High-pressure globe valves for gaseous media

Abstract

The present invention discloses a high-pressure stop valve for gas medium, including a valve body, an actuator, a valve seat, a valve stem and a sealing assembly A, wherein the valve cavity includes a flow channel, and an air inlet and an air outlet are respectively arranged at both ends of the flow channel, and the air inlet is located on the side of the air outlet close to the actuator; the valve seat is annular, and its outer annular surface is connected to the flow channel wall, and a sealing ring is installed on its inner annular surface; the valve stem is a secondary stepped shaft, and its large diameter end is connected to the driving end of the actuator, and its small diameter end is inserted into the valve body, and a sealing part is arranged between the large diameter shaft and the small diameter shaft of the valve stem. During the whole process of high-pressure fluid flowing through the valve body, since the fluid only contacts the side wall of the valve stem, it will not generate thrust with any part of the cross section of the projection surface on the valve stem, and then the pressure fluid will not generate an upward force on the valve stem, so that the connection part between the valve stem and the actuator in the axial fixed position will not be damaged, thereby improving the service life of the valve.

Description

Technical Field

[0001] The invention relates to the technical field of stop valves, in particular to a high-pressure stop valve for gaseous media. Background Art

[0002] The stop valve, also called the cut-off valve, is the most widely used valve. The reason why it is so popular is that the friction between the sealing surfaces is small during the opening and closing process, it is relatively durable, the opening height is not large, it is easy to manufacture and maintain, and it is not only suitable for medium and low pressure, but also for high pressure. The closing principle of the stop valve is to rely on the valve stem pressure to make the valve disc sealing surface fit closely with the valve seat sealing surface to prevent the flow of the medium. The valve plays an important role in cutting off and throttling the medium in the pipeline where it is located. As an extremely important cut-off valve, the stop valve is sealed by applying torque to the valve stem. The valve stem applies pressure to the valve disc in the axial direction, so that the valve disc sealing surface fits closely with the valve seat sealing surface to prevent the medium from leaking along the gap between the sealing surfaces.

[0003] In the existing stop valve, the axis of the air inlet and the air outlet is parallel and perpendicular to the moving direction of the valve stem, resulting in that during the process of opening the valve, the high-pressure fluid first enters the air inlet, then moves upward for a distance, contacts the valve core and valve seat, and then enters the air outlet. When the valve cavity of this structure is working, the high-pressure fluid will generate an upward thrust on the valve core of the stop valve. Since the valve stem is fixed in axial position by the actuator when the valve is in the passage, the upward thrust of the high-pressure fluid on the valve core will damage the connection between the valve stem and the actuator, which has a negative impact on the service life of the valve. Summary of the invention

[0004] The purpose of the present invention is to provide a high-pressure stop valve for gas medium, which solves the problem that in the existing stop valve, the upward thrust of the high-pressure fluid on the valve core will damage the connection between the valve stem and the actuator, which has a negative impact on the service life of the valve.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A high-pressure stop valve for gas medium comprises a valve body, an actuator fixed on the valve body, a valve seat located in a valve cavity of the valve body, a valve stem connected to the actuator at one end and inserted into the valve cavity at the other end and capable of sealing with the valve seat, and a sealing assembly A for sealing the mating portion between the valve stem and the valve body, wherein the valve cavity comprises a flow channel whose axis coincides with the axis of the valve stem, an air inlet and an air outlet are respectively arranged at both ends of the flow channel, and the air inlet is located on the side of the air outlet close to the actuator; the valve seat is annular, and its outer annular surface is connected to the flow channel wall, and a sealing ring is installed on its inner annular surface; the valve stem is a two-stage stepped shaft, and its large-diameter end is connected to the driving end of the actuator, and its small-diameter end is inserted into the valve body; a sealing portion is arranged between the large-diameter shaft and the small-diameter shaft of the valve stem, and the flow channel is cut off when the sealing portion cooperates with the sealing ring, and the flow channel is in a passage state when the small-diameter shaft is opposite to the sealing ring.

[0007] Furthermore, an annular groove whose axis coincides with the axis of the valve stem is provided inside the valve body, the valve body comprises an upper valve body and a lower valve body connected in sequence, the air inlet, the upper side of the flow channel and the upper side of the annular groove are located on the upper valve body, and the air outlet, the lower side of the flow channel and the lower side of the annular groove are located on the lower valve body;

[0008] The outer ring surface of the valve seat is convex to form a fixing ring that matches the annular groove;

[0009] The actuator is fixed on the upper valve body.

[0010] Furthermore, the inner diameter of the valve seat increases synchronously from the contact surface between the upper valve body and the lower valve body to the upper and lower sides.

[0011] Furthermore, the valve seat is divided into an upper valve seat and a lower valve seat by the contact surface between the valve body and the lower valve body, and an annular right-angle groove is provided on the surface of the upper valve seat opposite to the lower valve seat, and the portion of the lower valve seat opposite to the right-angle groove is convex outward to form a ring body with a right-angled triangle cross section, the surface where the right-angled side is located is connected to the lower valve seat, the surface where the other right-angled side is located is the inner annular surface of the ring body, and the hypotenuse is stepped;

[0012] The cross-section of the sealing ring is a right-angled trapezoid, and its lower base and the surface where the right-angled waist are located are respectively in contact with the two groove walls of the right-angled groove, and its beveled waist is stepped and matched with the beveled edge of the ring body, and the right angle between its upper base and the right-angled waist is in contact with the sealing part, and there is a linear seal between the sealing part and the sealing ring.

[0013] Furthermore, a guide rod is provided at the small diameter end of the valve stem, the axis of the guide rod coincides with the axis of the valve stem, one end of the guide rod is connected to the valve stem, and the other end thereof passes through the valve body, and the guide rod is sealed with the valve body through a sealing assembly B.

[0014] Furthermore, a sealing cover is connected to the portion of the valve body through which the guide rod passes, and the sealing cover covers the guide rod.

[0015] Furthermore, the actuator is fixed to the valve body through a connecting assembly, which includes a support tube, a screw B and a connecting plate. The connecting plate is fixed to the valve body, one end of the support tube is connected to the connecting plate, and the other end thereof is in contact with the outer casing of the actuator. The rod end of the screw B passes through the center holes of the connecting plate and the support tube in turn and is threadedly connected to the outer casing of the actuator.

[0016] Furthermore, the actuator is a single-acting cylinder, and the large-diameter end of the valve stem is connected to the end of the piston rod of the single-acting cylinder.

[0017] Due to the adoption of this technical solution, the beneficial effects of the present invention are:

[0018] 1. The high-pressure stop valve for gas medium of the present invention, when the valve is opened, the valve stem is moved upward by the actuator so that when the small-diameter shaft and the sealing ring are in the same axial position, the flow channel is in a passage state; then the high-pressure fluid at the air inlet enters the air outlet along the flow channel; during the whole process of the high-pressure fluid flowing through the valve body, since the fluid only contacts the side wall of the valve stem, no thrust is generated with any part of the cross section of the projection surface of the valve stem, and then the pressure fluid does not generate an upward force on the valve stem, thereby not damaging the connection part between the valve stem and the actuator in the axial fixed position, thereby improving the service life of the valve;

[0019] 2. The high-pressure stop valve for gas medium of the present invention realizes the cutoff of the flow channel through the linear seal between the sealing part and the sealing ring, that is, the sealing is achieved by forming a line contact between the sealing part and the sealing ring, which can reduce the sealing pressure ratio, and the closing action of the valve can be completed with a smaller driving force, which is convenient for using a smaller actuator and is conducive to the installation of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work. The proportional relationship of each component in the drawings of this specification does not represent the proportional relationship in actual material selection and design, which is only a schematic diagram of the structure or position, where:

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 The present invention Figure 1 A partial enlarged view of the .

[0023] Description of the reference numerals in the accompanying drawings:

[0024] 1-screw A, 2-lower valve body, 3-O-ring A, 4-lower valve seat, 5-O-ring B, 6-upper valve body, 7-O-ring C, 8-O-ring D, 9-pressing sleeve, 10-O-ring E, 11-support cylinder, 12-screw B, 13-linear drive mechanism, 14-nut, 15-screw C, 16-connecting plate, 17-valve stem, 18-upper valve seat, 19-sealing ring, 20-composite bearing, 21-guide rod, 22-screw D, 23-O-ring F, 24-cover, 25-valve body, 26-valve seat, 27-flow channel, 28-air inlet, 29-air outlet, 30-sealing part, 31-actuator. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0027] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0028] Combine the following Figure 1 , Figure 2 The present invention is described in detail.

[0029] Example 1

[0030] like Figure 1-Figure 2As shown, the high-pressure stop valve for gas medium of the present invention comprises a valve body 25, an actuator fixed on the valve body 25, a valve seat 26 located in the valve cavity of the valve body 25, a valve stem 17 connected to the actuator at one end and inserted into the valve cavity at the other end and capable of sealing with the valve seat 26, and a sealing assembly A for sealing the matching part between the valve stem and the valve body 25, wherein the valve cavity comprises a flow channel 27 whose axis coincides with the axis of the valve stem 17, and an air inlet 28 and an air outlet 29 are respectively arranged at both ends of the flow channel 27, and the air inlet 28 and the air outlet 29 are respectively arranged at the two ... 8 is located on the side of the air outlet 29 close to the actuator; the valve seat 26 is annular, and its outer ring surface is connected to the flow channel wall, and a sealing ring 19 is installed on its inner ring surface. The valve stem 17 is a two-stage stepped shaft, and its large diameter end is connected to the driving end of the actuator, and its small diameter end is inserted into the valve body 25. A sealing portion 30 is provided between the large diameter shaft and the small diameter shaft of the valve stem 17. When the sealing portion 30 cooperates with the sealing ring 19, the flow channel 27 is cut off, and when the small diameter shaft is opposite to the sealing ring 19, the flow channel 27 is in a passage state.

[0031] The sealing assembly A includes a pressing sleeve 9, an O-ring C7, an O-ring D8 and an O-ring E10. A three-level stepped hole is provided at the position of the valve body 25 that seals with the valve stem 17. The hole diameter gradually decreases as it approaches the flow channel 27. As the hole diameter decreases, each hole is sequentially a first-level stepped hole, a second-level stepped hole and a third-level stepped hole. The pressing sleeve 9 is a three-level stepped shaft with a central hole. As its outer diameter decreases, each shaft section is sequentially a first-level stepped shaft, a second-level stepped shaft and a third-level stepped shaft. A plurality of annular grooves are provided, and an O-ring D8 is installed in each annular groove, and the inner ring of the O-ring D8 is interference fit with the large diameter section of the valve stem 17; the O-ring C7 is installed in the three-level stepped hole; the three-level stepped shaft is inserted into the three-level stepped hole and pressed on the O-ring C7, and the secondary stepped shaft is threadedly connected with the secondary stepped hole; an annular groove is provided on the outer wall of the primary stepped shaft, and the O-ring E10 is installed in this annular groove, and the outer ring of the O-ring E10 is interference fit with the wall of the stepped hole. The O-ring is preferably hydrogenated nitrile rubber.

[0032] In actual assembly, the sealing component A may also adopt other structures, and its specific structural form is not limited, and all structures known in the art for shaft hole sealing may be adopted.

[0033] The actuator may be a pneumatic cylinder, such as a single-acting pneumatic cylinder, or a pneumatic diaphragm mechanism, or a screw and an internal threaded barrel that cooperate to achieve axis movement through rotation.

[0034] In the present invention, when the valve is opened, the valve stem 17 is moved upward by the actuator so that the small-diameter shaft and the sealing ring 19 are in the same axial position, and the flow channel 27 is in a passage state; then the high-pressure fluid at the air inlet 28 enters the air outlet 29 along the flow channel 27. During the entire process of the high-pressure fluid flowing through the valve body, since the fluid only contacts the side wall of the valve stem, no thrust is generated with any part of the cross section of the projection surface of the valve stem, and then the pressure fluid does not generate an upward force on the valve stem, thereby not damaging the connection part between the valve stem and the actuator in the axial fixed position, thereby improving the service life of the valve.

[0035] Example 2

[0036] This embodiment further illustrates the structure of the valve body 25 based on the embodiment 1.

[0037] like Figure 1-Figure 2 As shown, in the present invention, an annular groove whose axis coincides with the axis of the valve stem 17 is provided inside the valve body 25, and the valve body 25 includes an upper valve body 6 and a lower valve body 2 connected in sequence, the air inlet 28, the upper side of the flow channel 27 and the upper side of the annular groove are located on the upper valve body 6, and the air outlet 29, the lower side of the flow channel 27 and the lower side of the annular groove are located on the lower valve body 2;

[0038] The outer ring surface of the valve seat 26 is convex to form a fixed ring that cooperates with the annular groove;

[0039] The actuator is fixed on the upper valve body 6 , and the three-stepped hole is arranged on the upper valve body 6 .

[0040] When the valve seat 26 is integrally formed with the valve body, it is not convenient to process the valve seat 26 and the flow channel surface and the installation position of the sealing ring 19, and it is not convenient to install the sealing ring 19; therefore, in order to reduce processing costs and improve processing quality, it is preferred to separate the valve seat from the valve body and divide the valve body into an upper valve body 6 and a lower valve body 2. The upper valve body 6 and the lower valve body 2 can be sealed and fixed to each other by means of girth welding, flange bolt connection, etc. after the valve seat 26 is assembled. This is convenient for processing the valve seat 26 and the flow channel surface, improving the surface quality, and facilitating the installation of the valve seat 26, because the valve seat 26 is clamped between the upper valve body 6 and the lower valve body 2.

[0041] Example 3

[0042] This embodiment is based on the above embodiment and describes the structure of the valve seat 26 .

[0043] like Figure 1-Figure 2 As shown, in the present invention, the inner diameter of the valve seat 26 increases synchronously from the contact surface between the upper valve body 6 and the lower valve body 2 to the upper and lower sides, so as to facilitate the guidance of the pressure fluid, reduce the erosion of the valve seat, and ensure the matching position between the valve seat and the valve stem.

[0044] Furthermore, the valve seat 26 is divided into an upper valve seat 18 and a lower valve seat 4 by the contact surface between the valve body 6 and the lower valve body 2. An annular right-angle groove is provided on the surface of the upper valve seat 18 opposite to the lower valve seat 4. The portion of the lower valve seat 4 opposite to the right-angle groove is convex outward to form a ring body with a right-angled triangle cross section, the surface where the right-angle side is located is connected to the lower valve seat 4, the surface where the other right-angle side is located is the inner annular surface of the ring body, and the hypotenuse is stepped;

[0045] The cross-section of the sealing ring 19 is a right-angled trapezoid, and its lower base and the surface where the right-angled waist are located are respectively in contact with the two groove walls of the right-angled groove, and its beveled waist is stepped and matched with the beveled edge of the ring body. The right angle between its upper base and the right-angled waist is in contact with the sealing part 30, so that there is a linear seal between the sealing part and the sealing ring 19.

[0046] The sealing part can preferably be a curved surface such as a cone, a spherical surface, a parabola, etc., and the distance between the sealing part and the valve stem axis preferably gradually decreases along the flow direction of the fluid in the flow channel.

[0047] The flow channel is cut off by a linear seal between the sealing portion and the sealing ring 19, that is, a line contact is formed between the sealing portion and the sealing ring 19 to achieve sealing, which can reduce the sealing pressure ratio and complete the closing action of the valve with a smaller driving force, making it easier to use a smaller actuator and facilitating the installation of the present invention.

[0048] Example 4

[0049] This embodiment further illustrates the support mechanism of the valve stem 17 .

[0050] like Figure 1 As shown, in the present invention, a guide rod 21 is provided at the small diameter end of the valve stem 17, the axis of the guide rod 21 coincides with the axis of the valve stem 17, one end of the guide rod 21 is connected to the valve stem 17, and the other end thereof passes through the valve body 25, and the guide rod 21 is sealed with the valve body 25 through a sealing assembly B.

[0051] The valve stem as a whole is supported and limited by the valve seat, the sealing assembly A and the actuator at most, while the end of the small diameter section of the valve stem 17 is in a suspended state, which is not convenient for ensuring that the valve stem is radially fixed. The suspended end will bear the radial thrust from the fluid, which is not conducive to the valve stem to ensure the required coaxiality. Therefore, in the present invention, the suspended end of the valve stem is supported and limited by the guide rod 21 to prevent the suspended end of the valve stem from deviating from the preset position due to radial force, thereby ensuring the coaxiality of the valve stem and its various supporting parts, and improving the service life and sealing performance of the present invention.

[0052] The structure of sealing component B is consistent with that of sealing component A and is symmetrical to each other. The inner ring of the O-ring D8 in sealing component B is interference fit with the guide rod 21, and the three-level stepped hole that cooperates with sealing component B is set on the lower valve seat 4.

[0053] The valve stem 17 and the guide rod 21 are connected by a screw, one end of the screw is connected to the valve stem, and the other end of the screw is inserted into the guide rod 21 and threadedly connected thereto.

[0054] When the guide rod 21 is provided, the positions of the air inlet 28 and the air outlet 29 can be interchanged without being restricted by the flow direction of the fluid.

[0055] Furthermore, a sealing cover 24 is connected to the portion of the valve body 25 through which the guide rod 21 passes, and the sealing cover 24 covers the guide rod 21 .

[0056] The provision of the cover 24 prevents the end of the guide rod 21 extending outside the valve body from being hit by foreign objects.

[0057] Example 5

[0058] This embodiment is an implementation description of the execution mechanism.

[0059] The actuator is fixed to the valve body 25 through a connecting assembly, which includes a support tube 11, a screw B12 and a connecting plate 16. The connecting plate 16 is fixed to the valve body 25. One end of the support tube 11 is connected to the connecting plate 16, and the other end thereof is in contact with the outer casing of the actuator. The rod end of the screw B12 passes through the center holes of the connecting plate 16 and the support tube 11 in turn and is threadedly connected to the outer casing of the actuator.

[0060] Furthermore, the actuator is a single-acting cylinder, and the large-diameter end of the valve stem 17 is connected to the end of the piston rod of the single-acting cylinder.

[0061] The valve stem 17 and the piston rod are connected by a screw, one end of the screw is connected to the valve stem, and the other end of the screw is inserted into the piston rod and threadedly connected thereto.

[0062] The connecting plate 16 is fixed to the valve body with screws C. Figure 1 In the example, screw C and screw B do not interfere with each other, but are located at different circumferential positions. Figure 1 It is only for the purpose of clearly showing the positions of screw C and screw B relative to the axis without enlarging the radial dimension.

[0063] Example 6

[0064] This embodiment is to illustrate the implementation of the air inlet 28 and the air outlet 29 in the present invention.

[0065] There are multiple air inlets 28 and air outlets 29, preferably two each. Figure 1 As shown, the air inlet 28 is port A and port B, and the air outlet 29 is port C and port D. A and B take in air at the same time or only one of them takes in air and the other is sealed, and C and D exhaust air at the same time or only one of them exhausts air and the other is sealed.

[0066] When the present invention is used to transport special gases such as oxygen, the valve is preferably made of copper material, preferably H62 brass, to avoid sparks caused by friction between the gas and the flow channel wall when the gas flows. Brass valves can well prevent sparks caused by friction when transporting oxygen. The valve stem and connecting rod are preferably made of QBe2 material.

[0067] The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be thought of by a person skilled in the art within the technical scope disclosed by the present invention without creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. A high-pressure stop valve for gaseous media, comprising a valve body (25), an actuator fixed to the valve body (25), a valve seat (26) located in a valve cavity of the valve body (25), a valve stem (17) one end of which is connected to the actuator and the other end of which is inserted into the valve cavity and can be sealed with the valve seat (26), and a sealing assembly A for sealing the fitting portion between the valve stem and the valve body (25), characterized in that: The valve cavity comprises a flow channel (27) whose axis coincides with the axis of the valve stem (17); an air inlet (28) and an air outlet (29) are respectively arranged at both ends of the flow channel (27); and the air inlet (28) is located on the side of the air outlet (29) close to the actuator; the valve seat (26) is annular, and its outer annular surface is connected to the flow channel wall, and a sealing ring (19) is installed on its inner annular surface; the valve stem (17) is a two-stage stepped shaft, and its large diameter end is connected to the driving end of the actuator, and its small diameter end is inserted into the valve body (25); a sealing portion (30) is arranged between the large diameter shaft and the small diameter shaft of the valve stem (17); when the sealing portion (30) cooperates with the sealing ring (19), the flow channel (27) is cut off; when the small diameter shaft is opposite to the sealing ring (19), the flow channel (27) is in a passage state; An annular groove whose axis coincides with the axis of the valve stem (17) is provided inside the valve body (25); the valve body (25) comprises an upper valve body (6) and a lower valve body (2) which are connected in sequence; the air inlet (28), the upper side of the flow channel (27) and the upper side of the annular groove are located on the upper valve body (6); the air outlet (29), the lower side of the flow channel (27) and the lower side of the annular groove are located on the lower valve body (2); the outer annular surface of the valve seat (26) is convex to form a fixing ring which cooperates with the annular groove; the actuator is fixed on the upper valve body (6); The inner diameter of the valve seat (26) increases synchronously from the contact surface between the upper valve body (6) and the lower valve body (2) to the upper and lower sides; The valve seat (26) is divided into an upper valve seat (18) and a lower valve seat (4) by the contact surface between the upper valve body (6) and the lower valve body (2). An annular right-angle groove is provided on the surface of the upper valve seat (18) opposite to the lower valve seat (4). The portion of the lower valve seat (4) opposite to the right-angle groove is convex outward to form a ring body with a right-angled triangle cross section. The surface where the right-angled side is located is connected to the lower valve seat (4), and the surface where the other right-angled side is located is the inner ring surface of the ring body, and the hypotenuse is stepped; the cross section of the sealing ring (19) is a right-angled trapezoid, and the surfaces where the lower base and the right-angled waist are located are respectively in contact with the two groove walls of the right-angled groove, and the hypotenuse waist is stepped and cooperates with the hypotenuse of the ring body, and the right angle between the upper base and the right-angled waist is in contact with the sealing portion (30); A guide rod (21) is provided at the small diameter end of the valve stem (17), the axis of the guide rod (21) coincides with the axis of the valve stem (17), one end of the guide rod (21) is connected to the valve stem (17), and the other end thereof passes through the valve body (25), and the guide rod (21) is sealed with the valve body (25) through a sealing component B.

2. The high-pressure stop valve for gas medium according to claim 1, characterized in that: A sealing cover (24) is connected to the portion of the valve body (25) through which the guide rod (21) passes, and the sealing cover (24) covers the guide rod (21).

3. The high-pressure stop valve for gas medium according to claim 1, characterized in that: The actuator is fixed to the valve body (25) through a connecting assembly, and the connecting assembly includes a support tube (11), a screw B (12) and a connecting plate (16). The connecting plate (16) is fixed to the valve body (25). One end of the support tube (11) is connected to the connecting plate (16), and the other end thereof is in contact with the outer shell of the actuator. The rod end of the screw B (12) passes through the center holes of the connecting plate (16) and the support tube (11) in turn, and is then threadedly connected to the outer shell of the actuator.

4. A high pressure stop valve for gas medium according to any one of claims 1 to 3, characterized in that: The actuator is a single-acting cylinder, and the large-diameter end of the valve stem (17) is connected to the end of the piston rod of the single-acting cylinder.

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