JPH06307408A - Hydraulic servo valve - Google Patents

Abstract

PURPOSE:To constantly obtain an optimum nozzle flapper characteristic by making a passage guided to a nozzle flapper composed of two flows, namely, a flow from a static pressure bearing and a flow through an inlet orifice. CONSTITUTION:Passages 12a, 12b, which are connected to a body 1 and bifurcating to static pressure bearings 15a, 15b, are communicated to lines 6a, 6b through inlet orifices 13a, 13b, respectively. Pressure water PC from a pump port P flow bifurcatingly to two passages of passages 12a, 12b, namely, flows B1, B2 to static pressure bearings 15a, 15b and flows C1, C2 to lines 6a, 6b passing through the inlet orifices 13a, 13b. Flows B1, B2 flow into lines 6a, 6b as keeping a spool 11 and a sleeve 2 in an untouched condition by static pressure bearing effect. Flows C1, C2 past through orifices 13a, 13b join flows B1, B2 entered into lines 6a, 6b and are guided to the flapper part.

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 having a sleeve and a spool built therein, which constitutes a fluid switching port and whose working fluid is water.

[0002]

2. Description of the Related Art Various hydraulic servo valves are known, for example, the one shown in FIG. 2 is known.

In FIG. 2, a sleeve 2 is formed on a valve body 1A made of a non-rust material such as a plastic material. Inside the sleeve 2, a spool 11 made of a non-rust material such as a plastic material has a pair of static pressure bearings 15 at both ends.
a and 15b are supported on the sleeve 2 in a non-contact manner,
Centering is performed by springs 4 interposed in the left and right spring chambers 3a and 3b.

Further, the conduits 6a, 6b connected to the spring chambers 3a, 3b are projected into the central chamber 8 formed in the valve body 1A, and the nozzles 7a, 7 are respectively provided at their projecting ends.
b 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.
The nozzles 7a and 7b and the flapper 10 form a nozzle / flapper section NF.

With such a construction, the pressurized water PS enters the sleeve 2 from the pump port P, is branched into two passages A1 and A2, and is illustrated from four throttle portions (not shown) of the static pressure bearings 15a and 15b. Do not gush into the pocket, spool 1
1 is floated and supported in a non-contact manner with respect to the sleeve 2. Reference numeral 16 in the figure is a load which is switched and controlled by a hydraulic servo valve.

As described above, the hydraulic servo valve has the static pressure bearing 15
A and 15b are used to support the spool 11 and the sleeve 2 in a non-contact manner. Therefore, as compared with the conventional hydraulic servo valve, the gap h between the spool 11 and the sleeve 2 is large, so that the internal leakage L (a part of the pressurized liquid directly returns without working (see FIG. 3). ) Has a big drawback.

To reduce this, the method of reducing the gap h between the spool and the sleeve is the simplest and most effective.
However, the conventional hydraulic servo valve has the static pressure bearing 15
It is characterized in that the fluid that has passed through a and 15b is guided to the nozzle / flapper section NF and is used for back pressure control for driving the spool 11. When the gap h is reduced to reduce internal leakage, the nozzle / flapper section NF is reduced. The flow rate of the fluid guided to the NF decreases, and the characteristics of the nozzle / flapper section NF change significantly (see FIGS. 4 and 5). That is, when the gap h between the spool and the sleeve is reduced by using the same nozzle diameter, the gradient of the nozzle back pressure Pn with respect to the distance Xn increases, and the nozzle back pressure Pn greatly changes with a slight flapper displacement. If this gradient is large, the nozzle flapper part N
Although the responsiveness of F is improved, the stability is deteriorated, which may cause the servo valve to vibrate. In FIG. 4, dn: nozzle diameter of nozzles 7a, 7b Xn: nozzle-flapper distance between nozzles 7a, 7b and flapper Pn: nozzle back pressure of nozzles 7a, 7b Qn: from nozzles 7a, 7b Is the flow rate of.

In order to obtain the hydrostatic bearing effect, it is necessary to maintain the nozzle back pressure (Pno) at the flapper neutral position high to some extent. At this time, the nozzle-flapper distance Xno becomes extremely small (several tens of μm). ), A high manufacturing accuracy is required for the nozzle / flapper section NF, which causes a problem that the manufacturing is difficult. If the gap h is reduced,
In principle, if the nozzle diameter dn is changed accordingly, the gap h
It is possible to obtain the same nozzle flapper characteristics regardless of the above, but in that case, the nozzle diameter dn becomes considerably small,
After all, there are problems in production and contamination.

[0009]

The present invention has been made in order to eliminate these drawbacks. In addition to the conventional hydrostatic bearing portion, another orifice is provided so that the fluid passing through both of them can be provided. It is an object of the present invention to provide a hydraulic servo valve that can always obtain optimum nozzle flapper characteristics by being guided to a nozzle flapper section and utilized.

[0010]

According to the present invention, in a hydraulic servo valve having a sleeve and a spool, and the working fluid is water, the flow passing through static pressure bearings provided at both ends of the spool is controlled by a nozzle flapper. A passage communicating with the nozzle / flapper portion from the pump port through the throttle is provided so that both flows can be used together.

It is preferable that the throttle is composed of a passage for guiding the pump port to the static pressure bearing and an orifice provided in a communicating portion for communicating with a passage for guiding the flow passing through the static pressure bearing to the nozzle / flapper portion.

[0012]

In the hydraulic servo valve constructed as described above, the flow of water passing through the hydrostatic bearing and the water from the pump port before flowing into the hydrostatic bearing are combined after passing through the throttle to the nozzle / flapper section. Be guided. Therefore, even if the gap between the spool and the sleeve is reduced, the optimum nozzle flapper characteristic can be obtained.

[0013]

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

In FIG. 1, parts corresponding to those in FIG. 2 are designated by the same reference numerals, and duplicate description will be omitted.

In FIG. 1, passages 12a and 12b connected to the main body 1 and branched to reach the hydrostatic bearings 15a and 15b.
Are communicated with the pipelines 6a and 6b via inlet orifices 13a and 13b, which are throttles, respectively.

Next, the operation will be described.

The pressurized water PS passes from the pump port P to the passage 12
The hydrostatic bearings 15a, 1
Flows B1 and B2 to 5b and inlet orifice 13
Flows C1 and C passing through a and 13b to the pipelines 6a and 6b
It is branched to 2. The flows B1 and B2 hold the spool 11 and the sleeve 2 in a non-contact state by the hydrostatic bearing effect, and flow into the pipe lines 6a and 6b. The inlet orifices 13a, 1 are connected to the flows B1, B2 entering the pipes 6a, 6b.
The flows C1 and C2 that have passed through 3b join and are guided to the nozzle / flapper unit NF.

Therefore, the clearance h between the spool and the sleeve h
Of the hydrostatic bearing 15a,
Even if the amount of water introduced to the nozzle / flapper section NF via 15b is small, the flow rate to the nozzle / flapper section NF is maintained at an appropriate amount by changing the diameters of the inlet orifices 13a and 13b, and the optimum nozzle / flapper section is always provided. The characteristics can be obtained.

[0019]

According to the present invention, the hydraulic servo valve has a structure in which the flow path guided to the nozzle / flapper section is composed of the flow from the static pressure bearing section and the flow through the inlet orifice. While the self-aligning action by the static pressure bearing, which is a feature of the above, is provided, the characteristics of the nozzle flapper can be changed arbitrarily even if the radial gap between the spool and the sleeve is reduced to reduce the internal leakage flow. This has the effect of optimally adjusting the performance of the hydraulic servo valve.

[Brief description of drawings]

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

FIG. 2 is a side sectional view showing an example of a conventional hydraulic servo valve.

FIG. 3 is a diagram illustrating a leak of FIG.

FIG. 4 is a drawing showing details of a nozzle flapper section.

FIG. 5 is a drawing for explaining the influence of the gap between the spool and the sleeve on the nozzle-flapper distance-nozzle back pressure gradient.

[Explanation of symbols]

 A1, A2 ... Passages B1, B2 ... Flow to static pressure bearing C1, C2 ... Flow to pipeline NF ... Nozzle and flapper P ... Pump port PS ... Compressed water 1, 1A ... Main body 2 ... Sleeve 3a, 3b ... Spring chamber 4 ... Spring 6a, 6b ... Pipe line 7a, 7b ... Nozzle 8 ... Central chamber 9 ... Torque motor 10 ... Flapper 11 ... Spool 12a, 12b ... Passage 13a, 13b ... Inlet orifice 15a, 15b ... Hydrostatic bearing 16 ... Load

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masao Shinoda 4-2-1 Honfujisawa, Fujisawa-shi, Kanagawa Prefecture EBARA Research Institute Ltd. (72) Shinpei Miyakawa 4-2-1, Fujisawa, Kanagawa Prefecture No. 1 Ebara Research Institute, Inc. (72) Inventor Akemi Urata 2-18-18 Ogawa, Machida, Tokyo

Claims (1)

[Claims] 1. In a hydraulic servo valve having a sleeve and a spool, the working fluid being water, the flow passing through static pressure bearings provided at both ends of the spool is guided to a nozzle flapper portion, and a throttle is provided from a pump port. A hydraulic servo valve characterized in that a passage communicating with the nozzle flapper is provided, and both flows are used together.