JP2015124835A - Solenoid valve drive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive circuit used for drive of a solenoid valve used in flow passage changeover with a liquid chromatograph method or the like, and capable of making a switching element for drive into a single structure without voltage limit resistance.SOLUTION: A solenoid valve is driven by using a solenoid valve drive circuit that includes a programmable logic device provided with: a setting resister setting parameters on a control frequency, a duty and a solenoid valve startup time; and a control logic performing PWM control with the parameters.

Description

  The present invention relates to a solenoid valve drive circuit that activates and holds a solenoid valve.

  When the solenoid valve used for channel switching such as liquid chromatography is continuously driven, the solenoid valve itself generates heat. It is necessary to prevent the heat from affecting the temperature of the liquid passing through the flow path. For this reason, as a countermeasure against heat generation of the electromagnetic valve, conventionally, for example, a configuration in which a voltage limiting resistor is added to the drive circuit as shown in FIG. As shown in FIG. 2, the solenoid valve starting current and the holding current are controlled to be driven in parallel, and the applied voltage is lowered after a certain starting time.

In the case of the configuration as shown in FIG. 1, since heat is generated in the limiting resistor by passing a current through the voltage limiting resistor, it is necessary to consider exhaust heat. Further, as shown in FIG. 1, two switching (SW) elements for driving are required for starting and holding. Furthermore, since the holding voltage (holding current) is a fixed value, if the holding voltage is changed according to the viscosity or flow velocity of the liquid flowing in the flow path, the limiting resistor must be replaced with another constant value. I must. As described above, various problems have been found in the conventional solenoid valve drive circuit.

As a result of intensive studies on the above problems, the present inventors have reached the present invention. That is, the present invention includes a setting register in which parameters related to control frequency, duty, and solenoid valve activation time are set,
Control logic for performing PWM control according to the parameters;
It is a solenoid valve drive circuit provided with the programmable logic device which provided.

  The present invention is described in further detail below.

  As the programmable logic device used in the present invention, for example, a logic device such as a field programmable gate array (FPGA) is suitable. Such a logic device can constitute a control circuit in one chip. By implementing pulse width modulation (PWM) control for driving an electromagnetic valve with a programmable logic device, for example, as shown in FIG. 3, no voltage limiting resistor is required, and a single drive switching (SW) element is driven. A circuit can be configured, and as a result, heat generation of the solenoid valve itself when continuously driven can be suppressed, and the number of components and mounting area can be reduced.

  Specifically, as shown in FIG. 4, the control circuit can be configured by a setting register and control logic that can be accessed from the CPU as needed. As this CPU, a CPU for controlling a measuring device equipped with an electromagnetic valve, for example, a liquid chromatograph device, can be used. This control circuit is set for a control frequency register for setting an appropriate PWM frequency according to the characteristics specific to the solenoid valve, a duty register for setting a duty, and a start time for setting a start time. This is possible by inputting parameters to the registers from the CPU. The control logic generates the timing of the control signal of the start time and duty (Duty) as shown in FIG. 5 by the input of the register value to which these parameters are input and the control start signal (SV on). It is.

  Further, since the setting register and the control logic can be accessed from the CPU as described above, the setting can be changed in a programmable manner in accordance with the viscosity or flow velocity of the liquid flowing through the electromagnetic valve or the flow path to be used.

  The PWM basic frequency, duty, and start-up time can be set arbitrarily, but the duty is preferably 50 to 100%, more preferably about 70%.

  An electromagnetic valve can be driven using such a drive circuit. At that time, it is preferable to set the start-up time and the PWM frequency in consideration of characteristics (inductance and the like) unique to the solenoid valve. The electromagnetic valve is not particularly limited, and examples thereof include a two-way valve and a three-way valve that are used for channel switching such as a chromatographic method.

  According to the present invention, heat generation at the time of using a solenoid valve in continuous drive can be suppressed so as not to affect the liquid temperature passing through the flow path, and the number of components and mounting area can be reduced compared to a conventional drive circuit. . In addition, the control circuit is configured with a setting register and control logic, which can be realized in one chip, and the values of the parameters “control frequency”, “duty” and “start-up time” set in the setting register are Programmable settings can be made according to characteristics, fluid viscosity, and flow velocity.

It is a figure which shows the structure of the conventional drive circuit. It is a figure which shows the timing of control in the conventional drive circuit. It is a figure which shows an example of the drive circuit by this invention. It is a block diagram which shows an example of the control circuit by this invention. It is a figure which shows an example of the timing of control in the drive circuit by this invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

[Example 1]
In this example, the drive circuit shown in FIG. 3 was produced. This has a control circuit composed of a setting register and control logic shown in FIG. In this embodiment, the starting time is set to 100 ms, the holding voltage is set to Duty 70%, and the frequency is set to 50 KHz in consideration of the inductance of the solenoid valve. The control timing is shown in FIG. 5 in contrast to the case of Duty 100% (same as Duty in the starting time).

Claims (1)

A setting register in which parameters related to control frequency, duty and solenoid valve activation time are set;
Control logic for performing PWM control according to the parameters;
An electromagnetic valve drive circuit comprising a programmable logic device provided with

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