A new dual-channel gas source underpressure alarm device

Abstract

The present invention discloses a novel dual-path gas source underpressure alarm device, including a valve body, a valve core, an end cover, a spring, and a valve seat seal; a valve cavity is arranged inside the valve body; the middle of the valve cavity is a common cavity and is connected to an alarm-driven gas source output port; gas source inlets are arranged on both sides of the alarm-driven gas source output port; the spring is placed in the end cover and connected to the valve core, and the end cover controls the spring to drive the valve core to move outward or inward according to the air pressure; the valve seat seal is matched with the common cavity; when the valve core moves outward, the valve seat seal is closed, and the common cavity is in a closed state; when the valve core moves inward, the valve seat seal is opened, and the common cavity is in a connected state, and the alarm device alarms. This scheme adopts direct underpressure alarm to make up for the defects of false alarm and missed alarm of differential pressure alarm, and improves the reliability of the use of the device.

Description

Technical Field

[0001] The invention relates to the technical field of alarm devices, and in particular to a novel dual-path gas source underpressure alarm device. Background Art

[0002] In the field of medical respiratory anesthesia, gas mixers are often used, most of which are for mixing two gases. For example, air-oxygen mixers mix medical air and medical oxygen to produce mixed gases of different oxygen concentrations. In clinical use, mixed gases of different oxygen concentrations are adjusted according to the needs of patients for use by different hypoxic patients to avoid side effects such as oxygen poisoning caused by patients breathing high-concentration oxygen for a long time.

[0003] In order to improve the safety of the air-oxygen mixer, a safety alarm device needs to be installed on the air-oxygen mixer. When a single gas source fails, an alarm signal needs to be issued to prompt medical staff to deal with the gas source failure in time to prevent medical accidents.

[0004] Since mechanical valve adjustment is simple and intuitive, with high reliability and anti-electromagnetic interference, the air-oxygen mixers currently on the market are all pure mechanical valve adjustment air-oxygen mixers. Its alarm device uses the intake air source as power and uses a buzzer sound alarm, that is, a whistle or harmonica to sound an alarm.

[0005] Figure 1 It is a schematic diagram of the principle of the prior art. The two gases to be mixed are connected to the two inlets of the air-oxygen mixer from the air inlet after passing through the filter 402 and the anti-reverse valve 403. The two-way gas coupling voltage regulator module 407 is introduced, and the gas is stabilized by two stages of the two-way complementary voltage regulator module to make the pressure values ​​of the two gas outputs consistent. The gas with consistent pressure then enters the double cone proportional valve 409. The consistent pressure can ensure the accuracy of the gas mixing concentration, and then the gas is mixed according to the set gas concentration, and the mixed gas is output from the mixed gas outlet 408.

[0006] At the same time, at the air inlet of the air-oxygen mixer, two gas paths are introduced into the left and right inlets of the shuttle valve 406, and the outlet of the shuttle valve 406 is divided into two paths, one of which is connected to the buzzer alarm 404 through the throttle hole 405, and the other is connected to the outlet through the one-way valve.

[0007] In the prior art, the gas source failure alarm uses a shuttle valve pressure differential sensing alarm, that is, when the pressure difference between the two gas sources reaches the set value (or one gas supply is interrupted), the two differential pressures push the shuttle valve to open. Figure 2As shown, the shuttle valve is pushed to one side A. The higher pressure gas source B is output through the shuttle valve, and the shuttle valve output one way controls the flow rate through the throttle hole, driving the buzzer alarm C to alarm. Since the two-way gas coupling voltage regulator module throttles the high-pressure side gas source and outputs at the lower pressure of the two gas sources, when one way is cut off, the output pressure of the two-way gas coupling voltage regulator module is zero, which will cause the air-oxygen mixed output to be cut off. Therefore, the other way of the shuttle valve output directly supplies gas D to the output port through a one-way valve to prevent the situation of no output after the gas source is cut off.

[0008] In actual applications, respiratory anesthesia equipment has a minimum pressure requirement for the gas source pressure. Too low a gas source pressure will affect the normal function of the respiratory anesthesia equipment and bring risks to patients. Therefore, the relevant standards for respiratory anesthesia equipment also stipulate the minimum working pressure of the equipment gas source, and require that a gas source fault alarm signal should be issued when the gas source pressure is lower than the lower limit of the working pressure.

[0009] The air-oxygen mixer as a respiratory anesthesia device also has the same requirements. As mentioned above, the air mixers currently on the market use the pressure difference of the gas source to alarm due to technical reasons. When the pressure of both gas sources is low, if the pressure of one gas source is lower than the minimum working pressure, and the pressure difference of the two gas sources does not reach the set pressure difference, the pressure difference alarm device will miss the alarm and will not sound the alarm. Missing the alarm will bring greater risks of use. It does not fully meet the requirements of relevant standards.

[0010] On the other hand, when the pressure of both gas sources is higher than the minimum working pressure, but the pressure difference between the two gas sources exceeds the setting, the pressure difference alarm device will sound an alarm, while the air-oxygen mixer is still working normally. The pressure difference alarm device has a false alarm phenomenon, which interferes with the normal operation of the device.

[0011] The pressure differential alarm device of the prior art is as follows Figure 3 As shown. It mainly includes valve core 503, valve sleeve 505, spring 502, valve cover 201, and sealing ring 504. Valve core 503 is a sliding valve structure, and the middle position is longer. In normal operation, when the pressure on both sides is similar, spring 502 balances valve core 503 in the middle position, and the shuttle valve has no output. The one-way valve of the supplementary air supply port also prevents the gas from flowing back at the output port. The buzzer alarm device does not drive the air source and does not sound an alarm. When the pressure difference of the air sources on both sides reaches the set value, the valve core 503 is pushed to the side with low pressure, and the side with high pressure is connected to the outlet of the shuttle valve, and the buzzer device is driven to alarm through the throttle hole. And the air supply is supplemented to the outlet through the one-way valve. Limited by the structure of the air-oxygen mixer, the force acting area of ​​the valve core 503 is small, and it is a sliding valve structure, and there is also a problem of poor sensitivity.

[0012] In summary, the existing differential pressure alarm devices have defects such as missed alarms and false alarms, which may bring hidden dangers to safety and interfere with normal use.

[0013] It can be seen that how to overcome the problems of missed alarms and false alarms in the pressure differential alarm is a problem that needs to be solved in the art. Summary of the invention

[0014] In view of the technical problem of low reliability of existing gas source failure alarms, the purpose of the present invention is to provide a new dual-channel gas source underpressure alarm device, which can replace the existing pressure difference sensing method with an underpressure sensing method, thereby improving the stability of the alarm device and well solving the problems existing in the prior art.

[0015] In order to achieve the above-mentioned purpose, the present invention provides a novel dual-path gas source under-pressure alarm device, comprising a valve body, a valve core, an end cover, a spring, and a valve seat seal; a valve cavity is arranged inside the valve body; the middle of the valve cavity is a common cavity; an alarm driving gas source output port is arranged at the bottom of the common cavity; gas source inlets are symmetrically arranged on both sides of the alarm driving gas source output port; the internal components of the dual-path gas source under-pressure alarm device are symmetrically arranged with the common cavity as the symmetry line;

[0016] The end cover is arranged in the valve cavity and connected with the air source inlet, and air pressure is input into the end cover through the air source inlet; an air source outlet is arranged opposite to the air source inlet;

[0017] The spring is placed in the end cover and connected to the valve core. When the air pressure in the end cover overcomes the spring force, the valve core is driven to move outward; when the air pressure in the end cover is unbalanced with the spring force, the valve core is driven to move inward through the elastic recovery of the spring.

[0018] The valve seat seal is matched with the common cavity; when the valve core moves outward, the valve seat seal is closed and the common cavity is in a closed state, then the alarm driving air source output port has no air supply, and the air pressure is discharged through the air source output port; when the valve core moves inward, the valve seat seal is opened, and the common cavity is in a connected state, then the alarm driving air source output port has air output to drive the alarm device to alarm.

[0019] Furthermore, a fault supplementary air supply outlet is provided on the front side of the valve body and is connected to the common cavity, and air is supplied to the common cavity through the fault supplementary air supply outlet to restore the air pressure in the end cover;

[0020] Large shaped cavities are provided on both sides of the valve body and are connected with the air source inlet, and an intermediate cavity is provided between the large shaped cavities on both sides and the common shaped cavity; an air guide channel is provided on the inner end surface of the large shaped cavity; the air guide channel is connected with a transfer channel; the large shaped cavity is connected with the intermediate cavity through the air guide channel and the transfer channel.

[0021] Furthermore, the end cover is disc-shaped and is installed in the valve cavity by threaded connection; the middle of the inner side of the end cover is a central cavity and an annular cavity, and the outer side is a plane; the outer plane is provided with an air hole and communicates with the inner annular cavity.

[0022] Furthermore, the annular cavity is divided into an inner cavity and an outer cavity; the inner cavity and the outer cavity are isolated by a sealing component; the outer cavity is connected with an air hole and communicates with the outside.

[0023] Furthermore, the sealing assembly is composed of a first sealing member and a second sealing member; the first sealing member and the second sealing member are relatively arranged between the inner cavity and the outer cavity, and the inner cavity and the outer cavity are isolated by the first sealing member and the second sealing member.

[0024] Furthermore, the sealing assembly is a diaphragm seal; the diaphragm is placed between the inner cavity and the outer cavity, and the inner cavity and the outer cavity are isolated by the diaphragm seal.

[0025] Furthermore, the valve core is a rotating body; the large end of the valve core is a piston, and the small end is a piston rod;

[0026] The piston is placed in the annular cavity of the end cover, and a sealing ring groove is provided on the circumference of the piston; a first sealing member is provided on the sealing ring groove; the center of the piston end surface is a concave cavity; a sealing ring groove is provided in the concave cavity; a second sealing member is provided on the sealing ring groove in the concave cavity;

[0027] The piston rod is placed in the common cavity and the middle cavity, and a sealing ring groove is provided at the end of the piston rod; an end cover seal is provided on the sealing ring groove to separate the middle cavity from the large cavity; a balancing hole is provided at the center of the piston rod end surface and communicates with the concave cavity at the piston end.

[0028] The novel dual-path gas source underpressure alarm device provided by the present invention uses two sets of valve cores to independently drive gas source switches on opposite sides, thereby providing alarm gas sources for buzzer alarms, stabilizing alarm pressure, and improving the reliability of the alarm device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0030] Figure 1 It is a schematic diagram of the technical principle of the existing air-oxygen mixer;

[0031] Figure 2 It is a structural diagram of an existing alarm device;

[0032] Figure 3 It is a structural schematic diagram of an existing pressure differential alarm device;

[0033] Figure 4This is a cross-sectional view of the dual-path gas source underpressure alarm device;

[0034] Figure 5 This is a cross-sectional schematic diagram of the dual-path gas source underpressure alarm device;

[0035] Figure 6 This is a schematic diagram of the diaphragm structure of the dual-path gas source underpressure alarm device;

[0036] Figure 7 This is a schematic diagram of the under-pressure alarm state of the dual-channel gas source under-pressure alarm device;

[0037] Figure 8 This is a schematic diagram of the pressure balance at the end of the valve core of the dual-path gas source underpressure alarm device; DETAILED DESCRIPTION

[0038] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0039] This solution provides a novel dual-path gas source under-pressure alarm device, which integrates the dual-path gas source under-pressure alarm device into the air mixer valve body; adopts an independent double valve core structure, and balances the gas source pressure by the spring compression force to stabilize the alarm pressure.

[0040] See also Figure 4-Figure 5 The dual-path gas source underpressure alarm device comprises a valve body 1, a valve core 2a, an end cover 3a, a spring 4a, a valve seat seal 5a, a piston rod seal 6a, an end cover seal 7a, a piston seal 8a and a piston inner seal 9a.

[0041] The valve body 1 is a block that can be integrated with the air-oxygen mixer valve body, and is provided with a valve cavity 100 in the middle of the valve body. The valve cavity 100 is a symmetrical multi-step cavity, and the middle of the multi-step cavity is a common cavity 107. An alarm driving gas source output port 131 is provided at the bottom of the common cavity 107 for connecting an alarm device. A fault supplementary gas supply outlet 132 is also provided on the front side of the valve body 1 and is connected to the common cavity 107. The fault supplementary gas supply outlet 132 is used to replenish gas to the common cavity 107 to restore the air pressure.

[0042] Among them, the dual-circuit pressure underpressure alarm device is centrally symmetrically arranged with the common cavity 107 as the symmetry line, and is divided into left and right sides. The setting structures of the symmetrical sides are the same, and the left side is now taken as an example for explanation.

[0043] An air source inlet 111 is provided on the side of the alarm driving air source output port 131 ; and an air source output port 121 is provided corresponding to the air source inlet 111 .

[0044] An open large-shaped cavity 101 is provided on one side of the common-shaped cavity 107, and an air source air inlet 111 is communicated with the corresponding outer large-shaped cavity 101 through a circular circumference and is communicated with the corresponding air source outlet 121 at the top; an internal threaded hole 103 is provided at the outer end of the large-shaped cavity 101; an intermediate cavity 105 is provided between the common-shaped cavity 107 and the large-shaped cavity 101, and a sealing ring groove is provided between the common-shaped cavity 107 and the intermediate cavity 105.

[0045] An air guide channel 123 is provided on the inner end surface of the large cavity 101 ; 123 is connected to a switching channel 125 ; the large cavity 101 is connected to the middle cavity 105 through the air guide channel 123 and the switching channel 125 .

[0046] The valve seat seal 5a is arranged on the valve core 2a; when the valve core 2a moves outward, it drives the valve seat seal 5a to cooperate with the sealing ring groove between the common cavity 107 and the intermediate cavity 105, and the common cavity 107 is in a closed state at this time, and the air pressure is discharged through the air source output port 121; when the valve core 2a moves inward, the valve seat seal 5a is opened, and the common cavity 107 is in a connected state.

[0047] The end cap 3a is disc-shaped and is threadedly connected to the inner threaded hole on the outside of the large cavity 101; the center of the inner side of the end cap 3a is respectively a central cavity 310 and an annular cavity 320; the annular cavity 320 is divided into an inner cavity 231 and an outer cavity 232, and the inner cavity and the outer cavity are not connected; the outer cavity 232 is connected to a vent hole 321 and communicates with the outside

[0048] The outer side is a plane; the inner side of the outer edge of the end cover 3a is a cylindrical surface 322, on which a sealing ring groove is provided for mounting the end cover seal 7a, and the outer side is a thread 323.

[0049] The shape of the end cover seal 7a is not limited, and an O-shaped rubber seal may be selected, and the size of the O-shaped rubber seal is consistent with the size of the sealing ring groove on the cylindrical surface of the end cover.

[0050] The valve core 2a is a rotating body, which is inserted into the corresponding cavity of the valve cavity 100. The large end of the valve core 2a is a piston 230, and the small end is a piston rod 240.

[0051] The piston 230 is placed in the annular cavity 320 of the end cover 3a, and has a sealing ring groove 211 on the circumference for installing the piston seal 8a; the center of the end surface of the piston 230 is a concave cavity 212; the concave cavity 212 is provided with a sealing ring groove 213 for installing the piston inner seal 9a;

[0052] The shapes of the piston seal 8a and the piston inner seal 9a are not limited, and O-shaped rubber seals can be selected. The sizes of the O-shaped rubber seals are respectively consistent with the sealing ring groove 211 on the circumference of the piston and the sealing ring groove 213 in the concave cavity.

[0053] The piston rod 240 is arranged in the common cavity 107 and the corresponding intermediate cavity 105; the end of the piston rod 240 is a sealing ring groove 221 for installing the piston rod seal 6a and isolating the intermediate cavity 105 from the large cavity 101 by sealing.

[0054] The shape of the piston rod seal 6a is not limited, and an O-shaped rubber seal may be selected, and the size of the O-shaped rubber seal is consistent with the sealing ring groove 221 on the end of the piston rod 240.

[0055] The valve core 2a is also provided with a gas pressure thrust for resetting the valve core. The gas pressure thrust is achieved by providing a balancing hole 242 and a concave cavity 252 on the valve core 2a, and the area of ​​the concave cavity 252 is consistent with the area of ​​the valve seat seal 5a at the end of the valve core piston rod. The valve core 2a, the balancing hole 242 and the concave cavity 252 are connected in sequence and connected to the outside world, thereby balancing the gas pressure thrust on the end face of the valve core piston rod 240.

[0056] The end cover seal 7a, the piston seal 8a and the piston inner seal 9a isolate the inner cavity 231 and the outer cavity 232 of the piston by sealing.

[0057] See also Figure 6 The technical solution for isolating the inner cavity 231 from the outer cavity 232 is not limited here, and a diaphragm seal 10 may be placed between the inner cavity 231 and the outer cavity 232 to isolate the inner cavity 231 from the outer cavity 232.

[0058] The spring 4a is a conventional cylindrical spring, which is placed in the central cavity 310 of the end cover and connected to the concave cavity 252 of the valve core. When the end cover 3a is installed in the internal threaded hole 103 outside the valve cavity, the spring 4a is compressed.

[0059] Air pressure is input into the end cover 3a through the air source input port 111; when the air pressure in the end cover 3a overcomes the spring force, the valve core 2a is driven to move outward; when the air pressure in the end cover 3a is unbalanced with the spring force, the valve core 2a is driven to move inward through the elastic recovery of the spring.

[0060] The right device includes a valve core 2b, an end cover 3b, a spring 4b, a valve seat seal 5b, a piston rod seal 6b, an end cover seal 7b, a piston seal 8b and a piston inner seal 9b, an air source inlet 112, an air source outlet 122, a large cavity 102, an internal threaded hole 104, an intermediate cavity 106, an air guide channel 124, a transfer channel 126, a central cavity 330, an annular cavity 340, an inner cavity 233, an outer cavity 234, an air vent 324, a piston 210, a piston rod 220, a balance hole 222, and a concave cavity 212; the components inside the right side have the same structural arrangement as the above-mentioned left side components, and will not be repeated here.

[0061] The following example illustrates its working process in a specific application:

[0062] When in use, the structures on both sides of the device perform the same operation process. The following example illustrates the operation process of the left structure:

[0063] The alarm driving gas source output port 131 is connected to the throttle hole and the buzzer alarm device, and the gas source outlet 121 is connected to the dual-channel gas source coupling voltage stabilizing module of the air-oxygen mixer; the supplementary gas supply outlet is connected to the one-way valve and connected to the air-oxygen mixed gas output port.

[0064] During operation, the air source inlet 111 is connected to the working air source, and the air source passes through the inner cavity 231 of the piston in the valve body 1, and then communicates with the air vent 321 through the outer cavity 232 of the piston.

[0065] At this time, air pressure is continuously delivered to the inner cavity 231 of the piston through the air source inlet 111. When the air pressure overcomes the compression force of the spring 4a, the valve core 2a is driven to move outward at the same time until the valve seat seal 5a is closed, thereby isolating the common cavity 107 and the intermediate cavity 105.

[0066] The common cavity 107 is not connected to the gas source delivered, and the one-way valve behind the supplementary gas supply port 132 blocks the gas source of the air-oxygen mixing output port. At this time, the alarm driving gas source output port 131 connected to the common cavity 107 does not alarm because the valve seat seal 5a is closed and the one-way valve is blocked and there is no gas source supply.

[0067] The delivered gas source is respectively passed from the gas source outlet 121 to the dual-path gas coupling pressure stabilizing module of the air-oxygen mixer, and enters the air-oxygen mixer for operation.

[0068] See also Figure 7 When the air source on this side is under-pressured and the pressure is less than the set minimum working pressure, the air source pressure in the inner cavity 231 of the piston is insufficient to balance the spring force set by the spring 4a. At this time, the elastic recovery of the spring 4a will push the valve core 2a to move inward, so that the valve seat seal 5a opens, and the air source passes through the air guide channel 123 and the transfer channel 125, enters the side middle cavity 105, enters the common cavity 107, and then outputs from the alarm drive air source output port 131, and drives the buzzer alarm after passing through the throttle hole. The air supply outlet 132 is used to supplement the air supply to the air-oxygen mixing outlet to prevent the output from being cut off.

[0069] When the pressure on the side with underpressure of the gas source is restored, the valve core on this side is reset by the gas source pressure, the valve seat seal is closed, and the alarm is turned off.

[0070] See also Figure 8In addition, when the underpressure alarm is turned on, the common chamber pressure 107 rises, and the end of the valve core's piston rod 240 will be affected by the common chamber pressure 107. The balance hole 242 and the concave cavity 252 on the valve core 2a will discharge the pressure, balancing the air pressure thrust on the end face of the valve core piston rod 240 and eliminating the influence of the common chamber pressure 107 on the alarm pressure.

[0071] Similarly, when the right side gas source is under-pressure, the working principle is the same as that of the left side mentioned above, and will not be elaborated here.

[0072] The novel dual-channel gas source underpressure alarm device formed by the above scheme adopts direct underpressure alarm to improve the safety of use, make up for the defects of false alarm and missed alarm of differential pressure alarm, improve the safety and reliability of the device, and reduce the risk of device use.

[0073] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A new dual-channel gas source underpressure alarm device, characterized in that: It includes a valve body, a valve core, an end cover, a spring, and a valve seat seal; a valve cavity is arranged inside the valve body; the middle of the valve cavity is a common cavity; an alarm driving air source output port is arranged at the bottom of the common cavity; air source inlets are symmetrically arranged on both sides of the alarm driving air source output port; the internal components of the dual-path air source underpressure alarm device are symmetrically arranged with the common cavity as the symmetry line; The end cover is arranged in the valve cavity and connected with the air source inlet, and the air pressure is input into the end cover through the air source inlet; the air source outlet is arranged opposite to the air source inlet; the end cover is disc-shaped and is connected and installed in the valve cavity by threading; the middle of the inner side of the end cover is respectively a central cavity and an annular cavity, and the outer side is a plane; the plane is provided with an air hole and is connected with the inner annular cavity; The spring is placed in the end cover and connected to the valve core. When the air pressure in the end cover overcomes the spring force, the valve core is driven to move outward. When the air pressure in the end cover is unbalanced with the spring force, the valve core is driven to move inward through the elastic recovery of the spring. The valve seat seal is matched with the common cavity; when the valve core moves outward, the valve seat seal is closed, and the common cavity is in a closed state, then the alarm driving air source output port has no air supply, and the air pressure is discharged through the air source output port; when the valve core moves inward, the valve seat seal is opened, and the common cavity is in a connected state, then the alarm driving air source output port has air output to drive the alarm device to alarm; The front side of the valve body is provided with a fault supplementary air supply outlet and is connected to the common cavity, and air is supplied to the common cavity through the fault supplementary air supply outlet to restore the air pressure in the end cover; Large shaped cavities are provided on both sides of the valve body and are connected with the air source inlet, and an intermediate cavity is provided between the large shaped cavities on both sides and the common shaped cavity; an air guide channel is provided on the inner end surface of the large shaped cavity; the air guide channel is connected with a transfer channel; the large shaped cavity is connected with the intermediate cavity through the air guide channel and the transfer channel.

2. A novel dual-channel gas source underpressure alarm device according to claim 1, characterized in that: The annular cavity is divided into an inner cavity and an outer cavity; the inner cavity and the outer cavity are isolated by a sealing component; the outer cavity is connected with an air hole and communicates with the outside.

3. A novel dual-channel gas source underpressure alarm device according to claim 2, characterized in that: The sealing assembly is composed of a first sealing member and a second sealing member; the first sealing member and the second sealing member are relatively arranged between the inner cavity and the outer cavity, and the inner cavity and the outer cavity are isolated by the first sealing member and the second sealing member.

4. A novel dual-channel gas source underpressure alarm device according to claim 2, characterized in that: The sealing component is a diaphragm seal; the diaphragm is placed between the inner cavity and the outer cavity, and the inner cavity and the outer cavity are isolated by the diaphragm seal.

5. A novel dual-channel gas source underpressure alarm device according to claim 1, characterized in that: The valve core is a rotating body; the large end of the valve core is a piston, and the small end is a piston rod; The piston is placed in the annular cavity of the end cover, and a sealing ring groove is provided on the circumference of the piston; a first sealing member is provided on the sealing ring groove; the center of the piston end surface is a concave cavity; a sealing ring groove is provided in the concave cavity; a second sealing member is provided on the sealing ring groove in the concave cavity; The piston rod is placed in the common cavity and the middle cavity, and a sealing ring groove is provided at the end of the piston rod; an end cover seal is provided on the sealing ring groove to separate the middle cavity from the large cavity; a balancing hole is provided at the center of the piston rod end surface and communicates with the concave cavity at the piston end.

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