A new structure of digital servo valve with two degrees of freedom

Abstract

The application relates to a novel double-freedom digital servo valve with a structure comprising a valve body, a valve core, a centering spring, a stepping motor, an end cover, a bearing and a shaft coupling. The current commonly used electro-hydraulic servo valve can realize conversion of mechanical, electrical and hydraulic signals and can convert inputted small mechanical signals into high-power hydraulic signals. The servo valve is widely used due to the characteristics of fast dynamic response speed, high power weight, high precision, high load stiffness and the like. However, the servo valve is limited in application occasions due to the shortcomings of high machining precision requirement, high cost, poor anti-pollution capacity, high requirement for oil cleanliness and the like. The novel double-freedom digital servo valve designed in the application has the characteristics of simple structure, convenient machining, strong anti-pollution capacity, compact two-stage working structure, small volume, high inherent frequency, high control precision of the stepping motor of the pilot stage, easy realization of advanced control strategy, good overall dynamic and static performance of the valve and the like. The performance advantage is very outstanding.

Description

Technical Field

[0001] This invention relates to a novel dual-degree-of-freedom digital servo valve, belonging to the field of hydraulic technology. Background Technology

[0002] Currently, commonly used electro-hydraulic servo valves can convert electromechanical signals into hydraulic signals and transform small mechanical signals into high-power hydraulic signals. Therefore, they are both signal conversion elements and power amplification elements. Their characteristics such as fast dynamic response, large power and weight, high precision, and high load stiffness make them widely used. However, their disadvantages, such as high processing precision requirements, high cost, poor anti-contamination ability, and very high requirements for oil cleanliness, also limit their application. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a novel dual-degree-of-freedom digital servo valve, which features a simple structure, convenient processing, strong anti-pollution capability, compact two-stage working structure, small size, high natural frequency, high control precision of the pilot-stage stepper motor, easy implementation of advanced control strategies, and good overall dynamic and static performance of the valve, demonstrating outstanding performance advantages.

[0004] The technical solution of this invention is as follows: a novel dual-degree-of-freedom digital servo valve, comprising: a valve body, a valve core, an end cover, bearings, a coupling, a stepper motor, and a centering spring; characterized in that: the valve core and the valve body are clearance-fitted, allowing the valve core to rotate and move laterally within the valve body; the centering springs are located in the oil chambers at the left and right ends of the valve sleeve, respectively, and when the valve is in a non-working state, the elastic force of the centering springs maintains the valve core in a neutral position; one end of the coupling is fixedly connected to the stepper motor via a key, and the other end of the coupling is fixed to the right end of the valve core extending from the valve body via a key. The coupling has a keyway with an axial length greater than the valve core key length, allowing for axial horizontal movement of the valve core and radial rotation that is coaxial with the stepper motor. When the stepper motor rotates clockwise or counterclockwise, it drives the valve core to rotate clockwise or counterclockwise. The outer ring of the bearing remains fixed, while the inner ring of the bearing and the coupling are fixedly connected by a key. The outer ring of the bearing and the end cover are interference-fitted. The inner ring of the bearing can rotate with the coupling when the stepper motor is working. The end cover and the valve body are fixedly connected by bolts, and an O-ring seal is added between the end cover and the valve body to prevent oil leakage during valve core operation.

[0005] Preferably, the novel dual-degree-of-freedom digital servo valve has guide holes H, K, P, T, A, and B on the valve body, and guide holes M (pilot stage left centering port), N (pilot stage inlet), E, ​​F, G, and L (pilot stage return groove) distributed at different cross-sections of the valve core. Furthermore, guide holes M, N, and L are located at angles in both clockwise (forward) and counterclockwise (reverse) rotations of the valve core. By designing this angle appropriately, both the speed and reliability of oil inlet and outlet at this position can be guaranteed, and the control of oil inlet and outlet at ports A and B on the valve body can be effectively achieved by driving the power stage valve core. When the stepper motor is not in operation, the guide hole H and guide hole M are connected. At this time, the oil enters the oil chamber IV through the valve body inlet P, and then enters the oil chamber I and oil chamber VII through the guide hole E in the oil chamber IV. Since the areas of the left end face a and the right annular face b of the valve core are equal, the valve core still maintains the neutral position function and the valve core does not move laterally. Movement; When the stepper motor rotates clockwise by a certain angle, the valve core rotates in the same direction by the same angle, making the oil guide hole N and the oil guide hole K connected. At this time, some oil flows into the oil chamber II through the oil guide holes E and K. At this time, the left end annular surface c of the valve core is subjected to oil pressure. Since the area of ​​annular surface c is larger than that of annular surface b, the valve core will move to the right. At this time, the oil guide hole N and the oil guide hole K are misaligned and moved a certain distance, but they will still partially intersect. Thus, the oil in the valve body inlet P and the load port B are connected, and the oil in the valve body return port T and the load port A are connected. When the stepper motor rotates counterclockwise by a certain angle, the valve core rotates in the same direction by the same angle, causing the return oil groove L to connect with the guide oil holes H and K respectively. Oil in oil chambers I and II flows through the return oil groove L, through oil chamber III, and out through the valve body return oil port T. At this time, due to the continuous force on the right annular surface b of the valve core, the valve core will move to the left. Although the return oil groove L and the guide oil holes H and K will slide relative to each other, the oil will still remain connected. Therefore, the oil inlet P of the valve body connects with the oil inlet A, and the oil inlet T connects with the oil inlet B of the load. When the valve core rotates again until the guide oil hole M connects with the guide oil hole H of the valve body, the valve core returns to its neutral position.

[0006] As a preferred embodiment, the novel dual-degree-of-freedom digital servo valve integrates the pilot stage and power stage of the servo valve into the same valve core, located at the left and right ends of the same valve core, respectively. This results in a compact structure and high rigidity between the two stages. Such a structure reduces the processing difficulty of the valve core and valve body, significantly lowering processing costs. At the same time, the relatively large geometric dimensions of the pilot stage's oil supply and return ports make it less prone to clogging by extremely small particles mixed in the oil, providing excellent resistance to oil contamination and reducing the filtration requirements of the oil supply.

[0007] The beneficial effects of this invention are:

[0008] The present invention designs a novel dual-degree-of-freedom digital servo valve in which the pilot stage and power stage are integrated into the same valve core, located at the left and right ends of the same valve core, respectively. The structure is compact and the rigidity between the two stages is high. This structure reduces the difficulty of manufacturing the valve core and valve sleeve, and significantly reduces the manufacturing cost.

[0009] The pilot stage oil supply port and return port designed in this invention have relatively large geometric dimensions, making them less prone to clogging by extremely small particles mixed in the oil. They have excellent resistance to oil contamination and reduce the filtration level of the oil supply.

[0010] The pilot stage designed in this invention has M-hole (left centering oil port), N-hole (pilot stage oil inlet), and return groove L (pilot stage return groove) distributed on different cross sections of the valve core. Furthermore, the M-hole and N-hole are located at opposite angles when the valve core rotates clockwise (forward) and counterclockwise (backward). By rationally designing this angle, both the speed and reliability of oil inlet and return at this position can be guaranteed, and the control of oil inlet and return at the two load ports A and B can be effectively achieved by driving the power stage valve core, thus realizing the overall function of this valve.

[0011] The valve core designed in this invention is driven by a stepper motor and can rotate clockwise (forward) and counterclockwise (reverse) within the valve sleeve. This allows for rapid start-up, shutdown, and reversal of the valve core rotation, while maintaining high precision during this process. This results in good dynamic characteristics for controlling the oil circuit within the valve and high overall dynamic performance of the valve. Attached Figure Description

[0012] Appendix Figure 1 A schematic diagram of the overall assembly of the present invention;

[0013] Appendix Figure 2 A schematic diagram of the valve body structure of the present invention;

[0014] Appendix Figure 3 A schematic diagram of the valve core structure of the present invention;

[0015] Appendix Figure 4 A schematic diagram of the coupling connection structure of the present invention;

[0016] In the picture:

[0017] 1. Valve body, 2. Valve core, 3. End cover, 4. Bearing, 5. Coupling, 6. Stepper motor, 7. Centering spring. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to the specific structures shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0019] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the specific embodiment of the present invention adopts the following technical solution: It consists of 1. a valve body, 2. a valve core, 3. an end cover, 4. a bearing, 5. a coupling, 6. a stepper motor, and 7. a centering spring; characterized in that: the valve core 2 and the valve body 1 are in clearance fit, allowing the valve core 2 to rotate and move laterally within the valve body 1; the centering spring 7 is located in the oil chambers at the left and right ends of the valve sleeve, and when the valve is in a non-working state, the elastic force of the centering spring 7 maintains the valve core 2 in a neutral position; one end of the coupling 5 is fixedly connected to the stepper motor 6 via a key, and the other end of the coupling 5 is fixedly connected to the right end of the valve core 2 extending from the valve body via a key. The coupling 5 has a keyway, the axial length of which is greater than the key length of the valve core 2. This allows the valve core 2 to move horizontally in the axial direction and rotate radially with the stepper motor 6. When the stepper motor 6 rotates clockwise or counterclockwise, it drives the valve core 2 to rotate clockwise or counterclockwise. The outer ring of the bearing 4 remains fixed, while the inner ring of the bearing 4 and the coupling 5 are fixedly connected by a key. The outer ring of the bearing 4 and the end cover 3 are interference-fitted. The inner ring of the bearing 4 can rotate together with the coupling 5 when the stepper motor 6 is working. The end cover 3 and the valve body 1 are fixedly connected by bolts, and an O-ring seal is added between the end cover 3 and the valve body 1 to prevent oil leakage when the valve core 2 is working.

[0020] Furthermore, in the novel dual-degree-of-freedom digital servo valve, the valve body has guide holes H, K, P, T, A, and B. The valve core has guide holes M (pilot stage left centering port), N (pilot stage inlet), E, ​​F, G, and a return groove L (pilot stage return groove) distributed at different cross-sections of the valve core 2. The guide holes M, N, and L are positioned at angles in both clockwise (forward) and counterclockwise (reverse) directions when the valve core 2 rotates, through reasonable... From this design perspective, it ensures both the speed and reliability of oil inlet and outlet at this position, and also effectively controls the oil inlet and outlet of the two load ports A and B on the valve body 1 through the drive of the power stage valve core 2. When the stepper motor 6 is not in operation, the oil guide hole H and the oil guide hole M are connected. At this time, the oil enters the oil chamber IV through the oil inlet P of the valve body 1, and then enters the oil chamber I and oil chamber VII through the oil guide hole E in the oil chamber IV. Since the areas of the left end face a and the right annular face b of the valve core 2 are equal, the valve core 2 still maintains the neutral position function and does not move laterally. When the stepper motor 6 rotates clockwise by a certain angle, the valve core 2 rotates in the same direction by the same angle, making the oil guide hole N and the oil guide hole K connected. At this time, some oil flows into the oil chamber II through the oil guide hole E and the oil guide hole K. At this time, the left end ring surface c of the valve core 2 is subjected to oil pressure. Since the area of ​​the ring surface c is larger than that of the ring surface b, the valve core 2 will move to the right. At this time, the oil guide hole N and the oil guide hole K are misaligned and moved a certain distance, but they will still remain partially intersecting. Thus, the oil in the valve body 1 inlet P and the load oil port B are connected, and the oil in the valve body 1 return oil port T and the load oil port A are connected. When the stepper motor 6 rotates counterclockwise by a certain angle, the valve core 2 rotates in the same direction and by the same angle, so that the return oil groove L is connected to the guide oil hole H and the guide oil hole K respectively. The oil in oil chamber I and oil chamber II flows through the return oil groove L, through oil chamber III, and out through the return oil port T of valve body 1. At this time, because the right annular surface b of valve core 2 is continuously subjected to force, valve core 2 will move to the left. Although the return oil groove L and the guide oil hole H and the guide oil hole K will slide relative to each other, the oil will still be connected. Thus, the oil inlet P of valve body 1 is connected to the oil inlet A, and the oil inlet T is connected to the oil inlet B of the load. When valve core 2 rotates again until the guide oil hole M is connected to the guide oil hole H of valve body 1, valve core 2 returns to the neutral position function state.

[0021] Furthermore, in the novel dual-degree-of-freedom digital servo valve, the pilot stage and power stage of the servo valve are integrated into the same valve core 2, located at the left and right ends of the same valve core 2, respectively. This structure is compact and has high rigidity between the two stages. This reduces the machining difficulty of the valve core 2 and valve body 1, significantly lowering machining costs. At the same time, the relatively large geometric dimensions of the pilot stage oil supply port and oil return port make them less prone to clogging by extremely small particles mixed in the oil, providing excellent resistance to oil contamination and reducing the filtration level of the oil supply.

[0022] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

[0023] The working process of this invention is as follows:

[0024] First, technicians connect the servo valve of this invention, with the inlet P, return T, and load ports A and B respectively, to the inlet and outlet ports of the corresponding hydraulic cylinders or other applied working components. According to the requirements of the hydraulic cylinders or other applied working components, after energizing the stepper motor 6, its rotation angle and direction are controlled. When the stepper motor 6 rotates clockwise (positive direction) by a certain angle, the two guide holes N (pilot stage inlet) on the valve core connect with the guide hole K of the valve body 1, thereby causing the valve core 2 to move to the right. At this time, the inlet P and load ports... Oil is connected in port B, and oil is connected in port A and port T. When the technician controls the stepper motor 6 to rotate counterclockwise (reverse) by a certain angle, the two return oil grooves L on the valve core are connected to the oil guide holes H and K on the valve body 1, respectively. As a result, the valve core 2 moves to the left. At this time, oil is connected in port P and port A, and oil is connected in port B and port T. When the valve core 2 rotates back to the initial position and the oil guide hole M is connected to the oil guide hole H on the valve body 1, the valve core 2 returns to the neutral position.

[0025] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A two-degree-of-freedom digital servo valve, comprising: Valve body (1), valve core (2), end cap (3), bearing (4), coupling (5), stepper motor (6), centering spring (7); characterized in that: the valve core and valve body are clearance fit, the valve core (2) can rotate and move laterally within the valve body (1), the centering spring (7) is located in the oil chambers at the left and right ends of the valve sleeve respectively, and when the valve is in a non-working state, the elastic force of the centering spring (7) is used to keep the valve core (2) in the neutral position, one end of the coupling (5) is fixedly connected to the stepper motor (6) by a key, and the other end of the coupling (5) is fixedly connected to the right end of the valve core (2) extending out of the valve body by a key, the coupling (5) has a keyway, the axial length of the keyway is greater than the key length of the valve core (2), and the valve core (2) can move axially and laterally. The radial rotation is coaxial with the stepper motor (6). When the stepper motor (6) rotates clockwise and counterclockwise, it drives the valve core (2) to rotate clockwise and counterclockwise. The outer ring of the bearing (4) remains fixed. The inner ring of the bearing (4) and the coupling (5) are fixedly connected by a key. The outer ring of the bearing (4) and the end cover (3) are interference fit. The inner ring of the bearing (4) can rotate with the coupling (5) when the stepper motor (6) is working. The end cover (3) and the valve body (1) are fixedly connected by bolts. An O-ring is added between the end cover (3) and the valve body (1) to prevent oil leakage when the valve core (2) is working. The valve body (1) has an oil guide hole H, an oil guide hole K, an oil inlet P, an oil return port T, a load oil port A, and a load oil port B. The valve core (2) has an oil guide hole M, Oil guide holes N, E, F, G and L are distributed at different sections of the valve core (2), and oil guide holes M, N and L are at angles in both directions when the valve core (2) rotates clockwise and counterclockwise. By reasonably designing this angle, the speed and reliability of oil inlet and outlet can be guaranteed, and the control of oil inlet and outlet at the two load ports A and B on the valve body (1) can be well realized by driving the power stage valve core (2): When the stepper motor (6) is not working, oil guide holes H and M are connected. At this time, the oil enters the oil chamber IV through the oil inlet P of the valve body (1), and the oil enters the oil chamber I and oil chamber VII through the oil guide hole E in the oil chamber IV respectively. Since the left end face a of the valve core (2) The area of ​​the annular surface b on the right side of the valve core (2) is equal, so the valve core (2) still maintains the neutral position function at this time, and the valve core (2) does not move laterally: When the stepper motor (6) rotates clockwise by a certain angle, the valve core (2) rotates in the same direction by the same angle, so that the oil guide hole N and the oil guide hole K are connected. At this time, some oil flows into the oil chamber II through the oil guide hole E and the oil guide hole K. At this time, the annular surface c on the left end of the valve core (2) is subjected to oil pressure. Since the area of ​​the annular surface c is greater than that of the annular surface b, the valve core (2) will move to the right. At this time, the oil guide hole N and the oil guide hole K are misaligned and moved a certain distance, but they will still have some intersection. Then the oil inlet P of the valve body (1) and the oil inlet B of the load are connected, and the oil return port T of the valve body (1) and the oil inlet A of the load are connected.When the stepper motor (6) rotates counterclockwise by a certain angle, the valve core (2) rotates in the same direction by the same angle, so that the return oil groove L is connected to the guide oil hole H and the guide oil hole K respectively. The oil in oil chamber I and oil chamber II flows through the return oil groove L, through oil chamber III, and out through the return oil port T of the valve body. At this time, because the right annular surface b of the valve core (2) is continuously subjected to force, the valve core (2) will move to the left. Although the return oil groove L and the guide oil hole H and the guide oil hole K will slide relative to each other, the oil will still be connected. Thus, the oil inlet P of the valve body (1) is connected to the oil inlet A of the load, and the oil inlet T is connected to the oil inlet B of the load. When the valve core (2) rotates again to the point where the guide oil hole M is connected to the guide oil hole H of the valve body (1), the valve core (2) returns to the neutral position function state.

2. The dual-degree-of-freedom digital servo valve according to claim 1, characterized in that: The pilot stage and power stage of the servo valve are integrated into the same valve core (2), located at the left and right ends of the same valve core (2), respectively. The structure is compact and the rigidity between the two stages is large. This structure reduces the processing difficulty of the valve core (2) and valve body (1), which greatly reduces the processing cost. At the same time, the geometric dimensions of the pilot stage oil supply port and oil return port are relatively large, making them less likely to be blocked by extremely small particles mixed in the oil. This has a good ability to resist oil contamination and reduces the filtration level of the oil supply.

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