Parking lock

Abstract

The invention relates to a parking lock (10) of a fluid-cooled electric axle module (1), which has at least one conveying unit (5) circulating a cooling fluid. The conveying unit is operated at a low pressure level. The parking lock (10) is assigned a hydraulic actuator (30) which is operated at a low pressure level of less than 3 bar. The invention also relates to the use of the parking lock (10) of a fluid-cooled electric axle module (10) in an electrically driven vehicle.

Description

[0001] Description

[0002] title

[0003] Technical field

[0004] The invention relates to a parking lock of a fluid-cooled e-axle module, which has at least one pump unit circulating a cooling fluid and operating at a low pressure. Furthermore, the invention relates to the use of the parking lock of a fluid-cooled e-axle module in an electrically powered vehicle.

[0005] State of the art

[0006] DE 10 2021 132 409 A1 discloses an electric drive for a vehicle with an optimized parking lock function. The described drive train is preferably used in a purely electric vehicle, wherein the maximum drive power of the two electric traction motors is at least approximately 100 kW. The electric traction motors are cooled with oil by means of an oil pump and corresponding heat exchangers. The oil pump has two streams, the lower-pressure stream serving to cool the electric traction motors as well as the transmission and for cooling and lubrication. The other, high-pressure stream of the oil pump is used for the hydraulic actuation of the parking lock mechanism. The oil pump generates different pressure levels.

[0007] DE 10 2021 213 980 A1 relates to a hydraulic system of an automatic transmission, in particular an electric vehicle axle. In one embodiment, a line can branch off from the hydraulic line of the hydraulic system towards a hydraulic parking lock cylinder with a parking lock piston. A parking lock connected to the parking lock piston can be moved into an engaged operating state by the system pressure applied to the parking lock piston. Furthermore, if a pressure in the hydraulic line, which is less than a threshold value and is applied to the parking lock piston, is present, the parking lock can be moved against the pressure in the hydraulic line into the designed state. In addition, in one embodiment, an electric motor of the electric vehicle axle can be supplied with oil for cooling via the low-pressure line.

[0008] DE 10 2021 120 782 A1 discloses a hydraulic arrangement for actuating hydraulic consumers and for cooling heat sources and / or lubricating components, particularly within a powertrain of a motor vehicle. In one embodiment, a hydraulic medium, such as oil, can be pumped in a hybrid module of a motor vehicle in a negative direction of rotation to cool a transmission and / or an electric motor, while in the positive direction of rotation, for example, a parking lock and / or a clutch is actuated. The parking lock can be arranged, in particular, in a hybrid module or an electric axle drivetrain of a motor vehicle and secure the vehicle against unintentional rolling away.

[0009] Disclosure of the invention

[0010] According to the invention, a parking lock for a fluid-cooled e-axle module is proposed, which has at least one pump unit circulating a cooling fluid and operating at a low pressure level, wherein the parking lock is associated with a hydraulic actuator operating at a pressure level of less than 3.0 bar. Advantageously, by integrating the parking lock into a fluid-cooled e-axle module, the existing cooling fluid circuit can be used to actuate the parking lock.

[0011] In an advantageous further development of the parking lock proposed according to the invention, it is designed such that the hydraulic actuator has a first pressure chamber, which represents a safety chamber, and a second pressure chamber, which serves as a working chamber.

[0012] The parking lock proposed according to the invention is designed such that the hydraulic actuator has a piston comprising a piston plate which is received within the second pressure chamber, which serves as the working chamber. Due to the prevailing low pressure level, a high hydraulic actuating force can be generated with appropriate dimensioning of the piston plate of the piston.

[0013] Advantageously, in the parking lock proposed according to the invention, the piston has a first locking groove and a second locking groove which, with respect to the length of the piston, lie within the first pressure chamber, which serves as a safety chamber.

[0014] In the parking lock proposed according to the invention, a spring-loaded locking pin is housed in the hydraulic actuator housing, corresponding to each of the locking slots. The spring-loaded locking pin is continuously pressed upwards by a corresponding spring force. As soon as the safety chamber is pressurized, the pressure acts downwards on the upper side of the spring-loaded locking pin. The dimensions of the locking pin ensure that the force generated by the pressure at a pressure of 3.0 bar is greater than the spring force acting on the locking pin, causing the locking pin to be moved downwards. This releases the locking pin.

[0015] In an advantageous further development of the parking lock proposed according to the invention, it is provided that it has a first compression spring which, in a parking position of the parking lock, holds the piston extended by a maximum extension distance.

[0016] In the parking lock proposed according to the invention, the second pressure chamber, which serves as a working chamber, is depressurized in the parking position, so that the spring force generated by the first compression spring is not reduced.

[0017] In the parking lock proposed according to the invention, the piston is locked in the first locking groove by means of the locking pin in the parked position. This ensures that the piston maintains its extension path, which defines the parked position.

[0018] The parking lock proposed according to the invention is advantageously designed such that the unlocking position of the parking lock is achieved by the locking pin disengaging from the first locking groove and by pressurizing the first pressure chamber, which serves as the working chamber. This ensures that the piston's return movement is initiated to the unlocking position due to the pressurization of the first pressure chamber, which serves as the working chamber.

[0019] In the parking lock proposed according to the invention, a pressure level is generated in the second pressure chamber, which serves as the working chamber, that produces a hydraulic force Fnydr exceeding the spring force Fs of the first compression spring. This ensures a safe return movement of the piston rod from the parked position to its unlocked position.

[0020] Furthermore, the invention relates to the use of the parking lock of a fluid-cooled e-axle module in an electrically powered vehicle.

[0021] Advantages of the invention

[0022] The parking lock proposed according to the invention for a fluid-cooled e-axis module advantageously allows a pumping unit operating at a low-pressure level to be used as an actuator for the parking lock. This enables the system to be actuated by hydraulic valves or other actuators that increase or decrease the pressure in both chambers; furthermore, a pumping unit already operating at a low-pressure level can be used for the cooling level within the framework of multiple functionalities.

[0023] Furthermore, the solution proposed according to the invention, the integration of the parking lock into the fluid-cooled e-axle module, saves installation space outside the e-axle module.

[0024] By eliminating the need for a separate conveying unit covering a low-pressure level, weight can be saved, as additional fluid conveying components can be omitted.

[0025] In the solution proposed according to the invention, the required system pressure is in the low-pressure range and is a maximum of 3.0 bar, which allows the use of an existing pump in the thermal cooling circuits of oil-cooled electrically powered vehicles. The system pressure level required for operation can be advantageously reduced further by appropriately adjusting the dimensions of a hydraulic actuator.

[0026] Brief description of the drawings

[0027] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0028] They show:

[0029] Figure 1 shows a schematic representation of an E-axle module embedded in an oil circuit.

[0030] Figure 2 Components of a parking lock operated by means of a hydraulic actuator,

[0031] Figure 2.1 shows a perspective view of the hydraulic actuator.

[0032] Figure 3 shows a longitudinal section through the hydraulic actuator according to Figure 2.1 ,

[0033] Figure 3.1 is a perspective view of the longitudinal section according to Figure 3.

[0034] Figure 4 shows a longitudinal section through the hydraulic actuator in the parked position.

[0035] Figure 4.1 shows the cone stroke pressure in the working chamber and the pressure in the safety chamber, plotted against time.

[0036] Figure 5 shows the unlocking of the piston of the hydraulic actuator by means of a locking pin,

[0037] Figure 5.1 shows the states of cone stroke pressure in the safety chamber and pressure in the working chamber for the position shown in Figure 5.

[0038] Figure 6 shows the actuating piston retracting into the housing of the hydraulic actuator when the working chamber is pressurized. Figure 6.1 shows the states of cone stroke pressure in the safety chamber and pressure in the working chamber corresponding to Figure 6.

[0039] Figure 7 shows the locking of the piston by means of the safety pin in the unlocked position of the parking lock,

[0040] Figure 7.1 shows the associated parameters of cone stroke pressure in the safety chamber and pressure in the working chamber according to Figure 6.

[0041] Figure 8 shows the unlocked position of the parking lock, secured by the locking pin and

[0042] Figure 8.1 shows the parameters of cone stroke pressure in the safety chamber and pressure in the working chamber belonging to the unlocking position of the parking lock according to Figure 8.

[0043] Embodiments of the invention

[0044] In the following description of embodiments of the invention, identical or similar elements are designated by the same reference numerals, and repeated descriptions of these elements are omitted in individual cases. The figures represent the subject matter of the invention only schematically.

[0045] Figure 1 shows an e-axle module 1, which houses an electric motor 2 and a gearbox 3. The e-axle module 1 is embedded in a fluid circuit, preferably an oil circuit 4, which supplies the components with a cooling fluid and / or lubricant in the form of circulating oil. A heat exchanger 7 is integrated into the oil circuit 4, as shown schematically in Figure 1. Temperature and pressure sensors may be located upstream and downstream of the heat exchanger 7, respectively. A pumping unit 5, preferably an oil pump, is also integrated into the oil circuit 4, as shown schematically in Figure 1. This pump is designed to operate at a low pressure below 5 bar, preferably at approximately 3 bar or below. A filter 9 is located upstream of the pumping unit 5.The oil circuit 4 is closed by an oil sump 6, in which the circulating fluid, preferably oil, is pumped back and from which it is also extracted before passing the filter 9, which is located upstream of the pumping unit 5.

[0046] Furthermore, as shown in Figure 1, a parking lock 10, designed as a hydraulic actuator 30, is integrated into the oil circuit 4 as depicted in Figure 1. The hydraulic actuator 30 comprises a piston 56 movable within a housing (not shown in detail here) and can be locked in positions by means of a locking pin 62, which will be described in more detail below.

[0047] The parking lock 10, which is actuated by an actuator 12, can be seen in Figure 2. In the illustration in Figure 2, the actuator 12 is designed as a hydraulic actuator 30. The parking lock 10 also includes a ratchet wheel 14, which has a number of teeth 18 along its circumference 16. These teeth are separated from each other in the circumferential direction by tooth gaps 20. A pawl 22 engages in the tooth gaps 20 on the circumference 16 of the ratchet wheel 14. The pawl is rotatable about a pivot axis 24 and can be pre-tensioned by a tension spring 26, for example, a torsion spring.

[0048] Figure 2.1 shows an enlarged perspective view of the hydraulic actuator 30 of the parking lock 10 proposed according to the invention. This is integrated into the e-axle module 1 of an electrically driven vehicle. The e-axle module 1 is a fluid-cooled e-axle module and is cooled, for example, by means of an oil circuit 4. The oil circuit 4 comprises a pumping unit 5 in the form of an oil pump, which circulates the cooling fluid, preferably oil, within the fluid-cooled e-axle module 1 at a low pressure level, preferably less than 3 bar. The hydraulic actuator 30 is connected to the cooling fluid circuit 4 within the e-axle module 1, as shown in Figure 2.1. The interfaces to the oil circuit 4 of the fluid-cooled e-axle module 1 are provided by the first hydraulic connection 34 and the second hydraulic connection 36, respectively, as shown in Figure 2.1.Figure 1 further shows that the housing 32 of the hydraulic actuator 30 has a retaining ring 38 on its end face, against which a plate 52, shown in section in Figure 3, is supported and fixed in the housing 32 of the hydraulic actuator 30. A first compression spring 40 is supported against said plate 52 and acts on a plate 48. A second compression spring 44 is connected to the first compression spring 40 by means of an offset piece 42, the second compression spring 44 acting on an actuating cone 46.

[0049] Figure 3 shows a longitudinal section through the hydraulic actuator 30 of the actuator 12, which is shown in perspective in Figure 2.1.

[0050] The longitudinal section according to Figure 3 shows that a longitudinally movable piston 56 is accommodated in the housing 32 of the hydraulic actuator 30.

[0051] The piston 56 essentially extends through the entire housing 32 of the hydraulic actuator 30. A pressure plate 58 is mounted on the circumference of the piston 56, for example via a screw connection. The pressure plate 58 is located in the area of ​​the housing 32 of the hydraulic actuator 30 in which the first pressure chamber, which functions as the working chamber 80, is formed.

[0052] Furthermore, a first locking groove 74 and a second locking groove 76 are formed on the circumference of the piston 56 at a distance from each other. These are located essentially in the area of ​​the piston 56 that extends through the first pressure chamber, which functions as a safety chamber 78. The first pressure chamber, which serves as a safety chamber 78, is sealed against the housing 32 by means of a closure 68. An O-ring 70 for the closure 68 is accommodated in the closure 68. Additionally, a spring-loaded locking pin 62 is accommodated in the housing 32 of the hydraulic actuator 30 in the area of ​​the first pressure chamber, which functions as a safety chamber 78. This pin is secured by a cover 64, which can, for example, be screwed into the housing 32 from the outside. The cover 64 actuates a locking spring 72, which acts on the locking pin 62.The locking pin 62 is permanently pressed upwards in a vertical direction by a corresponding spring force. When the safety chamber 78 is pressurized, the pressure acts downwards on the top of the locking pin 62. The dimensions of the locking pin 62 ensure that the force generated by the pressure at a pressure of approximately 3.0 bar is greater than the spring force acting on the locking pin 62, causing the locking pin 62 to be moved downwards. This unlocks the locking pin 62 and, consequently, the piston 56. Furthermore, the longitudinal section in Figure 3 shows that the first pressure chamber, which functions as the safety chamber 78, is pressurized via the first hydraulic connection 34, while the second pressure chamber, which serves as the working chamber 80, can be pressurized with fluid via the second hydraulic connection 36.The second pressure chamber, which serves as working chamber 80, is furthermore sealed opposite the pressure plate 58 by the plate 52. The plate 52, in turn, is fixed in the housing 32 of the hydraulic actuator 30 by means of the retaining ring 38. The plate 52 is also sealed against the housing 32 by an O-ring 50. The same applies to the plate 52, which seals the second pressure chamber, which serves as working chamber 80, by means of an O-ring 54 embedded in its circumference.

[0053] Figure 4 shows the hydraulic actuator 30 in longitudinal section in a parking position 102. In this parking position 102, the parking lock 10 is engaged, and the vehicle is in a parking position 102. The profiles of a cone stroke 100, a pressure profile 108 in the safety chamber 78, and a pressure profile 114 in the working chamber 80 shown in Figure 4.1 correspond to the position of the individual components of the hydraulic actuator 30 according to Figure 4.

[0054] As shown in Figure 4, in the parked position 102, the first pressure chamber, which serves as safety chamber 78, and the second pressure chamber, which serves as working chamber 80, are depressurized. In the parked position 102, the piston 56 is positioned at its maximum extension 104 with respect to its cone stroke 100. In this case, the spring force transmitted to the plate 48 is applied by the first compression spring 40. Due to the lack of pressurization, no hydraulic force is effective inside the hydraulic actuator 30. In the position of the piston 56 shown in Figure 4, its longitudinal movement is secured by the locking pin 62, which is engaged in the first locking groove 74; that is, the parked position 102 is locked.

[0055] According to Figure 4.1, the cone stroke 100 assumes its maximum extension travel 104. For the sake of completeness, a zero travel of the piston 56 is designated by reference numeral 106. According to Figure 4.1, both the first pressure chamber, which serves as a safety chamber 78, and the second pressure chamber, which serves as a working chamber 80, are depressurized. The pressure profiles 108 and 114 shown in Figure 4.1 each assume their minimum values ​​(see positions 112, 118).

[0056] Starting from the locked park position 102 as shown in Figures 4 and 4.1, the piston 56 is first unlocked as shown in Figures 5 and 5.1. For this purpose, the locking pin 62 extends from the first locking groove 74. This allows the piston 56 to move towards the closure 68 when the second pressure chamber, which serves as the working chamber 80, is pressurized. However, in the state shown in Figure 5, the second pressure chamber, which serves as the working chamber 80, is not yet pressurized with fluid via the second hydraulic connection 36, so that the piston 56 remains in the park position 102 via the first compression spring 40 in Figure 5 (see also the curves in Figure 5.1).

[0057] As shown in Figure 5.1, when the locking pin 62 is disengaged 120, the cone stroke 100 remains at its maximum value 104, whereas the pressure in the second pressure chamber, which serves as a safety chamber 78, rises via the first hydraulic connection 34 to the low-pressure level on the order of less than 3.0 bar, preferably 2.8 bar. According to the illustration in Figure 5.1, the pressure level in the second pressure chamber, which serves as a working chamber 80, remains at a pressure minimum 118, according to the pressure curve 114.

[0058] Figures 6 and 6.1 show that the working pressure is built up in the second pressure chamber, which serves as the working chamber 80, via the second hydraulic connection 36. Due to the pressure build-up in the second pressure chamber, which serves as the working chamber 80, the pressure plate 58 moves towards the closure 68 due to the effect of the hydraulic force Fhydr. The hydraulic force Fhydr acting on the pressure plate 58 of the piston 56 is greater than the spring force generated by the first compression spring 40. This compresses the spring, and the cone stroke 100 assumes its minimum value, i.e., a value corresponding to a zero travel 106. Simultaneously, the piston 56 moves within the housing 32 such that the second locking groove 76 is now positioned opposite the locking pin 62, which has retracted into the housing 32 of the hydraulic actuator 30. Figure 6.Figure 1 shows that in this case, the cone stroke 100 describes a zero path 106, and the pressure rises to a pressure maximum 110 in the first pressure chamber, which serves as a safety chamber 78, according to the pressure profile 108. The same applies to the pressure profile 114 in the second pressure chamber, which serves as a working chamber 80.

[0059] Starting from the state shown in Figure 6, the locking pin 62 is now triggered to engage. According to the longitudinal section in Figure 6, it moves into the second locking groove 76 of the piston 56, which is opposite the locking pin 62. This blocks the piston's longitudinal movement. The pressure in the first pressure chamber, which serves as the safety chamber 76, reaches its minimum pressure 112, while the pressure level within the second pressure chamber, which serves as the working chamber 80, is maintained via the second hydraulic connection 36. The piston 56, or rather its plate 48, remains in this locked position, which is established by the locking pin 62 moving into the second locking groove 76. This achieves an unlocked position 126, as shown in Figure 8, and ensures its maintenance.

[0060] As can be seen from the illustrations in Figures 8 and 8.1, starting from the state shown in Figure 7, pressure relief of the second pressure chamber, which functions as working chamber 80, now takes place via the second hydraulic connection 36. The position of all components of the hydraulic actuator 30 shown in Figure 8, corresponding to an unlocking position 126 of the parking lock 10, shows that in the unlocking position 126 of the parking lock 10 shown in Figure 6, both pressure chambers, namely the safety chamber 78 and the working chamber 80, are depressurized, the piston 56 is blocked in the direction of movement by the locking pin 62, which is inserted into the second locking groove 76, and the unlocking position 126 of the parking lock 10 is maintained.

[0061] Corresponding to the positions of the components involved according to Figure 8 in the unlocking position 126, Figure 8.1 shows that in the unlocking position 126 of the parking lock 10, the cone stroke 100 assumes its value corresponding to a zero travel 106, and the pressures in the safety chamber 78 and the working chamber 80 reach their respective minimum pressures 112 and 118, respectively. In this case, the parking lock 10 is unlocked, and the vehicle, preferably an electrically powered vehicle, is ready to drive. The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, a multitude of modifications are possible within the scope specified by the claims, which are within the bounds of what is considered skilled in the art.

Claims

Claims 1. Parking lock (10) of a fluid-cooled e-axle module (1) which has at least one conveying unit (5) circulating a cooling fluid which is operated at a low pressure level, characterized in that the parking lock (10) is associated with a hydraulic actuator (30) which is operated at a low pressure level of less than 3 bar.

2. Parking lock (10) according to claim 1, characterized in that the hydraulic actuator (30) has a first pressure chamber, which is a safety chamber (78), and a second pressure chamber, which serves as a working chamber (80).

3. Parking lock (10) according to claims 1 and 2, characterized in that the hydraulic actuator (30) has a piston (56) which receives a pressure plate (58) which is received within the second pressure chamber which serves as a working chamber (80).

4. Parking lock (10) according to claims 1 to 3, characterized in that the piston (56) has a first locking groove (74) and a second locking groove (76) which are located in a region of the piston (56) which is enclosed by the first pressure chamber which serves as a safety chamber (78).

5. Parking lock (10) according to claims 1 to 4, characterized in that a spring-loaded locking pin (62) is received in the housing (32) of the hydraulic actuator (30), which is associated with the locking grooves (74, 76).

6. Parking lock (10) according to claims 1 to 5, characterized in that in a parking position (102) a first compression spring (40) holds the piston (56) extended by a maximum extension distance (104).

7. Parking lock (10) according to claim 6, characterized in that in the parking position (102) the second pressure chamber, which serves as a working chamber (80), is depressurized.

8. Parking lock (10) according to claims 6 and 7, characterized in that in the parking position (102) the piston (56) is locked in the first locking groove (74) by means of the locking pin (62).

9. Parking lock (10) according to claims 1 to 8, characterized in that an unlocking position (126) of the parking lock (10) is achieved by disengaging (120) the locking pin (62) from the first locking groove (74) and pressurizing the first pressure chamber, which serves as a working chamber (80).

10. Parking lock (10) according to claim 9, characterized in that a pressure maximum (110) is generated in the second pressure chamber, which serves as a working chamber (80), which generates a hydraulic force Fnydr that exceeds a spring force Fs of the first compression spring (40).

11. Parking lock (10) according to claims 9 and 10, characterized in that in the unlocking position (126) of the parking lock (10) the locking pin (62) engages in a second locking groove (76) of the piston (56).

12. Use of the parking lock (10) according to one of claims 1 to 11 (12) of a fluid-cooled e-axle module in an electrically powered vehicle.

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