ELECTROMAGNETICALLY OPERATED SWITCH VALVE

Abstract

The pole geometry of an electromagnetic switch valve includes a cylindrical well on the pole member, which is penetrated by a cylindrical pin on the magnetic armature. This obtains a magnetic force-stroke curve that first extends proportionally starting out from the initial position of the magnetic armature and then rises progressively until the magnetic armature reaches the end position. Continuously increasing the energizing of the magnetic drive upon shifting of the magnetic armature from its initial position into its end position enables the noise formation upon the closing process of the valve to be reduced. Accordingly, the noise formation upon the opening process of the valve can be reduced when the energizing of the magnetic coil is reduced not abruptly but continuously.

Claims

1. An electromagnetically operated switch valve, comprising: a magnetic drive, comprising a magnetic coil with a central axis and a magnetic armature movable along the central axis by a stroke between an initial position and an end position, said armature forming, together with a stationary casing, a magnetic circuit and being movable from its initial position into its end position toward a pole member of the stationary casing due to electromagnetic forces upon energizing of the magnetic coil, a control for controlling the level of the energizing of the magnetic coil, and a flow opening and a sealing element for closing the flow opening, the sealing element being coupled with the magnetic armature or formed by the magnetic armature, wherein the magnetic drive possesses a magnetic force-stroke curve which altogether tends upwards starting out from the initial position of the magnetic armature up to the end position of the magnetic armature, and that the control is set up to increase or reduce or both increase and reduce the energizing of the coil during the motion of the magnetic armature between its initial position and its end position.

2. The valve according to claim 1, wherein the magnetic force-stroke curve rises progressively before reaching of the end position of the magnetic armature.

3. The valve according to claim 1, wherein the magnetic force-stroke curve has a proportional course, followed by a progressive course, from the initial position of the magnetic armature up to the end position of the magnetic armature.

4. The valve according to claim 3, wherein the proportional course of the magnetic force-stroke curve extends over at least 50% of the stroke.

5. The valve according to claim 3, wherein the magnetic force changes by at most 20% in the region of the proportional course of the magnetic force-stroke curve.

6. The valve according to claim 1, wherein the pole member of the stationary casing has a cylindrical well which the magnetic armature penetrates with an axial pin or the magnetic armature has the well and the pole member the pin.

7. The valve according to claim 6, wherein the well of the pole member has a depth h.sub.6 and the pin of the magnetic armature an axial length of respectively 1.5 mm, the well of the pole member an inner diameter of more than 8 mm and the pin of the magnetic armature an outer diameter of less than 8 mm, at an outer diameter of the magnetic armature of at least 9 mm, or a corresponding multiple of the above-mentioned values.

8. The valve according to claim 1, wherein the control is set up to increase the energizing of the coil continuously during the motion of the magnetic armature from its initial position into its end position.

9. The valve according to claim 1, wherein the control is set up to increase the energizing of the coil linearly during the motion of the magnetic armature from its initial position into its end position.

10. The valve according to claim 1, wherein the control is set up to increase the energizing of the coil further after reaching of the end position of the magnetic armature.

11. The valve according to claim 1, wherein the control is set up to lower the energizing of the coil to a constant value after reaching of the end position of the magnetic armature.

12. The valve according to claim 1, wherein the control is set up to reduce the energizing of the coil during the motion of the magnetic armature from its end position into its initial position.

13. The valve according to claim 1, wherein the control is set up to reduce the energizing of the coil such that when the magnetic armature reaches its initial position the magnetic force is at a positive value which is lower than the spring force of a return spring coupled with the magnetic armature.

14. The valve according to claim 1, wherein the valve is a pressure-compensated seat valve.

15. The valve according to claim 15, wherein the seat valve possesses an elastic sealing element.

Description

[0020] Hereinafter the invention will be explained by way of example with reference to the accompanying drawings. Therein are shown:

[0021] FIG. 1 an electromagnetically operated seat valve according to a preferred embodiment in the energized state;

[0022] FIG. 2 a detail of the switch valve according to FIG. 1 in the unenergized state;

[0023] FIG. 3 a current-time curve for the energizing of the magnetic drive of the seat valve from FIG. 1; and

[0024] FIG. 4 a force-stroke curve family for the seat valve from FIG. 1.

[0025] FIG. 1 shows an electromagnetic seat valve 1 according to a preferred embodiment example. The seat valve 1 possesses a flow opening 2 with a sealing seat 3 which is closable by a sealing element 4. The sealing face of the sealing element 4 is elastically deformable to guarantee a reliable sealing of the flow opening 2, and is formed by an elastomer material. The sealing element 4 is seated at the front axial end of a plunger 5 which is coupled via a connection rod 6 with a magnetic armature 7 which is movable axially along a central axis of a magnetic coil 11. It is in principle conceivable to fasten the sealing element 4 immediately to the magnetic armature 7. It is even conceivable that the elastomer material is arranged on the side of the sealing seat 3, and the sealing element 4 is formed without any elasticity by the axially front end of the magnetic armature 7 itself. In the represented embodiment example, the plunger is firmly seated on the connection rod 6 which in turn is firmly seated in the magnetic armature 7. This results in a structural group associated with the magnetic armature 7, consisting of sealing element 4, plunger 5, connection rod 6 and magnetic armature 7.

[0026] The movable magnetic armature 7 is part of an iron circuit or magnetic circuit to which a stationary pole member 8 also belongs. Between the magnetic armature 7 and the pole member 8 there is a working air gap 9 which enables the magnetic armature 7 to move axially toward the pole member 8 when the sealing element 4 is brought into its closed position, which is represented in FIG. 1. In said closed position, the magnetic armature 7 is located in its end position in which the working air gap 9 is reduced to a residual remanence distance of about 0.2 mm.

[0027] Electrically energizing the coil 11 surrounding the magnetic armature 7 and the pole member 8 causes a magnetic circuit penetrating the magnetic armature 7 and the pole member 8 to be generated in such a way that there acts between the pole member 8 and the magnetic armature 7 via the working air gap 9 a magnetic attraction which counteracts the mechanical load of a return spring 10 and overcomes it. Said magnetic force holds the magnetic armature 7 in its end position represented in FIG. 1, and thus the seat valve 1 in its closed position. As soon as the energizing of the magnetic coil 11 is reduced to zero or at least to the extent that the resultant magnetic force is lower than the spring force of the return spring 10, the magnetic armature moves into its initial position, which is shown in the detail view in FIG. 2. The working air gap 9 then increases for example to about 1.7 mm. The stroke therefore amounts to 1.5 mm in this case.

[0028] The pole contour is specially configured to attain a force-stroke curve that first assumes a proportional course as horizontal as possible, followed by a course rising progressively as strongly as possible, starting out from the initial position s.sub.0 of the magnetic armature 7 as shown in FIG. 2 up to the reaching of the end position s.sub.1 of the magnetic armature 7 as shown in FIG. 1. For this purpose, the pole contour is configured on the pole member side with a cylindrical step as a cylindrical well or quasi-cylindrical well 8a into which the magnetic armature 7 moves with a likewise cylindrical or at least quasi-cylindrical axial pin 7a. Cylindrical is understood within the context of the invention to include a deviation from the cylindrical axis up to a conicity of 10 of the pole well 8a and/or of the magnetic-armature pin 7a, with the deviation preferably being below 10, particularly preferably 5 or therebelow.

[0029] There then results a force-stroke curve as shown in the curve family according to FIG. 3, this curve being attainable with the following concrete pole and magnetic-armature dimensions: the depth h.sub.6 of the cylindrical well 8a of the pole member 8 and also the axial length of the pin 7a of the magnetic armature 7 respectively amount to 1.5 mm; the cylindrical well 8a of the pole member 8 possesses an inner diameter d.sub.6 of 8.05 mm and the pin 7a of the magnetic armature an outer diameter d.sub.7 of 7.65 mm, so that a radial remanence distance between pole member 8 and magnetic armature 7 amounts to about 0.2 mm. The outer diameter D.sub.7 of the magnetic armature 7 itself amounts to 9.23 mm, as does the outer diameter of the pole member 8 adjacent to the working air gap 9. For smaller or larger magnetic drives said dimensions can scale downward and upward approximately linearly, with the force-stroke curve being further adaptable by fine adjustment of the dimensions.

[0030] In FIG. 3 is represented the force-stroke curve of the above-described magnetic drive for different energizing levels of the magnetic coil, namely, in 0.2 ampere steps from 0.2 A to 2 A. Likewise shown is the spring characteristic of the return spring 10 over the stroke from s.sub.0=1.7 mm to s.sub.1=0.2 mm. It can be recognized that the magnetic drive extends partially proportionally, namely, in the stroke region from 1.7 mm to about 0.7 mm or 0.8 mm. The magnetic force then rises progressively over the remaining stroke region up to the end position s.sub.1=0.2 mm.

[0031] FIG. 4 shows the current-time course for the energizing of the magnetic coil 11 over a cycle starting out from the initial position s.sub.o of the magnetic armature 7 up to its end position s.sub.1 and back again into the initial position s.sub.o. Said cycle will be explained hereinafter on the basis of nine phases A to I which are defined by the time points t.sub.0 to t.sub.9, whereby phase F from the time points t.sub.5 to t.sub.6 can be arbitrarily long. Said phases A to I and time points t.sub.0 to t.sub.9 are represented as dashed curves in the force-stroke curve family according to FIG. 3, with the arrows indicating the direction in which the dashed curve is traversed.

[0032] At the time point t.sub.0 when the seat valve is to be operated, the magnetic coil 11 is first energized with a current of 1.2 A (FIG. 4). The magnetic armature is then located in its initial position with a working air gap of s.sub.0=1.7 mm (FIG. 3, time point t.sub.0). Then the current is increased linearly to 2 A over a time period of 90 ms. In so doing, the magnetic armature traverses the three phases A to C. In the initial phase A the spring force and the static friction of the sealing element 12 (FIG. 2) must first be overcome. Until the magnetic armature leaves its end position at the time point t.sub.1, the energizing has already reached a value of about 1.4 A. Said phase A lasts somewhat more than 30 ms. Thereupon the magnetic armature moves into its end position s.sub.1=0.2 mm upon further linearly rising energizing. Said phase B lasts approximately only 10 ms and is reached upon an energizing of about 1.5 to 1.7 A. The further increase of the energizing in phase C to a value of 2 A serves to avoid oscillations upon moving into the elastic sealing seat. At the time point t.sub.3 the current strength of 2 A is reached after about 90 ms, said strength then being maintained during phase D lasting about 150 ms. At the time point t.sub.4 when the sealing seat has been reliably closed, the energizing is brought down to a lower value, which is 1 A here. Said phase E amounts to about 60 ms, and the current of 1 A suffices as a rule to hold the valve reliably in the closed position while simultaneously overcoming the spring force of the return spring 10 and in particular pressure surges occurring at the flow opening The duration of holding phase F depends on the application specifications of the valve and can accordingly be arbitrarily long.

[0033] When the magnetic armature 7 is thereupon returned into its initial position the energizing is brought down to 0 A continuously, here linearly, with the magnetic armature first remaining in its end position until the magnetic force has decreased to the value of the counteracting spring force, which in the end position amounts to about 6 N (phase G, time points t.sub.5 to t.sub.6). Only thereafter does the magnetic armature move from its end position back into its initial position in phase H (time points t.sub.6 to t.sub.7), while in phase I (time points t.sub.8 to t.sub.9) the current only drops down to zero. The continuous reduction of the energizing in phase H is preferably to be selected such that the magnetic force corresponds approximately to the spring force of the return spring, so that the return spring moves the magnetic armature back but accelerates it only little due to the decelerating effect by the magnetic force. The course of phase H is slightly below the spring characteristic here, as shown in FIG. 3. It may even be expedient to increase the energizing to 0.6 A again immediately after phase G, i.e. upon reaching of 0.5 A, when the magnetic armature is just being lifted out of the end position s.sub.1 due to undershooting of the spring force, and to hold it there until the magnetic armature has reached its initial position s.sub.0 (cf. FIG. 3). By varying the spring stiffness of the return spring 10 the return motion of the magnetic armature 7 can be additionally influenced.