KR-102961915-B1 - Fluid control valve, flow rate control device, and drive circuit

KR102961915B1KR 102961915 B1KR102961915 B1KR 102961915B1KR-102961915-B1

Abstract

In order to provide a fluid control valve capable of suppressing heat generation when contracting by discharging charge from a piezo actuator and reducing the energy required to drive the piezo actuator, the fluid control valve (3) comprises a piezo actuator (31) and a driving circuit (32) connected to the piezo actuator (31), wherein the driving circuit (32) comprises a flyback transformer (5) having a primary coil (51) connected to a DC power source DV and a secondary coil (52) connected to the piezo actuator (31), a charging switch (61) connected to the primary coil (51) and switched from on to off when the piezo actuator (31) is charged, a discharge switch (62) connected to the secondary coil (52) and switched from off to on when the piezo actuator (31) is discharged, and the A regenerative capacitor (71) is provided that is connected to the primary coil (51) and regenerates electrical energy from the discharge of the piezo actuator (31).

Inventors

랜스델 제프리
도쿠나가 가즈야

Assignees

가부시키가이샤 호리바 에스텍

Dates

Publication Date: 20260507
Application Date: 20240523
Priority Date: 20190607

Claims (2)

A fluid control valve comprising a piezo actuator and a driving circuit connected to the piezo actuator, The above driving circuit comprises a charging circuit for charging the piezo actuator and a discharge circuit for discharging the piezo actuator, and The charging circuit described above comprises a Darlington connection consisting of multiple NPN transistors, a resistor provided between the high-voltage side of the piezo actuator and the emitter of the NPN transistor at the end of the Darlington connection, and is configured such that current is supplied to the piezo actuator from the emitter of the end. The above discharge circuit comprises a control switch which is an NPN transistor and a PNP transistor, and The above control switch has its collector connected to the base of the first stage NPN transistor of the Darlington connection and its emitter connected to the low-voltage side of the piezo actuator. The above PNP transistor has its emitter connected to the emitter of the NPN transistor at the final stage of the Darlington connection, its base connected to the base of the NPN transistor at the first stage of the Darlington connection, and its collector connected to the low-voltage side of the piezo actuator. A fluid control valve characterized in that when the control switch is off, the piezo actuator is charged by the Darlington connection, and when the control switch is on, the piezo actuator is discharged by the resistor and the PNP transistor.
As a driving circuit connected to a piezo actuator, The apparatus comprises a charging circuit for charging the piezo actuator and a discharge circuit for discharging the piezo actuator. The charging circuit described above comprises a Darlington connection consisting of multiple NPN transistors, a resistor provided between the high-voltage side of the piezo actuator and the emitter of the NPN transistor at the end of the Darlington connection, and is configured such that current is supplied to the piezo actuator from the emitter of the end. The above discharge circuit comprises a control switch which is an NPN transistor and a PNP transistor, and The above control switch has its collector connected to the base of the first stage NPN transistor of the Darlington connection and its emitter connected to the low-voltage side of the piezo actuator. The above PNP transistor has its emitter connected to the emitter of the NPN transistor at the final stage of the Darlington connection, its base connected to the base of the NPN transistor at the first stage of the Darlington connection, and its collector connected to the low-voltage side of the piezo actuator. A driving circuit characterized in that when the control switch is off, the piezo actuator is charged by the Darlington connection, and when the control switch is on, the piezo actuator is discharged by the resistor and the PNP transistor.

Description

Fluid control valve, flow rate control device, and drive circuit The present invention relates to a fluid control valve equipped with a piezo actuator used to control the pressure or flow rate of a fluid. For example, in a semiconductor manufacturing process, the flow rate of gas supplied into a chamber is controlled by a mass flow controller. This mass flow controller is equipped with a fluid control valve, for example, equipped with a piezo actuator, and a flow sensor. The voltage applied to the piezo actuator is controlled so that the difference between the measured flow rate measured by the flow sensor and the set flow rate set by the user is reduced (see Patent Document 1). However, when voltage is applied to a piezo actuator and it contracts from an extended state, it is necessary to discharge the charge accumulated in the piezo actuator. Conventionally, the charge discharged from the piezo actuator is consumed as heat, for example, in a resistor in a driving circuit. However, in cases where the supply and stoppage of gas are repeated at high speed, such as in the ALD process, not only is this energy waste significant, but the amount of heat generated by the piezo actuator also increases, raising concerns that it may affect the final flow control characteristics. FIG. 1 is a schematic diagram showing a fluid control device using a fluid control valve according to a first embodiment of the present invention. FIG. 2 is a schematic circuit diagram showing a driving circuit of a fluid control valve according to a first embodiment. FIG. 3 is a schematic circuit diagram showing a driving circuit of a fluid control valve according to a second embodiment. FIG. 4 is a schematic circuit diagram showing a charging circuit of a driving circuit according to a second embodiment. FIG. 5 is a schematic circuit diagram showing a discharge circuit of a driving circuit according to a second embodiment. A fluid control valve (3) according to the first embodiment of the present invention will be described with reference to FIGS. 1 and FIGS. 2. The fluid control valve (3) of the first embodiment is used in a mass flow controller (100) that controls the flow rate of fluid in, for example, a semiconductor manufacturing process. As shown in FIG. 1, the mass flow controller (100) is a package comprising various fluid devices including the fluid control valve (3) and a control board (B) responsible for controlling the fluid control valve (3). Specifically, the mass flow controller (100) has a block (1) in which a fluid path (C) is formed inside, and the fluid control valve (3), upstream pressure sensor (21), laminar flow element (22), and downstream pressure sensor (23) are mounted on this block (1). In addition, the control board (B) is a so-called computer equipped with a CPU, memory, A/D converter, D/A converter, and various input/output devices, and performs functions as at least a flow rate calculation unit (24) and a valve control unit (4) by executing a program stored in memory. The flow rate calculation unit (24) calculates the flow rate of the fluid flowing within the block (1) from each measured pressure measured by the upstream pressure sensor (21) and the downstream pressure sensor (23). That is, the upstream pressure sensor (21), the laminar flow element (22), the downstream pressure sensor (23), and the flow rate calculation unit (24) constitute a so-called pressure-type flow rate sensor (2). Additionally, the flow rate calculation formula used in the flow rate calculation unit (24) may be an existing one. Furthermore, the flow rate calculated by the flow rate calculation unit (24) is output to the valve control unit (4) as the measured flow rate. The valve control unit (4) controls the opening of the fluid control valve (3) with flow rate feedback so that the difference between the set flow rate set by the user and the measured flow rate calculated by the flow rate calculation unit (24) becomes smaller. In the first embodiment, the valve control unit (4) is a PID controller that receives the difference between the set flow rate and the measured flow rate and outputs a voltage command to be applied to the flow rate control valve by PID calculation. The flow control valve comprises a valve seat, a valve body that displaces relative to the valve seat, a piezo actuator (31) that displaces the valve body, and a driving circuit (32) that drives the piezo actuator (31). The piezo actuator (31) is, for example, a piezo element and an electrode stacked alternately. The piezo actuator (31) changes in length according to the voltage applied by the driving circuit (32). The driving circuit (32) is a DC/DC converter equipped with a flyback transformer (5), a charging switch (61), a discharging switch (62), a regenerative capacitor (71), a diode (73), and an output capacitor (72) as shown in FIG. 2, and controls the charging and discharging of the piezo actuator (31). In addition, the driving circuit (32) is configured so that