Spool valve

Patent metadata

Field	Value
Publication number	US-12044331-B2
Application number	US-202017911099-A
Country	US
Kind code	B2
Filing date	Dec 28, 2020
Priority date	Mar 12, 2020
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

Abstract

A spool is slidably located in a slide hole of a first housing. A second housing forms a servo chamber that is coaxial with the slide hole. A sleeve is slidably located in the servo chamber. A nut is fixed to a piston that is slidably fitted in the sleeve. An electric motor rotates a screw shaft screwed with the nut. The second housing includes an input port and a drain port. A first pressure chamber communicates with the input port. In a balanced state where forces applied to the sleeve from both sides are balanced, a second pressure chamber is blocked from the input port and the drain port by the piston. From the balanced state, when the piston shifts, the second pressure chamber comes into communication with the input port or the drain port.

First claim

The invention claimed is:

1. A spool valve comprising:
a first housing including passages and a slide hole;
a spool slidably located in the slide hole;
a second housing that forms a servo chamber that is coaxial with the slide hole;
a sleeve slidably located in the servo chamber, the sleeve dividing the servo chamber into a first pressure chamber and a second pressure chamber, the first pressure chamber being adjacent to the first housing, the second pressure chamber being away from the first housing, the sleeve being coupled to the spool in the first pressure chamber;
a piston slidably fitted in the sleeve and extending from inside the sleeve beyond the second pressure chamber;
a nut fixed to the piston;
a screw shaft screwed with the nut;
an electric motor that rotates the screw shaft; and
a coil spring within which the nut is positioned, the coil spring applying an urging force to the piston to keep the spool at a neutral position thereof, wherein
the second housing includes a drain port and an input port that is to be connected to a pressure source of a hydraulic fluid,
the first pressure chamber communicates with the input port,
in a balanced state where a force that is applied to the sleeve by the hydraulic fluid in the first pressure chamber, and a force that is applied to the sleeve by the hydraulic fluid in the second pressure chamber, are balanced, the second pressure chamber is blocked from the input port and the drain port by the piston,
from the balanced state, when the piston shifts in a direction toward the spool, the second pressure chamber comes into communication with the input port, and
from the balanced state, when the piston shifts in a direction away from the spool, the second pressure chamber comes into communication with the drain port.

Assignees

• Kawasaki Heavy Ind Ltd

Inventors

• Tanaka Hideki
• Aoki Seiji

Classifications

• F16K31/508

  the actuating element being rotatable, non-rising, and driving a non-rotatable axially-sliding element · CPC title

• F16K31/047 Primary

  characterised by mechanical means between the motor and the valve, e.g. lost motion means reducing backlash, clutches, brakes or return means (F16K31/043 takes precedence) · CPC title

• F16K11/07

  with cylindrical slides · CPC title

• F15B13/0444

  with rotary electric motor · CPC title

• F15B13/0435

  the pilot valves being sliding valves · CPC title