JP4311981B2 - Valve control device and origin search method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve control device that controls the flow rate of a liquid such as a semiconductor product or a pharmaceutical product, and more particularly to a valve control device that searches and sets the origin of a closing position that serves as a reference for the valve opening.
[0002]
[Prior art]
A conventional valve control device includes a cylindrical cylinder, an actuator having a vane body that is swingably disposed in the cylinder, an optical rotary encoder that detects the position of the vane body in conjunction with the actuator, It consists of a control device. (See "Patent Document 1" (valve closing detection device))
[0003]
The valve closing detection device configured in this way stops the vane body by supplying compressed air to the actuator and confirming that the state of the actuator is appropriate by the display monitor display when the operator starts the initial state. Swing to the closed end position until
[0004]
When the number of bits input from the rotary encoder is fluctuating, the control device determines that the vane body is oscillating, and when the vane body does not fluctuate for a certain time, the vane body is stopped. Therefore, the number of output bits of the rotary encoder is stored in the memory as the closing position of the vane body (corresponding to the valve).
[0005]
After the initial setting, the normal valve opening / closing operation is executed. Even if the closing position of the vane body (corresponding to the valve) fluctuates for each valve operation, the number of output bits changed even if the number of output bits of the rotary encoder changes. Is updated as the closing position.
[0006]
As described above, the conventional valve control device creates the closing position data based on the stop position of the vane body before the opening / closing operation of the valve of the gas container, and detects the closing state of the valve with high accuracy. Since the closing position data can be updated for each operation, the reliability can be further improved.
[0007]
[Patent Document 1]
JP-A-10-78199 (FIGS. 1 and 2)
[0008]
[Problems to be solved by the invention]
In the conventional valve control device, when the device is introduced, the operator has to initially set the valve closing position, and there are troublesome cases, and there is a problem that the usability is inferior.
[0009]
The present invention has been made to solve such problems, and an object of the present invention is to provide a highly convenient valve control device that can periodically and automatically execute the origin search of the valve closing position. It is in.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a valve control device according to the present invention has a pulse motor that adjusts the degree of opening and closing by driving a valve that opens and closes a liquid flow path, and is associated with the rotation angle of the pulse motor in conjunction with the pulse motor. comprising a rotary encoder for detecting a pulse number, and a control device for controlling the valve opening degree based on the detected number of pulses supplied from the pulse count and the rotary encoder for driving the pulse motor, the liquid passing through the valve A valve control device for controlling a flow rate, wherein the control device supplies an arbitrary number of Ni pulses for driving the valve in the closing direction to the pulse motor, and the pulse motor detects a detection pulse corresponding to the arbitrary number of Ni pulses. a case which can not be obtained from the encoder after detecting the out-of the valve is in the closed position of the flow passage, further driving the valve in the closing direction That pulses of a predetermined number N1 is supplied to the pulse motor to further refine the valve, then the valve pulse position obtained by supplying the pulse motor to the prescribed number N2 for driving the valve in the opening direction (N2 <N1) An origin search means for searching as the origin of the closed position is provided.
[0011]
The control device of the valve control device according to the present invention supplies a pulse for driving the valve in the closing direction to the pulse motor, and after detecting a step-out of the pulse motor, further pulses a predetermined pulse for driving the valve in the closing direction. Since it has origin search means to search the origin of the valve closing position by supplying a specified pulse to the motor and then driving the valve in the opening direction to the pulse motor, it has flexibility in the valve closing position By setting the origin, the origin can be set even if the valve is worn due to a change over time, and the convenience can be improved.
[0012]
Further, the origin search means according to the present invention supplies an arbitrary number of Ni pulses for driving the valve in the closing direction to the pulse motor, and the pulse motor detects a detection pulse corresponding to the arbitrary number of Ni pulses on the rotary motor. Step-out detection means that detects when the valve cannot be obtained from the encoder as a step-out state in which the valve is in the closed position of the flow path, generation of an arbitrary number of pulses that drive the valve in the closing direction, and the valve is in the closed position of the flow path generation of a pulse of a predetermined number N1 of the further valve after detecting the out-of that to filter driven in the closing direction, and the occurrence of pulses of defined number N2 for driving the valve in the opening direction, in order to the pulse motor And a sequence means for designating supply.
[0013]
The origin search means according to the present invention comprises a step-out detection means for detecting step-out of the pulse motor and a sequence means for designating the order of step-out detection, predetermined pulse generation, and prescribed pulse generation. Thus, the origin of the valve closing position can be set.
[0014]
Furthermore, the control device according to the present invention is characterized in that it includes an activation means for activating the origin search means when the apparatus is turned on.
[0015]
Since the control apparatus according to the present invention includes the starting means for starting the origin search means when the apparatus is turned on, the origin of the valve closing position can be set regularly and automatically, and is easy to use. Appeal goodness.
[0016]
Also, the control device according to the present invention detects an abnormality in the degree of opening and closing of the valve when the number of detected pulses supplied from the rotary encoder exceeds the allowable range with respect to the number of pulses for driving the pulse motor. comprising means, characterized Rukoto operates the starting means based on the abnormality signal from the abnormality detecting means.
[0017]
The control device according to the present invention includes an abnormality detecting means for detecting an abnormality in the degree of opening and closing of the valve, and operates the starting means based on an abnormality signal from the abnormality detecting means. When this occurs, the origin of the valve closing position can be automatically set reliably, and the reliability of the origin setting of the closing position can be improved.
[0018]
Furthermore, the rotary encoder according to the present invention generates a detection pulse multiplied by an arbitrary number of Ni pulses for driving the valve in the closing direction by the pulse motor, and the pulse motor corresponds to an arbitrary number of Ni pulses. as detected pulses the case that can not be obtained from the rotary encoder valve becomes out-of in the closed position of the flow passage, characterized in that it does not generate the detection pulse.
[0019]
The rotary encoder according to the present invention generates a detection pulse that is a multiplication of the pulse that drives the pulse motor, and does not generate a detection pulse when the pulse motor steps out. Also, the closed position can be reliably detected.
[0020]
In addition, the origin search method of the valve control device according to the present invention corresponds to a pulse motor that drives a valve that opens and closes a liquid flow path to adjust the degree of opening and closing, and corresponds to the rotation angle of the pulse motor in conjunction with the pulse motor. A rotary encoder that detects the number of pulses, and a control device that controls the degree of opening and closing of the valve based on the number of pulses that drive the pulse motor and the number of detected pulses that are supplied from the rotary encoder. An origin search method for a valve control device for controlling a flow rate, in which a valve is closed and driven by an arbitrary number of Ni pulses supplied from a pulse motor, and an arbitrary number Ni supplied to a pulse motor by a rotary encoder Sources of detecting if not obtained a detection pulse corresponding to a pulse as a step-out state in which the valve is in the closed position of the flow passage And-up S2, after detecting the out-of, and step S3 to narrow the valve by driving the valve in the closing direction by supplying a pulse of a predetermined number N1 to drive the valve in the closing direction further to the pulse motor, then And a step S4 of searching the position obtained by supplying the pulse motor with a prescribed number N2 (N2 <N1) of pulses for driving the valve in the opening direction as the origin of the valve closing position .
[0021]
The origin search method of the valve control apparatus according to the present invention includes a step S1 for driving the valve to close, a step S2 for detecting and stopping the stepping out of the pulse motor, and a stop by driving the pulse motor in the closing direction with a predetermined pulse Step S3, and a step S4 for driving and stopping the pulse motor in the opening direction with a prescribed pulse, so that the origin can be set with a degree of freedom in the valve closing position, which improves convenience. Can be realized.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. The present invention periodically and automatically executes a search for the origin (reference) of the valve closing position for controlling the flow rate of liquid such as semiconductor products and pharmaceuticals with high accuracy.
[0023]
FIG. 1 is a block diagram of a main part of an embodiment of a valve control device according to the present invention. In FIG. 1, the valve control device 1 includes a control device 2, a rotary encoder 4, a stepping motor 5, a rotation / linear motion conversion mechanism 6, a valve 7, a flow passage 8, and an operation key 9.
[0024]
The control device 2 supplies a driving pulse PD for driving the valve 7 in the closing direction D to the stepping motor 5 constituting the pulse motor, and further detects the step-out of the stepping motor 5 and then further drives the valve 7 in the closing direction D. A predetermined driving pulse PD is supplied to the stepping motor 5 , and then a prescribed driving pulse PD for driving the valve 7 in the opening direction U is supplied to the stepping motor 5 to search the origin (O) of the closing position of the valve 7. Origin search means 3 is provided.
[0025]
Further, the control device 2 supplies a driving pulse PD for driving the stepping motor 5 clockwise or counterclockwise.
[0026]
Further, the control device 2 monitors the coincidence and non-coincidence with the drive pulse PD based on the detection pulse PO supplied from the rotary encoder 4, and manages whether or not the stepping motor 5 rotates accurately by the drive pulse PD. .
[0027]
The rotary encoder 4 optically detects the detection pulse PO corresponding to the rotation angle of the stepping motor 5 in conjunction with the rotational movement of the stepping motor 5 and provides the detection pulse PO to the control device 2.
[0028]
Further, the rotary encoder 4 generates a detection pulse PO that is a multiplication (for example, 2 times) of the drive pulse PD, and when the stepping motor 5 (pulse motor) steps out and stops rotating, the detection pulse PO is detected. Does not generate PO.
[0029]
The step out of the stepping motor 5 means that the stepping motor 5 does not rotate or does not rotate as specified even if the drive pulse PD is supplied from the control device 2 to the stepping motor 5. In general, when the rotary encoder 4 is attached to the shaft of the stepping motor 5 and the detection pulse PO from the rotary encoder 4 is fed back to the control device 2, the detection pulse PO corresponding to the drive pulse PD is obtained. If no, step out.
[0030]
As described above, the rotary encoder 4 according to the present invention generates the detection pulse PO that is a multiple of the pulse (drive pulse PD) for driving the pulse motor 5, and also detects the detection pulse when the pulse motor 5 steps out. Since PO is not generated, the closed position can be reliably detected even if the valve 7 starts to close from an arbitrary opening degree.
[0031]
The rotation / linear motion conversion mechanism 6 includes, for example, a rack and pinion mechanism, converts the rotational motion of the stepping motor 5 into the linear motion of the valve 7, moves the valve 7 in the opening direction U or the closing direction D, and the flow path 8. The opening KO of the inner valve 7 is adjusted to control the flow rate of a liquid such as a semiconductor product or medicine flowing in the flow path 8 in the X direction or the -X direction.
[0032]
Since the control device 2, the stepping motor 5 and the rotary encoder 4 form a feedback loop, the opening degree KO of the valve 7 corresponding to the drive pulse PD can be accurately determined by monitoring the drive pulse PD and the detection pulse PO. The flow rate of the liquid flowing through the flow passage 8 can be accurately controlled.
[0033]
The personal computer PC and the operation keys 9 output setting data DS and key information JK, respectively, for setting various data in the control device 2. The PLC (program logic controller) controls the flow of the valve control device 1 and sets various data, operation order, timing, and the like in the control device 2.
[0034]
As described above, the control device 2 of the valve control device 1 according to the present invention supplies the pulse for driving the valve 7 in the closing direction to the pulse motor (stepping motor 5), and detects the step-out of the pulse motor 5, Further, a predetermined pulse for driving the valve 7 in the closing direction is supplied to the pulse motor 5, and then a specified pulse for driving the valve 7 in the opening direction is supplied to the pulse motor 5 to search for the origin of the closing position of the valve 7. Since the origin search means 3 is provided, the origin can be set even if the valve is worn due to changes over time by setting the origin with a degree of freedom in the closed position of the valve 7. Can be improved.
[0035]
FIG. 2 is a block diagram showing the main part of one embodiment of the control apparatus according to the present invention. In FIG. 2, the control device 2 basically includes a microprocessor, and includes an origin search means 3, a control means 10, a storage means 11, a pulse generation means 12, an activation means 13, and an abnormality detection means 14. Each component of the control device 2 is connected to each other via the data bus BU.
[0036]
The control means 10 controls all the operations of the origin search means 3, the storage means 11, the pulse generation means 12, the activation means 13 and the abnormality detection means 14, and the abnormal state of the apparatus is abnormal at the time of power-on reset when the power is turned on. When the detection means 14 detects or when a signal is received from a PLC (program logic controller) that controls the flow of the entire apparatus, the starting means 13 is operated to drive the origin search means 3.
[0037]
When the control means 10 recognizes the power-on reset signal and a start command is supplied when the apparatus is turned on, the start means 13 supplies the start signal to the origin search means 3 and the origin search operation of the origin search means 3 Start up.
[0038]
The activation means 13 supplies the activation signal to the origin search means 3 when the abnormality detection means 14 detects the abnormality of the opening / closing degree of the valve 7 and the control means 10 recognizes the abnormality signal and the activation command is supplied. Then, the origin search operation of the origin search means 3 is started.
[0039]
The abnormality detection means 14 compares the drive pulse PD output from the pulse generation means 12 with the detection pulse PO received by the origin search means 3, and if the detection pulse PO exceeds the allowable range of the drive pulse PD, an abnormality is detected. Judge and output an abnormal signal.
[0040]
The storage unit 11 includes a fixed memory such as a ROM and a rewritable memory such as a RAM, and stores programming and various data set in advance from the personal computer PC and the operation keys 9.
[0041]
In addition, the storage means 11 stores the numerical values Ni, N1 and N2 of an arbitrary number of Ni pulses, a predetermined number N1 pulses and a prescribed number N2 pulses output from the pulse generation means 12 when searching for the origin of the closed position of the valve 7. And in accordance with a command from the sequence means (18) of the origin search means 3, numerical values Ni, N1 and N2 are sequentially supplied to the pulse generation means 12, and a drive pulse PD for origin search is supplied from the pulse generation means 12. generate.
[0042]
As described above, since the control device 2 according to the present invention includes the starting means 13 for starting the origin search means 3 when the apparatus 1 is turned on, the origin of the closing position of the valve 7 is regularly and automatically. Can be set, and the ease of use can be appealed.
[0043]
Further, the control device 2 according to the present invention includes the abnormality detecting means 14 for detecting an abnormality in the degree of opening and closing of the valve 7 and operates the starting means 13 based on the abnormality signal from the abnormality detecting means 14. When an abnormality occurs in the degree of opening and closing of the valve 7, the origin of the closing position of the valve 7 can be automatically set reliably, and the reliability of the origin setting of the closing position can be improved.
[0044]
FIG. 3 is a block diagram showing the principal part of one embodiment of the origin search means according to the present invention. In FIG. 3, the origin search means 3 includes a comparison means 15, a determination means 16, a step-out detection means 17, a sequence means 18, and a timer means 19, and the constituent elements are connected by a data bus BU, and the activation shown in FIG. When an activation signal is supplied from the means 13 when the apparatus is turned on or when an abnormality is detected, an origin search operation for the closing position of the valve 7 is executed. The operation of each constituent element is controlled by the control means 10 shown in FIG.
[0045]
The comparing means 15 compares an arbitrary number Ni pulses (driving pulse PD) outputted from the pulse generating means 12 with the detection pulse PO returning from the rotary encoder 4.
[0046]
The determination means 16 determines the case of drive pulse PD−detection pulse PO> ΔP (for example, 3) from the arbitrary number of Ni pulses (drive pulse PD) and the detection pulse PO compared by the comparison means 15, and determines the determination signal. Provided to the step-out detection means 17.
[0047]
When the determination signal is supplied from the determination unit 16, the step-out detection unit 17 detects that step-out has occurred in the stepping motor 5, and provides the detection signal to the sequence unit 18.
[0048]
The sequence means 18 has an order function. When an activation signal is supplied from the activation means 13 shown in FIG. 2, the sequence means 18 generates an arbitrary number of Ni pulses (drive pulse PD) for searching the origin of the closed position of the valve 7. To the pulse generation means 12.
[0049]
Further, the sequence means 18 instructs the pulse generation means 12 to generate a predetermined number N1 of pulses (drive pulse PD) when a step-out detection signal is provided from the step-out detection means 17.
[0050]
Further, the sequence means 18 instructs the pulse generation means 12 to generate a prescribed number N2 of pulses (drive pulse PD) after instructing the generation of a predetermined number N1 of pulses (drive pulse PD).
[0051]
The timer means 19 sets the time interval of the instruction order of the sequence means 18 following step-out detection → predetermined number N1 pulse generation → predetermined number N2 pulse generation.
[0052]
As described above, the origin search means 3 according to the present invention includes the step-out detection means 17 for detecting the step-out of the pulse motor (stepping motor 5), the step-out detection, the predetermined pulse generation, and the prescribed pulse generation order. Since the sequence means 18 for designating is provided, the origin of the valve closing position can be automatically set.
[0053]
Next, the origin search operation for the closing position of the valve 7 will be described. FIG. 4 is an image diagram of an embodiment of the valve position of the valve control device according to the present invention. (A) The valve is fully open, (b) the valve arbitrary opening KO, (c) the positional relationship of the valve origin O.
[0054]
The valve control device 1 of the present invention handles the flow rate of liquids such as semiconductor products and pharmaceuticals, and Teflon (registered trademark) with little chemical influence is used for the valve 7 and the pipe (flow passage 8). Since Teflon (registered trademark) is easily affected by mechanical wear, the valve 7 is pressed against the bottom surface of the flow passage 8 to be the origin O of the closed position, and the opening KO of the valve 7 is adjusted based on the origin O. Accordingly, the flow rate of the liquid such as semiconductor products and pharmaceuticals is controlled, but the origin O also changes due to the influence of change over time.
[0055]
In order to set the origin O of the closed position of the valve 7 periodically and automatically, the origin search of the valve 7 is executed. FIG. 5 is a diagram for explaining the operation of the embodiment of the valve origin search according to the present invention. The valve origin search is executed when an abnormality occurs in the opening / closing degree of the valve 7 when the valve control device 1 is turned on, or when a command is input from the personal computer PC or the operation key 9 as necessary.
[0056]
In FIG. 5, the origin search starts when the origin search is started at X0, the valve 7 is closed with an arbitrary number of Ni pulses (drive pulse PD) in the closing direction of the valve 7, and the stepping motor 5 is stepped out at X1. To stop the pulse. When the step-out occurs, the valve 7 is in the closed position of the flow passage 8.
[0057]
Subsequently, from X2 to X3, a predetermined number N1 of pulses (driving pulse PD) are further generated in the closing direction of the valve 7, and the valve 7 is narrowed down.
[0058]
Finally, from X4 to X5, a prescribed number N2 (N2 <N1) of pulses (driving pulse PD) is generated in the opening direction of the valve 7 and set as the origin O of the closing position.
[0059]
By searching for the origin of the closing position of the valve 7, step-out detection → driving with a predetermined number N1 pulses (driving pulse PD) in the closing direction → following driving with a prescribed number N2 pulses (driving pulse PD) in the opening direction Even if the valve 7 and the flow passage 8 are worn due to changes over time, the origin of the valve 7 can be set periodically and automatically.
[0060]
The opening / closing operation of the valve 7 after setting the origin will be described. FIG. 6 is a diagram for explaining the operation of the embodiment for opening and closing the valve according to the present invention. In FIG. 6, once the origin search of the valve 7 is executed, the valve 7 is driven in the opening direction by a pulse NP (drive pulse PD), and the valve opening KO at that time is set.
[0061]
In order to close the valve 7 to the origin, the valve 7 may be driven by a pulse NP (drive pulse PD) in the closing direction.
[0062]
Next, the origin search method of the valve control device will be described. FIG. 7 is a basic operation flowchart of the embodiment of the origin search method of the valve control device according to the present invention. The operation flow will be described with reference to FIG.
[0063]
In FIG. 7, in step S1, the valve is driven to close.
[0064]
In step S2, the step-out of the pulse motor is detected and stopped.
[0065]
In step S3, the pulse motor is driven in the closing direction with a predetermined pulse and stopped.
[0066]
In step S4, the pulse motor is driven in the opening direction with the prescribed pulse and stopped. Steps S1 to S4 are executed by the sequence means 18 of the origin search means 3 in order.
[0067]
Thus, the origin search method of the valve control device according to the present invention includes the step S1 for driving the valve to close, the step S2 for detecting and stopping the stepping out of the pulse motor, and the pulse motor in the closing direction with a predetermined pulse. Since step S3 for driving and stopping and step S4 for driving and stopping the pulse motor in the opening direction with a prescribed pulse are provided, the origin can be set with a degree of freedom in the valve closing position. The improvement of property can be realized.
[0068]
【The invention's effect】
As described above, the control device of the valve control device according to the present invention supplies a pulse for driving the valve in the closing direction to the pulse motor, and further detects the step-out of the pulse motor, and further drives the valve in the closing direction. It is equipped with origin search means to search the origin of the valve closing position by supplying a predetermined pulse to the pulse motor and then supplying a prescribed pulse for driving the valve in the opening direction to the pulse motor. By setting the origin with a degree of freedom in the position, the origin can be set even if the valve is worn due to changes over time, and convenience can be improved.
[0069]
The origin search means according to the present invention includes a step-out detection means for detecting step-out of the pulse motor, and a sequence means for designating the order of step-out detection, predetermined pulse generation, and prescribed pulse generation. The origin of the valve closing position can be automatically set.
[0070]
Furthermore, since the control apparatus according to the present invention includes the starting means for starting the origin search means when the apparatus is turned on, the origin of the valve closing position can be set regularly and automatically. You can appeal the ease of use.
[0071]
Further, the control device according to the present invention includes an abnormality detecting means for detecting an abnormality in the degree of opening and closing of the valve, and operates the starting means based on an abnormality signal from the abnormality detecting means. When an abnormality occurs, the origin of the valve closing position can be automatically set reliably, and the reliability of the origin setting of the closing position can be improved.
[0072]
Furthermore, the rotary encoder according to the present invention generates a detection pulse that is a multiplication of the pulse that drives the pulse motor, and does not generate a detection pulse when the pulse motor steps out. Even when closing starts, the closing position can be reliably detected.
[0073]
In addition, the origin search method of the valve control device according to the present invention includes step S1 for driving the valve to close, step S2 for detecting and stopping the stepping out of the pulse motor, and driving the pulse motor in the closing direction with a predetermined pulse. Step S3 for stopping and a step S4 for stopping by driving the pulse motor in the opening direction with a prescribed pulse, so that the origin can be set with a degree of freedom in the valve closing position. Improvements can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram of a main part of an embodiment of a valve control apparatus according to the present invention. FIG. 2 is a block diagram of a main part of an embodiment of a control apparatus according to the present invention. Fig. 4 is a block diagram of the main part of an embodiment of the search means. Fig. 4 is an image of an embodiment of the valve position of the valve control device according to the invention. FIG. 6 is a diagram for explaining the operation of an embodiment of valve opening / closing according to the present invention. FIG. 7 is a basic operation flow diagram of an embodiment of the origin search method of the valve control device according to the present invention.
DESCRIPTION OF SYMBOLS 1 Valve control apparatus 2 Control apparatus 3 Origin search means 4 Rotary encoder 5 Stepping motor 6 Rotation / linear motion conversion mechanism 7 Valve 8 Flow path 9 Operation key 10 Control means 11 Storage means 12 Pulse generation means 13 Starting means 14 Abnormality detection means 15 Comparison means 16 Determination means 17 Step-out detection means 18 Sequence means 19 Timer means PC Personal computer PD Drive pulse PO Detection pulse KO Valve opening

Claims (6)

A pulse motor for adjusting a degree of opening and closing by driving a valve for opening and closing a liquid flow passage; a rotary encoder for detecting the number of pulses corresponding to the rotation angle of the pulse motor in conjunction with the pulse motor; and the pulse motor A valve control device for controlling the flow rate of the liquid passing through the valve, and a control device for controlling the valve opening / closing degree based on the number of pulses for driving the valve and the number of detection pulses supplied from the rotary encoder. And
The control device supplies an arbitrary number of Ni pulses for driving the valve in the closing direction to the pulse motor, and the pulse motor obtains the detection pulse corresponding to the arbitrary number of Ni pulses from the rotary encoder. If the valve is not detected as a step-out state in which the valve is in the closed position of the flow path, a further predetermined number N1 of pulses for driving the valve in the closing direction is supplied to the pulse motor to further narrow the valve. Subsequently, there is provided an origin search means for searching a position obtained by supplying a pulse of a prescribed number N2 (N2 <N1) for driving the valve in the opening direction to the pulse motor as an origin of the valve closing position. A valve control device characterized by that. The origin search means supplies the pulse motor with the arbitrary number of Ni pulses for driving the valve in the closing direction, and the pulse motor detects the detection pulse corresponding to the arbitrary number of Ni pulses. and the synchronization failure detector for detecting a case that can not be obtained from the rotary encoder as a step-out state in which the valve is in the closed position of the flow passage, the occurrence of any number of pulses for driving the valve in a closing direction, wherein After detecting a step-out state in which the valve is in the closed position of the flow passage, the valve is further driven in the closing direction to generate a predetermined number N1 of pulses , and the specified number N2 of driving the valve in the opening direction. 2. A valve control device according to claim 1, further comprising a sequence means for designating supply to the pulse motor in the order of generation of pulses.   2. The valve control device according to claim 1, wherein the control device includes an activation means for activating the origin search means when the apparatus is turned on.   The control device includes an abnormality detection means for detecting an abnormality in the degree of opening and closing of the valve when the number of detected pulses supplied from the rotary encoder exceeds an allowable range with respect to the number of pulses for driving the pulse motor. 4. The valve control apparatus according to claim 3, further comprising: an actuating unit that operates based on an abnormality signal from the abnormality detecting unit. The rotary encoder generates the detection pulse multiplied by the pulse of the arbitrary number Ni that the pulse motor drives the valve in the closing direction, and the pulse motor corresponds to the pulse of the arbitrary number Ni. 2. The detection pulse is not generated when the detected pulse is not obtained from the rotary encoder, assuming that the valve is in a step-out state in the closed position of the flow passage. Valve control device. A pulse motor for adjusting a degree of opening and closing by driving a valve for opening and closing a liquid flow passage; a rotary encoder for detecting the number of pulses corresponding to the rotation angle of the pulse motor in conjunction with the pulse motor; and the pulse motor And a control device for controlling the degree of opening and closing of the valve based on the number of pulses for driving the valve and the number of detected pulses supplied from the rotary encoder, and the origin of the valve control device for controlling the flow rate of the liquid passing through the valve A search method,
Step S1 for closing the valve with an arbitrary number of Ni pulses supplied from the pulse motor;
Step S2 of detecting when the valve is unable to obtain a detection pulse corresponding to the arbitrary number of Ni pulses supplied to the pulse motor by the rotary encoder as a step-out state in which the valve is in the closed position of the flow path; ,
After detecting the step-out state, further supplying a predetermined number N1 of pulses for driving the valve in the closing direction to the pulse motor to drive the valve in the closing direction to narrow down the valve; S3;
Subsequently, a step S4 of searching a position obtained by supplying a pulse of a specified number N2 (N2 <N1) for driving the valve in the opening direction to the pulse motor as an origin of the closing position of the valve;
An origin search method for a valve control device comprising:

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