JP4456352B2 - Motor driven proportional valve - Google Patents

Description

  The present invention relates to a motor-driven proportional valve that adjusts a valve opening degree by a motor.

  In recent years, fuel cells are attracting attention as clean power generators that generate electricity by reverse reaction of electrolysis using hydrogen and oxygen and have no emissions other than water. In fuel cells, many flow control valves are used for reformed gas, air pipes, etc., and motor-driven proportional valves are used as the flow control valves.

FIG. 7 is a cross-sectional view showing an example of a conventional motor-driven proportional valve 100.
The motor-driven proportional valve 100 is provided with a valve seat 103 between an input port 101 and an output port 102, and a valve body 104 comes into contact with or separates from the valve seat 103. The valve body 104 is connected to a motor 106 through a rod 105. The motor 106 rotatably holds the lead screw portion 107, and a female screw is formed in the lead screw portion 107. The rod 105 is configured such that a male screw formed on the outer peripheral surface is screwed into a female screw of the lead screw portion 107 and linearly moves in the vertical direction in accordance with the rotation of the lead screw portion 107.

  In such a motor-driven proportional valve 100, when the motor 106 rotates in the forward direction, the rod 105 rises to separate the valve body 104 from the valve seat 103, and when the motor 106 rotates in the reverse direction, the rod 105 descends. The valve body 104 is brought into contact with the valve seat 103. Therefore, the motor-driven proportional valve 100 can adjust the flow rate by arbitrarily setting the valve opening degree by controlling the rotation angle of the motor 106 (see, for example, Patent Document 1).

JP 2000-97359 A (pages 3 to 5, FIG. 1).

However, the conventional motor driven proportional valve 100 has the following problems.
(1) The motor-driven proportional valve 100 has an unstable hysteresis width and sometimes cannot accurately adjust the flow rate. Specifically, the motor-driven proportional valve 100 has, for example, a gap in the screw portion between the lead screw portion 107 and the rod 105, and when the motor 106 reverses the rotation direction, the rotational force is supplied from the lead screw portion 107. There is time that cannot be transmitted to the valve rod 105. For this reason, the motor-driven proportional valve 100 generates hysteresis between when the valve is opened and when the valve is closed. The hysteresis width is conventionally considered to be constant, and the motor-driven proportional valve 100 rotates the motor 106 in the reverse direction by a certain hysteresis width, for example, when the valve opening degree is controlled from open to closed. Thereafter, the motor 106 was rotated in the reverse direction by the rotation angle corresponding to the target flow rate.

  On the other hand, as a result of analysis of the hysteresis width by the inventors, it has been found that the hysteresis width is not constant. This is considered to be caused by a frictional resistance generated in the motor 106 or a processing failure of parts. Therefore, if the motor-driven proportional valve 100 is controlled on the assumption of a certain hysteresis width, for example, when the actual hysteresis width is larger than the predetermined hysteresis width, the motor 106 is rotated by the predetermined hysteresis width. Further, even if the motor 106 is rotated by the rotation angle corresponding to the target flow rate, the valve opening degree cannot be accurately controlled, and the flow rate may not be adjusted to the target flow rate.

(2) Further, the motor-driven proportional valve 100 has, as shown in FIG. 9, due to dimensional tolerances and assembly tolerances of components, from a rotation start position at which the motor 106 starts to rotate to origin positions G1 and G2 at which the valve starts to open. The amount of rotation may vary from product to product. On the other hand, the motor-driven proportional valve 100 controls the amount of rotation of the motor 106 by a driver (not shown) to adjust the valve opening. The driver stores in advance the origin position at which the valve starts to open, and controls the motor 106 on the assumption that the origin position of the motor-driven proportional valve 100 matches the previously stored origin position. Therefore, the motor-driven proportional valve 100 controls the motor 106 without recognizing the origin position at which the valve of the product starts to open, and if the origin position of the product is deviated from the origin position of the driver, the origin search is performed. It was not performed accurately, and the valve opening could not be adjusted so that the flow rate was adjusted to the target value only by the rotation angle of the motor 106.

  In addition, if the origin position of the product is different from the origin position stored in the driver, the motor-driven proportional valve 100 can rotate the motor 106 in the reverse direction by a predetermined rotation angle from the origin position of the driver. The valve body 104 did not descend by a predetermined amount, and a constant seal load could not be obtained. Therefore, the motor-driven proportional valve 100 has a problem that when the origin position differs for each product, the seal load is not constant for each product, and the sealing force is not stable.

The present invention has been made to solve the above problems, accurately adjust the valve opening based on the rotation angle of the motors, it is possible to improve the flow accuracy, stable sealing and purpose thereof is to provide a motor-driven proportional valve which can be obtained force.

The motor-driven proportional valve according to the present invention has the following configuration.
(1) A valve body is provided on a valve seat that allows communication between an input port and an output port so that the valve body can be contacted and separated. The motor drive force is converted into a linear motion and transmitted to the valve body. In the motor-driven proportional valve that adjusts the valve opening by controlling the rotation angle of the valve, the control means has an origin position storage means for storing the origin position at which the valve starts to actually open, Rotate the motor to detect the moment when fluid begins to flow from the input port to the output port with the flow meter attached to the output port. The rotation angle is the origin position .

Subsequently, functions and effects of the invention having the above-described configuration will be described.
When the motor rotates in the forward direction, the motor-driven proportional valve moves the valve body away from the valve seat to increase the flow rate, while when the motor rotates in the reverse direction, the valve body moves in the valve seat direction. To reduce the flow rate.

Here, when reducing the flow rate, after rotating the motor in the reverse direction so that the valve body is moved to a position where the flow rate is controlled to be lower than the target flow rate, the motor is rotated in the forward direction to target the valve body. Move to the position where the flow rate is controlled .

When reversing the direction opposite the direction of rotation of the motors from the forward direction, there is the mechanical loss due to the gap, such as between the members, corresponding to the target flow rate from the relationship between the flow rate and the rotational angle of the motor in the opening direction rotation Even if the angle is obtained and the motor is rotated in the reverse direction by the rotation angle, the valve body cannot move in the valve seat direction to the position corresponding to the target flow rate .

In the present invention, the control means stores the origin position at which the valve of the motor-driven proportional valve to be controlled is controlled by the origin position storage means, and the dimensional tolerance of the parts of the motor-driven proportional valve to be controlled Eliminates the effect of assembly tolerances on origin search. That is, the control means accurately recognizes the rotation angle from when the motor of the motor-driven proportional valve to be controlled starts to rotate until the valve actually opens. For this reason, the motor-driven proportional valve can accurately determine the origin, and can adjust the valve opening to an amount corresponding to the target flow rate based on the rotation angle of the motor. In addition, the motor-driven proportional valve, when the motor is rotated by a predetermined rotation angle from the origin position stored in the origin position storage means of the control means, the valve body is lowered by a predetermined amount, and a constant amount is obtained. A seal load is obtained. Therefore, in the motor-driven proportional valve, even if the origin position is different for each product, the sealing load is constant for each product, and the sealing force is stabilized. Therefore, the motor-driven proportional valve of the present invention can accurately adjust the valve opening based on the rotation angle of the motor, improve the flow rate accuracy, and obtain a stable sealing force.

Next, an embodiment of a motor-driven proportional valve according to the present invention will be described with reference to the drawings. 1 and 2 are sectional views of the motor-driven proportional valve 1.
The motor-driven proportional valve 1 is installed, for example, on the reformed gas pipe of the fuel cell, and is used for adjusting the flow rate of the reformed gas. The motor-driven proportional valve 1 has a needle valve body 10 in contact with or separated from a valve seat 6 disposed between the input port 3 and the output port 4 and is connected to the needle valve body 10. It is characterized by a driver (corresponding to “control means”) 25 that controls the motor 15.

  In the motor-driven proportional valve 1, an input port 3 and an output port 4 are formed in a body 2, and a valve chamber 5 is formed between the input port 3 and the output port 4. In the valve chamber 5, a valve seat 6 is formed at an opening where the output port 4 communicates. The valve chamber 5 is formed by airtightly attaching a shaft guide 7 to a bottomed hole formed in the body 2, and a valve shaft 8 is slidably held by the shaft guide 7. A holding washer 9 is attached to the lower end portion of the valve shaft 8, and the needle valve body 10 is held by the holding washer 9 so as to be slidable in the axial direction. The needle valve body 10 is disposed so that the tip end portion is inserted into the valve seat 6, and a spring 11 is contracted between the holding washer 9 and the needle valve body 10. The spring 11 prevents the needle valve body 10 from being pressed against the valve seat 6 beyond a predetermined sealing load. Therefore, if the valve shaft 8 is moved up and down to change the area of the gap formed between the needle valve body 10 and the valve seat 6, the fluid supplied to the input port 3 is slightly adjusted at the valve portion. Can be output from the output port 4.

  An adapter 12 having a hollow hole is fixed to the body 2 with a bolt 14 via a tightening plate 13, and an upper end portion of the valve shaft 8 projects from the body 2 to the adapter 12 via the tightening plate 13. The stepping motor 15 is fixed to the adapter 12, and the drive shaft 16 protrudes downward into the adapter 12 and is connected to the valve shaft 8 via the conversion mechanism 17, and the valve shaft according to the rotation of the stepping motor 15. 8 is configured to linearly move up and down. FIG. 3 is an exploded perspective view of the conversion mechanism 17.

  The conversion mechanism 17 includes a drive shaft 16, a rotation member 18, a guide member 19, and the like, and is accommodated in the adapter 12. The guide member 19 is formed by molding a plastic material into a substantially cylindrical shape by injection molding. The guide member 19 is disposed so that the tip end protrudes from the fastening plate 13 to the adapter 12, and the lower end portion is held between the shaft guide 7 and the fastening plate 13, so that movement in the rotational direction is restricted. ing. The guide member 19 has a pair of elongated holes 20 formed in the outer peripheral surface so as to be long in the axial direction. The valve shaft 8 has an upper end inserted into the guide member 19 and is penetrated and fixed so that the engagement pin 21 is inserted into the elongated hole 20 of the guide member 19. On the other hand, the rotating member 18 is formed by forming a plastic material into a bag shape by injection molding, and is mounted so as to cover the distal end portion of the guide member 19. A pair of feed screws 22 are formed in a female thread shape on the inner peripheral surface of the rotating member 18, and both end portions of the engagement pins 21 are slidably fitted to the feed screws 22, 22. The rotating member 18 is configured such that the convex portion 23 is uniquely positioned and engaged with the concave portion 24 of the drive shaft 16 and rotates integrally with the drive shaft 16. Therefore, when the stepping motor 15 rotates the rotary member 18 via the drive shaft 16, the feed pin 22 moves the engagement pin 21 along the long hole 20 of the guide member 19, and the valve shaft 8 is slid in the axial direction. Move. Therefore, if the rotation of the stepping motor 15 is controlled, the amount of movement of the needle valve body 10 in the vertical direction can be adjusted.

A driver 25 for controlling the rotation operation is attached to the stepping motor 15. FIG. 4 is a block diagram of the driver 25.
The driver 25 includes an input / output interface 26, a central processing unit (hereinafter referred to as “CPU”), a ROM 28, a RAM 29, and the like. The input interface 26 is connected to the stepping motor 15 to output a control signal or input external information. The CPU processes and calculates data. The ROM 28 stores programs and data. The ROM 28, the valve opening control program 3 0 of Reference Example to be described later, home position correction program 31 will be described later, the hysteresis storage memory 3 2 of Reference Example described later, which will be described later origin position storage memory ( "home position storage means ”). 33 and the like. The RAM 29 temporarily stores data.

Here, the valve opening degree adjustment program 30, the origin position correction program 31, the hysteresis storage memory 32, and the origin position storage memory 33 described above will be described.
The hysteresis storage memory 32 stores data relating to hysteresis, such as hysteresis characteristics, the maximum hysteresis width of the hysteresis characteristics, and a predetermined hysteresis width α.

  Here, the predetermined hysteresis width α refers to a reference value for determining the number of steps when adjusting the valve opening. The predetermined hysteresis width α is preferably equal to or greater than the maximum value of the varying hysteresis width as shown in FIG. The reason why the hysteresis width is equal to or greater than the maximum value is to surely eliminate the hysteresis at any rotational position of the stepping motor 15. In particular, it is desirable that the predetermined hysteresis width α is not less than the maximum hysteresis width and not more than twice the maximum hysteresis width. The reason why the hysteresis width is not more than twice the maximum value is to cope with dimensional tolerances and assembly tolerances of parts and the like. Furthermore, it is desirable that the predetermined hysteresis width α is not less than the maximum hysteresis width and not more than 1.1 times the maximum hysteresis width. This is because the amount of movement of the needle valve body 10 is reduced by setting the hysteresis width α as small as possible, and the flow rate adjustment time is shortened.

  In the present embodiment, the needle valve body 10 moves to the fully open position when it rises 6 mm from the fully closed position, and it is necessary to supply 1500 pulses of current to the stepping motor 15 in order to move the needle valve body 10 by 6 mm. Shall. In this case, it is assumed that the maximum hysteresis width is 40 pulses, the predetermined hysteresis width α is set to 80 pulses that is twice the maximum hysteresis width (40 pulses), and is stored in the hysteresis storage memory 32.

Next, the valve opening degree adjustment program 30 will be described.
The valve opening degree adjustment program 30 is for executing a process for always adjusting the valve opening degree on the inclination of the hysteresis characteristic in the opening direction. The valve opening degree adjustment program 30 is read from the ROM 28 by the CPU 27 and executed. 5 and 6 are diagrams conceptually showing the contents of a valve opening degree adjustment program as a reference example .

  Specifically, when increasing the flow rate, first, the hysteresis characteristic stored in the hysteresis storage memory 32 is read out and stored in the RAM 29. Then, as shown in FIG. 5, the number of steps S1 required to raise the needle valve body 10 from the stop position P1 to the position P2 where the flow rate can be adjusted to the target flow rate is determined based on the inclination of the hysteresis characteristic in the opening direction. To do. Then, a control signal for rotating in the positive direction by the determined number of steps S 1 is output from the input / output interface 26 to the stepping motor 15.

  On the other hand, when the flow rate is decreased, the hysteresis characteristic and the predetermined hysteresis width α are read from the hysteresis storage memory 32 and stored in the RAM 29. Then, as shown in FIG. 6, after the needle valve body 10 is lowered from the stop position P3 to a position P5 where the flow rate is controlled to be lower than the target flow rate, the target flow rate is controlled by putting the hysteresis characteristic in the opening direction. The number of steps for raising the needle valve body 10 to the position P7 is determined. Then, a control signal for rotating the stepping motor 15 by the determined number of steps is output from the input / output interface 26 to the stepping motor 15.

  Specifically, first, the step number S2 corresponding to the target flow rate is obtained based on the inclination of the hysteresis characteristic in the opening direction. Then, a step number S3 corresponding to a predetermined hysteresis width α is obtained. Then, the stepping motor 15 is rotated in the reverse direction by the step number S2 + S3 obtained by adding the step number S2 and the step number S3, and a control signal for lowering the needle valve body 10 is created. Further, a control signal for rotating the stepping motor 15 in the forward direction by the number of steps S3 corresponding to the predetermined hysteresis width α is created. The generated control signal is output from the input / output interface 26 to the stepping motor 15.

Next, the origin position storage memory 33 will be described.
The origin position storage memory 33 stores the origin positions (for example, G1 and G2 in FIG. 9) at which the valve of the motor driven proportional valve 1 actually opens during product assembly. The origin position storage memory 33 stores the origin position as follows. The motor-driven proportional valve 1 is connected to a pipe through which fluid flows to the input port 3 and the output port 4 after product assembly. At this time, a flow meter is attached to the outlet of the output port 4. Then, fluid is supplied to the input port 3 of the motor-driven proportional valve 1 and the stepping motor 15 is rotated in the forward direction to raise the needle valve body 10 to the fully open position. Then, the stepping motor 15 is rotated in the reverse direction to bring the needle valve body 10 into contact with the valve seat 6. Further, the stepping motor 15 is rotated in the reverse direction to apply a predetermined sealing load to the needle valve body 10. Thereby, the stepping motor 15 returns to the position where rotation starts, that is, the position where the number of steps is zero. Then, the stepping motor 15 is rotated in the forward direction to raise the needle valve body 10 little by little. Then, the moment when the fluid starts to flow from the input port 3 to the output port 4 is detected by the flow meter, and the detected position (for example, G1 and G2 in FIG. 9) is stored in the origin position storage memory 33. Accordingly, the origin position stored in the origin position storage memory 33 of the motor driven proportional valve 1 may be different for each product.

Next, the origin position correction program 31 will be described.
The origin position correction program 31 shifts the origin position of the hysteresis characteristic stored in the hysteresis storage memory 32 based on the origin position (for example, G1 and G2 in FIG. 9) stored in the origin position storage memory 33, This is for executing a process for finding the origin.

Next, the operation of the motor driven proportional valve 1 will be described.
In the motor-driven proportional valve 1, before turning on the power, the valve shaft 8 is lowered as shown in FIG. 1, and the tip of the needle valve element 10 is inserted into the valve seat 6. The needle valve body 10 is applied with a predetermined sealing load by the spring 11 and reliably seals the valve seat 6. Therefore, no fluid flows from the input port 3 to the output port 4.

  When the valve opening is changed from the fully closed state to the fully open state, as shown in FIG. 2, the stepping motor 15 is rotated in the forward direction to raise the valve shaft 8. Since the needle valve body 10 is biased in the direction of the valve seat 6 by the spring 11, even if the valve shaft 8 starts to rise, the needle valve body 10 continues to contact the valve seat 6 for a while. When the valve shaft 8 is raised by a predetermined amount, the holding washer 9 is engaged with the needle valve body 10. When the valve shaft 8 is further raised thereafter, the needle valve body 10 is moved via the holding washer 9 to the valve seat 6. It is raised from. As a result, the fluid supplied to the input port 3 starts to flow to the output port 4. Thereafter, when the stepping motor 15 is rotated in the positive direction by a predetermined number of steps corresponding to the fully opened position, the needle valve body 10 is raised according to the number of steps and moved to the fully opened position.

  On the other hand, when the valve opening is changed from the fully open state to the fully closed state, as shown in FIG. 1, the stepping motor 15 is rotated in the reverse direction to lower the valve shaft 8. The needle valve body 10 descends together with the valve shaft 8 and eventually returns to the origin position. Thereafter, the stepping motor 15 rotates in the reverse direction by a predetermined number of steps to lower the valve shaft 8 and presses the needle valve body 10 against the valve seat 6 with a predetermined sealing load. Even if the stepping motor 15 rotates too much, the spring 11 absorbs the load in the direction of the valve seat 6, so that the needle valve body 10 is not pressed too strongly against the valve seat 6.

  Next, a case where the fluid flow rate is adjusted to a minute flow rate will be described. When increasing the flow rate, as shown in FIG. 5, the stepping motor 15 is rotated in the forward direction by the number of steps S1 corresponding to the target flow rate based on the inclination of the hysteresis characteristic in the opening direction, and the needle valve body 10 is moved. The position is raised from the stop position P1 to a position P2 corresponding to the target flow rate. At this time, since the motor-driven proportional valve 1 always adjusts the flow rate by rotating the stepping motor 15 in the positive direction, the stop position P1 is on the inclination in the opening direction, and the number of steps S1 is taken into consideration for hysteresis. There is no need to decide.

  On the other hand, when decreasing the flow rate, as shown in FIG. 6, first, the number of steps S2 corresponding to the target flow rate obtained from the inclination of the hysteresis characteristic in the opening direction and the number of steps corresponding to the predetermined hysteresis width α. By rotating the stepping motor 15 in the reverse direction by the number of steps S2 + S3 obtained by adding S3, the needle valve body 10 is lowered and the flow rate is decreased.

  This is because hysteresis occurs due to frictional resistance and gaps generated at the connecting portion between the drive shaft 16 and the rotating member 18 of the stepping motor 15 and the connecting portion between the feed screw 22 and the engaging pin 21. Only by rotating the stepping motor 15 in the reverse direction by the number of steps S2 corresponding to the target flow rate obtained from the inclination in the direction, the needle valve body 10 can be lowered only to the position P4. That is, the flow rate is controlled more than the target flow rate. On the other hand, if the stepping motor 15 is rotated in the reverse direction by the number of steps obtained by adding the number of steps corresponding to the constant hysteresis width to the number of steps S2 corresponding to the target flow rate with the hysteresis width being constant, the fluid is supplied to the target flow rate. It is thought that it can be controlled.

  However, in the motor-driven proportional valve 1 of the present embodiment, since the rotating member 18 is formed by injection molding, the shape of the feed screw 22 and the convex portion 23 is not easily constant due to sink marks during cooling. Therefore, when the stepping motor 15 rotates, rattling occurs at the connecting portion between the drive shaft 16 of the stepping motor 15 and the rotating member 18 and at the connecting portion between the feed screw 22 of the rotating member 18 and the engaging pin 21 of the valve shaft 8. However, this has changed the hysteresis width. Therefore, simply by determining the number of steps in consideration of a certain hysteresis width, the fluid cannot be adjusted to the target flow rate when the certain hysteresis width and the actual hysteresis width do not match.

On the other hand, the motor-driven proportional valve 1 has a predetermined hysteresis width stored in advance in the hysteresis storage memory 32 in addition to the step number S2 corresponding to the target flow rate by a valve opening degree adjustment program as a reference example. The stepping motor 15 is rotated in the reverse direction by the number of steps S3 corresponding to α. Since the predetermined hysteresis width α is a value (80 pulses) obtained by doubling the maximum value (40 pulses) of the varying hysteresis width, the hysteresis generated at any rotational position of the stepping motor 15 can be eliminated. However, in this case, if the predetermined hysteresis width α is larger than the hysteresis width at the stop position P3, the needle valve body 10 is lowered to a position P5 that controls a flow rate lower than the target flow rate.

In order to eliminate this problem , the motor-driven proportional valve 1 rotates the stepping motor 15 in the forward direction by the number of steps S3 corresponding to the predetermined hysteresis width α by this valve opening degree adjustment program as a reference example . In this case, when the stepping motor 15 rotates in the positive direction by the number of steps S4 corresponding to the hysteresis width at the position P5, the hysteresis is eliminated and the flow rate does not change, but the needle valve element 10 is inclined in the opening direction of the hysteresis characteristic. (Refer to position P6). When the predetermined hysteresis width α and the hysteresis width at the position P5 are the same, the needle valve body 6 stops at the position P6.

  On the other hand, if the predetermined hysteresis width α is larger than the hysteresis width at the position P5, then the stepping motor 15 obtains the remaining hysteresis width, that is, the hysteresis width at the position P5 from the predetermined hysteresis width α. Rotate in the positive direction by the number of steps S5 corresponding to the hysteresis width. Thereby, the needle valve body 10 rises on the inclination of the hysteresis characteristic in the opening direction, and stops at the position P7 corresponding to the target flow rate. Thereby, the motor driven proportional valve 1 controls the fluid to the target flow rate.

  Incidentally, the motor driven proportional valve 1 may have different origin positions G1, G2 for each product, as shown by G1, G2 in FIG. On the other hand, the driver 25 stores the origin position where the valve of the motor driven proportional valve 1 to be controlled actually opens in the origin position storage memory 33, and the components of the motor driven proportional valve 1 to be controlled are stored. This eliminates the influence of dimensional tolerances and assembly tolerances on the origin search. That is, the driver 25 accurately grasps the number of steps from when the stepping motor 15 of the motor-driven proportional valve 1 to be controlled starts to rotate until the valve actually opens. For this reason, the motor-driven proportional valve 1 performs the home position accurately when the home position correction program 31 is executed, and adjusts the valve opening to an amount corresponding to the target flow rate based on the number of steps of the stepping motor 15. It is possible.

In motor-driven proportional valve 1 of this embodiment, if the reverse the stepping motor 15 from the home position a predetermined number of steps stored in the home position storage memory 33 of the driver 25, the needle valve body 10 Actually, the valve descends by a predetermined amount from the origin position at which the valve starts to open, and comes into contact with the valve seat 6 with a constant sealing load. Therefore, in the motor-driven proportional valve 1, even if the origin position varies from product to product, the seal load is constant from product to product, and a stable sealing force can be obtained.

As described above in detail, the motor-driven proportional valve 1 of the present embodiment is the origin position where the valve of the motor-driven proportional valve 1 to be controlled actually starts to open (for example, G1 and G2 in FIG. 9). Is stored in the origin position memory 33, the valve opening degree can be accurately adjusted based on the number of steps of the stepping motor 15, the flow rate accuracy can be improved, and a stable sealing force can be obtained. .

Although the embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments, and various applications are possible.
For example, in the above embodiment, the motor-driven proportional valve 1 having a needle valve structure has been described. However, the driver 25 may be applied to a motor-driven proportional valve having a poppet valve structure. In the above embodiment, the engagement pin 21 of the valve shaft 8 is engaged with the feed screw 20 of the conversion mechanism 17, but a male screw is formed at the upper end portion of the valve shaft 8 to feed the conversion mechanism 17. The screw 20 may be screwed together.

It is sectional drawing of a motor drive type proportional valve concerning embodiment of this invention, Comprising: A fully closed state is shown. Similarly, it is sectional drawing of a motor drive type proportional valve, Comprising: A valve opening state is shown. Similarly, it is an exploded perspective view of a conversion mechanism. It is a block diagram of a driver. It is the figure which showed notionally the content of the valve opening degree adjustment program which is a reference example, Comprising: The case where a valve body is moved to an opening direction is shown. It is the figure which showed notionally the content of the valve opening degree adjustment program which is a reference example, Comprising: The case where a valve body is moved to a close direction is shown. It is sectional drawing of the conventional motor drive type proportional valve. It is a figure which shows the hysteresis characteristic of a motor drive type proportional valve, Comprising: A flow rate (L / min) is shown on a vertical axis | shaft, and a step number is shown on an engagement pin. It is the figure which compared the hysteresis characteristic of two motor drive type proportional valves, Comprising: A flow rate (L / min) is shown on a vertical axis | shaft and a step number is shown on an engagement pin.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor drive type proportional valve 3 Input port 4 Output port 6 Valve seat 10 Needle valve body 15 Stepping motor 25 Driver 30 Valve opening degree adjustment program 32 Hysteresis memory memory 33 Origin position memory

Claims (1)

A valve body is provided in a valve seat that allows the input port and the output port to communicate with each other so that the valve body can be contacted and separated, and the driving force of the motor is converted into a linear motion and transmitted to the valve body. In a motor-driven proportional valve that adjusts the valve opening by controlling the angle,
The control means includes origin position storage means for storing an origin position at which the valve actually starts to open ;
After product assembly, actually performing piping, rotating the motor, and detecting the moment when fluid begins to flow from the input port toward the output port by a flow meter attached to the output port;
The motor-driven proportional valve characterized in that the origin position storage means uses the rotation angle of the motor when detected by the flow meter as the origin position .

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