Three-stage servo valve with emergency protection function and control method

Abstract

The application discloses a three-stage servo valve with an emergency protection function and a control method, and the three-stage servo valve comprises a main valve spool, a main valve sleeve, a sliding pin, a rear end cover assembly, a first high-speed switch valve, a second high-speed switch valve and a pilot valve; the main valve spool is slidably sleeved in the main valve sleeve; the rear end cover assembly is butted at the end of the main valve sleeve; the sliding pin is slidably arranged in the inner cavity of the rear end cover assembly along the axial direction of the main valve spool; the adjusting nut and the adjusting backup nut are sequentially screwed on the sliding pin in the direction away from the main valve spool; the spring is sleeved on the sliding pin and located between the inner cavity end of the rear end cover assembly and the adjusting backup nut; the first oil cavity is formed between the inner cavity of the rear end cover assembly and the side wall of the sliding pin; the first high-speed switch valve and the second high-speed switch valve are used for controlling the oil supply state of the pilot valve; the pilot valve is used for controlling the movement direction and position of the main valve spool; and the hydraulic cylinder can be retracted at a low speed in case of failure, damage of the equipment is avoided, and the safety is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic servo control, in particular to a three-stage servo valve with emergency protection function and a control method. BACKGROUND

[0002] Hydraulic servo actuators are widely used in industrial automation, aerospace, automotive engineering and other fields, for precise displacement, speed, acceleration and force control. The core component of the electro-hydraulic servo valve can convert electrical signals into hydraulic signals to control the movement of the hydraulic cylinder.

[0003] However, the existing ordinary hydraulic servo actuator has a major safety hazard when the control system fails. Once the control system fails, the hydraulic cylinder may lose control and fully retract or fully extend at maximum speed. This uncontrolled movement can cause the equipment connected to the hydraulic servo actuator to suffer serious damage, even trigger more widespread system failures, causing huge economic losses and safety hazards.

[0004] To solve this problem, there are proportional valves with emergency protection function on the market. Its working principle is to set a superimposed electromagnetic reversing valve between the pilot valve and the main valve. When the electromagnetic reversing valve is powered on, the electromagnetic reversing valve is powered off when emergency protection is needed, cutting off the oil path between the pilot valve and the main valve, and using the spring force at both ends of the main valve spool to move the main valve spool to the preset position, achieving low-speed retraction of the hydraulic cylinder. However, this type of proportional valve has obvious limitations, mainly in the following two aspects: first, the response speed of the electromagnetic reversing valve is slow, which is difficult to meet the requirements of some high-speed response applications; second, in the normal working state, the spring force is always acting on the main valve spool, which will adversely affect the control accuracy of the main valve spool, especially in the high frequency band, the control accuracy decreases more significantly. Therefore, the existing proportional valve with emergency protection function cannot be directly applied to the three-stage servo valve scene that requires high frequency width, and the three-stage servo valve plays an irreplaceable role in many high-precision and high-speed hydraulic control systems.

[0005] In summary, there is an urgent market demand for three-stage servo valves with emergency protection function. It needs to respond quickly when the control system fails, allowing the hydraulic cylinder to retract at low speed, avoiding equipment damage and accidents, while maintaining high control accuracy and fast response capability in normal operation. However, existing technologies have not fully met this demand, therefore, developing a three-stage servo valve with emergency protection function has important practical significance and broad application prospects. SUMMARY

[0006] The purpose of the present application is to provide a three-stage servo valve with emergency protection function and a control method to solve the problems raised in the background.

[0007] To achieve the above object, the application provides the following scheme.

[0008] A three-stage servo valve with emergency protection function comprises a main valve spool, a main valve sleeve, a sliding pin, a rear end cover assembly, a first high-speed switch valve, a second high-speed switch valve and a pilot valve.

[0009] The main valve spool is slidably sleeved in the main valve sleeve.

[0010] The rear end cover assembly is connected to the end of the main valve sleeve.

[0011] The sliding pin is slidably arranged in the inner cavity of the rear end cover assembly along the axial direction of the main valve spool.

[0012] The adjusting nut and the adjusting reserve nut are sequentially screwed on the sliding pin in the direction away from the main valve spool.

[0013] A spring is sleeved on the sliding pin and located between the inner cavity end of the rear end cover assembly and the adjusting reserve nut.

[0014] A first oil cavity is formed between the inner cavity of the rear end cover assembly and the side wall of the sliding pin.

[0015] The first high-speed switch valve and the second high-speed switch valve are respectively used for controlling the oil supply state of the pilot valve.

[0016] The pilot valve is used for controlling the movement direction and position of the main valve spool.

[0017] Further, a valve sleeve first return oil port, a valve sleeve second working oil port, a valve sleeve pressure oil port, a valve sleeve first working oil port and a valve sleeve second return oil port are sequentially arranged on the main valve sleeve along the axial direction thereof.

[0018] Further, oil port channels are sequentially arranged on the main valve spool along the axial direction thereof and can respectively communicate with the valve sleeve first return oil port, the valve sleeve second working oil port, the valve sleeve pressure oil port, the valve sleeve first working oil port and the valve sleeve second return oil port.

[0019] Further, a left side return oil valve port, a left side pressure valve port, a right side pressure valve port and a right side return oil valve port are sequentially arranged on the valve spool wall opposite to the oil port channels.

[0020] The application also provides a control method of the three-stage servo valve with emergency protection function.

[0021] When the control system is in normal operation:

[0022] The first high-speed switch valve and the second high-speed switch valve are powered on, the first control oil port of the first high-speed switch valve is not communicated with the first return oil port, the pilot first load oil port and the pilot second load oil port of the pilot valve are not communicated, and the pilot valve can normally control the main valve spool;

[0023] The second control oil port of the second high-speed switch valve is communicated with the second oil inlet port and not communicated with the second return oil port, high-pressure oil delivered by the hydraulic source enters the pilot supply oil port of the pilot valve, the pilot valve can normally work, and meanwhile, the high-pressure oil delivered by the hydraulic source also enters the first oil chamber, so that the sliding pin moves to the leftmost side, and the movement of the main valve spool in the main valve sleeve is not limited by the sliding pin under the control of the pilot valve;

[0024] The valve sleeve pressure oil port is connected with high-pressure oil, the valve sleeve first return oil port and the valve sleeve second return oil port are connected with return oil, the valve sleeve first working oil port is connected with the extending chamber of the oil cylinder, and the valve sleeve second working oil port is connected with the retracting chamber of the oil cylinder;

[0025] When the sliding pin is pressed by oil pressure to the leftmost end, the movement ranges of the left end and the right end of the main valve spool are equal, the left return valve port, the left pressure valve port, the right pressure valve port and the right return valve port are all in the opening and closing critical state;

[0026] The main valve spool moves under the control of the pilot valve;

[0027] When the main valve core moves to the direction close to the sliding pin, the left return valve port and the right pressure valve port are opened, the left pressure valve port and the right return valve port are closed, and the oil cylinder piston rod extends;

[0028] When the main valve core moves to the direction away from the sliding pin, the left pressure valve port and the right return valve port are opened, the left return valve port and the right pressure valve port are closed, and the oil cylinder piston rod retracts;

[0029] When the control system fails:

[0030] The first high-speed switch valve and the second high-speed switch valve are powered off, the first control oil port of the first high-speed switch valve is communicated with the first return oil port, the pilot first load oil port and the pilot second load oil port of the pilot valve are communicated, the pressures at the two ends of the main valve spool are equal, the driving force of the main valve spool is zero, and the pilot valve loses the control of the main valve spool;

[0031] The second control oil port of the second high-speed switch valve is communicated with the second return oil port and not communicated with the second oil inlet port, the pilot supply oil port of the pilot valve and the first oil chamber are communicated with the return oil pipeline, the pilot valve loses power, and the sliding pin is matched with the movement of the main valve spool to realize the position adjustment of the main valve spool under the action of the spring.

[0032] According to the technical scheme, compared with the prior art, the beneficial effects of the present application are as follows:

[0033] 1. Enhanced equipment safety: when the control system fails, the hydraulic cylinder of the ordinary hydraulic servo actuator may be fully retracted or extended at the maximum speed, which is easy to damage the equipment. The invention cooperates the high-speed on-off valve, sliding pin, spring and other components to make the hydraulic cylinder retract at low speed when the fault occurs, avoid equipment damage and improve safety.

[0034] 2. Improved system reliability: the existing proportional valve with emergency protection function has slow response and high spring force affecting high-frequency control accuracy. The invention uses a high-speed on-off valve with a closing time of 10 ms and no spring force effect, which is suitable for high-frequency wide three-stage servo valve scenes and ensures stable and reliable system in normal and emergency states. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor under the premise of the drawings.

[0036] Figure 1 The hydraulic principle diagram of the three-stage servo valve in the embodiment of the present application;

[0037] Figure 2 The simulation structure schematic diagram of the main valve spool in the zero position under normal working condition of the control system in the embodiment of the present application;

[0038] Figure 3 The simulation structure schematic diagram of the main valve spool in the zero position under fault condition of the control system in the embodiment of the present application;

[0039] Figure 4 The simulation structure schematic diagram of the main valve spool in the zero position on the right side under fault condition of the control system in the embodiment of the present application;

[0040] Figure 5 The simulation structure schematic diagram of the main valve spool in the bias position under emergency protection condition of the control system in the embodiment of the present application.

[0041] BRIEF DESCRIPTION OF DRAWINGS

[0042] 1. first high speed on-off valve; 1-1. first control oil port; 1-2. first return oil port; 1-3. first oil inlet; 2. pilot valve; 2-1. pilot return oil port; 2-2. pilot oil supply port; 2-3. pilot first load oil port; 2-4. pilot second load oil port; 3. second high speed on-off valve; 3-1. second return oil port; 3-2. second oil inlet; 3-3. second control oil port; 4. main valve spool; 5. main valve sleeve; 6. first oil cavity; 7. sliding pin; 8. adjusting nut; 9. adjusting nut; 10. spring; 11. rear end cover assembly; 12. left side return oil valve port; 13. left side pressure valve port; 14. right side pressure valve port; 15. right side return oil valve port; 16. sleeve first return oil port; 17. sleeve second working oil port; 18. sleeve pressure oil port; 19. sleeve first working oil port; 20. sleeve second return oil port. DETAILED DESCRIPTION

[0043] The specific embodiments of the present application will be further described in the following detailed description of the application, taken in conjunction with the accompanying drawings and examples. The following examples are intended to illustrate the present application and are not intended to limit the scope of the application.

[0044] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0045] The terms "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified and limited, the term "a plurality of" means two or more.

[0046] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0047] In order to better understand the purpose, structure and function of the present application, the present application will be further described in detail below in conjunction with the drawings.

[0048] Embodiment

[0049] Referring to Figures 1-5 As shown in the drawings, the embodiment provides a three-stage servo valve with emergency protection function, which comprises a main valve spool 4, a main valve sleeve 5, a sliding pin 7, a rear end cover assembly 11, a first high-speed switch valve 1, a second high-speed switch valve 3 and a pilot valve 2.

[0050] The main valve spool 4 is slidably sleeved in the main valve sleeve 5.

[0051] The rear end cover assembly 11 is connected to the end of the main valve sleeve 5.

[0052] The sliding pin 7 is slidably arranged in the inner cavity of the rear end cover assembly 11 along the axial direction of the main valve spool 4.

[0053] The adjusting nut 8 and the adjusting reserve nut 9 are sequentially screwed on the sliding pin 7 in the direction away from the main valve spool 4.

[0054] The spring 10 is sleeved on the sliding pin 7, and the spring 10 is located between the inner cavity end of the rear end cover assembly 11 and the adjusting reserve nut 9.

[0055] The first oil cavity 6 is formed between the inner cavity of the rear end cover assembly 11 and the side wall of the sliding pin 7.

[0056] The first high-speed switch valve 1 and the second high-speed switch valve 3 are respectively used for controlling the oil supply state of the pilot valve 2.

[0057] The pilot valve 2 is used for controlling the movement direction and position of the main valve spool 4.

[0058] Specifically, the function of the second high-speed switch valve 3 is to control the oil supply of the pilot valve 2 and the pressure of the sliding pin oil cavity. When the electromagnet is powered on, the oil supply port of the pilot valve 2 and the sliding pin oil cavity are connected to the high-pressure oil supply circuit of the oil source, the sliding pin moves to the leftmost end, and the pilot valve 2 can normally control the movement of the main valve spool 4. When the electromagnet is powered off, the oil supply port of the pilot valve 2 and the sliding pin oil cavity are connected to the oil return circuit of the oil source, the sliding pin moves to the right under the action of the spring, the left movement of the main valve spool 4 is limited, and the pilot valve 2 loses the oil supply pressure and cannot normally control the main valve spool.

[0059] It should be noted that, as Figure 2 As shown in the drawings, the main valve sleeve 5 is sequentially provided with a sleeve first oil return port 16, a sleeve second working oil port 17, a sleeve pressure oil port 18, a sleeve first working oil port 19 and a sleeve second oil return port 20 along the axial direction thereof; and the main valve spool 4 is sequentially provided with oil port channels which can be respectively communicated with the sleeve first oil return port 16, the sleeve second working oil port 17, the sleeve pressure oil port 18, the sleeve first working oil port 19 and the sleeve second oil return port 20 along the axial direction thereof.

[0060] The valve core wall of the main valve spool 4 opposite to the oil port channel is further sequentially provided with a left oil return valve port 12, a left pressure valve port 13, a right pressure valve port 14 and a right oil return valve port 15.

[0061] The working principle of the three-stage servo valve is as follows:

[0062] When the control system works normally, the first high-speed switch valve 1 and the second high-speed switch valve 3 are powered on, the second control oil port 3-3 of the second high-speed switch valve 3 is not communicated with the second oil return port 3-1, the pilot first load oil port 2-3 and the pilot second load oil port 2-4 of the pilot valve 2 are not communicated, and the pilot valve 2 can normally control the main valve spool 4; the first control oil port 1-1 of the first high-speed switch valve 1 is communicated with the first oil inlet port 1-3 and not communicated with the first oil return port 1-2, the high-pressure oil from the hydraulic source enters the pilot oil supply port 2-2 of the pilot valve 2, and the pilot valve 2 can work normally, and at the same time, the high-pressure oil from the hydraulic source also enters the first oil chamber 6 between the rear cover assembly 11 and the sliding pin 7, and pushes the sliding pin 7 to the leftmost side, and the movement of the main valve spool 4 in the valve sleeve controlled by the pilot valve 2 is not limited by the sliding pin 7, Figure 2 Fig. 3 is a schematic view of the main valve spool 4 in zero position under the normal working condition of the three-stage servo valve. Figure 3 The middle valve sleeve pressure oil port 18 is connected with high-pressure oil, the valve sleeve first oil return port 16 and the valve sleeve second oil return port 20 are connected with oil return, the valve sleeve first working oil port 19 is connected with the extension chamber of the oil cylinder, and the valve sleeve second working oil port 17 is connected with the retraction chamber of the oil cylinder.

[0063] When the sliding pin 7 is pressed by oil to the leftmost end, the movement ranges of the left and right ends of the main valve core are equal, the left oil return valve port 12, the left pressure valve port 13, the right pressure valve port 14 and the right oil return valve port 15 are all in the switching critical state (defined as the zero position of the servo valve). The main valve spool 4 moves left or right under the control of the pilot valve 2 according to the “positive” or “negative” of the control signal. When the main valve spool 4 moves left, the left oil return valve port 12 and the right pressure valve port 14 are opened, the left pressure valve port 13 and the right oil return valve port 15 are closed, and the oil cylinder piston rod is extended; when the main valve core moves right, the left pressure valve port 13 and the right oil return valve port 15 are opened, the left oil return valve port 12 and the right pressure valve port 14 are closed, and the oil cylinder piston rod is retracted.

[0064] When the control system fails, the first high-speed switch valve 1 and the second high-speed switch valve 3 are powered off, the control oil port and the return oil port of the first high-speed switch valve 1 are communicated, the pilot first load oil port 2-3 and the pilot second load oil port 2-4 of the pilot valve 2 are communicated, the pressure at both ends of the main valve spool 4 is equal, the driving force of the main valve spool 4 is zero, and the pilot valve 2 loses control of the main valve spool 4; the second control oil port 3-3 of the second high-speed switch valve 3 is communicated with the second return oil port 3-1 and is not communicated with the second oil inlet port 3-2, the pilot oil supply port 2-2 of the pilot valve 2 and the first oil cavity 6 between the rear cover assembly 11 and the sliding pin 7 are communicated with the return oil line, the pilot valve 2 loses power, and the sliding pin 7 moves to the right under the action of the spring 10 by a small distance exceeding the main valve zero position, and the specific position is adjusted by the adjusting nut 8 and locked by the adjusting backup nut 9.

[0065] Specifically, the sliding pin 7 moves to the right under the elastic force of the spring 10 and is positioned by the adjusting nut 8, and the adjusting backup nut 9 prevents loosening.

[0066] When the control system fails, the main valve spool 4 is in the zero position or to the left of the zero position, as shown in FIG. 6, the main valve core is pushed to the right of the zero position by the sliding pin 7, as shown in FIG. 7. Figure 3 Figure 5 When the control system fails, the main valve spool 4 is in the zero position or to the left of the zero position, as shown in FIG. 6, the main valve core is pushed to the right of the zero position by the sliding pin 7, as shown in FIG. 7.

[0067] When the control system fails, the main valve spool 4 is in the zero position or to the left of the zero position, as shown in FIG. 6, the main valve core is pushed to the right of the zero position by the sliding pin 7, as shown in FIG. 7. Figure 4 Figure 5 When the control system fails, the main valve spool 4 is in the zero position or to the left of the zero position, as shown in FIG. 6, the main valve core is pushed to the right of the zero position by the sliding pin 7, as shown in FIG. 7.

[0068] The design of the three-stage servo valve body ensures that the relationship between the four oil ports of the main valve in this state is valve sleeve pressure oil port 18-valve sleeve second working oil port 17, valve sleeve first working oil port 19-valve sleeve first return oil port 16, and valve sleeve second return oil port 20, and the design of the servo valve mounting block ensures that the valve sleeve first working oil port 19 is connected to the rear cavity of the hydraulic cylinder and the valve sleeve second working oil port 17 is connected to the front cavity of the hydraulic cylinder, thereby ensuring that the hydraulic cylinder is retracted at low speed.

[0069] The principles and implementation modes of the present application are described by using specific examples in the present application, and the above examples are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, the specific implementation modes and application ranges will be changed according to the idea of the present application. In summary, the content of the specification should not be understood as a limitation of the present application.​​

Claims

1. A three-stage servo valve with emergency protection, characterized in that The main valve spool, the main valve sleeve, the sliding pin, the rear end cover assembly, the first high-speed switch valve, the second high-speed switch valve and the pilot valve are included. The main valve spool is slidably sleeved in the main valve sleeve. The rear end cover assembly is butted at the end of the main valve sleeve. The sliding pin is slidably arranged in the inner cavity of the rear end cover assembly along the axial direction of the main valve spool. The adjusting nut and the adjusting reserve nut are sequentially screwed on the sliding pin in the direction away from the main valve spool. The spring is sleeved on the sliding pin and located between the inner cavity end of the rear end cover assembly and the adjusting reserve nut. The first oil cavity is formed between the inner cavity of the rear end cover assembly and the side wall of the sliding pin. The first high-speed switch valve and the second high-speed switch valve are respectively used for controlling the oil supply state of the pilot valve. The pilot valve is used for controlling the movement direction and position of the main valve spool.

2. A three-stage servo valve with emergency protection according to claim 1, characterized in that The main valve sleeve is sequentially provided with a sleeve first return oil port, a sleeve second working oil port, a sleeve pressure oil port, a sleeve first working oil port and a sleeve second return oil port along the axial direction thereof.

3. A three-stage servo valve with emergency protection according to claim 2, characterized in that The main valve spool is sequentially provided with oil port channels which can be respectively communicated with the sleeve first return oil port, the sleeve second working oil port, the sleeve pressure oil port, the sleeve first working oil port and the sleeve second return oil port along the axial direction thereof.

4. A three-stage servo valve with emergency protection according to claim 3, characterized in that The main valve spool is sequentially provided with a left side return oil valve port, a left side pressure valve port, a right side pressure valve port and a right side return oil valve port on the spool wall opposite to the oil port channels.

5. A control method of the three-stage servo valve with emergency protection function according to claim 4, characterized in that, when the control system is in normal operation: the first high-speed switch valve and the second high-speed switch valve are powered on, the first control oil port and the first return oil port of the first high-speed switch valve are not communicated, the pilot first load oil port and the pilot second load oil port of the pilot valve are not communicated, and the pilot valve can normally control the main valve spool; the second control oil port of the second high-speed switch valve is communicated with the second oil inlet port and not communicated with the second return oil port, the high-pressure oil delivered by the hydraulic source enters the pilot oil supply port of the pilot valve, the pilot valve can normally work, and meanwhile the high-pressure oil delivered by the hydraulic source also enters the first oil cavity, so that the sliding pin moves to the leftmost side, and the movement of the main valve spool in the main valve sleeve controlled by the pilot valve is not limited by the sliding pin; the sleeve pressure oil port is connected with high-pressure oil, the sleeve first return oil port and the sleeve second return oil port are connected with return oil, the sleeve first working oil port is connected with the extension cavity of the oil cylinder, and the sleeve second working oil port is connected with the retraction cavity of the oil cylinder; when the sliding pin is pressed to the leftmost end by oil pressure, the movement ranges of the left end and the right end of the main valve spool are equal, and the left side return oil valve port, the left side pressure valve port, the right side pressure valve port and the right side return oil valve port are all in the switching critical state; the main valve spool moves under the control of the pilot valve; when the main valve core moves towards the sliding pin, the left side return oil valve port and the right side pressure valve port are opened, and the left side pressure valve port and the right side return oil valve port are closed, so that the oil cylinder piston rod extends; when the main valve core moves away from the sliding pin, the left side pressure valve port and the right side return oil valve port are opened, and the left side return oil valve port and the right side pressure valve port are closed, so that the oil cylinder piston rod retracts; when the control system fails: The first high-speed switch valve and the second high-speed switch valve are powered off, the first control oil port and the first return oil port of the first high-speed switch valve are communicated, the pilot first load oil port and the pilot second load oil port of the pilot valve are communicated, the pressure at both ends of the main valve spool is equal, the driving force of the main valve spool is zero, and the pilot valve loses control over the main valve spool; The second control oil port of the second high-speed switch valve is communicated with the second return oil port and is not communicated with the second oil inlet port, the pilot oil supply port of the pilot valve and the first oil cavity are communicated with the return oil line, the pilot valve loses power, and the sliding pin is in motion cooperation with the main valve spool to realize position adjustment of the main valve spool under the action of the spring.

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