JPH0611001U - Pressure proportional controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a pressure proportional control device that stabilizes the operation of a controlled part in a steady state and improves control response. [Structure] In the pressure proportional control device 1, a controlled portion (the solenoid valve 3, the solenoid valve 3,
5) is driven. The pressure proportional controller 1 comprises a deviation means, a reference signal generation means, and a comparison means. The deviation means includes a sensor amplifier 11, a deviation amplifier 13, and a voltage follower 15, which form a deviation signal between the detection signal Sps and the setting signal Spr. The reference signal generating means comprises a triangular wave generator 23 and a waveform clip shaping circuit 25, and clips a part of the top of the reference triangular wave to clip the triangular wave signal S.
get tt. The comparing means is composed of comparators 17 and 21, and an inverting amplifier 19, and forms a PWM control signal from the triangular wave signal Stt and the deviation signal Sd and gives it to the controlled part.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a control device capable of proportionally controlling a fluid pressure, and more particularly to a pressure proportional control device capable of obtaining a desired fluid pressure by adjusting an on / off control time of a solenoid valve.

[0002]

[Prior art]

 In general, PWM is used for current control of motors and heaters. Such a PWM for current control takes in an input signal corresponding to the output current value, compares this input signal with a triangular wave that is a reference signal, and determines the on / off time width of the switching element according to the comparison result. It is intended to obtain a desired current value by adjusting and controlling.

FIG. 5 is a diagram showing a triangular wave used in the PWM. In this figure, the level of the deviation signal Sd between the input signal proportional to the physical quantity corresponding to the output from the PWM and the physical quantity to be set is shown on the positive and negative sides on the vertical axis, and on the positive and negative sides of the deviation signal Sd. An example is shown for each case where PWM control is desired.

That is, in this conventional example, on the positive (+) side of the deviation signal Sd, the deviation signal Sd turns on when the deviation signal Sd on the positive side becomes larger than the value of the reference triangular wave, and the deviation signal Sd becomes larger than the value of the reference triangular wave. It forms a digital signal that turns off when it decreases on the positive side. On the negative (-) side of the deviation signal Sd, it turns on when the deviation signal Sd becomes larger than the value of the reference triangular wave on the negative side, and the deviation signal Sd becomes the reference. It forms a digital signal that turns off when it becomes smaller on the negative side of the triangular wave value. Then, with such an on / off control signal, the value of the physical quantity can be controlled with high accuracy.

FIG. 6 is a system diagram showing an example of a conventional pressure proportional control device that can be controlled by the above-mentioned PWM triangular wave.

The pressure proportional control device 101 shown in FIG. 6 uses two solenoid valves 103 and 105, and controls the on / off time width of these solenoid valves 103 and 105 by a PWM method, thereby fluid such as compressed air. The pressure can be set to a desired value. That is, the pressure proportional control device 101 controls the pressure in the tank 107 by controlling the supply-side electromagnetic valve 103 on / off and the discharge-side electromagnetic valve 105 by the PWM control signal. I try to keep it at the set pressure.

In this pressure proportional control device 101, the PWM control signal is formed as follows. The pressure in the tank 107 is detected by the pressure sensor 109. The pressure detection signal Sps detected by the pressure sensor 109 is amplified by the sensor amplifier 111 and then input to one input terminal of the deviation amplifier 113. The pressure setting signal Spr is amplified by the voltage follower 115 and then input to the other input terminal of the deviation amplifier 113. The deviation amplifier 113 takes the difference between the pressure setting signal Spr and the pressure detection signal Sps to form a deviation signal Sd. The deviation signal Sd is supplied to the supply-side comparator 117 and also to the inverting amplifier 119. The deviation signal Sd ′ inverted by the inversion amplifier 119 is input to the discharge side comparator 121. Further, the reference triangular wave St is input from the triangular wave generator 123 to each of the comparators 117 and 121.

Further, in the pressure proportional control device 101, when the reference triangular wave St is supplied from the triangular wave generator 123, as shown in FIG. 5, the comparator 117, 121 outputs the deviation signals Sd, Sd '. The zero level and the top of the reference triangular wave St are compared. However, when the solenoid valves 103 and 105 are on / off controlled by the PWM control signal obtained as a result of operating the pressure proportional control device 101 in the comparison mode as shown in FIG. 5, the solenoid valves 103 and 105 respond to the solenoid valves 103 and 105. Since there is a delay, the dead zone becomes large and the accuracy of pressure control deteriorates.

Therefore, in order to improve the above problems, there is also known a conventional device in which the pressure proportional control device 101 is improved so that the comparison operation as shown in FIG. 7 becomes possible. That is, in each of the comparators 117 and 121, even when the level of the deviation signals Sd and Sd 'is zero, comparison can be performed in a state where the tops of the reference triangular waves St are overlapped. As a result, the on / off control signals Soa and Sob are turned on even if the level of the deviation signal Sd is zero. As a result, the response delay of the solenoid valves 103 and 105 can be improved, and the accuracy of pressure control can be improved.

[0010]

[Problems to be solved by the device]

 However, according to the above-described conventional pressure proportional control device, as shown in FIG. 7, even if the deviation signal Sd is at the zero level, the solenoid valves 103 and 105 are always on / off controlled. Therefore, since the solenoid valves 103 and 105 are constantly in a vibrating state, the life of each solenoid valve 103, 105 is shortened and noise is generated, and a current flows through each solenoid valve 103, 105 in a steady state. However, there is a drawback that the current consumption increases.

An object of the present invention is to provide a pressure proportional control device that improves the above-mentioned drawbacks, stabilizes the operation of a controlled part in a steady state, and improves control response.

[0012]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the pressure proportional control device of the present invention adjusts the physical quantity by controlling the drive of the controlled part so as to match the set signal based on the signal from the sensor that detects the physical quantity. In a pressure proportional control device, a deviation means for obtaining a deviation signal between the detection signal from the sensor and the setting signal, and a reference signal generation for clipping a part of the top of the generated reference triangular wave to obtain a clipped triangular wave signal Means for comparing the clipped triangular wave signal from the reference signal generating means with the deviation signal to form a PWM control signal and supply the PWM control signal to the controlled unit. .

[0013]

Therefore, the pressure proportional control device of the present invention detects the physical quantity with the sensor, and drives and controls the controlled part so that the detection signal matches a predetermined set value. The controlled part is driven and controlled by the PWM control signal from the pressure proportional controller. The PWM control signal uses the clipped triangular wave signal from the reference signal generating means as the reference signal, and compares the deviation signal from the deviation means with the clipped triangular wave signal by the comparison means. Then, since the clipped triangular wave signal is flattened by clipping a part of its top, when the deviation signal is at zero level, the PWM control signal is not formed even when compared with the clipped triangular wave signal. However, when the deviation signal exceeds the zero level, the comparison with the clipped triangular wave signal becomes possible immediately. Therefore, the operation that compensates for the response delay of each solenoid valve becomes possible.

[0014]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show an embodiment of the pressure proportional controller of the present invention.

FIG. 1 is a configuration diagram of a main part of a pressure proportional controller according to an embodiment of the present invention.

In FIG. 1, the pressure proportional control device 1 controls the fluid supply side solenoid valve 3 and the fluid discharge side solenoid valve 5 to be turned on and off by a PWM control signal to set the pressure of the fluid filled in the tank 7 to a pressure setting signal. The pressure of Spr can be maintained and the fluid output from the tank 7 can be stably supplied.

The fluid system includes a small-capacity tank 7 that keeps the pressure constant, a pipe 4 that can supply the fluid from the fluid supply source W to the tank 7, and a fluid supply side electromagnetic valve provided in the middle of the pipe 4. It comprises a valve 3, a pipe 6 for discharging the fluid accumulated in the tank 7 to the atmosphere, and a fluid discharge side solenoid valve 5 provided in the middle of the pipe 6.

Further, the pressure proportional control device 1 includes a pressure sensor 9, a sensor amplifier 11, a deviation amplifier 13, a voltage follower 15, a supply side comparator 17, an inverting amplifier 19, a discharge side comparator 21, a triangular wave generator 23, The waveform clip shaping circuit 25 is provided and is configured as follows.

Here, the sensor amplifier 11, the deviation amplifier 13, and the voltage follower 15 constitute a deviation means. This deviation means can obtain a deviation signal between the detection signal Sps from the pressure sensor 9 and the pressure setting signal Spr.

Further, the triangular wave generator 23 and the waveform clip shaping circuit 25 constitute a reference signal generating means. This reference signal generating means is a characteristic of the present invention in which the reference triangle wave St generated by the triangle wave generator 23 is clipped by the waveform clip shaping circuit 25 to partially flatten the top portion of the reference triangle wave St. A triangular wave signal Stt can be obtained.

The supply side comparator 17, the inverting amplifier 19, and the discharge side comparator 21 constitute a comparison means. The comparing means can compare the clipped triangular wave signal Stt from the reference signal generating means with the deviation signal Sd to form a PWM control signal and supply the PWM control signal to the controlled part.

The fluid supply side solenoid valve 3 and the fluid discharge side solenoid valve 5 constitute a controlled part. This controlled unit can adjust the pressure of the fluid, which is a physical quantity.

The structure of the pressure proportional control device 1 will be described below in detail. The pressure sensor 9 is fixed to the tank 7, and the pressure of the tank 7 is detected to obtain the pressure detection signal Sps. It is designed to output. The output of the pressure sensor 9 is connected to the input terminal of the sensor amplifier 11 so that the pressure detection signal Sps from the pressure sensor 9 can be supplied to the sensor amplifier 11. The sensor amplifier 11 is a circuit that can amplify and output the pressure detection signal Sps. The output of the sensor amplifier 11 is connected to one input terminal of the deviation amplifier 13. Further, the pressure setting signal S pr is supplied to the voltage follower 15. The voltage follower 15 is a circuit that amplifies the pressure setting signal Spr. The output of the voltage follower 15 is connected to the other input terminal of the deviation amplifier 13, and supplies the pressure setting signal Spr from the voltage follower 15 to the deviation amplifier 13. The deviation amplifier 13 is configured to take the difference between the pressure setting signal Spr and the pressure detection signal from the sensor amplifier 11 to form a deviation signal Sd. The output terminal of the deviation amplifier 13 is connected to the comparison-side input terminal of the supply-side comparator 17 and the input terminal of the inverting amplifier 19. The inverting amplifier 19 is configured to invert the polarity of the input deviation signal Sd to obtain the deviation signal Sd '. The inverted deviation signal Sd 'of the inverting amplifier 19 is connected to the comparison side input terminal of the discharge side comparator 21 so as to perform the reverse operation.

The triangular wave generator 23 is also configured to generate the reference triangular wave St. The output of the triangular wave generator 23 is connected to the input terminal of the waveform clip shaping circuit 25 so that the reference triangular wave St from the triangular wave generator 23 can be supplied to the waveform clip shaping circuit 25.

As shown in FIG. 3, the waveform clip shaping circuit 25, which is one of the features of the present invention, outputs a clipped triangular wave signal Stt obtained by clipping a part of one apex of the input reference triangular wave St. The circuit is configured so that it can be formed. The output of the waveform clip shaping circuit 25 is connected to the reference side input terminals of the supply side comparator 17 and the discharge side comparator 21.

The supply side comparator 17 compares the clip triangular wave signal Stt supplied from the waveform clip shaping circuit 25 with the deviation signal Sd from the deviation amplifier 13 to form an on-off control signal Soa. It is composed. The discharge side comparator 21 compares the clipped triangular wave signal Stt supplied from the waveform clip shaping circuit 25 with the inverted deviation signal Sd ′ from the inversion amplifier 19 to form an on / off control signal Sob. Has become. The on / off control signal Soa from the supply side comparator 17 is supplied to the electromagnetic coil of the fluid supply side solenoid valve 3, and the fluid supply side solenoid valve 3 can be on / off controlled. The on / off control signal Sob from the discharge side comparator 21 is supplied to the electromagnetic coil of the fluid discharge side solenoid valve 5, and the fluid discharge side solenoid valve 5 can be on / off controlled.

FIG. 2 is a circuit diagram showing a specific configuration example of the waveform clip shaping circuit 25, which is one of the features of the present invention.

In FIG. 2, the waveform clip shaping circuit 25 includes a resistor R, a Zener diode ZD, and a voltage follower Q composed of an operational amplifier, and has a circuit configuration as follows. A series circuit of a resistor R and a Zener diode ZD is connected between the input terminals Ti. Both ends of the Zener diode ZD are connected to the non-inverting input terminal of the operational amplifier of the voltage follower Q. The voltage follower Q 3 is formed by directly connecting the inverting input terminal and the output terminal of the operational amplifier. The voltage follower Q takes out an output signal from the output terminal of the operational amplifier and outputs it from the output terminal To of the waveform clip shaping circuit 25.

The characteristic operation of such an embodiment will be described below.

The triangular wave generator 23 outputs a reference triangular wave St as shown in FIG. This reference triangular wave St is applied to the input terminal Ti of the waveform clip shaping circuit 25, and the clipping circuit composed of the resistor R and the Zener diode ZD in the waveform clip shaping circuit 25 causes one of the top portions of the reference triangular wave St to have a predetermined value. It is cut out and shaped into a clipped triangular wave signal Stt having a flat top. The clipped triangular wave signal Stt is amplified by the voltage follower Q and output as an output signal of the waveform clip shaping circuit 25 from the output terminal To. The clipped triangular wave signal Stt from the waveform clip shaping circuit 25 is supplied to the supply side comparator 17 and the discharge side comparator 21.

The pressure inside the tank 7 is detected by the pressure sensor 9. The pressure detection signal Sps detected and output by the pressure sensor 9 is amplified by the sensor amplifier 11. The output signal from the sensor amplifier 11 is input to the deviation amplifier 13. Further, the pressure setting signal Spr is input to the deviation amplifier 13 via the voltage follower 15. The deviation amplifier 13 takes the difference between the two signals to form the deviation signal Sd. The deviation signal Sd is supplied to the supply side comparator 17 and the inverting amplifier 19. The inverting amplifier 19 inverts the polarity of the input deviation signal Sd to form an inversion deviation signal Sd '. The inverted deviation signal Sd ′ is applied to the discharge side comparator 21.

<Operation with Zero Level of Deviation Signal Sd> In the supply side comparator 17, as shown in FIG. 4, when the deviation signal Sd is zero level, it corresponds to a flat shape part of the clip part of the clip triangular wave signal Stt. Therefore, the on / off control signal Soa is not output. Similarly, in the discharge side comparator 21, as shown in FIG. 4, when the inversion deviation signal Sd ′ is at the zero level, it corresponds to the flat shape portion of the clip portion of the clip triangular wave signal Stt, and thus the on-off state. The control signal Sob is not output.

<Operation of Negative Level of Deviation Signal Sd> Further, when the pressure detection signal Sps is larger than the pressure setting signal Spr, the deviation signal Sd output from the deviation amplifier 13 becomes negative. Therefore, the supply side comparator 17 cannot compare with the clip triangular wave signal Stt, and therefore the on / off control signal Soa is at the off level. On the other hand, the discharge side comparator 21 can compare the inverted deviation signal Sd ′ from the inverting amplifier 19 with the clipped triangular wave signal Stt, and the inverted deviation signal Sd ′ becomes a value larger than the value of the clipped triangular wave signal Stt. It outputs an on / off control signal Sob which is turned on when it is turned on and turned off when it is turned off. The ON width of the ON / OFF control signal Sob becomes wider as the inversion deviation signal Sd 'becomes larger. As a result, the fluid discharge side solenoid valve 5 is on / off controlled, and the fluid inside the tank 7 is discharged to the atmosphere via the pipe 6. This discharge is continued until the fluid pressure in the tank 7 becomes the same as the pressure setting signal Spr. As a result, the pressure of the fluid inside the tank 7 is adjusted to a constant value.

As described above, in this embodiment, since the top of the clipped triangular wave signal Stt is missing, when the inverted deviation signal Sd ′ changes from the zero level, the comparison operation is immediately performed, and the fluid discharge side solenoid valve is operated. The response delay of 5 can be compensated.

<Operation of Positive Level of Deviation Signal Sd> Further, when the pressure detection signal Sps is smaller than the pressure setting signal Spr, the deviation signal Sd output from the deviation amp 13 becomes positive. Therefore, in the discharge side comparator 21, the inverted deviation signal Sd 'from the inverting amplifier 19 becomes negative and cannot be compared with the clipped triangular wave signal Stt, so the on / off control signal Sob is at the off level. On the other hand, the supply-side comparator 17 can compare with the clipped triangular wave signal Stt, and is turned on when the deviation signal Sd becomes larger than the value of the clipped triangular wave signal Stt, and vice versa. An on-off control signal S oa that turns off is output. The ON width of the ON / OFF control signal Soa becomes wider as the deviation signal Sd becomes larger. As a result, the fluid supply side solenoid valve 3 is on / off controlled, and the fluid is supplied from the fluid supply source W to the tank 7 via the pipe 4. This supply is continued until the fluid pressure in the tank 7 becomes the same as the pressure setting signal Spr. As a result, the pressure of the fluid inside the tank 7 is adjusted to a constant value. In this way, in this embodiment, since the top of the clipped triangular wave signal Stt is missing, when the deviation signal S d changes from the zero level, the comparison operation is immediately performed, and the response delay of the fluid supply side solenoid valve 3 is delayed. Can be compensated.

When the pressure proportional control device 1 controls the fluid supply side solenoid valve 3 and the fluid discharge side solenoid valve 5 to turn on and off, and the pressure in the tank 7 reaches a constant value (pressure setting signal Spr), It becomes the state of 4 and becomes the steady state.

In this embodiment, since the fluid pressure in the tank 7 is adjusted by operating as described above, the solenoid valves 3 and 5 do not operate in a steady state, and the life of the solenoid valves 3 and 5 is extended. Since power is not supplied to the solenoid valves 3 and 5 in the steady state, power consumption can be reduced, and no operation noise is generated from the solenoid valves 3 and 5 in the steady state.

Further, in the embodiment of the present invention, the deviation signal Sd and the inverted deviation signal Sd ′ thereof are used to compare with the clipping triangular wave signal Stt, but in short, the deviation using the clipping triangular wave signal Stt is used. Any device that obtains a PWM control signal by comparing with the signal Sd or the like falls within the scope of the present invention.

[0040]

[Effect of device]

 As described above, according to the present invention, the controlled triangular wave signal is used, the controlled part is not operated in the steady state, and the PWM controlled signal is immediately generated to operate the controlled part in the unsteady state. By doing so, there is an effect that the life of the controlled part is extended, the power consumption is reduced because no current flows, the noise is not generated from the controlled part, and the control response is quick.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a pressure proportional controller according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration example of a waveform clip shaping circuit used in an embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining the operation of the waveform clip shaping circuit used in the embodiment of the present invention.

FIG. 4 is a waveform diagram for explaining the operation of the embodiment of the present invention.

FIG. 5 is an explanatory diagram for obtaining a conventional PWM waveform.

FIG. 6 is a system diagram of a conventional pressure proportional controller.

FIG. 7 is an operation explanatory view of a conventional pressure proportional control device.

[Explanation of symbols]

 1 Pressure proportional control device 3 Fluid supply side solenoid valve 5 Fluid discharge side solenoid valve 7 Tank 9 Pressure sensor 11 Sensor amplifier 13 Deviation amplifier 15 Voltage follower 17 Supply side comparator 19 Inversion amplifier 21 Discharge side comparator 23 Triangular wave generator 25 Waveform clip shaping circuit

Claims (1)

[Scope of utility model registration request] 1. A pressure proportional control device for driving and controlling a controlled part so as to match a predetermined setting signal based on a signal from a sensor for detecting a physical quantity, and detecting the sensor. Deviation means for obtaining a deviation signal between the signal and the setting signal, reference signal generating means for obtaining a clipped triangular wave signal by clipping a part of the apex of the generated reference triangular wave, and a clipped triangular wave signal from the reference signal generating means A pressure proportional control device, comprising: a comparison unit that compares the deviation signal to generate a PWM control signal and supplies the PWM control signal to the controlled unit.