Servo valve, servo valve maintenance method and device

Abstract

The present invention discloses a servo valve, a maintenance method and device for a servo valve, which are applied to a servo valve provided with a pilot valve, and the method comprises: obtaining a test flow curve of the servo valve loaded with a preset pressure, wherein the test flow curve is a curve in which the target flow output by the servo valve follows the change of the control signal; judging whether the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than a deviation threshold, wherein the flow calibration curve is a curve in which the target flow output by the servo valve under rated pressure follows the change of the control signal; if so, replacing the pilot valve according to the model information of the servo valve, and adjusting the zero deviation of the servo valve to a preset range. The maintenance method reduces the maintenance difficulty and maintenance cost of the servo valve.

Description

Technical Field

[0001] The present application relates to the technical field of servo valve maintenance, and in particular to a servo valve, a servo valve maintenance method and a servo valve maintenance device. Background Art

[0002] Since servo valves (such as three-stage nozzle flapper servo valves) can accurately control the position, pressure, speed and other advantages of the actuator, servo valves are widely used in the metallurgical industry in the rolling thickness control, straightening control, coiling control and other links, and their performance directly affects the product quality. Due to the high processing precision, complex structure and poor anti-pollution ability of servo valves, the failure rate is relatively high in actual applications; at the same time, due to the iterative update of servo valve products, it will cause difficulties in purchasing accessories, which increases the difficulty and cost of servo valve maintenance. Summary of the invention

[0003] In view of the above technical problems, a servo valve, a maintenance method and a device for a servo valve of the present invention reduce the maintenance difficulty and maintenance cost of the servo valve.

[0004] The embodiment of the present invention provides the following solution:

[0005] In a first aspect, an embodiment of the present invention provides a servo valve maintenance method, which is applied to a servo valve provided with a pilot valve, and the method comprises:

[0006] Acquire a test flow curve of a servo valve loaded with a preset pressure, wherein the test flow curve is a curve in which a target flow output by the servo valve changes with a control signal;

[0007] Determine whether the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than a deviation threshold, wherein the flow calibration curve is a curve in which the target flow output by the servo valve under rated pressure changes with the control signal;

[0008] If yes, the pilot valve is replaced according to the model information of the servo valve, and the zero offset of the servo valve is adjusted to a preset range.

[0009] In an optional embodiment, the target flow is the output flow of the servo valve in a no-load state, and obtaining a test flow curve of the servo valve loaded with a preset pressure includes:

[0010] Acquiring an adjustment range of the control signal;

[0011] Loading the preset pressure to the servo valve, and controlling the control signal to change within the adjustment interval to obtain the output flow;

[0012] The test flow curve is obtained according to the corresponding change relationship between the output flow and the control signal.

[0013] In an optional embodiment, the target flow is the internal leakage flow of the servo valve, and obtaining the test flow curve of the servo valve loaded with a preset pressure includes:

[0014] Acquiring an adjustment range of the control signal;

[0015] Loading the preset pressure to the servo valve, and controlling the control signal to change within the adjustment interval to obtain the internal leakage flow;

[0016] The test flow curve is obtained according to the corresponding change relationship between the internal leakage flow and the control signal.

[0017] In an optional embodiment, before replacing the pilot valve according to the model information of the servo valve, the method further includes:

[0018] Determine the replacement pilot valve based on the rated working pressure and control signal of the model information;

[0019] Determine whether the replacement pilot valve can replace the faulty pilot valve of the servo valve according to the specification and size of the model information, wherein the specification and size at least include the oil circuit size and the installation hole size;

[0020] If not, an adapter plate is prepared according to the specification size, and the servo valve and the alternative pilot valve are connected through the adapter plate.

[0021] In an optional embodiment, determining the replacement pilot valve according to the rated working pressure and the control signal of the model information includes:

[0022] If the rated working pressure and the control signal of the pilot valve are both greater than the rated working pressure and the control signal of the faulty pilot valve, the pilot valve is determined to be the replacement pilot valve.

[0023] In an optional embodiment, before adjusting the zero bias of the servo valve to a preset range, the method further includes:

[0024] Obtaining a no-load flow curve and a valve core displacement curve of a maintenance servo valve, wherein the maintenance servo valve is the servo valve in which the pilot valve has been replaced;

[0025] Determining whether the zero offset of the maintenance servo valve is greater than the preset range according to the no-load flow curve and the valve core displacement curve;

[0026] If so, the zero offset of the servo valve is adjusted to a preset range.

[0027] In a second aspect, an embodiment of the present invention further provides a servo valve, which is obtained by repairing through any method described in the first aspect.

[0028] In a third aspect, an embodiment of the present invention further provides a servo valve maintenance device, which is applied to a servo valve provided with a pilot valve, and the device comprises:

[0029] An acquisition module, used for acquiring a test flow curve of a servo valve loaded with a preset pressure, wherein the test flow curve is a curve in which a target flow output by the servo valve changes with a control signal;

[0030] A judgment module, used for judging whether the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than a deviation threshold, wherein the flow calibration curve is a curve in which the target flow output by the servo valve under rated pressure changes with the control signal;

[0031] The adjustment module is used to replace the pilot valve according to the model information of the servo valve and adjust the zero deviation of the servo valve to a preset range when the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than the deviation threshold.

[0032] In a fourth aspect, an embodiment of the present invention further provides an electronic device, comprising a processor and a memory, wherein the memory is coupled to the processor, and the memory stores instructions, which, when executed by the processor, enable the electronic device to perform the steps of any one of the methods described in the first aspect.

[0033] In a fifth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods described in the first aspect.

[0034] Compared with the prior art, the servo valve, the servo valve maintenance method and the servo valve maintenance device provided by the present invention have the following advantages:

[0035] The present invention obtains a test flow curve when the servo valve is loaded with a preset pressure, so as to characterize how the output target flow follows the change of the control signal after the servo valve is loaded with the preset pressure. When it is judged that the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than the deviation threshold, it can be accurately judged that the pilot valve of the servo valve is faulty. The pilot valve can be replaced according to the model information of the servo valve, and the zero deviation of the servo valve can be adjusted to the preset range to complete the maintenance of the servo valve, thereby reducing the maintenance difficulty and maintenance cost of the servo valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A schematic diagram of the structure of a three-stage nozzle flapper servo valve provided in an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of signal control of a three-stage nozzle flapper servo valve provided in an embodiment of the present invention;

[0039] Figure 3 A flow chart of a maintenance method of a servo valve provided by an embodiment of the present invention;

[0040] Figure 4 A schematic diagram of a no-load flow characteristic curve provided by an embodiment of the present invention;

[0041] Figure 5 A schematic diagram of an internal leakage characteristic curve provided by an embodiment of the present invention;

[0042] Figure 6 A schematic structural diagram of a servo valve maintenance device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the embodiments of the present invention.

[0044] The control principle of the servo valve equipped with a pilot valve is to achieve large flow control of the servo valve through the small flow control of the pilot valve. For example, in a two-stage nozzle baffle servo valve, the permanent magnet torque motor and the nozzle baffle constitute the first-stage electro-hydraulic conversion and power amplification mechanism, and the second-stage slide valve constitutes the hydraulic power amplification mechanism. The torque motor is composed of an armature assembly composed of a permanent magnet, upper and lower magnetic conductors, a control coil and a spring tube, a feedback rod, a baffle, and an armature. The feedback rod ball is inserted into the groove in the middle of the valve core. When the load pressure is a fixed value, the output flow of the valve is proportional to the input current signal, forming a force feedback closed loop.

[0045] The present invention will take a three-stage nozzle flapper servo valve as an example to specifically explain how to implement the maintenance method of the servo valve. The structure of the three-stage nozzle flapper servo valve is as follows: Figure 1As shown, the three-stage nozzle flapper servo valve signal control diagram is as follows Figure 2 The three-stage nozzle flapper servo valve is composed of a dedicated electronic controller, a two-stage nozzle flapper servo valve (referred to as a pilot valve) as a pre-stage and a third-stage high-power slide valve control valve. A displacement sensor is installed at one end of the third-stage valve core, and the valve core displacement is fed back to the electronic controller input end in the form of electrical feedback, forming a position closed loop.

[0046] See also Figure 3 A maintenance method for a servo valve provided in an embodiment of the present invention is applied to a servo valve provided with a pilot valve, and the method comprises:

[0047] S11, obtaining a test flow curve of a servo valve loaded with a preset pressure, wherein the test flow curve is a curve in which a target flow output by the servo valve changes with a control signal.

[0048] Specifically, the test flow curve can be obtained through the servo valve test bench. The servo valve test bench is an instrument used to test the performance of the servo valve. The preset pressure can be selected and determined according to the model of the servo valve. For example, the preset pressure is set to 7MPa. During the loading process, the corresponding data of the target flow output by the servo valve following the change of the control signal is recorded, and the test flow curve can be generated by fitting the data.

[0049] In a specific embodiment, the target flow is the output flow of the servo valve in a no-load state, and a test flow curve of the servo valve loaded with a preset pressure is obtained, including: obtaining the adjustment range of the control signal; loading the preset pressure to the servo valve, and controlling the control signal to change within the adjustment range to obtain the output flow; and obtaining the test flow curve based on the corresponding change relationship between the output flow and the control signal.

[0050] Specifically, the no-load state of the servo valve means that there is no load to be pushed installed on its output port. A flow meter is directly installed on the oil outlet pipe of the output port, and the output flow of the servo valve is recorded by the flow meter. The adjustment range of the control signal can be a current range; it can also be a voltage range, for example, 0-10V. When the control signal is 0V, the opening of the servo valve is 0, and when the control signal is 10V, the opening of the servo valve is maximum. After loading the preset pressure to the servo valve, the control signal changes within the adjustment range, and the opening of the servo valve will change accordingly. The change in output flow is recorded, and a test flow curve is generated by fitting according to the corresponding change relationship between the output flow and the control signal. When the target flow is the output flow of the servo valve in the no-load state, the test flow curve represents the corresponding relationship between the output flow and the change of the control signal, that is, the no-load flow characteristic curve.

[0051] The no-load flow characteristic curve not only gives the polarity of the servo valve, but also obtains the gain, hysteresis, symmetry, linearity of the servo valve, and reveals the zero zone characteristics of the servo valve. The load test adjustment is shown in Table 1.

[0052] Table 1:

[0053]

[0054]

[0055] Depend on Figure 4 It can be concluded that its maximum hysteresis is 3.1%, the maximum positive flow rate is 11.4L / min, the maximum negative flow rate is 11.5L / min, the zero bias is 1%, and the dead zone is 2%.

[0056] In a specific embodiment, the target flow is the internal leakage flow of the servo valve, and a test flow curve of the servo valve loaded with a preset pressure is obtained, including: obtaining the adjustment range of the control signal; loading the preset pressure to the servo valve, and controlling the control signal to change within the adjustment range to obtain the internal leakage flow; and obtaining the test flow curve based on the corresponding change relationship between the internal leakage flow and the control signal.

[0057] Specifically, the interior of the servo valve is sealed by the joint surface of the valve stem and the valve core. The joint surface must ensure good finish. Internal leakage may be caused by damage to the joint surface or excessive joint clearance. The test bench can calculate the internal leakage flow rate through input flow, input pressure, output flow and output pressure. Similarly, a test flow curve can be obtained by loading the servo valve. When the target flow rate is the internal leakage flow rate, the test flow curve represents the corresponding relationship between the internal leakage flow rate and the change of the control signal, that is, the internal leakage characteristic curve.

[0058] The internal leakage of the double-nozzle two-stage electro-hydraulic servo valve is composed of the nozzle leakage of the first-stage electro-hydraulic conversion and power amplification and the zero-position leakage of the second-stage power slide valve. For new servo valves, the internal leakage characteristics can be used to evaluate the manufacturing quality of the valve, and for old servo valves, it can be used to determine the degree of wear of the valve. Test the internal leakage characteristic curve before putting it on the machine, and the test conditions are the same as Table 1. Figure 5 The maximum internal leakage of the servo valve is 1.28 L / min, the nozzle leakage of the first-stage electro-hydraulic conversion and power amplification is 0.45-0.5 L / min, and the zero-position leakage of the second-stage power slide valve is 0.78-0.83 L / min. After obtaining the test flow curve, proceed to step S12.

[0059] S12. Determine whether the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than a deviation threshold, wherein the flow calibration curve is a curve in which the target flow output by the servo valve under rated pressure changes with the control signal.

[0060] Specifically, the deviation threshold can be 5% of the flow value corresponding to the control information in the flow calibration curve, and of course, it can also be other set values. The flow calibration curve represents the change of the target flow output by the servo valve under rated pressure following the control signal. The target flow is the internal leakage flow or the output flow in the no-load state.

[0061] S13: If yes, replace the pilot valve according to the model information of the servo valve, and adjust the zero bias of the servo valve to a preset range.

[0062] Specifically, if the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than the deviation threshold, it means that the internal leakage of the pilot valve may exceed the standard or the feedback rod ball is worn. The pilot valve needs to be replaced according to the model information of the servo valve, and the zero deviation of the servo valve should be adjusted to the preset range.

[0063] In a specific embodiment, before replacing the pilot valve according to the model information of the servo valve, it also includes: determining a replacement pilot valve according to the rated working pressure and control signal of the model information; determining whether the replacement pilot valve can replace the faulty pilot valve of the servo valve according to the specification dimensions of the model information, wherein the specification dimensions at least include the oil circuit dimensions and the installation hole dimensions; if not, preparing an adapter plate according to the specification dimensions, and connecting the servo valve and the replacement pilot valve through the adapter plate.

[0064] Specifically, the model information of the servo valve can be obtained from the manual or nameplate. When the rated working pressure and control signal of the selected pilot valve are the same, the pilot valve is determined to be a replacement pilot valve. The specification size can be used to determine whether the replacement pilot valve can replace the faulty pilot valve of the servo valve. When the specification size is the same, it means that it can be installed correctly; on the contrary, when the specification size is different, it means that the installation may fail or hydraulic oil leakage may occur after installation. Prepare an adapter plate to transfer the servo valve and the replacement pilot valve to ensure that the pilot valve can be installed correctly.

[0065] In a specific implementation, determining a replacement pilot valve based on the rated working pressure and control signal of the model information includes: if the rated working pressure and control signal of the pilot valve are both greater than the rated working pressure and control signal of the faulty pilot valve, determining the pilot valve as a replacement pilot valve.

[0066] Specifically, taking the rolling thickness control in the metallurgical industry as an example, the roll gap value of the rolling mill is usually controlled by a servo valve, and the control signal of the servo valve is sent through the PLC controller on the production line. To ensure the stable production of the production line, the control signal cannot be modified at will. Therefore, it is necessary to ensure that the repaired servo valve can be directly controlled by the original control signal. If the rated working pressure and control signal of the pilot valve are greater than the rated working pressure and control signal of the faulty pilot valve, it can be determined that the pilot valve is a replacement pilot valve.

[0067] In a specific implementation, before adjusting the zero bias of the servo valve to a preset range, the method further includes:

[0068] Obtain a no-load flow curve and a valve core displacement curve of a maintenance servo valve, wherein the maintenance servo valve is a servo valve whose pilot valve has been replaced; determine whether the zero offset of the maintenance servo valve is greater than a preset range based on the no-load flow curve and the valve core displacement curve; if so, adjust the zero offset of the servo valve to the preset range.

[0069] Specifically, the valve core displacement curve represents the corresponding relationship between the output flow and the change of the valve core displacement, and the no-load flow curve represents the corresponding relationship between the output flow and the change of the control signal. The no-load flow curve and the valve core displacement curve can be obtained by performing a loading test on the test bench. If there is a zero deviation greater than the preset range, adjust the zero deviation knob of the servo valve to adjust the zero deviation of the servo valve to within the preset range.

[0070] Based on the same technical concept as the maintenance method, an embodiment of the present invention further provides a servo valve, which is obtained by maintenance by any of the methods described in the maintenance method.

[0071] Based on the same technical concept as the maintenance method, the embodiment of the present invention also provides a maintenance device for a servo valve, which is applied to a servo valve provided with a pilot valve, see Figure 6 , the device comprises:

[0072] An acquisition module 601 is used to acquire a test flow curve of a servo valve loaded with a preset pressure, wherein the test flow curve is a curve of a target flow output by the servo valve following a change in a control signal;

[0073] A judgment module 602 is used to judge whether the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than a deviation threshold, wherein the flow calibration curve is a curve in which the target flow output by the servo valve under rated pressure changes with the control signal;

[0074] The adjustment module 603 is used to replace the pilot valve according to the model information of the servo valve and adjust the zero deviation of the servo valve to a preset range when the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than the deviation threshold.

[0075] It can be understood that the test device and the test method provided in the embodiment of the present invention are in a one-to-one correspondence, and other modules included in the test device are not described in detail here.

[0076] Based on the same technical concept as the maintenance method, an embodiment of the present invention also provides an electronic device, including a processor and a memory, wherein the memory is coupled to the processor, and the memory stores instructions, which, when executed by the processor, enable the electronic device to perform the steps of any one of the methods described in the maintenance method.

[0077] Based on the same technical concept as the maintenance method, an embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of any one of the maintenance methods are implemented.

[0078] The technical solution provided in the embodiments of the present invention has at least the following technical effects or advantages:

[0079] 1. By obtaining the test flow curve of the servo valve loaded with a preset pressure, it can be characterized that after the servo valve is loaded with the preset pressure, the output target flow follows the change of the control signal. When it is judged that the flow deviation of the test flow curve and the flow calibration curve under the same control signal is greater than the deviation threshold, it can be accurately judged that the pilot valve of the servo valve is faulty. The pilot valve can be replaced according to the model information of the servo valve, and the zero deviation of the servo valve can be adjusted to the preset range to complete the maintenance of the servo valve, thereby reducing the maintenance difficulty and maintenance cost of the servo valve.

[0080] 2. The repairability and control accuracy of the servo valve are improved. If the original spare parts cannot be purchased due to product updates, an alternative pilot valve can be selected for replacement, which improves maintenance efficiency.

[0081] Finally, it should be noted that although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A maintenance method for a servo valve, characterized in that: Applied to a servo valve provided with a pilot valve, the method comprises: Acquire a test flow curve of a servo valve loaded with a preset pressure, wherein the test flow curve is a curve in which a target flow output by the servo valve changes with a control signal; Determine whether the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than a deviation threshold, wherein the flow calibration curve is a curve in which the target flow output by the servo valve under rated pressure changes with the control signal; If yes, replace the pilot valve according to the model information of the servo valve, and adjust the zero bias of the servo valve to a preset range; Before replacing the pilot valve according to the model information of the servo valve, the method further includes: Determine the replacement pilot valve based on the rated working pressure and control signal of the model information; Determine whether the replacement pilot valve can replace the faulty pilot valve of the servo valve according to the specification and size of the model information, wherein the specification and size at least include the oil circuit size and the installation hole size; If not, preparing an adapter plate according to the specification and size, and connecting the servo valve and the alternative pilot valve through the adapter plate; The step of determining a replacement pilot valve according to the rated working pressure and the control signal of the model information comprises: If the rated working pressure and the control signal of the pilot valve are both greater than the rated working pressure and the control signal of the faulty pilot valve, the pilot valve is determined to be the replacement pilot valve.

2. The maintenance method of the servo valve according to claim 1, characterized in that: The target flow is the output flow of the servo valve in a no-load state, and the step of obtaining a test flow curve of the servo valve loaded with a preset pressure includes: Obtaining an adjustment range of the control signal; Loading the preset pressure to the servo valve, and controlling the control signal to change within an adjustment interval to obtain the output flow; The test flow curve is obtained according to the corresponding change relationship between the output flow and the control signal.

3. The maintenance method of the servo valve according to claim 1, characterized in that: The target flow is the internal leakage flow of the servo valve, and the test flow curve of the servo valve loaded with a preset pressure is obtained, including Obtaining an adjustment range of the control signal; Loading the preset pressure to the servo valve, and controlling the control signal to change within an adjustment interval to obtain the internal leakage flow; The test flow curve is obtained according to the corresponding change relationship between the internal leakage flow and the control signal.

4. The maintenance method of the servo valve according to claim 1, characterized in that: Before adjusting the zero bias of the servo valve to a preset range, the method further includes: Obtaining a no-load flow curve and a valve core displacement curve of a maintenance servo valve, wherein the maintenance servo valve is the servo valve in which the pilot valve has been replaced; Determining whether the zero offset of the maintenance servo valve is greater than the preset range according to the no-load flow curve and the valve core displacement curve; If so, the zero offset of the servo valve is adjusted to a preset range.

5. A servo valve, characterized in that: The servo valve is repaired by the method described in any one of claims 1-4.

6. A maintenance device for a servo valve, characterized in that: The maintenance device is a device corresponding to any one of the methods described in claims 1-4; Applicable to a servo valve provided with a pilot valve, the device comprises: An acquisition module, used for acquiring a test flow curve of a servo valve loaded with a preset pressure, wherein the test flow curve is a curve in which a target flow output by the servo valve changes with a control signal; A judgment module, used for judging whether the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than a deviation threshold, wherein the flow calibration curve is a curve in which the target flow output by the servo valve under rated pressure changes with the control signal; The adjustment module is used to replace the pilot valve according to the model information of the servo valve and adjust the zero deviation of the servo valve to a preset range when the flow deviation between the test flow curve and the flow calibration curve under the same control signal is greater than the deviation threshold.

7. An electronic device, characterized in that: The electronic device comprises a processor and a memory, wherein the memory is coupled to the processor and stores instructions, and when the instructions are executed by the processor, the electronic device executes the steps of the method according to any one of claims 1 to 4.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method described in any one of claims 1 to 4 are implemented.

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