Electro-hydraulic servo valve with slide valve clamping stagnation protection function

Abstract

The invention belongs to the technical field of mechanical engineering, and relates to an electro-hydraulic servo valve with a slide valve clamping stagnation protection function, the electro-hydraulic servo valve comprises a prestage, a power amplification stage and a slide valve stage, a slide valve clamping stagnation protection device is arranged in the slide valve stage, and the clamping stagnation protection device is divided into a left part and a right part which are in bilateral symmetry and consistent in principle; the clamping stagnation protection device is composed of a left pressure relief piston, a right pressure relief piston, a reset spring and a plug. Clamping stagnation protection device installation cavities are symmetrically formed in the sliding valve level shell along the two sides of the center oil return way. The left pressure relief piston and the right pressure relief piston are arranged in the two installation cavities respectively, and the opposite ends of the pressure relief pistons are matched with the reset springs respectively. The valve shell is matched with the pressure relief piston, and a spring cavity, a rod cavity and a rodless cavity are sequentially formed from inside to outside. An internal flow channel is further machined in the servo valve shell, and a left side receiving cavity is communicated with a right side pressure relief piston rod cavity and a left side pressure relief piston rodless cavity. And meanwhile, the right receiving cavity is communicated with a rod cavity of the left pressure relief piston and a rodless cavity of the right pressure relief piston. According to the invention, when the valve core is blocked by pollutants, the low-pressure side control cavities at the two sides of the valve core are decompressed by utilizing the blocking protection device under the instruction signal of the blocking protection function triggering threshold current, so that the purposes of further improving the driving pressure difference of the valve core, increasing the driving force and overcoming the blocking of the pollutants are achieved. The current threshold triggered by the clamping stagnation protection function can be changed by adjusting the pre-tightening force of the reset spring, and normal work of the servo valve and the clamping stagnation protection function do not interfere with each other. Therefore, the anti-pollution capacity and reliability of the servo valve are remarkably improved, and the external field use and maintenance cost of the servo valve is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical engineering and relates to an electro-hydraulic servo valve with a slide valve sticking protection function. Background Art

[0002] At present, electro-hydraulic servo valves are widely used in aircraft, ships, aviation, aerospace, metallurgy and other fields, and are mostly equipped in key parts of control systems, so their stability and reliability are particularly important. Since the clearance of the servo valve slide valve is only (1-5) microns, it is particularly sensitive to excess matter. However, due to factors such as the difficulty in controlling the cleanliness of the servo valve working medium and the external use environment, excess matter contaminates the servo valve, causing the slide valve core to be stuck and causing the servo valve to be uncontrolled. Failures such as the driving force on the valve core are closely related to the anti-pollution ability of the slide valve. The driving force of the valve core can be increased by increasing the valve core diameter (i.e. increasing the end area of ​​the valve core), but it also causes the valve core mass to increase and the dynamic performance of the servo valve is greatly reduced. Therefore, without changing the valve core diameter, increasing the driving pressure difference on both sides of the valve core has become a breakthrough in increasing the valve core driving force and improving the anti-pollution ability of the slide valve.

[0003] Therefore, designing an electro-hydraulic servo valve with a slide valve sticking protection function can not only increase the valve core driving pressure difference, effectively avoid the influence of excess objects on the servo valve, and improve the reliability of the servo valve, but also take into account the overall performance of the servo valve. It has very important theoretical significance and engineering application value. Summary of the invention

[0004] The purpose of the present invention is as follows: In order to achieve the above-mentioned purpose of the invention, the present invention provides an electro-hydraulic servo valve with a slide valve jam protection function, which can ensure that when the valve core is jammed by contaminants, under the command signal of the jam protection function triggering the threshold current, the jam protection device is used to release the pressure in the low-pressure control chamber on both sides of the valve core, so as to further increase the valve core driving pressure difference, increase the driving force, and overcome the jamming of contaminants. And the current threshold triggered by the jam protection function can be changed by adjusting the preload of the reset spring, so as to achieve the non-interference between the normal operation of the servo valve and the jam protection function. Thereby significantly improving the anti-pollution ability and reliability of the servo valve, and effectively reducing the field use and maintenance costs of the servo valve.

[0005] The technical scheme of the present invention is as follows: the present invention designs an electro-hydraulic servo valve with a slide valve stuck protection function; it includes a pre-stage, a power amplifier stage, and a slide valve stage, and a slide valve stuck protection device is arranged in the slide valve stage, and the stuck protection device is divided into left and right parts, which are symmetrical and have the same principle; the stuck protection device is composed of left and right pressure relief pistons, a return spring, and a screw plug; the slide valve stage housing is symmetrically provided with a stuck protection device installation cavity on both sides of the central oil return oil circuit; the left and right pressure relief pistons are respectively placed in the two installation cavities, and the opposite ends of the pressure relief pistons are respectively matched with a return spring; the valve housing and the pressure relief piston are matched to form a spring cavity, a rod cavity, and a rodless cavity from the inside to the outside in sequence;

[0006] An internal flow channel is also processed on the servo valve housing to connect the left receiving chamber with the rod chamber of the right pressure relief piston and the rodless chamber of the left pressure relief piston; at the same time, the right receiving chamber is connected with the rod chamber of the left pressure relief piston and the rodless chamber of the right pressure relief piston.

[0007] Furthermore, the pressure relief piston includes two working shoulders and a spring supporting end.

[0008] Furthermore, the shell has an annular inner cavity which transitionally matches with the pressure relief piston to ensure that the pressure relief piston can move along the piston axis in the inner cavity of the shell.

[0009] Furthermore, the shell spring chamber also includes a spring support end for positioning the return spring; the return spring is fixed on both sides to the pressure relief piston support end and the shell support end to ensure that it is located at the axial position of the spring chamber; and the return spring is in a compressed state to ensure that a pre-tightening force is provided to the pressure relief piston toward the outside of the servo valve.

[0010] Furthermore, an oil return window is arranged between the spring chamber of the housing and the rod chamber, and is connected with the oil return circuit; when the pressure relief piston is located at the outermost side, the oil return window is closed; when the pressure relief piston is forced to move inwardly of the servo valve, the oil return window opens, and the rod chamber is connected with the oil return circuit, thereby achieving pressure relief in the rod chamber (i.e., the receiving chamber on the opposite side).

[0011] Furthermore, an oil return circuit is provided inside the spring support end of the housing, so that the spring chamber is connected to the oil return, thereby ensuring that the pressure inside the spring chamber is always zero during the movement of the pressure relief piston.

[0012] Furthermore, when the jam protection device is triggered in a critical state, the force on the end face of the rodless cavity of the pressure relief piston is balanced with the spring force of the spring cavity; the triggering current is guaranteed by the spring stiffness and compression amount.

[0013] Furthermore, the assembly and debugging process of the jam protection device includes: installing the left and right return springs in the spring cavity of the housing respectively, and then installing the pressure relief piston, and ensuring that both ends of the spring are fixed to the spring support end. Then the screw plug is screwed into the housing, and the thread seal prevents external leakage of oil. The left and right receiving cavities are connected with hydraulic oil, and the screw plug is rotated at the same time to push the pressure relief piston toward the inside of the housing; when the boss of the pressure relief piston overlaps the oil return window of the housing at zero (that is, the critical point of the oil return window opening), the installation and debugging of the jam protection device is completed.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0015] 1. The slide valve stuck protection device can ensure that when the slide valve is stuck, the pressure relief function is turned on by giving a trigger current, so that the pressure on one side of the valve core increases and the pressure on one side is completely relieved, which further increases the pressure difference on both sides of the valve core of the original servo valve, thereby achieving the function of improving the driving force of the valve core and overcoming the sticking of pollutants.

[0016] 2. The function of the slide valve sticking protection device is compatible with the normal working performance of the servo valve. When the sticking protection device is not triggered, it will not affect the normal working performance of the servo valve.

[0017] 3. The trigger current threshold of the slide valve jam protection device can be adjusted in time. The spring preload is adjusted by changing the spring stiffness and compression amount, thereby changing the control chamber pressure difference (i.e., the trigger current threshold value) when the pressure relief piston is balanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the pressure difference curve of the conventional servo valve drive;

[0019] Figure 2 This is a working principle diagram of the zero-position adjustable electro-hydraulic servo valve of the present invention;

[0020] Figure 3 This is a schematic diagram of the state of the jam protection device of the present invention when it is not working;

[0021] Figure 4 It is a schematic diagram of the working state of the left pressure relief piston of the jam protection device of the present invention;

[0022] Figure 5 is the pressure difference variation curve of the servo valve driving of the present invention;

[0023] Among them, 1 is the armature assembly, 2 is the power amplifier stage, 3 is the pressure relief piston, 4 is the spring support end, 5 is the return spring, 6 is the valve core, 7 is the oil return window, and 8 is the screw plug. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the present invention is described in detail below in conjunction with the drawings or specific implementation cases of the specification. It should be noted that some (but not all) of the disclosed examples are shown in the drawings. In fact, many different examples can be described and these examples should not be understood as being limited to the examples set forth herein. On the contrary, these examples are described so that the positive effects of the present invention are more reflected, and any parts not detailed in the text are regarded as known techniques or conventional technical means in the art.

[0025] The traditional electro-hydraulic servo valve includes a pre-stage and a slide valve stage. The pre-stage drives the armature assembly to deflect under the control current signal, so that the left and right receiving chambers of the power amplifier stage generate a driving pressure difference proportional to the current signal, driving the valve core to move. The linear relationship of the conventional servo valve driving pressure difference is as follows: Figure 1 shown.

[0026] The traditional electro-hydraulic servo valve mainly includes a pre-stage, a power amplifier stage, and a slide valve stage. The pre-stage includes a torque motor composed of upper and lower magnetic conductors, and an armature assembly composed of a spring tube, a feedback rod, etc.; the power amplifier stage includes but is not limited to a jet deflection structure; the slide valve stage includes a valve core and a housing (or a valve sleeve). The innovation of the present invention is that it includes a set of slide valve jam protection devices, and its slide valve jam prevention function is mainly realized by left and right pressure relief pistons, a reset spring, a pressure relief piston rod chamber oil supply oil circuit, a pressure relief oil circuit, and a screw plug.

[0027] In the specific implementation process of the present invention, an electro-hydraulic servo valve with a slide valve jam protection function is designed, which can ensure that when the valve core is jammed by pollutants, under the command signal of the jam protection function triggering the threshold current, the jam protection device is used to release the pressure in the low-pressure control chambers on both sides of the valve core, so as to further increase the valve core driving pressure difference, increase the driving force, and overcome the jamming of pollutants. And the current threshold triggered by the jam protection function can be changed by adjusting the preload of the reset spring, so as to achieve the non-interference between the normal operation of the servo valve and the jam protection function.

[0028] See attached Figures 2 to 4 The jamming protection device A includes left and right pressure relief pistons 3, a return spring 5, a pressure relief piston rod chamber oil supply circuit and a pressure relief oil circuit. The jamming protection device A is divided into two parts, which are symmetrical and have the same principle. The left receiving chamber of the servo valve is connected to the right pressure relief piston rod chamber and the left pressure relief piston rodless chamber, and the corresponding right receiving chamber is connected to the left pressure relief piston rod chamber and the right pressure relief piston rodless chamber. The pressure relief piston includes two working shoulders and a spring support end. The shell spring chamber also includes a spring support end for positioning the reset spring. The two sides of the reset spring are fixed to the pressure relief piston support end and the shell support end to ensure that it is located at the axial position of the spring chamber; and the reset spring is in a compressed state to ensure that the pressure relief piston is provided with a preload force toward the outside of the servo valve. There is a return oil circuit inside the shell spring support end, which connects the spring chamber with the return oil to ensure that the inside of the spring chamber is always at zero pressure during the movement of the pressure relief piston. A throttling window is provided at a position corresponding to the boss of the middle part of the pressure relief piston of the shell body and is connected with the oil return path.

[0029] When assembling and debugging the jam protection device, install the left and right return springs in the spring chamber of the housing, and then install the pressure relief piston. Make sure that both ends of the spring are fixed to the spring support end. Then screw the plug into the housing, and seal the thread to prevent external leakage of oil. Pass hydraulic oil through the left and right receiving chambers, and rotate the plug at the same time to push the pressure relief piston toward the inside of the housing. When the pressure relief piston shoulder overlaps the oil return window of the housing (that is, the critical point of the oil return window opening), the installation and debugging of the jam protection device is completed.

[0030] When the pressure relief piston is located at the outermost side, the oil return window is closed. When the pressure relief piston is forced to move inwardly of the servo valve, the oil return window opens, and the rod chamber is connected to the oil return oil circuit to achieve pressure relief in the rod chamber (i.e. the corresponding receiving chamber).

[0031] The servo valve can ensure that when the valve core is stuck, under the trigger signal, the low-pressure side of the control chamber on both sides of the valve core is relieved by using the sticking protection device, so as to further improve the driving force of the valve core and overcome the sticking of pollutants. The current threshold triggered by the sticking protection function can be changed by adjusting the preload of the reset spring, so as to achieve the non-interference between the normal operation of the servo valve and the sticking protection function.

[0032] Example 1: Taking a certain type of electro-hydraulic servo valve with a slide valve jam protection function as an example, a jam protection device is designed in the slide valve structure, and the jam protection device is divided into two parts, which are symmetrical and have the same principle. The left receiving chamber of the servo valve is connected to the right pressure relief piston rod chamber and the left pressure relief piston rodless chamber, and the corresponding left receiving chamber is connected to the right pressure relief piston rod chamber and the left pressure relief piston rodless chamber. The pressure relief piston includes two working shoulders and a spring support end. The shell spring chamber also includes a spring support end for positioning the reset spring. The reset spring is fixed on both sides to the pressure relief piston support end and the shell support end to ensure that it is located at the axial position of the spring chamber; and the reset spring is in a compressed state to ensure that the pressure relief piston is provided with a preload force toward the outside of the servo valve. There is an oil return oil circuit inside the shell spring support end, so that the spring chamber is connected to the return oil, ensuring that the inside of the spring chamber is always zero pressure during the movement of the pressure relief piston. There is a throttling window in the shell at the corresponding position of the middle shoulder of the pressure relief piston, and it is connected to the oil return oil circuit. When the pressure relief piston is located at the outermost side, the oil return window is closed. When the pressure relief piston is forced to move inwardly of the servo valve, the oil return window opens, and the rod chamber is connected to the oil return oil circuit to achieve pressure relief in the rod chamber (i.e. the corresponding receiving chamber).

[0033] This servo valve can ensure that when the valve core is stuck, under the trigger current signal greater than the rated current, the low-pressure side of the control chamber on both sides of the valve core is relieved by the sticking protection device, so as to further improve the driving force of the valve core and overcome the sticking of pollutants. And the current threshold triggered by the sticking protection function can be changed by adjusting the preload of the reset spring, so as to achieve the non-interference between the normal operation of the servo valve and the sticking protection function. The screw plug design is added, because the pressure of the receiving chamber is linear and has good consistency during normal operation, and the balance between the rodless chamber liquid pressure and the spring force can be achieved by adjusting the spring stiffness.

[0034] Example 2

[0035] Since the structure and principle of the jam protection device are symmetrical, the positive current signal is used as an example for explanation. The driving pressure difference control curve is shown below. Figure 5 shown.

[0036] It is known that the pressure relief piston 3 is subjected to the rodless chamber fluid pressure F 无 and spring force F 弹 By selecting the spring stiffness and designing the spring compression, it is ensured that the hydraulic pressure in the rodless chamber of the pressure relief piston is balanced with the spring force in the triggered state.

[0037] When the servo valve is operating normally, a positive current less than the rated current is given, and the jam protection device does not work. Figure 1 As shown, at this time, the fluid force F generated by the pressure in the left receiving chamber (and the rodless chamber of the pressure relief piston) 无 Smaller than the spring force F 弹 , the pressure relief piston is under the spring force F 弹 Under the action, it is tightly attached to the outer screw plug, and the oil return window is closed by the working shoulder of the pressure relief piston. At this time, the pressure of the left and right receiving chambers can be established normally and linearly, and the valve core moves normally under the action of the driving pressure difference (which is less than the rated driving pressure difference at this time). At this time, the jamming protection device has no effect on the normal working performance of the servo valve.

[0038] When the servo valve core is stuck, a positive current signal is given to the rated current. Although the pressure in the left and right receiving chambers can be established normally, the normal movement of the valve core is blocked due to the increased friction of the valve core, and the performance of the servo valve is affected. Continue to increase the current signal until it exceeds the trigger current. At this time, the hydraulic force F generated by the pressure in the left receiving chamber (and the rodless chamber of the pressure relief piston) 无 Greater than the spring force F 弹 At this time, the left pressure relief piston moves inward, the oil return window is opened, and the rod chamber of the left pressure relief piston is connected to the oil return circuit, which causes the right receiving chamber to complete pressure relief through the internal flow channel, the left rod chamber, the left oil return window, and the oil return circuit. At this time, the valve core driving pressure difference becomes the difference between the left receiving chamber pressure and the oil return pressure. In this process, the driving pressure difference on both sides of the valve core is greatly increased, helping the valve core to overcome the stagnation. At this time, the oil in the spring chamber flows to the oil return circuit through the internal oil channel of the housing support end to avoid the pressure in the spring chamber hindering the movement of the piston.

[0039] When the left pressure relief piston is opened, since the pressure in the right receiving chamber is the low-pressure oil return pressure, the liquid pressure in the rodless chamber of the right pressure relief piston is still less than the spring force, and the right pressure relief piston boss still closes the oil return window.

[0040] When the increased driving pressure difference helps the valve core to overcome the friction of excess objects and the servo valve core moves normally, the current signal is reduced, the pressure in the left receiving chamber is reduced, the pressure relief piston is reset under the action of the spring force, the return oil window is closed again, and the working cycle of the jam protection device is completed.

[0041] Since the structure and principle of the servo valve are symmetrical on the left and right, when the given negative current reaches the trigger signal, the pressure relief piston on the right opens, the pressure relief in the left receiving chamber is released, and the valve core driving pressure difference also increases, and the principle is the same.

[0042] Due to the uniqueness of the current signal and the working principle, the left and right pressure relief pistons have no synchronous working conditions, and the jam protection function is a functional design, not a product performance requirement. Therefore, there is no matching requirement for the left and right pressure relief pistons, and the positive and negative trigger signals are guaranteed by the stiffness and compression of the left and right return springs respectively.

[0043] The anti-jamming device is bilaterally symmetrical and has the same principle, including a pressure relief piston 3 and a return spring 5 to ensure the bidirectional movement of the valve core 6.

[0044] When the servo valve is working normally, assuming that a positive current is input, the armature assembly 1 deflects clockwise, at which time the pressure in the left receiving chamber increases and the pressure in the right receiving chamber decreases, and the left pressure relief piston 3 is subjected to the rodless chamber liquid pressure F 无 and spring force F 弹 By adjusting the spring preload, when the jam protection function triggers the current, F 无 =F 弹 Then in the working range less than the trigger current, F 无 <F 弹 , the left oil return window 7 is always closed, and the right pressure relief piston 3 is also closed. At this time, the jamming protection device does not work. When the valve core 6 is stuck and the pressure difference between the left and right receiving chambers is less than the trigger current, the valve core 6 cannot be driven. At this time, the current continues to increase until it exceeds the trigger current. The pressure in the left control chamber continues to rise, F 无 >F 弹 , the left pressure relief piston 3 opens; at this time, the right receiving chamber releases pressure through the left oil return window 7, and the right pressure relief piston 3 is still closed. The pressure difference on both sides of the valve core 6 is further increased, and the driving pressure difference pushes the valve core 6 to overcome the contaminants to prevent the slide valve from getting stuck. When the movement of the valve core 6 returns to normal, the input current is reduced to below the trigger current, and the pressure relief piston 6 is closed under the action of the reset spring 5, and the servo valve returns to normal operation. During the movement of the pressure relief piston, the spring chamber is always connected to the oil return circuit to avoid negative pressure or high pressure in the spring chamber as the pressure relief piston 3 moves.

[0045] When a negative current is input, the pressure in the right receiving chamber increases, and the pressure in the left receiving chamber decreases. The anti-stuck principle of the right pressure relief piston 3 and the right return spring 5 is the same as that on the left side.

[0046] For traditional servo valves, the internal integrated oil filter can avoid contamination of the pre-stage. The out-of-control failure caused by external contamination of the servo valve often occurs at the slide valve stage, and is mostly caused by contaminants stuck in the slide valve pair. Compared with the traditional servo valve, the jamming protection function included in the present invention can ensure that when the valve core is stuck, under the command signal greater than the trigger current, the jamming protection device is used to release the pressure on the low-pressure side of the control chamber on both sides of the valve core, so as to achieve the purpose of increasing the driving force of the valve core and overcoming the jamming of contaminants. In addition, the current threshold triggered by the jamming protection function can be changed by adjusting the preload of the reset spring, so as to achieve the non-interference between the normal operation of the servo valve and the jamming protection function.

[0047] The above specific implementation methods or cases are only used to explain the technical solutions of the present invention, and are not intended to limit the present application. Any parts not described in detail are deemed to be conventional technical means or common knowledge in the field. It can be understood by those skilled in the art that: based on the design concept of the present application, the technical solutions recorded in the aforementioned implementation methods should be adaptively modified, or some or all of the technical features therein should be replaced by equivalents. These modified, equivalently replaced, and adaptively improved technical solutions do not depart from the technical essence of the present invention and should all be covered within the scope of protection of the present application.

Claims

1. An electro-hydraulic servo valve with a slide valve sticking protection function, characterized in that: It includes a pre-stage, a power amplifier stage, and a slide valve stage. A slide valve jamming protection device is arranged in the slide valve stage. The jamming protection device is divided into two parts, which are symmetrical and have the same principle. The jamming protection device is composed of left and right pressure relief pistons, a return spring, and a screw plug. The valve housing of the slide valve stage is symmetrically provided with installation cavities for the jamming protection device on both sides of the central oil return oil passage. The left and right pressure relief pistons are respectively placed in the two installation cavities, and the opposite ends of the pressure relief pistons are respectively matched with a return spring. The valve housing and the pressure relief piston are matched to form a spring cavity, a rod cavity, and a rodless cavity from the inside to the outside in sequence. An internal flow channel is also processed on the servo valve housing to connect the left receiving chamber with the rod chamber of the right pressure relief piston and the rodless chamber of the left pressure relief piston; at the same time, the right receiving chamber is connected with the rod chamber of the left pressure relief piston and the rodless chamber of the right pressure relief piston.

2. An electro-hydraulic servo valve with a slide valve sticking protection function as claimed in claim 1, characterized in that: The pressure relief piston includes two working shoulders and a spring-supported end.

3. The electro-hydraulic servo valve with slide valve sticking protection function as claimed in claim 1, characterized in that: The valve housing has an annular inner cavity which is transitionally matched with the pressure relief piston to ensure that the pressure relief piston can move along the piston axis in the inner cavity of the housing.

4. The electro-hydraulic servo valve with slide valve sticking protection function as claimed in claim 3, characterized in that: The spring chamber of the valve housing also includes a spring support end for positioning the return spring; the two sides of the return spring are fixed to the pressure relief piston support end and the housing support end to ensure that it is located at the axial position of the spring chamber; and the return spring is in a compressed state to ensure that a pre-tightening force is provided to the pressure relief piston toward the outside of the servo valve.

5. The electro-hydraulic servo valve with slide valve sticking protection function as claimed in claim 4, characterized in that: An oil return window is set between the shell spring chamber and the rod chamber, and is connected to the oil return oil circuit; when the pressure relief piston is located at the outermost side, the oil return window is closed, and when the pressure relief piston is forced to move toward the inside of the servo valve, the oil return window opens, the rod chamber is connected to the oil return oil circuit, and the rod chamber is depressurized.

6. The electro-hydraulic servo valve with slide valve sticking protection function as claimed in claim 1, characterized in that: An oil return circuit is arranged inside the spring support end of the housing, so that the spring chamber is connected with the oil return, ensuring that the pressure inside the spring chamber is always zero during the movement of the pressure relief piston.

7. The electro-hydraulic servo valve with slide valve sticking protection function as claimed in claim 1, characterized in that: When the jam protection device is in the critical state of triggering, the force on the end face of the rodless cavity of the pressure relief piston is balanced with the spring force of the spring cavity; the triggering current is guaranteed by the spring stiffness and compression amount.

8. An electro-hydraulic servo valve with a slide valve sticking protection function as claimed in claim 1 or 7, characterized in that: The assembly and debugging process of the jam protection device includes: respectively installing the left and right return springs in the spring cavity of the housing, and then installing the pressure relief piston, ensuring that both ends of the spring are fixed to the spring support ends; then screwing the screw plug into the housing, and sealing the thread to prevent external leakage of oil; letting the hydraulic oil pass through the left and right receiving cavities, and rotating the screw plug at the same time to push the pressure relief piston toward the inside of the housing; when the boss of the pressure relief piston and the oil return window of the housing have zero overlap, the installation and debugging of the jam protection device is completed.

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