Working cylinder with end position cushioning

Abstract

The present invention relates to a working cylinder with end position cushioning, wherein a piston unit comprises a piston base body and an annular body. The annular body externally accommodates a piston ring with a piston ring gap. The annular body accommodates a guide pin of the piston base body in a ring opening, wherein the annular gap is formed between the annular body and the guide pin, and wherein the annular body has axial and radial space for movement relative to the piston base body. The annular body has an axial annular surface on the piston base body side, and the piston base body has an axial mating annular surface on the opposite side of the annular body side. The piston unit is constructed so that during the movement into the buffer area, the piston ring axially passes through the pressure medium interface and encloses the buffer pressure medium volume, and has a first operating state during the movement into the buffer area and a second operating state during the movement out, wherein the axial annular surface on the piston base side and the axial mating annular surface on the annular body side abut against each other and form a sealing surface in the first operating state, and the piston ring gap is constructed for the restricted outflow of the buffer pressure medium volume, and wherein the axial annular surface on the piston base side and the axial mating annular surface on the annular body side have an axial gap for the inflow of pressure medium in the second operating state.

Description

Technical Field

[0001] The invention relates to a working cylinder with end position buffering. Background Art

[0002] Various solutions are known from the prior art for constantly or progressively delaying the movement of a piston in a hydraulic working cylinder within a defined area. This delay is usually achieved by means of a buffer, by throttling the outflow of hydraulic fluid. This buffer reduces the cross-section through which the hydraulic fluid can flow.

[0003] For example, EP 0 949 422 B1 discloses a solution in which the annular gap of a damping ring acts as a bottleneck restricting the flow and rests elastically against the cylinder inner wall. To achieve progressive damping, the damping area of the cylinder is designed to be conical. Consequently, with progressive movement in the damping area, the damping ring is compressed, and the annular gap of the damping ring progressively decreases. This is a proven solution that makes a significant contribution to the prior art, but it also places high demands on the manufacturing process due to the necessary precision in the design of the gap dimensions between the piston and the cylinder inner wall.

[0004] Problems arise according to the prior art when bending loads are present, as these lead to deformations in the guide that guides the closure element and in the guide strip of the piston. Furthermore, these lead to relatively large gap dimensions between the piston and the inner wall of the cylinder in order to ensure that the piston does not drag on the inner wall of the cylinder. This hinders the most precise possible damping. Summary of the Invention

[0005] The object of the present invention is to specify a damping for a working cylinder for end position damping, which offers high precision and simple adjustability of the damping and is also suitable for the high bending requirements of the piston unit and for different cylinder construction types, has high reliability and high operational safety, and can also be manufactured simply and cost-effectively.

[0006] This object is achieved by the features listed in embodiment 1. Preferred variants are given by the subordinate embodiments.

[0007] According to the invention, a working cylinder with end position damping comprises a cylinder and piston unit.

[0008] According to the present invention, a cylinder has a cylinder liner, a first closing member, and a second closing member.

[0009] According to the present invention, a first closure component is provided on a first end of the cylinder liner, and a second closure component is provided on a second end of the cylinder liner. The two closure components are arranged so that they are connected to their respective cylinder liner ends in a pressure-tight manner. For this connection, the two closure components are preferably welded along a common annular contact surface with the cylinder liner. Other connections, such as screw connections, are also possible.

[0010] According to the present invention, the cylinder liner and the closure member form a cylinder inner chamber. The cylinder inner chamber refers to the inner chamber of the cylinder formed by the closure member and the cylinder liner, in which the pressure medium is located in the intended application. In addition, the piston is arranged in the cylinder inner chamber.

[0011] According to the invention, the cylinder has a damping region in at least one end region. The damping region is a region of the cylinder interior that provides damping when the piston unit enters.

[0012] Cushioning refers to a force that delays the movement of a piston unit.

[0013] The damping region is located at at least one end region of the cylinder liner and comprises a portion of the cylinder interior space between the pressure medium connection and an axial boundary formed by a closure component arranged on the end region.

[0014] According to the invention, the cylinder has a pressure medium port arranged on the side, wherein the pressure medium port is assigned to the damping region and is axially spaced apart from the axial boundary of the cylinder interior.

[0015] The damping region extends between the pressure medium connection and an axial boundary. The axial boundary physically blocks further movement of the piston unit and thereby unilaterally limits the maximum movement path of the piston unit in the axial direction.

[0016] Preferably, the axial boundary is constructed by the closure member. To this end, the closure member has a corresponding stop face against which the piston unit can rest, thereby it takes its end position.

[0017] In a special embodiment, the end position of the piston unit during operation can also be present before the axial limit is reached.

[0018] According to the present invention, the piston unit comprises a piston base body and an annular body. The piston unit preferably consists of a piston rod and a piston, wherein the piston comprises a piston base body and an annular body. The piston base body and the annular body are also collectively referred to as pistons in the following text.

[0019] The piston base body is designed differently depending on the type of working cylinder. In this way, the piston rod can be guided completely through the piston base body or partially into the piston base body. In addition, the piston unit can be constructed in one piece and only have a piston rod and a piston section.

[0020] According to the present invention, the piston unit slides through the first closure element and forms at least one working chamber in the cylinder interior.

[0021] The first closure part is designed to accommodate the piston unit in a sliding manner and has a sealing element and a guide element for this purpose.

[0022] According to the invention, the piston base body is guided in an axially displaceable manner in the cylinder interior by means of a guide.

[0023] For this purpose, the piston base body has at least one receptacle for a guide. The receptacle is preferably designed as a groove, in which the guide ring is inserted as a guide.

[0024] According to the present invention, the annular body has an annular inner ring groove on its radial outer surface, and the piston ring is arranged in the inner ring groove.

[0025] For this purpose, an annular inner ring groove is designed to accommodate the piston ring and fix it in its axial position. Furthermore, the annular inner ring groove is designed to at least allow radial movement of the piston ring, so that the piston ring can deform elastically. This is achieved by having a sufficient depth of the annular inner ring groove.

[0026] According to the invention, the piston ring rests elastically against the cylinder inner wall and has a piston ring gap.

[0027] For this purpose, the piston ring is designed to be elastic, in particular radially elastic, and in the relaxed state has an outer diameter that is greater than the inner diameter of the cylinder liner.

[0028] If the piston unit is inserted into the cylinder liner, the piston ring becomes a stressed state in the annular inner ring groove so and abuts on the cylinder inner wall. In this stressed state, the piston ring elastically deforms and reduces the size of its outer diameter and the piston ring gap.

[0029] According to the present invention, the annular body accommodates the guide pin of the piston base body in the annular opening, and an annular gap is formed between the radial inner surface of the annular body and the guide pin. The annular opening is preferably a hollow cylindrical recess. However, it can also have another geometry, as long as it is designed so that it is guided by the guide pin. The annular body is designed so that it can be placed on the guide pin of the piston base body via its annular opening.

[0030] The guide pin is an integral part of the piston base. It is preferably a tapered section of the piston base. However, it can also be a connected component. The guide pin is arranged at the end of the piston unit that faces the end position to be cushioned. The guide pin is preferably cylindrical. The outer diameter of the guide pin is smaller than the inner diameter of the ring opening. However, the guide pin can also have any other geometry suitable for guiding the ring body.

[0031] The solution according to the invention is characterized in particular in that the annular body has axial and radial movement space relative to the piston base body. Due to the radial movement space, the annular body is also referred to as a floating annular body in the following text.

[0032] In its position, the annular body is limited in its axial mobility on the guide pin by means of a blocking body. The blocking body is preferably designed as a retaining ring that is inserted into an annular groove provided accordingly on the guide pin. Other blocking body forms that can be provided on the piston base body and axially limit the movement space of the annular body are also possible.

[0033] According to the invention, the annular body has an axial annular surface on the piston base body side, and the piston base body has an axial mating annular surface on the opposite side of the annular body.

[0034] According to the invention, the piston unit is designed to move axially with the piston ring over the pressure medium connection during the movement into the damping region and to enclose a damping pressure medium volume located in the damping region space in the damping region.

[0035] If the piston ring moves past the pressure medium connection during the retraction movement, it reaches the damping area. The damping pressure medium volume is simultaneously enclosed. The pressure medium can no longer flow out of the working chamber directly through the pressure medium connection.

[0036] The buffer zone space represents the portion of the cylinder interior that is bounded by the piston unit, the closure element, and the cylinder liner after the piston ring has passed the pressure medium connection. The buffer zone space decreases with progressive axial movement of the piston unit in the direction of the axial end position.

[0037] The portion of the pressure medium that is enclosed in the buffer region space and flows away from it is called the buffer pressure medium volume.

[0038] According to the present invention, the piston unit is designed to have a first operating state in the damping region during the inward movement and a second operating state in the damping region during the outward movement. The first operating state will also be referred to as the damping operating state hereinafter. The second operating state will also be referred to as the outward operating state hereinafter.

[0039] According to the invention, the axial ring surface on the piston base body side and the axial counter-ring surface on the annular body side bear against each other in a first operating state and form a sealing surface.

[0040] During the retraction movement, the piston unit encloses a damping pressure medium volume, whereby the pressure in the damping region space is increased relative to the pressure at the pressure medium connection.

[0041] According to the invention, there is therefore an excess pressure of the damping pressure medium volume relative to the pressure at the pressure medium connection. According to the invention, the piston ring gap is furthermore designed to dampen the throttled outflow of the pressure medium volume.

[0042] In the damping operating state, the pressure of the enclosed pressure medium, i.e., the pressure of the damping pressure medium volume, exceeds the operating pressure present in the remaining working chamber, so that the annular body, with its axial annular surface on the piston base side, presses against the axial mating annular surface on the annular body side, thereby forming a sealing surface there. The operating pressure is the pressure of the pressure medium at the pressure medium connection, which corresponds to the pressure in the remaining working chamber.

[0043] In the damping operating state, the pressure medium can only flow away through the piston ring gap. By delaying the outflow of the damping pressure medium volume, a force effect is generated, which acts in opposition to the retraction movement of the piston unit.

[0044] According to the present invention, in the second operating state, an axial gap is formed between the axial annular surface on the piston base body side and the axial mating annular surface on the annular body side. This axial gap between the axial annular surface on the piston base body side and the axial mating annular surface on the annular body side will also be referred to as the axial gap in the following text. This is based on the fact that the operating pressure in the extended operating state is greater than the pressure of the damping pressure medium volume in the damping region space. The annular body is separated from the axial mating annular surface on the annular body side of the piston base body, and an axial gap is formed between the piston base body and the annular body.

[0045] According to the invention, the axial gap and the annular gap form a pressure medium inflow channel. The pressure medium inflow channel is designed to allow pressure medium to flow into the damping region space.

[0046] The pressure medium can also flow through the cross section that is retained by the piston ring gap. However, in particular in the case of progressive damping with a conical cross section in the damping region, the cross section of the piston ring gap can be smaller, so that active extension can be particularly delayed and, in addition, a significant pressure loss in the piston ring gap must be overcome for this purpose.

[0047] The axial gap between the axial ring surface on the piston base side of the annular body and the axial mating ring surface on the annular body side of the piston base, as well as the radial annular gap between the radial inner surface of the annular body and the guide pin, both constitute a pressure medium channel, which has a structurally formable cross-section, which is independent of the cross-section of the piston ring gap and allows pressure medium to flow into the buffer area space.

[0048] In this way, the piston unit is moved out of its end position and the damping region without undesired damping occurring. The piston unit thus performs an extension movement.

[0049] Furthermore, it was surprisingly discovered that the annular body and its axial displacement space enable a virtually undelayed extension movement. This is based on the fact that, when pressure is applied to the pressure medium connection, the annular body actively moves axially away from the piston base body. The forces causing these effects are generated by the area of the annular surface on the piston base body and the pressure difference between the pressure at the pressure medium connection and the pressure of the buffer pressure medium in the buffer region space. During its axial displacement, the annular body is designed as a volumetric body and is therefore designed to displace a portion of the volume of the buffer pressure medium in the buffer region space. This results in the pressure medium being pressed against the piston base body and the piston unit being forced out of its end position without delay. This initial phase of the extension operating state only lasts until the piston annular body reaches the spatial end of its axial displacement space above the securing ring. However, in this state, the axial gap is advantageously completely open, allowing pressure medium to flow into the buffer region space through the pressure medium inflow channel, and this uninterrupted extension can continue without undesirable delays.

[0050] The working cylinder with end position cushioning according to the invention has the following advantages in particular:

[0051] The floating rings provide an unexpectedly simple solution to several technical problems at the same time.

[0052] First, the annular body, due to its floating support, is decoupled from the precise radial position of the piston base body. Thanks to the radially elastic piston ring, the annular body always follows the cylinder inner wall precisely in its radial position, self-regulating. This is particularly effective, for example, when the radial position of the piston base body is negatively influenced, particularly by deformation of the piston rod under bending loads.

[0053] A further advantage is that the annular body does not have to transmit radial forces to the inner wall of the cylinder.

[0054] Furthermore, this advantageously makes it possible to provide particularly small gap dimensions between the outer surface of the annular body and the cylinder inner wall without the risk of dragging on the cylinder inner wall, which is not possible according to the prior art.

[0055] Furthermore, it is advantageous that the annular body can provide particularly precise end position damping using one and the same component. This particular precision is based on the fact that the annular body, in its radial position, also follows the cylinder inner wall in the respective damping region, which can in particular be of conical design.

[0056] Furthermore, it is advantageously possible to provide the floating annular body with axial space with particularly low structural expenditure, and thereby to provide two different operating states, a buffering operating state and an outward movement operating state, which on the one hand allow a precise buffering effect during the inward movement and on the other hand allow the avoidance of buffering during the active outward movement.

[0057] Independent of the relative radial position of the annular body and the guide pin in the radial displacement space, the cross section of the annular gap is advantageously always constant and can be determined in a simple manner by the difference between the inner diameter of the annular body and the outer diameter of the guide pin.

[0058] Furthermore, it is advantageous to adapt the damping and run-out characteristics to the respective requirements by simple design measures, such as selecting the axial distance of the pressure medium connection, selecting the shape of the cylinder inner wall in the damping region, selecting the piston ring gap width, or selecting the radial gap width and the ring gap width. Furthermore, this can be done separately for each end position, if specified.

[0059] Furthermore, it is advantageous that, by means of the annular body and its axial displacement space, a non-delayed extension movement can be provided when the annular body is designed as a volumetric body.

[0060] Furthermore, it is advantageous that end position damping can be provided not only in one end position but also in both end positions.

[0061] Furthermore, the solution can be used in different cylinder types, such as, in particular, differential working cylinders, synchronous cylinders, pulling cylinders or plunger cylinders.

[0062] The elastic piston ring, which is loaded against the cylinder inner wall, can also advantageously compensate for production-related deviations of the cylinder liner and thus achieve a high degree of damping precision.

[0063] The advantage resulting from the constant distance of the annular body from the inner wall of the cylinder is that the magnetic position sensor can be used very reliably and provides precise axial position information of the piston unit.

[0064] Finally, it has particular advantages in terms of high reliability, high operational safety and good technical producibility.

[0065] According to an advantageous variant, the axial movement space of the annular body is limited axially opposite the center of the piston by a securing ring. For this purpose, the securing ring is inserted into a groove in the guide bolt, but the securing ring is not completely accommodated in the groove. The securing ring can, in particular, be a snap ring that is available inexpensively as a standardized component.

[0066] In this way, the axial movement space of the annular body is limited in one direction by the axial counterpart annular surface of the piston base body, and the axial movement space of the annular body is limited in the other direction by the securing ring.

[0067] The advantage is that, with a structurally very simple and at the same time reliable device, the axial travel space of the annular body can be determined by means of the axial distance of the securing ring from the annular body, and thus the possible width of the axial gap between the axial annular surface on the piston base body side and the axial mating annular surface on the annular body side, which gap serves as a section of the pressure medium inflow channel. Thus, the possible extension speed in the second operating state can also be influenced in a targeted manner.

[0068] According to another variant, the guide bolt has an axial groove. The axial groove is configured as part of the pressure medium inflow channel. The axial groove is at least one groove extending axially along the guide bolt. The axial groove can also be configured by multiple grooves.

[0069] The axial groove makes it possible to easily widen the cross section of the annular gap and, in combination with the axial gap, to advantageously utilize this cross section for targeted regulation of the pressure medium inflow in the second operating state. This allows the achievable speed of the extension movement in the damping region to be determined. The axial groove advantageously widens the cross section of the pressure medium inflow channel independently of the radial travel space of the annular body.

[0070] According to an advantageous variant, the cylinder has a position sensor which is designed to register the position of the annular body.

[0071] Position sensors detect the position of a piston unit using a measuring method that registers and evaluates changes in capacitive, magnetic, mechanical, or electromagnetic characteristics during the piston's movement. Various position sensors for determining the piston position are known from the prior art. For example, in the case of magnetic structures, detection can be performed using reed switches.

[0072] This variant is particularly advantageous because it allows for particularly precise position detection. The basis for this is that the annular body is supported in a radial space relative to the piston base body, i.e., is supported in a floating manner. The exact radial position of the annular body relative to the cylinder liner remains unaffected by radial positional inaccuracies of the piston base body, since the annular body is guided directly by the inner wall of the cylinder liner via the piston ring. Such radial positional inaccuracies of the piston base body can occur, in particular, due to bending loads, dynamic loads or uneven wear of the guide. As a result, there is always a precise gap size between the annular body and the inner wall of the cylinder, wherein the gap size can also be designed to be significantly smaller than in the prior art. The position sensor is arranged in a fixed position relative to the cylinder liner. It has been found that the accuracy of the axial position detection can be significantly improved by a reliable radial distance between the annular body and the position sensor.

[0073] According to another variant, the cylinder inner wall has a conicity in the damping region, and the piston ring narrows the piston ring gap in the first operating state by means of a progressive retraction movement.

[0074] If the cylinder inner wall has a conical shape in the damping area, the piston ring is subjected to increasing forces during the retraction movement because its outer diameter must be adapted to the increasingly smaller inner diameter of the cylinder inner wall. As a result, the piston ring gap also becomes progressively smaller, and the cross section for the outflow of the damping pressure medium volume becomes smaller.

[0075] The damping effect of the damping area is thus increased to the maximum extent. The degree of the conicity determines the increase in the damping effect in relation to the approach path taken.

[0076] However, the cylinder inner wall can also have a conical section and then a cylindrical section in the damping area during the retraction movement. In this case, the damping effect in the conical area increases to a maximum, while in the subsequent cylindrical section of the damping area, the damping effect, which has already reached a maximum, continues to act continuously until the end position is reached. The course of the damping effect can thus also be adapted to specific requirements.

[0077] According to an advantageous variant, the cylinder has a further damping region in a further end region axially opposite the end region.

[0078] According to an advantageous variant, the cylinder has a further pressure medium connection arranged at the side, wherein the further pressure medium connection is assigned to a further damping region and is axially spaced apart from a further axial boundary of the cylinder interior, which lies opposite the axial boundary.

[0079] The further pressure medium interface, the further damping region and the further axial boundary correspond fundamentally in function and design to the pressure medium interface, the damping region and the axial boundary.

[0080] The further damping region and the further pressure medium connection are spatially adjacent to the second closure element at the second end of the cylinder bushing.

[0081] According to an advantageous variant, the piston unit has a further annular body axially opposite the annular body, and the piston base body has a further guide pin axially opposite the guide pin.

[0082] The other annular body is constructed similarly to the annular body and is arranged on the opposite side of the piston unit. The other guide bolt also has at least one further blocking body that limits the axial movement space of the further annular body. The further blocking body is preferably also constructed as another securing ring that is inserted into another groove in the other guide bolt.

[0083] Despite their fundamentally identical construction, the further annular body and the further guide pin can differ from the aforementioned annular body and guide pin in terms of dimensional deviations. This allows, for example, different damping characteristics to be achieved at the two end positions of the piston unit. This is particularly useful for working cylinders with very asymmetrical loads.

[0084] According to an advantageous variant, the piston unit is designed to have a third operating state during the retraction movement in the other damping region and a fourth operating state during the retraction movement in the other damping region. The third operating state will also be referred to below as the other damping operating state. The fourth operating state will also be referred to below as the other retraction operating state.

[0085] The third operating state is also referred to as another buffer operating state and has the characteristics of the first operating state in a corresponding manner with respect to another buffer area. The fourth operating state is also referred to as another exit operating state and has the characteristics of the second operating state in a corresponding manner with respect to another buffer area.

[0086] The characteristics of the operating state are in particular the pressure ratio, the position of the annular body and the further annular body relative to the piston base body, and the positional relationship of the piston unit relative to the pressure medium connection and the further pressure medium connection.

[0087] A particular advantage of the aforementioned variant is that end position damping is also provided for the double-acting working cylinder, which is effective in both end positions.

[0088] Furthermore, it is advantageous if the damping characteristics of either of the two end position damping can be adjusted independently of the other end position damping. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The present invention is further explained as an embodiment with the aid of the following drawings:

[0090] Figure 1 A working cylinder with end-position damping is shown (section view) as a differential cylinder with one-sided end-position damping.

[0091] Figure 2 The working cylinder with end position damping is shown (enlarged section in the sectional view), which is designed as a differential cylinder and has one-sided end position damping.

[0092] Figure 3 A working cylinder with end-position damping is shown (section), which is designed as a differential cylinder and has double-sided end-position damping.

[0093] Figure 4 A working cylinder with end-position cushioning is shown (section), which is a synchronous cylinder and has double-sided end-position cushioning.

[0094] Figure 5The working cylinder with end position damping is shown in a first operating state (enlarged section in the sectional view), as a differential cylinder with double-sided end position damping.

[0095] Figure 6 The working cylinder with end position damping is shown in a first operating state (enlarged section in the sectional view), as a differential cylinder with double-sided end position damping.

[0096] Figure 7 The piston unit is shown (perspective view). DETAILED DESCRIPTION

[0097] The above description of the solution according to the invention thus includes in particular the various combinations of features defined by the embodiments numbered subsequently:

[0098] 1. Working cylinder with end position buffer,

[0099] It has a cylinder (1) and a piston unit (2),

[0100] The cylinder (1) comprises a cylinder liner (3), a first closing component (4) and a second closing component (5).

[0101] The cylinder liner (3) has a cylinder liner first end (6) and a cylinder liner second end (7),

[0102] wherein the first closing member (4) is arranged on the first end portion (6) of the cylinder liner, and the second closing member (5) is arranged on the second end portion (7) of the cylinder liner,

[0103] The cylinder liner (3) and the closing components (4, 5) form a cylinder inner cavity (8).

[0104] The cylinder (1) has a buffer region (9) in at least one end region.

[0105] The cylinder (1) has at least one pressure medium connection (10) arranged on the side, wherein the pressure medium connection (10) is assigned to the buffer area (9) and is axially spaced apart from the axial boundary (11) of the cylinder inner chamber (8).

[0106] The piston unit (2) comprises a piston base (12) and an annular body (13).

[0107] The piston unit (2) slides through the first closing component (4) and forms at least one working chamber (8a) in the cylinder interior (8).

[0108] The piston base body (12) is guided in an axially displaceable manner in the cylinder inner chamber (8) by means of a guide portion (14).

[0109] The annular body (13) has an annular inner ring groove (16) on its radial outer surface (13c), wherein the piston ring (16) is arranged in the inner ring groove (15).

[0110] The piston ring (16) elastically rests on the cylinder inner wall (17) and has a piston ring gap (16a).

[0111] The annular body (13) accommodates the guide pin (19) of the piston base body (12) in the annular opening (13a), and an annular gap (19) is formed between the radial inner surface of the annular body (13b) and the guide pin (18).

[0112] The annular body (13) has axial and radial movement space relative to the piston base (12).

[0113] The annular body (13) has an axial annular surface (13d) on the piston base body side, and the piston base body has an axial mating annular surface (12a) on the annular body side.

[0114] The piston unit (2) is designed so that during the movement into the damping region (9), the piston ring (16) moves axially past the pressure medium connection (10) and encloses a damping pressure medium volume located in the damping region space (20) in the damping region (9).

[0115] The piston unit (2) is designed so as to have a first operating state during an inward movement and a second operating state during an outward movement in the buffer region (9).

[0116] wherein the axial annular surface (13d) on the piston base body side and the axial mating annular surface (12a) on the annular body side abut against each other in the first operating state and form a sealing surface,

[0117] wherein an excess pressure exists relative to the damping pressure medium volume of the pressure medium connection (10), and the piston ring gap (16a) is designed for a restricted outflow of the damping pressure medium volume,

[0118] The axial ring surface (13d) on the piston base body side and the axial mating ring surface (12a) on the annular body side have an axial gap (21) in the second operating state.

[0119] The axial gap (21) and the annular gap (19) form a pressure medium inflow channel, and the pressure medium inflow channel is designed to allow the pressure medium to flow into the buffer region space (20).

[0120] 2. The working cylinder with end position cushioning according to embodiment 1,

[0121] The axial movement space of the annular body (13) is axially opposite to the center of the piston and is limited by a safety ring (22).

[0122] 3. The working cylinder with end position cushioning according to embodiments 1 and 2,

[0123] The guide pin (18) has an axial groove as part of the pressure medium inflow channel.

[0124] 4. A working cylinder with end position cushioning according to any one of the preceding embodiments,

[0125] The cylinder has a position sensor (23), and the position sensor (23) is designed to register the position of the annular body (13).

[0126] 5. A working cylinder with end position cushioning according to any one of the preceding embodiments,

[0127] The cylinder inner wall (17) has a conicity in the buffer region (20), and the piston ring (16) serves in the first operating state to narrow the piston ring gap (16a) with a progressive retraction movement.

[0128] 6. A working cylinder with end position cushioning according to any one of the preceding embodiments,

[0129] wherein the cylinder (1) has a further buffer region (25) in a further end region axially opposite the end region,

[0130] The cylinder (1) has a further pressure medium connection (26) arranged on the side, wherein the further pressure medium connection (26) is assigned to the further buffer area (25) and is axially spaced from a further axial boundary (27) of the cylinder interior opposite the axial boundary,

[0131] The piston unit (2) has another annular body (28) axially opposite to the annular body (13), and the piston base body (12) has another guide pin (29) axially opposite to the guide pin (18).

[0132] wherein the piston unit (2) is designed so that during the movement into the further damping region (25), the further piston ring (30) axially moves past the further pressure medium connection (26) and encloses in the further damping region (25) a further damping pressure medium volume located in the further damping region space,

[0133] The piston unit is designed so as to have a third operating state during an inward movement in the further damping region (25) and a fourth operating state during an outward movement in the further damping region (25).

[0134] Therein, with respect to the further buffer region (25), the third operating state has characteristics of the first operating state, and the fourth operating state has characteristics of the second operating state.

[0135] Figure 1 An overview of a first exemplary embodiment of a differential cylinder with end position damping is shown. This exemplary embodiment relates to a differential cylinder with end position damping on one side. In this exemplary embodiment, the end position damping is provided in the end position associated with the second closure element 5. This is an end position damping on the piston base, which damps the retraction movement.

[0136] The end-position-damped working cylinder comprises a cylinder 1 and a piston unit 2 .

[0137] The cylinder 1 is composed of a cylinder liner 3, a first closing part 4, and a second closing part 5. The cylinder liner 3 and the two closing parts 4, 5 are connected to each other so that they surround the cylinder inner chamber 8. Here, the first closing part 4 is assigned to the cylinder liner first end 6, and the second closing part 5 is assigned to the cylinder liner second end 7. In this embodiment, the inner side of the second closing part 5 forms an axial boundary 11, and the inner side of the first closing part 5 forms another axial boundary 27, which limit the axial movement space of the piston unit 2 arranged in the cylinder inner chamber 8. The axial boundaries 11, 27 are configured as stop surfaces, which are used for the piston unit 2 that moves axially during operation.

[0138] On the cylinder liner 3 , a pressure medium port 10 is arranged at the cylinder liner second end 7 , and a further pressure medium port 26 is arranged at the cylinder liner first end 6 .

[0139] The piston unit 2 comprises a piston base body 12 and an annular body 13. In this embodiment, the piston unit 2 is composed of a piston rod and a piston that are fixedly connected to each other. In this embodiment, the piston base body and the annular body together constitute the piston.

[0140] In this embodiment, the piston rod of the piston unit 2 is guided through the first closure element 4 and is slidably supported therein.

[0141] The annular body 13 is pushed onto a guide pin 18 which is designed as a constriction on the piston base body 12 .

[0142] The piston basic body 12 is guided in the cylinder liner 3 by means of a guide 14 .

[0143] Figure 2 Show Figure 1 Enlarged view in the area of the second closure element 5 . The piston base element 12 is also located in an end position, whereby the piston base element 12 rests with its guide pin 18 against the axial boundary 11 .

[0144] The arrangement and structure of the annular body 13 are shown in more detail in this figure. In this embodiment, the annular body 13 is constructed as a metal ring having an inner annular groove 15 on its outer surface 13c, in which the piston ring 16 is placed. The inner annular groove 15 is constructed so that the piston ring 16 has a larger movement space in the radial direction, so that the piston ring can deform elastically in the radial direction. The elastic piston ring has a piston ring gap 16a (see in particular for details). Figure 7 ) and bears force against the inner wall 17 of the cylinder.

[0145] The annular body 13 is pushed onto the guide bolt 18 and abuts against the annular body side counterpart annular surface 12a of the piston base body 12 by means of the axial annular surface 13d of the piston base body side. In the axial direction, the axial movement space of the annular body 13 is limited by the securing ring 22.

[0146] Furthermore, the annular opening 13 a of the annular body is designed such that it extends beyond the diameter of the guide pin 18 , so that the annular body has radial room for movement relative to the guide pin 18 .

[0147] The damping area 9 is an axial section and extends from the pressure medium connection 10 to the end position of the piston ring 16 in front of the second closure part 5. During the retraction movement of the piston unit 2, a damping effect is present in the damping area 9, which is directed opposite to the retraction movement direction of the piston unit 2 and suppresses the retraction movement. Figure 5 Detailed description in.

[0148] Figure 3A second embodiment is shown in FIG. This relates to a differential cylinder with cushioning in both end positions. For this purpose, a further annular body 28 is provided. This further annular body 28 is constructed identically to the annular body 13 and is pushed onto a further guide pin 29 and secured there by a further securing ring 30. The two annular bodies 13, 28 and the two guide pins 18, 29 are axially opposed on the piston base body 12.

[0149] The further annular body additionally forms a damping effect in the further damping region 25 in the same manner as in the damping region 9. The further damping region 25 extends between the further pressure medium connection 26 and the end position of the further piston ring 31 in front of the further axial limit 27 on the first closure part 4.

[0150] also, Figure 1 and Figure 3 The differential working cylinders are identical in their basic structure.

[0151] Figure 4 The figure shows a synchronous working cylinder which is also end position-cushioned on both sides. Figure 3 The difference between the differential working piston and the piston rod section of the piston base body 12 is that the piston rod section of the piston base body 12 is guided and slidably supported by two closure parts 4, 5. Therefore, the second closure part 5 is also configured as a guide closure part in this embodiment. The piston base body 12 is similar to Figure 3 The piston unit 2 is constructed in the same manner as the piston base body, but differs in that the piston rod extends through the piston base body. The two sections of the piston unit 2 are also firmly connected to each other here.

[0152] Figure 5 , a first operating state during operation of the working cylinder with end position damping is shown, which is a damping operating state. Figure 6 1 and 2 show a second operating state during operation of the working cylinder with end position damping, which is an extended operating state. These figures serve to illustrate the mode of action of the damping.

[0153] Figure 5 In FIG. 1 , the piston unit is in a retracting motion, and the piston ring 16 in the inner annular groove 15 of the annular body 13 has just passed the pressure medium port 10 and encloses a damping pressure medium volume in the damping region space 20. The pressure in the damping pressure medium volume is greater than the pressure at the pressure medium port 10. Consequently, the annular body 13 is pressed with its piston base-side axial annular surface 13 d against the annular body-side axial counter-annular surface 12 a, thereby forming an annular sealing surface there.

[0154] The pressure medium from the damping pressure medium volume can now only flow back to the pressure medium port 10 via the piston ring gap 16a in the piston ring 16, whereby its damping force acts to hinder the retraction movement of the piston unit 2. The retraction movement is delayed until the piston unit 2 reaches the axial limit 11.

[0155] Figure 6 The second operating state is shown.

[0156] In this second operating state, the piston unit 2 performs an extension movement, which is caused by the pressure medium flowing from the pressure medium connection 10 into the damping region space 20 (as soon as the pressure at the pressure medium connection 10 is greater than the pressure in the damping pressure medium volume).

[0157] As soon as the pressure on the pressure medium connection 10 is greater than the pressure in the buffer pressure medium volume, the annular body 13 is axially displaced and pressed against the securing ring 22. This opens the axial gap 21 between the annular body-side axial mating annular surface 12a and the piston base body-side axial annular surface 13d.

[0158] The annular body 13 also has radial space for movement. This space is provided by an annular gap 19 between the inner surface 13b and the guide pin 18. The axial gap 21 and the annular gap 19 form a continuous pressure medium inflow channel for the pressure medium flowing into the buffer region space 20. In this embodiment, an axial groove 24 in the guide pin additionally increases the flow cross section of the pressure medium inflow channel.

[0159] As a result, the pressure medium can flow into the buffer region space 20 with little pressure loss, and the extension movement is hardly delayed.

[0160] In an embodiment involving double-sided end position cushioning, Figure 5 and Figure 6 The illustrated mode of operation corresponds to the coordinated operation of the third operating state and the fourth operating state in the further damping region 25 by means of the further annular body 28 .

[0161] This includes a third operating state during the entry movement into the further buffer area 25 and a fourth operating state during the exit movement out of the further buffer area 25. In the other end position, the third operating state is the buffer operating state and the fourth operating state is the exit operating state.

[0162] also, Figure 5 and Figure 6 1 and 2 show a position sensor 23 provided on the cylinder liner.

[0163] Figure 7 The piston unit 2 of an exemplary embodiment of a differential cylinder with double-sided end position damping is shown in an oblique view.

[0164] The annular body 13, the piston ring 16 with the piston ring gap 16a, the securing ring 22, the guide 14 and the axial groove 24 are shown. In addition, the further annular body 28 and the further piston ring 31 arranged therein with the further piston ring gap 31a are shown axially opposite the piston base body 12. The piston rings 16, 31 and the securing ring 22 are each formed by an elastic metal ring. The further securing ring and the further guide pin are covered and thus Figure 7 There are no reference numerals in the figures.

[0165] The annular body 13 accommodates the piston ring 16 in the inner annular groove 15 and is fixed to the guide pin 18 by means of the securing ring 22. Corresponding features also apply to the further annular body 28 and the further piston ring 31 as well as the further securing ring and the further guide pin.

[0166] The guide 14 is arranged in a groove of the piston basic body 12 .

[0167] Reference Signs List

[0168] 1 cylinder

[0169] 2 piston units

[0170] 3 cylinder liner

[0171] 4First closing member

[0172] 5 Second closing member

[0173] 6. Cylinder liner first end

[0174] 7. Second end of cylinder liner

[0175] 8-cylinder bore

[0176] 9 buffer area

[0177] 10 Pressure medium interface

[0178] 11 Axial Boundary

[0179] 12 piston base

[0180] 12a Axial mating annular surface on the annular body side

[0181] 13 ring body

[0182] 13a ring opening

[0183] 13b inner surface

[0184] 13c outer surface

[0185] 13d Axial annular surface on the piston base side

[0186] 14 Guidance Department

[0187] 15 inner ring groove

[0188] 16 piston rings

[0189] 16a piston ring clearance

[0190] 17 cylinder inner wall

[0191] 18 guide bolts

[0192] 19 ring gap

[0193] 20 buffer area spaces

[0194] 21 Axial clearance

[0195] 22 safety ring

[0196] 23 Position sensor

[0197] 24 axial grooves

[0198] 25 Another buffer zone

[0199] 26 Another pressure medium interface

[0200] 27 Another Axial Boundary

[0201] 28 Another ring

[0202] 29 Another guide bolt

[0203] 30 Another safety ring

[0204] 31 Another piston ring

[0205] 31a Another piston ring clearance

Claims

1. Working cylinder with end position buffer, It has a cylinder (1) and a piston unit (2), in, The cylinder (1) has a cylinder liner (3), a first closing member (4) and a second closing member (5), The cylinder liner (3) has a cylinder liner first end (6) and a cylinder liner second end (7), wherein the first closing member (4) is arranged on the first end portion (6) of the cylinder liner, and the second closing member (5) is arranged on the second end portion (7) of the cylinder liner, The cylinder liner (3), the first closing component (4) and the second closing component (5) form a cylinder inner cavity (8). The cylinder (1) has a buffer region (9) in at least one end region. The cylinder (1) has at least one pressure medium connection (10) arranged on the side, wherein the pressure medium connection (10) is assigned to the buffer area (9) and is axially spaced apart from the axial boundary (11) of the cylinder inner chamber (8). The piston unit (2) comprises a piston base (12) and an annular body (13). The piston unit (2) slides through the first closing component (4) and forms at least one working chamber in the cylinder interior (8). The piston base body (12) is guided in an axially displaceable manner in the cylinder inner chamber (8) by means of a guide portion (14). The annular body (13) has an annular inner ring groove (15) on its radial outer surface (13c), wherein a piston ring (16) is arranged in the inner ring groove (15). The piston ring (16) elastically rests on the cylinder inner wall (17) and has a piston ring gap (16a). The annular body (13) accommodates a guide pin (18) of the piston base body (12) in an annular opening (13a), wherein the guide pin (18) is implemented as a constriction on the piston base body (12), and an annular gap (19) is formed between the radial inner surface (13b) of the annular body and the guide pin (18). The annular body (13) has axial and radial movement space relative to the piston base (12). The annular body (13) has an axial annular surface (13d) on the piston base body side, and the piston base body has an axial mating annular surface (12a) on the annular body side. The piston unit (2) is designed so that during the movement into the damping region (9), the piston ring (16) moves axially past the pressure medium connection (10) and encloses a damping pressure medium volume located in the damping region space (20) in the damping region (9). The piston unit (2) is designed so as to have a first operating state during an inward movement and a second operating state during an outward movement in the buffer region (9). wherein the axial annular surface (13d) on the piston base body side and the axial counterpart annular surface (12a) on the annular body side abut against each other in the first operating state and form a sealing surface, wherein an excess pressure exists relative to the damping pressure medium volume of the pressure medium connection (10), and the piston ring gap (16a) is designed for a restricted outflow of the damping pressure medium volume, The axial ring surface (13d) on the piston base body side and the axial mating ring surface (12a) on the annular body side have an axial gap (21) in the second operating state. The axial gap (21) and the annular gap (19) form a pressure medium inflow channel, and the pressure medium inflow channel is designed to allow the pressure medium to flow into the buffer region space (20).

2. The end position cushioning working cylinder according to claim 1, It is characterized by: The axial movement space of the annular body (13) is limited by a securing ring (22) in the axial direction opposite to the center of the piston.

3. The working cylinder with end position cushioning according to claim 1, It is characterized by: The guide pin (18) has an axial groove which is designed as part of the pressure medium inflow channel.

4. The working cylinder with end position cushioning according to claim 2, It is characterized by: The guide pin (18) has an axial groove which is designed as part of the pressure medium inflow channel.

5. A working cylinder with end position cushioning according to any one of claims 1 to 4, It is characterized by: The cylinder has a position sensor (23), and the position sensor (23) is designed to register the position of the annular body (13).

6. Working cylinder with end position cushioning according to any one of claims 1 to 4, It is characterized by: The cylinder inner wall (17) has a conicity in the buffer region (9), and the piston ring (16) serves in the first operating state to narrow the piston ring gap (16a) with a progressive retraction movement.

7. The working cylinder with end position cushioning according to claim 5, It is characterized by: The cylinder inner wall (17) has a conicity in the buffer region (9), and the piston ring (16) serves in the first operating state to narrow the piston ring gap (16a) with a progressive retraction movement.

8. Working cylinder with end position cushioning according to any one of claims 1 to 4 and 7, It is characterized by: The cylinder (1) has a further buffer region (25) in a further end region axially opposite the end region, The cylinder (1) has a further pressure medium connection (26) arranged on the side, wherein the further pressure medium connection (26) is assigned to the further buffer area (25) and is axially spaced from a further axial boundary (27) of the cylinder interior opposite the axial boundary (11), The piston unit (2) has another annular body (28) axially opposite to the annular body (13), and the piston base body (12) has another guide pin (29) axially opposite to the guide pin (18). The piston unit (2) is designed so that during the movement into the further damping region (25), the piston unit (2) moves axially with the further piston ring (31) past the further pressure medium connection (26) and encloses in the further damping region (25) a further damping pressure medium volume located in the further damping region space. The piston unit is designed so as to have a third operating state during an inward movement in the further damping region (25) and a fourth operating state during an outward movement in the further damping region (25). Therein, with respect to the further buffer region (25), the third operating state has characteristics of the first operating state, and the fourth operating state has characteristics of the second operating state.

9. The working cylinder with end position cushioning according to claim 5, It is characterized by: The cylinder (1) has a further buffer region (25) in a further end region axially opposite the end region, The cylinder (1) has a further pressure medium connection (26) arranged on the side, wherein the further pressure medium connection (26) is assigned to the further buffer area (25) and is axially spaced from a further axial boundary (27) of the cylinder interior opposite the axial boundary (11), The piston unit (2) has another annular body (28) axially opposite to the annular body (13), and the piston base body (12) has another guide pin (29) axially opposite to the guide pin (18). The piston unit (2) is designed so that during the movement into the further damping region (25), the piston unit (2) moves axially with the further piston ring (31) past the further pressure medium connection (26) and encloses in the further damping region (25) a further damping pressure medium volume located in the further damping region space. The piston unit is designed so as to have a third operating state during an inward movement in the further damping region (25) and a fourth operating state during an outward movement in the further damping region (25). Therein, with respect to the further buffer region (25), the third operating state has characteristics of the first operating state, and the fourth operating state has characteristics of the second operating state.

10. The working cylinder with end position cushioning according to claim 6, It is characterized by: The cylinder (1) has a further buffer region (25) in a further end region axially opposite the end region, The cylinder (1) has a further pressure medium connection (26) arranged on the side, wherein the further pressure medium connection (26) is assigned to the further buffer area (25) and is axially spaced from a further axial boundary (27) of the cylinder interior opposite the axial boundary (11), The piston unit (2) has another annular body (28) axially opposite to the annular body (13), and the piston base body (12) has another guide pin (29) axially opposite to the guide pin (18). The piston unit (2) is designed so that during the movement into the further damping region (25), the piston unit (2) moves axially with the further piston ring (31) past the further pressure medium connection (26) and encloses in the further damping region (25) a further damping pressure medium volume located in the further damping region space. The piston unit is designed so as to have a third operating state during an inward movement in the further damping region (25) and a fourth operating state during an outward movement in the further damping region (25). Therein, with respect to the further buffer region (25), the third operating state has characteristics of the first operating state, and the fourth operating state has characteristics of the second operating state.

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