Device for actuating a parking lock means of an automatic transmission and method for operating such a device

Patent metadata

Field	Value
Publication number	US-11746902-B2
Application number	US-202017604232-A
Country	US
Kind code	B2
Filing date	Mar 20, 2020
Priority date	Apr 17, 2019
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

Abstract

A device ( 1 ) for actuating a parking lock device ( 2 ) of an automatic transmission includes a piston ( 3 ) guided in a cylinder ( 5 ) and hydraulically displaceable counter to a spring force of an actuation spring ( 4 ). The piston ( 3 ) is form-lockingly fixable in a first position and in a second position by radially displaceable blocking elements ( 26 ) of a blocking device ( 15 ). The blocking elements ( 26 ) are radially displaceable by an actuation element ( 17 ). The radial displacement path of the blocking elements ( 26 ) and an operating condition of the actuation element ( 17 ) corresponding thereto in the first position of the piston ( 3 ) deviate from the radial displacement path of the blocking elements ( 26 ) and the operating condition of the actuation element ( 17 ) corresponding thereto in the second position of the piston ( 3 ).

First claim

The invention claimed is:

1. A device ( 1 ) for actuating a parking lock device ( 2 ) of an automatic transmission, comprising:
a piston ( 3 ) guided in a cylinder ( 5 ) and hydraulically displaceable counter to a spring force of an actuation spring ( 4 );
a blocking device ( 15 ) comprising radially displaceable blocking elements ( 26 ), the piston ( 3 ) bringable into an operative connection with a parking pawl ( 13 ), the piston ( 3 ) form-lockingly fixable by the radially displaceable blocking elements ( 26 ) of the blocking device ( 15 ) both in a first position corresponding to an engaged operating condition of the parking lock device ( 2 ) and in a second position corresponding to a disengaged operating condition of the parking lock device ( 2 ); and
an actuation element ( 17 ), the blocking elements ( 26 ) radially displaceable by the actuation element ( 17 ),
wherein a radial displacement path of the blocking elements ( 26 ) in the first position of the piston ( 3 ) and a corresponding operating condition of the actuation element ( 17 ) deviate from the radial displacement path of the blocking elements ( 26 ) in the second position of the piston ( 3 ) and the corresponding operating condition of the actuation element ( 17 ),
wherein the blocking elements ( 26 ) are configured as balls that are axially and radially guided in recesses ( 34 ) of a guide sleeve ( 35 ) operatively connected to the cylinder ( 5 ).

2. The device of claim 1 , wherein:
the actuation element ( 17 ) is configured as at least approximately rotationally symmetrical and comprises, consecutively in an axial extension direction (X) of the actuation element ( 17 ), a plurality of sections ( 24 , 25 , 27 ) with one cylindrical section ( 24 ) and two sections ( 25 , 27 ) widening in the shape of a truncated cone starting from the cylindrical section ( 24 );
the blocking elements ( 26 ) rest against the sections ( 24 , 25 , 27 ) of the actuation element ( 17 ) respectively and are displaceable in a radial direction relative to the actuation element ( 17 ) by moving the actuation element in the axial extension direction (X); and
an opening angle of a first truncated cone-shaped section ( 25 ) of the two sections ( 25 , 27 ) adjacent to the cylindrical section ( 24 ) in the axial extension direction (X) of the actuation element ( 17 ) is larger than the opening angle of a second truncated cone-shaped section ( 27 ) of the two sections ( 25 , 27 ) adjacent to the truncated cone-shaped section ( 25 ).

3. The device of claim 2 , wherein:
the piston ( 3 ) comprises a plurality of hollow-cylindrical sections ( 29 through 31 ) proximate a radial inner side ( 28 ) of the piston ( 3 ) facing the actuation element ( 17 ), the hollow-cylindrical sections ( 29 through 31 ) extending in an axial direction and situated adjacent to one another;
an inner diameters of the hollow-cylindrical sections ( 29 through 31 ) deviate from one another, the inner diameter of a middle hollow-cylindrical section ( 30 ) of the hollow-cylindrical sections ( 29 through 31 ) is smaller than the inner diameters of the outer hollow-cylindrical sections ( 29 , 31 ) of the hollow-cylindrical sections ( 29 through 31 ) adjacent to the middle hollow-cylindrical section ( 30 ) on either side; and
the blocking elements ( 26 ) form-lockingly project into a first one of the outer hollow-cylindrical sections ( 29 , 31 ) in the first position of the piston ( 3 ) and form-lockingly project into a second one of the outer hollow-cylindrical sections ( 29 , 31 ) in the second position of the piston ( 3 ).

4. The device of claim 3 , wherein the blocking elements ( 26 ) rest, in the axial direction, against a respective truncated cone-shaped section ( 32 , 33 ) of the piston ( 3 ), which are provided between the middle hollow-cylindrical section ( 30 ) and one of the outer hollow-cylindrical sections ( 29 or 31 ) on either side, when the blocking elements ( 26 ) project into the hollow-cylindrical sections ( 29 or 31 ) of the piston ( 3 ).

5. A method for operating the device ( 1 ) of claim 4 , wherein a spring device ( 18 ) is provided between the cylinder ( 5 ) and the actuation element ( 17 ), a spring force of the spring device ( 18 ) acting at the actuation element ( 17 ) in a direction of a position of the actuation element ( 17 ), in which the blocking elements ( 26 ) rest against the second truncated cone-shaped section ( 27 ) of the actuation element ( 17 ), and wherein the actuation element ( 17 ) is actuatable counter to the spring device ( 18 ) by an electromagnetic actuation device ( 16 ), the method comprising:
in response to a demand for releasing the blocking device ( 15 ), supplying current to the electromagnetic actuation device ( 16 ) and displacing the actuation element ( 17 ) in the axial direction counter to the spring force of the spring device ( 18 ) in order to displace the blocking elements ( 26 ) radially inward along the truncated cone-shaped sections ( 32 , 33 ) of the piston ( 3 ) and release the positive engagement between the blocking elements ( 26 ) and the piston ( 3 ); and
displacing the piston ( 3 ) in the axial direction (X) between the first position and the second position in order to engage or disengage the parking lock device ( 2 ).

6. The method of claim 5 , wherein a sensor ( 40 ) is provided for determining an axial actuation travel of the actuation element ( 17 ), the method further comprising:
determining the axial position of the actuation element ( 17 ) with the sensor ( 40 ); and
determining the operating condition of the blocking device ( 15 ) as a function of the determined axial position of the actuation element ( 17 ).

7. The method of claim 6 , further comprising determining an engaged operating condition or a disengaged operating condition of the parking lock device ( 2 ) with a further sensor ( 38 ).

8. The method of claim 7 , further comprising, in the presence of a deviation greater than a threshold value by the sensor ( 40 ) between a demanded position of the actuation element ( 17 ) and a current position of the actuation element ( 17 ), detecting a non-engaged operating condition or a non-disengaged operating condition of the parking lock device ( 2 ).

9. The method of claim 8 , classifying the determined operating condition from the further sensor ( 38 ) as faulty when a deviation greater than the threshold value is determined by the sensor ( 40 ) that is associated with the actuation element ( 17 ).

10. The method of claim 9 , further comprising, upon detection of a non-engaged operating condition or a non-disengaged operating condition of the parking lock device ( 2 ) or upon classification of an operating condition of the parking lock device ( 2 ) as faulty:
outputting one or more of a haptic signal, an optical signal, and an acoustic signal for an operator of a vehicle that includes an automatic transmission that includes the device ( 1 ) and the parking lock device ( 2 ); and/or
initiating one or both of a substitute measure for actuating the parking lock device ( 2 ) and a vehicle-specific escalation strategy.

11. The device of claim 3 , wherein, when the piston ( 3 ) is in a position between the first position and the second position, the blocking elements ( 26 ) are situated radially between the middle hollow-cylindrical section ( 30 ) of the piston ( 3 ) and the first truncated cone-shaped section ( 25 ) of the actuation element ( 17 ) adjacent to the cylindrical section ( 24 ).

12. The device of claim 1 , wherein:
the piston ( 3 ) comprises hollow-cylindrical sections ( 29 , 31 ) proximate a radial inner side ( 28 ) of the piston ( 3 ) facing the act

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Schwegler Thomas
• Jabs Sven
• Bisping Andreas
• Weinl Florian

Classifications

• F16H63/3483 Primary

  with hydraulic actuating means · CPC title

• B60T1/005

  by locking of wheel or transmission rotation · CPC title

• F16H61/12

  Detecting malfunction or potential malfunction, e.g. fail safe (in control of hydrostatic gearing F16H61/4192) {; Circumventing or fixing failures} · CPC title

• F16H63/3433

  Details of latch mechanisms, e.g. for keeping pawls out of engagement · CPC title

• F16H63/48

  Signals to a parking brake {or parking lock; Control of parking locks or brakes being part of the transmission} · CPC title