DIRECT OPERATED HYDRAULIC SERVO VALVES

Abstract

The servovalve incorporates a rotating plate valving element which connects between the valve ports through cavities formed inside it. The valving element cavities are formed symmetrically in both the valving elements sides, where each pair of symmetrical cavities is optionally separated by a stiffening web. Holes through the webs connect between the symmetrical cavities. The control orifices are formed between some edges in the valving element cavities and edges of cavities in adjacent fixed elements surrounding the valving element and properly designed for this purpose. The flow ducts inside the valves are formed by the cavities in the valving element and the adjacent parts to provide enough flowing cross sectional areas. The control orifices are formed in pairs at both valving element sides to duplicate the area and provide symmetry for flow forces lateral components balance. Each portion of the valving elements is subjected to the same pressure at its both sides to provide static balance. The rotational movement generates relatively large control orifice from rotary or linear drivers of short strokes. Thin valving elements with cavities provide lowest inertia for high speed of response.

Claims

1. Directional control and servo valve incorporates a thin plate valving element of limited inertia which is fed with limited angular displacement proportional to the required control value. The plate valving element two sides are subjected to almost same pressure at each portion of it in order to be almost statically balanced in its axial direction. Control edges that form control orifices are symmetrical at valving element both sides to divide the liquid flow in almost symmetrical pattern. The liquid passes between the valving element both sides through holes inside it.

2. Directional control and servo valve as in item 1 in which the valve ports lead to cavities in the valve housing, or in another intermediate part inside the housing, where cavities and edges are symmetrically distributed around both valving element sides.

3. Directional control and servo valve as in item 1 and 2, in which the plate valving element has cavities corresponding to the cavities mentioned in item 2.

4. Directional control and servo valve as in item 1 to 3 in which control orifices are formed between the edges of the plate valving element and the edges on its vicinity parts at its both sides due to the angular displacement fed to the valving element, the control orifice area is proportional to the value of the feeding angle.

5. Directional control and servo valve as in items from 4 in which the control orifices formed between the plate valving element cavities' edges and the corresponding cavities' edges of its vicinity parts are symmetrically distributed on both valving element sides

6. Directional control and servo valve as in items from 1 to 5 in which the cavities in the valving element produce the same pressure as on both sides of each part.

7. Directional control and servo valve as in items from 1 to 6 in which webs are used to increase the valving element rigidity.

8. Webs in item 6 have through holes to allow liquid flow between the valving element sides.

9. Directional control and servo valve as in items from 1 to 8 in which the valving element is angularly displaced using linearly or angularly displaced actuators.

10. Directional control and servo valve as in items from 1 to 9 in which the valving element is centered using a spring or set of springs

11. Directional control and servo valve as in items from 1 to 10 in which cavities can be formed to collect leakage liquid and pass it to a tank

12. Directional control and servo valve as in items from 1 to 11 in which seals can be used.

13. Directional control and servo valve as in items from 1 to 12 in which different connection pattern between the valve ports can be realized at the valve different working positions.

14. Directional control and servo valve as in items from 1 to 13 that can be complemented by performance enhancement accessories such as seals, measuring or monitoring tools can be added without considering them a modification in its idea.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 Shows a section in the valve housing and its cavities and ports to be connected to the external lines.

[0022] FIG. 2 Shows the valving element with its cavities, ports, and webs.

[0023] FIG. 3 Shows the valving element assembled in the housing, and the edges that form the control orifices.

[0024] FIG. 4 Shows a section in the valve main parts with the ports and cavities.

[0025] FIG. 5 Shows another section in the valve main parts with the ports and cavities.

[0026] FIG. 6 Shows a third section in the valve main parts with the ports and cavities.

[0027] FIG. 7 Shows the valve housing and the valving element after being displaced angularly to open controls orifices.

[0028] FIG. 8 Shows a section in an open valve and the liquid flow paths in the cavities and the different openings.

[0029] FIG. 9 Shows a section in an open valve and the other liquid flow paths in the cavities and the different openings.

INDUSTRIAL APPLICABILITY

[0030] These valves are directional control valves that can replace the currently widely used directional control valves, but with higher speed of response which suits the applications demanding fast switching, they suit also applications in which digital control techniques are to be used. From this side, these valves can be viewed as servo valves. Furthermore, the valving element of a valve of this type can assume any position between its central and extreme position, and thus it can replace servo valves of the same size with a flow rate capacity higher than the servo valve. This would lead to replace a two-stage servo valve by a single stage valve of the presented type. Using a valve of the proposed type as a pilot valve would increase the speed of response of the pilot operated valve main stage. If used as a pilot valve for a conventional directional control valve, the whole valve would be a fast switching to be used in fast response control techniques, with relatively much lower cost.