DE102018003749A1 - Parking lock module for actuating a parking brake in a motor vehicle - Google Patents

Abstract

A parking brake module (10) has a housing (30) in which a with a piston rod (42) operatively connected piston (40) is received, which is biased in a locking direction (S) via a piston spring (44) in a locking position, in which it can be fixed relative to the housing by means of a locking device (46). Furthermore, the piston can be pressurized via a pressure chamber (48) in an unlocking direction (E) opposite to the blocking direction in order to assume an unlocking position when the locking device is released, counter to the piston spring force. On the piston rod, an actuating element (26) is slidably disposed, which is biased by a piston rod spring (50) relative to the piston rod in the reverse direction to a stop (52) on the piston rod and which with a piston movement in the unlocked position on the stop in the unlocking is movable. For pressure decoupling of piston rod and piston, the piston spring engages the piston via a pressure piece (62), which is displaceable by means of the piston rod against the piston spring force relative to the piston in the unlocking direction.

Description

TECHNICAL AREA

The invention relates to a parking brake module for actuating a parking brake in a motor vehicle, according to the preamble of claim 1. In particular, the invention relates to a parking lock module, as they have recently in motor vehicles with hybrid transmissions and modern transmissions with automatic character (automated manual transmissions ) are widely used in the automotive industry.

STATE OF THE ART

Parking locks are required in particular when a self-locking effect of the drive (motor) for holding the motor vehicle can not be used. A blocking of the drive train is then usually via a rotatably mounted on an output shaft of the transmission, a toothed exhibiting Parksperrenrad which can be positively locked by means of a pivotable mounted on a parallel axis parking pawl on the teeth, the parking pawl against the force of a return spring has to be pivoted, which biases the parking pawl away from the parking lock gear in an unlocked position.

For this purpose, in addition to electrically electro-hydraulically or hydraulically operated parking brake actuators are used, which serve to generate a linear movement, via which an actuating element, for example. in the form of a cam or a cone against the parking pawl is movable to pivot it. To ensure that the parking brake prevents rolling of the motor vehicle even when the parking pawl when pressing against a tooth of the parking lock gear comes to rest without coming into positive engagement with the teeth, can also be provided on the actuator energy storage (Nachrückfeder), the in the case of a rolling of the motor vehicle on the actuating element, the parking pawl moves behind, so that it comes into engagement with the teeth of the parking lock gear. In addition, it is usually necessary to ensure that the actuator is locked in its respective operating position with respect to the parking pawl - holding the park pawl pivoted into engagement with the parking lock pawl or releasing the parking pawl - without applying energy (electricity or pressure) and a Emergency operation is possible, which allows an insert of the parking brake in case of failure of the actuator.

In the prior art, there is no lack of proposals to implement these functions integrated in a parking brake module for actuating a parking brake in a motor vehicle. Such a parking brake module, for example, discloses the preamble of claim 1 forming document DE 10 2015 008 709 A1 , According to this prior art, the parking brake module has a pressure chamber housing in which a piston element is received as part of an actuating mechanism. On the piston member, an actuator is articulated in the form of a shift rod. The along a displacement axis of the pressure chamber housing longitudinally displaceable piston member is biased in a Parksperreneinlegerichtung via a piston spring with a spring force in a locking position in which it can be set by means of a locking unit selectively opposite the pressure chamber housing. Furthermore, the piston element can be pressurized via a hydraulic pressure chamber in the pressure chamber housing in a Parksperreneinlegerichtung opposite Parksperrenauslegerichtung to take an unlocked position against the spring force of the piston spring with dissolved detent unit, in which the piston element is again fixed by means of the locking unit with respect to the pressure chamber housing.

Here, an actuating cone is arranged axially displaceably on the shift rod, more precisely on the end facing away from the piston element, which is biased by means of a spring element against the shift rod in the parking lock inserting on a provided on the shift rod stop. In a movement of the piston member in the unlocked position of the actuating cone can thus be moved over the stop in the parking brake direction. The actuating cone has an actuating bevel, which can be brought into contact with a pressure chamber housing solid cone guide element in the form of a metallic support plate, so that the actuating slope is supported at a directed over the piston member longitudinal movement of the shift rod on an alignment bevel of the support plate and thereby under deflection of the shift rod relative to the Piston element causes a movement of the actuating cone in a transverse direction to the parking brake, ie to actuate its blocking element (parking pawl).

In this prior art, furthermore, the respective position of the piston element with respect to the pressure chamber housing can be detected by means of a sensor arrangement which has a stationary relative to the pressure chamber housing displacement sensor and outside the pressure chamber housing a permanent magnet which is axially fixedly coupled to the piston member via a magnet holder to a movement the piston member detectable to follow via the displacement sensor.

The previously known parking lock module further comprises a fastening element in the form of a screw which is screwed into the piston element in order to firmly connect the magnet holder to the piston element. This fastener also serves to connect the piston element and the shift rod in the Parksperreneinlegerichtung motion technology with each other. For this purpose, the fastener on a provided for contacting the shift rod contact surface, while the shift rod has a provided for contacting the fastener contact surface which is formed on a recorded in the piston member with axial play between the fastener and an inner collar of the piston element shift rod head.

The aforementioned axial play ensures a certain angular mobility of the shift rod relative to the piston element. About the facing contact surfaces on the fastener and the shift rod, the piston element is able to push the shift rod in the parking lock insert direction. In contrast, in the parking lock cantilever direction, the piston element can pull the shift rod over the inner collar of the piston element that can be brought into contact with the shift rod head.

A disadvantage of this state of the art is the fact that in the case of attacking on the shift rod abusive forces in the Parksperrenauslegerichtung these forces can penetrate the piston element and thus possibly also on the locking unit, so that there is a risk that these or adjacent components Get damaged. Such abuse forces can e.g. occur when laying out the parking lock on a slope. Here, the actuating cone of the parking brake module between the support plate and locking element (parking pawl) of the parking brake is strongly braced, so that when pulling out the actuating cone high friction forces must be overcome. At a certain pull the Betätigungskonus comes then suddenly free and is greatly accelerated in the Parksperrenauslegerichtung; As a result, there is a setting of the spring element on the shift rod and a shock on the shift rod in the direction of the piston element. Corresponding abusive forces may possibly occur even if the parking lock is prematurely inserted, when a "ratchet" of the locking element (parking pawl) over the teeth of the parking lock gear occurs when the vehicle is rolling and the parking brake wheel is still rotating.

TASK

The invention has for its object to provide a simple trained parking brake module for actuating a parking brake in a motor vehicle, which avoids the above disadvantages and which is optimized over the described prior art, in particular with regard to a damage-free operation.

PRESENTATION OF THE INVENTION

This object is achieved by a parking lock module for actuating a parking lock in a motor vehicle having the features of patent claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

In a parking brake module for actuating a parking brake in a motor vehicle having a housing in which a piston operatively connected to a piston rod is received, which is biased in a locking direction via a piston spring with a spring force into a locking position in which it by means of a locking device optionally can be fixed relative to the housing, and which can be pressurized via a pressure chamber in an opposite direction to the reverse unlock direction to take an unlocked position against the spring force of the piston spring with the locking device, wherein on the piston rod, an actuating element is arranged axially displaceable, by means of a piston rod spring against the Piston rod is biased in the reverse direction to a stop provided on the piston rod and which is movable with a movement of the piston in the unlocked position on the stop in the unlocking, engages erfindu ngsgemäß the piston spring on the piston via a pressure piece, which is displaceable by means of the piston rod against the spring force of the piston spring relative to the piston in the unlocking direction.

In other words, between the piston and the piston rod according to the invention, a tensile, but not a pressure-resistant connection. Thus, starting from the locking position of the piston, the actuating element with dissolved locking device and pressurizing the pressure chamber in the housing can be pulled by the piston against the force of the piston spring over the stop on the piston rod in the unlocking. In the reverse direction, however, presses, starting from the unlocked position of the piston, the piston spring on the pressure piece directly on the piston rod, which in turn presses when released from the locking piston on the piston rod spring on the actuator. The released from the locking piston can therefore apply in the unlocking tensile forces on the piston rod. In the reverse direction, however, the piston released by the locking device can not transmit compressive forces to the piston rod, so it is pressure-decoupled from the piston rod. Pressure forces are transmitted from the piston spring via the pressure piece rather without piston mediation on the piston rod.

As a result, abuse forces acting on the piston rod in the unlocking direction, such as may be introduced into the piston rod as the actuator recoils, causing the piston rod spring to set (see the above discussion of the prior art), can not penetrate the piston Rather, it is forwarded to the piston spring via the pressure piece lifting off the piston, where it is "sprung" away. Thus, the piston spring is not only used to hold the parking lock module actuation pressure-free blocking position, but decoupled together with the pressure piece at the same time the piston rod of the piston at a non-initiated by the piston movement of the piston rod in the unlocking. As a result, such shocks in the unlocking direction on the piston and the locking means cooperating with the piston can cause no damage.

Preferably, the pressure piece on a side remote from the piston rod side a guide extension, which is guided by means of a guide bush, which in turn is attached to the housing. This advantageously results in a long guide length for the pressure piece, a tilting of the pressure piece with respect to the housing and a possibly associated mechanical stiffness in the pressure piece displacement are avoided. In a preferred embodiment, the guide bush is attached to the housing by means of a bayonet connection. Such a positive connection is - compared to a conceivable screw, welding or adhesive connection between the guide bushing and housing - very easy to assemble. Also, this bayonet connection - in comparison to a principle also possible snap connection between the guide bushing and housing - the advantage that no additional axial mounting path is provided to bring the fasteners together, which in turn is conducive to a short overall length.

For ventilation of the interior of the housing with a displacement of the piston in the interior, a side wall of the housing may be provided with one or more vent holes. In contrast, it is preferred, however, if the guide bush, starting from an end facing away from the piston, is provided with openings for ventilation of the interior of the housing, which is not simply simple - e.g. injection molding technology with the guide bush as a "tool-falling" plastic part, without the need for post-processing - but also minimizes the risk that the openings are covered unintentionally.

In particular assembly suitable design, the piston spring can also be supported with an end remote from the piston on the guide bush, so that the guide bush advantageously also serves as a spring plate and thus combines several functions in itself. Preferably, in this case, the piston spring is designed as a helical compression spring. However, other spring shapes are also conceivable, such as an Evolutfeder or the use of a package of disc springs.

With regard to a particularly smooth, low-backlash and low-wear articulation of the piston rod on the piston, it is further preferred if the piston rod has at its piston-side end a ball head, via which the piston rod is articulated in a bearing cup, which is formed on the piston. Alternatively, however, the piston rod could also have a lenticular head, e.g. interacts with a flat contact surface on the piston to train, which, however, would require a greater clearance and a higher Hertzian pressure between the components involved.

Furthermore, in a preferred embodiment, the pressure piece on a piston rod side facing a bearing projection having a spherical cap bearing surface for the ball head of the piston rod. Again, it is basically conceivable to provide for the piston rod head a straight or flat contact surface on the pressure piece, which in turn is less preferred in view of the larger game and the higher Hertzian pressure in the contact area.

For the formation of the housing, the piston and / or the pressure piece are in principle metallic materials, especially ferrous materials and non-ferrous metals, such as alloys based on aluminum used. With regard in particular to a low weight and a simple, cost-effective production as a mass part, it is preferred, however, if the housing and / or the piston and / or the pressure piece are designed as plastic parts, in particular plastic injection-molded parts.

Here, in a particularly preferred embodiment in the housing, a metallic support plate may be integrated by plastic injection molding, which forms an abutment for the actuating element. In addition to the advantages of a relatively small housing weight and a (still) low wear on the mechanically stressed areas, the support plate can thus accurately and without installation effort be reproducibly positioned exactly with respect to the housing and the parts to be accommodated therein.

For comparable reasons, it is further particularly preferred if the piston designed as a plastic injection-molded part is reinforced for an attack of the locking device with a metallic collar sleeve embedded in the plastic material of the piston.

Regarding the sealing of the pressure chamber in the housing, depending on the place of use of the parking lock module (eg in the gear housing of a motor vehicle) between piston and housing, for example a gap seal, with low, controlled leakage of the pressure medium over the gap, or biased with O-rings, slotted slide rings may be provided. It is preferred, however, if the pressure space between the piston and the housing is sealed by means of a seal assembly to the environment, which comprises two axially spaced, on the piston - or alternatively on the housing - mounted U-rings. Such groove rings with a dynamic sealing lip on the respective running surface and a static sealing lip on the respective mounting surface are readily available as standard parts. The tightness of such a seal arrangement also advantageously allows the use of a separate operating medium for the parking brake module, which may possibly be different from a working medium of the transmission; Also impurities can not enter the pressure chamber from the outside.

In a preferred embodiment of the parking lock module, a sensor arrangement for detecting the position of the piston may further be provided, which has a stationary relative to the housing position detector and a position sensor which is operatively connected to the piston. The detected position of the piston may e.g. be inferred to the respective operating state of the parking brake module (parking lock inserted or parking lock designed). Also, depending on the piston stroke in the housing, the pressurization of the pressure chamber can be controlled.

In principle, it is possible to connect the position sensor of the sensor arrangement directly to the piston or to arrange it on the piston. It is preferred, however, if mounted on the guide extension of the pressure piece, a holder for the position sensor, which allows accurate position detection (also) of the piston rod, which acts on train on the piston and pressure on the pressure piece, but always with the pressure piece in contact stands. In this case, the guide extension of the pressure piece can be performed indirectly via the holder for the position sensor in the guide bush, resulting in a long advantageous leadership length and a low tendency to tilt also for the holder of the position sensor.

Furthermore, in a preferred embodiment, the arrangement may be such that the holder for the position sensor on the guide extension of the pressure piece is axially free of play but held without rotational coupling with the pressure piece. Thus, e.g. As a result of a compression of the piston spring acting torques are not transmitted to the holder and hinder or complicate the axial displacement.

In this case, the holder may be held for the position sensor, for example by means of a locking ring or a screw on the free, remote from the piston end of the guide extension of the pressure piece. In contrast, in particular with regard to a simple assembly and extensive axial backlash preferred, however, is an embodiment in which the holder for the position sensor is held by means of a snap connection on the guide extension of the pressure piece. A snap connection is plastic (injection molding) also good and inexpensive to implement.

Finally, it is preferred if the holder for the position sensor has an arm on which the position sensor is held on the outer circumference of the housing, wherein ribs are formed on the outer circumference of the housing, which guide the holder in the reverse direction or the unlocking direction rail-like and against Secure twisting with respect to the housing. Compared to a likewise conceivable arrangement of the position sensor in the interior of the housing, this embodiment provides in particular a higher flexibility, which on the one hand - as small as possible - dimensions of the position sensor and on the other the placement of the position detector with respect to the position sensor. The above-mentioned management measures with ribs on the housing are also conducive to a high detection accuracy of the sensor arrangement and, moreover, likewise to be realized in a simple and cost-effective manner in terms of plastics technology.

list of figures

• 1 eine perspektivische Ansicht eines erfindungsgemäßen Parksperrenmoduls in seiner Gebrauchslage an einer hier nur schematisch gezeigten Parksperre von schräg oben / vorne links, die über ein auf einer axial verfahrbaren Kolbenstange des Parksperrenmoduls angeordnetes Betätigungselement betätigbar ist, mit Blick auf eine metallische Stützplatte für das Betätigungselement, welche in einem aus Kunststoff bestehenden Gehäuse des Parksperrenmoduls integriert ist;
• 2 eine perspektivische Ansicht des Parksperrenmoduls gemäß 1 von schräg unten / hinten links, mit Blick auf einen Positionsgeber einer Sensoranordnung, der mit einem Kolben des Parksperrenmoduls über einen Halter verbunden ist, welcher außen am Gehäuse mittels eines Führungsabschnitts gegen ein Verdrehen bezüglich des Gehäuses schienenartig geführt ist;
• 3 eine Draufsicht auf das Parksperrenmodul gemäß 1 von oben in 1, mit einer abgebrochen dargestellten Sperrklinke der Parksperre;
• 4 eine Unteransicht des Parksperrenmoduls gemäß 1 von unten in 1;
• 5 eine Rückansicht des Parksperrenmoduls gemäß 1, die in einem Bereich um einen an der Stützplatte befestigten Zentrierstift teilaufgebrochen ist;
• 6 eine um 90° gegen den Uhrzeigersinn in der Zeichnungsebene gedrehte Schnittansicht des Parksperrenmoduls gemäß 1 entsprechend der Schnittverlaufslinie VI-VI in 3, zur Veranschaulichung weiterer Details einer Arretiereinrichtung des Parksperrenmoduls;
• 7 eine um 90° gegen den Uhrzeigersinn in der Zeichnungsebene gedrehte Schnittansicht des Parksperrenmoduls gemäß 1 entsprechend der versetzten Schnittverlaufslinie VII-VII in 3, ebenfalls mit abgebrochen dargestellter Sperrklinke, die neben weiteren Einzelheiten der Stützplatte insbesondere zeigt, wie das Betätigungselement auf der Kolbenstange mit einem über das Kunststoffmaterial des Gehäuses überstehenden Stützabschnitt der Stützplatte in Kontakt steht;
• 8 eine um 90° gegen den Uhrzeigersinn in der Zeichnungsebene gedrehte Schnittansicht des Parksperrenmoduls gemäß 1 entsprechend der versetzten Schnittverlaufslinie VIII-VIII in 4, die u.a. durch hydraulische Anschlüsse des Parksperrenmoduls verläuft;
• 9 eine im Bereich des Gehäuses entsprechend der Schnittverlaufslinie IX-IX in 4 aufgebrochene Seitenansicht des Parksperrenmoduls gemäß 1, wobei sich der Kolben des Parksperrenmoduls in einer mittels der Arretiereinrichtung gegenüber dem Gehäuse arretierten Sperrstellung befindet und dem Positionsgeber gegenüberliegend ein getriebegehäusefester Positionsdetektor schematisch angedeutet ist;
• 10 eine abgebrochene Schnittansicht des Parksperrenmoduls gemäß 1 entsprechend der Schnittverlaufslinie X-X in 4, mit weiteren Details zur schienenartigen Führung des Halters für den Positionsgeber am Gehäuse;
• 11 eine um 90° gegen den Uhrzeigersinn in der Zeichnungsebene gedrehte, abgebrochene Schnittansicht des Parksperrenmoduls gemäß 1 entsprechend der Schnittverlaufslinie XI-XI in 10 im Bereich der schienenartigen Führung des Halters für den Positionsgeber am Gehäuse; und
• 12 eine im Maßstab gegenüber der 1 vergrößerte, perspektivische Ansicht des Parksperrenmoduls gemäß 1 entsprechend dem Detailkreis XII in 2, ohne den Halter für den Positionsgeber, zur Freigabe des Blicks auf den Führungsabschnitt des Gehäuses.

In the following the invention with reference to a preferred embodiment with reference to the accompanying, partially schematic drawings is explained in more detail. In the drawings show:

• 1 a perspective view of a parking lock module according to the invention in its position of use on a parking lock shown here only diagrammatically from obliquely up / left front, which is actuated via an arranged on an axially movable piston rod of the parking brake module actuator with a view to a metallic support plate for the actuator, which is integrated in a plastic housing of the parking lock module;
• 2 a perspective view of the parking lock module according to 1 from obliquely down / back left, overlooking a position sensor of a sensor assembly which is connected to a piston of the parking lock module via a holder which is externally guided on the housing by means of a guide portion against rotation with respect to the housing like a rail;
• 3 a plan view of the parking brake module according to 1 from the top in 1 , with a pawl of the parking brake shown broken off;
• 4 a bottom view of the parking lock module according to 1 from the bottom in 1 ;
• 5 a rear view of the parking lock module according to 1 which is partially broken in an area around a centering pin fixed to the support plate;
• 6 a 90 ° counterclockwise rotated in the drawing plane sectional view of the parking lock module according to 1 according to the cutting line VI-VI in 3 to illustrate further details of a locking device of the parking lock module;
• 7 a 90 ° counterclockwise rotated in the drawing plane sectional view of the parking lock module according to 1 according to the offset cutting line VII-VII in 3 , also shown with broken pawl, which shows, among other details of the support plate in particular, as the actuator is on the piston rod with a projecting beyond the plastic material of the housing support portion of the support plate in contact;
• 8th a 90 ° counterclockwise rotated in the drawing plane sectional view of the parking lock module according to 1 according to the offset cutting line VIII-VIII in 4 , which runs among other things by hydraulic connections of the parking lock module;
• 9 one in the area of the housing according to the cutting line IX-IX in 4 broken side view of the parking lock module according to 1 , wherein the piston of the parking lock module is in a locking position locked by means of the locking device relative to the housing and the position sensor opposite a gearbox fixed position detector is indicated schematically;
• 10 a broken sectional view of the parking lock module according to 1 according to the cutting line XX in 4 , with further details for the rail-like guidance of the holder for the position sensor on the housing;
• 11 a 90 ° counterclockwise rotated in the plane of the drawing, broken sectional view of the parking lock module according to 1 according to the cutting line XI-XI in 10 in the area of the rail-like guidance of the holder for the position sensor on the housing; and
• 12 one in scale over the 1 enlarged, perspective view of the parking lock module according to 1 according to the detail circle XII in 2 , without the holder for the position sensor, to release the view of the guide portion of the housing.

In the drawings, elastic or elastomeric components, namely the dynamic seals are shown to simplify the representation in the undeformed state; in reality, these deformable components abut the adjacent surfaces of adjacent components.

DETAILED DESCRIPTION OF THE EMBODIMENT

In the 1 to 9 numbered the reference number 10 generally a parking brake module for actuating a parking brake 12 in a motor vehicle. The parking lock 12 according to 1 in a conventional manner a Parksperrenrad 14 on, which is arranged rotationally and axially fixed on a gear shaft, not shown, of a motor vehicle transmission and the outer peripheral side a toothing 16 has. For the positive locking of the drive train of the motor vehicle includes the parking brake 12 also a pawl 18 (only in the 1 . 3 and 7 drawn), which on a transmission housing, not shown here about a pivot axis 20 is pivotally hinged. The pawl 18 has a locking tooth 22 that when pivoting the pawl 18 around the pivot axis 20 with the teeth 16 the parking lock wheel 14 can intervene positively. At the reference 24 is a hole in the pawl 18 indicated, on which a not shown here, against the transmission housing supported return spring engages which the pawl 18 around the pivot axis 20 from the parking lock wheel 14 away in an unlocked position.

For pivoting the pawl 18 around the pivot axis 20 is at the parking lock module 10 an actuator 26 provided, which in the illustrated embodiment has a (double) conical surface section 28 having. The actuator 26 is in a manner to be described in more detail by means of a housing 30 of the parking lock module 10 recorded operating mechanism 32 (please refer 9 ) via a hinged to the actuating mechanism 32 connected actuator 34 optionally in a reverse direction S or an unlocking direction e axially displaceable, as in the 1 . 3 . 4 and 9 indicated by arrows. In this case, the conical surface section is supported 28 at one of the actuating mechanism 32 remote end of the actuator 34 worn actuator 26 according to 1 on a housing-fixed cone guide element in the form of a metallic support plate 36 from.

Thus, in an axial movement of the actuating element 26 in the reverse direction S the pawl 18 in 1 against the force of the return spring, not shown, about the pivot axis 20 turned up to the locking tooth 22 with the teeth 16 the parking lock wheel 14 engage positively. In an axial movement of the actuating element 26 in the unlocking direction e however, the conical surface section becomes 28 of the actuating element 26 from its position between pawl 18 and support plate 36 pulled away.

As a result, the pawl 18 in 1 due to the force of the return spring about the pivot axis 20 is lowered in rotation, wherein the locking tooth 22 from the gearing 16 the parking lock wheel 14 disengaged. In other words, the conical surface section 28 of the actuating element 26 such with the support plate 36 be contacted that the conical surface section 28 at one by means of the actuating mechanism 32 generated movement of the actuator 34 in a longitudinal direction on a support portion 38 the support plate 36 supported while under the deflection of the actuator 34 a movement of the actuating element 26 in a transverse direction causes the parking brake 12 to press.

For further details of the actuating mechanism 32 be first of all, in particular 9 Referenced. Accordingly, the actuating mechanism 32 one in the housing 30 of the parking lock module 10 along a central axis M longitudinally slidably received piston 40 that with a piston rod 42 of the actuator 34 is actively connected. The piston 40 is in the reverse direction S via a piston spring 44 with a spring force in a blocking position (in 9 shown) in which it by means of a locking device explained in more detail below 46 optionally opposite the housing 30 can be determined. Furthermore, the piston 40 over one in the housing 30 provided pressure chamber 48 in the direction to the reverse direction S opposite unlocking direction e be pressurized to release the locking device 46 against the spring force of the piston spring 44 to take an unlocked position. Accordingly, the piston 40 depending on the operating state of the locking device 46 be moved from the locked position to the unlocked position and vice versa.

That on the piston rod 42 axially displaceable arranged actuator 26 is further by means of a piston rod spring 50 (Nachrückfeder) opposite the piston rod 42 in the reverse direction S on one on the piston rod 42 provided stop 52 biased. The trained as a helical compression spring piston rod spring 50 serves as an energy store in the event that the pawl 18 when actuated by the parking brake module 10 with her locking tooth 22 against a tooth of the parking lock gear 14 comes to rest, without the teeth 16 to get in shape. In such a situation, the piston rod spring provides 50 for that the spring-biased actuator 26 in a rolling of the motor vehicle, the pawl 18 moves, so that its locking tooth 22 with the teeth 16 the parking lock wheel 14 engaged. In the reverse direction, the actuator 26 with a movement of the piston 40 in the unlocked position over the stop 52 in the unlocking direction e moved, ie pulled.

The respective position of the piston 40 in the case 30 is here by means of a sensor arrangement 54 detectable, the one opposite the housing 30 fixed position detector 56 (in 9 only indicated schematically) and a position sensor 58 that is with the piston 40 is actively connected. More precisely, the outside of the case 30 seated position sensor 58 with the piston 40 over a holder 60 in a manner to be described so coupled that the position sensor 58 a longitudinal movement of the piston 40 over the position detector 56 comprehensible to follow.

As will be explained in more detail below, exist in comparison to the above-described prior art, various peculiarities of the parking brake module 10 according to the illustrated embodiment, especially in the following three points (i to iii): First, (i) engages the piston spring 44 on the piston 40 via a pressure piece 62 on, which by means of the piston rod 42 against the spring force of the piston spring 44 relative to the piston 40 in the unlocking direction e is relocatable (see in particular 9 ). Further, (ii) is the holder 60 for the position transmitter 58 from the piston 40 rotatably coupled and outside the housing 30 of the parking lock module 10 by means of a guide section 64 against twisting about the central axis M guided like a rail (see in particular the 2 and 12 ). In addition, (iii) is the case 30 - next to other parts of the parking lock module 10 - Made of a plastic material and the metallic support plate 36 so in the case 30 integrated that the support section 38 the support plate 36 for contact with the actuator 26 over the plastic material of the housing 30 protrudes (see in particular the 1 and 7 ).

How the particular 7 and 9 show that is an abutment for the actuator 26 training support plate 36 by molding with the plastic of the housing 30 in the case 30 integrated. The transverse to the central axis M extending support plate 36 is in accordance with the 1 and 2 in the area of a front longitudinal end of the parking lock module 10 thus positively in the plastic of the housing 30 held and forms with the housing 30 a part. Here, the support plate is used 36 also for fixing the parking lock module 10 in the motor vehicle and for positioning the parking lock module 10 relative to the parking brake 12 ,

As for the attachment of the parking lock module 10 in the motor vehicle, the support plate 36 according to the 1 to 4 and 7 with mounting holes 66 . 68 Mistake. The mounting holes 66 . 68 in the support plate 36 are as parallel through holes near the respective transverse end of the support plate 36 trained as best in 7 can be seen. In addition, the case is 30 of the parking lock module 10 for fixing the parking lock module 10 in the motor vehicle at one of the support plate 36 spaced location, near a rear longitudinal end of the parking lock module 10 with a mounting hole 70 in a flanschauge 72 of the housing 30 Mistake. Here is the mounting hole 70 with a support sleeve 74 lined in the form of a metallic collar sleeve, by molding with the plastic of the housing 30 in the case 30 is attached, like the 8th shows. In the assembled state of the parking lock module 10 engage in the figures, not shown cap screws the mounting holes 66 . 68 . 70 from the bottom in 1 with radial clearance and are screwed into associated threaded holes of the transmission housing (not shown) to the parking brake module 10 firmly against the gearbox to pull and attach to it.

For axial and angular positioning of the parking lock module 10 regarding the parking lock 12 are also two fixed to the housing 30 connected centering pins 76 . 78 intended. The one centering pin 76 is in one in the support plate 36 next to the mounting hole 66 and bore formed parallel thereto 80 set, for example, pressed as a metallic, cylindrical dowel pin, as in the 5 and 7 shown. The other centering pin 78 however, is near the mounting hole 70 at the flanschauge 72 integral with the housing 30 made of plastic (see 1 and 3 ). The centering pins 76 . 78 stand in 1 up from the flanschauge 72 of the housing 30 or the support plate 36 for engagement with associated positioning holes in the transmission housing (not shown).

Further details of the support plate 36 are in particular the 1 . 7 and 9 refer to. Accordingly, that of the plastic material of the housing 30 released support section 38 the support plate 36 a substantially part-cylindrical surface portion 82 on, against the conical surface section 28 of the actuating element 26 can be brought to the plant. More specifically, the part-cylindrical surface portion 82 on the operating mechanism 32 facing side of the support plate 36 according to 9 with a rounding 84 provided, wherein the conical surface portion 28 of the actuating element 26 at a transition between the rounding 84 and the part-cylindrical surface portion 82 the support plate 36 essentially linearly contacted over a certain arc length, as in 7 shown. For this purpose, a radius of the part-cylindrical surface section 82 of the support section 38 the support plate 36 chosen slightly larger than a largest radius of the conical surface section 28 of the actuating element 26 , In this contact, the actuator 26 according to 7 over a similarly shaped area on the pawl 18 pressed, in turn, by means of the aforementioned, at the bore 24 acting return spring in the direction of the support plate 36 is biased.

According to 9 is the case 30 inside along the central axis M with a continuous, stepped receiving recess 86 provided an interior 88 for receiving the actuating mechanism 32 and in particular the piston 40 limited. The recording opening 86 has two hollow cylindrical recess sections 90 . 92 different diameter, with a step 94 in between, a stop for the piston 40 forms in its locked position. According to the recording opening 86 in the case 30 is the piston 40 stepped formed, with a smaller outer diameter ago, front piston section 96 , a larger from the outer diameter ago, rear piston portion 98 and an annular shoulder 100 in between, with the step 94 of the housing 30 interacts.

As the 9 further shows, is the pressure chamber 48 between the piston 40 and the housing 30 sealed by a seal assembly to the environment, the two axially spaced from each other, on the piston 40 attached grooved rings 102 . 104 includes. More precisely, that is rear, larger diameter piston section 98 with a radial groove 106 for receiving the Nutrings 102 provided while the front, smaller diameter piston section 96 a radial groove 108 for receiving the Nutrings 104 having. It will be apparent to those skilled in the art that the piston 40 Thus seen in an axial projection has an annular hydraulic active surface, which radially outward by a dynamic sealing lip of the Nutrings 102 is limited, which on the inner circumference of the recess portion 92 of the housing 30 is applied, and the radially inward by a dynamic sealing lip of the Nutrings 104 is limited, which on the inner circumference of the recess portion 90 of the housing 30 is applied. About this effective area of the piston 40 in the unlocking direction e hydraulically acted upon. For venting the pressure chamber 48 can be at the bottom of one (or both) radial groove (s) 106 . 108 Venting grooves (not shown) may be provided extending along the central axis M under the respective U-ring 102 . 104 extend.

For the hydraulic loading of the pressure chamber 48 and thus the piston 40 owns the housing 30 according to the 2 . 4 and 8th on the bottom a one-piece molded pressure port 110 that with the pressure room 48 between housing 30 and pistons 40 over a parallel to the central axis M running, in the housing 30 trained connection channel 112 communicates (see the 6 to 8th ). The connection channel 112 flows with an inner end at the stage 94 of the housing 30 , the ring shoulder 100 of the piston 40 opposite, in the pressure room 48 , At its other, outer end is the connecting channel 112 according to the 1 and 7 with a plastic stopper 114 closed to the environment, with the housing 30 is ultrasonically welded.

At the in 9 right end of the front piston section 96 is also designed as a plastic injection-molded part pistons 40 outside circumference for an attack of the locking device 46 with one in the plastic material of the piston 40 embedded, metallic collar sleeve 116 strengthened. The collar sleeve 116 has an outer contour, by means of the locking device 46 a catch of the piston 40 with respect to the housing 30 either in the locked position or in the unlocked position of the piston 40 allowed. For this purpose, the locking device 46 a metallic locking lever 118 on, which is movable in a direction transverse to the central axis M extending detent lever recess 120 of the housing 30 is included. More precisely, the locking lever 118 around a metallic detent lever pin 122 swiveling (see the double arrow in 6 ), which is parallel to the central axis M extends and on both sides of the detent lever recess 120 in the plastic material of the housing 30 is warm-bedded.

How best in 6 can be seen, is the locking lever 118 by means of a detent lever spring 124 counterclockwise in 6 around the detent lever pin 122 in a detent position on the collar sleeve 116 of the piston 40 biased. The trained as a helical compression spring detent lever spring 124 is on one piece with the housing 30 shaped, cylindrical receiving projection 126 guided and accesses an actuating projection 128 of the detent lever 118 at. To the locking lever 118 against the spring force of the detent lever spring 124 optionally from its detent position in one of the collar sleeve 116 on the piston 40 to move distant Entraststellung, which is a movement of the piston 40 along the central axis M allowed, has the locking device 46 two independently controllable Entriegelungsmechanismen on, namely an electrically controllable unlocking mechanism and a hydraulically controlled unlocking mechanism.

The over in the 2 . 4 to 6 and 9 shown connection lugs 130 electrically controllable unlocking the locking device 46 has an electromagnetic actuator 132 (Lifting magnet) on the bottom of the housing 30 of the parking lock module 10 flanged and with screws 134 is held in position. This is the case 30 according to the 2 and 4 with threaded bushes 136 for receiving the screws 134 provided by molding with the plastic of the housing 30 in the case 30 are embedded. The electromagnetic actuator 132 has one in accordance with the electrical control of the actuator 132 according to the double arrow in the 6 and 9 axially displaceable, pin-shaped actuating end 138 , which is consistent with a 6 curved exit end 140 of the detent lever 118 engaged.

For the expert it is apparent that the locking lever 118 by suitable energization of the electromagnetic actuator 132 about that at the end of the lift 140 of the detent lever 118 attacking end of activity 138 of the actuator 132 raised and against the spring force of the detent lever spring 124 in 6 clockwise around the detent lever pin 122 can be pivoted so that the locking lever 118 from the collar sleeve 116 of the piston 40 is released.

A corresponding pivoting of the locking lever 118 around the detent lever pin 122 is possible by means of the hydraulically controllable unlocking mechanism according to this 6 a metallic cylinder pin 142 with a sliding ring 144 having on the outer circumference, which is displaceable in a cylinder bore 146 of the housing 30 is included. For hydraulic loading of the cylinder bore 146 and thus the cylinder pin 142 owns the housing 30 according to the 4 and 8th on the bottom one on the housing 30 in parallel arrangement to the pressure connection 110 integrally formed further pressure port 148 , The latter communicates via a in the housing 30 trained, obliquely to the central axis M extending, another connecting channel 150 with the cylinder bore 146 (see the 4 and 6 to 8th ). The connection channel 150 cuts the cylinder bore with its inner end 146 , as in 6 shown. At its other, outer end is also the connecting channel 150 according to the 1 and 7 with a plastic stopper 152 sealed to the environment, with the housing 30 is ultrasonically welded.

For the expert, in turn, it can be seen that when hydraulic loading of the cylindrical pin 142 over the pressure connection 148 and the connection channel 150 the cylinder pin 142 in 6 according to the double arrow in the cylinder bore 146 is raised, the cylinder pin 142 with his over the case 30 projecting end to a nose-shaped Aushebevorsprung 154 of the detent lever 118 comes to the plant. This is the locking lever 118 raised and in 6 against the spring force of the detent lever spring 124 clockwise around the detent lever pin 122 pivoted so that the locking lever 118 from the collar sleeve 116 of the piston 40 is released. The - electromagnetically or hydraulically causes - of the locking device 46 released pistons 40 can depending on the operating state of the parking brake 12 now by the spring force of the piston spring 44 from its unblocking position in its blocking position or by hydraulic loading of the pressure chamber 48 be moved from its blocking position to its unlocked position.

As further, in particular the 9 shows is the piston 40 designed as a rotationally symmetrical hollow part, the in 9 from right to left a funnel-shaped opening area 156 , a reception area 158 for the piston end of the piston rod 42 and a hollow cylindrical receiving area 160 for the piston end of the pressure piece 62 having. The piston rod 42 extends into 9 to the right from the opening area 156 of the piston 40 out, with one on the piston rod 42 trained abutment collar 162 for the piston rod spring 50 axially in the opening area 156 of the piston 40 located. In accordance with an outer diameter of the abutment collar 162 can the piston rod 42 with respect to the piston 40 in the opening area 156 pivot.

At its piston-side end, the metallic piston rod 42 a ball head 164 on, in the middle reception area 158 of the piston 40 is held. This is the ball head 164 on a complementary to the ball head 164 shaped, on the piston 40 trained pan 166 on, so that the piston rod 42 on the piston 40 is hinged. The pressure piece 62 has on one of the piston rod 42 facing side a bearing projection 168 that is in the receiving area 158 of the piston 40 extends into it and a spherical cap-shaped contact surface 170 for the ball head 164 the piston rod 42 has. Between the pan 166 of the piston 40 and the spherical cap-shaped contact surface 170 of the pressure piece 62 is the ball head 164 the piston rod 42 kept essentially free of play.

In the in 9 left recording area 160 of the piston 40 is finally a headboard 172 of the pressure piece 62 recorded, which is also designed as a plastic injection molded part. At the headboard 172 of the pressure piece 62 is the bearing projection 168 integrally formed. Furthermore, the head part 172 of the pressure piece 62 with a bunch 174 provided, which is an abutment for the piston-side end of the piston spring 44 trains the headboard 172 surrounds and moves into the reception area 160 of the piston 40 extends into it. The trained as a helical compression spring piston spring 44 clamps the pressure piece 62 with his covenant 174 against an annular shoulder 176 of the piston 40 in front, between the receiving area 158 and the recording area 160 of the piston 40 lies.

In particular the 9 is also apparent that the pressure piece 62 on one of the actuator 34 or the piston rod 42 side facing away from a leadership extension 178 having. The himself at the head part 172 of the pressure piece 62 integrally connected, pin-like leadership extension 178 is, as will be described in more detail by means of a guide bush 180 opposite the housing 30 led, in turn, on the housing 30 is attached. In the illustrated embodiment, which is also designed as a plastic injection molded part guide bushing 180 by means of a in the 2 to 5 and 9 generally with the reference numeral 182 Marked bayonet connection to the housing 30 attached. Such a bayonet connection 182 is for the application of a clutch master cylinder as a hydraulic cylinder in the German patent application DE 10 2016 006 053 A1 The same applicant described in detail, to which reference is made expressly at this point in terms of structure and function of this compound.

According to 9 the piston spring is supported 44 with her from the piston 40 opposite end to the guide bush 180 from. More precisely, the guide bush 180 on her the interior 88 of the housing 30 facing side with a ring recess 184 provided, in which the from the piston 40 opposite end of the piston spring 44 in extends. The guide bush 180 thus also serves as a housing-side spring plate for the piston spring 44 ,

In that regard, it can be seen that any shocks on the piston rod 42 in the unlocking direction e such as when the actuator recoils 26 under setting of the piston rod spring 50 over the abutment collar 162 into the piston rod 42 can be initiated, not on the piston 40 can penetrate, but on the pressure piece 62 through the piston spring 44 cushioned on the guide bush 180 and thus the case 30 be transmitted. In other words, there is between the piston 40 and the piston rod 42 Although a high-tensile form-fitting connection by conditioning the ball head 164 the piston rod 42 at the pan 166 of the piston 40 , but no pressure-resistant connection, because of the ball head 164 the piston rod 42 over the bearing projection 168 pushed pressure piece 62 from the piston 40 at the ring shoulder 176 of the piston 40 can lift off when on the piston rod 42 applied compressive forces the biasing force of the piston spring 44 exceed.

The guide bush 180 Furthermore, also comes a venting function. How the particular 2 and 5 show, is the guide bush 180 starting from one from the piston 40 opposite end with openings 186 for venting the interior 88 of the housing 30 Mistake. In the illustrated embodiment, which are parallel to the central axis M extending openings 186 on a common pitch circle and are around the central axis M evenly spaced apart from each other (see 5 ).

Further details of the sensor arrangement 54 are in particular the 2 . 4 . 5 and 9 to 12 refer to. In the sensor arrangement 54 it is preferably a Hall sensor, with a Hall element (not shown in detail) as part of the housing-fixed position detector 56 ( 9 ) and a magnet as a position sensor 58 that about the holder 60 with the piston 40 connected is. The position transmitter 58 can eg on the holder 60 however, it is preferred as a plastic-bonded magnet in the holder 60 injected, which is also designed here as a plastic injection molded part.

The holder 60 for the position transmitter 58 generally has an angled arm 188 on, on which the position sensor 58 on the outer circumference of the housing 30 is held. Furthermore, the holder has 60 for movement coupling with the piston 40 one concentric with the central axis M arranged connecting portion 190 , with the angled arm 188 is connected, more specifically, in the illustrated embodiment in one piece with the arm 188 from the plastic material of the holder 60 spiked.

For the motion coupling with the piston 40 the connection section extends 190 of the owner 60 according to 9 in the interior 88 of the housing 30 into it. In this case, the sleeve-shaped connecting portion 190 of the owner 60 by means of the housing 30 attached guide bush 180 guided and on the leadership extension 178 of the pressure piece 62 axially essentially free of play but without rotary coupling with the pressure piece 62 held. In other words, the guide extension extends 178 of the pressure piece 62 in the connecting section 190 of the owner 60 into and through it, so that the guiding process 178 of the pressure piece 62 indirectly over the holder 60 , more precisely its connecting section 190 in the guide bush 180 is guided, for this purpose in a central region a hollow cylindrical guide surface 192 having.

In 9 can also be seen that the motion coupling of the holder 60 for the position transmitter 58 with the piston 40 a snap connection 194 is provided. By means of the snap connection 194 is the holder 60 for the position transmitter 58 at the leadership extension 178 of the pressure piece 62 held, with the snap connection 194 at a piston near end of the connecting portion 190 of the owner 60 is provided. The connecting section 190 of the owner 60 is here for the formation of spring arms 196 slotted several times, the inner peripheral side nose-like projections at their free ends 198 have. The nose-like projections 198 engage behind in the assembled state of the holder 60 a ring collar 200 on the guidance process 178 of the pressure piece 62 , Because the connecting section 190 of the owner 60 also on the front side of the headboard 172 of the pressure piece 62 can get to the plant, is the connecting section 190 of the owner 60 on the pressure piece 62 fixed axially positive fit, however, allows a relative rotation of the pressure piece 62 concerning the owner 60 ,

With regard to the aforementioned guide section 64 to the rail-like guidance of the holder 60 for the position transmitter 58 outside on the housing 30 of the parking lock module 10 continue to be particularly to the 2 and 12 directed. Accordingly, the guide section 64 on the outer circumference of the housing 30 in one piece from the plastic material of the housing 30 molded ribs 202 . 204 on that the holder 60 in the reverse direction S or the unlocking direction e run like a rail and against twisting with respect to the housing 30 to back up. Ribs 202 . 204 run along the central axis M and are transverse to the central axis M running ribs 206 stiffened.

Here, the guide section 64 on the outer ribs 202 parallel to the central axis M extending, facing each other first guide surfaces 208 on, with the first, lateral contact surfaces 210 on the arm 188 of the owner 60 for the position transmitter 58 interact (see also 10 ) to the locator 58 against twisting about the central axis M support. Furthermore, the guide section has 64 at least one, in the illustrated embodiment, two on the inner ribs 204 trained, between the central axis M and the locator 58 lying further guide surfaces 212 according to 11 with at least one other contact surface 214 on the arm 188 of the owner 60 for the position transmitter 58 interact with the locator 58 in relation to the central axis M Support radial direction. Due to the plastic training of the holder 60 and the shrinkage behavior of the plastic after the injection molding is the arm 188 of the owner 60 with the further contact surface 214 with light spring force on the other guide surfaces 212 of the guide section 64 of the housing 30 at.

From the preliminary description it is apparent that the holder 60 with his angled arm 188 or the connection section 190 relative to the central axis M both in the circumferential direction - between the ribs 202 - As well as in the radial direction - on the ribs 204 and between the guide surface 192 the guide bush 180 and the guiding process 178 of the pressure piece 62 - Is performed essentially free of play or very low backlash. In addition, also has the axial coupling of the holder 60 to the pressure piece 62 - at the snap connection 194 - very little game on. All this is a high detection accuracy and reliability of the sensor array 54 conducive. Nevertheless, the holder is 60 and thus the position transmitter 58 with respect to the position detector 56 with very little displacement forces along the central axis M displaceable because of the holder 60 from the pressure piece 62 is torsionally coupled, so that torques, such as when compression of the piston spring 44 arise, not from the pressure piece 62 on the holder 60 can be transferred and as a result the holder 60 in his leadership on the case 30 can not tilt.

By means of the sensor arrangement 54 finally, on the one hand, the respective actuation state of the parking lock module 10 be detected, ie whether the piston 40 the actuating mechanism 32 in the locked position according to 9 or in the unlocked position. On the other hand can damage the parking brake module 10 , eg a possible breakage of the piston spring 44 detect. In addition, however, can also be put on or laying out the parking brake 12 be controlled, namely by detecting the stroke of the piston 40 and dependent pressurization of the pressure chamber 48 , It is also possible, the aforementioned "ratcheting" of the pawl 18 above the gearing 16 the parking lock wheel 14 determine what, by pressurizing the pressure chamber 48 can be counteracted.

A parking brake module has a housing in which a piston operatively connected to a piston rod is received, which is biased in a locking direction via a piston spring into a blocking position in which it can be fixed by means of a locking device relative to the housing. Furthermore, the piston can be pressurized via a pressure chamber in an unlocking direction opposite to the blocking direction in order to assume an unlocking position when the locking device is released, counter to the piston spring force. On the piston rod an actuating element is slidably disposed, which is biased by a piston rod spring relative to the piston rod in the reverse direction to a stop on the piston rod and which is movable with a piston movement in the unlocked position on the stop in the unlocking direction. For pressure decoupling of piston rod and piston, the piston spring engages the piston via a pressure piece, which is displaceable by means of the piston rod against the piston spring force relative to the piston in the unlocking direction.

LIST OF REFERENCE NUMBERS

10

Parking lock module

12

parking lock

14

parking gear

16

gearing

18

pawl

20

swivel axis

22

locking tooth

24

drilling

26

actuator

28

conical surface section

30

casing

32

actuating mechanism

34

actuator

36

metallic support plate

38

support section

40

piston

42

piston rod

44

piston spring

46

locking

48

pressure chamber

50

Piston rod spring

52

attack

54

sensor arrangement

56

position detector

58

locator

60

holder

62

Pressure piece

64

guide section

66

mounting hole

68

mounting hole

70

mounting hole

72

Flanschauge

74

support sleeve

76

Centering

78

Centering

80

drilling

82

part-cylindrical surface section

84

rounding

86

receiving recess

88

inner space

90

recess portion

92

recess portion

94

step

96

front piston section

98

rear piston section

100

annular shoulder

102

Nutring

104

Nutring

106

radial groove

108

radial groove

110

pressure connection

112

connecting channel

114

Plastic plugs

116

collar sleeve

118

locking lever

120

Locking lever recess

122

Locking lever pin

124

Locking lever spring

126

receiving projection

128

operating projection

130

terminal lug

132

electromagnetic actuator

134

screw

136

threaded bushing

138

actuating end

140

Aushebeende

142

straight pin

144

sliding ring

146

bore

148

pressure connection

150

connecting channel

152

Plastic plugs

154

Aushebevorsprung

156

opening area

158

reception area

160

reception area

162

Abutment collar

164

ball head

166

bearing cup

168

bearing projection

170

spherical cap-shaped contact surface

172

headboard

174

Federation

176

annular shoulder

178

Guide extension

180

guide bush

182

bayonet connection

184

ring recess

186

opening

188

angled arm

190

connecting portion

192

hollow cylindrical guide surface

194

snap

196

spring arm

198

nose-like projection

200

collar

202

rib

204

rib

206

rib

208

guide surface

210

contact surface

212

guide surface

214

contact surface

e

unlocking direction e

M

central axis M

S

reverse direction S

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102015008709 A1 [0004]
• DE 102016006053 A1 [0055]

Claims (15)

A parking brake module (10) for actuating a parking brake (12) in a motor vehicle, having a housing (30) in which a piston (40) operatively connected to a piston rod (42) is received, which is in a locking direction (S) via a piston spring ( 44) is biased by a spring force into a blocking position in which it can be fixed by means of a locking device (46) selectively with respect to the housing (30) and via a pressure chamber (48) in an unlocking direction (E) opposite to the locking direction (S). can be pressurized in order to take an unlocked position against the spring force of the piston spring (44) when the locking device is released, wherein an actuating element (26) is arranged axially displaceably on the piston rod (42), which is displaceable by means of a piston rod spring (50) relative to the piston rod (46). 42) is biased in the reverse direction (S) onto a stop (52) provided on the piston rod (42) and which is in the movement with a movement of the piston (40) Unlocking position on the stop (52) in the unlocking (E) is movable, characterized in that the piston spring (44) on the piston (40) via a pressure piece (62) engages, which by means of the piston rod (42) against the spring force of Piston spring (44) relative to the piston (40) in the unlocking direction (E) is displaceable. Parking lock module (10) after Claim 1 , characterized in that the pressure piece (62) on a side facing away from the piston rod (42) side a guide extension (178) which is guided by means of a guide bush (180), which in turn on the housing (30) is fixed, preferably by means of a Bayonet connection (182). Parking lock module (10) after Claim 2 , characterized in that the guide bush (180), starting from a piston (40) facing away from the end with openings (186) for venting an interior (88) of the housing (30) is provided. Parking lock module (10) after Claim 2 or 3 , characterized in that the piston spring (44) with a piston (40) facing away from the end of the guide bush (180) is supported, wherein the piston spring (44) is preferably designed as a helical compression spring. Parking brake module (10) according to any one of the preceding claims, characterized in that the piston rod (42) at its piston end has a ball head (164) via which the piston rod (42) in a bearing cup (166) is articulated, which on the piston (40) is formed. Parking lock module (10) after Claim 5 , characterized in that the pressure piece (62) on one of the piston rod (42) side facing a bearing projection (168) having a spherical cap-shaped contact surface (170) for the ball head (164) of the piston rod (42). Parking brake module (10) according to any one of the preceding claims, characterized in that the housing (30) and / or the piston (40) and / or the pressure piece (62) are designed as plastic injection molded parts. Parking lock module (10) after Claim 7 , characterized in that in the housing (30) a metallic support plate (36) is integrated by plastic injection molding, which forms an abutment for the actuating element (26). Parking lock module (10) after Claim 7 or 8th , characterized in that the piston formed as a plastic injection-molded part (40) for an attack of the locking device (46) with a in the plastic material of the piston (40) embedded metallic collar sleeve (116) is reinforced. Parking brake module (10) according to one of the preceding claims, characterized in that the pressure chamber (48) between the piston (40) and the housing (30) is sealed by means of a seal assembly to the environment, the two axially spaced, on the piston (40 ) includes grooved rings (102, 104). Parking brake module (10) according to any one of the preceding claims, characterized by a sensor arrangement (54) for detecting the position of the piston (40) having a relative to the housing (30) fixed position detector (56) and a position sensor (58) connected to the piston (40) is operatively connected. Parking lock module (10) after at least the Claims 2 and 11 , characterized in that on the guide extension (178) of the pressure piece (62) a holder (60) for the position sensor (58) is mounted, wherein the guide extension (178) of the pressure piece (62) preferably indirectly via the holder (60) for the position sensor (58) in the guide bush (180) is guided. Parking lock module (10) after Claim 12 , characterized in that the holder (60) for the position sensor (58) on the guide extension (178) of the pressure piece (62) axially free of play but without rotational coupling with the pressure piece (62) is held. Parking lock module (10) after Claim 12 or 13 , characterized in that the holder (60) for the position sensor (58) by means of a Snap connection (194) on the guide extension (178) of the pressure piece (62) is held. Parking lock module (10) according to one of Claims 12 to 14 , characterized in that the holder (60) for the position transmitter (58) has an arm (188) on which the position sensor (58) is held on the outer circumference of the housing (30), wherein on the outer circumference of the housing (30) ribs (18) 202, 204) are formed, which guide the holder (60) in the locking direction (S) and the unlocking direction (E) like a rail and secure against rotation relative to the housing (30).

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