure is applied and energized, the locking element 5 is first pulled out of the latch recess 6, and then the actuation valve 28 is immediately switched so that the parking lock piston 2 moves under high pressure and thus opens the parking lock. This is possible because the locking element 5 is only slowly pushed back due to backflow damping and can no longer engage in the now displaced latch recess 6. The locking element 5 engages in the latch groove 26 only to hold the actuation rod 4 in the parking lock open position when the parking lock hydraulic cylinder 1 or the parking lock piston 2 is fully actuated. All other operating states are the same as those in the previous description. Figure 1 and Figure 5 This corresponds to the previous description.

[0049] Figure 3 The variant shown includes an actuation valve 38 that switches in reverse. In the de-energized basic position, the parking lock hydraulic cylinder 1 is connected to the working connection 12, and the release cylinder 16 is connected to the tank. In the activated second valve position, the parking lock hydraulic cylinder 1 is connected to the tank, and the release cylinder 9 is connected to the working connection 12.

[0050] and Figure 2 Similar to the variant, this variant also includes an additional latching groove 26 for locking the parking lock in the closed position. This has the advantage that when the working connection 12 is subjected to high pressure for hydraulic actuation unit (… Figure 4 When one of 41 and 42) is actuated, it is not necessary to switch actuation valve 18 beforehand. The actuation valve can remain in the basic de-energized position. On the one hand, this is energy-saving and does not require simultaneous control of all valves in the control electronics, because only the actuation valve 38 in the hydraulic parking lock actuation module 30 needs to be energized to close the parking lock.

[0051] This can be achieved in a hydraulic actuation unit ( Figure 4 (41, 42) occurs when no valve is actuated, and therefore only both valves need to be actuated simultaneously. Conversely, in Figure 1 and Figure 2 In the two variations mentioned above, the actuation valve 18 within the hydraulic parking lock actuation module 10; 20; 30 is connected to the system pressure valve ( Figure 450) must always be energized to provide high voltage.

[0052] However, with Figure 1 and Figure 2 Compared to the variants in, Figure 3 The variant has the following disadvantage: in the event of a power failure, the actuation valve 18 connects the parking lock hydraulic cylinder 1 to the tank, but instead connects it to the working connection 12. Therefore, the parking lock hydraulic cylinder 1 will empty more slowly than when it is connected to the tank, which can result in the parking lock closing less dynamically during power failures, especially in low temperatures.

[0053] List of reference numerals

[0054] 1 Parking lock hydraulic cylinder

[0055] 2 Parking lock piston

[0056] 3. Return spring

[0057] 4 Actuating rod

[0058] 5 Locking elements

[0059] 6 latch recess

[0060] 7. Locking mechanism

[0061] 8. Release the piston

[0062] 9. Locking spring

[0063] 10 Hydraulic parking lock actuation module

[0064] 11 Tank Connection Section

[0065] 12 Working connection parts

[0066] 13 Parking lock actuation connection part

[0067] 14. Release the connecting part

[0068] 15. Electrically Actuated Linear Actuator

[0069] 16 Release cylinder

[0070] 18 Actuation valve

[0071] 20 Hydraulic parking lock actuation module

[0072] 24 Throttling symbols

[0073] 26 Latch recess

[0074] 28 Actuation valve

[0075] 30 Hydraulic parking lock actuation module

[0076] 38 Actuation valve

[0077] 40 Hydraulic Subsystem

[0078] 41 Hydraulic Actuation Unit

[0079] 42 Hydraulic Actuation Unit

[0080] 43 Cooling and / or lubrication

[0081] 44 Hydraulic medium storage vessel

[0082] 45. Inhalation Filter

[0083] 46 Series Pumps

[0084] 47 First Pump

[0085] 48 Second Pump

[0086] 50 System pressure valve

[0087] 51 Hydraulic valve

[0088] 52 Hydraulic valve

[0089] 53 Check valve

[0090] 54 Check valve

[0091] 60 Parking Lock

[0092] 61 Parking Lock Bar

Claims

1. A hydraulic parking lock actuation module (10; 20; 30) for use in a parking lock (60) having a parking lock piston (2), the parking lock piston being hydraulically actuated in a parking lock hydraulic cylinder (1) from an initial position along the actuation direction by applying actuation pressure, and the parking lock piston being mechanically coupled to an actuation rod (4), the actuation rod being fixed via a coupling device for use as a locking mechanism (7) for the parking lock piston, characterized in that, For actuating the parking lock piston (2) and the locking mechanism (7) for the parking lock piston (2), the hydraulic parking lock actuation module (10; 20; 30) includes only one active actuation valve (18), which has a tank connection (11) and a working pressure connection (12) at which two different hydraulic pressure levels, high and low, are applied. The hydraulic parking lock actuation module (10; 20; 30) includes a locking element (5) which is movable between a release position and a locked position, and the locking element engages in a latch recess (6) on the actuation rod (4) in the locked position of the locking element. The locking element (5) is biased to the locked position by the locking spring (9), and the locking element (5) is provided with a release piston (8), which can be hydraulically actuated in the release cylinder (16) against the biasing force of the locking spring via the actuation valve (18), and the release piston moves the locking element (5) from the locked position of the locking element to the released position of the locking element. The locking spring (9) is designed to be very strong, such that a low hydraulic pressure level is insufficient to move the locking element (5) out of the latch recess (6), and a high hydraulic pressure level is sufficient to move the locking element (5) out of the latch recess (6). The actuation valve (18) is designed to be an electromagnetically controlled two-position four-way valve.

2. The hydraulic parking lock actuation module according to claim 1, characterized in that, In addition to the tank connection (11) and the working pressure connection (12), the actuation valve (18) also includes a parking lock actuation connection (13) and a release connection (14). The two different hydraulic pressure levels, high and low, can be applied to the parking lock actuation connection and the release connection via the actuation valve (18).

3. The hydraulic parking lock actuation module according to claim 2, characterized in that, The locking element (5) is provided with an electrically actuated linear actuator (15) for moving the locking element (5) from the locked position to the released position.

4. The hydraulic parking lock actuation module according to claim 2, characterized in that, The return spring (3) is associated with the parking lock piston (2) so as to reset the parking lock piston (2) when the pressure on the parking lock piston (2) in the parking lock hydraulic cylinder (1) is reduced from a high hydraulic pressure level to a low hydraulic pressure level via the actuation valve (18).

5. The hydraulic parking lock actuation module according to any one of claims 1-4, characterized in that, The actuating rod (4) has two latching recesses (6, 26) to lock the parking lock piston (2) in the basic position and the hydraulically actuated position of the parking lock piston.

6. The hydraulic parking lock actuation module according to any one of claims 1-4, characterized in that, The two different hydraulic pressure levels, high and low, are provided by a hydraulic subsystem (40), which includes a series pump (46) and a system pressure valve (50). When the system pressure valve is closed, the hydraulic subsystem (40) provides a high hydraulic pressure level to the working pressure connection (12), and when the pressure valve is open, the hydraulic subsystem (40) provides a low hydraulic pressure level to the working pressure connection (12).

7. A method for operating a parking lock having a hydraulic parking lock actuation module according to claim 4, characterized in that, When the parking lock (60) is closed, the parking lock hydraulic cylinder (1) is connected to the tank connection (11) via the actuation valve (18), wherein the parking lock piston (2) is held in the basic position of the parking lock piston by the return spring (3), wherein the locking element (5) is held in the locked position of the locking element by the locking spring (9).

8. The method according to claim 7, characterized in that, In order to open the parking lock (60), the high hydraulic pressure level is applied to the parking lock actuation connection (13) via the actuation valve (18).

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