DE20218622U1 - Microvalve with 3/2 function having a control section to seal the tube channel and open a fluid channel - Google Patents

Abstract

The microvalve has a valve housing (2) defining a through channel (4) running between first and second channel ports (5,6). The channel has a side opening (12) forming a third channel port. A tubular control element (14) extends between the first and second ports and bridges the third. A tubular channel (15) passes axially through the control element. The control element has a fixed end section (16) sealingly connected to the first port and an opposite rubber elastic deformable end or control section (17). The control end (17) can take up a first or a second switch position under the action of an actuator (32). In the first position when the tubular channel (15) is simultaneously open, there is a sealed connection between the control section and the second port. In the second position the control end is restricted so that the tubular element is blocked off and a fluid passage (32) is opened between the second and third ports.

Description

G 22170 - les 9. October 2 0

FESTO AG & Co, 73734 Esslingen Micro valve

The invention relates to a micro valve that can be operated with a 3/2 functionality.

Microvalves have so far usually been designed as seat valves with electrostatic actuation. EP 0485739 B1 is an example in this context. The disadvantage of these known microvalves is the limitations in the achievable flow values.

It is the object of the present invention to provide a microvalve which, despite miniaturized dimensions, allows high flow rates of the fluid to be controlled.

This object is achieved by a micro valve with 3/2 functionality, with a valve housing which defines a through-channel running between a first and a second channel connection, which has a lateral opening forming a third channel connection, and with a tube-like control element which extends between the first and the second channel connection, bridging the third channel connection and which is axially connected by a

Pipe channel is penetrated and has a fixed end section (fastening section) which is permanently connected to the first channel connection under a seal, and an opposite, rubber-elastically deformable end section (control section), wherein the control section can optionally assume a first or a second switching position under the influence of actuating means, wherein in the first switching position, with the pipe channel simultaneously open, there is a sealed connection between the control section and the second channel connection and in the second switching position the control section is constricted in such a way that the pipe channel is tightly closed off and at the same time a fluid passage is released between the second and the third channel connection.

The microvalve according to the invention is usually operated in such a way that the first channel connection belongs to a feed channel, the second channel connection to a working channel and the third channel connection to a relief channel or - in the case of a pneumatic valve - to a vent channel. In the first switching position of the control section, the full cross-section of the pipe channel can thus be made available to the pressure medium to supply a consumer connected to the working channel. The flow is not impeded, so that high flow values and a high level of efficiency are achieved. The other, second switching position is obtained by constricting the control section, which

in particular by squeezing the control section together. Opposite wall areas of the control section come into close contact with one another so that the pipe channel is blocked. The changing outer contour of the control section means that the tight connection to the second channel connection is simultaneously eliminated and the latter is in fluid communication with the third channel connection, past the side of the compressed control section. In the aforementioned application form, this leads to a relief or venting of the consumer connected to the working channel. Since, unlike with a seat valve, the pipe channel does not have to be closed against the flow force to block it, the corresponding switching process requires only low actuation forces, which allows the micro valve to be very small. If the pipe channel is then released again and the third channel connection is separated from the second channel connection again, the pressure prevailing at the first channel connection can be made available to the second channel connection immediately, with no dead volume occurring. The micro valve can be implemented very cost-effectively overall.

Advantageous further developments of the invention emerge from the subclaims.

A rubber-elastic, deformable hose body is provided as a control element. This can be used to

It can also be designed with a very small cross-section of the pipe channel defined by it at low cost. However, it is also possible to form the hose body using two membrane elements that are placed one on top of the other and connected to one another at the edges with a seal, for example by welding, gluing or mechanical clamping. The clamping can be achieved by the valve housing itself.

It is advantageous if at least one and preferably both end sections of the control section are inserted into the associated channel section. The pressure in the pipe channel then causes the wall of the control element to be pressed against the inner circumference of the associated channel section, which creates or at least supports a sealing function.

The control element should be kept as short as possible, especially if it is made entirely of rubber-elastic material, so that it does not inflate too much when the pipe channel is pressurized, which can result in a reduction in length.

The actuating means expediently have an actuating element acting on the control element in the area of the lateral opening of the through-channel, with which an actuating force can be exerted on the control section, squeezing it together. The actuating element is preferably

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The actuating member is fixed outside the through-channel and acts from the outside, through the third channel connection, on the side wall of the control section. The actuating member is preferably designed to be at least partially spring-elastic, with particular provision being made for it to pre-tension the control section of the control element into the second switching position in the unactuated state.

To actuate the actuating element, an electrically activated drive is expediently provided, which is preferably designed as an electromagnetic drive. Due to the high actuating forces that can be achieved, such a drive is predestined for an application in which a spring force must be overcome during actuation. Less advantageous in this respect, but nevertheless usable in principle, are electrostatic or piezoelectric drives, which usually have to be operated with higher voltages.

The actuator can be housed directly in a housing chamber of the valve housing that communicates with the third channel connection. It is conveniently located on a circuit board that forms a wall section that delimits the housing chamber. Electrical connection means for electrically contacting the actuator are also conveniently located on this. In addition, the circuit board can be equipped with passive or active e-

electronic components that help activate the drive. For example, they can be used to reduce the holding current of the electromagnet or for an optical position indicator. The electronic components can be encapsulated in a potting compound for protection.

The micro valve can be designed to be either monostable or bistable. In a bistable mode of operation, the individual stable positions of the actuating element are expediently defined by a link with which a follower element, which is mounted on the actuating element in a particularly spring-elastic manner, can work together.

The invention is explained in more detail below with reference to the accompanying drawings, in which:

Figure 1 shows a schematic side view of a first design of the microvalve according to the invention, approximately along section line I-I in Figure 2,

Figure 2 shows the microvalve from Figure 1 in plan view according to arrow II and partially cut away, whereby an exploded view is chosen to illustrate a preferred integration of the drive,

Figure 3 is a simplified, enlarged schematic diagram of the microvalve according to Figures 1 and 2, omitting the drive and with the control element in the first switching position,

Figure 4 shows the arrangement from Figure 3 in cross section according to section line IV-IV,

Figure 5 is a view corresponding to Figure 3, showing the control element in the second switching position,

Figure 6 shows a cross-section through the arrangement of Figure 5 along section line VI-VI,

Figure 7, again in a schematic representation, limited to an illustration of the actuating means, shows another design of the microvalve with which a bistable mode of operation can be implemented, with the actuating element being shown when it assumes its stable basic position, and

Figure 8 shows the arrangement from Figure 7 with the loading element switched to the stable, deflected position.

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The microvalve of the embodiments shown in the drawing, designated in its entirety with reference number 1, is manufactured using known microsystem technology processes, for example by means of molding techniques, galvanic technologies or mechanical microstructuring measures.

The microvalve 1 contains a valve housing 2, which is preferably constructed from several layers 3 firmly connected to one another by gluing or bonding, which are shown as examples in Figures 3 to 6.

A linear through-channel 4 runs inside the valve housing 2, which has a first channel connection 5 at one end and a second channel connection 6 at the other end. These channel connections 5, 6 communicate with a first or second connection opening 8, 9 provided on the outside of the valve housing 2, to which fluid lines leading away, for example of a hose-shaped type, can be connected. In the preferred mode of operation shown in the drawing, the first channel connection 5 forms a feed channel to which a pressure source can be connected via the first connection opening 8. The second channel connection 2 represents a working channel to which a consumer to be operated, for example a drive that can be activated by fluid force, can be connected via the associated second connection opening 9.

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The through-channel 4 is provided between the first and second channel connections 5, 6 with a lateral opening 12 which forms a third channel connection 7. This communicates with a housing chamber 13 defined in the valve housing 2, which communicates with a third connection opening 10 which also opens out to the outside of the valve housing 2. The latter is connected to the atmosphere, so that the third channel connection 7 forms a relief channel which communicates with the environment.

If the micro valve is not used to control hydraulic media but to control compressed air, the channel connection 7 can be referred to as a vent channel. When operating with hydraulic media, the third connection opening 10 is expediently connected to a tank.

Within the through-channel 4, a tube-like control element 14 extends between the first and second channel connections 5, 6. It is coaxially penetrated by a fluid channel, referred to as tube channel 15 for easier differentiation.

The tubular control element 14 has a stationary first end section associated with the first channel connection 5, which is permanently connected to the first channel connection by sealing.

End 5 is connected and is referred to as fastening section 16. The opposite second end section of the control element 14 forms the valve member of the microvalve 1 and is designed to be elastically deformable, wherein it is referred to as control section 17.

In principle, it would be possible to form the control element 14 from several components and/or materials, so that the rubber-elastic deformability is only present in the area of the control section 17, but a rigid structure is present in the area of the fastening section 16. However, a particularly simple and yet effective structure results if the control element 14, as in the exemplary embodiment, consists in its entirety of a rubber-elastic deformable hose body 18. This hose body 18 is expediently formed from a single hose element, although it is possible to realize it - as indicated in dash-dotted lines in Figure 4 - by two membrane elements 22a, 22b lying on top of one another and firmly connected to one another at the edges with a seal.

The control element 14 bridges the lateral opening 12, whereby both the fastening section 16 and the control section 17 expediently extend a little into the respective associated first or second channel section 5, 6. For example, by welding or gluing, the fastening section 16 is fixed to the housing in such a way that a

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There is a fluid-tight connection between the pipe channel 15 and the first channel connection 5. In this case, an additional seal is not necessary.

Actuating means designated as a whole by reference numeral 23 make it possible to cause the control section 17 to optionally assume either a first switching position as shown in Figures 3 and 4 or a second switching position as shown in Figures 5 and 6.

The loading means 23 contain, among other things, a movable loading member 24 which is able to act on the control section 17 of the control element in the region of the lateral opening 12 or the third channel connection 7 in order to deform it to a greater or lesser extent transversely to the longitudinal direction of the control element 14 for the purpose of releasing or closing the pipe channel 15.

In the exemplary embodiment, the loading member 24 is at least partially spring-elastic. It is fixed to the housing with respect to the valve housing 2 by means of a fastening region 25, and it also has an loading section 26 that can be moved relative to the fastening region 25 transversely to the longitudinal direction of the control element 14. The possible movement of the loading section 26 is indicated at 27 by a double arrow.

In the exemplary embodiments, the application section 26 is located at one end of a first spring arm 28, which is, for example, a band-shaped one and has the fastening area 25 at the other end. Within the housing chamber 13, the spring arm 28 is laid with a curved course such that its application section 26 is prestressed against the outer circumference of the control element 14 by the resulting spring force. The prestress is so strong that the application section 26 squeezes the control section 17 so that it is constricted as shown in Figures 5 and 6, with the opposite wall sections of the hose body 18 being pressed tightly against one another and the pipe channel 15 consequently being sealed off in a fluid-tight manner.

Because the resulting deformation of the outer cross-sectional contour of the control section 17 means that there is no longer complete contact between the outer circumference of the control section 17 and the inner circumference of the second channel connection 6, a gap-like fluid passage 32 is simultaneously opened up between the second channel connection 6 and the third channel connection 7.

In the microvalves 1 of the embodiments, this position of the actuating element 24 forms a stable basic position, which is given in the deactivated state of an electrically activated drive 33, which also belongs to the actuating means 23. This position corresponds to the

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Closed position of the micro valve, whereby according to the channel distribution described above the pressure source is shut off and the connected consumer is relieved via the third channel connection 7.

In order to switch the micro valve 1, which is designed as a 3/2-way valve, to an open position, the drive 33 is electrically activated. As a result, the actuating element 24 is deformed against the spring force and moved away from the control section 17. This expands due to its inherent rubber elasticity until its outer circumference rests all around on the inner circumference of the second channel connection 6. This corresponds to the first switching position shown in Figures 3 and 4, with the actuating element 24 assuming a deflected position achieved by activating the drive 33.

Due to the rubber-elastic material properties, the control section 17 is pressed tightly against the inner circumference of the second channel connection 6, so that the third channel connection 7 is separated from both the first (5) and the second (6) channel connection. At the same time, the pipe channel 15 is open, so that the first and second channel connections 5, 6 communicate with each other and pressure medium fed in via the first channel connection 5 can reach a consumer connected to the second channel connection 6.

The sealing between the deformable control section 17 and the second channel connection 6 is supported by the fluid pressure prevailing in the pipe channel 15, since this presses the wall of the control element 14 more strongly against the wall of the second channel connection 6.

Since in the exemplary embodiment the application force that squeezes or constricts the control section 17 in the second switching position is caused solely by the spring preload of the application element 24, a correspondingly high actuating force is required to deflect the application element 24. For this reason, an electromagnetic drive is used as the drive 33 in the exemplary embodiment. Compared to electrostatic and piezoelectric drives, an electromagnetic converter has the advantage that it can generate high actuating forces even at low voltages. Further advantages lie in the relatively low control voltages.

In order to achieve a compact design, the drive 33 is preferably housed in the housing chamber 13. The spring-elastic loading element 24 can extend at least a short distance around the drive 33. In the exemplary embodiment, the loading element 24 is installed in such a way that it has a U-shaped course, with the drive 33 sitting inside the U.

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From Figure 2 it is clear that the drive 33 is preferably attached to one of the two large side surfaces - hereinafter referred to as the inner surface 34 - of a circuit board 36, for example a printed circuit board. This circuit board 36 forms a wall section of the housing chamber 13, so that when it is mounted, the valve housing 2 is closed and the drive 33 is installed at the same time.

Electrical connection means for the drive 33, for example plug contacts, are provided on the large outer surface 35 of the circuit board, which is opposite the inner surface 34. In addition, the circuit board 36 is equipped on the outer surface 35 with electronic components 38 which belong to an electrical circuit and are involved in activating the drive 33. They can be used, for example, to reduce the holding current of the electromagnet. If there is sufficient space, the electronic components 38 can alternatively or additionally be arranged on the inner surface 34 of the circuit board 36.

The electronic components 38 can be protected from environmental influences by means of a potting compound 42 indicated by a dot-dash line. Vias (not shown in detail) can be used for the electrical connection between the outer surface 35 and the inner surface 34.

The circuit board 36 can be glued or plugged together with the other component of the valve housing 2, for example.

An advantage of the microvalve 1 is that the housing chamber 13 is pressureless when the microvalve 1 is in the open position, so that no adverse effects occur for the circuit board 36.

As can be seen from Figures 1 and 8, the electromagnetic drive 33 has a coil core 43, against which the loading element 24 is placed in the deflected position with its first spring arm 28. In order to develop sufficient electromagnetic force for the spring deflection, a magnetic moving wedge can also be implemented. In the resting state, the spring-elastic loading element 24 is arranged with a slight inclination relative to the facing coil core surface 44.

At least in the area of the control section 17, but preferably over the entire length, the control element 14 expediently has an elongated and in particular elliptical cross-section. A particularly expedient design in this respect is shown in Figure 4. The control element 14 is arranged in such a way that the loading member 24 is connected to one of the two transverse

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sectionally longer wall sections of the control element 14 interact.

It is also advantageous if the loading member 24 has a cross-sectional profile that is convexly curved towards the control section 17 at least at its loading section 26, so that in the basic position according to Figures 5 and 6 the two opposing wall sections of the control section 17 are securely pressed against each other over their entire width. The lower wall section of the control element 14 that does not cooperate directly with the loading member 24 is supported by a support surface 47 that is fixed to the housing and has a similar curvature.

While the microvalve 1 shown in Figures 1 to 6 has a monostable design, Figures 7 and 8 reveal a further development which also allows a bistable operation.

Figure 7 shows the loading member 24 with the drive deactivated and assuming its basic position, which, as in the case of Figures 1 to 6, is a stable position since it is maintained by the spring force caused by the first spring arm 28. Figure 8 shows the loading member 24 in the deflected position, which here, however, in comparison to the design of Figures 1 to 6, represents a stable state even after the drive 33 has been deactivated.

In order to ensure this, the actuating member 24 cooperates with a guide slot 48 in that a second spring arm 29 protrudes from the first spring arm 28 in a plane parallel to the switching movement of the actuating member 24, on which a follower member 52 engaging with the guide slot 48 is arranged.

The guide slot 48 is a self-contained guide track. If, starting from the basic position, the loading member 24 is displaced in the direction of the deflected position by activating the drive 33, the follower member 52 initially runs along an inclined first track section 53 of the guide slot 48, whereby the second spring arm 49 is bent and pre-tensioned. At the end of this movement, the follower member 52 crosses a ramp 54, behind which it engages as shown in Figure 8. The loading member 24 is therefore held in the deflected position reached in this way even when the drive 33 is deactivated. The stroke of the follower member 52 and the loading section 26 covered up to that point is marked with h]_.

In the deflected position, the second spring arm 29 is still pre-tensioned to some extent. If the drive 33 is subsequently activated with another powerful current pulse, the follower element 52 moves along a second track section 55 adjoining the ramp 54 until a sloping third track section 56 adjoins it.

closes, which joins the first track section 53 at the bottom. The second spring arm 29 can then relax, with the follower member 52 snapping into the third track section 56 and following it downwards when the drive 33 is subsequently deactivated again. The downward movement is initiated by the first spring arm 28, which is now also relaxing again.

The loading element 24 thus returns to the basic position, from where a new switching cycle of the type mentioned can follow.

When completing a cycle, the follower member 52 moves through the guide slot 48 once, in the embodiment example in an anti-clockwise direction.

In order for the resilient loading member 24 to be able to carry out the desired movement, it is recommended to provide the facing coil core surface 44 with a bent profile.

If required, the microvalve 1 of Figures 7 and 8 can also be operated monostable. For this purpose, the drive 33 is only operated with the actuating element 24 in the basic position in such a way that the follower element 52 rises within the first track section 53 only to a height h.2 which is below the ramp height h^. The actuating element 24

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member 24 then returns to the basic position within the same first path section 53 when the drive 33 is deactivated.

If the microvalve is operated with the bistable function, the position of the actuating element 24 cannot be detected if the starting position is not known before commissioning. For this reason, it is recommended to provide sensor means 57 that enable the position of the actuating element 24 to be detected. It is particularly advantageous to use the electromagnetic drive 33 as the sensor means 57 by using it in a similar way to a proximity sensor.

If the user wishes that the micro valve 1 should never be able to enter the bistable function mode, corresponding measures can be implemented by means of an appropriate electronic control, but in a simpler manner with the aid of mechanical stop means 58. If necessary, these stop means 58 can be positioned in the stroke path of the actuating element 24 in such a way that it is prevented from reaching the ramp height hi . In the exemplary embodiment, the stop means 58 consist of a stop element that is eccentrically pivoted in the valve housing 2.

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Claims (20)

1. Micro valve with 3/2 functionality, with a valve housing ( 2 ) which defines a through channel ( 4 ) running between a first and a second channel connection ( 5 , 6 ), which has a lateral opening ( 12 ) forming a third channel connection ( 7 ), and with a tube-like control element ( 14 ) which extends between the first and the second channel connection ( 5 , 6 ) while bridging the third channel connection ( 7 ), which is axially penetrated by a tube channel ( 15 ) and has a stationary end section (fastening section 16 ) which is permanently connected to the first channel connection ( 5 ) in a sealed manner, as well as an opposite, rubber-elastically deformable end section (control section 17 ), wherein the control section ( 17 ) can optionally assume a first or a second switching position under the influence of actuating means ( 23 ), wherein in the first switching position, with the pipe channel ( 15 ) simultaneously open, there is a sealed connection between the control section ( 17 ) and the second channel connection ( 6 ) and in the second switching position the control section ( 17 ) is constricted such that the pipe channel ( 15 ) is tightly closed off and at the same time a fluid passage ( 32 ) between the second and the third channel connection ( 6 , 7 ) is released. 2. Microvalve according to claim 1, characterized in that the control element ( 14 ) in its entirety consists of a rubber-elastic deformable hose body ( 18 ). 3. Microvalve according to claim 2, characterized in that the hose body ( 18 ) is formed by two membrane elements lying on top of one another and firmly connected at the edges to form a seal. 4. Microvalve according to one of claims 1 to 3, characterized in that the control element ( 14 ), at least in the region of its control section ( 17 ), has an elongated and in particular elliptical cross-section. 5. Microvalve according to one of claims 1 to 4, characterized in that the control element ( 14 ) is inserted with its fastening section ( 16 ) into the first channel connection ( 5 ). 6. Microvalve according to one of claims 1 to 5, characterized in that the control element ( 14 ) projects with its control section ( 17 ) into the second channel connection ( 6 ) and in the first switching position is pressed with its outer circumference with sealing all around against the inner circumference of the second channel connection ( 6 ). 7. Microvalve according to one of claims 1 to 6, characterized in that the actuating means ( 23 ) contain an application member ( 24 ) acting on the control element ( 14 ) in the region of the lateral opening ( 12 ) of the through-channel ( 4 ), with which an application force can be exerted on the control section ( 17 ) so as to squeeze it together. 8. Microvalve according to claim 7, characterized in that the loading member ( 24 ) is at least partially spring-elastic. 9. Microvalve according to claim 8, characterized in that the loading member ( 24 ) biases the control section ( 17 ) into the second switching position in the unactuated state. 10. Microvalve according to one of claims 7 to 9, characterized in that the actuating means ( 23 ) contain an electrically activatable drive ( 33 ) provided for actuating the loading member ( 24 ), in particular an electromagnetic drive. 11. Microvalve according to claim 10, characterized in that the drive ( 33 ) is accommodated in a housing chamber ( 13 ) of the valve housing ( 2 ) communicating with the third channel connection ( 7 ). 12. Microvalve according to claim 11, characterized in that the drive ( 33 ) is fastened to a circuit board ( 36 ) which forms a wall section of the housing chamber ( 13 ) and on which electrical connection means ( 37 ) for the drive ( 33 ) are expediently also provided. 13. Microvalve according to claim 12, characterized in that the circuit board ( 36 ), in particular on the outer surface ( 35 ) opposite the housing chamber ( 13 ), is equipped with electronic components ( 38 ) which participate in the activation of the drive ( 33 ). 14. Microvalve according to one of claims 1 to 13, characterized by a monostable design, wherein the control element ( 14 ) assumes the first or second switching position in the unactuated state. 15. Microvalve according to one of claims 1 to 14, characterized by a bistable operating behavior with a spring-elastic loading member ( 24 ) which can be actuated by means of an electric drive ( 33 ) and which initially, when the drive ( 33 ) is deactivated, assumes a stable basic position due to the spring force which causes one of the switching positions of the control section ( 17 ), can be moved by temporarily activating the drive ( 33 ) into a deflected position which causes the other switching position of the control section, and is held stable in this position, even after deactivation of the drive ( 33 ), and can be moved back into the basic position by temporarily activating the drive ( 33 ) again. 16. Microvalve according to claim 15, characterized in that the control section ( 17 ) assumes the second switching position in the basic position of the loading member ( 24 ). 17. Microvalve according to claim 15 or 16, characterized in that the actuating member ( 24 ) has a follower member ( 52 ) which, during switching, moves along a guide slot ( 48 ) defining the various positions. 18. Microvalve according to claim 17, characterized in that the follower member ( 52 ) is arranged on a spring arm ( 29 ) of the loading member ( 24 ). 19. Microvalve according to one of claims 15 to 18, characterized by sensor means ( 57 ) for detecting the position of the actuating member ( 24 ). 20. Microvalve according to one of claims 15 to 19, characterized by stop means ( 58 ) which can be selectively positioned in a stop position in which they prevent switching of the actuating member ( 24 ) from the basic position into the stable deflected position.