DE102018110029B4 - Hydraulic tensioning device for a chain drive - Google Patents

Abstract

Hydraulic tensioning device (1) for a chain drive with a tensioning piston (9) which is guided in a receptacle (10) and which has locking grooves (11) on its outer circumferential surface, and with a locking element (12) which has two annular sections (13) and which has an open and a closed radial extension (14a, 14b), wherein the locking element (12) can be brought into engagement with one of the locking grooves (11) with the aid of the two annular sections (13), as well as with a clamping stop (15) , a first sliding stop (16a) and a second sliding stop (16b), wherein the clamping stop (15) and the sliding stops (16a, 16b) are axially spaced from each other and form a clamping stop plane (32) and a sliding stop plane (33) and wherein the receptacle (10) has two axial extensions (17) which extend in the axial direction between the clamping stop plane (32) and the sliding stop plane (33), characterized in that one of the two axial extensions (1 7), the first or second sliding stop (16a, 16b) assigned to this axial extension provided for the formation of a transport lock and a transport lock groove (54) of the tensioning piston (9) form a receptacle for a transport lock wire (20).

Description

The invention relates to a hydraulic tensioning device for a chain drive with a tensioning piston which is guided in a receptacle and which has latching grooves on its outer circumferential surface, and with a latching element which has two annular sections and which has an open and a closed radial extension, the latching element with the aid of the two annular sections can be brought into engagement with one of the locking grooves, as well as with a clamping stop and a sliding stop which are axially spaced from one another, the receptacle having two axial extensions that extend in the axial direction between the clamping stop plane and the sliding stop plane and wherein the two axial extensions of the receptacle and the clamping piston do not include the two radial extensions of the locking element.

Such a tensioning device disclosed for example DE 10 2016 207 784 A1 . The clamping piston is secured against falling out during transport and assembly by means of a transport safety wire. For this purpose, the transport securing wire is inserted into a bore in the housing so that the tensioning piston is fixed by means of a transport securing wire resting on a locking groove in the tensioning piston. In some applications it may be desirable to be able to dispense with a hole for the transport securing wire.

It is therefore the object of the invention to provide an inexpensive transport lock.

The object is achieved by a hydraulic clamping device with the features of claim 1.

Accordingly, one of the two axial extensions, the first or second sliding stop associated with this axial extension - provided to form a transport lock, and a transport lock groove of the tensioning piston form a receptacle for a transport lock wire. The transport safety wire, for example designed as a transport locking pin, is thus held between the tensioning piston and the axial extension in the transport locking groove, in that the mobility of the transport locking wire is limited on the one hand by the axial extension and on the other hand by a section of the sliding stop. The tensioning piston is pretensioned to the outside by a spring and brings the transport securing wire seated in the transport securing groove into contact with the section of the sliding stop; At the same time, a power flow is established between the spring-loaded piston, the transport safety wire and the area of the slide stop. The receptacle designed in this way for the transport securing wire can be produced together with the receptacle by casting, so that a subsequent drilling, for example, can be dispensed with.

The transport securing groove can also be a locking groove. The closed radial extension relates to an area of the locking element without interruption, the open radial extension relates to an area of the locking element in which the ends are located. The open radial extension thus contains an interruption in the locking element, e.g. the ends of a wire shaped into a locking element. The wire ends can overlap, creating a closed contour. The locking element can therefore be pressed apart at the open radial extension, the pivot point is located in the area of the closed radial extension.

The two axial extensions of the receptacle and the tensioning piston do not include the two radial extensions of the locking element; the locking element is therefore not located radially between an axial extension and the tensioning piston. In any case, two of the two axial extensions of the receptacle and the tensioning piston do not include two of the two radial extensions of the latching element in the radial direction, since the radial extensions of the latching element are arranged in the area of the axial extensions of the receptacle. In an advantageous manner, complex machining of the inner circumference of the receptacle can be dispensed with. In contrast to the conventional arrangement of the locking element between the tensioning piston and the housing, no circumferential groove arranged on the inner circumference has to be provided. For example, it can thus be made possible to dispense with machining post-processing in this regard. Instead, for example, the receptacle and the two axial extensions can be produced together by casting.

Particular advantages with regard to the casting production of the receptacle and the axial extensions of the receptacle can be achieved if the underside of an axial extension (i.e. the side facing the clamping piston) is arranged at a certain radial distance from the cylindrical cavity of the receptacle is (or an imaginary extension of the inner surface of the cylindrical cavity). The distance should be greater than 1 mm and preferably between 2 mm and 3 mm. In this way, the receptacle can be produced inexpensively with the aid of an open-close tool and a slide, for example.

A first end and a second end of the latching element enclose the interruption, wherein - at least in a non-pretensioned state of the latching element - in the circumferential direction the distance between the first end and the second end is greater than between subregions of the latching element that form the constriction. The clamping device can therefore be installed in such a way that the locking element is pushed in an axial area between the clamping stop plane and the sliding stop plane in the radial direction over the first of the two axial extensions and then over the clamping piston and the second of the two axial extensions.

In a further embodiment, the tensioning piston is guided in a receptacle and, together with the receptacle, encloses a high-pressure chamber. Hydraulic fluid under pressure reaches the high-pressure chamber via a check valve designed as a refill valve with a check valve body, for example, spherical or plate-shaped. If a force is exerted via the control drive, in particular the chain drive, on the tensioning piston which is pretensioned against the receptacle by means of a spring, the tensioning piston is forced into the receptacle; Vibrations in the timing drive are dampened by draining hydraulic fluid through a leakage gap. A pressure relief valve can be arranged in the high-pressure chamber to reduce pressure peaks.

In order to be able to ensure sufficient tension in the chain, the tensioning piston is, in a further embodiment, braced against the receptacle by means of a spring. For example, when the engine is started, however, large forces can act on the tensioning piston, so that excessive retraction of the tensioning piston cannot be effectively prevented. In order to avoid excessive retraction of the tensioning piston, the tensioning piston has locking grooves on its outer circumferential surface at least along an axial section. The locking grooves are arranged circumferentially along the outer circumference and are designed in such a way that the tensioning piston can be extended but the tensioning piston is prevented from retracting: The locking grooves each have two groove walls which, with the aid of the locking element, come into contact with the clamping stop on the one hand and the sliding stop on the other can be brought. The groove wall, which can be brought into contact with the clamping stop when retracting, runs steeper than the opposite groove wall, which can be brought into contact with the sliding stop. Excessive retraction is effectively prevented in this way, because the latching element rests positively between the latching groove and the clamping stop. When the tensioning piston is extended, the locking element can be brought into contact with the sliding stop, as a result of which the locking element slides or can be forcibly pushed over the groove wall into the next locking groove. The axial distance between the clamping and sliding stops, together with the groove width, determines the return stroke of the clamping piston.

In a further embodiment, the two axial extensions can be formed as webs extending in the axial direction and can form the sliding stop at the end facing the receptacle. The sliding stop can for example be formed in such a way that the two axial extensions are each shaped in the form of a T-piece. The two radial extensions of the locking element can thus be brought into contact with the slide stop when the tensioning piston is extended, the slide stop being formed by the hook-shaped extensions of the T-piece.

In a further refinement, the clamping stop can be formed by molding on one end face of the receptacle. The clamping stop can be arranged inclined in relation to the plane which runs orthogonally to a plane containing the longitudinal axis of the receptacle. The clamping stop plane is thus the plane which essentially contains the line contact area between the clamping stop and the locking element. The clamping stop plane can thus also run orthogonally to the plane containing the longitudinal axis of the receptacle. The clamping stop can be a chamfer which runs along part of the circumference of the opening of the receptacle.

In a further embodiment, the two axial extensions and the locking ring can be arranged in any relation to the receptacle. For example, if exactly two axial extensions are present, an imaginary connecting line between the exactly two axial extensions can run parallel or perpendicular to a plane which corresponds to the plane of the contact surface between the receptacle and the mounting environment.

In a further embodiment, the receptacle comprises a cylindrical cavity, the tensioning piston being guided with the aid of the cylindrical cavity. Alternatively, the receptacle comprises a cylindrical cavity and a sleeve inserted into the cylindrical cavity, the clamping piston being guided with the aid of the sleeve. Particular cost advantages result when the clamping piston is guided directly in a cylindrical cavity of the receptacle. The receptacle can, for example, be designed as a housing made of aluminum and have the cylindrical cavity for guiding the tensioning piston. Alternatively, the cylindrical cavity can receive a sleeve, for example made of steel; in this case the sleeve that Check valve and other components can be used pre-assembled.

The latching element can for example be designed to be elastically stretchable as a wire; the radius of the annular sections can thus be increased if the locking element is pushed over one of the groove walls. However, the latching element can also have a bending area in the area of one of the two radial extensions, as a result of which the latching element expands in the manner of a clamp.

One of the two axial extensions is arranged in the radial direction between the tensioning piston and one of the two radial extensions of the locking element. One of the two radial extensions is designed to be open, so that the axial extension is not necessarily enclosed. With a total of two radial extensions and two axial extensions, precisely one of the two axial extensions is thus arranged in the radial direction between the tensioning piston and one of the two radial extensions. The design advantageously facilitates the assembly of the locking element.

In a preferred embodiment, the minimum distance between the first or second slide stop assigned to the axial extension - provided to form a transport lock - and the tensioning piston is less than a distance between the axial extension provided for forming a transport lock and the tensioning piston in an axial area between the clamping stop plane and slide stop plane. The transport securing wire can be supported against an area of the sliding stop and thus fix the tensioning piston in its position. At the same time, the surface of the slide stop is enlarged, which also creates advantages with regard to the interaction and wear behavior of the locking element and slide stop.

In a preferred embodiment, the tensioning piston is designed as a hollow cylinder and has a piston head intended to rest on a tensioning rail, the transport securing groove being arranged adjacent to the piston head and being adapted to the geometry of the transport securing wire. The transport locking groove can be the groove closest to the piston head. The locking grooves no longer have to be adapted to the minimum requirements for the geometry of the transport securing wire. It is thus possible to implement locking grooves with flat slopes, small distances, etc., which would not be suitable for a transport lock known from the prior art to reliably fix the tensioning piston on the transport lock wire.

In an advantageous embodiment, the open radial widening has a constriction and an interruption of the locking element, a first end and a second end of the locking element enclosing the interruption and the circumferential distance between the first end and the second end being greater than between partial areas of the latching element that form the constriction. The assembly of the latching element can thus be facilitated in an advantageous manner because the latching element can be plugged onto the piston at the appropriate position.

In an advantageous embodiment, the locking element can be brought into contact with the slide stop in the area of the constriction. In the area of the interruption of the latching element, two end sections of the latching element face each other, partial sections of the two end sections being spaced from one another in the circumferential direction, extending radially outward and being able to be brought into contact with the sliding stop. In spite of the interruption of the locking element, contact with the slide stop can be ensured. Further radial extensions of the latching element that have no interruption can be designed accordingly.

In an advantageous further development, the area of the constriction can be followed by an area of expansion. The expansion can be designed in a V-shape. The design with an expansion advantageously facilitates the assembly of the locking element.

In an advantageous embodiment, the two axial extensions are arranged separately from one another in the area of the sliding stop plane. There is therefore only a connection via the housing in the area of the clamping stop level. In an advantageous manner, the weight of the device can thus be optimized and the feasibility of casting can be improved.

In an advantageous embodiment, the closed radial extension of the locking element is assigned to a first sliding stop and the open radial extension of the locking element is assigned to a second sliding stop, the first sliding stop or the second sliding stop in the area of the sliding stop plane having a ramp-shaped course that allows the locking element to expand follows. The ramp-shaped profile advantageously enables the latching element to be pressed onto an adjacent groove of the tensioning piston not only in the sliding stop plane, but rather along an axial section between the clamping stop and sliding stop. In the contact area between the locking element and slide stop or the Ramp-shaped course of the axial extension can thus be reduced in an advantageous manner, the point loading. Alternatively, the first and the second slide stop can have a ramp-shaped profile in the region of the slide stop plane, which follows the spreading movement of the locking element.

In a particularly advantageous embodiment, the flattened cross section is arranged at the open end of the latching element and the ramp-shaped profile is arranged on the axial extension that is assigned to the closed radial extension. The resistance of the locking element and the resistance of the axial extension can be improved with little effort.

In an advantageous embodiment, the locking element has a flattened cross section on its open radial extension, on its closed radial extension or on the open and closed radial extension, wherein the locking element can be brought into contact with the sliding stop in the area of the flattened cross section.

The flattened cross-section leads to an enlargement of the contact area between the locking element and the sliding stop, whereby the surface pressure can be reduced. Thus, among other things, wear can advantageously be reduced and the material thickness of the locking element can generally be reduced. The flat area resulting from the flattened cross section is thus arranged on the side of the latching element which faces the sliding stop. An additional flattening can be arranged on the opposite side (mirror-symmetrical) in order to simplify assembly and to prevent incorrect assembly. The flattening can be produced, for example, by means of rolling, rolling or embossing.

In an advantageous embodiment, two of the two axial extensions in the circumferential direction enclose a latching section, wherein one of the two annular sections in the area of this latching section can be brought into engagement with one of the latching grooves; In the area of the latching sections, the clamping piston is not surrounded by the receptacle, so that the latching grooves are accessible from the outside. The locking element can thus engage in the locking grooves in the circumferential direction between the axial extensions. The functioning of the detent can thus be observed in the assembled state, which makes maintenance of the internal combustion engine easier. In addition, the latching element is an external component of the clamping device; it is therefore accessible from the outside, which simplifies assembly and disassembly of the latching element. In addition, a securing element can forcibly hold one of the two annular sections in engagement with one of the latching grooves in the region of the latching section. In this way, a transport lock can be realized because a displacement of the locking element into an adjacent locking groove is prevented.

In a further development, the locking element has two ring-shaped sections and two radial extensions, the receptacle having exactly two axial extensions which enclose exactly two locking sections. The latching element can accordingly engage with two annular sections in one of the latching grooves, which enables secure clamping. In addition, the geometric complexity of the locking element can be reduced since only two axial extensions are provided; the locking element accordingly has two radial extensions.

In a further advantageous embodiment, the two axial extensions have a taper on both sides in an axial section between the clamping stop plane and the sliding stop plane in the circumferential direction, whereby the sliding stop is formed in the sliding stop plane. The slide stop is therefore where the taper ends. The two axial extensions can therefore be T-shaped, the web of the T extending between the sliding stop plane and the clamping stop plane and the roof of the T forming the sliding stop plane, from which, facing the web, the sliding stop emerges. The roof of the T can be essentially tangential to the circumferential direction. Alternatively, the roof of the T, forming a segment of a circle, can run in the circumferential direction, the first alternative being advantageous with regard to the ability to be produced by casting.

An embodiment which is advantageous with regard to resetting relates to a clamping device which has a reset ramp in the area of the return stroke, i.e. between the sliding stop plane and the clamping stop plane, the reset ramp being a radially inwardly extending elevation of the axial extension of the receptacle. The reset ramp ensures that a blocking element, such as a screwdriver, can be positioned parallel to the slide stop plane. The reset ramp is preferably arranged in the area of the clamping stop and - forming an insertion bevel - can run in the direction of the sliding stop. The reset ramp is preferably provided on one of the at least two axial extensions, which is surrounded by a radial extension without interrupting the latching element.

As an alternative to a design with a reset ramp, a wedge-shaped special tool can also be used Use that - after positioning - is pressed with one of its edges against the receptacle; In this way, the locking element can be positioned in a comparable manner parallel to the sliding stop plane and fixed in the area of the sliding stop.

A design of the latching element in accordance with one of the embodiments described above advantageously facilitates the assembly of the latching element. In a first step, the locking element can be pushed in an axial region between the clamping stop plane and the sliding stop plane in the radial direction over the first of the two axial extensions. Then the locking element is pushed over the tensioning piston and the second of the two axial extensions. The assembly can thus take place with a preassembled clamping piston with low complexity at the same time.

Resetting the tensioning piston facilitates disassembly and subsequent assembly, for example of a component of an internal combustion engine. As an alternative method, an embodiment with a latching element that has actuation sections in the area of the interruption comes into consideration. Pressing the actuating sections together enables the latching element to be expanded, thereby avoiding a form fit between the latching groove, latching element and clamping stop.

• 1 zeigt einen Kettentrieb für einen Verbrennungsmotor mit seinen wesentlichen Komponenten;
• 2a zeigt ein Ausführungsbeispiel einer hydraulischen Spannvorrichtung;
• 2b zeigt einen rampenförmigen Verlauf des Gleitanschlags der hydraulischen Spannvorrichtung aus 2a;
• 3 zeigt einen Längsschnitt der hydraulischen Spannvorrichtung aus 2a;
• 4 zeigt einen zweiten Längsschnitt der hydraulischen Spannvorrichtung aus 2a;
• 5 zeigt eine Draufsicht der hydraulischen Spannvorrichtung aus 2a;
• 6 zeigt ein Rastelement der hydraulischen Spannvorrichtung aus 2a;
• 7 zeigt ein Rastelement mit einem Beispiel eines abgeflachten Querschnitts der hydraulischen Spannvorrichtung aus 2a;
• 8 zeigt einen Spannkolben der hydraulischen Spannvorrichtung aus 2a;
• 9 zeigt die hydraulische Spannvorrichtung aus 2a mit einer Rücksetzrampe;
• 10 zeigt die Aufnahme der hydraulischen Spannvorrichtung aus 2a;
• 11a zeigt eine hydraulische Spannvorrichtung mit einem Rücksetzwerkzeug und
• 11b zeigt das Rücksetzwerkzeug aus 11 a.

The invention is explained below using an exemplary embodiment:

• 1 shows a chain drive for an internal combustion engine with its essential components;
• 2a shows an embodiment of a hydraulic tensioning device;
• 2 B shows a ramp-shaped profile of the slide stop of the hydraulic clamping device 2a ;
• 3 shows a longitudinal section of the hydraulic clamping device from 2a ;
• 4th shows a second longitudinal section of the hydraulic clamping device 2a ;
• 5 FIG. 11 shows a top view of the hydraulic clamping device from FIG 2a ;
• 6th shows a locking element of the hydraulic clamping device 2a ;
• 7th FIG. 12 shows a locking element with an example of a flattened cross section of the hydraulic clamping device from FIG 2a ;
• 8th shows a tensioning piston of the hydraulic tensioning device 2a ;
• 9 shows the hydraulic clamping device 2a with a reset ramp;
• 10 shows the mounting of the hydraulic clamping device 2a ;
• 11a shows a hydraulic clamping device with a reset tool and
• 11b shows the reset tool 11 a .

In 1 is a chain drive with a hydraulic tensioning device 1 for an internal combustion engine with its essential components. A chain drive basically comprises a drive sprocket connected to the crankshaft 2 , two output sprockets each connected to a camshaft 3 as well as a timing chain 4th who have favourited the drive sprocket 2 with the output sprockets 3 connects. About the Zugstrum 5 the timing chain 4th a drive torque of the crankshaft is transmitted to the camshafts. On the pulling side 5 becomes the timing chain 4th by means of a guide rail 6th guided.

The timing chain 4th becomes on their empty run 7th excited to be able to guarantee their functionality over the service life. For this purpose the timing chain is used 4th by means of a hydraulic clamping device 1 and a tension arm 8th applied with a clamping force. Hydraulic clamping devices 1 according to the embodiment described also ensure a damping of the chain drive.

In 2a is a hydraulic clamping device 1 of a chain drive shown with a transport safety wire 20th secured clamping piston 9 , which is in a cylindrical cavity of a receptacle 10 is guided and locking grooves on its outer peripheral surface 11 having. A latching element is also shown 12 , which has two annular sections 13 (see esp. 6th ) and two radial extensions 14th having, wherein the locking element 12 using the two annular sections 13 with one of the locking grooves 11 is engaged. A clamp stop 15th (please refer 3 ) and a slide stop 16 are arranged axially spaced from one another, in the axial direction between a clamping stop plane 32 and a slide stop plane 33 (please refer 4th ) two axial extensions 17th extend. The two axial extensions 17th point in an axial section between the clamping stop plane 32 and the slide stop plane 33 a taper on both sides in the circumferential direction 18th on, whereby in the sliding stop plane 33 the slide stop 16 is formed. The two axial extensions 17th close a latching section in the circumferential direction 42 one, the two annular sections 13 in the area of the locking section 42 with one of the locking grooves 11 can be engaged.

The two axial extensions 17th and the tensioning piston 9 close the two radial extensions 14th of the locking element 12 not a. The latching element is thus - viewed in the radial direction - not between the tensioning piston 9 and the axial extension 17th arranged. The closed radial extension 14b on the other hand closes - seen in the radial direction - together with the tensioning piston 9 the axial extension 17b on.

In 2 B is an axial extension 17th shown in plan view. In the area of the slide stop 16a is the ramp-shaped course 51 of the slide stop 16a clarified. That on the tension piston 9 sitting down along the taper 18th locking element moving in the axial direction 12 comes in the area of the closed radial expansion 14b on the ramp-shaped course 51 to the plant, whereby the locking element 12 is spread. The ramp-shaped course 51 thus supports an expansion of the locking element 12 , thereby sliding into a next locking groove 11 of the tensioning piston 9 is facilitated. The ramp-shaped course can be on either of the two axial extensions 17a , 17b be arranged or on both axial extensions.

3 shows a longitudinal section through the hydraulic clamping device 1 . The picture is shown 10 with the cylindrical cavity 21st in which the tensioning piston 9 is led. Clamping piston 9 and inner circumferential surface of the cylindrical cavity 21st close a high pressure chamber 22nd one that has an inlet pipe 23 and a check valve 24 that has a valve seat 25th and a spherical closing body 26th has, is supplied with hydraulic medium. In the high pressure room 22nd is an element to reduce the filling volume 27 arranged, the end a vent opening 28 covered. Alternatively, however, a pressure relief valve - not shown - can also be installed in the tensioning piston 9 be used. The tension piston 9 is by means of a spring 29 in the extension direction and thus against the tensioning rail after assembly 8th biased.

The tension piston 9 has locking grooves on the outer circumference 11 on, the locking element 12 into the outermost locking groove 30th intervenes. The locking grooves 11 are arranged circumferentially along the outer circumference and designed in such a way that the tensioning piston is extended 9 enables retraction of the clamping piston 9 However, what is prevented: The locking grooves 11 each have two groove walls that use the locking element 12 on the one hand with the clamping stop 15th and on the other hand with the slide stop 16 can be brought into contact. The groove wall that, when retracted with the clamping stop 15th can be brought into contact, runs steeper than the opposite groove wall, which can be brought into contact with the sliding stop. Excessive retraction is effectively prevented in this way because the locking element 12 form-fitting between locking groove 30th and clamping stop 15th is applied. When the tensioning piston is extended 9 can the locking element 12 with the slide stop 16 are brought into contact, whereby the locking element 12 over the groove wall into the next locking groove 30th slides or can be forcibly pushed.

The axial extensions 17th that make up the slide stop 16 are in 4th shown. The locking element 12 is in engagement with the outermost locking groove 30th and is located in an axial section between the clamping stop plane 32 and the slide stop plane 33 . The axial distance between the clamping stop plane 32 and the slide stop plane 33 determines the return stroke 34 of the tensioning piston 9 . An inlet bore is also shown 31 showing the high pressure room 22nd via the check valve 24 supplied with hydraulic fluid.

On one of the two axial extensions 17th is a first sliding stop 16a educated. An area pulled radially towards the piston 52 of the first slide stop 16a forms with a transport locking groove 54 of the tensioning piston 9 and with the axial extension 17th a receptacle for a transport safety wire 20th . Also on the opposite axial extension 17th that of the open radial extension of the locking element 14a is assigned, is the second slide stop 16b towards the clamping piston 9 drawn. In this way, the contact surface between the locking element 12 and slide stop 16b enlarge.

A top view of the hydraulic tensioner 1 is in 5 shown. The tension piston 9 is in the cylindrical cavity of the housing designed as a housing 10 used, the locking element 12 on the tension piston 9 sits. The locking element 12 comprises two annular sections 13 that are in a locking groove 11 of the tensioning piston 9 intervention. A first radial expansion 14a of the locking element 12 closes with the clamping piston 9 the first axial extension 17a on. A second radial extension 14b closes with the clamping piston 9 the second axial extension 17b on. The second radial extension 14b shows a constriction 45 and an interruption 35 of the locking element 12 on. To the area of the constriction 45 closes an area of expansion 46 at. The expansion 46 can be designed V-shaped. The design with an expansion 46 advantageously facilitates the assembly of the latching element 12 .

The further design of the locking ring 12 with constriction 45 and widening 46 illustrated 6th . In the area of interruption 35 of the locking element 12 face a first end 43 and a second end 44 of the locking element 12 opposite, with the first end 43 and the second end 44 of the locking element 12 the interruption 35 lock in. At least in a non-pretensioned state of the locking element 12 is the circumferential distance between the first end 43 and the second end 44 larger than between subregions of the latching element that form the constriction 45 form. The geometric design makes it easier for the latching element to be pushed on 12 in the radial direction.

The moreover one is both at the open end 14a as well as at the closed end 14b the radial expansion 14th a flattened cross-section 50 arranged. In the area of the flattening of the flattened cross-section 50 is the locking element 12 contactable with the sliding stop, whereby the contact surface - compared to a circular cross-section - is enlarged.

The 7th illustrates alternative embodiments of a reduction in cross section 50 . The flattening can be on one side or on both sides of the locking element 12 be arranged. In addition, the flattening can either only occur on the closed radial extension 14b or only at the open radial extension 14a or at both radial extensions 14a , 14b be arranged.

The 8th illustrates a tension piston 9 the hydraulic clamping device of the 2a . The tensioning piston has on the outer circumference 9 Locking grooves 11 on. A piston head 56 is to be placed on a tensioning rail 8th (please refer 1 ) intended. A transport locking groove 54 is the piston head 56 arranged adjacent and the geometry of the transport securing wire 20th (please refer 4th ) customized.

9 shows the hydraulic clamping device 1 out 2a with an alternatively provided reset ramp 47 . The picture is shown 10 with the cylindrical cavity 21st , at the opening of which the clamping stop 15th is formed. The axial extension 17th extends in the axial direction from the receptacle 10 away and ends with the slide stop 16 . The axial position of the clamping stop plane 32 and the slide stop plane 33 have a significant influence on the maximum possible return stroke 34 a (not shown) tensioning piston before the locking element in an adjacent locking groove 11 is convicted. In the area of the return stroke 34 is the reset ramp 47 arranged. The reset ramp 47 is a radially inwardly extending elevation of the web 48 the T-shaped axial extension 17th . The T-shaped axial extension 17th closes with a roof 49 from.

In a first step, a blocking element (not shown), such as a screwdriver, can thus be positioned in an axial area between the clamping stop plane 32 and the slide stop plane 33 in a tangential direction to the cylindrical cavity 21st (or in the tangential direction to a clamping piston, not shown) are introduced in such a way that the blocking element after insertion between a locking element (not shown) (see for example 1 to 7th , Reference numbers 12 ) and the clamping stop 15th is arranged. The reset ramp is therefore on one of the at least two axial extensions 17th provided by a radial extension 14th without interruption 35 of the locking element 12 is surrounded (see for example 5 , axial extension 17a ). The reset ramp 47 ensures that the blocking element is parallel to the sliding stop plane 33 is positioned. In addition, the locking element 12 between blocking element and sliding stop 16 be set in the axial direction. In a second step, the extended tensioning piston (not shown) 9 towards recording 10 relocated and then fixed with a transport safety wire.

In 10 is the recording 10 the hydraulic clamping device 2a shown. It can be seen that the axial extension is at any point on an end face of the receptacle 10 is malleable. The axial extension 17th comprises an axially extending web 48 and a roof 49 , whereby the clamping stop level 32 and the slide stop plane 33 as well as the slide stop 16 are formed. The roof 49 is in the area of the slide stop 16 inwards towards the clamping piston or the opposite sliding stop 16 drawn. As a result, on the one hand, the contact surface between a locking element 12 and the slide stop 16 be enlarged. On the other hand, the receptacle for a transport safety wire 20th are formed. These contours as well as the reset ramp 47 and the clamp stop 15th can be manufactured by casting without the need for post-processing.

In 11a is illustrated how the tensioning piston 9 using a reset tool 58 can be shifted from the extended state to the retracted state. The reset tool 58 is between clamping piston 9 and axial extension 17th pushed, with the locking element 12 between the reset tool 58 and the slide stop 16 is located. This prevents the locking element 12 in contact with the clamping stop 15th and the retraction of the clamping piston 9 blocked. The tension piston 9 so can in the recording 10 be relocated. When the locking element is in the piston head 57 seen from the first locking groove 11 the reset tool 58 removed and - after moving the tensioning piston further 9 in the recording 10 - a transport safety wire 20th into the transport locking groove 54 be pushed.

In 11b is the reset tool 58 shown. The reset tool 58 is designed flat and the distance between the clamping piston 9 and the axial extension 17th customized. The reset tool points in the longitudinal direction 58 a wedge-shaped profile.

List of reference symbols

1

hydraulic clamping device

2

Drive sprocket

3

Output sprocket

4th

Timing chain

5

Traction

6th

Guide rail

7th

Empty run

8th

Tension arm

9

Clamping piston

10

admission

11

Locking groove

12

Locking element

13

annular section

14th

radial extension

14a

open radial extension

14b

closed radial extension

15th

Clamping stop

16

Sliding stop

16a

first slide stop

16b

second slide stop

17th

axial extension

17a

first axial extension

17b

second axial extension

18th

rejuvenation

20th

Transport safety wire

21st

cylindrical cavity

22nd

High pressure room

23

Feed line

24

check valve

25th

Valve seat

26th

spherical closing body

27

Element for reducing the filling volume

28

Vent

29

feather

30th

outermost locking groove

31

Inlet bore

32

Clamp stop level

33

Sliding stop plane

34

Return stroke

35

Interruption

38

-

42

Locking section

43

first end

44

second end

45

Constriction

46

Widening

47

Reset ramp

48

web

49

top, roof

50

flattened cross-section

51

ramp-shaped course

52

Area pulled radially towards the piston

53

Area pulled radially towards the piston

54

Transport locking groove

55

Clamping piston axis

56

Plane of symmetry

57

Piston head

58

Reset tool

Claims (9)

Hydraulic tensioning device (1) for a chain drive with a tensioning piston (9) which is guided in a receptacle (10) and which has locking grooves (11) on its outer circumferential surface, and with a locking element (12) which has two annular sections (13) and which has an open and a closed radial extension (14a, 14b), wherein the locking element (12) can be brought into engagement with one of the locking grooves (11) with the aid of the two annular sections (13), as well as with a clamping stop (15) , a first sliding stop (16a) and a second sliding stop (16b), wherein the clamping stop (15) and the sliding stops (16a, 16b) are axially spaced from each other and form a clamping stop plane (32) and a sliding stop plane (33) and wherein the receptacle (10) has two axial extensions (17) which extend in the axial direction between the clamping stop plane (32) and the sliding stop plane (33), characterized in that one of the two axial extensions (17), the first or second sliding stop (16a, 16b) assigned to this axial extension intended to form a transport lock and a transport securing groove (54) in the tensioning piston (9) forms a receptacle for a transport securing wire (20). Hydraulic clamping device according to Claim 1 , characterized in that the distance between the first or second sliding stop (16a, 16b) assigned to the axial extension provided for the formation of a transport lock and the tensioning piston (9) is smaller than the distance between the axial extension provided for forming a transport lock and the tensioning piston in an axial area between the clamping stop plane and the sliding stop plane. Hydraulic clamping device according to Claim 1 or 2 , characterized in that the tensioning piston (9) is designed as a hollow cylinder and has a piston head (57) intended to rest on a tensioning rail, the transport securing groove (54) being arranged adjacent to the piston head (57) and being adapted to the geometry of the transport securing wire (20) . Hydraulic clamping device according to one of the preceding claims, characterized in that the open radial widening (14a) has a constriction (45) and an interruption (35) of the locking element (12), a first end (43) and a second end (44 ) of the locking element (12) enclose the interruption (35) and wherein in the circumferential direction the distance between the first end (43) and the second end (44) is greater than between subregions of the locking element (12) which form the constriction (45) . Hydraulic clamping device according to one of the preceding claims, characterized in that the two axial extensions (17) are arranged separately from one another in the region of the sliding stop plane (33). Hydraulic clamping device according to one of the preceding claims, characterized in that the closed radial extension (14b) of the locking element (12) is assigned to a first sliding stop (16a) and the open radial extension (14a) of the locking element is assigned to a second sliding stop (16b) wherein the first slide stop (16a) or the second slide stop (16b) has a ramp-shaped profile (51) in the region of the slide stop plane (33), which follows a spreading movement of the locking element (12). Hydraulic clamping device according to one of the preceding claims, characterized in that the locking element (12) has a flattened surface on its open radial extension (14a), on its closed radial extension (14b) or on the open and closed radial extension (14a, 14b) Has cross section (50), wherein the locking element (12) can be brought into contact with the sliding stop (16) in the region of the flattened cross section (50). Hydraulic clamping device according to one of the preceding claims, characterized in that the two axial extensions (17) enclose a latching section (42) in the circumferential direction, one of the two annular sections (13) having one of the latching grooves (11) in the area of the latching section (42) ) can be engaged. Hydraulic clamping device according to one of the preceding claims, characterized in that the two axial extensions (17) in an axial section between the clamping stop plane (32) and the sliding stop plane (33) in the circumferential direction have a taper (18) on both sides, whereby in the sliding stop plane ( 33) the slide stop (16) is formed.

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