A piezoelectric proportional valve with direct valve core displacement measurement

Abstract

The present invention provides a piezoelectric proportional valve with direct valve core displacement measurement, comprising a valve body assembly, a piezoelectric driver, a valve core assembly, and a displacement measurement assembly; the valve body assembly forms a working medium flow channel and is equipped with the remaining components; the piezoelectric driver applies a driving force to the valve core assembly through an external voltage when the proportional valve is open; the valve core assembly seals the working medium flow channel when the proportional valve is closed; when the proportional valve is open, the driving force of the piezoelectric driver causes displacement, opening the working medium flow channel and changing its flow size, thereby changing the flow rate of the working medium flowing through the valve body assembly; the displacement measurement assembly measures the displacement of the valve core assembly and provides sealing force for the valve core assembly. The present invention directly measures the valve core of the piezoelectric proportional valve without introducing redundant materials or affecting reliability, further improving the response speed of flow control.

Description

Technical Field

[0001] The present invention relates to the technical field of proportional valves, and in particular to a valve core displacement direct-measurement piezoelectric proportional valve. Background Art

[0002] Piezoelectric-driven proportional valves and proportional thrusters are gaining increasing application in microfluidics applications such as aerospace, precision manufacturing, and healthcare, leading to increasingly stringent requirements for flow rate convergence speed. Piezoelectric actuators exhibit inherent characteristics such as hysteresis and creep. While their absolute magnitude is typically on the order of 10-100nm, the regulated flow rate is in the μg / s to mg / s range, and displacement changes at this level often result in flow rate variations exceeding 50%. Consequently, achieving high-precision displacement control through a single voltage output no longer meets performance requirements in terms of accuracy and convergence speed. Therefore, precise sensing and feedback of the displacement required for flow regulation are necessary to meet the requirements for rapid flow control.

[0003] Some existing displacement feedback methods usually use displacement feedback on the piezoelectric driver itself. This is essentially an indirect measurement and cannot accurately measure the actual opening degree that is most relevant to the flow rate - the valve core displacement. Since the valve core-valve seat sealing pair has elastic deformation and its opening voltage inevitably changes when the external temperature changes, it is impossible to accurately obtain information on the valve core displacement change.

[0004] Therefore, it is necessary to accurately and directly test the valve core displacement without introducing redundant objects and affecting reliability, so as to achieve the purpose of rapid flow regulation. Summary of the Invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology and provide a piezoelectric proportional valve with direct valve core displacement measurement, which directly measures the valve core displacement of the proportional valve without introducing redundant objects and without affecting reliability, thereby improving measurement accuracy and flow convergence speed.

[0006] The technical solution of the present invention is: a valve core displacement direct measurement type piezoelectric proportional valve, comprising a valve body assembly, a piezoelectric driver, a valve core assembly, and a displacement measurement assembly;

[0007] Valve body assembly: forming a working medium flow channel and installing the piezoelectric driver, valve core assembly and displacement measurement assembly;

[0008] Piezoelectric actuator: When the proportional valve is opened, it applies driving force to the valve core assembly through the drive of external voltage;

[0009] Valve core assembly: When the proportional valve is closed, it seals the working medium flow channel; when the proportional valve is opened, it produces displacement under the driving force of the piezoelectric actuator, opening the working medium flow channel and changing its flow size, thereby changing the flow rate of the working medium flowing through the valve body assembly;

[0010] Displacement measuring component: measures the displacement of the valve core component and provides sealing force for the valve core component.

[0011] Preferably, the valve body assembly includes a valve body, a drive chamber pressure cover and a sealing chamber pressure cover; one end of the valve body is a drive chamber, which is closed by the drive chamber pressure cover, and the other end is a sealing chamber, which is closed by the sealing chamber pressure cover. The drive chamber and the sealing chamber are connected by a connecting channel, and the piezoelectric driver is located in the drive chamber, with one end fixed on the drive chamber pressure cover.

[0012] Preferably, the displacement measuring assembly includes a displacement measuring stator, a displacement measuring mover and a sealing disc spring; the displacement measuring stator is fixed to the sealing chamber pressure cover and is located outside the sealing chamber; one end of the displacement measuring mover overlaps the valve core assembly, and the other end passes through the through hole provided on the sealing chamber pressure cover to pass out of the sealing chamber; the sealing disc spring is located between the displacement measuring mover and the sealing chamber pressure cover, and applies a force to the displacement measuring mover toward the driving chamber through deformation, thereby further applying a sealing force to the valve core assembly.

[0013] Preferably, the valve core assembly includes a push rod, a sealing seat and a ceramic ball, one end of the push rod is overlapped with the other end of the piezoelectric driver, and the other end passes through the connecting channel; the sealing seat is located in the sealing cavity, and a cavity matching the size of the ceramic ball is opened on the side facing the sealing cavity pressure cover, and a sealing channel connected to the connecting channel and the cavity is provided on the side of the sealing seat close to the connecting channel, and the ceramic ball arranged in the cavity is overlapped with one end of the displacement measuring mover; a preload disc spring is provided between the push rod and the end face of the drive cavity, which provides a preload force to the push rod away from the sealing cavity through deformation.

[0014] Preferably, under the action of the sealing force, the ceramic ball forms a sealing pair with the end surface of the sealing channel when the proportional valve is closed.

[0015] Preferably, when the proportional valve is closed, the distance between the other end of the push rod and the ceramic ball is 2 μm to 5 μm.

[0016] Preferably, the valve body is provided with an inlet flow channel and an outlet flow channel for the working medium. When the proportional valve is opened, the working medium flowing into the valve body through the inlet flow channel flows through the sealing channel and the connecting channel and then flows out of the valve body through the outlet flow channel. The directions of the inlet flow channel and the outlet flow channel are perpendicular to the direction of the working medium circulation channel.

[0017] Preferably, the change in the distance between the displacement measuring mover and the displacement measuring stator is equal to the change in the displacement of the push rod when the proportional valve is opened, and is linearly related to the increment of the driving voltage of the piezoelectric driver.

[0018] Preferably, a first seal is provided between the other end of the push rod and the connecting channel, a second seal is provided between the end face of the sealing seat close to the connecting channel and the end face of the sealing cavity, and a third seal is provided between the displacement measuring mover and the sealing cavity pressure cover. The first seal, the second seal or the third seal is an O-ring made of rubber material.

[0019] Preferably, the displacement measuring stator, the sealing chamber gland, the valve body and the displacement measuring mover are made of materials with similar thermal expansion coefficients.

[0020] The advantages of the present invention over the prior art are: the present invention directly measures the valve core displacement by arranging a displacement measuring component at the valve core displacement end of the piezoelectric proportional valve, thereby realizing direct measurement of the actual opening of the valve body working medium flow channel, avoiding the problem that the valve core-valve seat sealing pair has elastic deformation and its opening voltage inevitably changes when the external temperature changes, and it is difficult to accurately obtain the valve core displacement change information and thus it is difficult to accurately establish a flow model; at the same time, the structure can conveniently realize the rapid convergence of the flow rate, and solve the problem of the corresponding relationship between the actual valve core displacement and the flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of a piezoelectric proportional valve with direct valve core displacement measurement according to the present invention;

[0022] Figure 2 This is a schematic diagram of the working medium flow channel structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of the displacement measurement component of the present invention. DETAILED DESCRIPTION

[0024] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0025] A piezoelectric proportional valve with direct valve core displacement measurement, the structure of which is as follows Figure 1 As shown, it includes a valve body assembly, a piezoelectric driver 12, a valve core assembly, and a displacement measurement assembly.

[0026] The valve body assembly includes a valve body 13, a drive chamber pressure cover 14 and a sealing chamber pressure cover 4. One end of the valve body 13 is provided with a drive chamber, and the other end is provided with a sealing chamber. The drive chamber and the sealing chamber are connected by a connecting channel.

[0027] Specifically, the driving chamber pressure cover 14 is fixed to the end of the driving chamber to seal the driving chamber; the sealing chamber pressure cover 4 is fixed to the end surface of the sealing chamber of the valve body 13 to seal the sealing chamber.

[0028] The piezoelectric driver 12 is located in the driving cavity. One end of the piezoelectric driver 12 is fixedly connected to the driving cavity pressure cover 14, and is fixed and limited by the driving cavity pressure cover 14. The other end is overlapped with one end of the push rod 11. At the same time, a groove is opened on the side wall of the driving cavity to lead out the lead of the piezoelectric driver 12. The piezoelectric driver 12 receives external voltage through the lead to generate deformation, and further drives the valve core assembly to generate displacement.

[0029] like Figure 2 As shown, the displacement measuring assembly includes a displacement measuring stator 1, a displacement measuring mover 2, a mover O-ring, a sealing chamber pressure cover 4 and a sealing disc spring 5.

[0030] The displacement measuring assembly includes a pressure cover including a displacement measuring stator 1, a displacement measuring mover 2 and a sealing disc spring 5; the displacement measuring stator 1 is fixed to the sealing chamber pressure cover 4 and is located outside the sealing chamber. The sealing chamber pressure cover 4 has a through hole in the axial direction. One end of the displacement measuring mover 2 is located in the sealing chamber, and the other end extends out of the sealing chamber through the through hole and can move along the direction of the through hole. One end of the sealing disc spring 5 overlaps with the displacement measuring mover 2, and the other end overlaps with the sealing chamber pressure cover 4. Through deformation, it provides an axial sealing force toward the driving chamber for the displacement measuring mover 2, and further provides sealing force for the valve core assembly. By controlling the deformation amount of the sealing disc spring 5, different sealing forces can be provided.

[0031] Specifically, a groove is formed on the side wall of the through hole of the sealing cavity gland 4 , and a sensor measuring mover O-ring 3 is arranged in the groove for sealing the sealing cavity.

[0032] Furthermore, the displacement measuring stator 1 can be a composite structure of different materials such as a light source or ceramics according to different distance measuring principles. The distance between the displacement measuring stator 1 and the displacement measuring mover 2 is measured by a corresponding distance measuring sensor, such as a capacitive displacement sensor or a laser displacement sensor.

[0033] The valve core assembly is located in the sealing chamber, and includes a push rod 11, a sealing seat 7 and a ceramic ball 6; one end of the push rod 11 overlaps with the piezoelectric driver 12, and a part of the other end is located in the connecting channel, and moves along the direction of the connecting channel under the action of the piezoelectric driver 12. The sealing seat 7 is installed in the sealing chamber, and the side of the sealing seat 7 close to the connecting channel is provided with a sealing channel connected to the connecting channel to accommodate the movement of the end of the push rod 11, and the side away from the connecting channel is provided with a cavity to accommodate the movement of the ceramic ball 6. The size of the cavity matches the ceramic ball 6 and has a guiding function. One end of the ceramic ball 6 overlaps with the displacement measuring actuator 2. In the initial state, the ceramic ball 6 contacts the end face of the sealing channel of the sealing seat 7 under the action of the axial compression force transmitted by the displacement measuring actuator 2 to form a metal sealing pair, which is in a normally closed state.

[0034] Specifically, the material of the ceramic balls 6 is hard ceramic.

[0035] Specifically, a preload disc spring 10 is provided between the push rod 11 and the step surface of the driving chamber. The preload disc spring 10 provides an axial preload force away from the sealing chamber to the push rod 11 through deformation, and further transmits the preload force to the piezoelectric driver 12.

[0036] Furthermore, a groove is provided on the portion of the push rod 11 located in the connecting channel, and an O-ring 9 for sealing is installed in the groove to seal the driving cavity.

[0037] Furthermore, the displacement measuring mover 2 and the ceramic ball are a flat-plate direct-push structure, which utilizes the self-centering characteristics of the ceramic ball 6, thereby reducing the requirements for processing accuracy; the contact end of the displacement measuring mover 2 and the ceramic ball 6 is provided with a groove matching the ceramic ball 6, and the surface is cold-worked and hardened or the material is heat-treated to improve the hardness and structural stability of the displacement measuring mover 2.

[0038] Furthermore, the flow path of the working medium in the valve core displacement direct measurement type piezoelectric proportional valve of the present invention is as follows: Figure 3 As shown, the actuator valve body 13 is provided with an inlet flow channel, an outlet flow channel, and a circulation channel for the working medium. The inlet flow channel is provided on the side wall of the sealing cavity, and the outlet flow channel is provided on the side wall of the connecting channel. The directions of the inlet and outlet flow channels are perpendicular to the axial direction of the valve body. The working medium flows into the valve body from the inlet channel. When the valve is opened, it flows into the connecting channel through the sealing channel of the sealing seat and then flows out of the valve body through the outlet flow channel. In the initial state, the ceramic ball 6 is in a normally closed state due to the force generated by the deformation of the sealing disc spring 5. The sealing seat 7 has an annular groove on its end face near the connecting channel. The sealing seat O-ring 8 is placed in the annular groove to seal the sealing seat and the connecting channel, isolating the inlet flow channel from the outlet flow channel, thereby ensuring that the above-mentioned fluid channel is the only fluid channel.

[0039] Furthermore, the displacement measuring mover 2, the sealing chamber gland 4, the sealing disc spring 5, the sealing seat 7, the preload disc spring 10, the ejector rod 11, the actuator valve body 13, and the drive chamber gland 14 are constructed of metal. Specifically, the displacement measuring stator 1, the sealing chamber gland 4, the actuator valve body 13, and the displacement measuring mover 2 are constructed of materials with similar thermal expansion coefficients.

[0040] The mover O-ring, the sealing seat O-ring 8 and the driving rod O-ring 9 are made of rubber and a series of composite materials derived from rubber.

[0041] The assembly process of the valve core displacement direct measurement piezoelectric proportional valve of the present invention is as follows:

[0042] First, install the sealing seat O-ring 8 into the groove of the sealing seat 7. Place the sealing seat 7 into the sealing cavity of the actuator valve body 13. Then, place the ceramic ball 6 into the inner cavity of the sealing seat 7 and the actuator O-ring into the groove of the sealing cavity gland 4. Next, install the displacement measuring actuator 2, the sealing disc spring 5, and the sealing cavity gland 4 into the sealing cavity of the actuator valve body 13. Adjust the sealing cavity gland 4 to squeeze the sealing disc spring 5 to produce an appropriate deformation, providing preload force for the displacement measuring actuator 2. This further provides the required sealing force for the ceramic ball 6, causing it to contact the sealing opening of the sealing seat 7 to form a sealing pair and form a reliable seal. Under the action of the sealing force, the ceramic ball 6 is in a normally closed state. After the sealing cavity gland 4 and the actuator valve body 13 compress the sealing disc spring 5, they are tightened by welding or screwing, thus completing the assembly of the sealing end.

[0043] Install the drive rod O-ring 9 into the groove of the push rod 11, and then place the preload disc spring 10, the assembly of the drive rod O-ring 9 and the push rod 11, the piezoelectric driver 12 and the drive cavity pressure cover 14 into the drive cavity of the driver valve body 13 in sequence. The drive cavity pressure cover 14 and the driver valve body 13 are fastened together by threads or welding to control the deformation of the preload disc spring 10 to the required value. At the same time, it also drives the push rod 11 through the connecting channel in the driver valve body 13 to approach the ceramic ball 6, so that the distance between the two is about 2μm to 20μm.

[0044] When adjusting the displacement measuring stator 1, first measure the output distance when the drive rod O-ring 9, driver valve body 13, preload disc spring 10, push rod 11, piezoelectric driver 12 and drive chamber pressure cover 14 are assembled together during the idle stroke, and then assemble the entire proportional valve together to ensure that the distance between the displacement measuring stator 1 and the displacement measuring mover 2 is 1~1.2 times the output distance. At this time, apply the maximum working voltage to the piezoelectric driver under the highest and lowest temperature conditions within the high and low temperature range required by the product to ensure that the minimum distance between the displacement measuring stator 1 and the displacement measuring mover 2 is between 2μm and 10μm.

[0045] The process of using the valve core displacement direct measurement piezoelectric proportional valve of the present invention is as follows:

[0046] When the piezoelectric driver 12 is not powered, the distance between the displacement measuring stator 1 and the displacement measuring mover 2 is the initial distance; when the piezoelectric driver 12 is powered, the distance between the displacement measuring stator 1 and the displacement measuring mover 2 changes.

[0047] During operation, a driving voltage is applied to the piezoelectric driver 12, causing the piezoelectric driver 12 to deform axially, driving the push rod 11 toward the ceramic ball 6. After the push rod 11 contacts the ceramic ball 6, it overcomes the sealing force applied to the ceramic ball 6 by the sealing disc spring 5 and pushes the ceramic ball 6 open. The ceramic ball 6 is pressed tightly into the groove on the displacement measuring mover 2, pushing the displacement measuring mover 2 to move and transmitting the displacement of the push rod 11. The change in distance between the displacement measuring stator 1 and the displacement measuring mover 2 is the flow channel opening height. The distance between the displacement measuring stator 1 and the displacement measuring mover 2 is measured by a distance measuring sensor. When the distance between the displacement measuring stator 1 and the displacement measuring mover 2 changes, the electrical signal output by the distance measuring sensor also changes accordingly. By processing the output electrical signal, direct measurement of the flow channel opening height can be achieved. To ensure a reliable seal, there is a gap between the ceramic ball 6 and the end of the push rod 11, typically 2 to 20 μm. Therefore, when voltage is initially applied to the piezoelectric actuator 12, the distance between the displacement measuring stator 1 and the displacement measuring mover 2 remains unchanged. Once the push rod 11 pushes the ceramic ball 6 away, the voltage increment applied to the piezoelectric actuator 12 and the distance between the displacement measuring stator 1 and the displacement measuring mover 2 become linearly related. When the proportional valve is closed, the voltage applied to the piezoelectric actuator 12 decreases, and the push rod 11, under the action of the preload disc spring 10, disengages from the ceramic ball 6. The sealing disc spring 5 presses the ceramic ball 6 against the sealing opening of the actuator valve body 13, achieving a seal. At this point, as the voltage applied to the piezoelectric actuator 12 continues to decrease, the distance between the displacement measuring stator 1 and the displacement measuring mover 2 remains unchanged, returning to its initial, unpowered state.

[0048] The valve core displacement direct measurement piezoelectric proportional valve provided by the present invention is suitable for high-precision, high-resolution, micro-flow fluid control systems with fast response requirements; such as high-precision proportional control of next-generation drag-free spacecraft, micro-flow controllers in the biochemical field, etc., and can meet their requirements for response speed and accuracy.

[0049] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A piezoelectric proportional valve with direct valve core displacement measurement, characterized in that: It includes a valve body assembly, a piezoelectric driver (12), a valve core assembly, and a displacement measurement assembly; Valve body assembly: forming a working medium flow channel and mounting the piezoelectric driver (12), valve core assembly and displacement measurement assembly; Piezoelectric driver (12): When the proportional valve is opened, it applies driving force to the valve core assembly through the drive of external voltage; The valve core assembly: when the proportional valve is closed, the working medium flow channel is sealed; when the proportional valve is opened, the proportional valve is displaced under the driving force of the piezoelectric driver (12), thereby opening the working medium flow channel and changing its flow size, thereby changing the flow rate of the working medium flowing through the valve body assembly; Displacement measuring assembly: measuring the displacement of the valve core assembly and providing sealing force for the valve core assembly; The valve body assembly comprises a valve body (13), a drive chamber pressure cover (14) and a sealing chamber pressure cover (4); one end of the valve body (13) is a drive chamber, which is closed by the drive chamber pressure cover (14), and the other end is a sealing chamber, which is closed by the sealing chamber pressure cover (4); the drive chamber and the sealing chamber are connected via a connecting channel, and the piezoelectric driver (12) is located in the drive chamber, and one end is fixed to the drive chamber pressure cover (14); The displacement measuring assembly comprises a displacement measuring stator (1), a displacement measuring mover (2) and a sealing disc spring (5); the displacement measuring stator (1) is fixed to the sealing chamber pressure cover (4) and is located outside the sealing chamber; one end of the displacement measuring mover (2) is overlapped with the valve core assembly, and the other end passes through a through hole provided on the sealing chamber pressure cover (4) and out of the sealing chamber; the sealing disc spring (5) is located between the displacement measuring mover (2) and the sealing chamber pressure cover (4), and exerts a force on the displacement measuring mover (2) in the direction of the driving chamber through deformation, thereby further exerting a sealing force on the valve core assembly; The valve core assembly includes a push rod (11), a sealing seat (7) and a ceramic ball (6), one end of the push rod (11) is overlapped with the other end of the piezoelectric driver (12), and the other end passes through the connecting channel; the sealing seat (7) is located in the sealing cavity, and a cavity matching the size of the ceramic ball (6) is opened on the side facing the sealing cavity pressure cover (4); a sealing channel connected to the connecting channel and the cavity is provided on the side of the sealing seat (7) close to the connecting channel, and the ceramic ball (6) arranged in the cavity is overlapped with one end of the displacement measuring mover (2); a preload disc spring (10) is provided between the push rod (11) and the end face of the driving cavity, which provides a preload force for the push rod (11) away from the sealing cavity through deformation; When the proportional valve is closed, the distance between the end of the other end of the push rod (11) and the ceramic ball (6) is 2 μm to 5 μm; A groove is provided on a surface of the sealing seat (7) facing the ceramic ball (6), and the ceramic ball (6) is located in the groove; the plane of the displacement measuring mover (2) contacts the ceramic ball (6).

2. A piezoelectric proportional valve with direct valve core displacement measurement according to claim 1, characterized in that: Under the action of the sealing force, the ceramic ball (6) forms a sealing pair with the end face of the sealing channel when the proportional valve is closed.

3. The piezoelectric proportional valve with direct valve core displacement measurement according to claim 1, characterized in that: The valve body (13) is provided with an inlet flow channel and an outlet flow channel for the working medium. When the proportional valve is opened, the working medium flowing into the valve body (13) through the inlet flow channel flows through the sealing channel and the connecting channel and then flows out of the valve body (13) through the outlet flow channel. The directions of the inlet flow channel and the outlet flow channel are perpendicular to the direction of the working medium circulation channel.

4. A piezoelectric proportional valve with direct valve core displacement measurement according to claim 3, characterized in that: The change in distance between the displacement measuring mover (2) and the displacement measuring stator (1) is equal to the change in displacement of the push rod (11) when the proportional valve is opened, and is linearly related to the increment of the driving voltage of the piezoelectric driver (12).

5. A piezoelectric proportional valve with direct valve core displacement measurement according to any one of claims 2 to 4, characterized in that: A first sealing member (9) is provided between the other end of the push rod (11) and the connecting channel, a second sealing member (8) is provided between the end face of the sealing seat (7) close to the connecting channel and the end face of the sealing cavity, and a third sealing member (3) is provided between the displacement measuring mover (2) and the sealing cavity pressure cover (4), wherein the first sealing member (9), the second sealing member (8) or the third sealing member (3) is an O-ring made of rubber material.

6. A piezoelectric proportional valve with direct valve core displacement measurement according to claim 5, characterized in that: The displacement measuring stator (1), the sealing chamber pressure cover (4), the valve body (13) and the displacement measuring mover (2) are made of materials with similar thermal expansion coefficients.

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