DE102021210669A1 - Parking lock with ratchet prevention - Google Patents

Abstract

In a parking lock 1, comprising at least one parking lock wheel (2) firmly connected to a drive train and a parking lock pawl (5) that can be brought into operative connection with the parking lock wheel (2) for locking and unlocking the parking lock (1), the parking lock wheel (2) having a plurality of teeth (4) and tooth gaps (3) and wherein the parking lock pawl (5) includes a ratchet tooth (23), and wherein the parking lock wheel (2) has a rotational movement about a rotation axis (R) and the parking lock pawl (5) has a pivoting movement about a pivot axis (S) can perform, ratcheting should be largely prevented and the associated wear and tear on the parking lock wheel or on the parking lock pawl should be reduced. This is achieved in that the parking lock (1) comprises at least one ratchet wheel (6; 7) which can be rotated about the axis of rotation (R) relative to the parking lock wheel (2), the parking lock (1) being able to be brought into an open position in which a Tooth gap (3) of the parking lock wheel (2) and a ratchet wheel tooth gap (17; 19) of the at least one ratchet wheel (6; 7) are flush, in order to lock the parking lock (1) and the drive train connected thereto, the parking lock (1) can be brought into a closed position in which a tooth gap (3) of the parking lock wheel (2) and a ratchet wheel tooth gap (17; 19) of the at least one ratchet wheel (6; 7) are rotated relative to one another, to prevent the parking lock (1) from locking , and wherein the parking lock (1) further comprises a centrifugal governor (22) coupled to the at least one ratchet wheel (6; 7), and wherein the centrifugal governor (22) is designed in such a way and is coupled to the at least one ratchet wheel (6; 7). that the parking lock (1) can be brought from the open position into the closed position depending on the speed.

Description

The invention relates to a parking lock, in particular for an automatic transmission of a motor vehicle, according to the preamble of the independent patent claim.

As is known, a parking lock of an automatic transmission is a device which can secure the motor vehicle in which the automatic transmission is installed against rolling away. In order to fulfill this task, the parking lock is connected to the transmission output shaft in a torque-proof manner, while the transmission output shaft in turn is operatively connected to the drive wheels. This allows the parking lock to act as a lock for the transmission output shaft.

In this context, it is in particular the task of such parking locks or parking lock systems to lock the drive train. This is typically done by bringing a ratchet tooth of a parking lock pawl, which acts as a locking element, into the recess, usually formed by a tooth gap, of a parking lock wheel that is firmly connected to the drive train.

Typically, the parking lock is engaged (i.e. the drive train is locked) mechanically by the spring force of an engagement spring, for example a torsion spring, which presses the parking lock pawl against the parking lock wheel with a defined force. To disengage the parking lock (i.e. unlocking the drive train), a hydraulic system acting against the force of the engagement spring is usually provided in the form of a hydraulically actuable parking lock piston arranged in a parking lock cylinder.

On the one hand, the parking lock must be prevented from locking at high vehicle speeds (proportional to the speed of the parking lock wheel or the drive train). On the other hand, when the vehicle is stationary or traveling at low speed, it must be ensured that the parking lock is locked or the drive train is locked.

In other words, the parking lock must not engage if the current speed n is greater than a defined, upper limit speed n2, i.e. n > n2. However, the parking lock must engage when the current speed n is less than a defined, lower limit speed n1. If the current speed n is between the defined lower and upper limit speed, i.e. n1 < n < n2, then the parking lock may engage.

Solutions for locking the drive train are known from the prior art, in that a ratchet tooth of a parking lock pawl is brought into the recess of a parking lock wheel that is firmly connected to the drive train.

In addition, according to other solutions known from the prior art, such as from document DE 10 2010 042 917 A1 the geometry of the edge of the parking lock pawl and the recess (i.e. in particular the angular dimensions of the edges) are designed in such a way that at a current speed n greater than the upper speed n2, ie n > n2, the parking lock pawl does not engage in the recess due to the dynamics, but is rejected by the flanks and pushed out of the recess.

This prevents the parking lock from locking. Specialists refer to this locking process as so-called “ratcheting”.

If the current speed n is less than the lower speed n1, i.e. n < n1, the parking lock pawl is not rejected and the parking lock locks.

The following is from the document DE 10 2017 212 093 A1 Another solution is known, whereby deflection contours on the teeth of the parking lock wheel ensure that the ratchet tooth is catapulted in a critical speed range of the parking lock wheel over a tooth gap adjacent to the respective tooth and that contact of the tooth flanks of the parking lock pawl with the tooth flanks of the parking lock wheel in the critical speed range is avoided.

Because with the ones from the documents DE 10 2010 042 917 A1 and DE 10 2017 212 093 A1 known solutions, the speed-dependent requirement of a rejection or acceptance of the engagement process is implemented by the geometry of the recesses or tooth gaps of the parking lock wheel and the geometries of the parking lock pawl, the freedom of design of these elements is adversely restricted.

These known solutions also have the disadvantage that the ratcheting process represents a heavy load and can lead to excessive wear on the parking lock wheel or on the parking lock pawl, in particular on the flanks of the parking lock wheel or the parking lock pawl.

For this reason, the parking lock wheel and parking lock pawl must be specially designed that they can withstand the heavy loads during the ratcheting process. Otherwise, such wear and tear can have the disadvantageous consequence that the requirements for engagement and reject speeds mentioned at the outset are no longer met.

In other words, only a defined number of ratchets is desired. According to other solutions known from the prior art, ratchet processes must therefore be recognized in a complex manner by means of a ratchet detection, with the system generating a warning message when a critical number of ratchet processes is exceeded.

It is therefore an object of the invention to provide a parking lock which overcomes the disadvantages of the known prior art and, in particular, largely prevents ratcheting and, as a result, reduces wear on the parking lock wheel or on the parking lock pawl.

This problem is solved by a parking lock with the features of independent patent claim 1 .

Further preferred configurations and advantages emerge from the dependent patent claims.

According to the invention, the parking lock comprises at least one ratchet wheel that can be rotated about the axis of rotation relative to the parking lock wheel, with the parking lock being able to be brought into an open position in which a tooth gap of the parking lock wheel and a ratchet wheel tooth gap of the at least one ratchet wheel are flush, in order to lock the parking lock and the associated device connected drive train, and wherein the parking lock can be brought into a closed position in which a tooth gap of the parking lock wheel and a ratchet tooth gap of the at least one ratchet wheel is twisted relative to one another to prevent locking of the parking lock.

The parking lock also includes a centrifugal governor coupled to the at least one ratchet wheel, and the centrifugal governor is designed and coupled to the at least one ratchet wheel in such a way that the parking lock is a function of the speed, i.e. dependent on the speed of the parking lock wheel or the drive train, from the open position to the closed position can be brought.

This advantageously means that rotating the at least one ratchet wheel relative to the parking pawl wheel prevents the parking pawl from falling into the tooth gap of the parking pawl wheel or prevents ratcheting.

Furthermore, the parking lock according to the invention advantageously does not make any special demands on the geometries of the parking lock wheel or the parking lock pawl.

For the purposes of the present invention, a centrifugal governor is understood as an element that uses the centrifugal force to regulate a speed, here the speed of the parking lock wheel or the drive train. Typically, such a centrifugal governor comprises mass elements that are set in rotation and an element that generates a counterforce, for example in the form of a spring element.

For the purposes of the present invention, the parking lock according to the invention is designed in such a way that the at least one ratchet wheel is in an open position at a current speed n lower than the lower speed n1, i.e. n <n1, and locks the parking lock, while the at least one ratchet wheel at a current speed n greater than the upper speed n2, i.e. n > n2, is in a closed position and the parking lock pawl cannot engage in the reduced or reduced recess due to the mutually offset tooth gaps or the parking lock does not lock.

The centrifugal governor preferably comprises a first and second mass element that can be moved by means of centrifugal force along a first and second guide pin, as well as an element that generates a counterforce, in particular a spring element, with the at least one ratchet wheel also being at an angle (α) to the guide pins comprises second guide grooves, wherein the first and second mass element each comprise a corresponding first and second guide element engaging in the guide grooves and the centrifugal governor is thus coupled to the at least one ratchet wheel in such a way that the parking lock can be brought from the open position into the closed position as a function of the speed is.

The parking lock according to the invention can include a single ratchet wheel. However, according to a preferred development of the present invention, the parking lock according to the invention comprises a plurality of ratchet wheels, with the parking lock particularly preferably comprising an even number of ratchet wheels.

The parking lock according to the invention particularly preferably comprises a first ratchet wheel and a second ratchet wheel, wherein the parking lock is designed such that the first ratchet wheel and the second ratchet wheel can be rotated in opposite directions for locking and unlocking.

This has the advantage that moments of inertia that act on the ratchet wheels when the drive system accelerates or decelerates are compensated for by the ratchet wheels that are adjusted in opposite directions. As a result, the adjustment mechanism is not influenced by the moments of inertia.

The first and second guide grooves of the at least one ratchet wheel are preferably at an angle (α) to the guide pins.

In this context, a further angle (β), which changes depending on the rotation of the at least one ratchet wheel, can be defined. Here, for example, in the open position, in which the tooth gap of the parking lock wheel and the ratchet wheel tooth gap of the ratchet wheel are flush with one another, an angle (β1) can be defined, while in a closing or closed position, in which the tooth gap of the parking lock wheel and the ratchet wheel tooth gap of the ratchet wheel are rotated relative to each other, an angle (β2) can be defined, the angle (β2) > angle (β1).

In other words, the difference between the angles (β2) and (β1) corresponds to the rotation of the ratchet wheel relative to the parking lock wheel, which must be large enough so that the ratchet tooth of the parking lock pawl can no longer fall into the recess.

Within the meaning of the present application, the following angular relationship applies: α1−β1=α2+β2.
In an open position of the parking lock, the current speed n is preferably less than the lower speed n1, ie n<n1, while in a closed position of the parking lock, the current speed n is greater than the upper speed n2, ie n>n2, where n1 is in a preferred speed range of the parking lock wheel from 150 rpm to 180 rpm, while n2 is in a preferred speed range of the parking lock wheel from 400 rpm to 450 rpm.

In other words, the preferred speed range is dependent on the requirement for the parking lock and the installation position of the parking lock. Typically, the parking lock should engage below a certain vehicle speed of, for example, around 1 to 1.5 km/h with regard to the lower speed n1, while the parking lock should no longer engage with regard to the upper speed n2 above a certain vehicle speed of, for example, around 3 km/h. The vehicle speed is proportional to the speed of the parking lock wheel as a function of the wheel circumference and transmission ratio, these vehicle speeds usually corresponding to the above-mentioned, preferred lower speed range n1 from 150 rpm to 180 rpm or the above-mentioned, preferred upper speed range n2 from 400 rpm to 450 rpm .

• 1 eine perspektivische Ansicht einer ersten bevorzugten Ausführungsform der erfindungsgemässen Parksperre mit einem einzigen Sperrrad in einer offenen Position;
• 2 eine Obenansicht der ersten bevorzugten Ausführungsform der erfindungsgemässen Parksperre mit einem einzigen Sperrrad in einer offenen Position;
• 3 eine Obenansicht der ersten bevorzugten Ausführungsform der erfindungsgemässen Parksperre mit einem einzigen Sperrrad in einer geschlossenen Position;
• 4 eine Seitenansicht einer zweiten bevorzugten Ausführungsform der erfindungsgemässen Parksperre mit zwei Sperrrädern in einer offenen Position;
• 5 eine Seitenansicht der zweiten bevorzugten Ausführungsform der erfindungsgemässen Parksperre mit zwei Sperrrädern in einer geschlossenen Position.

The invention is explained in more detail below with reference to the attached figures. Show it:

• 1 a perspective view of a first preferred embodiment of the inventive parking lock with a single ratchet wheel in an open position;
• 2 a top view of the first preferred embodiment of the inventive parking lock with a single ratchet wheel in an open position;
• 3 a top view of the first preferred embodiment of the inventive parking lock with a single ratchet wheel in a closed position;
• 4 a side view of a second preferred embodiment of the inventive parking lock with two ratchet wheels in an open position;
• 5 a side view of the second preferred embodiment of the inventive parking lock with two ratchet wheels in a closed position.

Below and with reference to the 1 until 5 a first preferred exemplary embodiment of the parking lock 1 for an automatic transmission of a motor vehicle is described in more detail.

1 shows a perspective view of a first preferred embodiment of the parking lock 1 with a single ratchet wheel 6 in an open position in which a tooth space 3 of the parking lock wheel 2 and a ratchet tooth space 17 of a ratchet wheel 6 are flush. In this open position, the parking lock 1 and the drive train connected to it can be locked by a ratchet tooth 23 of an in 2 shown parking pawl 5 in the flush to each other through the tooth gaps 3; 17 brought recess formed or the parking lock can be inserted. In this case, there is typically an operative connection between the parking lock gear 2 and the parking lock pawl 5 , for example by means of an insert spring that presses the parking lock pawl 5 against the parking lock gear 2 with a defined force. In the open position shown here the current speed n is lower than the lower speed n1, ie n < n1.

The ones in here 1 The parking lock 1 shown thus comprises a parking lock wheel 2 firmly connected to a drive train, not shown here, and a 2 Park pawl 5 shown. As in 1 As can be seen here, the parking lock wheel 2 has a large number of teeth 4 and tooth gaps 3 and can rotate about an axis of rotation R. Furthermore, the parking lock according to the first preferred embodiment shown here includes a single ratchet wheel 6 , the ratchet wheel 6 being rotatable about the axis of rotation R relative to the parking lock wheel 2 .

In addition, here the ratchet wheel 6 is coupled to a centrifugal governor 22 , with the centrifugal governor 22 being located in a first receiving area B1 of the ratchet wheel 6 . As in 1 As can be seen here, the centrifugal governor 22 comprises a first mass element 10 and a second mass element 11, with the centrifugal force resulting from the rotation, indicated by a double arrow, moving the first mass element 11 along a first guide pin 8, which is connected here to the parking lock wheel 2 in a rotationally fixed manner, and a second mass element 12 is movable along a second guide pin 9 which is here connected to the parking lock wheel 2 in a rotationally fixed manner. An element implemented here in the form of a spring element 12 generates a counterforce to the centrifugal force.

As in 1 shown, the ratchet wheel 6 also has a first guide groove 13, which is essentially linear in this case, and opposite as in FIG 2 As can be seen, there is a second guide groove 14, with the first guide pin 8 being at an angle (α1) to the first guide groove 13 and the second guide pin 9 being at an angle (α1) to the second guide groove 14. For example, here the first mass element 10 comprises a first guide element facing the guide groove 13 and preferably molded onto the mass element 10 (not visible here, position indicated by a dashed circle), the first guide element being designed to correspond to the guide groove 13 and engaging in the guide groove can, so that when the mass element 10 moves, the ratchet wheel 6 coupled thereto rotates relative to the parking lock wheel 2 .

In terms of an alternative embodiment, the first and the second guide groove can also have an S-course.

Analogous to this, the second mass element 11 here comprises a second guide element (not visible here, position indicated by a dashed circle) facing the guide groove 14 and preferably molded onto the mass element 11, corresponding to the guide groove 14.

As a result, the centrifugal governor 22 is coupled to the ratchet wheel 6 in such a way that the parking lock 1 is dependent on the speed in 1 shown, open position can be brought into the closed position.

As in 1 shown in the open position are the first and second mass members 10; 11 at a first stop A1, in which the first and second mass elements 10; 11 rest directly against a center piece 21. In this open position, an angle (α1) between guide pin 8; 9 and guide groove 13; 14 definable.

Furthermore, in 1 another, formed on the mass element 10, third guide element 26 is shown, which faces away from the first ratchet wheel 6 and is rotated in the opposite direction to the first guide element. In addition, shows 1 a fourth guide element 27 formed integrally with the mass element 11, which faces away from the first ratchet wheel 6 and is arranged rotated in the opposite direction to the second guide element.

From here on out, like reference numerals refer to like components throughout the figures.

In the following shows 2 a top view of the first preferred embodiment of the parking lock 1 with a single ratchet wheel 6 in an open position, in which case the parking pawl wheel 2 has five tooth spaces 3 and the ratchet wheel 6 has five corresponding ratchet wheel tooth spaces 17 . As in 2 additionally evident, by inserting a ratchet tooth 23 of a parking lock pawl 5, which can be pivoted about a pivot axis S, into a recess formed by the flush tooth gap 3 of the parking lock wheel 2 and the ratchet tooth gap 17 of the ratchet wheel 6, the parking lock 1 and the associated drive train can be locked . In addition, 2 Another angle (β1) can be seen, with the tooth gap 3 of the parking lock wheel 2 and the ratchet wheel tooth gap 17 of the ratchet wheel 6 being essentially flush with one another (ie angle (β1) is approximately equal to zero here).

3 shows a top view of the first preferred embodiment of the parking lock 1 with a single ratchet wheel 6 in a closed position, wherein as in FIG 3 shown here the tooth space 3 of the parking lock wheel 2 and a ratchet wheel tooth space 17 of the ratchet wheel 6 is rotated relative to each other. In addition, 2 another angle (β2) can be seen, in which case, as mentioned, the tooth gap 3 of the parking lock wheel 2 and the ratchet wheel tooth gap 17 of the ratchet wheel 6 are rotated relative to each other.

In this closed position, an angle (α2) between guide pin 8; 9 and guide groove 13; 14 definable.

Within the meaning of the present application, the following angular relationship applies: α1−β1=α2+β2.

In the closed position shown here, the current speed n is greater than the upper speed n2, i.e. n > n2, whereby in this closed position the ratchet tooth of the parking lock pawl (not shown here) is not in the position due to the mutually offset tooth gaps 3; 17 reduced or reduced recess can engage or the parking lock 1 does not block. In other words, the recess formed by the tooth gaps and provided for receiving the ratchet tooth of the parking lock pawl is reduced by a first deflection x, as a result of which the latching of the ratchet tooth is prevented.

In the following shows 4 a side view of a second preferred embodiment of the parking lock 1, in which case the parking lock 1 has two ratchet wheels 6; 7, ie a first ratchet wheel 6 and a second ratchet wheel 7 includes. in the in 4 In the open position shown, the tooth gap 3 of the parking lock wheel 2, the first ratchet wheel tooth gap 17 of the first ratchet wheel 6 and the second ratchet wheel tooth gap 19 of the second ratchet wheel 7 are arranged flush with one another, so that a ratchet tooth of a parking pawl, not shown here, fits into the tooth gaps 3; 17; 19 formed recess can engage.

5 shows a side view of the second preferred embodiment of the parking lock 1 with two ratchet wheels 6; 7, ie a first ratchet wheel 6 and a second ratchet wheel 7, in a closed position.

According to this second preferred embodiment, the centrifugal governor 22 is arranged between the two ratchet wheels 6; 7, ie both in the first receiving area B1 of the first ratchet wheel 6 and in a second receiving area B2 of the second ratchet wheel 7 (not visible here).
As in 5 visible here are the tooth space 3 of the parking lock wheel 2, the ratchet wheel tooth space 17 of the first ratchet wheel 6 and the ratchet wheel tooth space 19 of the second ratchet wheel 7 rotated relative to one another.

In particular, here, for example, according to a particularly preferred variant, the parking lock 1 is designed in such a way that the first ratchet wheel 6 and the second ratchet wheel 7 can be rotated in opposite directions for locking and unlocking.

This is in 1 shown, third guide element 26 arranged here corresponding to a third guide groove of the second ratchet wheel 7, while in 1 shown, fourth guide element 27 is arranged here corresponding to a fourth guide groove of the second ratchet wheel 7 .

In other words, the recess formed by the tooth gaps and provided for receiving the ratchet tooth of the parking lock pawl is reduced by both a first deflection x and an opposite deflection y (as indicated by arrows), which prevents the ratchet tooth from latching .

Reference List

1

parking lock

2

parking lock wheel

3

First tooth gap (of the locking teeth of the parking lock gear)

4

First tooth (of the parking lock gear ratchet teeth)

5

parking lock pawl

6

First ratchet wheel

7

Second ratchet wheel

8th

First guide pin

9

Second guide pin

10

First mass element

11

Second mass element

12

spring element (of the centrifugal governor)

13

First guide groove

14

Second guide groove

15

First guide element (corresponding to the first guide groove)

16

Second guide element (corresponding to the second guide groove)

17

First ratchet tooth gap (of the first ratchet wheel)

18

First ratchet tooth (of the first ratchet wheel)

19

Second ratchet tooth gap (of the second ratchet wheel)

20

Second ratchet tooth (of the second ratchet wheel)

21

centerpiece

22

centrifugal governor

23

ratchet tooth (of the parking lock pawl)

24

Third guide groove (of the second ratchet wheel)

25

Fourth guide groove (of the second ratchet wheel)

26

Third guide element (corresponding to the third guide groove)

27

Fourth guide element (corresponding to the fourth guide groove)

α1; α2

Angle (between guide pin and guide groove)

β1; β2

Angle (between open and closed position)

A1

First stop (of the centrifugal governor)

A2

Second stop (of the centrifugal governor)

B1

First receiving area (of the first ratchet wheel)

B2

Second recording area (of the second ratchet wheel)

R

axis of rotation (of the parking lock wheel)

S

pivot axis (of the parking lock pawl)

x

First deflection (of the first ratchet wheel)

y

Second deflection (of the second ratchet wheel)

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102010042917 A1 [0008, 0012]
• DE 102017212093 A1 [0011, 0012]

Claims (5)

Parking lock (1) comprising at least one parking lock wheel (2) firmly connected to a drive train and a parking lock pawl (5) that can be brought into operative connection with the parking lock wheel (2) for locking and unlocking the parking lock (1), the parking lock wheel (2) having a plurality of teeth (4) and tooth gaps (3) and wherein the parking lock pawl (5) includes a ratchet tooth (23), and wherein the parking lock wheel (2) has a rotational movement about a rotation axis (R) and the parking lock pawl (5) has a pivoting movement about a pivot axis (S), characterized in that the parking lock (1) comprises at least one ratchet wheel (6; 7) which can be rotated about the axis of rotation (R) relative to the parking lock wheel (2), the parking lock (1) being able to be brought into an open position , in which a tooth space (3) of the parking lock wheel (2) and a ratchet wheel tooth space (17; 19) of the at least one ratchet wheel (6; 7) is flush, to achieve locking of the parking lock (1) and the associated drive train angs, wherein the parking lock (1) can be brought into a closed position in which a tooth gap (3) of the parking lock wheel (2) and a ratchet wheel tooth gap (17; 19) of the at least one ratchet wheel (6; 7) is twisted relative to one another to prevent the parking lock (1) from locking, and wherein the parking lock (1) also has a centrifugal governor (22 ) comprises, and wherein the centrifugal governor (22) is designed and coupled to the at least one ratchet wheel (6; 7) in such a way that the parking lock (1) can be brought from the open position into the closed position as a function of the speed. Parking lock (1) after Claim 1 , characterized in that the centrifugal force regulator (22) comprises a first and second mass element (10; 11) movable by means of centrifugal force along a first and second guide pin (8; 9) and an element generating a counterforce, in particular a spring element (12), comprises, wherein the at least one ratchet wheel (6; 7) further comprises first and second guide grooves (13; 14) standing at an angle (α) to the guide pins (8; 9), wherein the first and second mass element (10; 11 ) comprises a respective first and second guide element (15; 16) engaging in the guide grooves (13; 14) and thereby the centrifugal governor (22) is coupled to the at least one ratchet wheel (6; 7) in such a way that the parking lock ( 1) can be brought from the open position to the closed position depending on the speed. Parking lock (1) after Claim 1 , characterized in that the parking lock (1) comprises a first ratchet wheel (6) and a second ratchet wheel (7), wherein the parking lock (1) is designed such that the first ratchet wheel (6) and the second ratchet wheel (7) can be twisted in opposite directions to lock and unlock. Parking lock (1) according to one of the preceding patent claims, characterized in that in an open position the first and second guide groove (13; 14) of the at least one ratchet wheel (6; 7) are at an angle (α1) to the guide pins (8; 9 ) and with a flush tooth gap (3) and ratchet tooth gap (17), an angle (β1) can be defined; and in a closed or closing position an angle (α2) and an angle (β2) can be defined; and where: α1 - β1 = α2 + β2. Parking lock (1) according to one of the preceding patent claims, characterized in that when the parking lock (1) is in an open position, the current speed n is less than the lower speed n1, ie n<n1; while in a closed position of the parking lock (1), the current speed n is greater than the upper speed n2, ie n>n2; where n1 is in a preferred speed range of 150 to 180 rpm, while n2 is in a preferred speed range of 400 to 450 rpm.

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