Parking lock system having a parking lock sensor and a locking sensor, and method for monitoring the parking lock system

Abstract

A parking lock system 1 is proposed having a parking lock wheel 7; a parking lock 2; an emergency unlocking device 17 which is operatively connected to the parking lock 2 in order to transfer the parking lock 2 in an emergency situation from an engaged position P_ein into a disengaged position P_aus; a parking lock actuator 15 which has two pistons 22, 23, wherein the first piston 22 can be subjected to an actuating force F1 in order to transfer it into the disengagement position P_aus, and the second piston 23 can be moved relative to the first piston 22 by means of the emergency unlocking device 17 in order to transfer it into the disengagement position P_aus; having a parking lock sensor 38 which is designed to detect the engagement position P_ein and the disengagement position P_aus and to provide same as sensor information; having a control unit 33, wherein the parking lock system 2 has a locking sensor 40 which is designed to detect an engaged and disengaged locking position V_ein, V_aus of the locking device and to provide same as further sensor information, wherein the control unit 33 is designed to distinguish, on the basis of the sensor information, between an engaged and disengaged state Z_ein, Z_aus of the parking lock 2 and an emergency unlocking state Z_not initiated by the emergency unlocking device 17.

Description

[0001] Parking lock system with a parking lock sensor and a locking sensor and method for monitoring the parking lock system

[0002] The invention relates to a parking lock system for an automatic transmission of a motor vehicle having the features of the preamble of claim 1. Furthermore, the invention relates to a method for monitoring the parking lock system.

[0003] Parking locks for automatic transmissions of vehicles are known which can be brought into operative connection with the transmission to secure the vehicle against rolling away when stationary. Such parking locks usually comprise a pawl pivoted on a pawl pin, which engages or disengages with a parking lock gear connected to the transmission output. To disengage the parking lock, a hydraulically actuated parking lock cylinder is provided, which has a piston whose movement is coupled to a locking element. When the parking lock is engaged, the locking element prevents the pawl from being pushed out of a tooth gap in the parking lock gear. To disengage the parking lock, a cylinder chamber of the parking lock cylinder is pressurized, whereby the locking element is actuated and the pawl is released.Furthermore, an emergency release is usually provided so that the locking pawl can be mechanically disengaged in the event of a failure of the hydraulic pressure supply.

[0004] The document DE 10 2018 203 166 A1 describes a parking lock, comprising a parking lock gear connected to a transmission shaft with a locking toothing, as well as a pivotably mounted locking pawl with a ratchet tooth, which engages in the locking toothing of the parking lock gear when the parking lock is engaged.Furthermore, the parking lock comprises a connecting rod which is movable to specify the switching position of the parking lock and has a locking element which, when the parking lock is engaged, causes the pawl to engage the locking teeth of the parking lock gear and, when the parking lock is engaged, prevents the pawl from being pushed out of the locking teeth of the parking lock gear, an insertion spring which acts on the connecting rod in the parking lock engagement direction, an actuator which acts on the connecting rod in the parking lock release direction, a position sensor for determining the current switching position of the parking lock, and an electromagnetically actuated locking device by means of which a piston of the actuator which can be pressurized to disengage the parking lock can be mechanically fixed depending on the situation either in a piston position assigned to the engaged state of the parking lock or in a piston position assigned to the disengaged state of the parking lock.In addition, the parking lock includes a system implemented in an electronic control unit by means of which the current switching position of the locking device can be determined by estimating the current inductance at the electromagnet.

[0005] The invention is based on the object of proposing a parking lock system of the type mentioned above, which is characterized by reliable status detection of the parking lock system.

[0006] This object is achieved by a parking lock system having the features of claim 1 and a method having the features of claim 10. Further embodiments and advantages according to the invention emerge from the corresponding subclaims as well as the following description and attached figures.

[0007] The subject of the invention is a parking lock system designed and / or suitable for an automatic transmission or electric axle of a motor vehicle. The parking lock system serves to lock and / or lock an axle, particularly when a vehicle is stationary, so that the vehicle is secured against rolling away.

[0008] For this purpose, the parking lock system comprises a parking lock gear and a parking lock, wherein the parking lock is engaged with the parking lock gear in an engaged position or locks the parking lock gear, and is disengaged or releases the parking lock gear in a disengaged position. In particular, the parking lock gear has locking teeth with tooth gaps. Preferably, the parking lock gear is connected in a rotationally fixed manner to a transmission shaft of a vehicle transmission, in particular an automatic transmission. The parking lock preferably comprises a pawl pivotably mounted on a pawl pin and having a pawl tooth which, in the engaged position of the parking lock, engages in a tooth gap of the locking teeth, thereby blocking the parking lock gear and transmission shaft against rotation.

[0009] Optionally, the parking lock can have a shift lever that can be rotated about a shift lever rotation axis to specify the shift position of the parking lock. The shift lever can be coupled in motion to a locking element spring-loaded in a parking lock engagement direction via a connecting rod articulated to the shift lever. The locking element causes the ratchet tooth to engage a tooth gap in the locking toothing when the parking lock is engaged and prevents the ratchet tooth from being pushed out of the tooth gap in the locking toothing when the parking lock is engaged.

[0010] Furthermore, the parking lock system comprises an emergency release device that is operatively connected to the parking lock and / or can be brought into operative connection in order to transfer the parking lock from the engaged position to the disengaged position in an emergency situation. In particular, the emergency release device is motion-coupled to the parking lock, preferably the gearshift lever, in such a way that the parking lock can be manually and / or mechanically disengaged or transferred from the engaged position to the disengaged position.

[0011] The parking lock system comprises a parking lock actuator having a first and a second piston. Preferably, the two pistons are arranged coaxially with respect to a main axis of the parking lock actuator and / or are arranged in an actuator housing of the parking lock actuator so as to be displaceable relative to one another in the axial direction. In other words, the two pistons are arranged one behind the other in the axial direction with respect to the main axis.

[0012] The first piston can be subjected to an actuating force to transfer the parking lock into the disengaged position. In particular, the actuating force is applied to the first piston in a parking lock disengagement direction. The actuating force can be generated hydraulically, pneumatically, or electromechanically. For example, a compressive force is applied to the first piston as the actuating force by hydraulic pressure. Particularly preferably, the parking lock actuator has an insert spring whose spring force acts on the first and second pistons in a parking lock engagement direction. To disengage the parking lock, the first piston is subjected to the actuating force, whereby the first and second pistons are displaced against the spring force of the insert spring in the axial direction relative to the main axis, preferably in the parking lock disengagement direction.To engage the parking lock, however, the actuating force is reduced, whereby the first and second pistons are displaced axially in opposite directions relative to the main axis, preferably in the parking lock engagement direction, by the spring force of the insert spring. The insert spring can be designed as a compression spring that is clamped axially between the second piston and the actuator housing.

[0013] The second piston is movable relative to the first piston by the emergency release device to transfer the parking lock into the disengaged position. Preferably, the second piston is directly coupled in motion to the parking lock and / or the first piston is operatively connected to the parking lock via the second piston. Particularly preferably, the second piston is coupled in motion to the gearshift lever in such a way that an axial movement of the second piston causes the gearshift lever to rotate about the gearshift lever's axis of rotation and vice versa. This enables the second piston to be axially displaced when the emergency release device is actuated without the first piston leaving its locked piston position corresponding to the engaged position.

[0014] The parking lock actuator also has a locking device which is designed and / or suitable for locking the first piston in a piston position associated with the engaged position and / or the disengaged position. The locking device preferably has two positions, preferably an engaged and a disengaged locking position. Here, "engaged" and "disengaged" always refer to the corresponding piston position of the first piston. In other words, in the engaged locking position, the first piston is locked in the engaged position, and in the disengaged locking position, the first piston is locked in the disengaged position. Optionally, the locking device has one or more intermediate positions and / or an engaged and a disengaged unlocking position. The locking device is preferably designed as an electromechanical locking mechanism and / or is electrically actuable.

[0015] The parking lock system comprises a parking lock sensor configured to detect the engaged and disengaged positions of the parking lock and to provide this information as sensor information. The parking lock sensor is preferably configured as a non-contact position sensor capable of detecting whether the parking lock, in particular the pawl and / or the shift lever, is in a pawl or lever position associated with the engaged or disengaged position. The parking lock sensor preferably comprises a sensor transmitter arranged on the pawl or the shift lever, which can be detected by a sensor receiver.

[0016] The parking lock system further comprises a control unit configured to distinguish between an engaged and a disengaged state of the parking lock based on the sensor information. In particular, the control unit serves to monitor and control the parking lock system, in particular the parking lock actuator. For this purpose, a control algorithm can be stored in the control unit, via which the parking lock actuator can be controlled depending on the vehicle operation. In addition, the control unit has a diagnostic algorithm that can detect and document possible errors in the control. In particular, the position sensor transmits the currently measured switching position of the parking lock to the control unit as sensor information in real time. The position sensor is preferably connected to the control unit by signaling, for example via an electrical line.The control unit can be designed as an electronic control unit.

[0017] Within the scope of the invention, it is proposed that the parking lock system have a locking sensor which is designed to detect the engaged locking position and the disengaged locking position of the locking device and to provide this as additional sensor information. The control unit is designed to distinguish, based on the additional sensor information, between an emergency release state initiated by the emergency release device in addition to the disengaged and engaged states. The control unit can evaluate and further process the sensor information and the additional sensor information using evaluation logic. Preferably, the control unit is designed to distinguish, based on the sensor information and the additional sensor information, between a switching state of the parking lock initiated by the parking lock actuator and the emergency release device, or a change in the switching state.Optionally, the control unit is designed to detect a faulty switching state of the parking lock and / or a faulty change in the switching state based on the sensor information and the additional sensor information. Optionally, the control unit can additionally have an error memory in which the faulty switching state of the parking lock and / or the faulty change in the switching state can be stored for query during repair and / or maintenance. Preferably, the switching states and / or state changes can be taken into account by the control algorithm and / or the diagnostic algorithm. Optionally, the engaged state, the disengaged state, and the emergency release state can be provided to a visual and / or acoustic display module, whereby a driver can be informed of the actual switching state of the parking lock.Preferably, the locking sensor is connected to the control unit in terms of signal technology, for example via another electrical line.

[0018] The invention is based on the finding that the parking lock can be actuated both via the emergency release device and via the parking lock actuator. In this case, manipulation of the parking lock via the emergency release device leads to “false positives” in the diagnostic algorithm implemented in the control unit. For example, an error message “Parking lock erroneously leaves the engaged position” is output if the emergency release device moves the parking lock into the disengaged position. In addition, an error message “Parking lock erroneously remains in the disengaged position” is output if the emergency release device prevents the parking lock from being moved into the engaged position. The known parking lock sensors do not differentiate between an actual error and control via the emergency release device. By using the additional sensor information from the locking sensor, a reduction orElimination of "false positives" is made possible. By additionally considering the engaged and disengaged locking position, an actual actuation by the parking lock actuator can be taken into account in addition to the actual switching state of the parking lock, which at least allows the disengagement of the parking lock by the emergency release device to be reliably detected. Thus, a parking lock system is proposed that is characterized by reliable state detection.

[0019] In a specific embodiment, the locking sensor is designed as a position sensor configured to detect the engaged locking position and the disengaged locking position based on a position change of the locking device. Preferably, the locking sensor is designed as a non-contact measuring position sensor, with which it can be detected whether the first piston is locked in a piston position associated with the engaged position or the disengaged position. In particular, the locking device has a locking mechanism that switches between the engaged and disengaged locking positions through a position change detectable by the position sensor. The position change can occur, for example, through a rotational movement and / or linear movement, preferably relative to the main axis.A locking sensor is thus proposed which can clearly distinguish between two different locking positions in a simple and reliable manner.

[0020] In a further embodiment, the locking device comprises a locking rod which is displaceable in the axial direction relative to a main axis of the parking lock actuator between the engaged locking position and the disengaged locking position, wherein the locking rod at least indirectly locks the first piston in the engaged locking position and in the disengaged locking position. In particular, one or more locking elements can be controlled via the locking rod into a corresponding locking contour of the first piston in order to lock the first piston in the axial direction relative to the main axis in the engaged and disengaged piston positions. Preferably, the locking rod is arranged coaxially and / or concentrically to the first piston with respect to the main axis.Particularly preferably, the locking rod is arranged to be movable radially within the first piston. By using a locking device that locks the first piston in both the engaged and disengaged piston positions, the current piston position of the first piston can always be clearly determined based on the locking position.

[0021] In one specific embodiment, the locking sensor is designed to detect an axial position of the locking rod. In particular, the locking rod assumes two different axial positions in the engaged and deployed locking positions, which can be detected by the locking sensor. Preferably, the two locking positions are each defined by an axial end position. Optionally, the locking rod can assume an intermediate position in an unlocked position, which can be detected by the locking sensor. In particular, the locking rod assumes two different intermediate positions in an engaged and deployed unlocked position, which can be detected by the locking sensor. In particular, the locking sensor is designed as the position sensor for this purpose.A locking device is thus proposed which is characterized by clearly assignable locking and unlocking positions.

[0022] In a further specific embodiment, the locking sensor comprises a sensor receiver fixed to the parking lock actuator and a sensor transmitter coupled to the locking rod, which can be detected by the sensor receiver. In particular, the sensor transmitter and the sensor receiver can interact inductively and / or capacitively, preferably without contact. For example, the sensor transmitter is designed as a magnet and the sensor receiver as a Hall sensor. Thus, a particularly robust locking sensor is proposed. Furthermore, by evaluating the field strength, the current position of the locking rod can be clearly determined for each axial position.

[0023] In a further specific implementation, the locking device comprises an electromagnet. In particular, the electromagnet serves for the electromagnetic actuation of the locking device. When the electromagnet is energized, the locking device is arranged in one locking position, in particular the disengaged locking position, and when the electromagnet is deenergized, it is arranged in the other locking position, in particular the engaged locking position. In particular, the locking device, in particular the locking rod, can be actuated via the electromagnet such that it is energized to lock the first piston in one of the two locking positions and is not energized in the other locking position.Specifically, this means that the first piston is locked when de-energized in the engaged piston position and / or unlocked when energized, and is unlocked when de-energized and / or locked when energized in the disengaged piston position. In particular, the locking rod is automatically held in the locked position when the piston is engaged and moved into the engaged unlocked position when energized to the electromagnet and / or is held in the disengaged locking position when the electromagnet is energized in the disengaged piston position and automatically moved into the disengaged unlocked position when the power supply is interrupted. Thus, a locking device is proposed which is characterized by secure engagement and locking of the parking lock in the event of an electrical failure. In addition, the emergency release device can ensure disengagement at any time in order to be able to move the vehicle in the event of a fault.

[0024] In a further development, the locking device comprises a locking spring which, when the electromagnet is de-energized, holds the locking rod in one of the locking positions, in particular the engaged locking position, and / or automatically transfers it into one of the locking positions, in particular the engaged locking position. Depending on the piston position, the electromagnet must be selectively energized to lock or unlock the first piston, whereby the locking rod is moved in the axial direction relative to the main axis against the spring force of the locking spring. The locking spring can be designed as a compression spring which is clamped axially between the locking rod and the actuator housing. Preferably, the spring force of the locking spring acts on the locking rod in one of the locking positions, in particular the engaged locking position.The locking spring ensures secure actuation of the locking device in either piston position. Furthermore, it is easy to distinguish between the two locking positions, as one is engaged mechanically and the other electrically or electromagnetically.

[0025] In a further implementation, the control unit is configured to consider the energized and / or de-energized state of the electromagnet when distinguishing between the engaged state, the disengaged state, and the emergency release state. In other words, the control unit is configured to consider the electromagnet's electrical current as additional information when evaluating the sensor information. In particular, the control unit is connected to the electromagnet via electrical and / or signaling for this purpose. Specifically, the control unit has a circuit for regulating the electromagnet's current. This allows for redundant and reliable determination of the states in a simple manner.

[0026] In an alternative or supplementary implementation, the control unit is designed to take into account a reference variable for the actuating force when distinguishing between the engaged state, the disengaged state, and the emergency release state. In other words, the control unit is designed to take into account the reference variable of the actuating force as additional information when evaluating the sensor information. The reference variable of the actuating force can be formed by an electric current during an electromechanical actuation of the first piston, or by a hydraulic pressure during a hydraulic actuation of the first piston, or by a pneumatic pressure during a pneumatic actuation of the first piston. In particular, the control unit is connected electrically and / or by signaling to the parking lock actuator and / or a corresponding hydraulic or pneumatic actuation system.This makes it easy to achieve redundant and reliable determination of the states.

[0027] Another object of the invention relates to a method for monitoring the parking lock system as already described above, in which:

[0028] - the engagement and disengagement positions of the parking lock are recorded and provided as sensor information;

[0029] - the engaged locking position and the disengaged locking position are recorded and provided as additional sensor information;

[0030] - based on the sensor information and the further sensor information, a distinction is made between the insertion state and the removal state and the emergency release state.

[0031] The description of the method steps is not intended to specify a sequence for their execution. Rather, individual steps can be interchanged, repeated, or omitted. The control unit is preferably configured to carry out the method. In particular, the parking lock and the locking device are monitored in real time so that, in addition to the states, a change in the parking lock position and the locking position can also be detected. Optionally, one or more intermediate positions between the engaged position and the disengaged position and / or between the engaged locking position and the disengaged locking position can also be detected and provided as additional sensor information. In particular, the parking lock is moved into the disengaged position during normal vehicle operation by the actuating force being applied to the first piston.In particular, in an emergency situation, the parking lock is transferred to the disengaged position by moving the second piston independently of the first piston by the emergency release device.

[0032] In a specific implementation, the engaged state of the parking lock is detected when the engaged position is detected and the engaged locking position is detected; the disengaged state of the parking lock is detected when the disengaged position is detected and the disengaged locking position is detected; and the emergency release state is detected when the disengaged position is detected and the engaged locking position is detected. This results in reliable state detection of the engaged, disengaged, and emergency release states.

[0033] In a first emergency release scenario, it is provided that, starting from the engaged state in which the parking lock is in the engaged position and the locking device is in the locked position and the control unit is switched off, the parking lock is transferred to the disengaged position by the emergency release device; the control unit is switched on; and the disengaged position and the engaged locking position are detected, with the emergency release state being recognized based on the sensor information. In simple terms, the emergency release device is engaged when the control unit is switched off, with the emergency release state being recognized if the position of the parking lock does not match the associated locking position. This can prevent the control unit from being overridden if the parking lock is disengaged when the control unit is switched off.

[0034] In a second emergency release scenario, it is provided that, starting from the engaged state in which the parking lock is in the engaged position and the locking device is in the engaged locking position and the control unit is switched on, the parking lock is transferred to the disengaged position by the emergency release device; and a change from the engaged position to the disengaged position and no change in the locking position is detected, wherein the emergency release state is recognized based on the sensor information. In simple terms, the emergency release device is engaged while the control unit is switched on, wherein the emergency release state is recognized when the position of the parking lock deviates from the associated locking position. This enables real-time monitoring of the parking lock system, which detects the manual emergency release and recognizes it as such.In a further development, it is provided that the first piston is transferred to the disengaged piston position when the actuating force is increased, and is automatically transferred to the engaged piston position when the actuating force is reduced. In this case, the disengaged state is reliably detected if the actuating force is also increased and / or has been increased. In particular, the disengaged state is reliably detected if the disengaged position or a transfer to the disengaged position is detected and the disengaged locking position or a transfer to the disengaged locking position is detected and, in addition, the actuating force is increased and / or has been increased. In simplified terms, the disengaged position can be detected as “normally designed” if the disengaged position and the disengaged locking position are detected and, in addition, an increase in the actuating force has taken place.

[0035] Furthermore, it is provided that the insertion state and the emergency release state are reliably detected if the hydraulic pressure is also reduced. In particular, the insertion state is reliably detected when the insertion position or a transition to the insertion position is detected and the engaged locking position or a transition to the engaged locking position is detected and in addition the actuating force is reduced and / or has been reduced. In simplified terms, the insertion position can be detected as “normally inserted” if the insertion position and the engaged locking position are detected and in addition a reduction in the actuating force has taken place. In particular, the emergency release state is reliably detected when the release position or a transition to the release position is detected and the engaged locking position is detected and in addition the actuating force is reduced.In particular, the actuation force can be determined based on the reference value. This enables reliable status or error detection.

[0036] Alternatively or optionally in addition, it is provided that the locking device is locked without current in the engaged locking position and is locked with current in the disengaged locking position. In this case, it is provided that the disengaged state is reliably detected if the locking device is also energized. In particular, the disengaged state is reliably detected if the disengaged position or a transition to the disengaged position is detected and the disengaged locking position or a transition to the disengaged locking position is detected and additionally the electromagnet is energized. In simplified terms, the disengaged position can be detected as "normally designed" if the disengaged position and the disengaged locking position are detected and additionally the electromagnet is energized.

[0037] Furthermore, it is provided that the insertion state and the emergency release state are reliably detected when the locking device is also de-energized. In particular, the insertion state is reliably detected when the insertion position or a transition to the insertion position is detected and the engaged locking position or a transition to the engaged locking position is detected and additionally no current is supplied to the electromagnet. In simplified terms, the insertion position can be detected as “normally inserted” if the insertion position and the engaged locking position are detected and additionally the electromagnet is de-energized. In particular, the emergency release state is reliably detected when the release position or a transition to the release position is detected and the engaged locking position is detected and additionally no current is supplied to the electromagnet.

[0038] Further features, advantages, and effects of the invention will become apparent from the following description of preferred embodiments of the invention. These show:

[0039] Fig. 1 is a schematic representation of a parking lock system with a parking lock sensor and a locking sensor;

[0040] Fig. 2 is a schematic representation of a parking lock actuator in an engaged state of the parking lock;

[0041] Fig. 3 shows the parking lock actuator in the same representation as shown in Fig. 2 in a disengaged state of the parking lock; Fig. 4 shows a method for monitoring the parking lock system using a state diagram.

[0042] Figure 1 shows a parking lock system 1 for an automatic transmission of a motor vehicle as one exemplary embodiment of the invention. The parking lock system 1 has the function of securing the motor vehicle against rolling away when stationary. For this purpose, the parking lock system 1 comprises a parking lock 2, which has a pawl 4 pivotably mounted on a pawl pin 3 and provided with a pawl tooth 5. In an engaged position P_on, as shown, the pawl tooth 5 is engaged with the tooth gap 6 of a parking lock gear 7 connected to a transmission shaft (not shown) of the automatic transmission, and is disengaged in a disengaged position P_off, not shown.

[0043] Furthermore, the parking lock 2 comprises a locking element 10, which is axially displaceable on a connecting rod 8 and spring-loaded via a spring element 9. In the inserted position P_ein, the locking element 10 is clamped between the pawl 4 and a guide plate (not shown here) fixed to the housing to prevent the pawl tooth 5 from being pushed out of the corresponding tooth gap 6 of the parking lock gear 7. For example, the locking element 6 is designed as a locking cone or, alternatively, as a roller element.

[0044] The end of the connecting rod 8 facing away from the locking element 10 is pivotally connected to a shift lever 12 rotatably mounted on the pawl pin 3, so that the pivot axes of the pawl 4 and the shift lever 12 are identical. To engage and disengage the parking lock 2, the shift lever 12 has a driver 13, which is motion-coupled to a piston rod 14 of a hydraulically actuated parking lock actuator 15, shown only schematically here, by means of which the shift position of the parking lock 2 can be specified. The piston rod 14 is arranged to be axially displaceable in an actuator housing 16 of the parking lock actuator 15, wherein the parking lock actuator 15 is subjected to an actuating force F1 resulting from a hydraulic pressure in order to disengage the parking lock 2 and the piston rod 14 is thereby moved in a parking lock disengagement direction 101.

[0045] The parking lock system 1 has an emergency release device 17, by means of which the parking lock 2 can be mechanically and / or manually moved from the engaged position P_on to the disengaged position P_off in the event of a failure of the hydraulic and / or electrical control of the parking lock actuator 15. For this purpose, the emergency release device 17 is mechanically coupled to the piston rod 14 via an emergency lever 19 pivotably mounted about a pivot pin 18.

[0046] The emergency lever 19 has a leg 20 which, when the emergency release device 17 is actuated, mechanically acts directly on the piston rod 14 in the parking lock disengagement direction 101, so that the piston rod 14 rotates in the parking lock disengagement direction 101 and the shift lever 12 thus rotates on the pawl pin 3 in the direction of rotation intended for disengaging the parking lock 2. An axial movement of the piston rod 14 always causes a rotation of the shift lever 12 and the emergency lever 19 about the respective axis of rotation. On the other hand, a rotation of the shift lever 12 or the emergency lever 19 about the respective axis of rotation always also causes an axial movement of the piston rod 14. The emergency release device 17 also has a return spring 21, which applies a restoring force to the emergency lever 19, returning it to its initial position.

[0047] As shown in Figures 2 and 3, the parking lock actuator 15 has a first piston 22 and a second piston 23, which are arranged axially displaceably on a common main axis 100 in the actuator housing 16, wherein only the first piston 22 can be subjected to hydraulic pressure to disengage the parking lock 2. For this purpose, the first piston 22, together with the actuator housing 16, delimits a pressure chamber 24, which is connected to a hydraulic system (not shown in detail) via a pressure connection 25. The second piston 23 is arranged outside the pressure chamber 24 and is axially supported on the first piston 22. The piston rod 14 is fixedly connected to the second piston 23, so that a movement of the piston rod 14 always causes a movement of the second piston 23.When pressure is applied, the first piston 22 displaces the second piston 23 in the axial direction relative to the main axis 100, counter to a spring force F2 of an insert spring 26, in the parking lock disengagement direction 101. The insert spring 26 is designed as a compression spring clamped axially between the second piston 23 and the actuator housing 16, which concentrically encloses the piston rod 14 when viewed axially and applies the spring force F2 to the second piston 23 in a parking lock engagement direction 102 opposite the parking lock disengagement direction 101. Thus, the parking lock 2 is engaged essentially by the spring force F2 of the insert spring 9, whereas the parking lock is disengaged essentially by the hydraulic pressure force applied to the first piston 22 or the actuating force F1 against the spring force F2 of the insert spring 26.

[0048] Furthermore, the parking lock actuator 15 has a locking device 27 which is arranged within the actuator housing 16 - here, for example, centrally within the first piston 22 - and can be electromagnetically actuated by an electromagnet 28 arranged on the actuator housing 16 such that the locking device 27 mechanically locks the first piston 22 in an engaged piston position K_ein assigned to the engagement position P_ein and in a disengaged piston position K_aus assigned to the disengagement state P_aus.

[0049] For this purpose, the locking device 27 has axially spaced locking elements 29a, 29b, which can be brought into engagement with a locking contour 30 formed on the first piston 22 in order to fix the first piston 22 in the axial direction. For example, the locking elements 29a, 29b are formed by a plurality of circumferentially arranged balls, which can be radially extended or retracted via a locking rod 31 that is displaceable in the axial direction relative to the main axis 100 between an engaged locking position V_on and a disengaged locking position V_off. The engaged locking position V_on is to be understood as a locking position assigned to the engaged piston position K_on, and the disengaged locking position V_off is to be understood as a locking position assigned to the disengaged piston position K_off.The locking device 27 is thus configured to lock the first piston 22 both in the engaged piston position K_on and in the disengaged piston position K_off.

[0050] Furthermore, the locking device 27 has a locking spring 32, which applies a spring force F3 to the locking rod 31 axially in the direction of the engaged locking position V_on. The locking spring 32 is designed as a compression spring clamped axially between the locking rod 31 and the electromagnet 28, which concentrically surrounds the locking rod 31 when viewed axially and displaces the locking rod 31 in the direction of the engaged locking position V_on when the electromagnet 28 is de-energized.

[0051] As shown in Figure 2, the first piston 22 is locked in the engaged piston position K_on when the electromagnet 28 is not energized. To release the locking in the engaged piston position K_on, the electromagnet 28 must be energized. Thus, locking of the first piston 22 in the engaged piston position K_on is achieved essentially by the spring force F3 of the locking spring 32, whereas unlocking is achieved essentially by the magnetic force applied to the locking rod 31 against the spring force F3 of the locking spring 32.

[0052] As shown in Figure 3, the second piston 22 is locked in the disengaged piston position K_off when the electromagnet 31 is energized, whereby the power supply to the electromagnet 28 must be interrupted to release the lock in the disengaged piston position K_off. Thus, unlocking of the first piston 22 in the disengaged piston position K_off occurs essentially by the spring force F3 of the locking spring 32, whereas locking occurs essentially by the magnetic force applied to the locking rod 31 against the spring force F3 of the locking spring 32. When the parking lock 2 is engaged, the relevant components of the parking lock actuator 15 are in their respective positions as shown in Figure 2.In order to transfer the parking lock 2 from the engaged position P_on to the disengaged position P_off, the electromagnet 28 is first energized, with the result that the locking rod 31 is moved into an unlocked position against the spring force F3 and releases the first piston 22. At about the same time, the previously depressurized pressure chamber 24 is pressurized, with the result that the first piston 22 moves axially in the parking lock disengagement direction 101 due to the resulting actuating force F1 against the spring force F2 of the engagement spring 26, taking the second piston 23 with it until both pistons 22, 23 reach the disengaged piston position K_off and the parking lock 2 is transferred to the disengaged position P_off. By energizing the electromagnet 28, the locking rod 31 is moved further into the designed locking position V_off against the spring force F3 and the first piston 22 is locked.This protects the parking lock system 1 against unintentional engagement of the parking lock 2, which could occur, for example, if the pressure level is insufficient in a given situation or if there is a hydraulic defect in the pressure supply to the pressure chamber 24. The parking lock 2 is now in a disengaged state, with all components of the parking lock actuator 15 now in the position shown in Figure 3.

[0053] In the event of a failure of the hydraulic and electrical system, the actuating force F1 or the system pressure is reduced and the first piston 22 is automatically moved into the engaged piston position K_on and locked. The parking lock 2 is again in the engaged state. In this case, a mechanical disengagement of the parking lock 2 must still be possible, which is made possible by the second piston 23, which is movable relative to the first piston 22. In the event of an actuation of the emergency release device 17, the second piston 23 is axially displaced by the emergency lever 19 into the disengaged piston position K_off and the first piston 22 remains locked in the engaged piston position K_on and is thus blocked against axial movement. The parking lock 2 is now in an emergency release state, not shown. This gives the driver the option of disengaging the parking lock 2 themselves in order to bring the vehicle into a rolling state.For electrically controlling the electromagnet 28 and hydraulically controlling the pressure chamber 24, the parking lock system 1 has an electronic control unit 33, as schematically shown in Figure 1. For example, the electronic control unit 33 can be electrically connected to the electromagnet 28 via an electrical line 34 and to a hydraulic system 36 (indicated only schematically) via another electrical line 35, which in turn is fluidly connected to the pressure chamber 24 via a hydraulic line 37. For example, a control algorithm is implemented in the control unit 33, which assumes the control task of the parking lock actuator 15.

[0054] Furthermore, the parking lock system 1 has a schematically illustrated parking lock sensor 38, which is designed to detect the engagement position P_on and the disengagement position P_off of the parking lock 2 and to provide it as sensor information to the control unit 33. The parking lock sensor 38 is designed as a preferably inductively operating position sensor, which, for example, detects a lever position of the gearshift lever 12 associated with the engagement position P_on and the disengagement position P_off. The parking lock sensor 38 is operatively connected to the gearshift lever 12 and is signal-connected to the control unit 33 via a signal line 39.

[0055] In order to reliably distinguish between the engaged state, the disengaged state, and the emergency release state, the parking lock system 1 additionally has a locking sensor 40, which is designed to detect the engaged locking position V_on and the disengaged locking position V_off of the locking device 27 and to provide this information to the control unit 33 as additional sensor information. The locking sensor 40 is designed as a preferably inductively operating position sensor, which detects, for example, an axial position of the locking rod 31. For this purpose, the locking sensor 40 is operatively connected to the locking rod 31 and is signal-connected to the control unit 33 via a further signal line 41.

[0056] As shown in Figures 2 and 3, the locking sensor 40 has a sensor transmitter 42, e.g., a magnet, which is motion-coupled to the locking rod 31, and a sensor receiver 43, e.g., a Hall sensor, which is attached to the actuator housing 16 and interacts with the sensor transmitter 42 and is connected to the control unit 33 via the additional signal line 41 (not shown here). The signal transmitter 42 and the signal receiver 43 communicate with each other, for example, without contact.

[0057] The control unit 33 is configured to evaluate or correlate the sensor information from the position sensor 38 and the locking sensor 40 in order to distinguish between the engaged state, the disengaged state, and the emergency release state of the parking lock 2 based on the sensor information. For this purpose, an evaluation logic can be implemented, for example, in the electronic control unit 33. Optionally, a current supply state of the electromagnet 28 and / or a reference variable of the actuating force F1, such as the hydraulic pressure, can also be taken into account when evaluating the sensor information.

[0058] Figure 4 uses a state diagram to show a method for monitoring the parking lock system 1. Starting from an initial state Z_0, in which the control unit 23 is started or already switched on, a distinction can be made between the disengagement state Z_off, the engagement state Z_on, and the emergency release state Z_not. Furthermore, a change to the disengagement state Z_off, the engagement state Z_on, and the emergency release state Z_not can be detected when the control unit 23 is switched on. For this purpose, the current parking lock position P_on, P_off and the current locking position V_on, V_off are recorded in real time and provided to the control unit 23.

[0059] The disengagement state Z_off is detected when the engagement position P_off and the engaged locking position V_off are detected. Optionally, the disengagement state Z_off is detected if, in addition, the electromagnet 28 is energized and / or the hydraulic pressure is increased or greater than a stored threshold value. Accordingly, a change to the disengagement state Z_off is detected when a change to the disengagement position P_off or a corresponding intermediate position of the pawl 4 is detected and a change to the disengaged locking position V_off or a corresponding intermediate position of the locking rod 31 is detected. Optionally, a change to the disengagement state Z_off is detected if, in addition, the electromagnet 28 is energized and / or the hydraulic pressure is increased or the stored threshold value is exceeded.

[0060] An engagement state Z_on is detected when the engagement position P_on and the engaged locking position V_on are detected. Optionally, the engagement state Z_on is detected if, in addition, the electromagnet 28 is not energized and / or the hydraulic pressure is reduced or is less than a stored threshold value. Accordingly, a change to the engagement state Z_on is detected when a change to the engagement position P_on or a corresponding intermediate position of the pawl 4 is detected and a change to the engaged locking position V_on or a corresponding intermediate position of the locking rod 31 is detected. Optionally, a change to the engagement state Z_off is detected if, in addition, the electromagnet 28 is not energized and / or the hydraulic pressure is reduced or the stored threshold value is undershot.

[0061] An emergency release state Z_not is detected when the disengaged position P_off and the engaged locking position V_on are detected. Optionally, the emergency release state Z_not is detected if, in addition, the electromagnet 28 is de-energized and / or the hydraulic pressure is reduced or less than a stored threshold value. Accordingly, a change to the emergency release state Z_not is detected if a change to the disengaged position P_off or a corresponding intermediate position of the locking pawl 4 is detected and no change to the engaged locking position V_on is detected. Optionally, a change to the emergency release state Z_not is detected if, in addition, the electromagnet 28 is de-energized and / or the hydraulic pressure is reduced or less than the stored threshold value. Reference symbol

[0062] Parking lock system

[0063] Parking lock

[0064] latch bolt

[0065] pawl

[0066] Jack tooth

[0067] Gap between teeth

[0068] Parking lock gear

[0069] connecting rod

[0070] spring element

[0071] Locking element

[0072] gearshift lever

[0073] Driver

[0074] piston rod

[0075] Parking lock actuator

[0076] Actuator housing

[0077] Emergency release device

[0078] pivot pin

[0079] emergency lever

[0080] leg

[0081] Return spring first piston second piston

[0082] printing room

[0083] Pressure connection

[0084] Insert spring

[0085] Locking device

[0086] Electromagnet a, b locking elements

[0087] Locking contour

[0088] locking bar

[0089] Locking spring 33 control unit

[0090] 34 electrical cable

[0091] 35 additional electrical lines

[0092] 36 Hydraulic system

[0093] 37 hydraulic line

[0094] 38 Parking lock sensor

[0095] 39 Signal line

[0096] 40 Locking sensor

[0097] 41 additional signal lines

[0098] 42 sensor encoders

[0099] 43 sensor receivers

[0100] 100 Main axis

[0101] 101 Parking lock release direction

[0102] 102 Parking lock engagement direction

[0103] F1 actuation force

[0104] F2 spring force

[0105] F3 spring force

[0106] K_off designed piston position

[0107] No engaged piston position

[0108] P_from lay-out position

[0109] P_in insertion position

[0110] V_off designed locking position

[0111] V_in engaged locking position

[0112] Z_0 initial state

[0113] Z_off design state

[0114] Z_ein insertion state

[0115] Z_not emergency release state

Claims

Patent claims 1 . Parking lock system (1) for an automatic transmission of a motor vehicle, - with a parking lock wheel (7); - with a parking lock (2) which is engaged with the parking lock gear (7) in an engaged position (P_on) and disengaged in a disengaged position (P_off); - with an emergency release device (17) which is operatively connected and / or operatively connectable to the parking lock (2) in order to transfer the parking lock (2) from the engaged position (P_on) to the disengaged position (P_off) in an emergency situation; - with a parking lock actuator (15) which has a first piston (22) and a second piston (23), wherein the first piston (22) can be acted upon by an actuating force (F1) to transfer the parking lock (2) into the disengaged position (P_off), and the second piston (23) can be moved relative to the first piston (22) by the emergency release device (17) to transfer the parking lock (2) into the disengaged position (P_off), and wherein the parking lock actuator (15) has a locking device (27) for locking the first piston (22) in a piston position (K_on) assigned to the engaged position (P_on) and / or the piston position (K_off) assigned to the disengaged position (P_off); - with a parking lock sensor (38) which is designed to detect the engagement position (P_on) and the disengagement position (P_off) of the parking lock (2) and to provide it as sensor information; - with a control unit (33) which is designed to distinguish between an engaged state (Z_on) and a disengaged state (Z_off) of the parking lock (2) on the basis of the sensor information; characterized by a locking sensor (40) which is designed to detect a locking position (V_on) locking the engaged piston position (K_on) and a locking position (V_off) of the locking device (27) locking the disengaged piston position (K_off) and to provide them as further sensor information, wherein the control unit (33) is designed to additionally distinguish between an emergency release state (Z_not) initiated by the emergency release device (17) on the basis of the further sensor information.

2. Parking lock system (1) according to claim 1, characterized in that the locking sensor (40) is a position sensor which is designed to detect the engaged locking position (V_on) and the disengaged locking position (V_off) based on a change in position.

3. Parking lock system (1) according to claim 1 or 2, characterized in that the locking device (27) has a locking rod (31) which is displaceable in the axial direction with respect to a main axis (100) of the parking lock actuator (15) between the engaged locking position (V_on) and the disengaged locking position (V_off), wherein the locking rod (31) at least indirectly locks the first piston (22) in the engaged locking position (V_on) and the disengaged locking position (V_off).

4. Parking lock system (1) according to claim 3, characterized in that the locking sensor (40) is designed to detect an axial position of the locking rod (31).

5. Parking lock system (1) according to claim 3 or 4, characterized in that the locking sensor (40) has a sensor receiver (43) fixed to the parking lock actuator (15) and a sensor transmitter (42) which is motion-coupled to the locking rod (31) and which can be detected by the sensor receiver (43).

6. Parking lock system (1) according to one of the preceding claims, characterized in that the locking device (27) has an electromagnet (28), wherein the locking device (27) is arranged in one locking position (V_off) when the electromagnet (28) is energized and is arranged in the other locking position (V_on) when the electromagnet is de-energized.

7. Parking lock system (1) according to claim 3 and 6, characterized in that the locking device (27) has a locking spring (32) which Locking rod (31) holds and / or transfers in a non-energized state of the electromagnet (28) in one of the locking positions (V_on).

8. Parking lock system (1) according to claim 6 or 7, characterized in that the control unit (33) is designed to take into account the energized and / or the de-energized state of the electromagnet (28) when distinguishing between the engaged state (Z_on), the disengaged state (Z_off) and the emergency release state (Z_not).

9. Parking lock system (1) according to one of the preceding claims, characterized in that the control unit (33) is designed to take into account a reference variable for the actuating force (F1) when distinguishing between the engaged state (Z_on), the disengaged state (Z_off) and the emergency release state (Z_not).

10. A method for monitoring the parking lock system (1) according to one of the preceding claims, in which: - the engagement position (P_on) and the disengagement position (P_off) of the parking lock (2) are detected and provided as sensor information; - the engaged locking position (V_on) and the disengaged locking position (V_off) are recorded and provided as further sensor information; - based on the sensor information and the further sensor information, a distinction is made between the insertion state (Z_ein) and the release state (Z_aus) and the emergency release state (Z_not). 11 . Method according to claim 10, characterized in that -the insertion state (Z_on) is detected IF the insertion position (P_on) is detected AND the engaged locking position (V_on) is detected; - the disengagement state (Z_off) is detected IF the disengagement position (P_off) is detected AND the disengaged locking position (V_off) is detected; - the emergency release state (Z_not) is detected IF the release position (P_aus) is detected AND the locking position (V_ein) is detected.

12. Method according to claim 10 or 11, characterized in that in a first emergency unlocking scenario starting from the insertion state (Z_on) in which the control unit (33) is switched off, - the parking lock (2) is moved into the disengaged position (P_off) by the emergency release device (17); - the control unit (33) is switched on; - the release position (P_off) and the engaged locking position (V_on) are detected, whereby the emergency release state (Z_not) is detected based on the sensor information.

13. Method according to one of claims 10 to 12, characterized in that in a second emergency unlocking scenario starting from the insertion state (Z_ein) in which the control unit (33) is switched on, - the parking lock (2) is moved into the disengaged position (P_off) by the emergency release device (17); - a change from the insertion position (P_on) to the release position (P_off) and no change in the locking position (V_on) is detected, whereby the emergency release state (Z_not) is detected based on the sensor information.

14. Method according to one of claims 10 to 13, characterized in that the first piston (22) is transferred into the disengaged piston position (K_aus) when the actuating force (F1) is increased, and is automatically transferred into the engaged piston position (K_ein) when the actuating force (F1) is reduced, wherein - the disengagement state (Z_off) is reliably detected IF the actuating force (F1) is additionally increased; - the insertion state (Z_on) and the emergency release state (Z_off) are reliably detected IF the actuating force (F1) is also reduced.

15. Method according to one of claims 10 to 14, characterized in that the first piston (22) is locked without current in the engaged locking position (V_on) and is locked with current in the disengaged locking position (V_off), wherein - the disengagement state (Z_off) is reliably detected IF the locking device (27) is additionally energized; - the insertion state (Z_ein) and the emergency release state (Z_not) are reliably detected IF, in addition, the locking device (27) is de-energized.

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