-1- 3686465 Ouick switch valve Specification The invention relates to a fast-switching valve according to the preamble of patent claim
1. In shutoff valves with a slide operation, it is known that an electromagnet either pushes the valve slide situated in a valve bore against the force of a restoring spring in an opening direction (NC = normally closed), or that the electromagnet pushes the valve slide against the force of the restoring spring in a closing direction (NO = normally open). US 4,155,535 discloses a valve slide, the groove of which has a conical section on the inflow side and the outflow side. Both conical sections are slightly inclined and arranged symmetrically to each other. Fast-switching valves in both of the above-mentioned designs are known, which upon movement of the valve slide in the opening direction simultaneously produce a first connection from an inflow channel to a first outflow channel and a second connection from the same inflow channel to a second outflow channel. The two outflow channels are once again connected to each other downstream from the fast-switching valve. For this, the valve slide has two axially neighbouring necks or encircling grooves, between which the inflow channel emerges into the valve bore. After the opening of the fast- switching valve, both grooves receive flow in the axial direction. Thanks to the twofold opening cross section, a prompt and large volume flow is made possible through the opened fast-switching valve even already after a slight opening movement. Publication DE 2009 060 032 Al discloses such a fast-switching valve, the valve housing of which is produced in a cartridge design, so that the two outflow ports and the inflow port arranged between them are situated on the outer periphery of the substantially circular cylindrical valve housing. A first groove receives an axial flow from the inflow channel to the first outflow channel in an opening direction of the valve
-2- 3686465 slide, while a second groove receives an axial flow from the inflow channel to the second outflow channel in the closing direction of the valve slide.
Thanks to the oppositely directed flow through the two grooves, hydrodynamic axial forces on the valve slide are in part mutually cancelled out, so that the force or energy required to move the valve slide is minimized.
Thanks to the similar configuration of the two grooves, the hydrodynamic axial forces are equal in the fully opened state of the fast-switching valve, since both grooves receive the same kind or the same form of flow through them.
Accordingly, the invention is based on the problem of creating a fast-switching valve in which the opening movement is assisted.
This problem is solved by a fast-switching valve having the features of patent claim 1.
Further advantageous embodiments of the invention are described in the dependent patent claims.
The claimed fast-switching valve has a valve bore in which a valve slide is guided.
The valve slide has on its outer periphery a first groove and a second groove spaced axially apart, which can also be called necks.
The fast-switching valve has a common inflow channel, which in a closing position of the valve slide is only in fluidic connection with one groove, and which in an opening position of the valve slide is in fluidic connection with both grooves.
In the opening position, the first groove can receive a flow in a closing direction to a first outflow channel, while the second groove can receive a flow in an opening direction (situated opposite the closing direction) to a second outflow channel.
According to the invention, in a transitional region from the first groove to a control edge of the first groove on the outflow side there is formed a conical section on the outflow side, the angle of inclination of which is less than 40 degrees relative to a longitudinal axis of the valve slide.
Hence, in the flow through the first groove a decreased axial force is generated in the closing direction as compared to the prior art.
Thus, a fast-switching valve is created, in which the opening movement is assisted.
-3- 3686465 It has been found that the angle of inclination of the conical section on the outflow side should be preferably 25 to 35 degrees, especially preferably around 30 degrees, in relation to the longitudinal axis of the valve slide.
According to the invention, in a transitional region from a control edge of the first groove on the inflow side to the first groove there is formed a conical section on the inflow side, the angle of inclination of which is less than 90 degrees relative to the longitudinal axis of the valve slide.
During flow through the first groove in the closing direction, this conical section on the inflow side generates an axial force in the opening direction.
In particular, this axial force is greater than that of the prior art.
Hence, the opening movement is further assisted.
It has been found that the angle of inclination of the conical section on the inflow side should be preferably 50 to 70 degrees, especially preferably around 60 degrees, in relation to the longitudinal axis of the valve slide.
Between the conical section on the inflow side and the conical section on the outflow side there is also formed according to the invention a middle conical section.
Preferably, the extension of this section along the longitudinal axis is greater than the extensions of the conical section on the inflow side and the conical section on the outflow side.
It has been shown that the angle of inclination of the middle conical section should be less than 10 degrees, preferably around 6 degrees, in relation to the longitudinal axis of the valve slide.
Between the conical section on the inflow side and the control edge on the inflow side there can be situated an annular end face similar to the prior art, having an angle of inclination of around 90 degrees with respect to the longitudinal axis of the valve slide.
The annular end face is significantly smaller than that of the prior art on account of the presence of the conical section on the inflow side.
In one modification of the first groove, between the conical section on the inflow side and the middle conical section there is provided a circular cylindrical section with no
-4- 3686465 inclination relative to the longitudinal axis.
Between the conical section on the inflow side and the circular cylindrical section and/or between the middle conical section and the conical section on the outflow side, a fillet or fillets is/are preferably provided.
Especially preferably, the fast-switching valve is configured in normally open design, so that an actuator acts in the closing direction while the force of a restoring spring acts in the opening direction.
Hence, the configuration of the first groove according to the invention assists the restoring spring of the fast-switching valve when this is supposed to guickly open the closed fast-switching valve.
If the actuator is an electromagnet, the configuration according to the invention of the first groove assists the restoring spring of the fast-switching valve when it needs to overcome the remanent magnetism after the switching off of the electromagnet and when it should guickly open the closed fast-switching valve.
Regarding the second groove, a transitiona] region from a control edge on the inflow side to the second groove should preferably have an annular end face on the inflow side with an angle of inclination of around 90 degrees relative to the longitudinal axis of the valve slide, and/or a transitional region to a control edge of the second groove on the outflow side should preferably have an annular end face on the outflow side with an angle of inclination of around 90 degrees relative to the longitudinal axis of the valve slide.
In this way, the volume flow across the second groove is already at maximum for a minimal opening movement.
Between the two annular end faces there is provided a circular cylindrical section with no inclination relative to the longitudinal axis.
A fillet is provided between the circular cylindrical section and each annular end face.
Each of these fillets can have two similar, yet different fillet radii.
In one preferred modification of the fast-switching valve according to the invention, at least one venting channel is provided in its valve housing, in which the valve bore is also formed, by which an armature space is connected to an outside of the valve housing.
In this way, the unavoidable inclusion of air from after the assembly of the fast-switching
-5- 3686465 valve can be moved from the armature space to the outside. In place of air, fluid (especially a pressurized agent, such as oil) enters the armature space. This serves to stabilize the switching time by reducing the drift of the switching time. When the valve housing is formed in a cartridge design, the venting channel can be arranged straight and/or parallel to the valve slide and emerge on the outside at the front end. An exemplary embodiment of the fast-switching valve according to the invention is presented in the figures. There are shown: Figure 1, in a longitudinal cross section, the fast-switching valve according to the invention in the exemplary embodiment, Figure 2, a region of the longitudinal cross section of the fast-switching valve of Figure 1 in an opened state, Figure 3, a region of the longitudinal cross section of the fast-switching valve of Figure 1 in a closed state, Figure 4, in an enlargement, a region of the longitudinal cross section of the fast- switching valve of Figure 2 in an opened state, Figure 4a, in an enlargement, a first groove of the valve slide from the preceding figures, and Figure 4b, in an enlargement, a transitional region on the outflow side of a second groove of the valve slide from the preceding figures. Figure 1 shows the exemplary embodiment of the fast-switching valve according to the invention in a longitudinal cross section. The fast-switching valve has a sleeve-like, essentially rotationally symmetrical valve housing 1, in the valve bore 7 of which a valve slide 2 can be moved through an electromagnet 3 against the force of a restoring spring
5. More precisely put, the valve slide 2 can be pulled along its longitudinal axis 9 through the electromagnet 3 from the opened position shown in Figure 1 against the force of the restoring spring 5 (to the left in Figure 1) into a closed position. For this, the electromagnet 3 has a pole tube or a magnetic pot 4, in which a coil 6 is arranged. Upon
-6- 3686465 energization of the coil 6 through a power supply 8, a disc-shaped flat armature 10 is pulled in the closing direction (to the left in Figure 1), being secured to an end portion of the valve slide 2.
The flat armature 10 is received in an armature space 12, being connected by venting ducts 14, distributed evenly on the periphery of the valve housing 1 and arranged outside the valve bore 7 and parallel to it, to an end face 16 of the valve housing 1 facing away from the power supply 8. By virtue of the design of the fast-switching valve according to the invention, it is unavoidable for air to be present in the armature space 12 during the assembly process.
This can only be expelled by the operation of the fast-switching valve and the leakage pressure applied, for example of 3 - 5 bar.
This has an influence on the drift of the switching time over the course of time, which is intensified in the installation positions "upright" and "upside down". This drift needs to be compensated, in order to be able to safely fulfil an application of the fast-switching valve.
Thanks to the venting ducts 14, the exchange of the fluid (especially the pressurized agent, such as oil) and the assembly-related trapped air in the armature space 12 is significantly improved, replacing the air with the fluid.
This serves for stabilizing the switching time during the operation of the fast-switching valve, in which the drift of the switching time is reduced.
The electromagnet 3 is closed by a cover 18 with an encircling seal, the cover 18 being tensioned against the electromagnet 3 by a closure piece 20, screwed into the end portion of the valve housing 1. The power supply 8 of the electromagnet 3 is fastened on an outer end face of the closure piece 20, two electrical leads being arranged inside the closure piece 20, of which only one lead can be seen in Figure 1.
Thanks to a flange 22, which is fastened by means of a screw thread to the closure piece 20, the valve housing 1, configured in cartridge design, can be held in a valve block (not shown). For this, three annular connection regions A1, P, A2, separated from each other by respective seals, and connected to corresponding pressure chambers of the valve bore 7, are provided on the outer periphery of the valve housing 1 in the way familiar from the prior art (DE 10 2009 060 032 Al).
-7- 3686465 Figure 2 shows a region of the longitudinal cross section of the fast-switching valve of Figure 1. This shows (as does Figure 1) the opened state of the fast-switching valve.
For this, the valve slide 2 with the electromagnet 3 switched off has been pushed by the restoring spring 5 (to the right in Figure 2) in the opening direction 24. Radially merging inflow channels P are then connected on the one hand through a first groove 26 to first outflow channels A1 and on the other hand through a second groove 28 to second outflow channels A2. The grooves encircle the valve slide 2 and can also be called necks.
In the opened state, the two grooves 26, 28 receive an axial flow in different directions 24, 30. More precisely, the second groove 28 receives a flow in the direction of the opening direction 24 of the valve slide 2, while the first groove 26 receives a flow in a closing direction 30. Figure 3 shows the cutout portion of the longitudinal cross section of Figure 2, where the valve slide 2 is moved in the closing direction 30. For this, the electromagnet 3 is energized, so that its magnetic pot 4 attracts the flat armature 10, which carries along the valve slide 2 secured to it.
The fluid (especially a pressurized agent, such as oil), which has replaced the assembly-related air, and which was present in the wedge-shaped region of the armature space 10 between the magnet 3 and the flat armature 10, is pushed during the closing movement by through openings 32 distributed on the periphery (to the right in Figure 3) through the flat armature 10 into the armature space 12. In the closed state of the fast-switching valve shown in Figure 3, the first groove 26 is still connected to the first outflow channel Al, yet separated from the inflow channel P.
Furthermore, in the closed state of the fast-switching valve, the second outflow channel 28 is still connected to the inflow channel P, yet separated from the second outflow channel Al.
Figure 4 shows in turn an enlargement from Figure 2 with the opened state of the valve slide 2. It can be seen here that the first groove 26 has a configuration differing from that of the second groove 28. Each groove 26, 28 extends from a control edge 32, 34 on the inflow side to a control edge 36, 38 on the outflow side.
-8- 3686465 Figure 4a shows the first groove 26 greatly enlarged.
It can be seen that, in the flow direction (seen from right to left in Figure 4a), starting from the control edge 32 on the inflow side, there is provided at first an annular end face 40, the radial extension of which is comparatively small.
Next to this is provided a conical section 42 on the inflow side having an axial extension 42a.
Next comes a fillet 44 having an axial extension 44a.
Then comes a region with maximum depth of the groove 26, which is formed by a circular cylindrical section 46 having an axial extension 46a.
In the now following regions, the fluid (especially a pressurized agent like oil) is taken further radially outward with a minimal axial force deployed on the valve slide 2. This occurs, at first, through a middle conical section 48 having an axial extension 48a and through a following fillet 50 having an axial extension 50a and finally through a conical section 52 on the outflow side having an axial extension 52a.
The conical section 42 on the inflow side has an angle of inclination 42b of around 60°, the middle conical section 48 has an angle of inclination 48b of around 6° and the conical section 52 on the outflow side has an angle of inclination 52b of around 30°. In the exemplary embodiment shown, the following size relations of the axial extensions 44a, 46a, 48a, 50a, 52a apply: extension 48a of the middle conical section > extension 46a of the circular cylindrical section > extension 50a of the fillet 50 > extension 44a of the fillet 44 > extension 52a of the conical section 52 on the outflow side > extension 42a of the conical section 42 on the inflow side.
Figure 4b shows a cutout portion of the second groove 28. More precisely, a smaller portion of the circular cylindrical section 54 is shown, following which in the flow direction (from left to right in Figure 4b) there is provided a two-piece fillet 56, the two pieces of which have a somewhat different radius of curvature.
The second piece of the fillet 56 adjoins an annular end face 58, followed by the control edge 36 on the outflow side of the second groove 28.
The region between the control edge 34 on the inflow side of the second groove 28 and the circular cylindrical section 54 of the second groove 28 is configured accordingly (mirror symmetry, looking in the longitudinal cross section).
-9- 3686465 With the configuration of the first groove 26 according to the invention, having the conical section 42 and preferably having the much less inclined middle conical section 48 and having the conical section 52 on the outflow side, under a radially inward directed incoming flow and an axial flow through the first groove 26 (directed to the left in Figures 4 and 4a), an axial force is generated according to the invention in the opening direction 24 of the valve slide 2. In this way, the restoring springs 5 (see Figures 1 to 3) of the fast-switching valve designed as a normally open (NO) valve are supported and a secure opening is achieved after switching off the electromagnet 3.
The second groove 28 is optimized for maximum flow already with a slight opening cross section.
There is disclosed a fast-switching valve having two grooves 26, 28 of the valve slide 2 receiving a flow at the same time and in different axial directions 24, 30. The first groove 26 is optimized in terms of strengthening the axial force against the flow direction 30 of the groove 26. The second groove 28 is optimized in terms of its volume flow already at a slight opening cross section.
The second groove 28 can be formed according to the prior art.