Air servo valve
AssigneeSMC Corporation
InventorsHisashi Yajima, Nobuhiro Fujiwara, Daisuke Matsumoto, Seikai Yo, Hiroshi Miyachi
Life of this patent
Estimating the term…
Abstract
An exciting coil is wound on a cylindrical yoke provided with a pair of pole teeth, a cylindrical permanent magnet where N pole and S pole are magnetized in a radial direction is disposed so as to be movable in a hollow portion of the yoke and the permanent magnet is coupled to a spool by a magnet holder, and a displacement sensor is disposed in a hollow portion of the permanent magnet so as to be positioned on a center axial line of the permanent magnet, so that the displacement of the permanent magnet is detected by the displacement sensor and the degree of opening of the spool is controlled by performing feedback of the displacement to a control portion.
Claims20
An air servo valve, comprising:
- a valve switching portion having a plurality of ports, a valve hole communicating with the ports, and a spool which is slidably inserted in the valve hole to switch flow paths among the ports;
- a driving portion having a cylindrical yoke provided with a pair of pole teeth opposed to each other, at least one exciting coil wound on the yoke, a cylindrical permanent magnet which is disposed in a hollow portion of the yoke movably in an axial direction of the yoke and where N pole and S pole are magnetized in a radial direction, and a magnet holder made of non-magnetic body, which couples the permanent magnet and the spool to each other;
- a displacement sensor which is disposed so as to position on a center axial line of the magnet inside the permanent magnet and detects the displacement of the permanent magnet from change of flux density;
- and
- a control portion which compares a detection signal from the displacement sensor with a set value to adjust a degree of valve opening by controlling the driving section on the basis of the deviation of the detection signal from the set value.
An air servo valve, comprising:
- a valve switching portion having a plurality of ports, a valve hole communicating with the ports, and a spool which is slidably inserted in the valve hole to switch flow paths among the ports;
- a driving portion for driving the spool, which comprises members listed below, namely, including a yoke comprising a cylindrical outer cylinder portion and a pair of inner cylinder portions, the inner cylinder portions being positioned in the interior of the outer cylinder portion so as to be opposed to each other via a constant gap concentrically with the outer cylinder portion and the yoke being formed with a first pole tooth and a second pole tooth, at least one exciting coil received in a space portion between the outer cylinder portion and the inner cylinder portions of the yoke, a cylindrical magnet holder made of non-magnetic body, which is received in a hollow portion surrounded by the first pole tooth and the second pole tooth of the yoke so as to be capable of displacing in an axial line direction of the yoke and which is coupled to the spool, and a cylindrical permanent magnet which is fitted on an outer periphery of the magnet holder so as to be opposed to the first pole tooth and the second pole tooth, where N pole and S pole are magnetized in a radial direction, and which has an axial length substantially spanning the pair of pole teeth;
- a displacement sensor which is disposed in a hollow portion of the magnet holder so as to be positioned on a center axial line of the permanent magnet and which detects the displacement of the permanent magnet from change of flux density;
- and
- a control portion which compares a detection signal from the displacement sensor with a set value to control the driving portion on the basis of the deviation therebetween, thereby adjusting the degree of valve opening.
Dependencies are inferred from the claim text.