Vacuum valve and valve control device

Patent metadata

Field	Value
Publication number	US-11035488-B2
Application number	US-201916664829-A
Country	US
Kind code	B2
Filing date	Oct 26, 2019
Priority date	Dec 20, 2018
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

A vacuum valve for driving a valve body arranged facing a valve opening up and down relative to the valve opening to perform valve opening/closing operation, comprises: a first up-down driver configured to drive the valve body up and down with a first minimum drivable amount; and a second up-down driver configured to drive the valve body up and down with a second minimum drivable amount smaller than the first minimum drivable amount.

First claim

What is claimed is:

1. A vacuum valve for driving a valve body arranged facing a valve opening up and down relative to the valve opening to perform valve opening/closing operation, comprising:
a first up-down driver configured to drive the valve body up and down with a first minimum drivable amount;
a second up-down driver configured to drive the valve body up and down with a second minimum drivable amount smaller than the first minimum drivable amount, the second up-down driver being a magnetic levitation actuator configured to magnetically levitate and support the valve body in an up-down drive direction; and
a valve control device, including:
a first controller configured to control up-down drive by the first up-down driver by open loop control based on a pressure target value and a pressure measurement value of a chamber subjected to vacuum-pumping through the vacuum valve; and
a second controller configured to control up-down drive of the second up-down driver by closed loop control or up-down drive of the first and second up-down drivers by closed loop control, based on the pressure target value and the pressure measurement value of the chamber subjected to vacuum-pumping through the vacuum valve.

2. The vacuum valve control device according to claim 1 , wherein the second controller controls the up-down drive by the second up-down driver based on the pressure target value and the pressure measurement value after the up-down drive by the first up-down driver.

3. A vacuum valve for driving a valve body arranged facing a valve opening up and down relative to the valve opening to perform valve opening/closing operation, comprising:
a first up-down driver configured to drive the valve body up and down with a first minimum drivable amount;
a second up-down driver configured to drive the valve body up and down with a second minimum drivable amount smaller than the first minimum drivable amount, the second up-down driver being a magnetic levitation actuator configured to magnetically levitate and support the valve body in an up-down drive direction; and:
a valve control device, including:
a first controller configured to control up-down drive by the first up-down driver by open loop control based on a pressure target value and a pressure measurement value of a chamber subjected to vacuum-pumping through the vacuum valve; and
a second controller configured to control up-down drive by the second up-down driver by closed loop control based on the pressure target value and the pressure measurement value of the chamber subjected to vacuum-pumping through the vacuum valve,
wherein the second controller drives, when the vacuum valve is fully closed, the valve body in a direction of a valve seat by the magnetic levitation actuator, and with predetermined force, presses the valve body against a seal member provided between the valve body and the valve seat.

4. The vacuum valve according to claim 1 , wherein the first up-down driver is a linear actuator using a ball screw to be driven by a stepping motor.

5. The vacuum valve according to claim 4 , wherein the linear actuator includes:
a ball screw nut provided at a slider fixed to the second up-down driver,
a coupling,
a threaded rod screwed into the ball screw nut, threaded rod being joined to a rotor shaft of the stepping motor by the coupling, and
the slider supported by a support to slide in a z-axis direction.

6. The vacuum valve according to claim 1 , wherein the magnetic levitation actuator includes:
an upper electromagnet, a lower electromagnet and an axial disc magnetically levitated and supported in a z-axis direction by the upper electromagnet and the lower electromagnet.

7. A vacuum valve for driving a valve body arranged facing a valve opening up and down relative to the valve opening to perform valve opening/closing operation, comprising:
a first up-down driver configured to drive the valve body up and down with a first minimum drivable amount; and
a second up-down driver configured to drive the valve body up and down with a second minimum drivable amount smaller than the first minimum drivable amount, the second up-down driver being a magnetic levitation actuator configured to magnetically levitate and support the valve body in an up-down drive direction, wherein
the magnetic levitation actuator includes:
an upper electromagnet, a lower electromagnet and an axial disc magnetically levitated and supported in a z-axis direction by the upper electromagnet and the lower electromagnet;
a sensor target provided on the lower surface of the axial disc; and
an axial gap sensor provided facing the sensor target, and detecting displacement of the axial disc in the z-axis direction.

8. The vacuum valve according to claim 6 , further comprising:
a linear ball bearing provided at a body case and,
a valve rod fastened to the axial disc, and supported by the linear ball bearing to move in the z-axis direction, wherein
the valve rod extends to a vacuum chamber side through a valve seat, and the valve body arranged in the vacuum chamber is fixed to an upper end of the valve rod.

9. The vacuum valve according to claim 8 , wherein:
a bellows is provided between the valve rod and the valve seat such that no gas enters the vacuum chamber through a clearance between a through-hole of the valve seat and the valve rod.

10. A vacuum valve for driving a valve body arranged facing a valve opening up and down relative to the valve opening to perform valve opening/closing operation, comprising:
a first up-down driver configured to drive the valve body up and down with a first minimum drivable amount; and
a second up-down driver configured to drive the valve body up and down with a second minimum drivable amount smaller than the first minimum drivable amount, the second up-down driver being a magnetic levitation actuator configured to magnetically levitate and support the valve body in an up-down drive direction;
wherein the first up-down driver is a linear actuator using a ball screw to be driven by a stepping motor,
a position accuracy of the linear actuator is ΔLa1+ΔLa2, ΔLa1 being a minimum displacement of a valve rod according to a step angle of the stepping motor, ΔLa2 being a maximum value of a displacement error due to backlash of the stepping motor, and
the magnetic levitation actuator is configured so that displacement of a valve rod can be adjusted by ΔLa1+ΔLa2.

11. The vacuum valve according to claim 1 , wherein:
the second up-down driver has a position accuracy for positioning the valve body with a smaller movement amount than a movement amount indicating a position accuracy of the first up-down driver.

Assignees

• Shimadzu Corp

Inventors

• Kozaki Junichiro

Classifications

• F16K1/00 Primary

  Lift valves {or globe valves}, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces ({in combination with sliding valves F16K3/246, F16K3/267} ; diaphragm valves F16K7/00) · CPC title

• F16K31/04

  using a motor · CPC title

• F16K51/02 Primary

  specially adapted for high-vacuum installations · CPC title

• F16K37/005

  for measuring fluid parameters (F16K37/0033 takes precedence) · CPC title

• F16K31/0655

  Lift valves · CPC title