High-frequency pilot proportional valve

Abstract

The high-frequency pilot proportional valve comprises a controller, a proportional electromagnet and a valve assembly, the valve assembly comprises a valve body, a main valve element arranged in an inner cavity of the valve body and sealing covers used for sealing the two ends of the inner cavity, a pilot valve element is arranged in an inner hole of the main valve element in a sliding mode, and the two ends of the pilot valve element are connected with the sealing covers in a sliding and sealing mode. Control oil cavities located at the two ends of the main valve element are formed between the main valve element and the sealing covers. The pilot valve element is driven by the proportional electromagnet to axially move along an inner hole of the main valve element, a throttling opening of the main valve element is opened to adjust the pressure difference of the control oil cavities at the two ends, the pilot valve element is driven by the pressure difference to reciprocate along an inner cavity of the valve body, and the oil way communication state of the proportional valve is switched. The driving force of the proportional electromagnet and the displacement of the pilot valve element are not interfered by oil pressure, the movement of the main valve element of the proportional valve is driven by the pressure difference of the control oil cavities at the two ends, and the dynamic response speed, the working pressure and the control precision of the proportional valve are effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic control valve technology, and in particular to a high-frequency pilot proportional valve. Background Technology

[0002] The working principle of an electro-hydraulic proportional valve is as follows: the command signal is amplified by a proportional amplifier, and a proportional current is output to the proportional electromagnet of the valve. The proportional electromagnet outputs force and moves the valve core proportionally, thereby controlling the flow rate and changing the direction of the fluid flow proportionally, thus achieving position or speed control of the actuator. In some applications requiring high position or speed accuracy, a closed-loop control system can be formed by detecting the displacement or speed of the actuator. According to the Bernoulli effect, the flow rate through the throttling orifice is related not only to the flow cross-sectional area of ​​the orifice but also to the pressure difference across the orifice. Proportional valves directly driven by proportional electromagnets will have deteriorated proportional characteristics when the load pressure difference changes due to the Bernoulli force on the valve core. They are generally suitable for low-flow operating conditions where response speed and control accuracy are not high. For some high-precision hydraulic control systems, such as thickness control during strip rolling in the metallurgical industry, precise data acquisition in the material testing machine industry, and hydraulic servo control systems in the aerospace industry, electro-hydraulic servo valves are generally used. Servo valves typically use zero-grind (critical) center valve cores, with almost no overlap between the valve port and the platform. This allows the valve to respond immediately and linearly to changes in the input signal. These require very precise manufacturing, resulting in a complex valve structure, high production and manufacturing costs, and high subsequent use and maintenance costs.

[0003] In the existing technology, electro-hydraulic proportional valves and electro-hydraulic servo valves cannot meet the control accuracy and cost requirements of control systems in terms of control accuracy and manufacturing cost. It is necessary to further optimize the valve body structure on the basis of the low manufacturing cost of proportional valves to improve their control accuracy. Utility Model Content

[0004] The purpose of this invention is to provide a high-frequency pilot-operated proportional valve, which improves the dynamic response speed, working pressure and control accuracy of the proportional valve by structural improvements based on the conventional proportional valve.

[0005] To solve the above-mentioned technical problems, the present invention provides a technical solution as follows: A high-frequency pilot-operated proportional valve includes: a valve assembly including a valve body, a main valve core disposed in the inner cavity of the valve body, and a cover sealing both ends of the inner cavity; a pilot valve core slidably disposed in the inner hole of the main valve core; the two ends of the pilot valve core are slidably and sealingly connected to the cover; an oil supply chamber P, an oil return chamber T, and working chambers A / B are formed between the main valve core and the valve body; control oil chambers located at both ends of the main valve core are formed between the pilot valve core, the main valve core, and the cover; and a proportional electromagnet, provided with power transmission... The push rod has a pilot valve core connected to one end and a return spring at the other end. The controller receives external command signals and converts the output drive current to the proportional electromagnet to drive the push rod to move. Under the action of the driving force of the proportional electromagnet and the return force of the spring, the pilot valve core moves axially along the inner hole of the main valve core, opening the throttle port of the main valve core to adjust the pressure difference between the two control oil chambers. Driven by the pressure difference of the control oil chamber, the main valve core reciprocates along the inner cavity of the valve body and switches the oil circuit connection state through its working step and the inner cavity of the valve body.

[0006] Furthermore, the push rod is rigidly connected to a displacement sensor, and the controller can receive feedback signals from the displacement sensor and external command signals to dynamically adjust the drive current output to the proportional electromagnet.

[0007] Furthermore, the output thrust of the proportional electromagnet is linearly related to the drive current, and the controller corrects the drive current in real time by comparing the deviation between the command signal and the feedback signal from the displacement sensor.

[0008] Furthermore, the pilot valve core's operating position within the main valve core's inner bore is determined by the combined force of the proportional electromagnet and the spring force; when the pilot valve core reaches the commanded position, the proportional electromagnet's thrust and the spring force are in equilibrium.

[0009] Furthermore, the pilot valve core moves relative to the main valve core, and the working step of the pilot valve core is misaligned with the throttle port of the main valve core, connecting the oil supply chamber and the control oil chamber. The control oil chambers at both ends of the main valve core form two sets of B-type hydraulic bridges. Driven by the pressure difference of the control oil chamber, the main valve core follows the pilot valve core until the pressure of the two control oil chambers is balanced. The working step of the pilot valve core corresponds to the throttle port of the main valve core, closing the throttle port.

[0010] Furthermore, when the main valve core is in the zero position, the oil supply chamber P, the oil return chamber T, and the working oil chambers A / B are mutually closed; when the controller receives a positive command signal, the main valve core follows the pilot valve core in a positive displacement, the oil supply chamber P is connected to the working chamber B, and the working chamber A is connected to the oil return chamber T; when the controller receives a reverse command signal, the main valve core follows the pilot valve core in a reverse displacement, the oil supply chamber P is connected to the working chamber A, and the working chamber B is connected to the oil return chamber T.

[0011] The high-frequency pilot-operated proportional valve provided by this invention, compared with the prior art, isolates the interference of oil pressure fluctuations on the proportional electromagnet thrust and the pilot valve core through the cooperative structure of the main valve core and the pilot valve core, and the sliding seal between the pilot valve core and the cover. The proportional electromagnet only drives the displacement of the pilot valve core, and the displacement of the pilot valve core depends on the balance between the force of the proportional electromagnet and the force of the spring. The movement of the main valve core of the proportional valve is driven by the pressure difference between the two control oil chambers, and the pressure difference of the control oil chamber depends on the displacement of the pilot valve core and is not affected by changes in system pressure and flow. This effectively improves the dynamic response speed, working pressure, and control accuracy of the proportional valve. In particular, by rigidly connecting the proportional electromagnet push rod to the displacement sensor, the controller and the proportional electromagnet form a closed-loop control system. The controller receives external command signals and feedback signals from the displacement sensor, calculates and compares the deviation between the command signal and the feedback signal from the displacement sensor, and corrects the positive drive current in real time according to the deviation until the feedback signal from the displacement sensor matches the command signal. This achieves dynamic adjustment of the drive current output of the proportional electromagnet, effectively increasing the response speed and control accuracy of the pilot valve core. Attached Figure Description

[0012] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the figures in the drawings do not constitute a limitation on scale.

[0013] Figure 1 This is a schematic diagram of the overall structure of the high-frequency pilot proportional valve in an embodiment of this utility model;

[0014] Figure 2 This is a schematic diagram of the valve body and valve core positions in the initial working state of the proportional valve in this embodiment of the present invention.

[0015] Figure 3 This is a schematic diagram showing the displacement of the pilot valve core of the proportional valve under a positive command signal in an embodiment of this utility model.

[0016] Figure 4 This is a schematic diagram showing the displacement of the pilot valve core of the proportional valve under a negative command signal in an embodiment of this utility model.

[0017] Explanation of reference numerals in the attached drawings: 1. Valve body; 11. First control chamber; 12. Second control chamber; 2. Main valve core; 21. Throttling port; 3. Pilot valve core; 4. Cover; 5. Fixing seat; 6. Spring; 7. End cover; 8. Proportional electromagnet; 81. Push rod; 9. Controller. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the various embodiments of this utility model will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this utility model to facilitate a better understanding of this application. However, the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0019] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0020] like Figure 1As shown, one embodiment of this utility model relates to a high-frequency pilot-operated proportional valve, including a controller 9, a proportional electromagnet 8 connected to the controller 9, and a valve assembly connected to the proportional electromagnet 8. The valve assembly includes a valve body 1 with an inner cavity. A main valve core 2 is provided in the inner cavity. The main valve core 2 and the inner cavity of the valve body 1 form an oil supply chamber P, an oil return chamber T, and working chambers A / B. The main valve core 2 has working steps corresponding to the oil supply chamber P, the oil return chamber T, and the working chambers A and B, respectively. By axially displacing the main valve core 2 relative to the valve body 1, its working steps close or open each cavity, controlling the change in the flow rate and direction of the liquid in the valve body 1. The two ends of the main valve core 2 in the axial direction are provided with caps 4 for sealing both sides of the inner cavity of the valve body 1. The main valve core 2 has an axially penetrating inner hole, and a pilot valve core 3 is coaxially mounted on the inner hole. The pilot valve core 3 is slidably connected to the inner hole, and its two axial ends are slidably and sealingly connected to the cover 4. The pilot valve core 3 has a working step corresponding to the throttle port 21 of the main valve core 2, which can seal the throttle port 21 and block the passage between the inner cavity of the main valve core 2 and the inner hole of the pilot valve core 3. The pilot valve core 3, the main valve core 2, and the cover 4 form control oil chambers located at both ends of the main valve core 2, namely a first control chamber 11 located near the proportional electromagnet 8 and a second control chamber 12 located opposite to it. The proportional electromagnet 8 provides linear output thrust, the magnitude of which is proportional to the driving current of the input coil. The proportional electromagnet 8 has a push rod 81 for power transmission. One end of the pilot valve core 3 is connected to the push rod 81, and the other end has a return spring 6. In one example, an end cap 7 is provided on the outer side of the cover 4 corresponding to the return spring 6. The end cap 7 has a groove facing the pilot valve core 3, and the spring 6 is housed in the groove. One end of the spring 6 abuts against the end cap 7, and the other end is connected to the pilot valve core 3 through a fixing seat 5. When the pilot valve core 3 moves axially, the spring 6 is compressed, causing elastic deformation. The controller 9 receives external command signals and converts them into output drive current signals to the coil, causing the proportional electromagnet 8 to generate a corresponding force, which acts on the pilot valve core 3 through the push rod 81, driving the pilot valve core 3 to move axially. The pilot valve core 3 is pushed by the proportional electromagnet 8 and reset by the spring 6, and moves axially along the inner hole of the main valve core 2. It adjusts the pressure difference between the two control oil chambers through the throttle port 21 of the main valve core 2. The pressure difference of the control oil chamber drives the main valve core 2 to reciprocate along the inner cavity of the valve body 1. The working step of the main valve core 2 and the inner cavity of the valve body 1 switch the oil circuit connection state, realize the change of liquid flow and direction in the proportional valve, and thus achieve the purpose of the proportional valve controlling the load according to the command signal.Through the cooperative structure of the main valve core 2 and the pilot valve core 3, and the sliding seal between the pilot valve core 3 and the cover 4, the interference of oil pressure fluctuations on the thrust of the proportional electromagnet 8 and the pilot valve core 3 is isolated. The proportional electromagnet 8 only drives the pilot valve core 3 to move, and the displacement of the pilot valve core 3 depends on the balance between the force of the proportional electromagnet 8 and the force of the spring 6. The movement of the main valve core 2 of the proportional valve is driven by the pressure difference between the two control oil chambers, and the pressure difference of the control oil chamber depends on the displacement of the pilot valve core 3. It is not affected by changes in system pressure and flow, which effectively improves the dynamic response speed, working pressure and control accuracy of the proportional valve.

[0021] One embodiment involves a high-frequency pilot-operated proportional valve. The proportional solenoid valve integrates a displacement sensor (not shown in the attached figure). The displacement sensor is rigidly connected to a push rod 81. When the push rod 81 drives the pilot valve core 3 to move, the displacement sensor can feed back the displacement signal to the controller 9. The proportional valve controller 9 calculates the command signal and the displacement sensor feedback signal, compares the actual displacement information of the push rod 81 and the pilot valve core 3 with the command signal, and corrects the drive current in real time according to the deviation value until the displacement sensor feedback signal is consistent with the command signal. This realizes the dynamic adjustment output of the drive current of the proportional electromagnet 8, effectively increasing the response speed and control accuracy of the pilot valve core 3.

[0022] like Figure 2-4 As shown, in one embodiment, a high-frequency pilot-operated proportional valve is involved. After the high-frequency pilot-operated proportional valve is powered on, it enters the initial working state. The working step of the pilot valve core 3 corresponds to the throttle port 21 of the main valve core 2, closing the throttle port 21 channel. The proportional valve controller 9 calculates the command signal and the displacement sensor feedback signal, and outputs a drive current to the coil of the proportional electromagnet 8 according to the result. The proportional electromagnet 8 pushes the pilot valve core 3 to run in the main valve core 2. The running position of the pilot valve core 3 in the inner hole of the main valve core 2 is determined by the thrust of the proportional electromagnet 8 and the force of the spring 6. When the pilot valve core 3 runs to the command position, the thrust of the proportional electromagnet 8 and the force of the spring 6 are in a balanced state. When the pilot valve core 3 moves relative to the main valve core 2 under the thrust of the proportional electromagnet 8 and the restoring force of the spring 6, the working step of the pilot valve core 3 is misaligned with the throttle port 21 of the main valve core 2. Pressurized fluid flows through the throttle port to one of the control oil chambers, forming two sets of B-type hydraulic bridges at both ends of the main valve core 2. Driven by the pressure difference in the control oil chambers, the main valve core 2 follows the pilot valve core 3 until the pressures of the two control oil chambers are balanced. The working step of the pilot valve core 3 then corresponds to the throttle port 21 of the main valve core 2, closing the throttle port 21. Through the linear movement of the main valve core 2 within the valve body 1, the on / off relationship between the supply chamber, working chamber, and return chamber within the valve body 1 is changed, realizing the change in the fluid flow rate and direction within the proportional valve, thereby achieving the purpose of the proportional valve controlling the load according to the command signal.

[0023] like Figure 2 As shown in one example, after the high-frequency pilot proportional valve is powered on, it enters the initial working state. In the absence of a command signal input, the working step of the main valve core 2 simultaneously closes the P, T, A, and B oil ports, that is, the oil supply chamber P, the oil return chamber T, and the working oil chambers A / B are mutually closed and not connected to each other; the working step of the pilot valve core 3 closes the throttle port 21 of the main valve core 2. At this time, the pressure of the control oil chambers at both ends of the main valve core 2 is the same, and there is no pressure difference. Therefore, the main valve core 2 is in a dynamic zero position in the valve body 1, and there is no flow output at the working oil port of the proportional valve at this time.

[0024] like Figure 3 As shown, when a positive command signal is input to the controller 9, the controller 9 receives the positive command signal and outputs a drive current to the coil. Under the action of the push rod 81 and the spring 6, the pilot valve core 3 moves to the right by a certain displacement. At this time, the working step of the pilot valve core 3 is misaligned with the throttle port 21, creating a fluid channel on the left side of the throttle port 21 of the main valve core 2. The pressurized oil enters the first control chamber 11 at the left end of the main valve core 2 through the throttle port 21. Since the pressure in the first control chamber 11 at the left end of the main valve core 2 is higher than the pressure in the second control chamber 12 at the right end, the main valve core 2 quickly follows the pilot valve core 3 to the right under the pressure, until the working step of the pilot valve core 3 re-closes the throttle port 21 of the main valve core 2. When the pressure in the control oil chambers at both ends is balanced, the main valve core 2 stops at a new position. Due to the rightward movement of the main valve core 2 in the inner cavity of the valve body 1, the oil supply chamber P of the proportional valve is connected to the working chamber B, and the working chamber A is connected to the return oil chamber T, completing the flow output of the corresponding command signal and driving the load to work.

[0025] like Figure 4 As shown, when a negative command signal is input to the controller 9, the pilot valve core 3 moves a certain displacement to the left under the action of the spring 6 and the push rod 81. At this time, the working step of the pilot valve core 3 is misaligned with the throttle port 21, creating a fluid channel on the right side of the throttle port 21 of the main valve core 2. The pressurized oil enters the second control chamber 12 at the right end of the main valve core 2 through the throttle port 21. Since the pressure in the second control chamber 12 at the right end of the main valve core 2 is higher than the pressure in the first control chamber 11 at the left end, the main valve core 2 quickly follows the pilot valve core 3 to move to the left under the pressure until the working step of the pilot valve core 3 re-closes the throttle port 21 of the main valve core 2. When the pressure in the control oil chambers at both ends is balanced, the main valve core 2 stops at a new position. Due to the leftward movement of the main valve core 2 in the inner cavity of the valve body 1, the oil supply chamber P of the proportional valve is connected to the working chamber A, and the working chamber B is connected to the return oil chamber T, completing the flow output of the corresponding command signal and driving the load to work. The pressure of the control oil chambers at both ends of the main valve core 2 is changed by the movement of the pilot valve core 3. Driven by the pressure, the main valve core 2 runs in the inner cavity of the valve body 1, realizing the high-frequency operation of the proportional valve.

[0026] The high-frequency pilot-operated solenoid valve provided by this invention, through the cooperative structure of the main valve core and the pilot valve core, and the sliding seal between the pilot valve core and the cover, isolates the interference of oil pressure fluctuations on the proportional electromagnet thrust and the pilot valve core. The proportional electromagnet only drives the displacement of the pilot valve core, and the displacement of the pilot valve core depends on the balance between the force of the proportional electromagnet and the force of the spring. The movement of the main valve core of the proportional valve is driven by the pressure difference between the two control oil chambers, and the pressure difference of the control oil chamber depends on the displacement of the pilot valve core, and is not affected by changes in system pressure and flow, effectively improving the dynamic response speed, working pressure, and control accuracy of the proportional valve. In particular, through the rigid connection of the proportional electromagnet push rod to the displacement sensor, the controller and the proportional electromagnet form a closed-loop control system. The controller receives external command signals and feedback signals from the displacement sensor, calculates and compares the deviation value between the command signal and the feedback signal of the displacement sensor, and corrects the positive drive current in real time according to the deviation value until the feedback signal of the displacement sensor is consistent with the command signal, realizing the dynamic adjustment output of the drive current of the proportional electromagnet, effectively increasing the response speed and control accuracy of the pilot valve core.

[0027] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A high-frequency pilot-operated proportional valve, characterized in that, include: The valve assembly includes a valve body (1), a main valve core (2) is provided in the inner cavity of the valve body (1), and a cover (4) that seals both ends of the inner cavity. A pilot valve core (3) is slidably provided in the inner hole of the main valve core (2). The two ends of the pilot valve core (3) are slidably sealed to the cover (4). An oil supply chamber P, an oil return chamber T and a working chamber A / B are formed between the main valve core (2) and the valve body (1). A control oil chamber located at both ends of the main valve core (2) is formed between the pilot valve core (3), the main valve core (2) and the cover (4). The proportional electromagnet (8) is provided with a push rod (81) for power transmission. One end of the pilot valve core (3) is connected to the push rod (81), and the other end is provided with a return spring (6). The controller (9) receives external command signals, converts the output drive current to the proportional electromagnet (8), and drives the push rod (81) to move. Under the driving force of the proportional electromagnet (8) and the restoring force of the spring (6), the pilot valve core (3) moves axially along the inner hole of the main valve core (2) to open the throttle port (21) of the main valve core (2) to adjust the pressure difference between the two ends of the control oil chamber. The main valve core (2) moves back and forth along the inner cavity of the valve body (1) under the pressure difference of the control oil chamber, and switches the oil circuit connection state through its working step and the cooperation with the inner cavity of the valve body (1).

2. The high-frequency pilot-operated proportional valve according to claim 1, characterized in that, The push rod (81) is rigidly connected to a displacement sensor. The controller (9) can receive feedback signals from the displacement sensor and external command signals, and dynamically adjust the driving current output to the proportional electromagnet (8).

3. The high-frequency pilot-operated proportional valve according to claim 2, characterized in that, The output thrust of the proportional electromagnet (8) is linearly related to the drive current. The controller (9) corrects the drive current in real time by comparing the deviation between the command signal and the feedback signal from the displacement sensor.

4. The high-frequency pilot-operated proportional valve according to claim 1, characterized in that, The operating position of the pilot valve core (3) in the inner hole of the main valve core (2) is determined by the thrust of the proportional electromagnet (8) and the force of the spring (6). When the pilot valve core (3) moves to the command position, the thrust of the proportional electromagnet (8) and the force of the spring (6) are in balance.

5. The high-frequency pilot-operated proportional valve according to claim 1, characterized in that, The pilot valve core (3) moves relative to the main valve core (2). The working step of the pilot valve core (3) is misaligned with the throttle port (21) of the main valve core (2), connecting the oil supply chamber and the control oil chamber. The control oil chambers at both ends of the main valve core (2) form two sets of B-type hydraulic bridges. The main valve core (2) moves with the pilot valve core (3) under the pressure difference of the control oil chamber until the pressure of the two control oil chambers is balanced. The working step of the pilot valve core (3) corresponds to the throttle port (21) of the main valve core (2), closing the throttle port (21).

6. The high-frequency pilot-operated proportional valve according to claim 5, characterized in that, When the main valve core (2) is in the zero position, the oil supply chamber P, the oil return chamber T, and the working oil chambers A / B are mutually closed, and the working step of the pilot valve core (3) closes the throttle port (21) of the main valve core (2); when the controller (9) receives a positive command signal, the main valve core (2) follows the pilot valve core (3) to move in the positive direction, the oil supply chamber P is connected to the working chamber B, and the working chamber A is connected to the oil return chamber T; when the controller (9) receives a reverse command signal, the main valve core (2) follows the pilot valve core (3) to move in the reverse direction, the oil supply chamber P is connected to the working chamber A, and the working chamber B is connected to the oil return chamber T.

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