Servo valve

Patent metadata

Field	Value
Publication number	US-10697477-B2
Application number	US-201815956369-A
Country	US
Kind code	B2
Filing date	Apr 18, 2018
Priority date	Dec 8, 2017
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A servo valve is provided with a first elastic portion, a second elastic portion, and a connecting portion. The first elastic portion extends in an X direction inside a valve body and has a first elastic force exerted on a movable element toward an X2 direction. The second elastic portion extends in the X direction inside the valve body and has a second elastic force exerted on the movable element toward an X1 direction. The connecting portion is connected to the first elastic portion and the second elastic portion inside the valve body, and is in abutment against a step portion of the valve body and a spool of the movable element at a neutral position of the movable element.

First claim

What is claimed is:

1. A servo valve comprising a tubular body including a plurality of ports formed therein; a movable element disposed inside the tubular body in an axial direction of the tubular body; and a drive unit connected to the tubular body in the axial direction and configured to slide the movable element in the axial direction to thereby switch connections of flow passages between the ports, the servo valve further comprising:
a first elastic portion extending in the axial direction inside the tubular body and having a first elastic force to press the movable element toward the drive unit in the axial direction;
a second elastic portion extending in the axial direction inside the tubular body and having a second elastic force to press the movable element in a direction away from the drive unit along the axial direction; and
a connecting portion connected to at least the second elastic portion inside the tubular body, wherein at a neutral position of the movable element at which driving of the drive unit is stopped, the connecting portion abuts against a portion of the tubular body that faces the drive unit and a portion of the movable element that faces the drive unit, wherein:
one end of the first elastic portion is fixed to the movable element;
one end of the second elastic portion is fixed to the tubular body; and
another end of the first elastic portion and another end of the second elastic portion are both connected to portions of the connecting portion facing in the same direction with respect to the drive unit.

2. The servo valve according to claim 1 , wherein:
the drive unit includes a tubular body comprising a magnetic body and connected to the tubular body in the axial direction, and a movable portion provided inside the tubular body and forming a portion of the movable element, the movable portion including a movable magnet, a movable coil or a movable iron core; and
by moving the movable portion in the axial direction, the movable element including the movable portion is slid in the axial direction.

3. The servo valve according to claim 2 , wherein:
the drive unit has a first yoke, which serves as the tubular body, connected to the tubular body in the axial direction, a coil disposed inside the first yoke, and a magnet portion, which serves as the movable portion, provided inside the first yoke so as to face the coil; and
a magnetic attractive force exerted on the magnet portion due to energization to the coil causes the movable element to slide in the axial direction.

4. The servo valve according to claim 3 , wherein:
protruding portions protruding inward of the first yoke are provided respectively at one end side and another end side of the first yoke in the axial direction; and
at the neutral position at which energization to the coil is stopped, the magnet portion is positioned between the two protruding portions.

5. The servo valve according to claim 4 , wherein:
the coil is provided between the two protruding portions inside the first yoke; and
when the movable element is at the neutral position, the magnet portion and the coil are located at a substantially same position in the axial direction.

6. The servo valve according to claim 3 , wherein:
the first yoke is connected to the tubular body so as to cover the magnet portion within a moving range within which the magnet portion is moved in the axial direction by sliding of the movable element.

7. The servo valve according to claim 3 , wherein:
the first yoke comprises two yokes arranged so as to interpose the coil between the two yokes in the axial direction.

8. The servo valve according to claim 3 , wherein the magnet portion comprises:
two permanent magnets arranged in the axial direction and magnetized in the axial direction; and
a second yoke interposed between the two permanent magnets.

9. The servo valve according to claim 8 , wherein:
the two permanent magnets are magnetized in mutually different directions.

10. The servo valve according to claim 3 , wherein:
a sleeve provided with openings communicating with the respective ports is disposed inside the tubular body;
the movable element includes the magnet portion, a spool disposed inside the sleeve in the axial direction, a shaft connecting the magnet portion and the spool in the axial direction, and an annular first fixed portion disposed on the shaft on a magnet portion side and to which one end of the first elastic portion is fixed;
an annular second fixed portion is provided inside the tubular body and on a first yoke side, the annular second fixed portion being fixed to the tubular body and the first yoke, wherein the shaft and the first fixed portion penetrate through the annular second fixed portion, and one end of the second elastic portion is fixed to the annular second fixed portion;
the connecting portion is an annular member configured to, inside the tubular body, abut against the spool and a portion of the tubular body that is located on a spool side, the shaft penetrating through the connecting portion;
the first elastic portion is interposed between the connecting portion and the first fixed portion inside the tubular body; and
the second elastic portion is interposed between the connecting portion and the annular second fixed portion inside the tubular body.

11. The servo valve according to claim 3 , further comprising:
a sensor disposed adjacent to the magnet portion in the axial direction and configured to detect magnetic flux.

12. The servo valve according to claim 2 , wherein:
the drive unit includes a yoke, which serves as the tubular body, connected to the tubular body in the axial direction, two permanent magnets provided respectively at opposite ends of the yoke in the axial direction, an iron core provided inside the yoke so as to face the yoke, and a coil wound around the iron core;
the movable portion comprises the iron core and the coil; and
the movable element is slid in the axial direction by a magnetic attractive force including at least one of a force acting between the two permanent magnets and the iron core, and a force exerted on the movable portion due to energization to the coil.

13. The servo valve according to claim 2 , wherein:
the drive unit includes a yoke, which serves as the tubular body, connected to the tubular body in the axial direction, a permanent magnet provided at a central portion of the yoke in the axial direction, a coil provided inside the yoke in the axial direction so as to face the permanent magnet, and an iron core, which serves as the movable portion, provided inside the yoke in the axial direction; and
the movable element is slid in the axial direction by a magnetic attractive force including at least one of a force acting between opposite ends of the yoke and the iron core, and a force exerted on the iron core due to energization to the coil.

14. The servo valve according to claim 1 , wherein:
the first elastic portion and the second elastic portion are spring members.

15. The servo valve according to claim 1 , wherein:
a restoring force to return the movable element to the neutral position is adjusted by balancing a force exerted on the movable element from the drive unit with the first elastic force or the second elastic force.

Assignees

• Smc Corp

Inventors

• Sakashita Junji
• Inoue Kaname
• Yajima Hisashi
• Ishikawa Masayuki
• Ito Satoru

Classifications

• H01F7/1615

  Armatures or stationary parts of magnetic circuit having permanent magnet · CPC title

• F16K31/082

  using a electromagnet and a permanent magnet · CPC title

• F16K11/07 Primary

  with cylindrical slides · CPC title

• F16K37/0033 Primary

  using a permanent magnet, e.g. in combination with a reed relays · CPC title

• Y10T137/8667

  Reciprocating valve · CPC title