DE102009035348A1 - Parking lock device for automatic or automated motor vehicle transmission, has slide valve provided between relief valve and hydraulic cylinder in pressure pipe and servo-controlled by shift valve - Google Patents

Abstract

The device (1) has a locking element (2) coupled with a hydraulic cylinder (3) and/or a piston (4) such that the element is engageable in a pressure-free condition of the cylinder by a spring element (9) or a compression spring, and a motor vehicle transmission is blockable and disengageable by an application of pressure of the cylinder. The pressure is adjustable with a relief valve (12) i.e. directly steered regulating valve, by a pressure pipe (11). A slide valve (13) is provided between the relief valve and the cylinder in the pipe, and is servo-controlled by a shift valve (14).

Description

The The invention relates to a parking brake device for a automatic or automated motor vehicle transmission, with at least a locking member and at least one hydraulic cylinder, wherein the hydraulic cylinder and / or its piston with a spring element, vzw. is spring-loaded with a compression spring in a direction of adjustment, wherein the motor vehicle transmission is blockable by means of the locking member and wherein the locking member is operatively operative with the hydraulic cylinder and / or is coupled to the piston, so that in the pressureless state the hydraulic cylinder by means of the spring element, vzw. the compression spring the locking member engageable and the motor vehicle transmission is blockable and by pressurizing the hydraulic cylinder the locking member is disengaged, wherein the pressure in the hydraulic cylinder via a pressure line with a safety valve is adjustable.

A Parking lock device for an automatic or automated Motor vehicle transmission prevents the unwanted rolling away of the vehicle by a secure locking of the motor vehicle transmission. By blocking of the motor vehicle transmission are the driven wheels of the motor vehicle secured against rotation. The parking lock device points to vzw. a parking lock gear od. Like. On, the rotation with an output of the motor vehicle transmission is connected. Further points the parking brake device on a locking member which in the parking lock gear od. Like. Intervene and can block the parking lock gear. If the locking member blocks the motor vehicle transmission is the Parking lock engaged or engaged the locking member.

Of the Driver of a motor vehicle can vzw. over an exterior Circuit, in particular a selector lever different Select driving steps, for example the driving steps P, R, N, D. In a so-called "shift-by-wire" circuit the selected gear is via a sensor on the outer mechanical circuit vzw. so detected at the selector lever and via a data connection eg. Via a bus system, vzw. via a CAN bus (CAN Controller Area Network) sent to a transmission control device. The transmission control device then sets the appropriate one by the user Selected circuits using the selector lever (eg P, R, N, D) via a hydraulic control within of the gearbox.

The Locking member can via a spring-loaded hydraulic cylinder be operated. The hydraulic cylinder is vzw. with a Spring loaded spring. The locking member blocked when inserted Parking lock the motor vehicle transmission. The locking member is functional effectively acted upon by the hydraulic cylinder. When the hydraulic cylinder is in a depressurized state is by means of the compression spring the locking member engaged or the parking lock engaged and the motor vehicle transmission therefore blocked. By pressurizing of the hydraulic cylinder, the locking member is disengaged and the blockage of the motor vehicle transmission is canceled or the parking brake is designed.

• F1: Die Parksperre muss durch Druckbeaufschlagung des Hydraulikzylinders auslegbar sein.
• F2: Die Parksperre muss über Druckentlastung des Hydraulikzylinders einlegbar sein, so dass das Federelement entsprechend funktional wirksam auf das Sperrglied wirkt.
• F3: Die Parksperre sollte offen gehalten werden im Fahrzustand N, wenn der Motor ausgeschaltet ist, bspw. falls das Kraftfahrzeug in einer Waschstraße gewaschen werden soll.

In the design of the parking brake device, the following functions must be considered:

• F1: The parking brake must be able to be extended by pressurizing the hydraulic cylinder.
• F2: The parking brake must be able to be inserted via pressure relief of the hydraulic cylinder, so that the spring element acts correspondingly functionally effective on the locking member.
• F3: The parking lock should be kept open in driving state N when the engine is off, for example, if the vehicle is to be washed in a car wash.

• S1: Die Parksperre darf nicht ungewollt bei ausgeschaltetem Motor in der Wählhebelposition N (Neutral, Leerlauf) einrücken.
• S2: Bei einer hydraulischen Fehlfunktion während des Fahrens, d. h. wenn der an dem Hydraulikzylinder anliegende Druck einbricht, soll verhindert werden, dass die Parksperre ungewollt einrastet.
• S3: Beim Einbruch der Bordnetzspannung muss das Einlegen der Parksperre zumindest solange verhindert werden, bis das Fahrzeug steht bzw. eine geringe Geschwindigkeit aufweist.
• S4: Beim Ausfall sämtlicher Hilfsenergien – insbesondere der elektrischen und hydraulischen Hilfsenergien – muss das Fahrzeug in einen gesicherten Zustand übergehen, d. h. die Parksperre muss eingelegt sein.

Furthermore, the following aspects in the design of the parking brake device should also be considered:

• S1: Do not accidentally engage the parking brake with the engine off in selector lever position N (neutral, neutral).
• S2: In the event of a hydraulic malfunction during driving, ie when the pressure applied to the hydraulic cylinder collapses, the parking brake should be locked inadvertently.
• S3: When breaking in the vehicle electrical system voltage, the parking brake must be engaged at least until the vehicle is stationary or has a low speed.
• S4: In case of failure of all auxiliary power - especially the electrical and hydraulic auxiliary power - the vehicle must go into a secure state, ie the parking brake must be engaged.

Around a safe stopping of the vehicle from high speed when Failure of all auxiliary power to ensure is additionally the parking brake device or the parking lock control be interpreted that above a safe limit speed the insertion of the parking brake is rejected or prevented and only when falling below this limit speed, the parking brake is inserted.

In the prior art, parking lock devices of completely different design are now known:
From the EP 1 099 067 B1 a parking brake device with a hydraulic cylinder is known, wherein the hydraulic cylinder is spring-loaded with a compression spring. When the hydraulic pressure is switched off, the parking lock remains disengaged for a long time, as a result that the hydraulic cylinder is held by means of a lock, which is actuated by energizing an electromagnet. By energizing the electromagnet, the bolt locks the hydraulic cylinder. When energizing the electromagnet are ball-like elements which are mounted in a receptacle of the piston, radially displaced in a conical outer region, until they are in engagement with a recess in the housing and then a movement of the piston is blocked.

From the DE 198 20 920 B4 a parking brake device with a locking member and a hydraulic cylinder is known. The hydraulic cylinder is held at an unlocked parking lock by an electromagnetically actuated locking mechanism.

From the DE 10 2004 043 344 A1 a parking brake device with a hydraulic cylinder is known. The hydraulic cylinder has a piston rod, which is durable in a designed parking lock via a locking device. The parking lock device is designed with a Parksperrenentriegelung, which can only be activated by two independent operating actuators.

From the DE 43 22 523 A1 a parking brake device with a hydraulic cylinder is known, wherein the hydraulic cylinder is coupled with unlocked parking lock by a Bowden cable with a gear selector so that the engagement of the parking brake is prevented when the selector is not the gear "P" is inserted.

From the DE 10 2005 049 177 A1 a parking brake device with a hydraulic cylinder is known. The parking lock is held by a holding device in a released position. The holding device has at least one filled with an electrorheological fluid container, a piston and a coil. When the coil is energized, the electrorheological fluid solidifies and the parking lock is blocked.

From the DE 102 45 386 A1 a parking brake device for an automatic transmission or an automated manual transmission is known. The parking brake device has a parking lock or a locking member which is inserted via a spring accumulator and is designed hydraulically or pneumatically via a pressurization of a hydraulic cylinder. The parking brake device further comprises a pump. The pump supplies the hydraulic cylinder with pressure after switching off a drive motor, so that the parking lock remains in the unlocked position even when the drive motor is switched off.

From the DE 41 27 991 C2 a parking brake device with a hydraulic cylinder is known. The hydraulic cylinder is spring loaded with a compression spring. In a pressure line leading to the hydraulic cylinder, a solenoid valve and a shut-off valve is arranged. Between the two valves, a pressure accumulator is provided, whereby the parking brake can be kept open when the drive motor for a limited period of time.

All The above publications are concerned with the problem the hydraulic cylinder with unlocked parking lock in "the open position "or pressurized to keep, especially in the event that a pressure drop in the system is to be feared, if the auxiliary electric power eliminated.

Of the Invention is therefore the object of the aforementioned Design and develop parking brake device such so that when a disengaged locking member of the hydraulic cylinder is held in the pressurized position, in particular even in the event that the vehicle electrical system voltage during of driving breaks.

The previously indicated task Will now for the parking brake device solved in that in the pressure line between the safety valve and the hydraulic cylinder, a slide valve is provided, wherein the slide valve is pilot-controlled via a switching valve. The requirements mentioned above are thus essentially fulfilled by a purely hydraulic solution. Especially the pressure line is hydraulically openable and separable. The switching valve is open in the de-energized state. As long as a hydraulic Pilot pressure applied to the de-energized switching valve, the slide valve is closed. In the de-energized state, therefore, the slide valve separates the hydraulic cylinder hydraulically and the pressure in the hydraulic cylinder is maintained, so that when breaking the vehicle electrical system voltage, the engagement of the parking brake or the insertion / engagement of the locking member at least as long is prevented until the vehicle is at a lower speed has taken. When the hydraulic pressure at the de-energized switching valve and thus at the slide valve additionally omitted, then the gate valve opens and the pressure in the cylinder can be degraded, whereby the parking lock or the locking member engages. As a result, the insertion of the parking brake or the locking member is at least is prevented until the hydraulic pressure is eliminated and the vehicle is at a lower speed Has. In the energized state of the switching valve is over the slide valve a hydraulic connection between the safety valve and the hydraulic cylinder produced. The initially described Disadvantages are therefore avoided and achieved corresponding advantages.

There are now a variety of ways to design and develop the parking brake device according to the invention in an advantageous manner. For this purpose, reference may first be made to the claims subordinate to claim 1. In the following, a preferred embodiment of the invention will now be explained in more detail with reference to the drawing and the associated description. In the drawing shows the only figure

1 in a schematic representation of a parking brake device according to the invention,

2a a further embodiment of a hydraulic-mechanical locking including the hydraulic circuit and the components arranged here, as well as

2 B the in 2a illustrated hydraulic cylinder in an enlarged schematic representation of the page.

In the 1 is a parking brake device according to the invention 1 clearly visible.

The parking lock device 1 is suitable for use in conjunction with an automatic or automated motor vehicle transmission (not shown in detail here).

at the motor vehicle transmission is vzw. to an electric controlled motor vehicle transmission. Such switching methods are For example, referred to as "shift-by-wire" method. This means that the speed levels (eg P, R, N, D) are over an external circuit vzw. by one from the driver operable selector lever (not shown) are selected, not mechanically via a Bowden cable to a hydraulic Control (not shown) are transmitted. In a "shift-by-wire" method is the driver's request via a sensor (not shown) at the outer circuit, for example. At the position a selector lever, detected and via a data connection (not shown) to a transmission control unit (not shown) Posted. The transmission control unit then sets the appropriate Actions / circuits via a hydraulic control in the Gearbox around.

The parking lock device 1 prevents the unintentional rolling away of a motor vehicle by non-rotatable locking of the motor vehicle transmission, so that the driven wheels of the motor vehicle are secured against rotation. The parking lock device 1 has a locking member 2 on. Furthermore, the parking brake device 1 an unillustrated Parksperrenrad on, wherein the Parksperrenrad vzw. rotatably connected to the output of the motor vehicle transmission. When the driver brings the selector lever not shown in the position P, the locking member 2 directly or possibly brought about further mechanical links with the Parksperrenrad engaged, so that the locking member 2 the parking lock wheel is blocked by the corresponding insertion / engagement. As a result, the motor vehicle transmission and thus the drive wheels of the motor vehicle is blocked against rotation.

Vzw. has the locking member 2 no direct mechanical connection with the selector lever. The locking member 2 is functionally effective with a hydraulic cylinder 3 connected, in particular vzw. functionally effective with the piston 4 of the hydraulic cylinder 3 connected. The hydraulic cylinder 3 therefore has a piston 4 on, with the piston 4 via a piston rod 5 with a swivel lever 6 connected is. The piston rod 5 engages at one end of the pivot lever 6 on, with the other end of the pivot lever 6 with an operating rod 7 is connected, in turn, on the locking member 2 attacks. The swivel lever 6 is about a pivot axis 8th rotatably mounted. The hydraulic cylinder 3 is with a spring element 9 , vzw. with a compression spring 9a between the housing part de 3 and the piston 4 is effectively arranged, spring loaded. In particular, the piston 4 of the hydraulic cylinder 3 therefore with the compression spring 9a spring-loaded in a certain actuating direction. Furthermore, another pressure spring 10 provided, which also on the locking member 2 acts. Also conceivable is a differently configured mechanism between the actuating cylinder 3 and the locking member 2 , this depends on the particular application.

The locking member 2 blocks the motor vehicle transmission when engaged in the parking lock gear, ie with engaged parking brake. The locking member 2 is functionally effective from the hydraulic cylinder 3 acted upon, so that the hydraulic cylinder 3 in depressurized state by means of the compression spring 9a the locking member 2 inserted / indented. By pressurizing the hydraulic cylinder 3 is the locking member 2 disengaged. The force of the hydraulic cylinder 3 is over the pivot lever 6 transfer. The pressurization of the hydraulic cylinder 3 acts against the force of the compression spring 9a , The pressurization of the hydraulic cylinder 3 also acts against another pressure spring 10 , the vzw. on the locking member 2 attacks.

The pressure in the hydraulic cylinder 3 , in particular in the working space of the hydraulic cylinder, which is not specified here 3 , is via a pressure line 11 provided. The pressure in the hydraulic cylinder 3 is over the pressure line 11 with a safety valve 12 adjustable / controllable. By means of the safety valve 12 is the pressure line 11 with a swamp 16 connectable. The safety valve 12 is vzw. designed as a control valve, but can also be designed as a switching valve. The safety valve 12 is vzw. designed as a directly controlled control valve. The Si safety valve 12 is designed here as a 3/3-way valve with blocking means position. The safety valve 12 is electric, vzw. formed electromagnetically operable. The safety valve 12 has a provision in the swamp 16 open position on. The provision is partially designed as a spring return. Furthermore, vzw. a possibly pressure-reduced feedback line 19 provided for the provision. When the hydraulic cylinder side of the safety valve 12 a pressure in the pressure line 11 is applied and the safety valve 12 is not electrically actuated, the pressure on the feedback line 19 on the slide (not shown in detail) of the safety valve 12 fed back, so that the applied feedback pressure the safety valve 12 to the swamp 16 opens.

The safety valve 12 used for regulated pressurization or regulated pressure relief of the hydraulic cylinder 3 , Through the safety valve 12 is the parking brake or the locking member 2 via pressurization of the hydraulic cylinder 3 interpretable or disengageable. About pressure relief of the hydraulic cylinder 3 is the parking brake or the locking member 2 insertable or engageable, so that the compression spring 9a the pivot lever 6 so pivots, causing the locking member 2 engages. The functions F1, F2 are therefore fulfilled.

The aforementioned disadvantages are now avoided by the fact that in the pressure line 11 between the safety valve 12 and the hydraulic cylinder 3 a slide valve 13 is provided, wherein the slide valve 13 via a switching valve 14 is pre-controlled. In the event that the vehicle electrical system voltage breaks during driving, is at a disengaged locking member 2 the hydraulic cylinder 3 held in the pressurized position that in the pressure line 11 between the safety valve 12 and the hydraulic cylinder 3 the slide valve 13 is provided, wherein the slide valve 13 via the switching valve 14 hydraulically piloted. The slide valve 13 is vzw. designed as a slide switch. The slide valve 13 is via the switching valve 14 so pre-controlled that in the de-energized state of the switching valve 14 the slide valve 13 is closed at an applied pilot pressure. In the de-energized state therefore separates or blocks the slide valve 13 the hydraulic cylinder 3 hydraulically, so that when breaking the vehicle electrical system voltage, the engagement of the parking brake is at least as long prevented until the vehicle is stationary or has a low speed.

The switching valve 14 is open in the de-energized state. As long as a hydraulic pilot pressure over the open switching valve 14 and over the supply line 17 on the slide valve 13 acts, is the gate valve 13 closed. The slide valve 13 is disabled as long as a pilot pressure at the gate valve 13 rests, so that the hydraulic cylinder 3 the applied pressure via the pressure line 11 not in the swamp 16 can degrade. The pilot pressure at the switching valve 14 or on the slide of the slide valve 13 is over a throttle 18 opposite the pressure in the pressure line 11 reduced.

The switching valve 14 is closed when energized. If no pilot pressure via the supply line 17 on the slide valve 13 is applied, is the slide valve 13 in the energized state of the switching valve 14 open. The slide valve 13 then has a provision in its passage position. The slide valve 13 is designed as a pressure-operated 2/2-way valve with spring return into the passage position. The switching valve 14 is designed as an electrically, vzw electromagnetically actuated 2/2-way valve with spring return into the passage position.

This has the advantage that in the energized state via the slide valve 13 a hydraulic connection between the safety valve 12 and the hydraulic cylinder 3 can be produced. In the de-energized state separates the slide valve 13 however the pressure line 11 hydraulically, so that when breaking the vehicle electrical system voltage, the engagement of the parking brake or the locking member 2 prevented for the time being. The aforementioned aspect S3 is therefore satisfied.

When the engine of the vehicle is stationary or the oil pump driven by the prime mover (engine) has taken on a lower capacity at a lower speed of the vehicle, the hydraulic pressure in the pressure line also breaks 11 and in the supply line 17 one. When the hydraulic pressure at the switching valve 14 and thus the pilot pressure at the slide valve 13 in addition falls away, then opens the slide valve 13 and the pressure in the hydraulic cylinder 3 can be removed, causing the parking brake or the locking member 2 engages. As a result, the engagement of the parking brake or the locking member 2 is at least as long prevented until the hydraulic pressure is eliminated and the engine of the vehicle is stationary or the vehicle has taken a lower speed. When all auxiliary powers are eliminated including the pilot pressure via the switching valve 14 , the gate valve goes 13 in the in the 1 illustrated open state over.

Between the hydraulic cylinder 3 and the safety valve 12 is a parking lock seat valve 15 in the pressure line 11 intended. The parking lock seat valve 15 is vzw. between the slide valve 13 and the hydraulic cylinder 3 in the pressure line 11 arranged. The parking lock seat valve 15 is electric, vzw. Electromagnetically actuated. The park lock seat valve 15 has a spring return in the passage position. The parking lock seat valve 15 is vzw. designed as a 2/2-way valve or as an electrically unlockable ball seat valve. When the pressure in the hydraulic cylinder 3 is to maintain the parking lock seat valve 15 only with electrical energy, so closed by energization. Through the parking lock seat valve 15 is solely by electrical power supply the blocking member 2 durable in the disengaged position. Essential feature of the park barrier seat valve 15 is a leak-free design or a virtually leak-free design. Further, the piston 4 vzw. also essentially leak-free in the hydraulic cylinder 3 sealed, the seal on the piston and the low-leakage / -freie parking lock seat valve in connection with the compression spring 9 how an accumulator act. The entire system is designed leak-free mainly due to the components used here.

Through the parking lock seat valve 15 can the locking member 2 be kept open only by electrical auxiliary energy without supply of auxiliary hydraulic energy. As a result, the locking member 2 or the parking brake in state N are kept open. For example. when the drive motor has been turned off and the motor vehicle is to be moved through a washing line, the pressure in the hydraulic cylinder 3 by closing the parking lock seat valve 15 and maintained by the leak-free training, so that the locking member 2 does not interfere. The function F3 and the aspect S1 are therefore satisfied.

Furthermore, by the parking lock seat valve 15 prevents a hydraulic malfunction during driving, for example. A pressure drop, the parking brake or the locking member 2 unintentionally engages. When the drive motor is switched off and at the same time in the energized state of the parking lock seat valve 15 is through the parking lock seat valve 15 prevents the locking member 2 engages. Aspect S2 is therefore fulfilled.

In the event of failure of all auxiliary power, the parking lock seat valve 15 opened by the spring return and the hydraulic cylinder 3 inevitably on the parking lock seat valve 15 , the open slide valve 13 and the opened safety valve 12 in the swamp 16 relieved of pressure, as shown in the figure. Aspect S4 is therefore satisfied. The disadvantages mentioned above are therefore avoided and achieved corresponding advantages.

Deviating from 1 is now in the 2a respectively. 2 B another, but now hydraulic-mechanical solution realized.

Good to recognize in 2a here is the parking lock device 1 with the locking member 2 and the hydraulic cylinder 3 , Similar components as in the 1 are also referred to similarly, in particular the piston 4 , the piston rod 5 , the pivot lever 6 , the confirmation bar 7 , the pivot axis 8th and a compression spring 9 , which is arranged here between the housing of the hydraulic cylinder 3 and the pivot lever 6 , Finally, there is a compression spring 10 similar to in 1 intended.

Also in the here in 2a shown hydraulic circuit are corresponding unspecified here pressure lines, but in particular also a safety valve 12 and a parking lock seat valve 15 provided, with the help of a unspecified here pressure chamber in the hydraulic cylinder 3 can be acted upon, in particular to the piston 4 who is here vzw. designed as a hollow cylinder, move accordingly / move accordingly.

At the here in 2a illustrated embodiment is now for the piston 4 a guide element 20 provided, which is formed substantially T-shaped and hydraulically movable blocking elements 21 has, which are rod-shaped and in unspecified grooves on the outer inner circumference of the piston 4 can intervene.

To block / lock the piston 4 can these blocking elements 21 be pressurized accordingly, namely via a corresponding unspecified here pressure line or a switching valve 22 , as well as out 2a seen.

As the 2 B shows, in a corresponding pressurization in the guide element 20 radially mounted blocking elements 21 moved accordingly, in particular be moved radially outwards, so that these in unspecified recesses on the inner circumference of the piston 4 intervention.

With this here in the 2a and 2 B illustrated embodiment is therefore a hydraulic / mechanical solution for locking or for the realization of a parking brake device 1 shown.

Notwithstanding the in 1 described solution is in the in the 2a and 2 B described solution now in the hydraulic cylinder 3 provided a mechanical lock. In combination with the switching valve 22 This locking takes over the function of in 1 illustrated slide valve 13 , The functions of the safety valve 12 or parking lock seat valve 15 essentially correspond to the description of the 1 ,

The 2 B shows the parking lock device 1 in an enlarged view in the position "designed", here are the blocking elements 21 moved radially inward. The locking pin-shaped blocking elements 21 can - as already mentioned - in corresponding unspecified grooves on the inside of the piston 4 intervention. Here are the blocking elements 21 operated via the switching valve 22 , Takes the hydraulic cylinder 3 the end position shown here, so can via the switching valve 22 in the de-energized state, the system pressure of the hydraulic control on the bottom of the blocking elements 21 be directed. The pin-shaped blocking elements 21 then drive radially outward and enter the "Rastierungsnuten" of the piston 4 of the hydraulic cylinder 3 one, so that the position of the piston 4 positively held in this position. To unlock the piston 4 can via the switching valve 22 the barrier pressure will be relieved and the piston 4 can, driven by the compression spring 9 be extended so that the parking lock can engage or be inserted. Also with the in 2a and 2 B Therefore, corresponding advantages are achieved and the aforementioned disadvantages avoided.

LIST OF REFERENCE NUMBERS

1

Parking lock device

2

locking member

3

hydraulic cylinders

4

piston

5

piston rod

6

pivoting lever

7

actuating rod

8th

swivel axis

9

compression spring

10

compression spring

11

pressure line

12

safety valve

13

spool valve

14

switching valve

15

Parking lock valve seat

16

swamp

17

feed

18

throttle

19

Feedback line

20

guide element

21

blocking element

22

switching valve

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1099067 B1 [0008]
• - DE 19820920 B4 [0009]
• - DE 102004043344 A1 [0010]
• - DE 4322523 A1 [0011]
• - DE 102005049177 A1 [0012]
• DE 10245386 A1 [0013]
• - DE 4127991 C2 [0014]

Claims (11)

Parking lock device ( 1 ) for an automatic or automated motor vehicle transmission, with at least one locking member ( 2 ) and at least one hydraulic cylinder ( 3 ), wherein the hydraulic cylinder ( 3 ) and / or its piston ( 4 ) with a spring element ( 9 ), vzw. with a compression spring ( 9a ) is spring-loaded in a setting direction, wherein the motor vehicle transmission by means of the locking member ( 2 ) is blockable and wherein the locking member ( 2 ) functionally effective with the hydraulic cylinder ( 3 ) and / or with the piston ( 4 ) is coupled, so that in the pressureless state of the hydraulic cylinder ( 3 ) by means of the spring element ( 9 ), vzw. the compression spring ( 9a ) the locking member ( 2 ) engageable and the motor vehicle transmission is blocked and by pressurizing the hydraulic cylinder ( 3 ) the locking member ( 2 ) is disengageable, wherein the pressure in the hydraulic cylinder ( 3 ) via a pressure line ( 11 ) with a safety valve ( 12 ) is controllable, characterized in that in the pressure line ( 11 ) between the safety valve ( 12 ) and the hydraulic cylinder ( 3 ) a slide valve ( 13 ) is provided, wherein the slide valve ( 13 ) via a switching valve ( 14 ) is pilot-controlled. Parking brake device according to claim 1, characterized in that between the hydraulic cylinder ( 3 ) and the safety valve ( 12 ) an electrically operated parking lock seat valve ( 15 ) in the pressure line ( 11 ) is provided. Parking brake device according to claim 1 or 2, characterized in that the parking lock seat valve ( 15 ) in the re-energized state has a provision in its passage position. Parking brake device according to one of the preceding claims, characterized in that the safety valve ( 12 ) as vzw. directly controlled control valve is formed. Parking brake device according to one of the preceding claims, characterized in that in the energized state of the switching valve ( 14 ) a hydraulic connection between the safety valve ( 12 ) and the hydraulic cylinder ( 3 ), in particular the downstream parking lock seat valve ( 15 ) is realized. Parking brake device according to one of the preceding claims, characterized in that in the de-energized state of the switching valve ( 14 ) of the hydraulic cylinders ( 3 ) by means of the slide valve ( 13 ) hydraulically from the safety valve ( 12 ) as long as a hydraulic pilot pressure at the then opened slide valve ( 13 ) is present. Parking brake device according to one of the preceding claims, characterized in that by the hydraulic separation of the hydraulic cylinder ( 3 ) from the safety valve ( 12 ) in the de-energized state of the switching valve ( 14 ) at the onset of a vehicle electrical system voltage, the insertion / engagement of the locking member ( 2 ) is preventable. Parking brake device according to one of the preceding claims, characterized in that the parking lock seat valve ( 15 ) is leak-free. Parking brake device according to one of the preceding claims, characterized in that the hydraulic cylinder ( 3 ) a guided and thereby hydraulically sealed piston ( 4 ) having. Parking brake device according to one of the preceding claims, characterized in that the slide valve ( 13 ) as a pressure-operated directional control valve with provision, vzw. a spring return is formed in the passage position. Parking brake device according to one of the preceding claims, characterized in that the switching valve ( 14 ) as electromagnetically actuated 2/2-way valve with provision, vzw. a spring return is formed in the passage position.

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