Device for Locking a Piston Rod of a Piston of an Actuator Which is Pressurizable in Order to Disengage a Parking Lock and is Spring-Loaded in Order to Engage the Parking Lock

Abstract

In a device for locking a piston rod of a piston of an actuator, an armature rod of an electromagnet is axially movable counter to a preloading spring and includes two actuating contours. Latching mechanisms are operable to mechanically fix the piston. An axial distance between base points of the actuating contours is such that the piston is mechanically fixable by only one of the latching mechanisms in each case. Interlocking elements of both latching mechanisms are accommodated in an axially fixed manner in a sleeve, are radially displaceable, and are selectively engageable with the piston.

Claims

11. A device (2; 202) for locking a piston rod (7) of a piston (4) of an actuator, which is pressurizable in order to disengage a parking lock (3) and is spring-loaded in order to engage the parking lock (3), the device (2; 202) comprising: an electrically actuatable electromagnet (19) with an armature rod (20) that is axially movable against a spring force of a preloading spring (21), the armature rod (20) comprising two actuating contours (22, 23) that are axially spaced apart and face each other; wherein the actuating contour (22) positioned proximate the electromagnet (19) is associated with a first latching mechanism (24) operable to mechanically fix the piston (4) an engaged condition of the parking lock (3), wherein the actuating contour (23) positioned remote from the electromagnet (19) is associated with a second latching mechanism (25) operable to mechanically fix the piston (4) in a disengaged condition of the parking lock (3), wherein an axial distance (X) between a base point (26) of the actuating contour (22) positioned proximate the electromagnet (19) and a base point (27) of the actuating contour (23) positioned remote from the electromagnet (19) is sized such that the piston (4) is mechanically fixable by only one of the first and second latching mechanisms (24 or 25) in each of the engaged and disengaged conditions of the parking lock (3), wherein both of the first and second latching mechanisms (24, 25) are centrally arranged within the piston (4), interlocking elements (28, 29) of both of the first and second latching mechanisms (22, 23) are disposed within a housing-affixed component (30) in an axially fixed manner, and the interlocking elements (28, 29) are radially displaceable relative to the component (30) and are selectively engageable with the piston (4) by a respective actuating contour (22, 23), wherein the actuating contour (23) positioned remote from the electromagnet (19) blocks movement of the interlocking elements (29) of the second latching mechanism (25) counter to the spring force of the preloading spring (21) when the parking lock (3) is in the disengaged condition of the parking lock (3) and the electromagnet (19) is in an energized condition of the electromagnet (19), and the actuating contour (23) positioned remote from the electromagnet (19) releases the interlocking elements (29) of the second latching mechanism (25) for movement with the preloading spring (21) when the electromagnet (19) is in a non-energized condition of the electromagnet (19), and wherein the actuating contour (22) positioned proximate the electromagnet (19) blocks movement of the interlocking elements (28) of the first latching mechanism (24) with the preloading spring (21) when the parking lock (3) is in the engaged condition of the parking lock (3) and the electromagnet (19) is in the non-energized condition of the electromagnet (19), and the actuating contour (22) positioned proximate the electromagnet (19) releases the interlocking elements (28) of the first latching mechanism (24) for movement against the spring force of the preloading spring (21) when the electromagnet (19) is in the energized condition of the electromagnet (19).

12. The device of claim 11, wherein: the two actuating contours (22, 23) have an at least partially truncated cone shape; a base point (26, 27) of each of the two actuating contours (22, 23) has a smallest outer diameter of the two actuating contours (22, 23); and outer diameters of each of the two actuating contours (22, 23) constantly increase, at least partially, starting from the base point (26, 27) along an axial direction.

13. The device of claim 11, wherein: the piston (4) comprises a groove (31) at an inner side facing the armature rod (20); and the interlocking elements (28, 29) of the first and second latching mechanisms (24, 25) are insertable into the groove (31) in a latching manner with respect to the armature rod (20) and in a radial outward direction with respect to the two actuating contours (22, 23) and the piston rod (7) when the parking lock (3) is in either the engaged condition or the disengaged condition of the parking lock (3).

14. The device of claim 13, wherein the armature rod (20) has a first axial end position in a latched condition of one of the first and second latching mechanisms (24, 25), and the piston rod (7) is held in the engaged condition of the parking lock (3) with the one of the first and second latching mechanisms (24, 25) when the armature rod (20) is at the first axial end position.

15. The device of claim 14, wherein the armature rod (20) has a second axial end position in a latched condition of the other of the first and second latching mechanisms (24, 25), and the piston rod (7) is held in the disengaged condition of the parking lock (3) with the other of the first and second latching mechanisms (24, 25) when the armature rod (20) is at the second axial end position.

16. The device of claim 15, wherein the armature rod (20) has an axial intermediate position between the first and second axial end positions when both the first and second latching mechanisms (24, 25) are in a released condition.

17. The device of claim 11, wherein the first and second latching mechanisms (24, 25) are configured as ball stops and comprise balls as the interlocking elements (28, 29).

18. The device of claim 17, wherein: the ball stops (24, 25) are centrally arranged within the piston (4); the balls (28, 29) of the ball stops (24, 25) are accommodated in an axially fixed manner in the housing-affixed component (30); the housing-affixed component (30) is configured as a sleeve; and the balls (28, 29) of the ball stops (24, 25) are radially displaceable with respect to the sleeve (30) and are selectively engageable with the piston (4) by way of rolling at the respective actuating contour (22, 23).

19. The device of claim 11, wherein: the interlocking elements are configured as spring arms; first ends of the spring arms are fixed on the housing side; and second ends of the spring arms are each swivelable relative to a respective first end by way of the actuating contours and, as a result, are selectively engageable with the piston in a form-locking manner.

20. The device of claim 11, further comprising: a two-position controller configured for operating the electromagnet (19); and a determination means for determining a time profile of a control signal output by the two-position controller at the electromagnet (19), for determining a particular currently present axial position of the armature rod (20) based on the time profile, and for determining an operating condition of the first and second latching mechanisms (24, 25) in each case based on the particular currently present axial position of the armature rod (20).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Multiple exemplary embodiments of the invention are explained in greater detail with reference to the drawings, without being limited thereto.

[0051] Wherein:

[0052] FIG. 1 shows a highly schematicized partial representation of a parking lock system of an automatic transmission; and

[0053] FIG. 2a to FIG. 2e show an enlarged view of a device for actuating a parking lock of the parking lock system according to FIG. 1 in various operating conditions.

DETAILED DESCRIPTION

[0054] Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

[0055] A schematic part longitudinal cutaway view of a parking lock system 1 known from practical experience, including a device 2 for actuating a parking lock 3, is represented in FIG. 1. The device 2 includes an actuator, which includes a piston 4, which can be acted upon by fluid. The piston 4 is actuatable in the opening direction or in the direction of a disengaged condition of the parking lock 3, depending on the particular applied fluid pressure, counter to a spring unit 5 acting in the closing direction or an engaged condition of the parking lock 3. For this purpose, the piston 4 is arranged, displaceably in the axial direction, in a cylinder 6 of the actuator. Additionally, the piston 4 is connected to a deflecting mechanism 8 via a piston rod 7. In the present case, the deflecting mechanism 8 includes a rotary disk 9, which is designed to be rotatable in the area of a pin 10. The spring unit 5 is designed as a compression spring in the present case and is connected at one end to the rotary disk 9. At the other end, the spring unit is supported in the area of a housing 11.

[0056] Moreover, the rotary disk 9 is operatively connected to a parking interlock rod 14, which is coupled to a parking interlock cone 15. The parking interlock cone 15 cooperates with a parking pawl 16. The parking pawl 16 is engageable, via an axial movement of the piston 4, with a parking interlock gear 17, which is rotationally fixed to an output shaft of a vehicle drive train, in order to rotationally fix the output shaft. If the parking pawl 16 is guided out of the engagement with the parking interlock gear 17 via an axial movement of the piston 4 in the opposite direction, the parking lock 3 is disengaged and the output shaft can rotate.

[0057] The device 202 represented in FIG. 2a through FIG. 2e for actuating the parking lock 3 has the same functionality as the device 2. Therefore, the same reference numbers are used in the description and in the drawing for structurally and functionally identical components of the devices 2 and 202.

[0058] With respect to the device 202, the spring unit 5 is arranged between an end face 12 of the piston 4 and an inner side 13 of the cylinder 6 facing the end face 12 of the piston 4. The spring unit 5 is designed as a compression spring in each case, in order to be able to engage the parking lock 3 in the non-pressurized condition of the piston 4.

[0059] FIG. 2a through FIG. 2e each show a detailed single view of the device 202 for actuating the parking lock 3 in various operating conditions, which partly correspond to an engaged condition of the parking lock 3 or to a disengaged condition of the parking lock 3. With respect to the device 202, the spring unit 5 is arranged within the cylinder 6 between the end face 12 of the piston 4 and the inner side 13 of the cylinder 6 and is designed as a compression spring. In the position of the piston 4 shown in FIG. 2a, the parking lock 3 of the parking lock system 1 is engaged.

[0060] In order to disengage the parking lock 3, the piston 4 is hydraulically pressurized via a hydraulic port 18 in the area of a further end face 12A and is transferred, against the spring force of the spring unit 5, out of the first position represented in FIG. 2a into the second position represented in FIG. 2d and FIG. 2e.

[0061] In order to avoid an undesirable engagement of the parking lock 3 as well as an undesirable disengagement of the parking lock 3, the device 202 is designed in the manner described in greater detail in the following.

[0062] The device 202 includes an interlocking unit including an electromagnet 19. An armature rod 20 of the electromagnet 19 is axially displaceable within the piston 4 against the spring force of a preloading spring 21 and includes two actuating contours 22, 23 of a locking unit, which are axially spaced apart from each other and face each other. The actuating contour 22 close to the magnet is associated with a first latching mechanism 24 of the locking unit, with the aid of which the piston 4 is mechanically fixable in the engaged condition of the parking lock 3. The first latching mechanism 24 is designed as a ball stop in the present case. The actuating contour 23 remote from the magnet is associated with a second latching mechanism 25 of the locking unit, with the aid of which the piston 4 is mechanically fixable in the disengaged condition of the parking lock 3. The second latching mechanism 25 is also designed as a ball stop in the present case.

[0063] An axial distance X between a base point 26 of the actuating contour 22 close to the magnet and a base point 27 of the actuating contour 23 remote from the magnet is sized such that the piston 4 is mechanically fixable by only one of the ball stops 24 or 25 in each case.

[0064] The actuating contours 22 and 23 are designed at least approximately in the shape of a truncated cone, at least partially or in sections. The base points 26 and 27 of the actuating contours 22 and 23 each have the smallest outer diameter of the actuating contours 22, 23. Additionally, the outer diameters of the actuating contours 22, 23 constantly increase, at least partially or in areas, starting from the base points 26 and 27, respectively, as the axial distance from the base points 26 and 27 increases, in order to be able to radially displace the balls 28 and 29, respectively, to the extent described in greater detail above.

[0065] Both ball stops 24 and 25 are centrally arranged within the piston 4. The balls 28, 29 of the two ball stops 24, 25 are accommodated in an axially fixed manner in a housing-affixed sleeve 30, wherein axial movements of the balls 28, 29 with respect to the sleeve are essentially not possible. Moreover, the balls 28, 29 are radially inwardly as well as radially outwardly displaceable with respect to the sleeve 30 and can be brought into engagement or out of the engagement with the piston 4 by way of rolling at the associated actuating contour 22 or 23, respectively. The piston 4 is designed including a radial inner groove 31, into which the balls 28 and 29 of the actuating contour 22 and 23, respectively, can be brought into engagement through the sleeve 30 in the engaged condition or in the disengaged condition of the parking lock 3.

[0066] In the latter operating condition of the ball stops 24 and 25, the piston 4 is not displaceable in the axial direction of the device 202 with respect to the cylinder 6 and has a locked operating condition.

[0067] The armature rod 20 is guidable out of the position shown in FIG. 2a into the position shown in FIG. 2e against the spring force of the preloading spring 21 by energizing the electromagnet 19, in order to lock the piston 4 in the disengaged condition of the parking lock 3 and to reliably avoid an undesirable engagement of the parking lock 3. The locking unit is then interlocked by the interlocking unit.

[0068] In the non-energized condition of the electromagnet 19, the preloading spring 21 holds the armature rod 20 in the position shown in FIG. 2a when the parking lock 3 is engaged. Thereupon, the actuating contour 22 holds the balls 28 of the ball stop 24 in the radial inner groove 31, which is designed including lateral faces 32 and 33, each of which is pitched with respect to the radial direction. Thereupon, the locking unit is interlocked by the interlocking unit. Via the beveled lateral surfaces 32 and 33 of the radial inner groove 31, an undesirable misalignment or jamming of the ball stops 24 and 25 is prevented in a simple way.

[0069] If a driver-side demand to disengage the parking lock 3 is issued, for example, the electromagnet 19 is appropriately energized and pulls the armature rod 20 against the spring force of the preloading spring 21 out of the position shown in FIG. 2a in the direction of the axial position shown in FIG. 2b. Due to this axial displacement of the armature rod 20, the balls 28 of the ball stop 24 roll at the outer side of the actuating contour 22 and are guided radially inward, with respect to the piston 4, out of the engagement of the radial inner groove 31 of the piston 4. This is the case, in particular, when a hydraulic pressure is applied at the piston 4 via the hydraulic port 18, which displaces the piston 4 against the spring unit 5 in the axial direction, which corresponds to the disengaged operating condition of the parking lock.

[0070] The axial displacement of the armature rod 20 caused by the energization of the electromagnet 19 is initially limited, since the actuating contour 23 remote from the magnet comes to rest against the radially internal balls 29 in the manner represented in FIG. 2b and further actuating travel of the armature rod 20 in the direction of the end of the armature rod 20 facing the electromagnet 19 is prevented.

[0071] The released piston 4 is displaced away from the electromagnet 19 counter to the spring element 5 by the applied hydraulic pressure. During this actuating movement of the piston 4, the spring unit 5 is increasingly preloaded. FIG. 2c shows the device 202 in the latter operating condition, in which the piston 4 is locked neither by the ball stop 24 nor by the ball stop 25. As the displacement travel of the piston 4 continues to increase, the extent of overlap between the radial inner groove 31 and the ball stop 25 increases until the balls 29 is guidable radially outward by the actuating contour 23 remote from the magnet, through the sleeve 30, into the radially inner groove 31. In the process, the balls 29 are pressed radially outward into the radial inner groove 31 by the further axial actuating movement of the armature rod 20 in the direction of the electromagnet 19, which is now possible. In this operating condition of the device 202, an axial actuating movement of the piston 4 is blocked by the ball stop 25 due to the energized condition of the electromagnet 19. Therefore, in the case of a pressure drop in the area of the hydraulic port 18, an undesired engagement of the parking lock 3 is reliably avoided by way of the preloaded spring unit 5.

[0072] If there is a demand to engage the parking lock 3, the energization of the electromagnet 19 is switched off. Thereupon, the armature rod 20 is initially guided by the preloading spring 21 into the position shown in FIG. 2d, in which further actuating travel of the armature rod 20 is limited by way of the actuating contour 22 close to the magnet resting against the balls 28 of the ball stop 24. In this position of the armature rod 20, the balls 29 of the ball stop 25 is guidable radially inward, with respect to the piston 4, out of the engagement of the radial inner groove 31 and the piston 4 is releasable. If the spring force of the spring unit 5 exceeds the pressure applied at the piston 4 via the hydraulic port 18 or the resultant actuating force in the direction of the disengaged operating condition of the parking lock 3, the piston 4 is transferred in the direction of its axial position shown in FIG. 2a, which corresponds to the engaged operating condition of the parking lock 3.

[0073] In the axial position of the piston 4 shown in FIG. 2b, a radial actuating movement of the balls 28 is released by the piston 4, since the radial inner groove 31 is then in overlap with the balls 28 and the armature rod 20 is displacable by the preloading spring 21 in the direction of the spring unit 5. Therefore, the piston 4 is locked in the non-energized condition of the electromagnet 19 and in the engaged condition of the parking lock 3, and an undesirable disengagement of the parking lock 3 is prevented.

[0074] In the position shown in FIG. 2a, the armature rod 20 assumes a different axial position than the position of the piston 4 shown in FIG. 2e. Therefore, the locking state of the piston 4 or the armature rod 20 is determinable with the aid of a sensor associated with the electromagnet 19, which can be designed, for example, as a Hall sensor. This possibility offers a simple implementation of various functions, such as an adaptation of the sensor in the disengaged operating condition of the parking lock 3. A sensor 34, which is, for example, a Hall sensor, is also associated with the parking lock 3. The engaged operating condition as well as the disengaged operating condition of the parking lock 3 is determinable in a simple way with the aid of the sensor 34.

[0075] Additionally or alternatively, it is also possible that a sensor is associated with the electromagnet 19, whose mode of operation is known from DE 10 2016 221 477 A1. This sensor includes a two-position controller for operating an actuator, and a determination means. The determination means is designed for determining a time profile of the control signal output by the two-position controller and, on the basis thereof, determining the operating condition. In this case, the actuator corresponds to the electromagnet 19 and the control signal corresponds to the actuating current of the electromagnet 19. This means, the current axial position of the armature rod 20 is determinable with the aid of a sensor of this type depending on the particular output actuating current as well as the coil current setting in, in the area of a coil of the electromagnet 19. A mutual plausibility check of the sensor signals is possible with the aid of a comparison of the sensor signals of the sensor and of the sensor 34.

[0076] With the aid of the above-described device 202, the accuracy of the sensor provided for determining the axial position of the armature rod 20 and/or of the piston 4 and, therefore, also the operating condition of the device 2, can be improved in a simple way via an appropriate adaptation in the vehicle operation. An adaptation of this type can be carried out, in principle, in both locking positions of the piston 4.

[0077] Moreover, it is also possible to design the latching mechanisms of the locking unit not to include the interlocking elements designed as balls, but rather including interlocking elements designed as spring arms. The spring arms are swivelably operatively connected to the cylinder 6 and preferably include a hook-like end. Interlocking elements of this type are known, for example, from EP 1 960 701 B1 and are swivelable radially outward with the aid of the actuating contours 22 and 23, in order to prevent an actuating movement of the piston 4 or, in the swiveled-in condition, to release the piston 4.

[0078] Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.

REFERENCE CHARACTERS

[0079] 1 parking lock system [0080] 2 device [0081] 3 parking lock [0082] 4 piston [0083] 5 spring unit [0084] 6 cylinder [0085] 7 piston rod [0086] 8 deflecting mechanism [0087] 9 rotary disk [0088] 10 pin [0089] 11 housing [0090] 12 end face of the piston [0091] 12A further end face of the piston [0092] 13 inner side of the cylinder [0093] 14 parking interlock rod [0094] 15 parking interlock cone [0095] 16 parking pawl [0096] 17 parking interlock gear [0097] 18 hydraulic port [0098] 19 electromagnet [0099] 20 armature rod [0100] 21 preloading spring [0101] 22 actuating contour [0102] 23 actuating contour [0103] 24 latching mechanism, ball stop [0104] 25 latching mechanism, ball stop [0105] 26 base point of the actuating contour 22 [0106] 27 base point of the actuating contour 23 [0107] 28 interlocking element, ball of the ball stop 24 [0108] 29 interlocking element, ball of the ball stop 25 [0109] 30 sleeve [0110] 31 radial inner groove [0111] 32, 33 lateral surface of the radial inner groove 31 [0112] 32A to 33B lateral surfaces of the radial inner grooves 45 and 46 [0113] 34 sensor [0114] X axial distance of the base points