Parking interlock in a vehicular transmission

Patent metadata

Field	Value
Publication number	US-11022218-B2
Application number	US-201916289720-A
Country	US
Kind code	B2
Filing date	Mar 1, 2019
Priority date	Mar 2, 2018
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A parking lock for a transmission of a motor vehicle having an interlocking element of a connecting rod that is biased against a parking lock disengagement direction to bring and keep a ratchet tooth of a locking pawl in engagement with a tooth space of a parking interlock gear during an engagement of the parking lock. The connecting rod is provided a spring force acting in a parking lock engagement direction from an inserting spring and a compressive force acting in the parking lock disengagement direction from a hydraulically actuatable actuator having first piston pressurizable to disengage the parking lock. A detent device actuatable by an electromagnet mechanically fixes the first piston in either a latched or unlatched piston position associated with an engaged or disengaged position of the parking lock, respectively. A system determines a current engagement position of the detent device by assessing an inductance at the electromagnet.

First claim

The invention claimed is:

1. A parking lock for a transmission of a motor vehicle, comprising:
a parking interlock gear ( 1 ) fixed to a transmission shaft of the transmission, the parking interlock gear ( 1 ) comprising a locking toothing including tooth spaces ( 1 a );
a locking pawl ( 2 ) pivotably mounted on a latch bolt ( 3 ), the locking pawl ( 2 ) comprising a ratchet tooth ( 2 a ) which engages into one of the tooth spaces ( 1 a ) of the locking toothing of the parking interlock gear ( 1 ) in an engaged position (P_ein) of the parking lock to block the parking interlock gear ( 1 ) and the transmission shaft against rotation;
a connecting rod ( 5 ) movable to change a current engagement position (P_ein, P_aus) of the parking lock, the connecting rod ( 5 ) comprising an interlocking element ( 6 ) axially displaceable on the connecting rod ( 5 ), the interlocking element ( 6 ) being spring-mounted against a parking lock disengagement direction relative to the connecting rod ( 5 ), the interlocking element ( 6 ) bringing the ratchet tooth ( 2 a ) of the locking pawl ( 2 ) into engagement with the one of the tooth spaces ( 1 a ) of the locking toothing of the parking interlock gear ( 1 ) during the engagement of the parking lock, the interlocking element ( 6 ) preventing the ratchet tooth ( 2 a ) of the locking pawl ( 2 ) from disengaging the one of the tooth spaces ( 1 a ) of the locking toothing of the parking interlock gear ( 1 ) in the engaged position (P_ein) of the parking lock;
an inserting spring ( 9 ) providing a spring force acting in a parking lock engagement direction on an end of the connecting rod ( 5 ) spaced from the interlocking element ( 6 );
a hydraulically actuatable actuator ( 10 ) providing a compressive force acting in the parking lock disengagement direction on the end of the connecting rod ( 5 ) spaced from the interlocking element ( 6 ), the hydraulically actuatable actuator ( 10 ) comprising a first piston ( 11 ) axially displaceably arranged in an actuator housing ( 14 ) and pressurized to disengage the parking lock;
a position sensor for determining the current engagement position (P_ein, P_aus) of the parking lock;
a detent device ( 13 ) actuatable by an electromagnet ( 13 a ), the first piston ( 11 ) of the hydraulically actuatable actuator ( 10 ) being mechanically fixable by the detent device ( 13 ) in either a latched piston position associated with the engaged position (P_ein) of the parking lock or in an unlatched piston position associated with a disengaged position (P_aus) of the parking lock; and
a system (Z) implemented in an electronic control unit (EGS) of the transmission, the system (Z) configured for determining a current engagement position of the detent device ( 13 ) by assessing a present inductance at the electromagnet ( 13 a ).

2. The parking lock of claim 1 ,
wherein the system (Z) comprises a two-position controller (Z 2 ) for controlling the electromagnet ( 13 a ) with a control signal (H 1 ), and
wherein the system (Z) comprises a determination means (Z 1 c ) for determining a time profile of the control signal (H 1 ) and for determining the current engagement position of the detent device ( 13 ) based on the time profile.

3. The parking lock of claim 2 ,
wherein the determination means (Z 1 c ) determines a frequency or period of the control signal (H 1 ) and an electric current (i_ist) supplied to a coil ( 13 c ) of the electromagnet ( 13 a ),
wherein the determination means (Z 1 c ) determines a current position of an armature ( 13 b ) of the electromagnet ( 13 a ) based on the frequency or period and the electric current (i_ist), and
wherein the determination means (Z 1 c ) infers the current engagement position of the detent device ( 13 ) based on the current position of the armature ( 13 b ) of the electromagnet ( 13 a ).

4. The parking lock of claim 3 , wherein the determination means (Z 1 c ) utilizes an electrical supply voltage of the coil ( 13 c ) of the electromagnet ( 13 a ) to determine the current position of the armature ( 13 b ) of the electromagnet ( 13 a ).

5. The parking lock of claim 3 , wherein the determination means (Z 1 c ) comprises a look-up table or a characteristic map or another mathematical function for determining with the control signal (H 1 ) the current position of the armature ( 13 b ) of the electromagnet ( 13 a ).

6. The parking lock of claim 1 , wherein the detent device ( 13 ) mechanically fixes the first piston ( 11 ) of the actuator ( 10 ) in the latched or unlatched piston position when the electromagnet ( 13 a ) acting on the detent device ( 13 ) is not electrically energized, such that the first piston ( 11 ) only changes between the latched and unlatched piston positions when the electromagnet ( 13 a ) is electrically energized.

7. The parking lock of claim 1 , wherein the detent device ( 13 ) mechanically fixes the first piston ( 11 ) of the actuator ( 10 ) in the latched or unlatched piston position when the electromagnet ( 13 a ) acting on the detent device ( 13 ) is electrically energized, such that the first piston ( 11 ) only changes between the latched and unlatched piston positions when the electromagnet ( 13 a ) is not electrically energized.

8. The parking lock of claim 1 , wherein a piston rod ( 11 a ) of the first piston ( 11 ) of the actuator ( 10 ) is articulatedly connected to the end of the connecting rod ( 5 ) spaced from the interlocking element ( 6 ).

9. The parking lock of claim 8 , further comprising an emergency release device which is mechanically brought into an operative connection with the piston rod ( 11 a ) of the first piston ( 11 ) of the actuator ( 10 ) to manually disengage the parking lock.

10. The parking lock of claim 1 , further comprising a selector lever ( 4 ) for transmitting the compressive force of the actuator ( 10 ) to the end of the connecting rod ( 5 ) spaced from the interlocking element ( 6 ), the selector lever ( 4 ) being rotatable about a selector-lever axis of rotation ( 3 a ) to specify the current engagement position (P_ein, P_aus) of the parking lock,
wherein the end of the connecting rod ( 5 ) spaced from the interlocking element ( 6 ) is articulatedly connected to the selector lever ( 4 ), and
wherein the position sensor is an inductive or capacitive sensor, a signal transmitter element (PSG) of the position sensor being arranged on the selector lever ( 4 ).

11. The parking lock of claim 10 , wherein the signal transmitter element (PSG) of the position sensor is attached to the selector lever ( 4 ) or is an integral element of the selector lever.

12. The parking lock of claim 10 , further comprising:
an emergency release device ( 15 ) which is mechanically brought into an operative connection with the selector lever ( 4 ) to manually disengage the parking lock,
a second piston ( 12 ) of the actuator ( 10 ), the first and second pistons ( 11 , 12 ) of the actuator ( 10 ) being axially displaceably arranged on a common longitudinal axis ( 12 c ) in the actuator housing ( 14 ),
wherein the second piston ( 12 ) is axially displaced against the spring force of the inserting spring ( 9 ) when the first piston ( 11 ) is hydraulically pressurized,
wherein the second piston ( 12 ) is mechanically connected to the selector lever ( 4 ) such that axial movement of the second piston ( 12 ) causes rotation of the selector lever ( 4 ) about the selector-lever axis of rotation ( 3 a ), and vice versa,
wherein the detent device ( 13 ) is also arranged in the actuator housing ( 14 ),
wherein the detent device ( 13 ) mechanically fixes the first piston

Assignees

• Zahnradfabrik Friedrichshafen

Inventors

• Schwegler Thomas
• Weinl Florian
• Jud Michael
• Haugg Armin
• Klein Julia

Classifications

• F16H63/3491

  Emergency release or engagement of parking locks or brakes · CPC title

• F16H63/3483

  with hydraulic actuating means · CPC title

• F16H63/3458 Primary

  with electric actuating means, e.g. shift by wire · CPC title

• F16H63/3433 Primary

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

• B60T8/17

  Using electrical or electronic regulation means to control braking {(detecting or indicating faulty operation B60T8/885)} · CPC title