Proportional valve structure with flow not affected by pressure difference of inlet and outlet

Abstract

The utility model discloses a proportional valve structure with flow not affected by pressure difference of an inlet and an outlet, which comprises a valve body used for forming a fluid channel. The valve port is arranged in the valve body, and the valve element assembly comprises a movable iron core, a sealing piece and an elastic feedback element and is used for adjusting the opening degree of the valve port; the driving device comprises a static iron core, a coil and a magnetic conductive component, and the coil is used for generating electromagnetic force to drive the movable iron core to move; the pressure difference feedback mechanism comprises a diaphragm and a ventilation structure, the diaphragm is arranged between the valve element assembly and the fluid channel, the ventilation structure is used for guiding fluid in the fluid channel into the position above the diaphragm to form feedback force related to the pressure difference of a fluid inlet and a fluid outlet, and the feedback force acts on the valve element assembly; the opening degree of the valve port is automatically adjusted according to changes of inlet and outlet pressure difference so as to stabilize fluid flow. The valve is simple in structure, the opening degree of the valve port can be adjusted through feedback of the pressure difference of the inlet and the outlet without additional flow detection for closed-loop control, and therefore the flow is stabilized within a certain range.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of fluid proportional valve, and relates to a proportional valve structure not affected by inlet and outlet pressure difference. BACKGROUND

[0002] As a basic fluid control component, the fluid proportional regulating valve has the characteristics of stepless adjustment, high precision and fast response, and is widely used in many fields such as industrial automation, aerospace, medical devices and scientific instruments, and can realize rapid and continuous regulation and control of flow and pressure.

[0003] The valve core of the fluid proportional valve is driven by a proportional electromagnet, and the valve port opening is changed by changing the displacement of the valve core. The outlet flow of the fluid proportional valve is not only related to the valve port opening, but also closely related to the inlet and outlet pressure difference. When the inlet and outlet pressure difference changes, even if the valve port opening does not change, the flow will also change.

[0004] In the application of the fluid proportional valve, the flow often needs to be adjusted and controlled. In some working conditions, the pressure difference before and after the fluid proportional valve is prone to fluctuation, causing flow changes. In order to ensure constant output flow, a flowmeter is often introduced for flow detection, and closed-loop control is performed to adjust the opening of the fluid proportional valve in real time. At present, there is no fluid proportional valve structure on the market that can adjust according to the pressure difference feedback to ensure stable output flow. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a proportional valve structure not affected by inlet and outlet pressure difference to solve the problems raised in the above background.

[0006] The utility model comprises:

[0007] A valve body for forming a fluid passage;

[0008] A valve port provided in the valve body for controlling the on-off and flow rate of fluid;

[0009] A valve core assembly comprising a moving iron core, a sealing element and an elastic feedback element, the moving iron core being connected with the sealing element for adjusting the valve port opening;

[0010] A driving device comprising a static iron core, a coil and a magnetic conducting part, the static iron core cooperating with the moving iron core, and the coil being used to generate electromagnetic force to drive the moving iron core to move;

[0011] A pressure difference feedback mechanism comprising a diaphragm and a vent structure, the diaphragm being arranged between the valve core assembly and the fluid passage, and the vent structure being used to introduce fluid in the fluid passage above the diaphragm to form a feedback force related to the inlet and outlet pressure difference of the fluid, the feedback force acting on the valve core assembly for automatically adjusting the valve port opening according to the change of the inlet and outlet pressure difference to stabilize the fluid flow.

[0012] The utility model has the advantages of the following:

[0013] 1. The utility model can feedback regulation opening according to the pressure difference of entrance and exit, realize flow stability.

[0014] 2. The utility model has simple structure, low cost, need not introduce flow measurement to carry out closed loop control, can realize flow stability.

[0015] 3. The utility model utilizes entrance air pressure to carry out sealing, can reduce the pre-pressure of spring, thereby reducing the impact of spring force on valve port sealing element when fluid proportional valve frequently works, improves service life. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is the structural schematic diagram of the embodiment of the application.

[0017] Figure 2 It is the laser welding schematic diagram of static iron core and support pipe of the embodiment of the application.

[0018] Figure 3 It is the reed structure schematic diagram of the embodiment of the application.

[0019] Figure 4 It is the installation explosion drawing of the embodiment of the application.

[0020] Figure 5 It is the internal fluid flow direction schematic diagram of the embodiment of the application.

[0021] Figure 6 It is the diaphragm structure schematic diagram of the embodiment of the application.

[0022] Figure 7 It is the force analysis diagram of valve core system of the embodiment of the application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present disclosure more clear, the following will be further described in detail in combination with specific embodiments and with reference to the drawings.

[0024] In the embodiment of the present disclosure, the fluid proportional valve structure is as shown in Figure 1 The main components are valve body 1, valve port 2, reed 3, reed pressing plate 4, diaphragm 5, support pipe 6, magnetically conductive shell 7, static iron core 8, dynamic iron core 9, spring 10, coil 11, magnetically conductive bottom plate 12, valve port sealing element 13 and bolt 14.

[0025] Valve body 1 is made by casting process, the material can choose brass or stainless steel, valve body 1 is connected with valve port 2 by interference fit, and sealing glue can be applied during connection to ensure sealing, considering that the pressure range and flow range of fluid proportional valve are closely related to the diameter of valve port, valve body 1 can be combined with valve port 2 of different diameter to form different diameter combinations, so as to adapt to different pressure and flow use scenarios, and increase the use flexibility of fluid proportional valve.

[0026] Valve core system is composed of moving core 9, diaphragm 5, reed 3 and valve port seal 13, the bottom of valve port seal 13 is formed into a rubber part by vulcanization process, and is pre-pressed on valve port 2 by top spring 10 to realize sealing. Static core 8 adopts the scheme of disc type electromagnet, which is provided with two taper angles at the basin port, can provide large output force in a short stroke range, thereby reducing the power consumption of electromagnet, and the structure parameters can be optimized by magnetic field simulation software to realize optimal design.

[0027] Static core 8 is connected with support pipe 6 by laser welding, as shown in Figure 2 , which ensures reliable support connection while requiring sealing at the weld, without leakage. Moving core 9 and valve port seal 13 are connected by threads, with reed 3 and diaphragm 5 installed in the middle, and radial support is provided by reed 3, which is composed of stainless steel material and has special profile by laser etching, as shown in Figure 3 , so as to ensure the radial support stiffness and prevent the moving core 9 from contacting and colliding with support pipe 6 during movement, thereby increasing the hysteresis of fluid proportional valve.

[0028] The inside of fluid proportional valve is sealed by diaphragm 5 and feedback adjustment is performed, and reed 3 is fixed on the step inside valve body 1 by reed pressing plate 4. Coil 11 is composed of a certain number of turns of enameled wire wound on the coil skeleton, and the lead wire is led out through the lead hole on magnetic conductive shell 7, when the coil 11 is energized, the coil 11 generates a magnetic field, and a closed magnetic circuit is formed by moving core 9, static core 8, magnetic conductive shell 7 and magnetic conductive bottom plate 12, and the electromagnetic force proportional to the current can be applied to moving core 9. Moving core 9, static core 8, magnetic conductive shell 7 and magnetic conductive bottom plate 12 can be made of pure iron material, which has high magnetic permeability, low coercive force, low hysteresis loss and high saturation magnetic induction intensity, etc. Excellent magnetism can improve electromagnetic force and reduce power consumption.

[0029] The installation schematic explosion diagram of fluid proportional valve is as shown in Figure 4As shown, the installation process is as follows: first, the valve body 1 and the valve port 2 are combined by interference connection to form a valve body assembly, the coil 11 is bonded to the magnetic bottom plate 12 and is sleeved into the support pipe 6, then the static iron core 9 is laser welded with the support pipe 6 to form a static iron core assembly, then the dynamic iron core 9, diaphragm 5, reed 3 and valve port seal 13 are combined, the diaphragm 5 and reed 3 are compressed by threaded connection, forming a dynamic iron core assembly, the valve core system is placed at the step of the valve body 1, the reed pressing plate 4 is placed on the reed 3, the spring 10 is placed into the step of the dynamic iron core 9, and then the laser welded static iron core assembly is placed, the valve body assembly, static iron core assembly and dynamic iron core assembly are connected by bolts 14, and finally the magnetic shell 11 is sleeved, and the magnetic shell 11 and the magnetic bottom plate 12 are laser welded.

[0030] As shown, when the fluid flows through the valve body 1 from the inlet, Figure 5 a part of it is divided by the valve body and enters the upper chamber through the diaphragm vent groove flow passage, the pressure of the upper chamber can be considered consistent with the inlet pressure, and the other part flows to the outlet through the valve port nozzle. It can be seen that the fluid is throttled and reduced in pressure at the valve port nozzle, and then does not pass through the related throttling and reducing structure, so it can be considered that the average pressure in the valve chamber is consistent with the outlet pressure. Therefore, the upper part of the diaphragm 5 is under the inlet pressure and the lower part is under the outlet pressure, and the diaphragm 5 has a certain elasticity and can obviously be affected by the pressure difference between the upper and lower parts to adjust. The structure of the diaphragm 5 is shown in Figure 6 , which has a vent groove on one side to introduce the inlet fluid into the upper part of the diaphragm 5 and seal the gas chamber above the diaphragm 5 from the outside. The diaphragm 5, dynamic iron core 9, valve port seal 13 and reed 3 form a valve core system. The diaphragm 5 is made of rubber material and has high-strength fiber cloth embedded inside. The fiber cloth is polyester fiber or nylon. In order to increase the strength and pressure resistance, the embodiment adds a composite material of nylon cloth inside the rubber diaphragm.

[0031] The working principle of the embodiment is described as follows:

[0032] As shown in Figure 1 , when the coil is not powered, the pre-pressure of the spring 10 and the air pressure of the upper chamber tightly press the valve core assembly against the valve seat, and the rubber part at the valve port seal 13 realizes sealing. When the supply current of the coil 11 is gradually increased, the electromagnetic force acting on the dynamic iron core 9 is gradually increased. When the upward resultant force acting on the valve core system exceeds the downward resultant force, the valve port is opened, and the fluid flows through the valve port to generate flow. At this time, due to the proportional output characteristic of the proportional valve electromagnet, the electromagnetic force is linearly related to the current, resulting in that the valve opening degree is linearly related to the current. When the inlet and outlet pressure difference does not change, the valve opening degree is fixed when the supply current is fixed, and the outlet flow is fixed.

[0033] When the inlet pressure increases and the outlet pressure remains unchanged, the air pressure on the diaphragm 5 increases, which will inevitably cause the spool to move in the direction of reducing the opening, thereby hindering the increase of the flow caused by the increase of the pressure difference between the inlet and outlet. Conversely, when the inlet pressure remains unchanged and the outlet pressure increases, the air pressure on the diaphragm 5 decreases, which will inevitably cause the spool to move in the direction of increasing the opening, thereby hindering the decrease of the flow caused by the decrease of the pressure difference between the inlet and outlet. For the case where the pressure difference between the inlet and outlet decreases, the same conclusion can be drawn that the change in the opening of the valve port caused by the air pressure will be opposite to the change in the flow, thereby preventing the change in the flow and balancing the influence of the pressure difference between the inlet and outlet.

[0034] The force analysis of the spool system is as follows, as shown in Figure 7 , which is subjected to fluid impact force, electromagnetic force, spring force, feedback force and gravity, and is balanced under the action of these forces.

[0035] mg+F b +F0+kx=F e +F g

[0036] x=(F e +F g -△P·S-F0-mg) / k

[0037] In the formula, m is the mass of the moving iron core assembly, F b is the feedback force, F b =△P·S, S is the force area of the diaphragm, △P is the pressure difference between the inlet and outlet, F0 is the spring pre-pressure, the initial pre-pressure of the diaphragm can be ignored, k is the superimposed axial stiffness of the diaphragm and spring, F e is the electromagnetic force, F g is the fluid impact force, and x is the displacement opening of the spool.

[0038] For a valve port with a diameter of D, the flow area at an opening x is A=πDx, the valve port orifice can be considered as a thin-walled small hole, when the flow rate is small, the influence of compressibility is ignored, and the flow through the orifice can be calculated by the following formula

[0039]

[0040] In the formula, q m is the mass flow, unit kg / s, C d is the flow coefficient, A is the flow area, unit m 2 , and ρ is the fluid density;

[0041]

[0042] Considering the case where the pressure difference between the inlet and outlet remains unchanged, F eThe electromagnetic force can be considered as a linear function of the current I, and according to the calculation formula, the electromagnetic force increases with the increase of the current, when the electromagnetic force is insufficient to offset the spring force and the gravity, the spool does not produce displacement, when the electromagnetic force increases beyond the critical value, the spool starts to produce displacement, because the output electromagnetic force of the proportional electromagnet is proportional to the current, the last output flow is proportional to the current.

[0043] When the inlet and outlet pressure difference changes, it is intuitively understood that when the pressure difference increases, if the spool opening does not change, the flow will inevitably increase, however, the feedback force increases will cause the spool opening to decrease, to a certain extent, offset the influence of the increase of the pressure difference, and vice versa. The following will be further explained in combination with mathematical formula, the above calculation formula is simplified as:

[0044]

[0045] C2 = △P S

[0046] q m = C1△P 1 / 2 -C2△P 3 / 2

[0047] Derivation:

[0048]

[0049] Function extreme point:

[0050] Substitute the extreme point into the original function to obtain:

[0051]

[0052] The function image trend is first rising from the image origin, then falling after reaching the extreme point, the overall shape is first convex and then concave, obviously, near the extreme point, with the increase or decrease of the pressure difference, the flow will decrease. Through the calculation formula, the working pressure difference interval can be flexibly selected, the extreme point can be included or not included, the parameters are adjusted, the change rate of the flow with the pressure difference in the working interval is reduced, so that the outlet flow fluctuation is controlled in an acceptable range, so as to stabilize the flow.

[0053] The above are preferred embodiments of the present application, and are not limited to the protection scope of the present application, therefore: all equivalent changes made according to the structure, shape, principle of the present application shall be covered in the protection scope of the present application

[0054] Finally, it should be noted that the above list is the near utility model of several specific embodiments. Obviously, the utility model is not limited to the above examples, but can have many variations. All variations that can be directly derived or inferred from the utility model disclosed by the ordinary skilled in the art should be considered as the protection scope of the utility model.

Claims

1. A proportional valve structure whose flow rate is unaffected by the inlet and outlet pressure difference, characterized in that, include: Valve body (1) is used to form a fluid passage; The valve port (2) is located inside the valve body (1) and is used to control the flow rate and the on / off state of the fluid. The valve core assembly includes a moving iron core (9), a seal (13), and an elastic feedback element. The moving iron core (9) is connected to the seal (13) and is used to adjust the valve opening. The driving device includes a stationary iron core (8), a coil (11) and a magnetic conductive component. The stationary iron core (8) cooperates with the moving iron core (9). The coil (11) is used to generate electromagnetic force to drive the moving iron core (9) to move. The differential pressure feedback mechanism includes a diaphragm (5) and a venting structure. The diaphragm (5) is disposed between the valve core assembly and the fluid channel. The venting structure is used to introduce fluid from the fluid channel above the diaphragm (5) to form a feedback force related to the pressure difference between the fluid inlet and outlet. The feedback force acts on the valve core assembly to automatically adjust the valve opening according to the change in the pressure difference between the inlet and outlet, so as to stabilize the fluid flow rate.

2. The proportional valve structure according to claim 1, wherein the flow rate is unaffected by the inlet / outlet pressure difference, is characterized in that, The elastic feedback element includes a reed (3) and a spring (10). The reed (3) is made of stainless steel and is formed by laser etching to provide radial support and prevent the moving iron core (9) from contacting the support tube (6) and generating friction during movement.

3. The proportional valve structure according to claim 1, wherein the flow rate is unaffected by the inlet / outlet pressure difference, is characterized in that, The diaphragm (5) of the differential pressure feedback mechanism is made of rubber material and has a high-strength fiber fabric embedded inside. The fiber fabric is polyester fiber or nylon, which is used to increase the strength and pressure resistance of the diaphragm.

4. A proportional valve structure according to claim 1 or 3, wherein the flow rate is unaffected by the inlet / outlet pressure difference, characterized in that, The ventilation structure includes a ventilation groove disposed on the diaphragm (5). The ventilation groove is used to introduce the fluid at the inlet into the upper chamber above the diaphragm, so that the pressure in the upper chamber is consistent with the inlet pressure, and the pressure below the diaphragm is consistent with the outlet pressure, thereby realizing differential pressure feedback regulation through the elastic deformation of the diaphragm.

5. The proportional valve structure according to claim 1, wherein the flow rate is unaffected by the inlet / outlet pressure difference, is characterized in that, The drive device also includes a magnetic housing (7) and a magnetic base plate (12), which are made of electrical pure iron material to enhance electromagnetic force and reduce power consumption.

6. A proportional valve structure according to claim 1 or 5, characterized in that, The stationary iron core (8) adopts a disc electromagnet design with a cone-shaped structure at its rim, which can provide a large output force within a short stroke range, thereby reducing the power consumption of the electromagnet.

7. The proportional valve structure according to claim 1, wherein the flow rate is unaffected by the inlet / outlet pressure difference, is characterized in that, The valve body (1) and the valve port (2) are connected by an interference fit, and sealant is applied to the connection to ensure sealing. The valve body (1) can be matched with valve ports (2) of different diameters to adapt to different pressure and flow requirements.

8. The proportional valve structure according to claim 7, wherein the flow rate is unaffected by the inlet and outlet pressure difference, is characterized in that, The valve core assembly also includes a spring plate (4), which is used to fix the spring (3) and install it on the internal step of the valve body (1).

9. The proportional valve structure according to claim 1, wherein the flow rate is unaffected by the inlet / outlet pressure difference, is characterized in that, The bottom of the sealing element (13) is a rubber part, which is pressed against the valve port (2) under the pre-pressure of the spring (10) to achieve a seal.

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