Multi-stage adjustable slow closing mute oil cylinder for valve

Abstract

The application relates to the technical field of valve oil cylinders and discloses a multistage adjustable slow-closing mute oil cylinder for a valve, which comprises a cylinder body, a piston cylinder and a piston, the piston is connected to the output end of a transmission mechanism, the piston cylinder is arranged in the cylinder body, the piston is arranged in the piston cylinder, the piston cylinder divides the inner cavity of the cylinder body into a first oil inlet cavity and a first oil return cavity, and the piston divides the inner cavity of the piston cylinder into a second oil inlet cavity and a second oil return cavity; A oil port, B oil port and C oil port are arranged on the cylinder body, the C oil port is communicated with the first oil inlet cavity, the A oil port and the B oil port are both communicated with the first oil return cavity; the A oil port and the C oil port are communicated through an oil pipe, and a first throttle valve is arranged on the oil pipe; the application can solve the technical problem of buffer control of a large-angle valve and can realize buffer control of the large-angle valve.

Description

Technical Field

[0001] This invention relates to the field of valve cylinders, and more specifically, to a multi-stage adjustable slow-closing silent valve cylinder. Background Technology

[0002] Chinese patent CN214037072U discloses a multi-stage adjustable slow-closing silent hydraulic cylinder for valves that uses a single-stage hydraulic cylinder. This multi-stage adjustable slow-closing silent hydraulic cylinder for valves has a piston on the cylinder body, with the piston rod and sealing ring located inside the piston. One-way throttle valves I and II are connected to the cylinder body through oil pipes. By converting the rotary motion of the valve into the linear rapid motion of the hydraulic cylinder, the damping force generated by the hydraulic cylinder is converted into valve closing resistance by the pin shaft, realizing multi-stage slow closing of the valve and eliminating water hammer. However, it uses a single-stage hydraulic cylinder, which cannot meet the buffer control of valves with large angles. Summary of the Invention

[0003] This invention provides a multi-stage adjustable slow-closing silent hydraulic cylinder for valves, solving the technical problem that related technologies cannot meet the buffer control requirements of valves with large angles, and enabling buffer control of valves with large angles.

[0004] At least one embodiment of the present invention discloses a multi-stage adjustable slow-closing silent hydraulic cylinder for valves, including a cylinder body, a piston cylinder, a piston, and a transmission mechanism. The transmission mechanism is connected to a rotating shaft that controls the opening and closing of the valve. The piston is connected to the output end of the transmission mechanism. The piston cylinder is sleeved in the cylinder body, and the piston is sleeved in the piston cylinder. The piston cylinder divides the inner cavity of the cylinder body into a first oil inlet chamber and a first oil return chamber, and the piston divides the inner cavity of the piston cylinder into a second oil inlet chamber and a second oil return chamber.

[0005] The cylinder block is provided with oil port A, oil port B and oil port C. Oil port C is connected to the first oil inlet chamber, and oil ports A and B are both connected to the first oil return chamber.

[0006] Oil port A and oil port C are connected by an oil pipe, on which a first throttle valve is installed;

[0007] Oil port B and oil port C are connected by an oil pipe, on which a second throttle valve is installed;

[0008] Oil port B is located to the right of oil port A; the piston cylinder is provided with a cylindrical section that contacts the inner wall of the cylinder body, and the distance between oil port A and oil port B is less than the length of the cylindrical section.

[0009] The piston cylinder is provided with oil port D and oil port E. Oil port D is connected to the first oil inlet chamber and the second oil inlet chamber, and oil port E is connected to the first oil return chamber and the second oil return chamber.

[0010] First stage: The piston retracts into the piston cylinder, and the hydraulic oil in the second return oil chamber enters the first return oil chamber. The hydraulic oil in the first return oil chamber is discharged to the C port through the A and B ports, enters the first inlet oil chamber from the C port, and then enters the second inlet oil chamber from the first inlet oil chamber. At this time, the first throttle valve and the second throttle valve jointly limit the flow and generate damping.

[0011] Second stage: After the piston is fully retracted into the piston cylinder, the piston cylinder retracts into the cylinder body. The hydraulic oil in the first return oil chamber is discharged through port A and port B to port C, and then enters the first inlet oil chamber from port C. At this time, the first throttle valve and the second throttle valve jointly limit the flow and generate damping. In this stage, the cross-sectional area of ​​the first return oil chamber is larger than that of the second return oil chamber. Therefore, the hydraulic pressure generated by the same throttle valve action on the piston cylinder is greater than the pressure acting on the piston, and the resistance of the valve is greater than in the first stage.

[0012] Third stage: The piston cylinder retracts into the cylinder body to close port B. The hydraulic oil in the first return oil chamber is discharged through port A to port C and enters the first inlet oil chamber from port C. At this time, the first throttle valve limits the flow and generates damping. At this time, the equivalent cross-sectional area of ​​the hydraulic oil circulation channel is reduced, and the resistance of the valve is greater than that in the second stage.

[0013] In at least one embodiment of the present invention, it is disclosed that the distance between oil port A and oil port B is smaller than the distance between oil port B and oil port C.

[0014] In at least one embodiment of the present invention, it is disclosed that both the first throttle valve and the second throttle valve are one-way throttle valves.

[0015] At least one embodiment of the present invention discloses that the transmission mechanism includes a crank arm, one end of which is fixedly connected to a rotating shaft that controls the opening and closing of the valve, and the other end of which is provided with a slide groove. A pin is slidably connected inside the slide groove, one end of which is fixedly connected to a connecting shaft, and one end of which is fixedly connected to a piston. When the valve is closed, the force is transmitted to the pin through the crank arm, and the pin converts the torque generated by the rotation of the valve into a force in a linear direction.

[0016] In at least one embodiment of the present invention, it is disclosed that the B oil port is a strip-shaped hole, the length of which is less than 2 / 3 of the length of the cylindrical section of the piston cylinder, and the distance between its right end and the inner wall of the left end of the cylinder body is less than the length of the cylindrical section of the piston cylinder.

[0017] In at least one embodiment of the present invention, it is disclosed that the flow rate of the second throttle valve is greater than the flow rate of the first throttle valve.

[0018] At least one embodiment of the present invention discloses a control method for a multi-stage adjustable slow-closing silent hydraulic cylinder for valves, comprising the following steps:

[0019] Step S101: Sample the valve's associated information at fixed time intervals;

[0020] Step S102: Generate time-series data based on the collected correlation information. The time-series data is represented as follows:

[0021] {δ1, δ2, ..., δ t},in Let represent the temperature of the medium passing through the valve, the pressure of the medium passing through the valve, the density of the medium passing through the valve, the valve opening degree, and the flow rate through the valve at time t, respectively.

[0022] Step S103: Input the time series data into the parameter generation model. The parameter generation model includes a first hidden layer and two fully connected layers. The calculation formula for the first hidden layer is as follows:

[0023] R (0) =δ1

[0024] i (t) =σ(W ii δ t +W ri R (t-1) +b ri )

[0025] f (t) =σ(W if δ t +W rf R (t-1) +b rf )

[0026] g (t) =tanh(W ig δ t +W rg R (t-1) +b rg )

[0027] o (t) =σ(W io δ t +W ro R (t-1) +b ro )

[0028] v (t) =f (t) *v (t-1) +i (t) *g (t)

[0029] R (t) =o (t) ⊙tanh(v (t) )

[0030] Where R(t) represents the output feature at time step t, R (t-1) W represents the output feature at time step (t-1); ⊙ represents the dot product. ii W if W ig W io W ri W rf W rg W ro b represents the weight parameter. ri b rf b rg b ro Indicates the bias parameter;

[0031] The output features of the last time step of the first hidden layer are input into two fully connected layers, and the two fully connected layers output the values ​​of the flow parameters of the first and second throttle valves, respectively.

[0032] Step S104: Control the first throttle valve based on the flow parameters of the first throttle valve generated by the parameter generation model, and control the second throttle valve based on the flow parameters of the second throttle valve generated by the parameter generation model.

[0033] In at least one embodiment of the present invention, steps S101-S104 are executed cyclically according to an execution time interval, wherein the execution time interval is greater than the sampling time interval.

[0034] At least one embodiment of the present invention discloses that the associated information for each sampling includes information about the medium passing through the valve and the valve parameters;

[0035] Valve parameters include valve opening degree and flow rate through the valve.

[0036] The beneficial effects of this invention are as follows:

[0037] It can provide buffer control for valves with large angles, and the dynamic control of the flow rate through the throttle valve can eliminate water hammer while improving the valve's response speed. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the first stage state of the present invention;

[0039] Figure 2 This is a schematic diagram of the second stage state of the present invention;

[0040] Figure 3 This is a schematic diagram of the third stage state of the present invention;

[0041] Figure 4 This is a schematic diagram of the transmission mechanism of the present invention in its transmission state;

[0042] Figure 5 This is a schematic diagram of the B oil port of the present invention being a strip-shaped hole.

[0043] Figure 6 This is a flowchart of a control method for a multi-stage adjustable slow-closing silent hydraulic cylinder for valves according to the present invention.

[0044] In the diagram: 001, Rotary shaft; 1, Cylinder body; 11, First oil inlet chamber; 12, First oil return chamber; 2, Piston cylinder; 21, Second oil inlet chamber; 22, Second oil return chamber; 3, Piston; 4, Oil port A; 5, Oil port B; 6, Oil port C; 7, Oil pipe; 8, First throttle valve; 9, Second throttle valve; 100, Oil port D; 110, Oil port E; 200, Transmission mechanism; 201, Crank arm; 202, Slide groove; 203, Pin; 204, Connecting shaft. Detailed Implementation

[0045] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0046] like Figures 1-4 As shown, a multi-stage adjustable slow-closing silent hydraulic cylinder for valves includes a transmission mechanism 200. The input end of the transmission mechanism 200 is connected to the valve, and the torque generated when the valve rotates is converted into a force in a straight line for output.

[0047] It also includes a cylinder body 1, a piston cylinder 2 and a piston 3. The piston 3 is connected to the output end of the transmission mechanism 200. The piston cylinder 2 is sleeved inside the cylinder body 1 and the piston 3 is sleeved inside the piston cylinder 2. The piston cylinder 2 divides the inner cavity of the cylinder body 1 into a first oil inlet chamber 11 and a first oil return chamber 12. The piston 3 divides the inner cavity of the piston cylinder 2 into a second oil inlet chamber 21 and a second oil return chamber 22.

[0048] The cylinder body 1 is provided with oil port A 4, oil port B 5 and oil port C 6. Oil port C 6 is connected to the first oil inlet chamber 11, and oil port A 4 and oil port B 5 are both connected to the first oil return chamber 12.

[0049] Oil port 4 and oil port 6 are connected by oil pipe 7, on which a first throttle valve 8 is installed.

[0050] Oil port 5 (B) and oil port 6 (C) are connected by oil pipe 7, on which a second throttle valve 9 is installed.

[0051] Oil port 5 is located to the right of oil port 4; the piston cylinder 2 is provided with a cylindrical section that contacts the inner wall of the cylinder body 1, and the distance (D1) between oil port 4 and oil port 5 is less than the length (D2) of the cylindrical section.

[0052] The piston cylinder 2 is provided with oil port D 100 and oil port E 110. Oil port D 100 is connected to the first oil inlet chamber 11 and the second oil inlet chamber 21, and oil port E 110 is connected to the first oil return chamber 12 and the second oil return chamber 22.

[0053] First stage: Piston 3 retracts into piston cylinder 2, hydraulic oil in the second return oil chamber 22 enters the first return oil chamber 12, hydraulic oil in the first return oil chamber 12 is discharged to C port 6 through A port 4 and B port 5, enters the first inlet oil chamber 11 from C port 6, and then enters the second inlet oil chamber 21 from the first inlet oil chamber 11. At this time, the first throttle valve 8 and the second throttle valve 9 together limit the flow and generate damping.

[0054] Second stage: After piston 3 is fully retracted into piston cylinder 2, piston cylinder 2 retracts into cylinder body 1. The hydraulic oil in the first return oil chamber 12 is discharged to port C 6 through port A 4 and port B 5, and enters the first inlet oil chamber 11 from port C 6. At this time, the first throttle valve 8 and the second throttle valve 9 jointly limit the flow and generate damping. In this stage, the cross-sectional area of ​​the first return oil chamber 12 is larger than the cross-sectional area of ​​the second return oil chamber 22. Therefore, the hydraulic pressure generated by the same throttle valve acting on piston cylinder 2 is greater than the pressure acting on piston 3, and the resistance of the valve is greater than in the first stage.

[0055] Third stage: Piston cylinder 2 retracts into cylinder body 1 to close oil port 5 by B. Hydraulic oil in the first return oil chamber 12 is discharged through oil port 4 to oil port 6 and enters the first inlet oil chamber 11 from oil port 6. At this time, the first throttle valve 8 limits the flow and generates damping. At this time, the equivalent cross-sectional area of ​​the hydraulic oil circulation channel is reduced, and the resistance of the valve is greater than that in the second stage.

[0056] The above embodiments enable a three-stage gradual buffering mechanism for large-angle valves, effectively reducing noise.

[0057] The first oil inlet chamber 11, the first oil return chamber 12, oil port A 4, oil port B 5, oil port C 6, oil pipe 7, the first throttle valve 8, the second throttle valve 9, oil port D 100, oil port E 110, the second oil inlet chamber 21, and the second oil return chamber 22 together form the hydraulic oil circulation channel.

[0058] In one embodiment of this disclosure, the transmission mechanism 200 includes a crank arm 201. One end of the crank arm 201 is fixedly connected to a rotating shaft 001 that controls the opening and closing of the valve. The other end of the crank arm 201 is provided with a slide groove 202. A pin 203 is slidably connected inside the slide groove 202. A connecting shaft 204 is fixedly connected to one end of the pin 203. One end of the connecting shaft 204 is fixedly connected to the piston 3. When the valve is closed, the force is transmitted to the pin 203 through the crank arm 201. The pin 203 converts the torque generated by the rotation of the valve into a force in the linear direction.

[0059] In one embodiment of this disclosure, the distance between oil port 4 (A) and oil port 5 (B) is smaller than the distance between oil port 5 (B) and oil port 6 (C).

[0060] In one embodiment of this disclosure, the first throttle valve 8 and the second throttle valve 9 are both one-way throttle valves, which restrict the flow of hydraulic oil from port A 4 and port B 5 to port C 6, but do not restrict the flow of hydraulic oil from port C 6 to port A 4 and port B 5. The first throttle valve 8 and the second throttle valve 9 include, but are not limited to, one-way throttle valves of model STU-G1.

[0061] like Figure 5 As shown, in one embodiment of this disclosure, oil port 5 is a strip-shaped hole with a length (D3) less than 2 / 3 of the length (D2) of the cylindrical section of piston cylinder 2, and the distance (D4) between its right end and the inner wall of the left end of cylinder body 1 is less than the length (D2) of the cylindrical section of piston cylinder 2.

[0062] The diameter of the B port 5 of the strip-shaped orifice gradually decreases during the movement of the piston cylinder 2, thus gradually increasing the flow resistance.

[0063] In one embodiment of this disclosure, the flow rate of the second throttle valve 9 is greater than the flow rate of the first throttle valve 8.

[0064] In the foregoing embodiments of this disclosure, a multi-stage buffer cylinder structure is provided, which uses a throttle valve for throttling. The throttle valve needs to adjust the flow parameters for control, and generally a fixed flow parameter is set based on empirical values.

[0065] For the operating environment of chemical plants, due to the high activity and complex properties of the media, the water hammer effect has a greater impact on the pipeline transportation system. Fixed flow parameters cannot adapt to complex media conditions. Fixed flow parameters are set to be relatively small, but this results in a slow speed of valve-to-pipeline flow control, which may have a negative impact on some process links.

[0066] To address the aforementioned problems, one embodiment of the present invention provides a control method for a multi-stage adjustable slow-closing silent hydraulic cylinder for valves, such as... Figure 6 As shown, it includes the following steps:

[0067] Step S101: Sample the valve's associated information at fixed time intervals;

[0068] The associated information for each sample includes the medium passing through the valve and the valve parameters;

[0069] Valve parameters include valve opening degree and flow rate through the valve;

[0070] Step S102: Generate time-series data based on the collected correlation information. The time-series data is represented as follows:

[0071] {δ1, δ2, ..., δ t},in Let represent the temperature of the medium passing through the valve, the pressure of the medium passing through the valve, the density of the medium passing through the valve, the valve opening degree, and the flow rate through the valve at time t, respectively.

[0072] Step S103: Input the time series data into the parameter generation model. The parameter generation model includes a first hidden layer and two fully connected layers. The calculation formula for the first hidden layer is as follows:

[0073] R (0) =δ1

[0074] i (t) =σ(W ii δ t +W ri R (t-1) +b ri )

[0075] f (t) =σ(W if δ t +W rf R (t-1) +b rf )

[0076] g (t) =tanh(W ig δ t +W rg R (t-1) +b rg )

[0077] o (t) =σ(W io δ t +W ro R (t-1) +b ro )

[0078] v (t) =f (t) *v (t-1) +i (t) *g(t)

[0079] R (t) =o (t) ⊙tanh(v (t) )

[0080] Where R(t) represents the output feature at time step t, R (t-1) W represents the output feature at time step (t-1); ⊙ represents the dot product. ii v if W ig v io W ri W rf W rg W ro b represents the weight parameter. ri b rf b rg b ro This represents the bias parameter.

[0081] The output features of the last time step of the first hidden layer are input into two fully connected layers, and the two fully connected layers output the values ​​of the flow parameters of the first throttle valve 8 and the second throttle valve 9, respectively.

[0082] Step S104: Control the first throttle valve 8 based on the flow parameters of the first throttle valve 8 generated by the parameter generation model, and control the second throttle valve 9 based on the flow parameters of the second throttle valve 9 generated by the parameter generation model.

[0083] The control process of the first throttle valve 8 and the second throttle valve 9 is carried out according to a fixed time, that is, steps S101-S104 are executed cyclically according to the execution time interval, which is greater than the sampling time interval.

[0084] Steps S101-S104 are performed during the valve adjustment process.

[0085] Since the parameters of throttle valves are different, the flow adjustment range is also different. In order to standardize the meaning of the parameters, the flow parameters of throttle valves are limited by per-unit values, for example, 1pu = 10 cubic meters / second.

[0086] For the aforementioned parameter generation model, if it is extracted from historical data, a significant amount of manual labor is required to screen training samples that meet the criteria.

[0087] One embodiment of this invention provides another method for obtaining training samples. First, a simulation system based on a pipeline transportation system is constructed. Parameters are extracted from historical data to simulate the valve operating environment. The flow parameters of different throttle valves are continuously adjusted. Then, a set of flow parameters (the flow parameters of the throttle valves) with the fastest valve response and a water hammer effect less than a set value is obtained as the true values ​​of the training samples. In this way, representative training samples can be extracted from historical data, and then the optimal flow parameters are obtained through simulation to obtain the true values ​​corresponding to the training samples. The valve response speed can be calculated as the average speed within the sampling time interval, and the unit of response speed can be ΔL / s, where ΔL is the change in valve flow rate within the sampling time interval.

[0088] The aforementioned control method using a multi-stage adjustable slow-closing silent hydraulic cylinder for valves can maximize the valve's response speed while ensuring that the water hammer effect is less than a set value. The effect value can be quantified as the impact force on the valve core.

[0089] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A multi-stage adjustable slow-closing silent hydraulic cylinder for a valve, characterized in that, The system includes a cylinder body (1), a piston cylinder (2), a piston (3), and a transmission mechanism (200). The transmission mechanism (200) is connected to a rotating shaft (001) that controls the opening and closing of the valve. The piston (3) is connected to the output end of the transmission mechanism (200). The piston cylinder (2) is fitted inside the cylinder body (1), and the piston (3) is fitted inside the piston cylinder (2). The piston cylinder (2) divides the inner cavity of the cylinder body (1) into a first oil inlet chamber (11) and a first oil return chamber (12). The piston (3) divides the inner cavity of the piston cylinder (2) into a second oil inlet chamber (21) and a second oil return chamber (22). The cylinder body (1) is provided with oil port A (4), oil port B (5) and oil port C (6). Oil port C (6) is connected to the first oil inlet chamber (11). Oil port A (4) and oil port B (5) are both connected to the first oil return chamber (12). Oil port A (4) and oil port C (6) are connected by oil pipe (7), and a first throttle valve (8) is installed on the oil pipe (7). Oil port B (5) and oil port C (6) are connected by oil pipe (7), and a second throttle valve (9) is installed on the oil pipe (7). Oil port B (5) is located to the right of oil port A (4); the piston cylinder (2) is provided with a cylindrical section that contacts the inner wall of the cylinder body (1), and the distance between oil port A (4) and oil port B (5) is less than the length of the cylindrical section; The piston cylinder (2) is provided with oil port D (100) and oil port E (110). Oil port D (100) is connected to the first oil inlet chamber (11) and the second oil inlet chamber (21). Oil port E (110) is connected to the first oil return chamber (12) and the second oil return chamber (22).

2. The multi-stage adjustable slow-closing silent hydraulic cylinder for valves according to claim 1, characterized in that, First stage: The piston (3) retracts into the piston cylinder (2), and the hydraulic oil in the second return oil chamber (22) enters the first return oil chamber (12). The hydraulic oil in the first return oil chamber (12) is discharged to the C oil port (6) through the A oil port (4) and the B oil port (5). It enters the first oil inlet chamber (11) from the C oil port (6) and then enters the second oil inlet chamber (21) from the first oil inlet chamber (11). At this time, the first throttle valve (8) and the second throttle valve (9) jointly limit the flow and generate damping. Second stage: After the piston (3) is fully retracted into the piston cylinder (2), the piston cylinder (2) retracts into the cylinder body (1), and the hydraulic oil in the first return oil chamber (12) is discharged to the C oil port (6) through the A oil port (4) and the B oil port (5), and enters the first inlet oil chamber (11) from the C oil port (6); at this time, the first throttle valve (8) and the second throttle valve (9) jointly limit the flow and generate damping; in this stage, the cross-sectional area of ​​the first return oil chamber (12) is larger than the cross-sectional area of ​​the second return oil chamber (22), so the hydraulic pressure generated by the same throttle valve action on the piston cylinder (2) is greater than the pressure on the piston (3), and the resistance of the valve is greater than in the first stage; Third stage: The piston cylinder (2) retracts into the cylinder body (1) to close the B oil port (5), and the hydraulic oil in the first return oil chamber (12) is discharged through the A oil port (4) to the C oil port (6), and enters the first inlet oil chamber (11) from the C oil port (6); at this time, the first throttle valve (8) limits the flow and generates damping. At this time, the equivalent cross-sectional area of ​​the hydraulic oil circulation channel is reduced, and the resistance of the valve is greater than that in the second stage.

3. A multi-stage adjustable slow-closing silent hydraulic cylinder for valves according to claim 1, characterized in that, The distance between oil port A (4) and oil port B (5) is less than the distance between oil port B (5) and oil port C (6).

4. A multi-stage adjustable slow-closing silent hydraulic cylinder for valves according to claim 1, characterized in that, Both the first throttle valve (8) and the second throttle valve (9) are one-way throttle valves.

5. A multi-stage adjustable slow-closing silent hydraulic cylinder for valves according to claim 1, characterized in that, The transmission mechanism (200) includes a crank arm (201). One end of the crank arm (201) is fixedly connected to the rotating shaft (001) that controls the opening and closing of the valve. The other end of the crank arm (201) is provided with a slide groove (202). A pin (203) is slidably connected inside the slide groove (202). One end of the pin (203) is fixedly connected to a connecting shaft (204). One end of the connecting shaft (204) is fixedly connected to the piston (3). When the valve is closed, the force is transmitted to the pin (203) through the crank arm (201). The pin (203) converts the torque generated by the rotation of the valve into a force in the linear direction.

6. A multi-stage adjustable slow-closing silent hydraulic cylinder for valves according to claim 1, characterized in that, The B oil port (5) is a strip-shaped hole, the length of which is less than 2 / 3 of the length of the cylindrical section of the piston cylinder (2), and the distance between its right end and the inner wall of the left end of the cylinder body (1) is less than the length of the cylindrical section of the piston cylinder (2).

7. A multi-stage adjustable slow-closing silent hydraulic cylinder for valves according to claim 1, characterized in that, The flow rate of the second throttle valve (9) is greater than the flow rate of the first throttle valve (8).

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