Locking unit with centre piece

The disclosure relates to a locking unit, in particular for the parking lock of an automatic transmission, for locking the movement of a piston which is movable by a drive and in particular can be acted upon with pressure or hydraulic pressure, wherein the piston is at least partially mounted in a center section which is at least partially surrounded by a housing.

INTRODUCTION

The disclosure relates to a locking unit, in particular for the parking lock of an automatic transmission, for locking the movement of a piston which is movable by a drive and in particular can be acted upon with pressure or hydraulic pressure, the locking unit having a solenoid and at least one latching element, and the latching element interacting with the armature or the armature rod of the solenoid, and the piston having at least one latching receptacle, and the piston being securable by the retaining interaction of the latching element with the latching receptacle.

SUMMARY

It is an object of the disclosure, per an embodiment, to design a known locking unit in an alternative or better manner.

The disclosure, per an embodiment, relates to a locking unit, in particular for the parking lock of an automatic transmission, for locking the movement of a piston which is movable by a drive and in particular can be acted upon with pressure or hydraulic pressure, the locking unit having a solenoid and at least one latching element, and the latching element interacting with the armature or the armature rod of the solenoid, and the piston having at least one latching receptacle, and the piston being securable by the retaining interaction of the latching element with the latching receptacle.

According to an embodiment of the disclosure, it is provided that the piston is at least partially mounted in a center section which is at least partially surrounded by a housing, and the locking unit has a latching unit, which supports the latching elements, wherein the latching unit and the center section (6) are formed integrally. It has been shown that this leads to an advantageous operation, according to an embodiment, and permits a high degree of stability and is simple to manufacture.

The center section can in particular be designed in the manner of a sleeve.

An inner side of the center section, per an embodiment, preferably forms a bearing surface for the piston or for a piston thrust piece of the piston. The piston can thereby be advantageously mounted.

The center section can be in the form in particular of a turned part or sintered shaped part, can be produced in a formative method or can be produced by means of 3D printing, metal powder injection molding, selective laser melting or selective laser sintering. Such methods have proven advantageous. However, other methods are also possible.

The center section, per an embodiment, preferably has an axial length of 100% to 200% or of 130% to 170% of a stroke of the piston.

The center section furthermore, per an embodiment, preferably has an axial length of 30% to 40% of an axial length of the piston.

The center section furthermore, per an embodiment, preferably has an axial length of 13% to 20% of an axial length of the locking unit.

According to an embodiment, it is provided that the piston is hollow on the inside completely along its axial extent. Weight can thereby be saved.

In particular, it can be provided that the piston has a cavity which extends axially though the entire piston.

The cavity is, per an embodiment, preferably open at both axial ends.

It is provided, per an embodiment, that the cavity has a wall continuously or in sections which is thinner than a quarter of a diameter of the piston or is thinner than a tenth of the diameter of the piston.

According to an embodiment, it is provided that the piston has a completely hollow piston tube along one axial portion and a piston thrust piece, which is connected to the piston tube, along a further axial portion. As a result, piston tube and piston thrust piece can be optimized separately from each other in accordance with their respective functions.

The latching receptacles are, per an embodiment, preferably formed in the piston thrust piece. The piston thrust piece is preferably closer to the solenoid and more solid than the piston tube.

The piston tube can be in the form in particular of a deep drawn part, from tool steel or from metal. However, other embodiments are also possible.

According to an embodiment, it is provided that the piston tube has a wall thickness of 5% to 15% of the diameter of the piston tube.

It is preferably, per an embodiment, provided that the piston is at least partially mounted or arranged in the housing.

According to an embodiment, it is provided that the housing is at least partially, preferably completely, formed from plastic. This has proven advantageous, in particular because of the easy processability and the low weight. However, other materials are also possible.

The piston tube, per an embodiment, preferably has a tube center section with an outer tapering, wherein the tapering of the piston tube interacts with a step formed in the housing, in order to limit a movement of the piston away from the solenoid. Said movement can thereby be limited simply and reliably.

In particular, per an embodiment, a piston spring can be provided between housing and piston, said piston spring pushing the piston in the direction of the solenoid. The piston can thereby be pretensioned into an inoperative position which it takes up in particular in the absence of an active actuation, i.e., for example, in the absence of a pressurized fluid and if blocking is absent.

According to an embodiment, it is provided that the piston is mounted opposite the solenoid in a plain bearing of the housing. This permits reliable guidance of the piston.

The housing or the locking unit can have an inner tube section.

The inner tube section can be considered in general to be part of the locking unit or part of the housing.

In particular, per an embodiment, a pressure conducting channel can be formed on the outer side of the tube section. A pressurized medium can flow into said pressure conducting channel in order to actuate the piston. For example, by means of a tightness, described further below, between tube section and housing, the medium can be conducted to a position at which it is required for driving the piston.

The pressure conducting channel is preferably, per an embodiment, hydraulically connectable from the outside via a connection through the housing. This makes it possible to supply pressurized fluid.

The center section preferably, per an embodiment, has a radial outer side which supports the housing. This permits a reliable connection between housing and center section.

The center section can be connected to a solenoid housing of the solenoid. This permits a secure reference between the two components.

The center section can have an encircling contact shoulder on its side facing away from the solenoid and/or facing the piston tube, which contact shoulder is adjoined by an annular and/or conical connecting region.

According to an embodiment, it is provided that the connecting region supports the tube section. The tube section can thereby be reliably fastened.

A number of segment interspaces as notches can be formed in the connecting region, in particular, per an embodiment, radially on the outer side. As a result, for example, a passage of fluid can be made possible.

The segment interspaces are preferably, per an embodiment, designed as a fluidic connection between pressure conducting channel and a pressure space within the tube section. This makes it possible to conduct pressure out of the pressure conducting channel into the pressure space.

Respective supporting segments which support the tube section can be formed between the segment interspaces. This permits a secure connection to the tube section. The connecting region can be designed in particular as a crown ring.

According to an embodiment, it is provided that the locking unit has a latching unit which supports the latching elements.

The latching unit can have a portion facing the solenoid or an armature space of the solenoid and a portion facing the piston, which portions are both of sleeve-shaped design.

It is preferably provided, per an embodiment, that that portion of the latching unit which faces the solenoid partially accommodates the armature in at least one end position.

An interior space which is open on the piston side is preferably, per an embodiment, formed in the latching unit or in that portion of the latching unit which faces the piston.

An exterior space can be formed between latching unit and housing or between latching unit and center section.

Exterior space and interior space can be fluidically connected via an equalizing opening formed in the latching unit. This can permit an equalization of the pressure.

It is preferably provided, per an embodiment, that the exterior space is vented by a channel which is formed in or on the center section. The exterior space can thereby be kept at ambient pressure. The interior space can therefore also be kept at ambient pressure by means of the equalizing opening which has already been mentioned.

The latching unit is preferably, per an embodiment, fixedly connected directly or indirectly to the housing. This permits a constant positional relationship.

In particular, per an embodiment, a control element which is fixedly connected to the armature rod can be arranged in the latching unit. Said control element can serve for actuating the latching elements.

The control element is preferably, per an embodiment, at least partially movable within the portion facing the piston.

According to an embodiment, it is provided that a number of radial bores for receiving the latching elements is formed in the latching unit. The latching elements can thereby be reliably guided.

The latching elements can be formed spherically. However, other shapes are also possible.

The control element can be designed in order, at least in one position, to push the latching elements radially outward. They can thereby deploy a blocking effect.

It is preferably provided, per an embodiment, that the latching elements, when they are pushed radially outward, come into engagement with one of the latching receptacles. As a result, they can block a movement of the piston.

The piston preferably, per an embodiment, has at least two latching receptacles spaced apart axially from one another. This permits blocking of the piston in at least two positions. However, the use of more than two latching receptacles is also possible.

The piston is furthermore, per an embodiment, preferably lockable in two different positions by means of the two latching receptacles. Accordingly, if there are more than two latching receptacles, it is also possible for there to be locking in more than two positions.

The solenoid can have a solenoid core which is arranged at an axial end of the locking device.

The armature rod is, per an embodiment, preferably guided in a bore of the solenoid core. This permits reliable guidance of the armature rod.

The piston preferably, per an embodiment, has an axially end-side connecting region which protrudes out of the housing even when the piston is fully retracted. This permits a simple connection of an external element to the piston.

The connecting region can be designed in the manner of a fork. This permits an advantageous fastening of typical external elements. The connecting region can also be designed as a punched-out fork head.

According to an embodiment, it is provided that the piston or the piston thrust piece is at least partially arranged radially between latching unit and housing or is arranged between latching unit and center section.

The solenoid preferably, per an embodiment, has a winding for generating a magnetic field for moving the armature and/or the armature rod. This permits a simple actuation.

The inner tube section, per an embodiment, is preferably designed as a guide of the piston. The guide on the tube section achieves particularly good guidance of the piston, and therefore the latter can be moved in as smooth-running a manner as possible.

The pressure conducting channel is, per an embodiment, preferably limited at least partially radially, with respect to the longitudinal axis of the piston, on the inside by the outer side of the tube section and on the outside by the inner wall of the housing.

The tube section can be connected to the housing or can be part of the housing.

The piston preferably, per an embodiment, lies against the tube section. This permits advantageous guidance of the piston along the tube section. The contact can take place along a full circumference.

It is preferably provided, per an embodiment, that the piston slides along the tube section.

According to an embodiment, the piston lies in a fluid-tight manner against the tube section. The piston can thereby be advantageously actuated by pressure.

The piston preferably, per an embodiment, has a sealing means which seals the piston in a fluid-tight manner on the tube section. This permits a particularly leakproof design.

The sealing means can be, for example, a sealing ring or an O ring. The sealing ring or the O ring can be provided in an encircling step of the piston.

The sealing ring or the O ring is, per an embodiment, preferably provided in a piston thrust piece of the piston.

The inner side of the tube section, per an embodiment, preferably forms a housing inner wall against which the piston lies.

The tube section is, per an embodiment, preferably of rectilinear and/or cylindrical design at least along a portion on which the piston is guided. This permits an advantageous interaction with the piston.

The tube section is, per an embodiment, preferably formed from metal or from plastic. These materials have proven advantageous. However, the use of other materials is also possible.

According to an embodiment, it is provided that the center section is designed in the axial direction, with respect to the longitudinal axis of the piston, to be shorter on the piston side than the latching unit and in particular the radial bores of the latching unit are not concealed in the radial direction, with respect to the longitudinal axis of the piston, by the center section.

According to an embodiment, it is provided that the inner tube section is connected in a fluid-tight manner to the housing.

The effect which can be achieved in an advantageous manner by such a fluid-tight embodiment is that leakage between tube section and housing is prevented. Such leakage could lead, for example, to pressurized fluid escaping into a space in which it could prevent the movement of the piston.

According to an embodiment, it is provided that the tube section is accommodated in a groove of the housing. This makes reliable holding possible.

The groove of the housing can be of annular design. It can therefore be advantageously adapted to a cylindrical tube section.

According to an embodiment, it is provided that a seal is arranged between housing and tube section. A sealing effect can therefore be achieved.

The seal can be arranged in particular in the groove. It can be an O ring or sealing ring. The seal can also be a sealing material or a silicone sealing material. Such embodiments have proven advantageous.

According to an embodiment, it is provided that a number of bores in which engagement parts of the housing engage is formed in the tube section. An advantageous fastening and/or sealing, per an embodiment, can thereby be achieved. The engagement parts can be formed in particular in an internally bonded manner with the rest of the housing. They can be produced, for example, by insert molding of the tube section during production of the housing.

According to an embodiment, it is provided that the housing has an in particular annular projection which partially engages around the tube section. The tube section can therefore be held and also sealed.

The projection can limit the groove in particular radially on the inner side.

According to an embodiment, it is provided that the tube section is connected to the housing in a gas-tight and/or pressure-tight manner. Tightness going beyond the fluid tightness can thereby be achieved.

According to one embodiment, the housing can support the tube section. This permits an exact positional relationship between tube section and housing.

According to one embodiment, latching unit and center section can be produced or formed integrally as an integral injection molded part or in an additive manufacturing method. A number of radial recesses, in particular bores, can therefore also be formed in the latching unit for receiving the latching elements.

Center section and latching unit can be formed in particular integrally. The center section can be designed in the axial direction, with respect to the longitudinal axis of the piston, to be shorter on the piston side than the latching unit. In particular, it can be provided that the radial bores of the latching unit are not concealed in the radial direction, with respect to the longitudinal axis of the piston, by the center section. This permits formation of the bores by tools, such as drills, which can be guided past the center section.

The disclosure furthermore relates to a method for producing a locking unit according to the disclosure, wherein the tube section is provided and the housing is insert molded around the tube section. By means of such a method, the housing can be produced and connected to the tube section in a simple manner. With regard to the locking unit, recourse can be made to all of the embodiments and variants described herein.

According to an alternative method procedure, a groove into which the tube section is introduced subsequently can be formed in the housing.

A number of bores can be formed in the tube section, wherein a number of engagement parts which each engage in a bore have been or are formed in the housing. This permits a reliable connection. The engagement parts can be formed in particular in a materially bonded manner with the rest of the housing.

For example, it can be provided that the piston is hollow on the inside.

The piston according to the aforementioned prior art is a complicated turned part which is produced in a production process comprising a plurality of different machining steps. An aspect of a hollow design is focused on producing the individual components in simple production methods. The proposed piston can be provided as a deep drawn part in which the relatively complex contour of said piston is realized in one processing step. In addition to the significantly more favorable production, the mass of such a piston can be reduced at the same time, which overall reduces the mass of the locking unit proposed according to the disclosure, which firstly saves on resources and secondly also permits the drives which are to be used to be realized in smaller form, with the same dynamic properties, and thus also to be more cost-effective and also lighter.

According to one embodiment, it can also be provided that the piston is at least partially mounted in a housing which is at least partially formed from plastic.

The housing according to the aforementioned prior art is also a complicated, cylindrical metal turned part, the inner side of which is manufactured with high precision.

In an embodiment proposed herein, the housing can be composed, for example, of plastic, wherein the plastic, for example, is sprayed onto the structure, or the housing is kept as a finished injection molded component in which the individual parts of the locking unit according to an embodiment of the disclosure are then installed. The proposal according to an embodiment of the disclosure comprises in this case both a direct mounting of the piston on the plastic, wherein then, for example, the inner side of the plastics housing can have a corresponding wear-reducing sliding configuration, such as, for example, a sliding coating or the like, and also an indirect mounting of the piston in the housing formed from plastic. For example, in the case of the indirect mounting in the plastics housing, a corresponding guide sleeve, preferably composed of metal, or a guide tube can thus be provided, the inner side of which interacts with the outer side of the piston.

The plastics housing which can be realized as an injection molded part or as an insert molded part can be produced more simply and therefore more cost-effectively than the submissions from the prior art. The proposal is also not only limited here to the more favorable manner of production, but in turn reduces the mass of the entire locking unit since a lighter material is used for the housing.

It can also be provided that the piston is, per an embodiment, at least partially mounted in a center section which is at least partially surrounded by a housing.

This variant has the advantage, per an embodiment, that the piston is first of all guided only on the center section. A guide in the housing can be dispensed with here, but it may also be additionally provided. According to this proposal, the housing can be a component which is separate from the center section and can then be optimized in accordance with other aspects since it, for example, no longer primarily has the task of supporting the piston. Since the housing is relatively large, it can then be manufactured from a lighter material (e.g. plastic) than the material of the center section which takes on the supporting tasks and therefore is preferably composed, per an embodiment, for example, of a corresponding metallic bearing material.

In an embodiment of the proposal, it is provided that the piston is divided in two and has a hollow, for example deep drawn, piston tube and a piston thrust piece designed, for example, as a turned part.

In an embodiment of the proposal, it is provided that the piston, in particular the piston tube, is of fork-like design at its outer end.

In an embodiment of the proposal, it is provided that the piston, preferably the piston thrust piece, has two latching receptacles which are offset axially with respect to each other.

In an embodiment of the proposal, it is provided that at least part of the piston, preferably the entire piston, is designed as a deep drawn part.

In an embodiment of the proposal, it is provided that the housing which is manufactured from plastic includes or surrounds a sleeve section or tube section.

In an embodiment of the proposal, it is provided that the outer side of the tube section limits a pressure conducting channel.

In an embodiment of the proposal, it is provided that the sleeve section or tube section is placed or pressed onto a center section.

In an embodiment of the proposal, it is provided that the inner side of the sleeve section or tube section forms a mounting for the piston or the piston tube.

In an embodiment of the proposal, it is provided that a venting channel is provided on the center section, preferably on the side facing the solenoid.

In an embodiment of the proposal, it is provided that the piston spring is located within or outside the center part.

In an embodiment of the proposal, it is provided that the center section is in the form of a sintered shaped part or is manufactured in a formative method, in particular by means of 3D printing, metal powder injection molding, selective laser melting or selective laser sintering. Sintering or formative manufacturing are cost-effective production methods with which, in addition, workpieces of virtually any shape can be produced in a single working cycle.

In an embodiment of the proposal, it is provided that the center part permits a radial orientation of the latching unit.

Furthermore, the disclosure also comprises the use of the locking unit in a parking lock of an automatic transmission. However, this is not the sole application of the proposed locking unit. It can be used wherever the position of a component moving axially, i.e. parallel to its longitudinal extent, is to be defined, i.e. is to be locked.

In this connection, it is emphasized in particular that all of the features and properties, but also procedures described with respect to the device can expediently also be transferred in respect of the drafting of the method according to the disclosure and can be used within the meaning of the disclosure and are considered to also be disclosed. The same also applies in the opposite direction, that is to say features which are structural, i.e. are according to the device, that are mentioned only with regard to the method can also be taken into consideration and claimed within the scope of the device claims and are likewise included in the disclosure.

DETAILED DESCRIPTION

In the figures, identical or mutually corresponding elements are each denoted by the same reference signs and are therefore not described again, unless expedient. The disclosures contained in the entire description are expediently transferrable to identical parts with the same reference signs or the same component designations. The positional details selected in the description, e.g. top, bottom, laterally, etc. are also related to the directly described and illustrated figure and can expediently be transferred in the event of a change in position to the new position. Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also be independent, inventive solutions or solutions according to the disclosure.

FIG. 1aschematically shows the locking unit1according to the disclosure in a first exemplary embodiment. The locking unit1has a housing5, at the front housing end50of which an opening51is provided from which the front end21of the piston2protrudes.

At the housing end52opposite the opening51, a solenoid3adjoins the housing5in the axial direction. Axial direction means here either the axis of symmetry or longitudinal axis22of the piston2or else the direction of movement of the piston2.

In the housing5, the piston2is mounted movably in the axial direction, in particular along its longitudinal axis22. For the movement of the piston2, a drive is provided here; in particular, the piston2can be acted upon with pressure, preferably with hydraulic pressure, wherein the force component of said pressure is directed counter to the direction of force of a piston spring23. The piston spring23is supported here firstly on a housing step adjoining the housing end50on the inside or on a step53of the housing5. Secondly, the piston spring23is supported on a flange ring24of the piston2. Said flange ring24lies in the interior, centrally in the housing5.

Owing to the pressure, the piston2moves between a plurality of positions; in the variant shown here, for example, two positions are provided. The position of the piston2in the respective positions can be secured by a latching unit4which is equipped with latching elements40. For the actuation of the latching unit4, in particular for the latching elements40thereof, use is made of the solenoid3or use is made of the elements thereof.

The solenoid3has a coil body32which bears a winding33. The latter comprises a wire through which an electrical current can flow. The winding33is closed radially on the outside (with respect to the longitudinal axis22) by a solenoid housing34. Energizing the winding33gives rise to a magnetic field.

An armature space35is provided in the interior of the coil body32, wherein the armature space35here fills approximately half of the interior space of the coil body32. The armature space35is oriented here in the direction of the piston2. The remaining region of the interior space of the coil body32is filled by a solenoid core36which, as customary, is composed of soft magnetic material which readily guides the magnetic field lines. Located in the armature space35is an armature30which, in the exemplary embodiment shown here, is designed in the manner of a cylinder and has a base surface37. An air gap39is formed between the base surface37and an end surface38of the solenoid core36, said end surface facing the armature space35.

If the winding33is not energized, a solenoid spring300pushes the armature30to the right such that the air gap39is at its maximum extent. If the winding33is energized, it generates a magnetic field which pushes the armature30to the left counter to the force of the solenoid spring300such that the air gap39is closed.

The armature30bears an armature rod31. The armature rod31is oriented here concentrically with respect to the armature30, and armature30and armature rod31are mounted movably in the axial direction, i.e. parallel to the longitudinal axis22, in the armature space35. The design is selected here in such a manner that the armature30has an axial bore301which receives the armature rod31. The armature rod31protrudes over the armature30on both sides thereof.

An axial bore302is likewise provided in the solenoid core36. The arrangement is selected in such a manner that a mounting for the armature rod31is located in said axial bore302.

The armature space35is limited on the one side by the solenoid core36, wherein the solenoid core36, as already described, fills that part of the interior space of the coil body32which faces away from the piston2and thus also describes the axial end of the solenoid3, but also of the locking unit1, together with the solenoid housing34.

On the other side, facing the piston2, the armature space35is limited by a yoke part41which is configured in the manner of a cup and is preferably formed from soft magnetic material in order to readily guide the magnetic field lines. Part of the armature30dips here into the yoke part41which is configured in the manner of a cup.

The yoke part41here is part of the latching unit4. The yoke part41has a penetration bore47which receives and optionally also supports the armature rod31.

The latching unit4is substantially H-shaped, as seen in section. The radially oriented web of the H forms the yoke part41. This is adjoined by a first axial portion48and a second axial portion49. The two axial portions48,49of the H adjoining here on both sides of the web differ in size or differ in length, wherein the portion49facing the armature space35is significantly shorter axially than the portion48facing the piston2. The larger portion48here or in typical embodiments is approx. 2 to 3, 3.5 or 4 times larger or longer than the smaller portion49.

An equalizing opening405running radially (with respect to the longitudinal axis22) is arranged in the foot region of the sleeve-like first axial portion48, said foot region facing the yoke part41. Said equalizing opening405fluidically connects an interior space42to an exterior space406in which a piston thrust piece26of the piston2moves axially. Pressure equalization between the interior space42and the exterior space406is possible through the equalizing opening405.

The two portions48,49radially close one corresponding receiving space each. In this case, the smaller second portion49delimits the armature space35(this is the cup-like yoke part41) and the larger portion48delimits the interior space42. The interior space42extends here in the axial direction. The interior space42is also provided with the solenoid spring300which is supported firstly on the upper side of the yoke part41, said upper side facing the second portion49, and secondly on a control element43which is arranged on the end side of the armature rod31. The control element43is arranged here in a positionally fixed manner on the armature rod31.

The control element43also has a receiving bore401into which the armature rod31is inserted. The control element43is compressed in a suitable manner with the armature rod31and thus held in a positionally precise manner on the latter. The control element43essentially consists of two different geometrical bodies, a cylinder portion and a cone portion, wherein the lateral surface of the cone portion forms a cone surface400. A lateral surface403of the cylinder portion of the control element43is guided, optionally also mounted, on an interior space wall402radially bounding the interior space42. Located at the axial end of the control element43, the axial end facing the solenoid3, is an annular recess404in which the end of the solenoid spring300is located and is thus reliably guided and held. The cone surface400is located at that end of the control element43which lies opposite the recess404.

It is clear that other designs are also possible for the configuration of the control element43. For example, it is thus also conceivable that the cone surface is arranged on the control element on the side facing the solenoid3and then the manner of functioning of the locking unit1is optionally changed. The variant shown inFIG. 1ais planned in such a manner that, when the solenoid is currentless, i.e. when the winding33is currentless, the control element forces the latching elements40, which are designed here as balls, radially outward and thus blocks the piston2. However, the movement of the piston2can also be blocked when the solenoid3is energized.

The position of the air gap39is also variable in this case according to the proposal. In the exemplary embodiment shown inFIG. 1a, the air gap39is located on that side of the armature30which faces away from the latching unit4, i.e. between armature30and the solenoid core36. As an alternative thereto, it is also possible for the air gap then to be formed between the armature30and the yoke part41, i.e. that side of the armature30which faces the latching unit4.

The arrangement of the solenoid spring300in the interior space42is advantageous since said elements therefore do not impair the magnetic circuit which is formed in the elements around the armature space35.

Alternatively, an arrangement of the solenoid spring in the armature space or else outside the latching unit4is also possible in order to form a corresponding force accumulator.

When the winding33is energized, the air gap39is closed by the armature30being offset to the left, as a result of which the armature rod31and the control element43carried by the armature rod31are also offset to the left, and therefore the solenoid spring300is compressed and thus forms a force accumulator for a resetting movement of the unit of armature30, armature rod31and control element43when the energizing of the winding33is switched off.

The larger first portion48of the latching unit4bears, at its end or end region44facing away from the yoke part41, the latching element or the latching elements40which are designed here as balls. The larger portion48(at least in the end region44) is formed here in the manner of a sleeve or cylinder. The latching elements40are provided as balls40in a ball cage. The sleeve- or cylinder-like end region44of the portion48has bores45oriented here radially (with respect to the longitudinal axis22) for receiving the latching elements40or balls.

Depending on the axial position of the control element43, it is possible for the latching elements40or balls40to be able to yield radially inwards or not.

In the exemplary embodiment shown inFIG. 1a, the piston2consists of two individual parts. The piston2comprises a piston tube25which partially protrudes out of the opening51, and a piston thrust piece26produced separately from said piston tube. The arrangement is selected here in such a manner that the piston thrust piece26adjoins the inner end of the piston tube25in the housing5.

The piston tube25is completely hollow on the inside. It is preferably formed as a deep drawn part, for example from metal, such as, for example, tool steel or similar, and therefore the production of such an element is made considerably less expensive. The wall thickness of the piston tube25is therefore here also only approx. 5 to approx. 15 percent of the diameter of the piston tube25or of the outside diameter of individual parts (e.g. inner end27, first tube center section29, second tube center section202and connecting region203) of the piston tube25.

The piston tube25lies with its flange ring24provided on the end side against the piston thrust piece26. The flange ring24therefore forms a boundary surface of the piston tube25, said boundary surface being oriented radially (with respect to the longitudinal axis22). Said inner end27which also includes the flange ring24is plugged onto the connecting ring28which closes off the piston thrust piece26in the direction of the piston tube25. A relatively precise fit can be provided here and, for example, the piston tube25can thereby be pressed onto the piston thrust piece26. Of course, other connecting methods, such as, for example, welding, soldering or else adhesive bonding of the elements—piston tube25and piston thrust piece26—are alternatively also possible.

The end27then merges in a tapering200into a first tube center section29, i.e. the diameter of the piston tube25in the region of the first tube center piece29is smaller than in the region of the end27. The first tube center piece29then adjoins the second tube center section202at a further, second tapering201which is designed as a step. The diameter of the piston tube25in the region of the second tube center section202is smaller than in the region of the first tube center section29. Said second tapering201forms a stop.

The piston2is guided in a plain bearing54. The latter has an inner flange55. If the piston2is displaced to the right, the movement is thereby limited by the fact that the shoulder-like tapering201lies on the radially acting inner flange55of the plain bearing54. Such a state is illustrated, for example, inFIG. 2b.

The plain bearing54which has just been mentioned for the piston tube25is provided on the inner side of the opening51of the housing5. The second tube center section202is mounted on said plain bearing54. The plain bearing54has an inner flange55which is oriented into the housing interior and also forms the step53in this region. Since the housing5is preferably composed of plastic, this part is correspondingly oversprayed. However, it is also possible for the plain bearing54to be inserted into a separately produced, for example sprayed, housing5, such as, for example, a plastics housing. Relatively high accuracy is preferably favorable here, per certain embodiments, i.e. in the region of the opening51and of the embedding of the plain bearing54in the housing5.

In the position shown here of the locking unit1, the piston2is pushed completely into the housing5and only the end-side connecting region203of the piston2protrudes out of the housing5. Further elements, not shown here, which are moved or held by the piston2are connected to the piston2in the connecting region203. The second tube center section202merges here in the third tapering204into the connecting region203.

As already explained, all of the axial portions, i.e. the inner end27, the first tapering200, the first tube center section29, the second tapering201, the second tube center section202, the third tapering204and the connecting region203are hollow on the inside.

It should be noted that the connecting region203has a recess provided on the center plane, i.e. is slotted. A fork-like structure of the connecting region203is formed, wherein remaining half shells211of the connecting region203nevertheless provide sufficient stability for the connection to a further element, not illustrated specifically. In order to receive a fastening bolt or similar, a respective bore or other penetration opening210is provided in the half shell211.

The piston thrust piece26is likewise formed substantially in the manner of a sleeve, i.e. hollow on the inside. Its outer surface205is used for guidance. At the front end facing the piston tube25, an outer ring206is provided on the piston thrust piece26. The outer surface of said outer ring is mounted, but at least guided, on a housing inner wall56. The outer ring206lies in the axial direction (with respect to the longitudinal axis22) against the flange ring24of the piston tube25. A pressure side207of the outer ring206, which pressure side faces away from the flange ring24, is acted upon with pressure, preferably with hydraulic pressure, and is therefore also of correspondingly solid design. An annular pressure space70is provided here.

The piston thrust piece26is therefore preferably, according to an embodiment, realized as a turned part. It is preferably composed of tool steel per an embodiment. An encircling step208which receives an O ring seal or a sealing ring209is provided radially on the outside of the pressure side207. Since said O ring seal or the sealing ring209is exposed to the hydraulic pressure, it is also pressed in the radial direction and thus reliably closes a gap which perhaps still remains between the radial outer surface of the outer ring206and the housing inner wall56.

Furthermore, a center section6is provided. The center section6is likewise designed in the manner of a sleeve and its inner side forms a bearing surface60for the piston thrust piece26. The bearing surface60interacts here with the lateral surface or outer surface205of the piston thrust piece26. The center section6is positionally fixed in the locking unit1. For example, the center section6is provided as a turned part and is preferably composed of a customary tool steel. In a further embodiment, it is provided that the center section6is designed as a sintered shaped part or is manufactured in a formative method, in particular by means of 3D printing, metal powder injection molding, selective laser melting or selective laser sintering. Sintering or formative manufacturing are cost-effective production methods with which in addition workpieces shaped virtually as desired can be produced in a single working cycle.

The center section6has an axial length (with respect to the longitudinal axis26) depending on other components of the proposed locking unit1.

The axial length of the center section6corresponds here to approx. 100-200%, preferably approx. 130-170%, of the stroke of the piston2.

The axial length of the center section6corresponds here to approx. 20-50%, preferably approx. 30-40%, of the axial length of the piston2.

The axial length of the center section6corresponds here to approx. 10-30%, preferably approx. 13-20%, of the axial length of the locking unit1.

The outer surface205here is the lateral surface of a cylinder. The outer surface205bears a further O ring seal213in a circumferential groove212at its end facing away from the piston tube25and facing the solenoid3. Said O ring seal213seals the gap which remains between the outer surface205and the bearing surface60and is pressurized, in the direction of the solenoid3.

The piston2shown inFIG. 1aconsists of the two components, the piston tube25and the piston thrust piece26, which are fixedly connected mechanically to each other in the variant shown here because, for example, they are plugged on or compressed. However, they can alternatively also be formed in a floating manner with respect to each other, i.e. can be pressed against each other only because of the dynamic effect of the applied pressure, on the one hand, and the counter-directed force of the piston spring23, on the other hand.

Said piston2which consists of two components is first of all mounted on the bearing surface60of the center section6by means of the piston thrust piece26. A further mounting is alternatively provided on the outer ring206of the piston thrust piece26in cooperation with the housing inner wall56. Ultimately, the second tube center section202of the piston tube25is mounted on the plain bearing54provided on one side.

An inner surface214of the piston thrust piece26is also not smooth, but rather has indentations or latching receptacles20,20a,20bon the end side in each case, i.e. spaced apart axially from one another (with respect to the longitudinal axis22). The diameter of the ring-like indentations or latching receptacles20,20a,20bis larger here than the diameter of the inner surface214lying between them.

The latching receptacles20,20a,20bare turned into the inner surface214of the sleeve-like piston thrust piece26in the form of a step or inner shoulder. The latching unit4is arranged in the housing5in a positionally fixed manner, and the piston2is designed to be axially or longitudinally movable in relation to the latching unit4. However, in the position shown inFIG. 1a, the movement of the piston2to the right, in the direction of the opening51, is blocked by the latching unit4; the locking unit1is blocked in the retracted position of the piston2.

As already mentioned, the latching unit4has latching elements40, here, for example, balls40of a ball cage, which are mounted in respective bores45so as to be movable radially (with respect to the longitudinal axis22). The solenoid3is shown in a dropped position, i.e. the winding33is not acted upon with current. The air gap39is therefore formed between the armature30and the solenoid core36since the solenoid spring300offsets the armature30to the right and therefore also the control element43on which the solenoid spring300is indeed supported. The control element43therefore passes onto the axial position of the latching elements/balls40, and therefore the cone surface400of the control element43acts on the latching elements/balls40and pushes the latter radially outwards (with respect to the longitudinal axis22) into the respective latching receptacles20,20a. Then, however, a longitudinal movement of the piston2, i.e. a movement of the piston2to the right, is blocked since a first inner shoulder215awhich bounds the latching receptacle20,20alies against the latching elements40which are offset radially outward. The first inner shoulder215ais located here on the first latching receptacle20a, on the side facing the second latching receptacle20b.

In the position shown inFIG. 1a, that end of the piston thrust piece26which faces away from the piston tube25furthermore lies against a radially running stop surface61of the center section6and thus also blocks a movement of the piston2to the left, in the direction of the solenoid3.

For the sake of completeness, reference should also be made at this juncture toFIG. 2bwhich shows the position in which the piston2is extended to the right completely out of the housing5. This end position is firstly limited by the second tapering201lying against the inner flange55of the plain bearing54in the region of the opening51of the housing5. In this position, the solenoid3is in turn switched off, i.e. the winding33is not acted upon with current, and therefore the control element43pushes the latching elements/balls40into the outer or second latching receptacle20,20bof the piston thrust piece26and thus on the other hand blocks a movement to the left. The radially pushed-out latching elements/balls40then lie against a second inner shoulder215bwhich bounds the second latching receptacle20b. The second inner shoulder215bis located here on that side of the second latching receptacle20bwhich faces the first latching receptacle20a. As already described, the two latching receptacles20aand20bare spaced apart from each other axially (with respect to the longitudinal axis22).

The piston2, in particular the piston thrust piece26, is mounted movably between the latching unit4arranged radially on the inside and the center section6arranged radially on the outside. In the embodiment shown, the center section6takes up a central position in the locking unit1. On the one hand, the radial outer side62of said center section bears the sleeve-like housing5. However, on the other hand, it also produces a connection to the solenoid3, in particular to the solenoid housing34thereof.

In the lower region inFIG. 1b, a radially running gap65can be seen between the solenoid housing34and the housing5, said gap extending radially on the inside into a channel66awhich is in fluidic contact with an interspace66bwhich arises between the thrust piece26and the latching unit4. The radially running channel66ais realized here in such a manner that a recess67(seeFIGS. 3aand 3b) is provided on a foot region68(seeFIGS. 3aand 3b) of the center section6, the foot region facing the solenoid3, and therefore the foot region68of the center section6, said foot region facing the solenoid3, does not lie over the entire extent against the flange part of the coil body32. The fluidically interconnecting elements of interspace66b, channel66aand gap65permit venting of the interior of the locking unit1.

Furthermore, the center section6orients the solenoid3radially with respect to the latching unit4. It is favorable to realize a high degree of concentricity in this region.

The center section6, on its side facing away from the solenoid3or facing the piston tube25, has an encircling contact shoulder63which is then adjoined by an annular and/or conical connecting region64.

Said connecting region64is a constituent part of the center section6. The proposal according to an embodiment of the disclosure is highly variable for the configuration of the connecting region64. The connecting region64here has a plurality of tasks.

First of all, said connecting region supports a tube section57which may also be referred to as a sleeve section, which is part of the housing5and the inner side of which provides the housing inner wall56. Furthermore, at least part of the connecting region64limits the pressure space70, i.e. is in contact with the pressurizable medium. For this purpose, the tube section57is pushed or pressed onto the preferably annular region of the connecting region64. As already described, the piston2, in particular the piston thrust piece26, lies against the housing inner wall56; in this respect, the tube section57has the properties of a cylinder. The tube section57preferably limits or conducts the pressure not only on its housing inner wall56, but also on its tube outer side58.

The mounting of the first end piece of the tube section57on the center section6underlines the suitability of the center section6in the embodiment shown here. The second end piece of the tube section57is mounted in the housing5, and the inner side of the tube section57serves as a mounting or guide of the piston2.

In the present embodiment, the tube section57is connected in a fluid-tight manner to the housing5on the right side. This is brought about by the fact that the tube section57is pushed into a groove80of the housing5. The groove80is of annular design here and is limited radially on the inner side by a projection81of the housing5. It is ensured by means of the connection of fluid-tight design that fluid which is under pressure and which is located in the pressure conducting channel71does not pass at the connecting point between housing5and tube section57into a region radially on the outer side of the piston tube25, which would counteract a movement of the piston2to the right, which is intended to be achieved specifically by means of the fluid under pressure, as described below. Possible embodiments of a tight connection are illustrated inFIGS. 4ato 4cand will be described further below.

A pressure connection, not illustrated specifically inFIG. 1a, which provides a pressurized medium as the drive for the piston2is located on the housing5. Said pressure connection is preferably arranged, per an embodiment, in that half of the housing5which faces the opening51; in particular, it is situated close, in particular very close, to the opening51. In order now to realize as large a stroke of the piston2as possible, the pressure side207, which can be acted upon with pressure, of the piston thrust piece26has to be removed as far as possible from the opening51in the retracted position of the piston2. This boundary condition leads to the pressurized medium first of all having to be conducted in the housing5or in the locking unit1counter to the preferred direction of movement (the working movement realized by the pressurization, to the right inFIG. 1a) of the piston2in order then to be deflected at a suitable point and guided onto the pressure side207.

The pressure connection, not shown, is therefore fluidically connected to the pressure conducting channel71running substantially axially (with respect to the longitudinal axis22). Said pressure conducting channel71is limited radially on the inside by the outer side58of the tube section57and radially on the outside by the plastics housing5, in particular the inner wall500thereof. The pressure conducting channel71can surround the entire tube section57(with respect to its circumferential direction) or can extend axially only in one segment, as shown inFIG. 1a.

Since the tube section57according to one embodiment is plugged fixedly, and therefore also tightly or in a pressure-tight manner on the connecting region64of the center section6, an aperture501is provided at the axial height, with respect to the longitudinal axis22, of the connecting region64in the tube section57, through which aperture the pressurized medium passes out of the pressure conducting channel71into the pressure space70on the inner side of the tube section57.

The tube section57therefore has a plurality of tasks.

Its housing inner wall56serves as a guide or mounting of the piston2. Its outer side58serves at least partially as the pressure conducting channel71.

Furthermore, the tube section57supports or reinforces the housing5which is preferably composed of plastic per an embodiment. This combined construction of the housing5combines a low mass and favorable production with a high degree of wear resistance and therefore with high availability of a locking unit configured in such a manner.

The end59of the tube section57that faces away from the connecting region64is surrounded annularly by the plastics material of the housing5. The pressure conducting channel71therefore does not inevitably extend over the entire axial length of the tube section57. For example, the tube section57can be insert molded by the plastic of the housing5; alternatively, for example, the tube section57can be plugged or pressed into a housing5produced in a separate manufacturing step.

FIGS. 3a, 3bshow an exemplary embodiment of the center section6. A center section6configured in such a manner is also found in the use example according toFIG. 2aor2b.

The center section6is formed in the manner of a sleeve. In the installed state, it has a foot region68which faces the solenoid3and is adjoined by a center portion69. On the side facing away from the foot region68, the center section6is closed by a connecting region64. The center portion69has the largest diameter and, in the installed state, lies directly against the plastics material of the housing5.

The diameter of the foot region68is smaller than the diameter of the center portion69. The foot region68is not completely configured as an encircling ring, but rather has, in a certain angular segment, a recess67which, in the installed state, forms the channel66a. The center portion69merges with the radially running contact shoulder63into the connecting region64.

The outside diameter of the connecting region64is also smaller than the diameter of the center portion69. The tube section57is plugged onto the connecting region64in the installed state. For this purpose, the connecting region64is provided with a multiplicity of supporting segments600which are designed as lateral segments on the cylinder-like outer surface of the connecting region64and are each separated by segment interspaces72. Said segment interspaces72are formed as clearances in the lateral surface of the connecting region64and guide the medium; that is to say, in the installed state and during operation, the corresponding operating pressure prevails in the segment interspaces72. The segment interspaces72are therefore part of the media-guiding system.

The exemplary embodiment of the center section6according toFIG. 1aor1bdiffers with respect thereto as follows:

As already explained, there is a fluidic connection between the pressure conducting channel71, which is arranged on the radial outer side of the tube section57, and the pressure space70, which is arranged on the radial inner side of the tube section57. In the example shown inFIGS. 1aand 1b, said connection is realized by the aperture501in the tube section57. That end502of the tube section57which faces the center section6is pushed here completely onto the connecting region64and lies fully (and therefore also in a sealing manner) against the radially outwardly running contact shoulder63.

FIGS. 2aand 2bshow the use of the center section6according toFIGS. 3aand 3b. It can readily be seen that the end502facing the center section6is spaced apart axially (with respect to the longitudinal axis22) from the contact shoulder63. The segment interspaces72extending in the axial direction (with respect to the longitudinal axis22) are therefore fluidically connected to the pressure conducting channel71and also to the pressure space70. The axial distance (with respect to the longitudinal axis22) of the tube end502from the contact shoulder63corresponds here to the aperture501and here forms a radial connection from the inner side of the tube section57to the outer side of the tube section57. This connection runs here outside the tube section57, i.e. offset axially outward, with respect to the tube section end502.

FIGS. 2aand 2beach show, in a vertical section, a second exemplary embodiment of the locking unit1according to the disclosure in two different positions of the piston.

InFIG. 2a, the piston2is completely retracted in the locking unit1and is secured in said end position by the latching unit4. The completely retracted position of the piston2results from the fact that the piston thrust piece26is exposed only to a small pressure, if any pressure, which generates a force which is smaller than the opposite spring force of the piston spring23. InFIG. 2b, the piston2is completely pushed out of the locking unit1and is likewise secured in said end position by the latching unit4.

As already explained, the blocking position of the latching unit4is realized in the dropped, i.e. non-energized, state of the solenoid3, but without the disclosure being set thereto; the blocking position can alternatively also be realized in the energized state of the solenoid.

In order, for example, now to move the piston2from the position shown inFIG. 2ainto the position shown inFIG. 2b, the procedure can be as follows, according to an embodiment.First of all, the blockage of the latching unit4should be eliminated. This takes place by the solenoid3being energized and, as a result, the unit of armature30, armature rod31and control element43being offset axially and thus permitting radial movability of the latching elements/balls40which can then, for example, yield back radially inward and thus permit the axial movement (all with respect to the longitudinal axis22) of the piston2, here in particular of the piston thrust piece26.In the next step, a drive of the piston2, here, for example, a hydraulic pressurization, is activated and the operating pressure prevailing on the piston thrust piece26then pushes the piston2, consisting of the piston tube25and the piston thrust piece26, to the right counter to the force of the piston spring23, away from the solenoid3. The piston tube25is thereby pushed out of the opening51.The end position thus achieved of the piston2is then secured again by the latching unit4; for this purpose, the current through the winding33of the solenoid3is switched off or is at least so greatly reduced that the resulting magnetic force on the armature30is lower than the spring force of the magnetic fields300acting counter to the magnetic force. The dropping armature30shifts the control element43axially in such a manner that the cone surface400thereof pushes the latching elements/balls40radially outward into the latching receptacle20and thus prevents the piston2from yielding back, for example when pressure on the piston thrust piece26is switched off.

FIGS. 4ato 4ceach show a detail of the connecting point between tube section57and housing5, wherein different possibilities of the fastening and sealing are described.

As already mentioned further above, the tube section57is accommodated in a groove80which is formed annularly and is bounded radially on the inner side by a projection81.

In the embodiment ofFIG. 4a, a seal82in the form of a sealing ring is arranged between housing5and tube section57. Said seal ensures a fluid-tight design.

In the embodiment ofFIG. 4b, a seal83in the form of sealing material made of silicone, the sealing material ensuring the fluid-tight design, is arranged laterally of the tube section57. The tube section57can therefore also be held in the groove80.

In the embodiment ofFIG. 4c, a number of bores84are formed in the tube section, through which bores a respective engagement part85of the housing5passes. This can take place, for example, by the fact that the housing5is sprayed around the tube section57during manufacturing. The engagement part85can therefore be connected in particular in a material bonded manner to the rest of the housing5and can therefore ensure a suitable fastening of the tube section57.

Alternatively, it is also clear that the end of the tube section57can be insert molded even without the arrangement of bores84. For example, at least at the end of the tube section57, the plastics material of the housing5can lie here against said tube section on the inside (by means of the projection81) and on the outside.

FIG. 5shows a locking unit1according to a third exemplary embodiment. Essentially the differences over the exemplary embodiments already described will be discussed below. Otherwise, reference should be made to the description which has already been provided.

As already explained in the previously described exemplary embodiments, the piston2is hollow, and therefore a cavity220is formed in the piston2. Said cavity is divided into a first cavity region221and a second cavity region222. The first cavity region221is arranged in the piston thrust piece26. The second cavity region222is arranged in the piston tube25.

A filter unit500is arranged between the first cavity region221and the second cavity region222. Said filter unit has an outer annular edge510with which it is fastened, as shown, in the piston2, specifically between piston tube25and piston thrust piece26. Arranged internally with respect to the annular portion510is a cup-shaped region520, on the end side of which a filter530is arranged.

The annular edge510and the cup-shaped region520ensure in particular that the first cavity region221and the second cavity region222are sealed fluidically in relation to each other within the piston2apart from the filter530. This prevents fluid from flowing elsewhere than through the filter530between the two cavity regions221,222and thus transporting dirt particles without filtering.

The filter530ensures that an exchange of fluid between the two cavity regions221,222is possible, but an exchange of dirt particles is prevented. For this purpose, the filter has a multiplicity of pores, the respective size of which is selected in such a manner that fluidic exchange is possible, but dirt particles which are typically to be expected are kept away. In particular, dirt particles which possibly penetrate into the piston2from the right side ofFIG. 5, i.e., for example, originate from connected or actuated components, can thereby be kept away from the elements bringing about the latching.

It should be pointed out that, in the embodiment ofFIG. 5, the center section6and the latching unit4are formed integrally. This feature leads to particularly simple production and high stability, but is functionally independent of the use of a filter, as just described.

Possible features of the proposal are reproduced in structured form below. The features reproduced in structured form below can be combined with one another as desired and can be incorporated in any combination into the claims of the application. It is clear to a person skilled in the art that the disclosure already arises from the subject matter having the fewest features. In particular, advantageous or possible refinements, but not the only possible refinements of the disclosure, are reproduced below.

The disclosure comprises:

A locking unit, in particular for the parking lock of an automatic transmission, for locking the movement of a piston (2) which is movable by a drive, and in particular can be acted upon with pressure or hydraulic pressure, the locking unit (1) having a solenoid (3) and at least one latching element (40), and the latching element (40) interacting with the armature (30) or the armature rod (31) of the solenoid (3), and the piston (2) having at least one latching receptacle (20,20a,20b), and the piston (2) being securable by the retaining interaction of the latching element (40) with the latching receptacle (20,20a,20b), wherein the piston (2) is at least partially mounted in a center section (6) which is at least partially surrounded by a housing (5), wherein the locking unit (1) has a latching unit (4) which supports the latching elements (40), wherein the latching unit (4) and the center section (6) are formed integrally.

The abovementioned locking unit, wherein the center section (6) is designed in the manner of a sleeve.

The abovementioned locking unit, wherein an inner side of the center section (6) forms a bearing surface for the piston (2) or for a piston thrust piece (26) of the piston (2).

The abovementioned locking unit, wherein the center section (6) is in the form of a turned part or sintered shape part, is produced in a formative method or is produced by means of 3D printing, metal powder injection molding, selective laser melting or selective laser sintering.

The abovementioned locking unit, wherein the center section (6) has an axial length of 100% to 200% or of 130% to 170% of a stroke of the piston (2).

The abovementioned locking unit, wherein the center section (6) has an axial length of 30% to 40% of an axial length of the piston (2).

The abovementioned locking unit, wherein the center section (6) has an axial length of 13% to 20% of an axial length of the locking unit (1).

The abovementioned locking unit, wherein the piston (2) is hollow on the inside completely along its axial extent.

The abovementioned locking unit, wherein the piston (2) has a cavity which extends axially through the entire piston (2).

The abovementioned locking unit, wherein the cavity is open at both axial ends.

The abovementioned locking unit, wherein the cavity continuously or in sections has a wall which is thinner than a quarter of a diameter of the piston (2) or is thinner than a tenth of the diameter of the piston (2).

The abovementioned locking unit, wherein the piston (2) has a completely hollow piston tube (25) along an axial portion and a piston thrust piece (26), which is connected to the piston tube (25), along a further axial portion.

The abovementioned locking unit, wherein the latching receptacles (20,20a,20b) are formed in the piston thrust piece (26).

The abovementioned locking unit, wherein the piston tube (25) is in the form of a deep drawn part, from tool steel or from metal.

The abovementioned locking unit, wherein the piston tube (25) has a wall thickness of 5% to 15% of the diameter of the piston tube (25).

The abovementioned locking unit, wherein the piston (2) is at least partially mounted in the housing (5).

The abovementioned locking unit, wherein the housing (5) is entirely or partially formed from plastic.

The abovementioned locking unit, wherein the piston tube (25) has a tube center section (29) with an outer tapering (201), wherein the tapering (201) of the piston tube (25) interacts with a step (53) formed in the housing (5), in order to limit a movement of the piston (2) away from the solenoid (3).

The abovementioned locking unit, wherein a piston spring (23) is provided between housing (5) and piston (2) and pushes the piston (2) in the direction of the solenoid (3).

The abovementioned locking unit, wherein the piston (2) is mounted opposite the solenoid (3) in a plain bearing (54) of the housing (5).

The abovementioned locking unit, wherein the housing (5) has an internal tube section (57), wherein a pressure conducting channel (71) is formed on the outer side of the tube section (57).

The abovementioned locking unit, wherein the pressure conducting channel (71) is connectable hydraulically from the outside via a connection through the housing (5).

The abovementioned locking unit, wherein the center section (6) has a radial outer side (62) which supports the housing (5).

The abovementioned locking unit, wherein the center section (6) is connected to a solenoid housing (34) of the solenoid (3).

The abovementioned locking unit, wherein the center section (6) has an encircling contact shoulder (63) on its side facing away from the solenoid (3) and/or facing the piston tube (25), which contact shoulder is adjoined by an annular and/or conical connecting region (64).

The abovementioned locking unit, wherein the connecting region (64) supports the tube section (57).

The abovementioned locking unit, wherein a number of segment interspaces (72) are designed as notches radially on the outer side in the connecting region (64).

The abovementioned locking unit, wherein the segment interspaces (72) are designed as a fluidic connection between pressure conducting channel (71) and a pressure space (70) within the tube section (57).

The abovementioned locking unit, wherein respective supporting segments (600) which support the tube section (57) are formed between the segment interspaces (72).

The abovementioned locking unit, wherein the connecting region (64) is designed as a crown ring.

The abovementioned locking unit, wherein the latching unit (4) has a portion (49) facing the solenoid (3) or an armature space (35) of the solenoid (3) and a portion (48) facing the piston (2), which portions are each of sleeve-shaped design.

The abovementioned locking unit, wherein that portion (49) of the latching unit (4) which faces the solenoid (3) partially accommodates the armature (30) in at least one end position.

The abovementioned locking unit, wherein an interior space (42) which is open on the piston side is formed in the latching unit (4) or in that portion (48) of the latching unit (4) which faces the piston (2).

The abovementioned locking unit, wherein an exterior space (406) is formed between latching unit (4) and housing (5) or between latching unit (4) and center section (6).

The abovementioned locking unit, wherein exterior space (406) and interior space (42) are fluidically connected via an equalizing opening (405) formed in the latching unit (4).

The abovementioned locking unit, wherein the exterior space (406) is vented by a channel (66a) which is formed in or on the center section (6).

The abovementioned locking unit, wherein the latching unit (4) is fixedly connected directly or indirectly to the housing (5).

The abovementioned locking unit, wherein a control element (43) which is fixedly connected to the armature rod (31) is arranged in the latching unit (4).

The abovementioned locking unit, wherein the control element (43) is at least partially movable within the portion (48) facing the piston (2).

The abovementioned locking unit, wherein a number of radial bores (45) for receiving the latching elements (40) are formed in the latching unit (4).

The abovementioned locking unit, wherein the latching elements (40) are of spherical design.

The abovementioned locking unit, wherein the control element (43) is designed in order, at least in one position, to push the latching elements (40) radially outward.

The abovementioned locking unit, wherein the latching elements (40), when they are pushed radially outward, come into engagement with one of the latching receptacles (20,20a,20b).

The abovementioned locking unit, wherein the piston (2) has at least two latching receptacles (20a,20b) which are spaced apart axially from one another.

The abovementioned locking unit, wherein the piston (2) is lockable in two different positions by means of the two latching receptacles (20a,20b).

The abovementioned locking unit, wherein the solenoid (3) has a solenoid core (36) which is arranged at one axial end of the locking device (1).

The abovementioned locking unit, wherein the armature rod (31) is guided in a bore of the solenoid core (36).

The abovementioned locking unit, wherein the piston (2) has a connecting region (203) which is on the end side axially and protrudes from the housing (5) even in the completely retracted state of the piston (2).

The abovementioned locking unit, wherein the connecting region (203) is designed in the manner of a fork.

The abovementioned locking unit, wherein the connecting region (203) is designed as a punched-out fork head.

The abovementioned locking unit, wherein the piston (2) or the piston thrust piece (26) is at least partially arranged radially between latching unit (4) and housing (5) or is arranged between latching unit (4) and center section (6).

The abovementioned locking unit, wherein the solenoid has a winding (31) for generating a magnetic field for moving the armature (30) and/or the armature rod (31).

The abovementioned locking unit, wherein the inner tube section (57) is designed as a guide of the piston (2).

The abovementioned locking unit, wherein the pressure conducting channel (71) is limited at least partially radially, with respect to the longitudinal axis (22) of the piston (2), on the inside by the outer side of the tube section (57) and on the outside by the inner wall (500) of the housing (5).

The abovementioned locking unit, wherein the tube section (57) is connected to the housing (5) or is part of the housing (5).

The abovementioned locking unit, wherein the piston (2) lies against the tube section (57).

The abovementioned locking unit, wherein the piston (2) slides along the tube section (57).

The abovementioned locking unit, wherein the piston (2) lies in a fluid-tight manner against the tube section (57).

The abovementioned locking unit, wherein the piston (2) has a sealing means which seals the piston (2) on the tube section (57) in a fluid-tight manner.

The abovementioned locking unit, wherein the sealing means is a sealing ring (209) or an O ring.

The abovementioned locking unit, wherein the sealing ring (209) or the O ring is provided in an encircling step (208) of the piston (2).

The abovementioned locking unit, wherein the sealing ring (209) or the O ring is provided in a piston thrust piece (26) of the piston (2).

The abovementioned locking unit, wherein the inner side of the tube section (57) forms a housing inner wall (56) against which the piston (2) lies.

The abovementioned locking unit, wherein the tube section (57) is of rectilinear and/or cylindrical design at least along a portion on which the piston (2) is guided.

The abovementioned locking unit, wherein the tube section (57) is formed from metal or from plastic.

The abovementioned locking unit, wherein the center section (6) is designed in the axial direction, with respect to the longitudinal axis (22) of the piston (2), to be shorter on the piston side than the latching unit (4) and in particular the radial bores (45) of the latching unit (4) are not concealed in the radial direction, with respect to the longitudinal axis (22) of the piston (2), by the center section (6).

The abovementioned locking unit, wherein the inner tube section (57) is connected in a fluid-tight manner to the housing (5).

The abovementioned locking unit, wherein the tube section (57) is accommodated in a groove (80) of the housing (5).

The abovementioned locking unit, wherein the groove (80) of the housing (5) is of annular design.

The abovementioned locking unit, wherein a seal (82,83) is arranged between housing (5) and tube section (57).

The abovementioned locking unit, wherein the seal (82,83) is arranged in the groove (80).

The abovementioned locking unit, wherein the seal (82) is an O ring or sealing ring.

The abovementioned locking unit, wherein the seal (83) is a sealing material or a silicone sealing material.

The abovementioned locking unit, wherein a number of bores (84) in which engagement parts (85) of the housing (5) engage is formed in the tube section (57).

The abovementioned locking unit, wherein the housing (5) has an in particular annular projection (81) which partially engages around the tube section (57).

The abovementioned locking unit, wherein the projection (81) limits the groove (80) radially on the inside.

The abovementioned locking unit, wherein the tube section (57) is connected to the housing (5) in a gas-tight and/or pressure-tight manner.

The abovementioned locking unit, wherein the housing (5) supports the tube section (57).

A method for producing a locking unit as described above, wherein the tube section is provided and the housing is insert molded around the tube section.

The abovementioned method, wherein a groove into which the tube section is subsequently introduced is formed in the housing.

The abovementioned method, wherein a number of bores is formed in the tube section, wherein a number of engagement parts which each engage in a bore has been formed or is formed in the housing.

The claims which are filed at this point with the application and claims filed later are without prejudice to the purpose of achieving further protection.

Should it be found here upon closer examination, in particular also of the relevant prior art, that one feature or another, although advantageous, is not absolutely imperative in relation to the aim of the invention, then, of course, the attempt will be made to achieve a wording which no longer has such a feature, in particular in the main claim. Such a sub-combination is also covered by the disclosure of this application.

It should also be noted that the refinements and variants of the invention that are described in the various embodiments and shown in the figures can be combined with one another in any desired manner. It is possible for individual features, or a number of features, to be interchanged as desired. These combinations of features are likewise disclosed here.

The dependency references given in the dependent claims relate to the further development of the subject matter of the main claim by means of the features of the respective dependent claim. However, these should not be understood as obviating the need to achieve independent substantive protection for the features of the appended dependent claims.

Features which have been disclosed only in the description, or also individual features from the claims which comprise a number of features, can at any time be adopted in the independent claim/claims as being of importance which is essential for the purpose of distinguishing the invention from the prior art, to be precise even when such features have been mentioned in conjunction with other features or achieve particularly advantageous results in conjunction with other features.