Valve, in particular pilot-operated proportional directional poppet valve

Abstract

A valve, in particular a pilot-operated proportional directional poppet valve, has a valve housing (7) with a fluid inlet (21) and a fluid outlet (23). The fluid stream between the fluid inlet (21) and the fluid outlet (23) is adjustable by a main piston (27). A pilot valve chamber (37) on a rear face (29) of the main piston (27) has a pilot valve closing member (33) movable by an actuating device (69) to adjust the fluid stream between the pilot valve chamber (37) and the fluid outlet (23). A supply aperture (3) is between the fluid inlet (21) and the pilot valve chamber (37). The opening cross-section of the supply aperture (3) can be reduced by a control element (49).

Claims

1. A valve, comprising: a valve housing having a fluid inlet and a fluid outlet; a main piston movable in said housing and adjusting a main fluid stream between said fluid inlet and said fluid outlet; a pilot valve chamber on a rear face of said main piston; a pilot valve closing member movable by an actuator and adjusting a pilot fluid stream between said pilot chamber and said fluid outlet; and a supply aperture located between said fluid inlet and pilot chamber, an opening cross section of said supply aperture being reduceable by a control element assigned to said valve closing member.

2. A valve according to claim 1 wherein said control element comprises a radial projection on said pilot valve closing member.

3. A valve according to claim 2 wherein said radial projection comprises a collar on said pilot valve closing member, said collar having at least one pressure-relief bore.

4. A valve according to claim 1 wherein said supply aperture comprises a plurality of aperture bores, an opening cross section of at least one of said aperture bores being reduceable by control element.

5. A valve according to claim 4 wherein each of said aperture bores have a same diameter.

6. A valve according to claim 4 wherein said aperture bores are in said main piston and are offset relative to one another at least one of axially or over a circumference of said main piston.

7. A valve according to claim 1 wherein an aperture slot is between said fluid inlet and said supply aperture.

8. A valve according to claim 7 wherein said aperture slot comprises an annular gap between said valve housing and said main piston.

9. A valve according to claim 1 wherein a maximum volume controller is in said main piston in an outflow between said pilot valve chamber and said fluid inlet.

10. A valve according to claim 9 wherein said maximum volumetric flow controller comprises a control piston acted on a front face thereof by pressure of fluid flowing out of said pilot valve chamber and acted on a rear face thereof by a spring.

11. A valve according to claim 10 wherein said control piston comprises a fluid channel therein; and control edges of said maximum volumetric flow controller are in said control piston and in said main piston as bores therein, opening cross sections limited by said control edges being dependent on positions of said control piston.

12. A valve according to claim 11 wherein said fluid channel comprises a lateral inlet opening in said control piston.

13. A valve according to claim 11 wherein said control piston is in an axial bore in said main piston.

14. A valve according to claim 13 wherein said control piston is held in said axial bore by an end cap.

15. A valve according to claim 1 wherein said main piston is biased toward a closing position by a spring via said pilot valve closing member.

16. A valve according to claim 1 wherein said pilot valve closing member is drawable away from a pilot valve seat by said actuator.

17. A valve, comprising: a valve housing having a fluid inlet and a fluid outlet; a main piston movable in said housing and adjusting a main fluid stream between said fluid inlet and said fluid outlet; a pilot valve chamber on a rear face of said main piston; a pilot valve closing member movable by an actuator and adjusting a pilot fluid stream between said pilot chamber and said fluid outlet; and a supply aperture located between said fluid inlet and pilot chamber, an opening cross section of said supply aperture being reduceable by a control element, said supply aperture including a plurality of aperture bores, an opening cross section of at least one of said aperture bores being reduceable by a control element.

18. A valve according to claim 17 wherein each of said aperture bores have a same diameter.

19. A valve according to claim 17 wherein said aperture bores are in said main piston and are offset relative to one another at least one of axially or over a circumference of said main piston.

20. A valve, comprising: a valve housing having a fluid inlet and a fluid outlet; a main piston movable in said housing and adjusting a main fluid stream between said fluid inlet and said fluid outlet; a pilot valve chamber on a rear face of said main piston; a pilot valve closing member movable by an actuator and adjusting a pilot fluid stream between said pilot chamber and said fluid outlet; a supply aperture located between said fluid inlet and pilot chamber, an opening cross section of said supply aperture being reduceable by a control element; and a maximum volume controller in said main piston in an outflow between said pilot valve chamber and said fluid inlet, said maximum volumetric flow controller including a control piston acted on a front face thereof by pressure of fluid flowing out of said pilot valve chamber and acted on a rear face thereof by a spring.

21. A valve according to claim 20 wherein said control piston comprises a fluid channel therein; and control edges of said maximum volumetric flow controller are in said control piston and in said main piston as bores therein, opening cross sections limited by said control edges being dependent on positions of said control piston.

22. A valve according to claim 21 wherein said fluid channel comprises a lateral inlet opening in said control piston.

23. A valve according to claim 20 wherein said control piston is in an axial bore in said main piston.

24. A valve according to claim 23 wherein said control piston is held in said axial bore by an end cap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Referring to the drawings that form a part of this disclosure.

(2) FIG. 1, is a side view in section of a valve according to an exemplary embodiment of the invention, with the valve shown in the closed neutral position;

(3) FIG. 2 is a side view in section of the valve of FIG. 1 in a working position with a low prevailing load pressure;

(4) FIG. 3 is a side view in section of the valve of FIG. 1 in a working position with a high prevailing load pressure, in which the opening stroke of the main piston is adjusted, i.e., reduced; and

(5) FIG. 4 is a side view in section of the main piston of the valve of FIG. 1 in the region of the fluid inlet.

DETAILED DESCRIPTION OF THE INVENTION

(6) In FIGS. 1 to 3, the valve 1 is designed as a pilot-operated proportional directional valve having a cartridge design. The design is based on a conventional proportional directional poppet valve, into which a reducible supply aperture 3 and a maximum volumetric flow controller 5 have been integrated.

(7) The valve 1 can be inserted into a valve block, which is not depicted in greater detail. To this end, the valve housing 7 is designed so as to taper in steps on the circumferential side 9. The individual steps are designed as a hexagonal step 11, a threaded step 13, and a simple step 15, and are sealed by circumferential annular seals 17, 19. The valve housing 7 comprises a lateral fluid inlet 21 and a fluid outlet 23 at the base. A main piston 27 is inserted into an axial bore 25 of the valve housing 7. The fluid stream between the fluid inlet 21 and the fluid outlet 23 can be regulated by the main piston 27.

(8) A pilot valve 31 is provided on a rear face 29 of the main piston 27. The pilot valve 31 comprises a pilot valve closing member 33, which interacts with a pilot valve seat 35 in the main piston 27.

(9) The supply aperture 3 is provided in the main piston 27 to limit the supply of pilot fluid to the pilot valve chamber 37. The supply aperture 3 comprises a plurality of aperture bores 39, 41. Each aperture bore 39, 41 comprises two sections 43, 45. In one radially outer section 43, the diameter of the aperture bores 39, 41 is larger than in a radially inner section 45. The aperture bores 39, 41 are disposed in the main piston 27 so as to be offset axially and over the circumference. All aperture bores 39, 41 are uniformly supplied with pilot fluid via a circumferential groove 47 of the main piston 27. To reduce the opening cross-section of the supply aperture 3, a control element 49 in the form of a collar is provided on the pilot valve closing member 33. By pilot valve closing member 33, the aperture bores 39, 41 can be reduced or closed entirely depending on the axial position of the pilot valve closing member 33 relative to the main piston 27. The further the pilot valve closing member 33 is drawn out of the main piston 27, the greater the extent to which the opening cross-section of the supply aperture 3 is reduced. The collar 49 comprises pressure-relief bores 51 which are distributed over the circumference. By this design, the control behavior of the pilot valve closing member 33 is not noticeably changed by the collar 49. The supply aperture 3 can be provided in the proximity of, or at a relatively great axial distance from, the pilot valve seat 35. If the supply aperture 3 is disposed sufficiently close to the pilot valve seat 35, the adjustment regions of the pilot valve 31 and the control of the opening cross-section of the supply aperture 3 overlap. Given a sufficiently large separation, the pilot valve closing member 33 must initially move so far away from the pilot valve seat 35 that the pilot valve seat 35 is completely opened before the opening cross-section of the supply aperture 3 is reduced.

(10) In addition, an aperture slot 53 is assigned to the supply aperture 3. The aperture slot 53 is located between the fluid inlet 21 and the supply aperture 3 and is formed by an annular gap 55 between the main piston 27 and the valve housing 7. The aperture slot 53 has a filtration function. It is intended to prevent relatively large particles in the fluid from entering and obstructing the pilot valve 31. This entry of particles would invariably result in a failure of the valve 1.

(11) The pilot valve closing member 33 has a pointed cone 57 and cooperates with the pilot valve seat 35, which is matched thereto, at one end 59 of an axial bore 61 of the main piston 27. The pilot valve closing member 33 is acted upon by a stiff spring 63, which is supported on the pilot valve closing member 33 via a disk 65 and a snap ring 67. When an actuating device 69 is inactive, the valve 1 is therefore preloaded into the blocking position (FIG. 1).

(12) The actuating device 69 is designed as a pulling actuating device 69 to draw the pilot valve closing member 33 away from the pilot valve seat 35 when current flows through said actuating device.

(13) The maximum volumetric flow controller 5 is located in the main piston 27 downstream of the pilot valve seat 35. The maximum volumetric flow controller 5 is disposed in an outflow 71 between the pilot chamber 37 and the fluid outlet 23. The maximum volumetric flow controller 5 comprises a control piston 73, which is acted upon on the front face 75 by the pilot fluid stream and is acted upon in the opposite direction on the rear face 77 by a spring 79. The control piston 73 comprises a fluid channel 81 having a lateral inlet opening 83 that functions as a metering aperture. The pilot fluid can therefore enter the control piston 73 and flow into the fluid outlet 23 through radial bores 85, 87 in the control piston 73 and in the main piston 27. These bores form a control aperture. The metering aperture has a flow-control function. Depending on the opening position of the control aperture formed by the bores 85, 87, the rear face 77 of the control piston 73 is acted upon by pressure that is reduced by the control aperture. The bores 85, 87 in the control piston 73 and the main piston 27 thereby form control edges of the maximum volumetric flow controller 5, which limit the opening cross-section depending on the position of the control piston 73. The spring 79 is positioned between a recess 89 of the control piston 73 and a recess 91 of an end cap 93, which end cap is fastened in the main piston 27. To keep the design as simple as possible, the control piston 73 is inserted into the axial bore 61 of the main piston 27. The end cap 93 is screwed into an internal thread 95 of the axial bore 61 or is held in a clamped manner in the axial bore 61.

(14) In addition, an adjustable maximum limitation of the opening stroke of the main piston 27 is provided. By a mechanically adjustable maximum stroke limitation on the actuating device 69, the maximum volumetric flow of the valve 1 can be mechanically adjusted independently of the magnetic force of the actuating device 69.

(15) A portion of the main piston 27 in the region of the fluid inlet 21 is shown in FIG. 4. The main piston 27 is provided with a circumferential constriction 99 directly adjacent to a conical main valve surface 97 in the direction of the fluid outlet 23. That constriction 99 has a V-shaped design.

(16) A valve 1 therefore has an opening stroke that is dependent on the actuating device 69 and on the load pressure prevailing at the fluid inlet 21. The effect of a high load pressure is that the opening stroke is reduced. If the load pressure is too low, the opening stroke can be increased by enlarging the supply aperture 3. The requirements for a leakage-free valve 1, which ensures a uniform volumetric flow even in the presence of a low pressure differential and which is independent of the prevailing load pressure, are therefore met.

(17) Due to the integration of the volumetric flow control, the solution according to the invention also requires less installation space than the known solutions, in which a maximum volumetric flow controller or a pressure regulator is disposed downstream of conventional proportional directional poppet valve. Finally, this valve can also be produced at lower cost.

(18) While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the claims.