Working cylinder

Abstract

The invention relates to a working cylinder, in which the cylinder has a coupling section with a coupling ring and a locking body for coupling a closure part to a cylinder tube end section, the cylinder tube has a circumferential inner annular groove at the end section of the cylinder tube and the closure part is axially pushed into the end section of the cylinder tube and has an axially distal outer annular groove which is open on one side, the inner annular groove and the outer annular groove forming an annular groove space in which a coupling ring is arranged and which is radially surrounded by the inner annular groove, the coupling ring is formed by a plurality of coupling ring segments in a segmented manner by means of the separating cutouts, the coupling ring segments are arranged abutting against each other at the separating cutouts, and the separating cutouts of the at least one piston ring segment are formed parallel to each other or open in the concentric direction, the closure part is axially fixed in a one-sided form-fitting manner in the distal direction by the coupling ring, and wherein the locking body is arranged axially distally on the closure part and has a circumferential annular surface which forms a pressure contact with the coupling ring and fixes the coupling ring in the annular groove space in a form-fitting manner, the locking body axially fixes the closure part in a form-fitting manner on one side in the proximal direction by means of pressure contact with the coupling ring.

Description

Technical Field

[0001] The invention relates to a working cylinder, in particular to a hydraulic working cylinder. Background Art

[0002] Such working cylinders are known from the prior art. They usually have a cylinder tube and a closure part connected thereto.

[0003] The detachable connection of the closing part and the cylinder tube for producing such a working cylinder is generally achieved by screwing the closing part and the cylinder tube together according to the prior art. These working cylinders are therefore also referred to as screw cylinders in the prior art.

[0004] Furthermore, it is known, for example, from the prior art to connect the bottom closure part to the cylinder tube by MAG welding and then merely to screw the closure part in place.

[0005] According to the prior art, both screw-on cylinders and cylinders on which only one closure part is screwed on and the other closure part is MAG-welded are available with relatively high quality and have proven to be high-quality and reliable products.

[0006] A production disadvantage identified here is that it is difficult to coordinate the threads of the closure part and the cylinder tube to one another so that a suitable tightening torque is applied during screwing in the case of a desired specific angular position of the closure parts relative to one another or to the cylinder tube.

[0007] For example, EP 2 898 224 B1 has already disclosed a solution to overcome this problem. It is a hybrid connection that cooperates with a positive connection by means of an elastic coupling ring and a non-positive connection by means of an interference fit. Here too, it is a high-quality solution for a releasable and at the same time highly loadable connection, but special devices are required for assembly and disassembly. Summary of the invention

[0008] The object of the present invention is to provide a working cylinder which has a high degree of reliability, can be produced at low cost and is dismantled.

[0009] This object is achieved with regard to the working cylinder by the features listed in patent claim 1. Preferred developments are revealed in the dependent claims.

[0010] According to the invention, the working cylinder has a cylinder and piston unit as an essential component and is characterized in particular by a specially designed coupling section.

[0011] The cylinder of the working cylinder according to the invention comprises a cylinder tube, a closing part and a further closing part.

[0012] As is known in working cylinders, a cylinder tube with a cylinder tube end section and a further cylinder tube end section has two opposite cylinder tube end sections. A closing component is arranged at the cylinder tube end section and a further closing component is arranged at the further cylinder tube end section. The cylinder tube end section and the further cylinder tube end section are also generally referred to as cylinder tube end sections below. In a corresponding manner, the closing component and the further closing component are also generally referred to as closing components.

[0013] The cylinder tube and the closure component arranged thereon form the cylinder inner chamber. In the cylinder inner chamber, the piston unit forms at least one working chamber. Preferably, the piston unit is configured as an assembly consisting of a piston and a piston rod, wherein the piston rod slides through one of the closure components, which then serves as a guide closure component. However, the piston unit can also exist, for example, as a plunger piston or as a piston unit of a synchronous cylinder.

[0014] The working cylinder according to the invention is further characterized by a coupling section which is designed in a special manner.

[0015] The coupling section according to the invention comprises a closure part, a cylinder tube end section, a segmented coupling ring and a locking body.

[0016] The elements of the coupling section and their interaction will be described later.

[0017] The closing element is arranged so as to be pushed axially into the end section of the cylinder tube. Here, the closing element has a cylindrical outer side surface, also referred to as the closing element outer side surface, and the cylinder tube has a cylindrical inner side surface, also referred to as the cylinder tube inner side surface. The closing element is therefore radially surrounded by the inner side surface. The two side surfaces correspond in their diameters, whereby the closing element is defined in its positional relationship relative to the cylinder tube, in addition to the axial positional relationship (i.e., in addition to the linear freedom along the longitudinal axis of the cylinder). Optionally, an auxiliary interference fit may also be present.

[0018] At the cylinder tube end section, the cylinder tube has a circumferential inner annular groove on the inner side. Its contour corresponds to the cross section of the coupling ring and is preferably approximately semicircular in the case of a circular coupling ring cross section.

[0019] At the same time, the closure part has an outer annular groove on its outer side which is open on one side in the axial distal direction. The axial distal direction is understood to be the direction pointing away from the axial cylinder center. Here too, the contour corresponds to the cross section of the coupling ring and is preferably constructed approximately in a quarter circle in the case of a circular coupling ring cross section.

[0020] The inner annular groove and the outer annular groove form an annular groove space in which a coupling ring is arranged. Here, the coupling ring is radially surrounded by the outer annular groove. Since the outer annular groove is axially open on one side at the closure component, the annular groove space opened by the two annular grooves is not completely surrounded by the annular grooves, but is accessible axially from the far side.

[0021] According to the invention, the coupling ring is segmented by means of separating cuts. It is composed of a plurality of coupling ring segments, also referred to as ring segments below.

[0022] The ring segments are arranged so as to abut against each other at the separating cutouts. It is important for the invention that the ring segments abut against each other practically without gaps due to the abutting arrangement. Here, the opposing faces of the separating cutouts at the abutting are approximately parallel to each other. It is also important for the invention that all the ring segments together form a practically gapless annular body and span an angle of 360 degrees.

[0023] As a special advantage compared to elastic piston rings with piston ring gaps, a continuous annular surface or annular line is provided for the transmission of forces between the groove wall of the inner annular groove and the coupling ring on the one hand and between the coupling ring and the groove wall of the outer annular groove on the other hand.

[0024] According to the invention, the separating cuts of at least one piston ring segment are constructed parallel to each other or open in the concentric direction. Thus, surprisingly, a solution has been found to arrange the coupling ring in the outer annular groove in the eccentric engagement direction practically without gaps, which is not possible in the case of radial separating cuts. Parallel construction is understood to mean that the separating cuts at one end of the ring segment and at the other end of the ring segment have surfaces that are parallel to each other. Concentric construction is understood to mean that the separating cuts at one end of the ring segment and at the other end of the ring segment have surfaces that are parallel to each other, whose planes are on the one hand approximately parallel to the longitudinal axis of the cylinder and on the other hand are at an angle that makes it possible to push the relevant ring segment in the radial eccentric direction.

[0025] In the interaction of the outer annular groove and the inner annular groove, the closure element is fixed axially on one side in a positively locking manner in the distal direction by the coupling ring. In this direction, the full load resulting from the operating pressure is absorbed. Advantageously, annular surface sections of the inner annular groove and the outer annular groove that are adapted to the coupling ring are available here, so that undesirably high surface pressures are avoided by a sufficiently large surface.

[0026] Furthermore, the locking body is arranged axially distally at the closure part by means of a releasable fixing. An axially distal arrangement is understood to mean that the locking body is arranged opposite to the axially distal single-sided opening of the outer annular groove. Releasable fixing is particularly understood to mean the screwing of the locking body at the closure part. When the closure part is a guided closure part, the locking body can be configured in particular as an annular body, thereby leaving free space for the piston rod. In the case of a bottom closure part, the locking body can also be configured as a flat cylinder. Furthermore, the locking body can also exist in multiple pieces.

[0027] The locking body has a surrounding annular surface, which is configured to be in pressure contact with the coupling ring and to lock the coupling ring in the annular groove space. The contour of the annular surface can preferably correspond to the cross section of the coupling ring and be configured, for example, approximately in a quarter circle. Therefore, the locking body can cover the remaining open section of the annular groove space. However, other contours, such as a partially circular contour less than 90 degrees, an inclined annular surface without curvature, or a partially circular contour with a radius different from the cross section of the coupling ring are equally possible, so as to optimize, for example, the pressure contact and thus optimize the position fixation of the coupling ring.

[0028] The locking body fixes the closure part axially on one side in a positive locking manner in the proximal direction by means of pressure contact with the coupling ring. The load transfer here is achieved indirectly and simultaneously via the releasable fixing, which is advantageously not a problem since only small forces have to be absorbed in this direction, for example from the friction of the piston unit in the guide closure part.

[0029] After the axial distal position has been fixed by the cooperation of the outer annular groove, the coupling ring and the inner annular groove, the positional relationship relative to the cylinder tube in the remaining axial opposite direction is also provided by means of the locking body. As a result, the closure part and the cylinder tube are now completely connected in a positive locking manner.

[0030] The solution according to the invention has the following advantages in particular.

[0031] The continuous annular surface or annular line for transmitting force between the groove wall of the inner annular groove and the coupling ring on the one hand and between the coupling ring and the groove wall of the outer annular groove on the other hand avoids uneven stresses in the groove region of the coupling partner, reduces, for example, notch stresses and thus increases the maximum load capacity.

[0032] Furthermore, a possible higher load capacity is advantageous, since the coupling ring does not have to be of elastic design due to its segments and can have a larger cross section.

[0033] In addition, the particularly easy releasability of the connection is advantageous. In the case of the corresponding embodiment, it is therefore possible to disassemble the locking body, remove the annular segment and thus remove the closure part for inspection or maintenance purposes by means of a screwdriver or a wrench with a standard driver.

[0034] In this respect, there is also the advantage of simple assembly, because before the locking body is inserted, the ring segment is already fixed radially outwardly by the outer annular groove and radially inwardly by the closure element. In addition, the relatively low susceptibility to assembly errors is advantageous, because the locking body cannot be inserted if the ring segment is not placed correctly.

[0035] Furthermore, the structural simplicity of this solution is particularly advantageous, since not only the cylinder tube, the closing element but also the locking body can be produced by means of conventional turning and milling processes.

[0036] According to a first advantageous development, the working cylinder is characterized in that the piston ring has four piston ring segments and in that all separating cuts are designed parallel to one another.

[0037] According to this improved solution, there are two similar annular segments of the first type and two similar annular segments of the second type. Here, the annular segments of the same type are arranged opposite each other. After the two annular segments of the first type are positioned in the inner annular groove, the two annular segments of the second type can be inserted from the middle in a radial eccentric direction due to the parallel separation cuts. Thus, the four annular segments can be connected by means of the coupling ring to form a practically gapless annular body that is completely closed over 360 degrees.

[0038] According to a further advantageous development, the working cylinder is characterized in that the locking body is arranged with axial elastic prestressing in the proximal direction.

[0039] In particular in the case of hydraulic working cylinders, the connection between the cylinder tube and the closure element is subject to high mechanical stresses due to the high and changing operating pressures and the dynamic loads associated therewith. In the case of a positive connection, this can lead to the occurrence of undesirable play, which is also referred to as so-called breathing. Such play can occur when the groove walls of the annular groove and the coupling ring are molded to one another.

[0040] The elastic prestress of the locking body is used to realize a permanent force loading relative to the coupling ring at the annular surface of the locking body. If the coupling ring and the groove wall are adapted to each other, the coupling ring is pressed deeper into the annular groove by this force, thereby maintaining no gap.

[0041] According to an advantageous improvement scheme based on this, the working cylinder is characterized in that the releasable fixing of the locking body is constructed by means of a head screw, whose corresponding screw head has a one-sided support portion on the locking body and an axial force is applied at the support portion, and the head screw has an elastic bending relative to its longitudinal axis.

[0042] According to this refinement, it is provided that the screw head rests only partially, preferably approximately halfway, on the locking body. When the screw head is tightened with a tightening torque, the screw head is loaded eccentrically, whereby the screw bends at the free shank end in the direction of the unsupported side of the screw head. According to this refinement, this bending is within the limits of elastic deformation, whereby the screw advantageously, on the one hand, acts like a spring element to cause axial elastic prestressing of the locking body in the proximal direction and at the same time secures it against screwing out.

[0043] With this structurally simple improvement, surprisingly, a solution has been found which is resistant to breathing and achieves a particularly durable and reliable connection.

[0044] According to a further advantageous development based thereon, the working cylinder is characterized in that the circumferential annular surface of the locking body is designed as a cone.

[0045] According to the invention, the surrounding annular surface is in pressure contact with the coupling ring. In cooperation with the axial elastic prestressing of the locking body in the proximal direction, the force is effectively divided at the coupling ring by means of the annular surface inclined as a cone into an axial and radial portion, wherein the axial portion presses the piston ring, in particular, into the outer annular groove of the closure part, while the radial portion presses the piston ring, in particular, into the inner annular groove of the cylinder and thus counteracts the formation of gaps and breathing.

[0046] According to another development, the working cylinder is characterized in that a coupling section according to the invention is arranged at each of the two cylinder tube end sections. The two coupling sections have the same basic structure, so that the description of the coupling section applies in a corresponding manner to the other coupling section at the opposite end of the cylinder tube. Advantageously, a solution is thus described in which access is made possible at both ends of the working cylinder for inspection or maintenance purposes. It is also advantageously possible for the cylinder tube to be constructed identically at both ends, thereby simplifying production. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention is further explained as an embodiment with the following (without the illustration of the piston unit):

[0048] Figure 1 Cross-section view showing the joint segment

[0049] Figure 2 An enlarged section showing the coupling section (illustration without coupling ring)

[0050] Figure 3 An enlarged section showing a coupling section (with illustration of coupling ring and axial prestressing force)

[0051] Figure 4 Cross-sectional view showing the working cylinder (overall view)

[0052] Figure 5 Showing the coupling ring with the separation cutout (top view and cross section)

[0053] Figure 6 Showing a coupling ring with parallel separation cuts (schematic illustration)

[0054] Figure 7 Showing the coupling ring with the separation cutout opened (schematic illustration)

[0055] Figure 8 An axial view of the coupling segment is shown.

[0056] Here, the same reference numerals in different figures denote correspondingly identical features or components. These reference numerals are also used in the description even if they are not shown in the relevant figure. DETAILED DESCRIPTION

[0057] Figure 1 The guide-side section of a working cylinder with a coupling section 7 arranged there on the cylinder 1 in one embodiment is shown. The cylinder 1 has a closure part 4a (here configured as a guide closure part) and a cylinder tube 3. A cylinder tube end section 5a is arranged at the end of the guide side of the cylinder tube 3, which is configured here as a separate sleeve. Alternatively (not shown here), the cylinder tube 3 can also be designed as a whole. The inner chamber 6 is formed by the closure parts 5a, 5b. In addition, the piston rod of the piston unit 2 and at least one working chamber 6.1 (piston rod chamber in this embodiment) formed in this way are shown.

[0058] In addition to the cylinder tube end section 5 a , the coupling section 7 has a coupling ring 8 and a locking body 9 with a detachable fixing 10 .

[0059] Figure 2 The connecting section is shown in an enlarged view, wherein Figure 2 There is an initial illustration without the coupling ring 8 .

[0060] The cylinder tube 3 has an inner annular groove 11.1 at its cylinder tube end section 5a, which is arranged on the inner side of the cylindrical cylinder tube. Corresponding to the circular cross section of the coupling ring 8 in this embodiment, the inner annular groove 11.1 has a roughly semicircular profile. Radially opposite, the closure part 4a has an outer annular groove 11.2 on its cylindrical outer side, which has a roughly quarter-circular profile and is therefore open on one side in the distal axial direction. The two annular grooves 11.1, 11.2 open the annular groove space 11.3. In this embodiment, the locking body 9 is annularly constructed and axially placed so that the surrounding annular surface 9.1 covers the quarter of the annular groove space that is still open by the two annular grooves 11.1 and 11.2. In addition, the axial direction description (distal and proximal) is shown by arrows.

[0061] Figure 3 Roughly Figure 2 3 and the cooperation of the releasable fixing with the locking body 9 for generating the axial elastic prestressing.

[0062] The support cone of the head screw designed as a countersunk screw for the releasable fixing 10 is designed asymmetrically, wherein the support section at the closing part 4a is axially deepened relative to the support section at the locking body 9. When the countersunk screw is screwed in, there is therefore a one-sided support 10.1 at the locking body 9. When a tightening torque is applied, the countersunk screw bends due to the one-sided force on the screw head, as shown by the auxiliary lines (dashed lines). The upper section is bent relative to the longitudinal axis and the axial plane of the screw head is inclined. At higher tightening torques, the screw head is now additionally supported at a deeper support area at the closing part. Bending beyond the elastic range is thus prevented and at the same time a fixation is achieved that prevents the countersunk screw from loosening.

[0063] Due to the releasable connection 10 acting as an elastic clamping element, the locking body 9 is elastically prestressed in the axial proximal direction and transmits the force to the coupling ring 8 via the surrounding annular surface 9.1. The surrounding annular surface 9.1 is designed as a cone and therefore has an inclined contour, which as an inclined plane advantageously acts as a force conversion and thus increases the force for pressing the coupling ring into the annular grooves 11.1, 11.2. This advantageously prevents the formation of gaps and the breathing of the working cylinder that can occur due to the high and moreover dynamic operating loads acting axially distally.

[0064] Supplemented by Figure 1 , Figure 4 An overall view is shown, in which a further cylinder tube end section 5b and a further closure element 4b, which is present as a bottom closure element, are also shown. Figure 4 In the exemplary embodiment shown in FIG. 4 , however, there is no connection according to the invention between the further cylinder tube end section 5 b and the further closure part 4 b , but rather a laser welded connection.

[0065] exist Figure 5 , a four-part embodiment variant of the coupling ring 8 is shown. Here, all the separating cuts 8.1 are oriented in parallel. Four coupling ring segments 8.2 are formed by four separating cuts 8.1.

[0066] Supplemented by Figure 5 , Figure 6An embodiment with parallel separation cuts 8.1 is shown in a schematic diagram form. Accordingly, there are two coupling ring segments 8.2 of the same form. First, two coupling ring segments of the first form (shown on the left and right) can be positioned in the inner annular groove 11.1. Then, two coupling ring segments of the second form (shown above and below) can be inserted between the coupling ring segments 8.2 of the first form by means of an eccentric radial engagement movement. The corresponding engagement movement of the coupling ring segments 8.2 of the second form is shown by two arrows. After the engagement, there is a gapless contact of all coupling ring segments 8.2 that butt against each other, thereby providing a practically uninterrupted force transmission between the cylinder tube 3 and the closure component 4a over a range of 360 degrees.

[0067] Figure 7 Roughly Figure 6 so that the description therein applies accordingly. Figure 6 In the embodiment, Figure 7 The separating slots 8 . 1 in the embodiment are however designed in a radially concentrically open angular position.

[0068] In the case of the coupling movement of the second form of the coupling ring segments 8.2, on the one hand, the coupling between the first form of the coupling ring segments 8.2 is facilitated and on the other hand, a pressure contact is established at the separation cutout 8.1 through the wedge-shaped entry, which supports the gap-free positioning of the coupling ring segments 8.2 with respect to each other.

[0069] Figure 8 Finally, an axial view of the cylinder 1 is shown, wherein the piston unit 2 is not shown here. The non-visible coupling ring 8 is indicated by two concentric dashed lines.

[0070] The locking body 9 is here designed as an annular body, which surrounds the passage of the piston rod in this way. The releasable fixing 10 is constructed by three screws arranged at an angle of 120 degrees, whose heads are supported on one side on the locking body and on the axially deeper support of the closure part 4a with a one-sided support 10.1.

[0071] Reference numerals list

[0072] 1 cylinder

[0073] 2 piston units

[0074] 3 cylinder pipe

[0075] 4a Closing parts

[0076] 4b Another closing member

[0077] 5a Cylinder tube end section

[0078] 5b Another cylinder tube end section

[0079] 6 cylinder bore

[0080] 6.1 Working chamber

[0081] 7 Connection section

[0082] 8Connection ring

[0083] 8.1 Separation incision

[0084] 8.2 Connection Ring Segmentation

[0085] 9 Locking body

[0086] 9.1 Surrounding Torus

[0087] 10Releasable fasteners

[0088] 10.1 One-side support

[0089] 11.1 Inner annular groove

[0090] 11.2 External annular groove

[0091] 11.3 Annular groove space

Claims

1. A working cylinder comprising a cylinder (1) and a piston unit (2), in, The cylinder (1) comprises a cylinder tube (3), a closing part (4a) and another closing part (4b). wherein the cylinder tube (3) comprises a cylinder tube end section (5a) and a further cylinder tube end section (5b), wherein the closing component (4a) is arranged at the cylinder tube end section (5a) and the further closing component (4b) is arranged at the further cylinder tube end section (5b), and wherein the cylinder tube (3) and the closing components (4a, 4b) form a cylinder interior (6), The piston unit (2) forms at least one working chamber (6.1) in the cylinder interior (6). The cylinder has a coupling section (7) having the closing component (4a), the cylinder tube end section (5a), a coupling ring (8) and a locking body (9). The cylinder tube (3) has a circumferential inner annular groove (11.1) on the inner side of the cylinder tube at the cylinder tube end section (5a). The closure component (4a) having a cylindrical closure component outer side is axially pushed into the cylinder tube end section (5a) and is radially surrounded by the cylindrical cylinder tube inner side of the cylinder tube end section (5a) at the closure component outer side and has an outer annular groove (11.2) which is open on one side axially distally. The inner annular groove (11.1) and the outer annular groove (11.2) form an annular groove space (11.3), in which the coupling ring (8) is arranged and radially surrounded by the inner annular groove (11.1). The coupling ring (8) is constructed in sections by means of separating cutouts (8.1), and is composed of a plurality of coupling ring sections (8.2). wherein the coupling ring segments (8.2) are arranged to abut one another at the separation cutouts (8.1) and the separation cutouts (8.1) of at least one piston ring segment (8.2) are constructed to open parallel to one another or in a concentric direction, wherein the closure element (4a) is fixed axially and unilaterally in a form-fitting manner in the distal direction by means of the coupling ring (8), The locking body (9) is arranged axially distally on the closure part (4a) by means of a releasable fixing element (10) and has a surrounding annular surface (9.1) which is configured to be in pressure contact with the coupling ring (8) and to fix the coupling ring (8) in the annular groove space in a form-fitting manner. The locking body (9) fixes the closure element (4a) in a unilateral axial and form-fitting manner in the proximal direction by means of a pressure contact with the coupling ring (8).

2. The working cylinder according to claim 1, characterized in that: The coupling ring (8) has four coupling ring segments (8.2) and all separating cutouts (8.1) are designed parallel to one another.

3. A working cylinder according to any one of the preceding claims, characterized in that The locking body (9) is arranged with axial elastic prestressing in the proximal direction.

4. The working cylinder according to claim 3, characterized in that: The releasable fixing part (10) of the locking body (9) is constructed by means of a head screw, the corresponding screw head of which has a one-sided support part (10.1) on the locking body and an axial force is applied at the one-sided support part, and the head screw has an elastic bending relative to its longitudinal axis.

5. The working cylinder according to claim 3 or 4, characterized in that: The circumferential annular surface (9.1) of the locking body (9) is designed as a cone.

6. A working cylinder according to any one of the preceding claims, characterized in that The cylinder (1) has a further coupling section which comprises the further closure component (4b), the further cylinder tube end section (5b), a further coupling ring and a further locking body and is constructed in the same manner as the coupling section (7a).

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