PROPORTIONAL VALVE

Abstract

A proportional valve is provided wherein the valve has an actuating element, a compressed-air connection, a working connection, and an air-removal connection. The valve also has three valve elements arranged one after the other and each can be moved in an axial direction. A first valve element is actuated by the actuating element, a second valve element is actuated by the first valve element, and a third valve element is actuated by the second valve element. In a base position, the valve elements are spaced apart, and, within the valve, a first sealing seat effective between the first valve element and the second valve element and a second sealing seat effective between the third valve element and the housing are arranged such that by varying the position of the first valve element, different switching states can be set.

Claims

1. A proportional valve (1), especially for actuation of a pneumatic fitting, wherein the valve (1) has an actuating element (2), a compressed-air port (5) for connection of a compressed-air supply, a working port (4) and a vent port (3), wherein the valve (1) has three valve elements (7, 8, 9) connected in series and respectively movable in an axial direction, namely a first valve element (7) actuated by the actuating element (2), a second valve element (8), which is actuated by the first valve element (7), and a third valve element (9), which is actuated by the second valve element (8), wherein, in a basic position of the valve (1), the first valve element (7) is spaced apart from the second valve element (8) and the second valve element (8) from the third valve element (9) and, within the valve (1), a first sealing seat (25) acting between the first valve element (7) and the second valve element (8) and a second sealing seat (26) acting between the third valve element (9) and the housing (15) are formed and disposed in such a way that, during variation of the position of the first valve element (7) by the actuating element (2) and of the cascade-like positioning of the axial positions of the first, second and third valve elements (7, 8, 9) that can be achieved hereby, various switched states can be set for venting of the working port (4) by placing it in communication with the vent port (3), for air admission to the working port (4) by placing it in communication with the compressed-air port (5) and for holding a pressure present at the working port (4) by shutting off the working port (4) both from the vent port (3) and the compressed-air port (5).

2. The proportional valve of claim 1, wherein the actuating element (2) operates according to a hydraulic, pneumatic or electromechanical principle.

3. The proportional valve of claim 1, wherein the actuating element (2) is formed as a pneumatic pilot valve (31), which cooperates via a control pressure chamber (14) with the first valve element (7) and which preferably comprises a piezo-bending transducer (35).

4. The proportional valve of claim 3, wherein the first valve element (7) is formed by a diaphragm disk (10) with a diaphragm-disk shank (11) that extends in axial direction and is provided with an axial bore (12), wherein the diaphragm disk (10) is spring-preloaded in a direction pointing toward the control pressure chamber (14) and for positioning of its axial position is in operative connection with a first diaphragm (13), which is pressurized on one side with the control pressure prevailing in the control pressure chamber (14).

5. The proportional valve of claim 4, wherein the second valve element (8) is formed by a valve tappet (17), which is spring-preloaded in a direction pointing toward the first valve element (7) and which, depending on axial position of the first valve element (7), is spaced apart from the diaphragm-disk shank (11) or bears thereon, wherein the first sealing seat (25) is formed at the contact face between diaphragm-disk shank (11) and valve tappet (17).

6. The proportional valve of claim 4, wherein the third valve element (9) is formed by a base element (18), which is spring-preloaded against a second sealing seat (26) in a direction pointing toward the valve tappet (17) and can be lifted from the second sealing seat (26) by axial displacement of the valve tappet (17) that has been brought into contact on the base element (18).

7. The proportional valve of claim 1, wherein a surface (24, 27) forming the first and/or second sealing seat and/or interacting therewith for adjustment of the leak rate and/or for improvement of the regulation behavior is made of a polymer material.

8. The proportional valve of claim 5. Wherein the vent port (3) discharges into a continuously vented vent chamber (22) of the valve (1), which is fluidically in communication with the working port (4) via the axial bore (12) of the diaphragm-disk shank (11) when the diaphragm-disk shank (11) is not bearing on the valve tappet (17) and is fluidically separated from the working port (4) when the diaphragm-disk shank (11) is in sealing contact on the valve tappet (17).

9. The proportional valve of claim 8, wherein the vent chamber (22) is bounded by the first diaphragm (13) and a second diaphragm (21), wherein the diaphragm-disk shank (11) extends with its free end axially through the second diaphragm (21).

10. The proportional valve of claim 9, wherein a working pressure chamber (23) in communication with the working port (4) of the valve (1) is bounded by the second diaphragm (21) and the second sealing seat, wherein the working pressure chamber (23), depending on position of the diaphragm disk (10), of the valve tappet (17) and of the base element (18), is fluidically in communication with the compressed-air port (5) or the vent port (3) or is separated from the compressed-air port (5) and vent port (3).

11. The proportional valve of claim 4, wherein spring elements (16, 20) preloading the diaphragm disk (10) and/or the base element (18) are respectively braced on a housing (15) of the valve (1).

12. The proportional valve of claim 11, wherein the diaphragm disk (10) is preloaded with at least three spring elements (16), which are disposed equidistant from an axial central axis (M) of the diaphragm disk (10), which are offset, in pairs, by the same angle () relative to one another and which are braced on the housing (15) of the valve (1).

13. The proportional valve of claim 9, wherein the diaphragm disk (10), especially in the region of the diaphragm-disk shank (11), is joined to the second diaphragm (21), wherein the second diaphragm (21) provides radial bearing for the axially oriented diaphragm disk (10).

14. The proportional valve of claim 6, wherein the valve tappet (17) is preloaded in the direction of the diaphragm-disk shank (10) by a spring (19) braced on the base element (18).

15. The proportional valve of claim 5, wherein the unactuated valve tappet (17) is distant by a certain displacement path from the base element (18) bearing on the second sealing seat.

16. The proportional valve of claim 6, wherein the spring elements (16, 19, 20) preloading the diaphragm disk (10), the valve tappet (17) and the base element (18) have spring characteristics that are different and matched to one another.

17. The proportional valve of claim 16, wherein the spring stiffness of the spring element (20) preloading the base element (18) is greater than the spring stiffness of the spring element (19) preloading the valve tappet (17) and in that the spring stiffness of the spring element (19) preloading the valve tappet (17) is greater than the spring stiffness of the spring element (16) preloading the diaphragm disk (10).

18. The proportional valve of claim 3, wherein the valve (1) further has a pressure regulator (6) for setting the pressure present at a pneumatic inlet (33) of the pilot valve (31).

Description

BRIEF DESCRIPTION OF THE DRAWING

[0037] An exemplary embodiment of the invention will be explained in more detail hereinafter on the basis of the drawing, wherein

[0038] FIG. 1 shows a section through an exemplary embodiment of an inventive valve and

[0039] FIG. 2 shows a schematic illustration of the arrangement of the spring elements preloading the first valve element in the exemplary embodiment according to FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] FIG. 1 shows an exemplary embodiment of an inventive proportional valve 1, which is provided with an actuating element 2 having the nature of a pneumatic pilot valve 31. The structure of this pilot valve 31 will be explained in still more detail hereinafter.

[0041] Valve 1 further has a vent port 3, a working port 4 for connection of a pneumatic fitting (not illustrated) to be actuated with valve 1 and a port 5 for a compressed-air supply with a predetermined air pressure of 8 bar, for example. Furthermore, a pressure regulator 6 is provided, with which a pressure of 1.2 bar, for example, which is lower than the pressure prevailing for the compressed-air supply at port 5, can be drawn therefrom as input pressure for the pneumatic pilot valve acting as actuating element 2. Since pressure regulators are known as such in diverse respects in the prior art and their specific configuration is ultimately not relevant for the present invention, a more detailed description of their functional principle will not be provided here.

[0042] Valve 1 further has three valve elements 7, 8, 9 connected in series and respectively movable in an axial direction according to double arrow R.

[0043] In this connection, first valve element 7 (topmost in FIG. 1) comprises a diaphragm disk 10 and a diaphragm-disk shank 11 with an axial bore 12.

[0044] Diaphragm disk 10 is in operative connection (via a mechanical coupling in the present case) with a first diaphragm 13, wherein a control pressure chamber 14 is formed above first diaphragm 13 and diaphragm-disk 10. The air pressure prevailing in control pressure chamber 14 is regulated by pilot valve 31 functioning as actuating element 2. Furthermore, first valve element 7 (formed by diaphragm disk 10 plus diaphragm-disk shank 11) is spring-preloaded in (axial) direction relative to control pressure chamber 14. For this purpose, in total three spring elements (springs) 16 braced on housing 15 of valve 1 are provided in the present exemplary embodiment. Only one of those (left of center axis M) lies in the section plan in FIG. 1, while the other two spring elements (of which only one is visible in FIG. 1) lie in front of or behind the section plane. These three spring elements 16 are respectively disposed equidistant (i.e. with the same radial spacing) from center axis M, and in the plane passing perpendicularly through center axis M are offset, in pairs, by the same angle a of 120 relative to one another (i.e. around center axis M), so that, relative to the axial center axis M, completely symmetric preloading of first valve element 7 in the direction of control pressure chamber 14 is achieved. FIG. 2 illustrates this symmetric arrangement of the total of three spring elements 16 present here.

[0045] Second valve element 8 in the present case is formed by a valve tappet 17 and third valve element 9 by a base element 18. In this connection, valve tappet 17 is preloaded in the direction of first valve element 7 (=diaphragm disk 10 and diaphragm-disk shank 11) by means of a spring 19, which is braced on base element 18, while base element 18 in turn is preloaded by means of a spring 20, which is braced on housing 15.

[0046] In the basic position of valve 1 illustrated in FIG. 1, all three axially movable valve elements 7, 8, 9 are preloaded in the same direction, but are spaced apart from one another in pairs.

[0047] Diaphragm-disk shank 11 is coupled with a second diaphragm 21, which circumferentially surrounds diaphragm-disk shank 11 sealingly and separates (continuously vented) vent chamber 22, which is disposed between first diaphragm 13 and second diaphragm 21 and which leads to vent port 3, from a working pressure chamber 23 leading to working port 4. This second diaphragm 21 may serve simultaneously as radial bearing of the diaphragm-disk shank. By virtue of the spacing present between the free end of diaphragm-disk shank 11 and valve tappet 17 in the basic position of valve 1, working pressure chamber 23 (and thus also a pneumatic fitting connected to working port 4) is vented in the valve position illustrated in FIG. 1.

[0048] At its top face pointing toward diaphragm-disk shank 11, valve tappet 17 has a polymer material, which serves sealing face 24 and on which a lower edge 25 of diaphragm-disk shank 11 can come into contact to form a first sealing seat. Depending on the hardness of the polymer, this compliant sealing face permits particularly precise proportional fine regulation during positioning of the valve in the vicinity of the contact area.

[0049] When thereforeby appropriate increase of the pressure prevailing in control pressure chamber 14first valve element 7 is displaced so far that lower edge 25 of diaphragm-disk shank 11 comes sealingly into contact on top face 24 of valve tappet 17, the communication through axial bore 12 of diaphragm-disk shank 11 that existed between vent chamber 22 and working pressure chamber 23 is blocked, whereby the previous venting of working pressure chamber 23 is canceled.

[0050] A second sealing seat is formed in the illustrated exemplary embodiment of a valve 1 by a sealing edge 26, which is integral with the housing and in FIG. 1 is pointing downward, and against which base element 18 functioning as third valve element 9 is preloaded by means of spring 20, wherein here a sealing face 27 of a polymer material, interacting with sealing edge 26 to form the second sealing seat, is provided in turn on the base-element side. A pressure supply chamber 28 in communication with port 5 for the pressure supply is situated underneath the second sealing seat, and is therefore separated fluidically from working pressure chamber 23 precisely when base element 18 bears sealingly with its top face on sealing edge 25.

[0051] Thus, only whenby suitable actuation of first valve element 7 by means of actuating element 2first valve element 7 has been displaced so far that first valve element 7 bears on second valve element 8 and second valve element 8 bears on third valve element 9, does a further increase of the control pressure in control pressure chamber 14 cause third valve element 9 (=base element 18) to be lifted from the second sealing seat, whereby working pressure chamber 23 is placed fluidically in communication with the pressure supply. During actuation of third valve element 9, it is of advantage that a hard stop is formed between valve tappet 17 and base element 18.

[0052] Last but not least, the particularly good regulation behavior of the described valve is also achieved on the basis of the spacings provided in the basic state between the first, second and third valve elements 7, 8, 9, since hereby the various fluidic states of the valve can be differentiated particularly well and simply activated.

[0053] Regulation of such a valve provesdespite the cascade-like configurationotherwise to be particularly simple. For this purpose, it is possible to provide a magnetic element 29 on first valve element 7 (e.g. in the region of the diaphragm-disk rim), so that, by using a suitable sensor 30, the axial position of first valve element 7 can be determined precisely.

[0054] By virtue of the purely mechanical coupling of the three valve elements 7, 8, 9 and because of the fixed travels, predetermined by the location of the sealing seats, between the various valve positions, it is possible to achieve regulation of the valve by utilizing (exclusively) the (axial) position of first valve element 7, which can be determined by means of sensor 30.

[0055] Finally, FIG. 1 further shows pneumatic pilot valve 31, which is used as actuating element 2. In the present case, this is configured as a proportional 3/2-way valve.

[0056] It has a pressure inlet 33, which in the present case is fed with compressed air made available by pressure regulator 6. Furthermore, a pilot-valve vent port 32 (optionally in communication with vent port 3 of valve 1) is provided, as is a pilot-valve working outlet 34, which is fluidically in communication with control pressure chamber 14 of valve 1. By means of a piezo-bending transducer 35, which can be electrically actuated and hereby swiveled in the region of its free end as indicated by double arrow B, pilot-valve working outlet 34 may now be optionally vented (i.e. placed fluidically in communication with pilot-valve vent port 33) or placed partly or completely in communication with the pressure prevailing at pressure inlet 33 of pilot valve 31. Thus, as already described, pilot valve 31, by regulating the pressure prevailing in control pressure chamber 14, can be used with particularly high regulation quality and low energy consumption as the actuating element for first valve element 7 of valve 1.