JP3634459B2 - Solenoid valve drive control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive control how suitable solenoid valve by applying the flow rate and pressure of air supplied to the pneumatic regulator to control using the solenoid valve.
[0002]
[Prior art]
For example, Japanese Patent Publication No. 7-50418 discloses a conventional technique of a pneumatic regulator for supplying a constant pressure to a pneumatic device.
[0003]
This air pressure regulator detects the discharge pressure when adjusting the discharge pressure discharged from the main valve, compares the detected discharge pressure with the set pressure, and compares the detected pressure with the solenoid valve to the diaphragm chamber according to the comparison result. Adjust the pulse width of the supplied pneumatic pulse. Then, by adjusting the pilot pressure according to the pulse width of the air pressure pulse supplied from the solenoid valve, the air supply valve body connected to the diaphragm is opened and closed, and the discharge pressure discharged from the main valve is adjusted to the set pressure. Device.
[0004]
[Problems to be solved by the invention]
By the way, as is well known, the electromagnetic valve is a device that opens and closes a valve body directly connected to the movable iron core when the movable iron core in the electromagnetic coil is attracted or separated by an exciting current.
[0005]
Therefore, in the conventional pneumatic regulator described above, when adjusting the pulse width of the pneumatic pulse, the pulse width of the electric signal supplied to the electromagnetic coil of the electromagnetic valve is changed.
[0006]
However, when the pulse width of the electrical signal is narrow, the present inventors may not generate a magnetic force that can move the movable iron core due to the generated excitation current. It has been found that the discharged valve body may not operate and the discharge pressure may not change.
[0007]
In addition, the time from the rise of the electric signal pulse until the movable core actually starts moving is due to changes in discharge pressure (port pressure), sliding resistance of the valve body, etc. It was also found that there was a problem of changing each time.
[0008]
The present invention has been made in consideration of such problems, the drive control how the solenoid valve to be able to drive an electrical signal having an optimum pulse width solenoid valves for set pressure and a set flow rate The purpose is to provide.
[0009]
[Means for Solving the Problems]
In the method of the present invention, an electric signal (S12) that increases due to a first-order lag system is supplied to an electromagnetic coil (51 ) that constitutes an electromagnetic valve (31), and an excitation current (S13) that actually flows through the electromagnetic coil (51 ). When the exciting current (S13) cannot follow the electrical signal (S12) , the movable iron core (63) attracted by the electromagnetic coil (51) moves, and the movable iron core (63) is moved to the movable iron core (63). The valve body (53) directly connected is identified as the time of opening.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 shows a configuration example of a pneumatic regulator 10 to which an embodiment of the present invention is applied.
[0017]
The air pressure regulator 10 has a main valve 11 for controlling the pressure of a pneumatic device (not shown). The casing 12 of the main valve 11 is provided with a supply port 13 connected to a pneumatic source (not shown) and a discharge port 14 connected to a pneumatic device (not shown).
[0018]
An air supply valve body 17 that opens and closes an air supply port 16 formed in the casing 12 is disposed in a passage 15 that connects the supply port 13 and the discharge port 14. The air supply port 16 is constantly biased by the compressive force.
[0019]
An exhaust port 21 is formed in the casing 12, and an exhaust valve body 23 that opens and closes the exhaust port 22 is slidably fitted to an exhaust port 22 that communicates between the exhaust port 21 and the discharge port 14. Yes.
[0020]
One end side of the exhaust valve body 23 is engaged with the air supply valve body 17, and the exhaust valve body 23 and the air supply valve body 17 are configured to be integrally interlocked. The other end side of the exhaust valve body 23 is integrally connected to the diaphragm 25.
[0021]
A two-port solenoid valve 31 for supplying a pneumatic pulse for controlling a pilot pressure applied to the diaphragm 25 and a two-port solenoid valve 32 for exhaust are connected to an outlet / inlet 27 of the diaphragm chamber 26 partitioned by the diaphragm 25. .
[0022]
Connected to the discharge port 14 is a pressure sensor 36 that detects the discharge pressure through a passage 35 formed in the casing 12, converts the pressure into an electric signal, and outputs the electric signal.
[0023]
The analog electrical signal of the discharge pressure detected by the pressure sensor 36 is converted into a digital electrical signal through an A / D converter 37 and supplied to the microcomputer 40. That is, discharge pressure information is supplied to the microcomputer 40.
[0024]
As is well known, the microcomputer 40 includes a microprocessor (MPU) corresponding to a central processing unit (CPU), an A / D conversion circuit, a D / A conversion circuit, and the like as an input / output device connected to the microprocessor. Read-only memory (ROM) to which I / O ports, control programs, system programs, etc. are written, random access memory (RAM, write / read memory) for temporarily storing processing data, timer circuit and interrupt processing circuit Etc. are provided as LSI devices integrated on a single chip.
[0025]
The microcomputer 40 basically compares the discharge pressure supplied from the A / D converter 37 with a preset pressure set in advance by an input device or the like (not shown) so that the discharge pressure becomes the preset pressure. It is something to control.
[0026]
In this case, the microcomputer 40 outputs square-wave pulse electric signals S1 and S11, and constitutes two-port solenoid valves (hereinafter also simply referred to as solenoid valves) 31 and 32 through coil drive / iron core movement detection circuits 41 and 42. In response to the detection signals S4 and S14 from the coil drive / iron core movement detection circuits 41 and 42 for detecting the change in the excitation current, the square-wave pulse electric signal S1 is supplied to the electromagnetic coils 51 and 52. , S11 is determined.
[0027]
FIG. 2 shows a general cross-sectional configuration example of the electromagnetic valve 31 (32). As can be seen from FIG. 2, the electromagnetic valve 31 (32) has an input port 61 and an output port 62, and a valve body 53 in which a passage between these input / output ports 61, 62 is directly connected to the movable iron core 63 (64). It is opened and closed by moving in the direction of the arrow (54). An electromagnetic coil 51 (52) is disposed around the movable iron core 63 (64), and an excitation current is supplied to the electromagnetic coil 51 (52), whereby the movable iron core 63 (64) is attracted and valved. The body 53 (54) is configured to open.
[0028]
When no excitation current is supplied to the electromagnetic coil 51 (52), the valve element is caused by the compression force of the spring 65 (66) disposed between the one end of the movable iron core 63 (64) and the casing 12. 53 (54) is always biased in the closing direction.
[0029]
FIG. 3 shows a principle configuration example of the coil drive / iron core movement detection circuit 41 (42). In FIG. 3, a square wave pulse electric signal S1 supplied from the microcomputer 40 is supplied to the base terminal of the transistor 73 for driving the electromagnetic coil 51 (52) through the input terminal 71 and the resistor 72 for limiting the base current. . A voltage signal S2 proportional to the exciting current i0 flowing in the electromagnetic coil 51 (52) appears in the resistor 74 connected between the emitter terminal of the transistor 73 and the ground.
[0030]
This voltage signal S2 is converted to a differentiated voltage signal S3 through a differentiating circuit 75. The differential voltage signal S3 and the reference voltage E1 are compared by the comparator 76, and an iron core movement detection signal S4 which is a binary signal of the comparison result appears at the output terminal 77. The iron core movement detection signal S4 is supplied to the microcomputer 40.
[0031]
Next, the operation of the main part of the pneumatic regulator 10 according to the above-described embodiment will be described with reference to the waveform diagram shown in FIG.
[0032]
First, it is assumed that a square-wave pulse electric signal S1, which is a voltage signal that rises from a zero value to a predetermined voltage value at time t0 in FIG. At this time t0, the pulse width Pwo is undetermined.
[0033]
When the inverted signal of the square wave pulse electric signal S1 is supplied to the electromagnetic coil 51 through the collector terminal of the transistor 73, an exciting current i0 that rises in a first-order delay system flows in the electromagnetic coil 51. A current proportional to the change flows through the resistor 74. Therefore, a voltage signal proportional to the exciting current i0 (hereinafter also referred to as an exciting current signal if necessary) S2 (see FIG. 4b) is generated in the resistor 74.
[0034]
When the excitation current signal S2 increases in a first order lag system, the output electrical signal S3 of the differentiation circuit 75 is a substantially positive constant value signal as shown in FIG. 4c.
[0035]
At this time, since the reference voltage (predetermined value close to zero value) E1 slightly higher than zero V (volt) is applied to the negative input terminal of the comparator 76, the output signal S4 of the comparator 76 (see FIG. 4d). ) Is held high. The reference voltage E1 is set to a high voltage value that does not invert the comparator 76 due to noise.
[0036]
When the exciting current i0 is supplied from the time point t0, the electromagnetic coil 51 is gradually excited and approaches saturation. As a result, as shown at the time point t1 in FIG. 4b, the exciting current signal S2 starts to decrease rapidly. . At this time t1, the movable iron core 63 is attracted to the electromagnetic coil 51 side, and the valve body 53 formed integrally with the movable iron core 63 starts moving in the arrow U direction (see FIG. 2). It can be seen that the inductance is rising.
[0037]
At the time t2, the movable iron core 63 is completely attracted to the electromagnetic coil 51, and when the movable iron core 63 reaches a point where it does not move any further upward, the valve element 53 of the electromagnetic valve 31 is completely opened. At this time point t2, the increase in inductance of the electromagnetic coil 51 stops, the electromagnetic current signal S2 increases again, and the electromagnetic coil 51 gradually reaches saturation from the time point t2.
[0038]
The output signal S3 of the differentiating circuit 75 immediately decreases from a positive value to a negative value immediately before the time point t1, and the time point t2 becomes an inflection point and rises from the negative value to a positive value all at once. After the time t2, the differential signal S3 suddenly goes to a zero value.
[0039]
Therefore, the output signal S4 of the comparator 76 changes from the high level to the low level zero value at the time t1 when the differential signal S3 becomes the reference voltage E1, and the differential signal S3 is instantaneously going to a positive value again. At a time point t2 where the reference voltage E1 is exceeded, the zero value changes to a high level.
[0040]
The microcomputer 40 can detect that the electromagnetic valve 31 has been opened between time t1 and time t2, that is, that the movable iron core 63 has moved. Therefore, the microcomputer 40 identifies that the input / output ports 61 and 62 of the solenoid valve 31 communicated between the detection times t1 and t2, and the predetermined pulse width Po with reference to the time t1 (or time t2). A square-wave pulse electric signal S1 (see FIG. 4a) is supplied to the electromagnetic coil 51 through the coil drive / iron core movement detection circuit 41. That is, in the pneumatic regulator 10, the microcomputer 40 determines that the time between the time point t0 and the time point t1 (or the time point t0 to the time point t2) is a so-called dead time, and sets the electromagnetic valve 31 to, for example, a certain time t1 to t1. When it is desired to open only for t3 (or a fixed time t2 to t3), a pulse width corresponding to the dead time is simply set to the pulse width Po (see FIG. 4a) corresponding to the fixed time t1 to t3 (or the fixed time t2 to t3). It is also referred to as dead time.) It is determined that the total pulse width Pwo of Pu (see FIG. 4b) is the optimum pulse width, and the corresponding square-wave pulse electric signal S1 is output.
[0041]
As described above, by using the circuit of FIG. 3, the microcomputer 40 detects the dead time Pu and then has a square having a pulse width Po corresponding to a predetermined design time for opening the solenoid valve 31. A wave pulse electrical signal S1 can be output. The dead time Pu changes depending on the discharge pressure from the electromagnetic valve 31 and the sliding resistance of the valve body 53, and there is also a secular change. According to this embodiment, the dead time Pu is detected after the dead time Pu is detected. The entire pulse width Pwo (Pu + Po) of the wave pulse electric signal S1 can be determined, and the electromagnetic valve 31 can be driven by an electric signal having an optimal (accurate) pulse width Pwo for the set pressure and set flow rate. The effect is achieved.
[0042]
FIG. 5 shows a configuration example of a coil drive / iron core movement detection circuit 41A according to another embodiment of the present invention. As will be described in detail below, this embodiment is characterized in that the electromagnetic coil 51 is driven by supplying an electric signal that is increased by a first-order lag system. The coil drive / core movement detection circuit 41A is a circuit corresponding to the coil drive / core movement detection circuit 41 in the example of FIG. 1, but the circuit corresponding to the coil drive / core movement detection circuit 42 has the same configuration. Therefore, hereinafter, only the coil drive / core movement detection circuit 41A will be described in order to avoid complication. Also, in FIG. 5, the same reference numerals are assigned to the components corresponding to those shown in FIGS. 1 to 4, and detailed description thereof is omitted.
[0043]
FIG. 6 is a waveform diagram used for explaining the operation of the coil drive / iron core movement detection circuit 41A of FIG. 5 example.
[0044]
First, at time t10, the negative polarity square wave pulse electric signal S11 shown in FIG. This square wave pulse electric signal S11 is supplied to the base terminal of the common emitter transistor 80 through the resistor 72, and the transistor 80 is turned off.
[0045]
Therefore, a voltage signal S12 that increases due to the first-order lag system shown in FIG. 6B appears at the collector terminal of the transistor 80 and is supplied to the positive input terminal of the differential amplifier 84. As is well known, the waveform of the voltage signal S12 is a waveform according to the following equation (1).
[0046]
S12 = E2 × [1-exp {(− 1 / CR) t}] (1)
Here, E2 is a divided value of the power supply voltage E by the resistor 81 (resistance value is R1) and the resistor 82 (resistance value is R2), that is, E2 = E × R2 / (R1 + R2). ). C is the capacitance value of the capacitor 83. R is the parallel resistance value {R = R1 × R2 / (R1 + R2)} of the resistor 81 and the resistor 82. t is time.
[0047]
Between time t10 and time t11, a current signal proportional to the voltage signal S12 flows through the electromagnetic coil 51. That is, when the voltage signal S12 rises, the base terminal of the transistor 85 that is the output terminal of the differential amplifier 84 rises, and a current flows from the collector terminal of the transistor 85 toward the emitter terminal. This current is supplied as the base current of the transistor 86, and the voltage signal S13 that is the terminal voltage of the resistor 87 (this voltage signal S13 is proportional to the exciting current i0 that is the current signal that flows through the electromagnetic coil 51. Current signal S <b> 13) rises and is supplied to the negative input terminal of the differential amplifier 84.
[0048]
During the period from time t10 to time t11 when the feedback loop including the differential amplifier 84, the transistors 85 and 86, and the resistor 87 is operating normally, the voltage signal S12 and the voltage signal (current signal) S13 have the same waveform. is there. The voltage signal S14 appearing at the resistor 88 connected between the emitter terminal of the transistor 85 and the ground also has a waveform proportional to the voltage signal S12. The level of the output signal S15 of the comparator 76 in which the voltage signal S14 is supplied to the positive input terminal and the positive reference voltage signal Vref (see FIG. 6c) is supplied to the negative input terminal is the one-dot chain line in FIG. 6c. As shown, it is at a low level (zero level) in the period from time t10 to time t11.
[0049]
Between time t11 and time t12, the movable iron core 63 constituting the electromagnetic valve 31 is attracted by the exciting current i0 of the electromagnetic coil 51, and the inductance value of the electromagnetic coil 51 increases rapidly. During this time, the current signal S13 flowing through the electromagnetic coil 51 decreases, and this current signal S13 increases toward the voltage signal S12 again from the time t12 when the movable iron core 63 is completely attracted.
[0050]
At time t <b> 11, the voltage signal S <b> 13 that appears at the negative input terminal of the differential amplifier 84 tends to drop, so that the voltage that appears at the base terminal of the transistor 85 increases and a current flows rapidly through the transistor 85. As a result, the voltage signal S14 appearing at the terminal of the resistor 88 increases instantaneously as shown in FIG. 6c. When the voltage signal S14 increases, the reference voltage signal Vref set so as to exceed in advance is exceeded, so that the output signal S15 of the comparator 76 shifts from the low level to the high level as shown in FIG. 6c.
[0051]
When the voltage signal S11 (see FIG. 6a) shifts from the low level to the high level at time t13, the transistor 80 changes from the off state to the on state, the positive input terminal of the differential amplifier 84 instantaneously changes to the low level, and the electromagnetic coil No current flows through 51, and the voltage signal S13 also instantaneously goes low. In this case, the resistance value of the resistor 87 is selected to be a small value in advance so that the time constant of the discharge current related to the electromagnetic coil 51 becomes smaller than the time constant CR of the above-described equation (1).
[0052]
As described above, by adopting the circuit configuration example shown in FIG. 5 and the driving method shown in FIG. 6, the microcomputer 40 has the same air pressure regulator 10 as described with reference to FIG. 3. When it is determined that the time between the time point t10 and the time point t11 (or the time point t10 to the time point t12) is a so-called dead time, and the electromagnetic valve 31 is to be opened for a certain time t11 to t13 (or a certain time t12 to t13), for example, The pulse width Pwo that is the sum of the pulse width Po (referred to as dead time) Pu corresponding to the dead time and the pulse width Po (see FIG. 6a) corresponding to the given times t11 to t13 (or the fixed times t12 to t13) is optimal. What is necessary is just to determine that it is a pulse width and to output the corresponding square wave pulse electrical signal S11.
[0053]
As described above, according to the embodiment of FIG. 3 and FIG. 5 described above, when the electromagnetic valve 31 is driven from the microcomputer 40, the output signals S4 and S15 of the coil drive / core movement detection circuit 41 An effect is achieved that the dead time Pu of the electromagnetic valve 31 is detected, and the set pressure and the set flow rate of the discharge port 14 of the pneumatic regulator 10 can be accurately controlled by the pulse width Pwo after the dead time Pu.
[0054]
Note that the present invention is not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.
[0055]
【The invention's effect】
As described above, according to the present invention, the movement of the movable iron core is detected by detecting a change in the excitation current flowing in the electromagnetic coil of the solenoid valve, and the electromagnetic valve dead time is detected to drive the solenoid valve. The pulse width of the square wave pulse electric signal to be determined is determined. The detection of dead time, electric solenoid valve is driven by an electrical signal which increases by the primary delay system and method for detecting the time until the exciting current becomes unable to follow the input electrical signal as dead time Can be adopted. For this reason, when the solenoid valve is driven with a so-called pulse width, it is possible to drive with an optimum pulse width for changing the pressure, and the effect that the pressure and the flow rate can be reliably changed is achieved. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a configuration example of a solenoid valve.
3 is a circuit diagram showing a configuration example of a coil drive / iron core movement detection circuit in the example of FIG. 1; FIG.
4a to 4d are waveform diagrams used for explaining the operation of the example in FIG. 3;
FIG. 5 is a circuit diagram showing another configuration example of a coil drive / iron core movement detection circuit;
6a to 6c are waveform diagrams used for explaining the operation of the example of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Pneumatic regulator 11 ... Main valve 13 ... Supply port 14 ... Discharge port 17 ... Supply valve body 25 ... Diaphragm 31, 32 ... Electromagnetic valve 40 ... Microcomputer 41, 41A, 42 ... Coil drive and iron core movement detection circuit 51, 52 ... Electromagnetic coil 53, 54 ... Valve body 63, 64 ... Movable iron core

Claims (1)

An electric signal (S12) that increases due to a first-order lag system is supplied to the electromagnetic coil (51) constituting the electromagnetic valve (31) ,
The excitation current (S13) actually flowing through the electromagnetic coil (51 ) is detected,
When the exciting current (S13) cannot follow the electrical signal (S12) , the movable iron core (63) attracted by the electromagnetic coil (51) moves, and the valve is directly connected to the movable iron core (63). A drive control method for an electromagnetic valve, characterized in that it is identified as a time when the body (53) opens.

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