Pressure medium cylinder with static end position seal

Abstract

The present invention provides a pressure medium cylinder (1, 1', 1″, 1″′, 1″″) without a dynamic sealing piston rod (2, 2′), the pressure medium cylinder being able to be cleaned well and reliably from the outside. This is achieved by a pressure medium cylinder (1, 1′, 1″, 1″′, 1″″), which has a cylinder shell (3, 3′); a piston (11, 11′) axially movably arranged in the cylinder shell; and a piston rod (2, 2′) connected to the piston (11, 11′), the piston rod penetrating the cylinder shell (3, 3′) toward the end face through an outlet (15, 15′), wherein the piston rod (2, 2′) has a stop surface (5, 5′, 5″) extending radially from the piston rod (2, 2′) in a section of the piston rod arranged outside the cylinder shell (3, 3′), the stop surface acting on the cylinder shell (3, 3′) in the terminal position when the piston rod (2, 2′) moves in, and here sealingly covering and / or surrounding the piston rod (2, 2′) and the outlet (15′). One or more gap regions (9, 9') between the edges of the piston rod (2, 2') and the outlet (15, 15'). The pressure medium cylinder (1, 1', 1″, 1″′, 1″″) has a static end position seal, which seals the pressure medium cylinder in the end position in the inserted state by the stop surface covering and / or surrounding one or more gap regions (9, 9') between the edges of the piston rod (2, 2') and the outlet (15, 15'). The good and reliable external cleanability of the pressure medium cylinder (1, 1', 1″, 1″′, 1″″) is guaranteed in the inserted state because the stop surface (5, 5', 5″) covers and / or surrounds the outlet (15, 15') in this state.

Description

Technical Field

[0001] This invention relates to a pressure medium cylinder having a static terminal position seal. Background Technology

[0002] A pressure medium cylinder is a fluid-operated drive element used to convert pressure as operating energy into force; the drive element is used, for example, as a drive assembly of a linear actuator. Here, a piston, capable of being loaded with a pressure medium, is arranged in the cylinder housing in an axially movable manner. The movement of machine parts or workpieces is thus achieved through the piston and the piston rod connected to it, which extends out of the cylinder housing at its end face.

[0003] To ensure a sealed internal space, the piston rod outlet is typically equipped with a dynamic annular seal and / or scraper, in which the piston rod, during its piston stroke, moves relative to the sealing member. In this case, the piston rod rubs against the seal. The frictional force permanently present due to the piston rod's movement relative to the sealing member negatively impacts achievable changeover times in highly dynamic applications. Simultaneously, the sealing member suffers relatively high wear, especially in highly dynamic applications, due to frictional loads. Finally, in hygienic design applications, the requirement for good cleanability of such pressure medium cylinders is often only adequately met or only achieved with very high cleaning costs due to dead zones, edges, and gaps created by the sealing member in the piston rod outlet area. Hygienic design principles define the cleanliness requirements for appliances and production equipment specified for food manufacturing. Furthermore, this also requires pressure medium cylinders used in food processing to be advantageously cleanable and sterilizable from the outside after production operations, with chemicals able to drain efficiently, thereby reliably preventing food contamination by microorganisms, material corrosion, or chemicals. Such contamination, for example, cannot be completely and reliably avoided when using ring seals due to the resulting annular gap.

[0004] Documents DE 26 51 398 A1 and DE 10 2015 112 351 A1 disclose pressure medium cylinders having a piston rod extending from an end face and a stop surface located in a piston rod section arranged outside the cylinder housing, extending radially from the piston rod. In the pressure medium cylinder disclosed by DE 26 51 398 A1, the piston rod is guided out of the cylinder body in a sealed manner on both sides. DE 10 2015 112 351 A1 does not disclose its unique technical contribution to solving the sealing problem of the cylinder interior space. Summary of the Invention

[0005] The objective of this invention is to provide a pressure medium cylinder that avoids the disadvantages of the prior art. In particular, it aims to provide a pressure medium cylinder without a dynamically sealing piston rod, which allows for good and reliable external cleaning.

[0006] According to the invention, the task is accomplished by a pressure medium cylinder according to the invention. Advantageous modifications of the invention are indicated in preferred embodiments.

[0007] A pressure medium cylinder forms the core of this invention, comprising a cylinder housing; a piston arranged axially movable within this cylinder housing; and a piston rod connected to the piston, the piston rod penetrating the cylinder housing through an outlet at its end face. The piston rod has a radially extending stop surface in a section of the piston rod disposed outside the cylinder housing. This stop surface acts on the cylinder housing in its terminal position when the piston rod is moved in, and here sealingly covers and / or surrounds one or more gap regions located between the piston rod and the edge of the outlet. Such a pressure medium cylinder has a static terminal position seal, by means of which the pressure medium cylinder is sealed in its terminal position in the moved-in state by the stop surface sealingly covering and / or surrounding one or more gap regions located between the piston rod and the edge of the outlet. In this case, the terminal position of the piston rod in the moved-in state can be defined by the stop surface. The use of a dynamic sealing member is not necessary, thereby reducing friction and increasing the speed of the actuator. This ensures that the pressure medium cylinder can be cleaned reliably and effectively from the outside in the insertion state, as the stop surface seals and / or surrounds the outlet in this state. The pressure medium cylinder can be configured as a single-acting or double-acting cylinder. In the case of a double-acting cylinder (where the piston rod side is also pressure-loaded), leakage is intentionally tolerated. In this case, foreign matter ingress is prevented due to overpressure in the chamber adjacent to the outlet. Especially in highly dynamic applications (e.g., sorting machines), the insertion state occupies only a small fraction of the time; therefore, leakage is acceptable relative to the advantages gained by sacrificing dynamic sealing components. In the case of a single-acting pressure medium cylinder (in which the piston can only be loaded with working fluid in the insertion direction), the risk of foreign matter entering the chamber adjacent to the outlet during operation, especially during the insertion motion, is either tolerated or reduced or prevented by other measures (e.g., by a downwardly tilted mounting position or the addition of a shroud to the pressure medium cylinder). By eliminating dynamic seals, the starting force and friction of the piston rod are significantly reduced compared to the static components of the cylinder housing. This enables operation with shorter transition and response times, especially in highly dynamic applications. Furthermore, downtime and interruptions due to maintenance and repair are significantly reduced because it is unnecessary to replace the wear-prone dynamic seals.

[0008] The sealing fit of the stop surface is improved, or easily guaranteed even under no-pressure conditions, by means of a return spring disposed within the cylinder housing and acting along the direction of piston rod movement. The return spring, in the end position of the piston rod, causes a force-locked engagement between the end face of the cylinder housing and the stop surface.

[0009] Further improvements to the sealing fit are achieved by the stop surface having a sealing body extending radially from or surrounding the piston rod, the sealing body sealingly covering and / or surrounding one or more gap regions located between the piston rod and the edge of the outlet in a sealing manner at the end position. Simultaneously, the sealing body acts as a brake by deforming upon reaching the end position to absorb the kinetic energy of the moving parts, thus applying a braking effect to the piston rod.

[0010] The improved functionality and / or service life of the sealing and braking components can be achieved by the following arrangement: the stop surface is configured with a single brake element extending radially from the piston rod or multiple brake elements arranged radially adjacent to the piston rod, and a seal element extending radially from or surrounding the one or more brake elements, which, in its terminal position, sealably surrounds one or more gap regions located between the piston rod and the outlet edge. In this configuration, the seal element is preferably constructed with a mounting height greater than that of the one or more brake elements and extends beyond the one or more brake elements in the direction toward the cylinder housing end face. Simultaneously, the seal element in this configuration is constructed with greater flexibility than the one or more brake elements due to its shape and / or the material used. Because of the greater mounting height, the seal element acts on the cylinder housing earlier than the one or more brake elements during the piston rod's insertion movement, wherein the seal element, in the event of deformation, applies the initial braking force to the piston rod until the one or more brake elements, constructed with lower flexibility, absorb the majority of the energy. Due to its high flexibility, the seal compresses more than one or more brake elements until it reaches its final position, thereby ensuring a good seal against the cylinder housing. In this configuration, the seal and brake elements can be optimized in terms of materials and construction to ensure the best possible function (sealing or braking) while maximizing their service life.

[0011] In a structurally opposite embodiment, the stop surface is configured with a single brake element extending radially from the seal body or multiple brake elements arranged radially adjacent to the seal body. In this configuration, the seal body is also preferably constructed with a greater mounting height and greater flexibility compared to one or more brake elements. Also in this embodiment, the seal body acts on the cylinder housing earlier during the insertion movement than one or more brake elements and compresses more strongly than one or more brake elements until reaching the terminal position. In this configuration, the seal body and brake elements can also be optimized in terms of materials and construction, i.e., to ensure the best possible function (sealing or braking) while maximizing service life.

[0012] In an alternative embodiment, as a substitute for the stop surface, the cylinder housing may also be constructed with a seal and / or brake in a similar manner at the end face, wherein the seal acts in a sealing manner on the stop surface at the end position of the piston rod during its movement.

[0013] In one structural variation of the pressure medium cylinder, the piston seal is also omitted, thus forming one or more gap regions between the piston and the inner wall of the cylinder housing. In this configuration, the dynamic seal is completely abandoned, thereby minimizing overall starting force and friction and enabling further reduction in switching and response times. In this configuration, additional internal leakage exists between the cylinder chambers formed on both sides of the piston. In embodiments where the pressure medium cylinder is configured as a single-acting cylinder (where the piston can be loaded with working fluid along the ejection direction), the working fluid, during the ejection motion, flows from the loaded cylinder chamber through one or more gap regions formed between the piston and the inner wall of the cylinder housing, toward the unloaded piston side, and ultimately into the surrounding environment through one or more gap regions formed between the piston rod and the edge of the outlet. Therefore, during the ejection motion and ejection position of the piston rod, fluid discharge resists the entry of foreign matter into the cylinder chamber adjacent to the outlet by overpressure. In embodiments where the pressure medium cylinder is configured as a double-acting cylinder (where the piston can also be loaded with working fluid in the insertion direction), in this configuration without dynamic seals, overpressure reliably resists foreign matter ingress during both the insertion and withdrawal movements. To allow the piston rod to enter, the piston is loaded through a cylinder chamber adjacent to the outlet, whereby the working fluid is discharged through one or more gap regions formed between the piston rod and the edge of the outlet, resisting foreign matter ingress until reaching the terminal position of insertion, where a static seal is achieved by a stop surface.

[0014] In another configuration, foreign matter is prevented from entering via one or more gap regions formed between the piston rod and the outlet edge by active overpressure flushing. This is achieved by a cylinder housing configuration having at least one flushing channel that converges into a penetration channel for the piston rod, wherein the loading of the flushing channel occurs simultaneously with the loading of the cylinder chamber. In an embodiment where the pressure medium cylinder is configured as a single-acting cylinder, the flushing channel is also loaded during the withdrawal motion along with the loading of the cylinder chamber, thereby allowing working fluid to reach the penetration channel and be discharged into the surrounding environment through one or more gap regions formed between the piston rod and the outlet edge. Therefore, during the withdrawal motion and in the withdrawal position of the piston rod, fluid discharge prevents foreign matter from entering the cylinder chamber adjacent to the outlet by overpressure. In one embodiment where the pressure medium cylinder is configured as a double-acting cylinder, the flushing passage is also loaded together with the corresponding cylinder chamber during the insertion movement, thereby allowing the working fluid to be discharged during the insertion movement through one or more gap regions formed between the piston rod and the outlet edge, and resisting the entry of foreign matter until reaching the insertion terminal position, where a static seal is achieved by a stop surface.

[0015] In one embodiment where the pressure medium cylinder is configured as a single-acting cylinder, foreign matter is prevented from entering the cylinder chamber adjacent to the outlet by overflowing overpressure during the insertion motion, by constructing the pre-loaded cylinder chamber in a manner that allows for venting through a flushing channel. Attached Figure Description

[0016] The advantages of the present invention will be described in detail below with reference to the accompanying drawings, in conjunction with a description of preferred embodiments. Wherein:

[0017] Figure 1a A schematic partial cross-sectional view of the pressure medium cylinder is shown, with the piston rod already inserted;

[0018] Figure 1b Showing according to Figure 1a A schematic partial cross-sectional view of a pressure medium cylinder, in which the piston rod has been removed;

[0019] Figure 2a A schematic partial cross-sectional view of a pressure medium cylinder according to a second embodiment is shown, wherein the piston rod has been moved in;

[0020] Figure 2b Showing according to Figure 2a A schematic partial cross-sectional view of a pressure medium cylinder, in which the piston rod has been removed;

[0021] Figure 3a A schematic partial cross-sectional view of a pressure medium cylinder according to a third embodiment is shown, wherein the piston rod has been moved in;

[0022] Figure 3b Showing according to Figure 3a A schematic partial cross-sectional view of a pressure medium cylinder, in which the piston rod is in the process of retraction;

[0023] Figure 3c Showing according to Figure 3a A schematic partial cross-sectional view of a pressure medium cylinder, in which the piston rod is in the process of insertion;

[0024] Figure 4a A schematic partial cross-sectional view of a pressure medium cylinder according to a fourth embodiment is shown, wherein the piston rod has been moved in;

[0025] Figure 4b Showing according to Figure 4a A schematic partial cross-sectional view of a pressure medium cylinder, in which the piston rod has been removed;

[0026] Figure 5a A schematic partial cross-sectional view of a pressure medium cylinder according to a fifth embodiment is shown, wherein the piston rod has been moved in;

[0027] Figure 5b Showing according to Figure 5a A schematic partial cross-sectional view of a pressure medium cylinder, in which the piston rod has been removed. Detailed Implementation

[0028] Figure 1a and 1b A first embodiment of the pressure medium cylinder 1 is shown in a schematic partial cross-sectional view. Figure 1a A pressure medium cylinder 1 is shown, having a piston rod 2 in its inserted terminal position. A stop 4 is constructed in a piston rod section arranged outside the cylinder housing 3. The stop 4 has a stop surface 5 extending radially from the piston rod 2, and a sealing body 6, also extending radially from the piston rod 2, is constructed on the stop surface. The end face of the cylinder housing 3 on the piston rod side is formed by a cylinder head 7. In the inserted terminal position of the piston rod 2, the stop 4 acts on the cylinder housing 3 at the end face formed by the cylinder head 7, wherein the sealing body 6 seals over the gap region 9 formed between the piston rod 2 and the penetration channel 8. Here, according to hygienic design specifications, the transition from the stop 4 to the sealing body 6 (which has a flat to slightly convex spherical profile in the terminal position) is constructed flush with the cylinder head 7 without any steps or gaps. Furthermore, the cylinder shell 3 and the stop 4 can be constructed with surfaces having a radius and avoiding horizontality using measures known in hygienic design principles, in order to further improve the discharge of cleaning agents depending on the installation location of the pressure medium cylinder in a specific application context (in Figure 1a and 2b(Not shown in the image). In the shifted-in state, the arrival of the end position of the piston rod 2 is limited by the stop 4 acting on the cylinder housing, in that the stop 4 stops the movement of the piston rod 2 at that instant. At the end position of the piston rod 2... Figure 1a In the terminal position shown, the stop 4 is pressed against the cylinder head 7 of the cylinder housing 3 by a return spring 10 configured as a pressure spring. For this purpose, the return spring 10 is arranged in the cylinder housing 3 between the piston 11 and the inner side of the cylinder head 7 in a pre-tightened manner along the insertion direction. Alternatively, other measures can be used to ensure a sufficient sealing fit of the stop 4 on the cylinder housing 3: for example, by a loaded, inclined mounting position on the piston rod in the insertion state; by pre-tightening the stop 4 along the insertion direction by means of devices arranged on the outer side of the pressure medium cylinder 3, or by arranging magnets in the stop surface 5 and / or in the end face of the cylinder housing 3 formed by the cylinder head 7. To remove the piston rod 2, pressure is applied to the piston 11 through the cylinder chamber 12. The piston 11 is dynamically sealed relative to the inner wall of the cylinder housing 3 by means of a piston seal 13. In the penetration channel 8, the piston rod 3 is slidably guided in the sliding sleeve 14. When the piston rod 2 slides in the penetration channel 8, the sliding sleeve 14 serves only to reduce friction, not to seal the piston rod relative to the penetration channel 8 in a fluid-tight manner. The use of the sliding sleeve 14 is not necessarily necessary; alternatively, the piston rod 2 can be guided directly in the penetration channel 8. For this purpose, the cylinder head 7 and the piston rod 2 are preferably made of mating materials with low wear and low friction relative to each other. The clearance region 9 extends between the sliding sleeve 14 and the piston rod 2 into the internal space of the cylinder housing 3, which in Figure 1a and 1b Due to limitations in drawing techniques, the illustrations are not specially numbered. Figure 1b The section of the pressure medium cylinder 1 on the piston rod side is shown, where the piston rod 2 is in the extended position, in which the stop 4 is released from the cylinder head 7. In this position, the gap region 9 extending between the piston rod 2 and the edge of the outlet 15 of the penetration channel 8 is released. A fluid connection exists between the outlet 15 and the cylinder chamber 16 adjacent to the outlet 15 through the gap region 9. When the loading on the piston 11 through the cylinder chamber 12 is stopped, the piston rod 2 moves into the cylinder housing 3 due to the preload of the return spring 10 until the stop 4 touches the cylinder head 7 in the terminal position. Here, the seal 6 suppresses motion shocks through its elastic deformation and simultaneously acts sealingly on the cylinder head 7 of the cylinder housing 3 by covering the gap region 9 formed between the piston rod 2 and the edge of the outlet 15.

[0029] Figure 2a and 2bA second embodiment of the pressure medium cylinder 1' is shown in a schematic partial sectional view. The pressure medium cylinder 1' has a modified stop 4' configuration compared to the pressure medium cylinder 1. The stop surface 5' is configured with a brake body 17 extending radially from the piston rod 2 and a seal 6' radially surrounding the brake body. The seal 6' has an axially greater mounting height than the brake body 17 and extends beyond the one or more brake bodies toward the cylinder head 7. Simultaneously, the seal 6' has greater flexibility than the brake body 17. Otherwise, the pressure medium cylinder 1' is constructed in the same manner as the pressure medium cylinder 1. Figure 2a A pressure medium cylinder 1' with a piston rod 2 in the inserted terminal position is shown. Figure 2b The section of the pressure medium cylinder 1′ on the piston rod side is shown, where the piston rod 2 is in the extended position, in which the stop 4′ is released from the cylinder head 7. When the loading on the piston 11 through the cylinder chamber 12 is stopped, the piston rod 2 moves into the cylinder housing 3 due to the preload of the return spring 10 until the stop 4′ collides with the cylinder head 7 in the terminal position. In this case, the seal 6′ first acts on the cylinder head 7 of the cylinder housing 3, where the seal deforms. From the corresponding deformation displacement, the brake 17 also acts on the cylinder head 7 of the cylinder housing 3 and absorbs the main part of the kinetic energy by similarly deforming it until the terminal position is reached. The seal 6′ acts sealingly on the cylinder head 7 of the cylinder housing 3 by surrounding the gap region 9 formed between the piston rod 2 and the edge of the outlet 15. Here, also in this embodiment, the transition from the stop 4' to the seal 6' (which has a flat to slightly convex spherical profile at the end position) is constructed flush with the cylinder head 7 without any steps or gaps. Furthermore, the brake 17 structurally restricts the compression of the seal 6', which reduces material fatigue of the seal during its product lifespan and thus improves the reliability of the sealing function in the sense of hygienic design requirements. The material properties of the seal 6' and the brake 17 are configured such that, according to the requirements of the respective application context, kinetic energy is absorbed by the brake 17 in an appropriate manner, and sufficient sealing is ensured by the form-locking fit of the seal 6'. To secure the seal 6' to the stop 4', the seal 6' is constructed with a flange 18 that is bent perpendicularly along the direction of the piston rod 2 and engages in a form-locking manner in a corresponding, circumferential groove 19 located on the side of the stop 4'.

[0030] Figures 3a to 3c A third embodiment of the pressure medium cylinder 1″ is shown in a schematic partial sectional view. The pressure medium cylinder 1″ is configured as a double-acting cylinder in that the cylinder chambers 12′ and 16′ formed on both sides of the piston 11′ can be alternately loaded and vented in opposite directions via a 5 / 2 directional valve 20. Figure 3aA pressure medium cylinder 1″ with a piston rod 2′ in the inserted terminal position is shown. In this position, a stop 4″ acts on the piston rod side end face of the cylinder housing 3′ via a stop surface 5″ extending radially from the piston rod 2′. The cylinder housing 3′ has a seal 6″ formed on its end face that radially surrounds the outlet 15′, which seals against the stop surface 5″ in the inserted terminal position of the piston rod 2′. For fixation, the seal 6″ is fitted in a form-locking manner into a corresponding groove in the form of a side recess on the outer side of the cylinder housing 3′. In this case, according to hygienic design specifications, the transition from the stop 4″ to the seal 6″ and up to the end face of the cylinder housing 3′ is constructed flush without steps or gaps. Furthermore, the transition is constructed without a horizontal surface to ensure that the cleaning fluid is discharged without residue. In the terminal position of the piston rod 2′, the stop surface 5″ seals over the gap region 9′ formed between the piston rod 2′ and the edge of the outlet. The piston 11′ is constructed without a seal, thus a gap region 9″ is also formed between the piston 11′ and the inner wall of the cylinder housing 3′. To remove the piston rod 2′, the cylinder chamber 12′ of the pressure medium cylinder 1″ is pressure-loaded via the 5 / 2 directional valve 20, as... Figure 3b As shown. The piston rod 2′ moves to its outgoing position, where the working fluid, due to overpressure in cylinder chamber 12′, passes through gap region 9″ into cylinder chamber 16′ adjacent to outlet 15′, and from there through gap region 9′ to the surrounding environment via outlet 15′. During the outgoing movement of piston rod 2′ and in the outgoing position, fluid discharge is prevented by overpressure from entering cylinder chamber 16′ adjacent to outlet, where a permanent leak exists. To move piston rod 2′ in, cylinder chamber 16′ of pressure medium cylinder 1″ is pressure-loaded via 5 / 2 directional valve 20, as... Figure 3c As shown. The piston rod 2′ moves to its inserted position, where the working fluid, due to overpressure in cylinder chamber 16′, enters the surrounding environment via gap region 9′ and outlet 15′. During the inserted movement, fluid discharge is prevented by overpressure from allowing foreign matter to enter cylinder chamber 16′ adjacent to the outlet, where permanent leakage exists. In this configuration of the pressure medium cylinder 1″, the return spring 10′ is used to ensure sealing even in the absence of pressure, for example, when the compressed air supply is completely stopped.

[0031] Figure 4a and 4bA fourth embodiment of the pressure medium cylinder 1″′ is shown in schematic partial sectional view. Structural features identical to those of pressure medium cylinder 1″′ are indicated by the same reference numerals. The pressure medium cylinder 1″′ is configured as a single-acting cylinder in that the cylinder chamber 12 can be loaded via a 3 / 2 directional valve 21 in the on position. Furthermore, the pressure medium cylinder 1″′ includes a check valve 22, which prevents the cylinder chamber 12 from venting compressed air from its resting position via the 3 / 2 directional valve 21. When the cylinder chamber 12 is loaded via the 3 / 2 directional valve 21, working fluid arrives in parallel through the flushing passage 23 into the penetration passage 8, as the flushing passage 23 converges into the penetration passage 8. Figure 4b As shown, during the piston rod 2's outward movement and outward position, the working fluid is thus discharged into the surrounding environment through the penetration channel 8 at outlet 15, and foreign matter is prevented from entering the cylinder chamber 16. If the 3 / 2 directional valve 21 returns to its closed rest position, the pre-tensioned return spring 10 in the inward direction causes the piston rod 2 to move in. In this case, the cylinder chamber 12 is not vented through the compressed air outlet of the 3 / 2 directional valve 21 due to the shut-off position of the check valve 22, but instead is vented through the flushing channel 23. Therefore, even during the piston rod 2's inward movement, the working fluid is discharged into the surrounding environment through the penetration channel 8 at outlet 15, and foreign matter is prevented from entering the cylinder chamber 16.

[0032] Figure 5a and 5b A fifth embodiment of the pressure medium cylinder 1″″ is shown in schematic partial sectional view. The same structural features as those of pressure medium cylinder 1″″ are indicated by the same reference numerals. Pressure medium cylinder 1″″ is constructed as a double-acting cylinder in that the cylinder chambers 12 and 16 formed on either side of piston 11 can be alternately loaded and vented in opposite directions via a 5 / 2 directional valve 20′. When cylinder chamber 12 is loaded via the 5 / 2 directional valve 20′, working fluid reaches the penetration channel 8 in parallel through flushing passage 23′, as flushing passage 23′ converges into penetration channel 8. Check valve 22′ opens in this flow direction. Simultaneously, check valve 22″ is used to block the connection from flushing passage 23′ to cylinder chamber 16. Figure 5bAs shown, during the piston rod 2's retraction movement and retraction position, the working fluid is thus discharged into the surrounding environment through the penetration channel 8 at outlet 15, and foreign matter is prevented from entering the cylinder chamber 16. During the piston rod 2's retraction movement and retraction position, the second cylinder chamber 16 is simultaneously vented through the compressed air outlet of the 5 / 2 directional valve 20'. When the cylinder chamber 16 is loaded by the 5 / 2 directional valve 20', the working fluid also arrives in parallel through the flushing channel 23″ that converges into the penetration channel 8. The check valve 22″ opens in this flow direction. Simultaneously, the check valve 22′ is used to block the connection from the flushing channel 23′ to the cylinder chamber 12. Therefore, during the piston rod 2's retraction movement, the working fluid is also discharged into the surrounding environment through the penetration channel 8 at outlet 15, and foreign matter is prevented from entering the cylinder chamber 16. In this configuration of the pressure medium cylinder 1″″, the return spring 10 is used to ensure sealing even in a pressureless state, for example, when the compressed air supply is completely stopped.

[0033] List of reference numerals

[0034] 1, 1′, 1″, 1″′, 1″″ Pressure medium cylinder

[0035] 2, 2' Piston Rod

[0036] 3, 3' Cylinder shell

[0037] 4, 4′, 4″ Stops

[0038] 5, 5′, 5″ Stop surfaces

[0039] 6, 6′, 6″ Sealing body

[0040] 7. Cylinder head

[0041] 8. Penetration Channel

[0042] 9, 9′, 9″ gap area

[0043] 10, 10′ return spring

[0044] 11, 11' Piston

[0045] Cylinder chambers 12, 12′, 16, 16′

[0046] 13 Piston Seals

[0047] 14 Sliding sleeve

[0048] 15, 15′ Exit

[0049] 17 Braking body

[0050] 18 Flanges

[0051] 19 slots

[0052] 20, 20′ 5 / 2 Reversing valve

[0053] 21 3 / 2 Reversing Valve

[0054] 22, 22′, 22″ Check valve

[0055] 23, 23′, 23″ Flushing Channel

Claims

1. A pressure medium cylinder (1, 1', 1”, 1”’, 1””), comprising a cylinder shell (3, 3'); a piston (11, 11') axially movably arranged in the cylinder shell; and a piston rod (2, 2') connected to the piston (11, 11'), the piston rod penetrating the cylinder shell (3, 3') toward an end face through an outlet (15, 15'), characterized in that, An open gap region or multiple open gap regions (9, 9') are formed between the edges of the piston rod (2, 2') and the outlet (15, 15'), through which fluid flows out from the internal space of the cylinder shell (3, 3'), and the piston rod (2, 2') is constructed with a stop surface (5, 5', 5”) extending radially from the piston rod (2, 2') in a piston rod section arranged outside the cylinder shell (3, 3'), the stop surface acting on the cylinder shell (3, 3') in the terminal position when the piston rod (2, 2') moves in, wherein the stop surface (5, 5', 5”) covers and / or surrounds the gap region or multiple gap regions (9, 9') located between the edges of the piston rod (2, 2') and the outlet (15, 15') in a sealing manner.

2. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 1, characterized in that, The cylinder housing (3, 3') is equipped with return springs (10, 10') arranged in the cylinder housing and acting in the direction of movement of the piston rod (2, 2').

3. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 1 or 2, characterized in that, The stop surfaces (5, 5', 5”) are configured with a sealing body (6, 6', 6”) extending radially from or surrounding the piston rod (2, 2'), the sealing body covering and / or surrounding, in a sealing manner, the sealing body in the terminal position, the sealing body covering and / or surrounding, in a sealing manner, the one or more gap regions (9, 9') located between the edges of the piston rod (2, 2') and the outlet (15, 15').

4. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 1 or 2, characterized in that, The stop surface (5, 5', 5”) is configured with a brake body (17) extending radially from the piston rod (2, 2') or a plurality of brake bodies (17) arranged radially adjacent to the piston rod (2, 2'), and is configured with a seal (6, 6', 6”) extending radially from or surrounding the one or more brake bodies (17), the seal body sealingly surrounding the one or more gap regions (9, 9') located between the edges of the piston rod (2, 2') and the outlet (15, 15') in a sealing manner in the terminal position.

5. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 3, characterized in that, The stop surface (5, 5', 5") is configured with a brake element (17) extending radially from the seal (6, 6', 6") or a plurality of brake elements (17) arranged radially adjacent to the seal (6, 6', 6").

6. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 1 or 2, characterized in that, The cylinder shell (3, 3') has a sealing body (6, 6', 6”) extending radially from or surrounding the outlet (15, 15') on its end face. The sealing body acts in a sealing manner on the stop surface (5, 5', 5”) at the end position of the piston rod (2, 2').

7. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 1 or 2, characterized in that, The cylinder housing (3, 3') has a brake body (17) extending radially from the edge of the outlet (15, 15') or a plurality of brake bodies (17) arranged radially adjacent to the edge of the outlet (15, 15') on its end face, and is provided with a seal (6, 6', 6”) extending radially from or surrounding the one or more brake bodies (17), the seal acting in a sealing manner on the stop surface (5, 5', 5”) in the terminal position.

8. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 6, characterized in that, The cylinder housing (3, 3') has a brake body (17) extending radially from the seal (6, 6', 6") on its end face, or a plurality of brake bodies (17) arranged radially adjacent to the seal (6, 6', 6").

9. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 1 or 2, characterized in that, One or more gap regions (9”) are formed between the piston (11, 11') and the inner wall of the cylinder shell.

10. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 1 or 2, characterized in that, The cylinder shell (3, 3') is constructed with at least one flushing channel (23, 23', 23"), which converges into a penetration channel (8) for the piston rod (2, 2'), wherein the loading of the flushing channel (23, 23', 23") is performed together with the loading of the cylinder chamber (12, 12', 16, 16').

11. The pressure medium cylinder (1, 1', 1”, 1”', 1””) according to claim 10, characterized in that, The cylinder chambers (12, 12', 16, 16') can exhaust gas through the flushing passages (23, 23', 23").

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