Actuating cylinder, in particular a hydraulic actuating cylinder

Abstract

The present invention relates to an actuating cylinder, the cylinder having a connecting portion with a connecting ring and a locking body for connecting a closure part to a cylinder tube end portion. At the cylinder tube end portion, the cylinder tube has a circumferential inner groove, the closure part is pushed axially into the cylinder tube end portion, and has an outer annular groove opening on one side axially distally. The inner annular groove and the outer annular groove form an annular groove space, the connecting ring is arranged in the annular groove space and is surrounded radially by the inner annular groove. The connecting ring is designed in a segmented form composed of a plurality of connecting ring segments by a separating cut, and the connecting ring segments are arranged to be butt-joined to each other at the separating cut. The separating cuts of at least one piston ring segment are designed to open parallel or coaxial to each other. The closure part is fixed at one axial end in the distal direction in a form-fitting manner by the connecting ring. The locking body is arranged axially distally on the closure part and has a circumferential ring surface that forms a press contact with the connecting ring to fix the connecting ring in a form-fitting manner within the annular groove space. The locking body fixes the closure part at one axial end in the proximal direction in a form-fitting manner by the press contact with the connecting ring.

Description

Technical Field

[0001] The present invention relates to an actuating cylinder, and more particularly to a hydraulic actuating cylinder.

Background Art

[0002] The actuating cylinder itself is known from the prior art. An actuating cylinder typically has a cylinder tube and a closure part connected to the cylinder tube.

[0003] According to the state of the art, a detachable connecting part of the closure part to the cylinder tube for manufacturing such an actuating cylinder is usually formed by screwing the closure part and the cylinder tube. Therefore, in the state of the art, these actuating cylinders are also referred to as screw-type cylinders.

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

[0005] Both the screw-type cylinder and the cylinder in which only one closure part is screwed on top and the other closure part is MAG welded have been found to be of high quality and available according to the prior art and to be excellent and highly reliable products.

[0006] A drawback in manufacturing is that it is difficult to adapt the threads of the closure part and the cylinder tube to each other such that an appropriate tightening torque is applied when screwing the closure part and the cylinder tube together when placing the closure parts relative to each other and the closure parts relative to the cylinder tube in a desired special angular position.

[0007] One solution to overcome this problem is known, for example, from the specification of European Patent No. 2898224 (B1). The specification of European Patent No. 2898224 (B1) describes a hybrid connection that combines a form-fitting connection with a spring-type connecting ring and a force-fitting connection by interference fit. This is also a high-quality solution for a detachable connection that can withstand large loads, but special devices are required for installation and removal.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to provide an operating cylinder that has high reliability, is highly cost-effective in production, and can be removed.

Means for Solving the Problems

[0010] In relation to the operating cylinder, this object is solved by the features listed in claim 1. Another preferred development becomes apparent from the dependent claims.

[0011] According to the present invention, an operating cylinder has, as its basic components, a cylinder and a piston. The operating cylinder is characterized in particular by a specially designed connection section.

[0012] The cylinder of the operating cylinder according to the present invention has a cylinder tube, a closure part, and another closure part.

[0013] In an actuating cylinder, which is known per se, the cylinder tube has cylinder tube end sections (or cylinder tube end parts) on two opposite sides, that is, it has one cylinder tube end section and another cylinder tube end section. A closure part is arranged on the cylinder tube end section and another closure part is arranged on the other cylinder tube end section. Hereinafter, the cylinder tube end section and the other cylinder tube end section are also collectively referred to as the cylinder tube end section. Accordingly, the closure part and the other closure part are also collectively referred to as the closure part.

[0014] The cylinder tube and the closure parts arranged thereon form the interior of the cylinder. Inside the cylinder, the piston unit forms at least one actuating chamber. The piston unit is preferably designed as a component group composed of a piston and a piston rod. Here, the piston rod slidably passes through one of the closure parts, and accordingly these closure parts become guide closure parts. However, the piston unit can also be provided, for example, as a plunger piston or as a piston unit of a double-rod cylinder.

[0015] Furthermore, the actuating cylinder according to the invention is characterized by a specially designed connecting section.

[0016] The connecting section according to the invention has a closure part, a cylinder tube end section, a segmented connecting ring, and a locking body.

[0017] The elements of the connecting section and their interactions are explained below.

[0018] The closure part is arranged to be inserted axially into the end section of the cylinder tube. In this design, the closure part has a cylindrical outer side surface, also referred to as the outer side surface of the closure part, and the cylinder tube has a cylindrical inner side surface, also referred to as the inner side surface of the cylinder tube. Thus, the closure part is surrounded radially by the inner side surface. Both side surfaces correspond in their diameter, and as a result, the closure part is fixed in its positional relationship to the cylinder tube, where the axial positional relationship is an exception, i.e., the linear degree of freedom along the longitudinal axis of the cylinder is an exception. Optionally, a supporting press fit can also be realized.

[0019] In the end section of the cylinder tube, the cylinder tube has a circumferentially inner annular groove on the inner side surface. Its contour corresponds to the cross-section of the connecting ring, and in the case of a circular connecting ring cross-section, the contour is preferably designed to have a substantially semi-circular shape.

[0020] Furthermore, the closure part has an outer annular groove on its outer side surface that opens on one side in the distal axial direction. The distal axial direction should be understood as the direction away from the axis center of the cylinder. Here, its contour also corresponds to the cross-section of the connecting ring, and in the case of a circular connecting ring cross-section, the contour is preferably designed to be a quarter-circular shape.

[0021] The inner annular groove and the outer annular groove form an annular groove space in which the connecting ring will be arranged. In this design, the connecting ring is surrounded radially by the outer annular groove. Since the outer annular groove in the closure part is designed to open on one side in the axial direction, the annular groove space formed by the two annular grooves is not completely surrounded by either annular groove, but is accessible in the distal axial direction.

[0022] According to the present invention, the connecting ring is segmented by a separating cut. The connecting ring consists of a plurality of connecting ring segments, which are also referred to hereinafter in this specification as ring segments.

[0023] The ring segments are arranged at the separating cut, such that the ring segments are butt-jointed to each other. According to the present invention, the ring segments are placed in a state of substantially contacting each other without a gap due to the butt-jointed configuration. In this design, the surfaces of the separating cut facing the butt-joints are substantially parallel to each other. Further, in the present invention, it is essential that all of the ring segments integrally form a ring body with substantially no gap and extend at an angle of 360 degrees.

[0024] Compared with an elastic piston ring having a piston ring gap, this design has the particular advantage that a continuous ring surface or ring line is provided for power transmission between the groove wall of the inner annular groove and the connecting ring on the one hand and between the connecting ring and the groove wall of the outer annular groove on the other hand.

[0025] According to the present invention, the separating cuts of at least one piston ring segment are designed to open parallel or coaxial to each other. Thus, a surprising solution is found to place the connecting ring in the outer annular groove with substantially no gap in the case of an eccentric joining direction, while this is not possible in the case of a radial separating cut. Being designed parallel means that the separating cuts at one end of the ring segment and at the other end of the ring segment are to be understood as having surfaces parallel to each other. Being designed coaxial means that, on the one hand, the separating cuts have surfaces at one end of the ring segment and at the other end of the ring segment such that their plane levels are substantially parallel to the longitudinal axis of the cylinder, and on the other hand, the separating cuts form an angle that allows the associated ring segment to be pushed in the radial and eccentric directions.

[0026] In the interaction between the outer annular groove and the inner annular groove, the closure part is fixed on one side in a form-fitting manner in the axial distal direction by a connecting ring. In this direction, the total load resulting from the operating pressure is absorbed. Advantageously, the ring surface sections of the inner annular groove and the outer annular groove adapted to fit the connecting ring are provided here with a sufficiently large surface so that an undesirably high surface pressure is avoided.

[0027] Furthermore, the lock body is arranged on the closure part in the axial distal direction by a removable mounting part. The axial distal arrangement should be understood to mean that the lock body is arranged so as to face an opening on one side of the axial distal side of the outer annular groove. The removable mounting part should specifically be understood to be a screw connection of the lock body to the closure part. The lock body can specifically be designed as a ring body if the closure part is a guide closure part, so that a free space for the piston rod is maintained. In the case of the bottom closure part, the lock body can also be designed as a flat cylindrical body. Furthermore, the lock body can also be composed of a plurality of parts.

[0028] The lock body has a circumferential ring surface that establishes pressure contact with the connecting ring and fixes the connecting ring in a form-fitting manner within the annular groove space. The contour of the ring surface can preferably correspond to the cross-section of the connecting ring and can, for example, be substantially quarter-shaped. Thus, the lock body can cover the remaining opening section of the annular groove space. However, other contours are also possible, for example, a partial circular contour of less than 90 degrees, an inclined ring surface without a curved part, or a partial circular contour with a radius different from the connecting ring cross-section, for the purpose of optimizing, for example, pressure contact and thus the fixing of the position of the connecting ring.

[0029] The lock body fixes the closure part on one side in the proximal axial direction by pressing against the connecting ring. Here, the load transmission is realized indirectly through a removable mounting part, which is advantageously problem-free because only a small force caused by, for example, the friction of the piston unit in the guide closure part needs to be absorbed in this direction.

[0030] Since the interaction of the outer annular groove, the connecting ring, and the inner annular groove has already realized the fixation of the position on the axially distal side, the lock body realizes the positional relationship with respect to the cylinder tube in the other opposite axial direction. Here, as a result, the closure part and the cylinder tube are connected in a completely shape-conforming manner.

[0031] The solution according to the present invention specifically has the following advantages.

[0032] On the one hand, a continuous ring surface or ring line for transmitting force between the groove wall of the inner annular groove and the connecting ring and on the other hand between the connecting ring and the groove wall of the outer annular groove avoids non-uniform stress in the groove region of the mating part, reduces, for example, notch stress, and thereby increases the maximum load capacity.

[0033] Another advantage is that the possible load capacity is large because the connecting ring does not need to be elastic due to being segmented, and the connecting ring can have a large cross-section.

[0034] Another advantage is the particularly easy detachability of the connection part. Thus, when having an appropriate design, it becomes possible to disassemble the lock body by using a screwdriver or a wrench with a standard driving device, remove the ring segments, and thereby remove the closure part for inspection or repair purposes.

[0035] In view of this point, the advantage of being easily installed is also reasonable, because before the lock body is to be inserted, the ring segments are already fixed radially outward by the outer annular groove and radially inward by the closure part. Another advantage is the low vulnerability to installation errors, because the lock body cannot be inserted if the ring segments are not properly positioned.

[0036] The simplicity of construction is also particularly advantageous, because the cylinder tube, the closure part, and the lock body can be provided by conventional lathe and milling operations.

[0037] According to a first advantageous development, the actuating cylinder is characterized in that the piston ring has four piston ring segments and all the separating cut parts are oriented parallel to each other.

[0038] According to this development, there are two similar ring segments of the first kind and two similar ring segments of the second kind. Here, the ring segments of the same kind are arranged to face each other. When the two ring segments of the first kind are arranged in the inner annular groove, the two ring segments of the second kind can be inserted in the eccentric direction in the radial direction from the center by the parallel separating cut parts. Thus, the connecting ring can be joined so as to form a substantially gapless ring body that is completely closed by the four ring segments over 360 degrees.

[0039] According to another advantageous development, the actuating cylinder is characterized in that the lock body is arranged to have an axial elastic pre-stress in the proximal direction.

[0040] In the case of a hydraulic actuator, specifically, the connection between the cylinder tube and the closure part is subject to high mechanical stress due to the changing high operating pressure and the accompanying dynamic loads. In the case of a form - fitting connection, this can lead to the formation of unwanted clearances, also known as breathing. Such clearances can be formed when the groove walls of the annular groove and the connecting ring are adapted to each other in shape.

[0041] The elastic pre - stress of the lock body leads to the action of a permanent force on the connecting ring at the ring surface of the lock body. As long as the connecting ring and the groove wall are adapted to each other in shape, this force presses the connecting ring deeper into the annular groove, and as a result, zero clearance is maintained.

[0042] According to another advantageous development based on this design, the actuating cylinder is characterized in that a removable mounting part of the lock body is formed by a clamping screw, each screw head of each clamping screw has a one - sided support part on the lock body and has the action of an axial force on the support part, and the clamping screw exhibits elastic bending in the longitudinal axis.

[0043] According to this another development, the screw head is intended to be placed on the lock body only partially, and preferably in its half. When the clamping screw is tightened by the tightening torque, an eccentric load is applied to the screw head, and as a result, the screw bends in the direction of the non - supported side of the screw head at the free end of the shaft. According to this another development, this bending remains within the range of elastic deformation, and as a result, on the one hand, the screw functions as a spring element that advantageously generates an axial elastic pre - stress of the lock body in the proximal direction, and on the other hand, it also prevents its own loosening at the same time.

[0044] Using a design with such a simple construction, a surprisingly reliable solution for preventing breathing and achieving a particularly long service life of the connection has been found.

[0045] According to another advantageous development form based on this design, the actuating cylinder is characterized in that the circumferential ring surface of the locking body is designed as a cone.

[0046] According to the present invention, the circumferential ring surface establishes a press contact with the connecting ring. In combination with the axial elastic pre-stress of the locking body in the proximal direction, the ring surface inclined as a cone disperses the force on the connecting ring into an axial component and a radial component. Here, the axial component presses the piston ring specifically into the outer annular groove of the closure part, and the radial component presses the piston ring specifically into the inner annular groove of the cylinder, thereby preventing the formation of clearances and the occurrence of bleeding.

[0047] According to another development form, the actuating cylinder is characterized in that the connecting section according to the present invention is arranged on both cylinder tube end sections. Both connecting sections have the same basic structure. As a result, the description of the connecting section is also correspondingly applicable to another connecting section at the opposite end of the cylinder tube. Therefore, a solution is advantageously provided that enables access for inspection or repair at both ends of the actuating cylinder. Furthermore, it is advantageously possible to design the cylinder tube in the same way at both ends and thereby facilitate its manufacture.

[0048] The present invention will be described in more detail below by way of exemplary embodiments with reference to the following figures.

Brief Description of the Drawings

[0049]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0050] Here, the same reference numerals in the various figures always denote the same features or components. Further, the reference numerals are used in this description even if they are not shown in the relevant figures.

[0051] FIG. 1 shows an embodiment of the guide side section of an actuating cylinder, where the connecting section 7 is arranged on the cylinder 1. The cylinder 1 has, here, a closure part 4a designed as a guide closure part and a cylinder tube 3. In this embodiment, a cylinder tube end section 5a designed as a separate sleeve is arranged at the guide side end of the cylinder tube 3. Although not shown here, alternatively, the cylinder tube 3 can also be designed as a monolithic component. The interior 6 is formed by the closure parts 4a, 4b. Further, the piston rod of the piston unit 2 and at least one actuating chamber 6.1, which is thus formed and which is the piston rod chamber in this exemplary embodiment, are shown.

[0052] In addition to the cylinder tube end section 5a, the connecting section 7 has a connecting ring 8 and a lock body 9 having a removable attachment part 10.

[0053] FIG. 2 shows an enlarged view of the connecting section, where in FIG. 2 here, a display without the connecting ring 8 is shown.

[0054] In the cylinder tube end section 5a, the cylinder tube 3 has an inner annular groove 11.1, which is arranged internally on the cylindrical inner side surface of the cylinder tube. In the illustrated embodiment, the inner annular groove 11.1 has a substantially semi-circular contour so as to correspond to the circular cross-section of the connecting ring 8. The opposing closure parts 4a have an outer annular groove 11.2 on their cylindrical outer side surfaces, and the outer annular groove 11.2 has a substantially quarter-circular contour and thus opens axially distally on one side. The two annular grooves 11.1, 11.2 extend across the annular groove space 11.3. In the illustrated embodiment, the lock body 9 has a ring-shaped design and is arranged axially such that its circumferential ring surface 9.1 covers a quarter of the annular groove space that maintains the open state by the two annular grooves 11.1, 11.2. Further, the axially distal side and proximal side are indicated by arrows.

[0055] Figure 3 basically corresponds to Figure 2, but is supplemented with a display of the arrangement of the connecting ring 8 in the annular groove space 11.3 and the interaction of the detachable attachment with the lock body 9 for generating an axial elastic pre-stress.

[0056] The support cone for the head screw provided as the socket screw of the detachable attachment 10 is asymmetric. Here, the support section in the closure part 4a is deeper axially than the support section in the lock body 9. Thus, when the socket screw is screwed in, a unilateral support portion 10.1 is provided to the lock body 9. When the tightening torque is applied, a force is applied to one side with respect to the screw head, causing the socket screw to bend as indicated by the auxiliary line (dashed line). The upper section bends in the longitudinal axis, and the axial plane surface of the screw head tilts. Even when the tightening torque increases, the screw head will be further supported in the deeper support area of the closure part, preventing bending beyond the elastic range and at the same time protecting the socket screw from loosening.

[0057] As a result of the detachable attachment part 10 functioning as an elastic clamping element, the lock body 9 is elastically pre-stressed in the proximal axial direction and transmits a force to the connecting ring 8 via the circumferential ring surface 9.1. The circumferential ring surface is designed as a cone and thus has an inclined contour which advantageously has a force transmission effect as an inclined surface and thus increases the force for pressing the connecting ring into the annular grooves 11.1, 11.2. In this way, advantageously, as a result of large dynamic operating loads, it is prevented that a clearance can be formed which can act in the distal axial direction and cause breathing in the actuating cylinder.

[0058] FIG. 4 shows an overall view which, in addition to FIG. 1, further shows another cylinder tube end section 5b and another closure part 4b provided as a bottom closure part. However, in the exemplary embodiment shown in FIG. 4, a connection according to the invention between the another cylinder tube end section 5b and the another closure part 4b is not provided and here a laser welding connection is realized.

[0059] FIG. 5 shows a variant design consisting of four parts of the connecting ring 8. Here, all the separation cuts 8.1 are aligned parallel. Four connecting ring segments 8.2 are formed by the four separation cuts 8.1.

[0060] FIG. 6 shows a schematic representation of an exemplary embodiment having parallel separation cut portions 8.1, added to FIG. 5. Here, two connecting ring segments 8.2 of the same kind are provided. First, two connecting ring segments of the first kind (shown on the left and right) can be arranged within the inner annular groove 11.1. Then, two connecting ring segments of the second kind (shown on the upper and lower sides) can each be inserted between the connecting ring segments 8.2 of the first kind by an eccentric radial joining movement. The joining movement of each of the connecting ring segments 8.2 of the second kind is indicated by two arrows. After joining, a butt joint contact without gaps between all the connecting ring segments 8.2 is achieved, and as a result, substantially continuous power transmission over a 360-degree range between the cylinder tube 3 and the closure component 4a becomes effective.

[0061] FIG. 7 basically corresponds to FIG. 6, and thus the description given here applies accordingly. However, unlike the embodiment of FIG. 6, the separation cut portion 8.1 of FIG. 7 is designed to be at an angular position that opens in the radial eccentric direction.

[0062] Therefore, during the joining movement of the connecting ring segments 8.2 of the second kind, on the one hand, the joining between the connecting ring segments 8.2 of the first kind is assisted, and on the other hand, a press contact is formed at the separation cut portion 8 by a conical inlet, thereby assisting in arranging the connecting ring segments 8.2 without gaps relative to each other.

[0063] Finally, FIG. 8 shows an axial view of the cylinder 1 without showing the piston unit 2. The connecting ring 8, which is not visible, is represented by two coaxial dashed lines.

[0064] Here, the lock body 9 is designed as a ring body that surrounds the passage of the piston rod in this way. The removable mounting portion 10 is formed by three screws arranged at 120-degree angles, and the head of each screw rests on the lock body using a single-sided support surface 10.1 on one side and further on the support portion on the axial lower side of the closure component 4a.

Explanation of Symbols

[0065] 1 Cylinder 2 Piston Unit 3 Cylinder Tube 4a Closure Component 4b Another Closure Component 5a Cylinder Tube End Section 5b Another Cylinder Tube End Section 6 Inside the Cylinder 6.1 Actuating Chamber 7 Connecting Section 8 Connecting Ring 8.1 Separation Cutting Part 8.2 Connecting Ring Segment 9 Lock Body 9.1 Circumferential Ring Surface 10 Removable Mounting Part 10.1 One-Side Support Part 11.1 Inner Annular Groove 11.2 Outer Annular Groove 11.3 Annular Groove Space

Claims

1. An operating cylinder having a cylinder (1) and a piston unit (2), The cylinder (1) comprises a cylinder tube (3), a closure component (4a), and another closure component (4b), The cylinder tube (3) has a cylinder tube end section (5a) and another cylinder tube end section (5b), the closure component (4a) is located in the cylinder tube end section (5a), and the other closure component (4b) is located in the other cylinder tube end section (5b), The cylinder tube (3) and the closure components (4a, 4b) form the inside of the cylinder (6). The piston unit (2) forms at least one working chamber (6.1) inside the cylinder (6), The cylinder has a closure component (4a), a cylinder tube end section (5a), a connecting ring (8), and a connecting section (7) having a lock body (9). The cylinder tube (3) has a circumferential inner annular groove (11.1) in the cylinder tube end section (5a) on the inner side surface of the cylinder tube, The closure component (4a), having a cylindrical outer surface, is inserted axially into the cylinder tube end section (5a), and the outer surface of the closure component is radially surrounded by the cylindrical inner surface of the cylinder tube of the cylinder tube end section (5a), and has an outer annular groove (11.2) that opens to one side distally in the axial direction. The inner annular groove (11.1) and the outer annular groove (11.2) form an annular groove space (11.3), the connecting ring (8) is positioned within the annular groove space (11.3) and radially surrounded by the inner annular groove (11.1), The connecting ring (8) is segmented by a separation and cutting portion (8.1) and consists of a plurality of connecting ring segments (8.2). The connecting ring segments (8.2) are arranged so as to be butt-jointed with one another at the separation cut portions (8.1), and the separation cut portions (8.1) of at least one piston ring segment (8.2) are designed to open parallel to each other or coaxially to each other. The closure component (4a) is fixed in its designated position on one side by the connecting ring (8) in an axial manner in a shape-adapted manner toward the distal direction. The lock body (9) is positioned on the closure component (4a) in the distal axial direction by a removable mounting portion (10) and has a circumferential ring surface (9.1), the circumferential ring surface (9.1) provides pressure contact with the connecting ring (8) and fixes the connecting ring (8) in the annular groove space in a shape-adapted manner. An operating cylinder in which the lock body (9) fixes the closure component (4a) in the axial direction on one side in the proximal direction in a shape-adapted manner by the pressure contact with the connecting ring (8).

2. The operating cylinder according to claim 1, characterized in that the connecting ring (8) has four connecting ring segments (8.2) and all of the separating and cutting portions (8.1) are designed to be parallel to each other.

3. The operating cylinder according to claim 1, characterized in that the lock body (9) is arranged to have axial elastic prestress in the proximal direction.

4. The operating cylinder according to claim 3, characterized in that the removable mounting portion (10) of the lock body (9) is made of a retaining screw, each screw head of the retaining screw has a one-sided support surface (10.1) on the lock body and has an axial force acting on the one-sided support surface, and the retaining screw exhibits elastic bending with respect to the longitudinal axis.

5. The operating cylinder according to claim 3 or 4, characterized in that the circumferential ring surface (9.1) of the lock body (9) has a conical design.

6. The operating cylinder according to claim 1 or 4, characterized in that the cylinder (1) has another connecting section having another closure component (4b), another cylinder tube end section (5b), another connecting ring, and another locking body, and the other connecting section is designed in the same manner as the connecting section (7).

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