JP2800873B2 - Hydraulic servo valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic servo valve in which both ends of a spool housed in a sleeve are supported in a non-contact manner by static pressure bearings, and more particularly to a hydraulic servo valve using water as a working fluid.

[0002]

2. Description of the Related Art A hydraulic servo valve using water as a working fluid and solving the problem relating to oil has been disclosed by the present applicant in Japanese Patent Application Laid-Open No. 1-11 / 1999.
These are proposed in JP-A-2004-2004, JP-A-1-112005, JP-A-1-145404, and JP-A-1-14505.

An example will be described with reference to FIG.

In FIG. 4, a sleeve 2A is formed on a valve body 1A made of a non-rust material such as a plastic material. In the sleeve 2A, a spool 11A made of a non-rust material such as a plastic material has a pair of hydrostatic bearings 1 at both ends.
5a and 15b support the sleeve 2A in a non-contact manner, and are centered by springs 4 interposed in left and right spring chambers 3a and 3b. And the hydrostatic bearing 15a,
As shown in FIG. 5, four pockets 16 each having a diagonal stop 17 are formed in 15b.

The pipes 6a, 6b connected to the spring chambers 3a, 3b project into a central chamber 8 formed in the valve body 1A.
7b is formed. A gap D is formed between the nozzles 7a and 7b, and the flapper 10 of the torque motor 9 fixed to the valve body 1A is provided in the gap D.
a and 7b are inserted with a slight gap.

[0006] With such a configuration, the pressurized water PS enters the sleeve 2A from the pump port P and passes through the two passages A1 and A2.
The spool 11A is branched into a path and spouts out of the four throttle portions 17 of the hydrostatic bearings 15a and 15b into the pocket 16 to float the spool 11A and support it in a non-contact manner with the sleeve 2A.

Since the hole diameter of the narrowed portion 17 of the pocket 16 is small, foreign matter mixed in water tends to be clogged, and if one narrowed portion 17 is clogged, the bearing effect will be impaired. Further, since high-pressure and high-speed water passes through the pocket 16, the iris 17 is worn out by cavitation and the diameter of the iris is changed, which may lead to a decrease in the bearing effect.
Japanese Patent Application Laid-Open No. Hei 4-191506 discloses a hydraulic servo valve in which an orifice and a pocket are provided in a spool and self-aligning action by a hydrostatic bearing is used.
However, since the known technique also uses an orifice, clogging occurs when foreign matter is mixed in the working fluid. The hydrostatic bearing itself is known, and is disclosed, for example, in Japanese Patent Publication No. 36-15107. However, such known techniques do not hold the spool.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hydraulic servo valve having a hydrostatic bearing which does not cause clogging even if water containing foreign matter is used.

[0009]

According to the present invention, a spool (1) is provided in a sleeve (2) formed in a valve body (1).
1) is supported at both ends thereof by a hydrostatic bearing (B1, B2) in a non-contact manner with respect to a sleeve (2), and a hydraulic pressure centered by a spring (4) provided in spring chambers (3a, 3b) at both ends. In the servo valve, the static pressure bearing (B
1, B2) includes a groove (5) formed in the valve body (1), and a plurality of outlets (C) diagonally opened toward the groove (5). A small diameter portion (12) is formed on the opposed spool (11), and tapered lands (1) are formed on both sides of the small diameter portion (12).
3) is formed.

[0010]

[Explanation of the function and effect] Therefore, the pressurized water jetted from the jet port flows from the groove along the tapered lands on both sides.
At that time, since the pressure at the small diameter portion is larger than the pressure between the spool and the sleeve at the land portion of the spool, the pressurized water presses the tapered land. The spool floats from the sleeve by the radially inward component force of the pressing, and the self-centering action is performed. As described above, according to the present invention, since the self-alignment is performed by the thrust generated in the taper land, the water pressure can be balanced, and wear due to cavitation can be prevented. In addition, since the squeezing section is not required, the problem of clogging of foreign matter contained in the pressurized water is eliminated.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, portions corresponding to those in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted.

1 and 2, the hydrostatic bearings B1, B
Reference numeral 2 denotes a groove 5 formed in the valve body 1, a plurality of (four in the illustrated example) ejection ports C opened diagonally toward the groove 5, and a spool 11 facing the ejection port C.
A pair of tapered lands 1 formed on both sides of the small-diameter portion 12 of FIG.
And 3. And the diameter of the spout C is
As compared with the conventional throttle portion 17 (FIG. 5), it is formed so large that foreign matter mixed in water does not clog.

In operation, as shown in FIG. 3, the pressurized water PS is supplied from the outlet C through the groove 5 to the small-diameter portion 1 of the spool 11.
2 and flows toward the taper land 13 side. At this time, the pressure P between the spool 11 and the sleeve 2
1 is sufficiently smaller than the pressure P2 on the small diameter portion 12 side. Therefore, the pressure water PS presses the taper land 13 by the differential pressure (P2-P1). A thrust T is generated on the spool 11 by the radially inward component of the pressing force, and the thrust is lifted from the inner surface of the sleeve 2 to support the spool 11 in a non-contact manner and perform an automatic centering action.

[0015]

As described above, according to the present invention, the following excellent effects can be obtained. (1) Since the spool is floated by the water pressure flowing through the taper land, the self-centering action is suitably performed. (2) The restriction portion unlike the prior art is not required, and clogging does not occur even if water containing foreign matter is used as a working fluid. (3) Water pressure can be dispersed over the entire taper land, and there is no wear due to cavitation. (4) Stable automatic alignment is performed as compared with the conventional example.

[0016]

[Brief description of the drawings]

FIG. 1 is a side sectional view showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a sectional side view for explaining the operation.

FIG. 4 is a side sectional view illustrating a conventional hydraulic servo valve.

5 is a view taken in the direction of arrows BB in FIG. 4;

[Explanation of symbols]

 A1, A2: passage B1, B2: static pressure bearing C: jet port P: pump port PS: pressurized water 1, 1A: valve body 2, 2A: sleeve 3a 3b Spring chamber 4 Spring 5 Groove 6a, 6b Pipe line 7a, 7b Nozzle 8 Central chamber 9 Torque motor 10 Flapper 11 , 11A: spool 12: small diameter portion 13: taper land 15a, 16a: hydrostatic bearing 16: pocket 17: throttle portion

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masao Shinda 4-2-1 Motofujisawa, Fujisawa City, Kanagawa Prefecture Inside Ebara Research Institute, Inc. (72) Inventor Shinpei Miyagawa 4-2-1 Motofujisawa, Fujisawa City, Kanagawa Prefecture No. Ebara Research Institute, Inc. (56) References JP-A-4-191506 (JP, A) JP-A-1-112005 (JP, A) JP-A-1-145405 (JP, A) JP-A-1- 112004 (JP, A) JP-A-1-145404 (JP, A) JP-A 62-93404 (JP, U) Patent 173386 (JP, B1) JP-B 36-15107 (JP, B1) JP-B 57 -20933 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F15B 13/043

Claims (1)

(57) [Claims] 1. A sleeve (2) formed on a valve body (1).
A spool (11) has a hydrostatic bearing (B1, B2) at both ends.
B2) in a non-contact manner with respect to the sleeve (2) and in a hydraulic servo valve centered by springs (4) provided in spring chambers (3a, 3b) at both ends, the hydrostatic bearings (B1, B2). ) Is provided with a groove (5) formed in the valve body (1) and a plurality of ejection ports (C) opened diagonally toward the groove (5), and a spool facing the ejection port (C). (11) has a small diameter part (1
2), and a tapered land (13) is formed on both sides of the small diameter portion (12).