WO2012025197A1

WO2012025197A1 - Piezoelectric valve

Info

Publication number: WO2012025197A1
Application number: PCT/EP2011/004029
Authority: WO
Inventors: Gebhard Munz
Original assignee: Festo Ag & Co. Kg
Priority date: 2010-08-24
Filing date: 2011-08-11
Publication date: 2012-03-01
Also published as: DE102010035263A1; DE102010035263B4

Abstract

The invention relates to a piezoelectric valve, which has a valve housing (3) and a control unit (23) movably arranged in the valve housing. The control unit (23) has a control body (24), which has a base section (28) and two control fingers (31a, 31b), which each protrude by means of an interconnected respective solid-body joint (35a, 35b) and which each cooperate with a respective valve seat (15a, 15b). Each control finger (31a, 31b) can be operated by a piezoelectric actuator (25a, 25b) designed as a stack translator. The activation of a piezoelectric actuator (25a, 25b) causes the control body (24) to be deflected and one of the control fingers (31a, 31b) to lift off the associated valve seat (15a, 15b).

Description

FESTO AG & Co. KG, 73734 Esslingen Piezo valve

The invention relates to a piezoelectric valve, with a valve housing, in which a movable control unit is arranged, which has a control body with a base portion and two side by side projecting from the base portion control fingers, wherein the control body is pivotally mounted at its base portion relative to the valve housing about a pivot axis and the two control fingers, each with a closure section, project beyond one of two valve seats arranged on the valve housing, the control unit also having two piezoactuators each assigned to one of the control fingers, by their individual activation the respective associated closure section with simultaneous bending of the control body against the latter Valve seat is pressed, so that the base portion including the other control finger is pivoted about the pivot axis and thereby of this other control finger associated closure portion of the associated valve seat is removed.

A piezo valve of this type known from EP 1 207 329 B1 contains a control unit arranged in a valve housing which consists of a control body with two integrated piezo actuators designed as bending transducers. The control body has a base portion pivotally mounted on the valve housing and two protruding from the base portion Bending transducer piezoelectric actuators each projecting with a closure portion via a valve seat arranged on the valve housing. Normally, the closure portions are pressed by spring means to the valve seats and each seal a valve channel. To release the largest possible flow cross section, each piezoelectric actuator can be activated so that it is pressed with its actuator force to the associated valve seat. This leads to a deflection of the control body, wherein the base portion is pivoted relative to the valve housing, wherein it entrains the other piezoelectric actuator and thus removes it from its associated valve seat.

Although the piezoelectric transducers of the known piezoelectric valve allow reliable operation and precise operation. However, the actuation force principle limits are set, which also applies to the controllable nominal diameters and pressure ranges. Thus, depending on the requirement profile, piezo valves with different sizes are made available. In order to be able to control large pressures or nominal diameters, relatively large dimensions of the control unit are therefore required.

From DE 20 2009 007 298 Ul a piezo drive for valves is described, which has a piezo stack actuator, which acts on a pivotally mounted lever, which in turn interacts with a rocker-like mounted valve member.

DE 103 03 856 B3 describes a device for switching a valve in which a designed as a piezo-translator piezoelectric actuator acts via an actuating lever on the valve to be controlled, wherein the actuating lever is connected via a solid-state joint with a housing-fixed bearing body. WO 96/19836 A1 describes a piezo-actuatable drive element which has two piezoactuators embodied as stack-type translators, which are arranged next to one another and together act on a tiltable limb.

It is the object of the present invention to provide a piezoelectric valve of the type mentioned, which can control a relatively large fluid pressure range in compact dimensions.

To solve this problem is provided in connection with the features mentioned above, that each control finger is connected via an integrated solid-state joint of the control body to the base portion and that the two piezoelectric actuators are formed by respect to the control body separate Stapeltranslatoren, each on the one hand to one of the control finger and on the other hand supported on the base portion of the control body, so that by their selective activation of the respectively associated control finger in the region of the solid-state joint with respect to the base portion is pivotable.

In this way, there is a piezoelectric valve in which the two closure sections are actuated with designed as a stack translators piezo actuators, so that very high actuation forces are available. The conceptual disadvantage of low stroke stack converters is more than compensated that the closure portions are arranged with respect to the base portion pivotable control fingers on which the stack translators act, so that by appropriate choice of different distances between the serving for pivotal solid joint and on the one hand the closure portion and on the other hand, a force transmission range of the stack translator realizes a is lisierbar, with which a relatively large stroke of the associated closure portion can be realized. Even with a relatively large stroke, this results in a very stiff control unit, ie an actuator system with a large excess of force. This allows the realization of a piezo valve with a very high controllable pressure range and accordingly a very wide field of application. Due to the solid state joints, the control body can be relatively easily manufactured and has a very good structural rigidity from home.

Advantageous developments of the invention will become apparent from the dependent claims.

Each of the controllable by the control fingers valve seats is associated with a fluid-flow valve channel. It would be possible to control the fluid transfer between these two valve channels by the control unit. It is expedient, however, the additional presence of another, third valve channel, so that there is the possibility to connect this third valve channel optionally with one or the other of the two controllable valve channels. Suitably, an embodiment of the piezo valve as a 3/3-way piezo valve, which also makes it possible to close the two controllable valve channels simultaneously and separate from the third valve channel.

The piezo valve can in principle be operated digitally as a switching valve. However, its use as a proportional valve is considered to be particularly advantageous, wherein the two piezoactuators are variably electrically actuated independently of each other, so that each closure section can continuously assume a plurality of open positions in which it is arranged at different distances from the respectively associated valve seat is. As a result, the output-side fluid pressure and / or flow can be variably set and set in a regulated manner as required.

The solid-state joints advantageously result from a respective bendable, relatively thin material web, which is connected at one end to the base portion and at the other end to the associated control finger. In this case, in particular, there is a one-piece connection. Particularly advantageous is an overall realization of the control body as a one-piece component, preferably of metal, in particular of steel.

In the area opposite the associated valve seat, each closure section expediently carries a closure surface which, in order to close a valve channel, can sealingly abut the associated valve seat. The closure surface can be part of a separate sealing element arranged on the closure section or is a direct component of the closure section, for example formed by a surface section of the control finger.

Preferably, there is a greater distance between the solid-body joint and the closure surface than between the solid-body joint and the force introduction point arranged on the control finger, against which the associated piezoactuator acts. In this way, there is an optimal stroke ratio for the pivotable relative to the base portion control finger. Even if a twenty-fold translation of Nutzhubes is made, which is for example in the range of 30 μτη, created for pneumatic applications still very rigid drive with high power surplus. This not only a very high pressure range can be covered, but result also for the required control of the valve operation significant advantages.

In particular, an L-shaped design is recommended for the control finger, wherein the longer L-leg forms the closure section and the shorter L-leg is connected to the associated solid-body joint. The force introduction point for the associated piezoelectric actuator is in this case in particular at the shorter L-leg and in particular at that outer surface of this shorter L-leg, the longer L-leg. turned away in the opposite direction.

A particularly space-saving arrangement can be obtained if the piezoelectric actuators are accommodated together in a lateral recess of the control body, which are bounded on the one hand by the adjoining the solid joints rear end portions of the control fingers and on the other hand by an opposite end wall of the base portion. The piezoelectric actuators are in this case arranged in particular such that they act on one of the two rear end sections of the control fingers at one end and on the other end are supported directly or indirectly on the inner surface of the end wall facing the recess.

The two control fingers are designed in particular identical. Their closure sections can preferably have a rod-shaped form. It is expedient to have an arrangement in which they are aligned parallel to each other with transverse spacing in the deactivated state.

It is also advantageous if the two controllable valve seats are located on the same longitudinal side of the control body. The direction of force with which the closure sections are supported on activation of their associated piezoelectric actuator on a valve seat, then is the same for both control fingers.

A particularly advantageous pivotal mounting of the control body on the base portion is realized by means of a knife edge bearing. In this case, a pivot bearing device is used which has two bearing components, which in one case is a bearing groove and in the other case is a bearing blade engaging in the bearing groove. Of these two bearing components, one is located at the base portion of the control body and the other at the valve body. Preferably, the bearing blade is arranged on the valve housing.

The bearing blade is supported on the boundary surface of the bearing groove. The base portion is therefore only loose on the pivot bearing device on the valve body. Conveniently, however, spring means are present, which are effective between the base portion and the valve housing and constantly press the base portion of the arranged on the valve housing bearing component, without hindering the pivoting movement.

The piezo valve is in particular designed so that both closure sections in the deactivated state of the respective associated piezoelectric actuator occupy a closed position sealingly abutting the opposite valve seat. When the piezo actuators are deactivated then the valve channels assigned to the two controllable valve seats are shut off. This closed position is achieved in particular by the fact that the piezo valve is equipped with spring means which are constantly effective between the valve housing and the control fingers to act on the latter in the direction of the closed position. The spring means may hereby be, for example, di- act directly on the control fingers in the area of the closure sections or in the area of the solid-state joints. If the introduction of force of the spring means in the region of the solid-state joints, so that preferably the necessary holding force can be applied to pivot in the presence of a cutting edge bearing the base portion on the valve housing.

The spring means may for example be formed by coil springs, but are preferably realized in the form of at least one leaf spring.

The two control fingers extend expediently in mutually parallel, spaced-apart Auslenkebenen extending perpendicular to the pivot axis of the existing between the base portion and the valve housing pivot bearing. The piezoelectric actuators are in this context preferably arranged so that their longitudinal axes are parallel to these Auslenkebenen, wherein expediently the longitudinal axis of a piezoelectric actuator in the one Auslenkebene and the longitudinal axis of the other piezoelectric actuator in the other Auslenkebene.

If in each case a control finger and a piezoelectric actuator are arranged axially successively, a particularly flat design of the control unit can be realized. If there is interest in a short construction, this can be realized by means of a juxtaposition in which a control finger and a piezoelectric actuator are arranged alongside one another in one and the same deflection plane.

The base section expediently has a base plate, from which two finger carriers projecting at a transverse distance from one another protrude, in each case with an intermediate shifter. tion of one of the solid joints of the control finger is pivotally mounted. In this way, a free space can be obtained between the two solid joints, which advantageously supports the desired independence between the pivoting movements of the two control fingers.

The piezo valve is expediently equipped with an electronic control device for the piezoelectric actuators. For this purpose, a control head arranged on the valve housing can be present, which contains the electronic control device. If required, this control device can be designed so that a controlled operation of the piezo valve is possible. In particular, the control device may be designed to take into account measured values obtained by a pressure sensor and / or a flow sensor when controlling the piezo actuators. This at least one pressure sensor and / or flow sensor is preferably an immediate component of the piezo valve.

The invention will be explained in more detail with reference to the accompanying drawings. In this show:

1 shows an advantageous embodiment of the piezoelectric valve according to the invention in a perspective external view,

FIG. 2 shows an exploded view of a valve unit of the piezo valve which is responsible for the fluid control;

3 shows the piezo valve of Figure 1 in longitudinal section according to

Section line III-III, wherein the area of a solid-state joint is shown enlarged in addition, Figure 4 shows a cross section through the valve unit of

Piezo valve according to section line IV-IV of Figure 3 in the closed position of both closure sections,

Figure 5 is a sectional view similar to Figure 4, wherein the one closure portion an open position and the other closure portion the

Closed position,

FIG. 6 shows the arrangement from FIG. 5 with reversed positions of the closure sections, FIG. 7 shows an individual view of the control unit movably accommodated in the valve housing in a side view with a viewing direction according to arrow VII from FIG.

Figure 8 shows a top view of the control unit with

Viewing direction according to arrow VIII of Figure 7,

FIG. 9 shows a perspective individual representation of the control unit,

FIG. 10 shows a section of the piezo valve in the deactivated state

FIG. 11 shows a representation comparable to FIG. 10, wherein one piezoactuator is activated and the other piezoactuator is deactivated,

FIG. 12 shows the arrangement of FIG. 11 with reversed activation and deactivation of the two piezoactuators, Figure 13 is a side view of the control unit in a state according to Figure 11 and

FIG. 14 shows a side view of the control unit in a state according to FIG. 12.

Denoted in its entirety by reference numeral 1

Piezo valve contains a valve unit 2 with a valve housing 3. In the interior of the valve housing 3, a valve chamber 4 is formed.

By way of example, the valve housing 3 is block-shaped or cuboid. It expediently contains a lower part 5 with a bottom wall 5a and a circumferential, upwardly projecting side wall 5b. On the bottom wall 5 a opposite edge of the side wall 5 b, a housing cover 6 is placed, in particular with the interposition of a circumferential seal. 7

The valve chamber 4 is located mainly in the lower part 5 and is closed at the top by the housing cover 6.

The valve chamber 4 and in particular also the valve housing 3 have an elongate shape with a longitudinal axis 8. A vertical axis 12 extends at right angles to the longitudinal axis 8 and extends perpendicular to the bottom wall 5 a by way of example. A perpendicular to the longitudinal axis 8 and the vertical axis 12 axis is hereinafter referred to as the transverse axis 13.

In the valve chamber 4 open on the inner surface of the bottom wall 5a, a first and second valve channel 14a, 14b. Their mouths are arranged in the direction of the transverse axis 13 at a distance from each other and framed by a first and second valve seat, which is fixedly arranged on the valve housing 3. In Axial direction of the longitudinal axis 8 are the two valve seats 15a, 15b expediently at the same height.

The two valve channels 14a, 14b each open to an outer surface of the valve housing 3. In the exemplary embodiment, the first valve channel 14a forms a feed channel which can be connected to a pressure source P, while the second valve channel 14b forms a venting channel which can be connected to the atmosphere R. A connection unit 16 arranged at the outer mouth of the first valve channel 14a allows the connection of a fluid line leading to a pressure source (not shown). At the outer mouth of the second valve channel 14b, a muffler 17 is connected by way of example.

A third valve channel 14c opens on the one hand also in the valve chamber 4 and on the other hand to an outer surface of the valve housing 3. It is used in the embodiment as connectable with a consumer A working channel. At the outer mouth of the third valve channel 14c, a connection unit 16 is likewise arranged, with which a fluid line leading to the consumer to be controlled can be detachably connected.

While the first and second valve channels 14a, 14b are controllable by a control unit 23 arranged in the valve chamber 4, this does not apply to the third valve channel 14c. This flows constantly unaffected by the control unit 23 in the valve chamber 4 and therefore does not need in the region of its inner mouth and no valve seat.

The valve chamber 4 has a longitudinal extent along the longitudinal axis 8 and in this case has two opposite end regions, which are to be referred to below as the front and rear end region. The two valve Seats 15a, 15b are exemplarily placed in the front end region of the valve chamber 4.

In the rear end region of the valve chamber 4, a first bearing component 22a of a pivot bearing device 22 is arranged on the bottom wall 5a. It is designed as in the axial direction of the transverse axis 13 extending and upwardly projecting into the valve chamber 4 projection which tapers like a blade and therefore hereinafter also referred to as a bearing blade.

Inside the Ventilkamer 4, a movable control unit 23 is arranged. The same is shown separately again in FIGS. 7 to 9, 13 and 14. It is an assembly which comprises, as essential components, a control body 24 which is designed in particular in one piece and two first and second piezoactuators 25a, 25b designed as stacking transformers.

The control unit 23 extends in the axial direction of

Longitudinal axis 8 and thereby both on the first bearing component 22a and the two valve seats 15a, 15b away.

The control body 24, which consists in particular of metal and in this case preferably of steel, has a second bearing component 22b at its rear end section extending in addition to the first bearing component 22a

Swivel bearing device 22. This is a longitudinal groove formed on the underside of the control body 24 facing the bottom wall 5a and extending in the transverse direction 13, which is also referred to below as a bearing groove. With this bearing groove 22b, the control body 24 sits on the bearing blade 22a, so that the same engages in the bearing groove 22b. Here is a line contact, the an extending in the axial direction of the transverse axis 13

Pivot axis 26 defined by which the control body 24 relative to the valve housing 3 according to double arrow 27 is pivotable.

In principle, the pivot bearing device 22 could also be generated in other ways, for example, by bores in the valve housing 3 and in the control body 24, are inserted into the bearing pin. The realized in the embodiment pivot bearing device 22, the cutting edge

can be labeled, but can be easily manufactured and allows a very simple pivoting mounting of the control body 24 by this is placed only on the first bearing component 22a.

The arrangement of bearing blade 22a and bearing groove 22b could also be reversed.

The control body 24 has a base section 28 and two first and second control fingers 31a, 31b which are arranged alongside one another and project away from the base section 28 at a lateral distance from one another in the same direction. While the base portion 28 forms the rear end portion of the control body 24, the two control fingers 31 a, 31 b belong to the front end portion of the control body 24.

The second bearing component 22 b is disposed on the base portion 28. Consequently, the pivotal mounting of the control body 24 takes place at this base portion 28.

While the first control finger 31a projects beyond the first valve seat 15a with a longitudinal section designated as the first closure section 32a, the second control finger 31b projects beyond the second valve seat 15b with a longitudinal section designated as a second closure section 32b. The two closure sections 32a, 32b are expediently formed by the base sections 28 axially opposite end portions of the control fingers 31a, 31b.

Each closure section 32a, 32b has, at its side facing the associated valve seat 15a, 15b, a closure surface 33 in the region opposite this valve seat 15a, 15b, which sealing surface can be brought into abutment against the opposite valve seat 15a, 15b in order to contact the relevant valve seat 15a 15b valve port 14a or 14b shut off. The closure surface 33 may be formed directly by an outer surface of the associated control finger 31a, 31b, but is expediently located on a sealing element 34 which is in particular made of material with rubber-elastic properties and which is fixed to the control finger 31a, 31b.

Between the first control finger 31a and the base portion 28, a first solid-state joint 35a is interposed, between the second control finger 31b and the base portion 28, a second solid-state joint 35b. The solid joints 35a, 35b are integral and in particular integral parts of the control body 24 and cause mutually independent hinged connections between each control finger 31a, 31b and the base portion 28. The hinge axes 36 of both solid joints 35a, 35b are parallel to the pivot axis 26. Each control finger 31a, 31b and the base portion 28 are pivotable about the respective associated hinge axis 36 relative to each other. However, this only with a corresponding expenditure of force, since the solid-state joints 35a, 35b have a relatively high torque stiffness.

The enlarged detail in FIG. 3 makes it clear that each solid-body joint 35 a, 35 b is expediently of one type bendable material web 37 of the control body 24 is formed, which extends in the axial direction of the longitudinal axis 8 and which engages at one end on one of the control fingers 31a, 31b and the other end on the base portion 28. Such a material web 37 can be realized, in particular, by two incisions 38 which are spaced apart from one another and which are introduced into the control body 24 from opposite sides. The stiffness of the solid-body joint 35a, 35b is determined here by the thickness of the material web 37 and the depth and width of the incisions 38.

In the advantageous embodiment of the control body 24 that can be seen from the drawing, the base section 28 includes a base plate 42 integrally formed therein which extends in a plane parallel to the pivot axis 26 and from the rear side, particularly in the region of the pivot axis 26, as a termination wall 43 designated projection protrudes in a direction perpendicular to the plane of extension of the base plate 42 first direction. In the exemplary embodiment, the first direction points away from the bottom wall 5a in the direction of the housing cover 6.

At the end wall 43 axially opposite front side of the base plate 42, two also in the first direction, and thus projecting upward in the exemplary embodiment, which are designated on the basis of their function as the first and second finger carrier 44a, 44b. The two finger carriers 44a, 44b are spaced apart in the axial direction of the transverse axis 13.

Each finger carrier 44a, 44b carries one of the two control fingers 31a, 31b with the interposition of a solid-state joint 35a, 35b. Their transverse distance corresponds expediently to that between the two finger carriers 44a, 44b. The First solid-state joint 35a is seated in the above-mentioned first direction, for example vertically, between the first finger carrier 44a and the rear end section of the first control finger 31a. The same arrangement applies to the second solid-state joint 35b with respect to the second finger carrier 44b and the second control finger 31b. The material web of each solid-state joint 35a, 35b is integrally connected at one end to one of the finger carriers 44a, 44b and at the other end to the rear end portion of one of the control fingers 31a, 31b.

The two control fingers 31a, 31b are preferably L-shaped. The longer L-leg 46 forms the associated closure portion 32a, 32b, while the shorter L-leg 47 forms the rear end portion of the control finger 31a, 31b and is connected at its end face to the respective subsequent solid-state joint 35a, 35b. Thus, the two longer L-legs 46 extend substantially axially, ie in the axial direction of the longitudinal axis 8, while the shorter L-legs 47 extend in the axial direction of the vertical axis 12 and thus also at right angles to the plane of extension of the base plate 42.

The in the opposite direction as the associated longer L-leg 46 facing outer surface of each shorter L-leg 47, which is hereinafter referred to as force introduction surface 48 is oriented backwards and the end wall 43 facing.

Together, the base plate 42, the end wall 43, the finger carriers 44a, 44b projecting in the same direction as the end wall 43, and the shorter L legs 47 of the control fingers 31a, 31b define a longitudinal recess 52 of the control body 24 which is adjacent to the bottom wall 5a opposite top and also in the axial direction of the transverse axis 13 oriented sites is open. The control body 24 thus has a U-shaped longitudinal section in this area. The recess 52 serves to receive the two piezoactuators 25a, 25b.

The two piezoactuators 25a, 25b each have a longitudinal extent with longitudinal axes 53a, 53b. They are aligned in the recess 52 so that their longitudinal axes 53a, 53b parallel to each other and in particular also parallel to the

Longitudinal axis 8 run. Each piezoactuator 25a, 25b has an axially oriented rear end face 54, with which it is supported directly or indirectly on the inside on the end wall 43, and also an oppositely and exemplarily forward facing front end face 55, with which he

Force introduction surface 48 of each one of the two control fingers 31a, 31b is supported.

While the support with respect to the end wall 43 can be made in particular over a large area, both are based

Piezoactuators 25a, 25b in the region of the force introduction surface 48 expediently only selectively or linearly in a limited area, which is designated as force introduction point 56 and which is defined in particular by a protruding into the recess 52 hump-like projection on the force introduction surface 48. This is particularly well in the enlarged section of FIG. 3

In principle, the piezo actuators 25a, 25b could be supported with their rear end surfaces 54 directly on the end wall 43. Appropriately, however, is the embodiment realized in the embodiment, in which only indirect or indirect support with the interposition of an adjusting screw 57 takes place, which is screwed into a the end wall 43 passing through threaded hole and slightly from the rear protrudes into the recess 52. With the help of the adjusting screws 57, the axial bias of the piezo actuators 25a, 25b set.

At each piezoelectric actuator 25a, 25b, the electrical actuation serving-serving contact means 58 are arranged. A preferably variable drive voltage can be applied to them for preferably stepless activation of each piezoactuator 25a, 25b. The two piezo actuators 25a, 25b are in particular actuatable independently of each other.

In the deactivated state of both piezoelectric actuators 25a, 25b, that is to say when no drive voltage is applied to any of the piezoactuators 25a, 25b, the control body 24 adopts a basic position which can be seen, for example, from FIGS. 3, 4, 7 and 10. Here, the two control fingers and in particular their closure portions 32a, 32b extend parallel to each other and in particular also parallel to the longitudinal axis 8. In this basic position, both closure portions 32a, 32b are under bias and shut off the associated valve channel 14a, 14b at the respectively associated valve seat 15a, 15b at. The two valve seats 15a, 15b are located on the same longitudinal side of the control body 24, for example below this. The pivot bearing device 22 is arranged on the same longitudinal side of the control body 24 as the valve seats 15a, 15b.

In favor of a flat design of the control unit 23, the control fingers 31a, 31b project away from the recess 52 and from the base section 28, respectively. This results in particular a pertinent arrangement, that in each case a control finger 31a, 31b and a piezoelectric actuator 25a, 25b are arranged axially in succession. In an alternative embodiment, not shown, the control fingers 31a, 31b are turned backwards from the finger carriers 44a, 44b and extend over the fingers

Piezoactuators 25a, 25b away. The piezo valve 1 builds shorter in this case, but at the same time a little higher.

The first control finger 31a extends in a first deflection plane 62a, the second control finger 31b extends in a second deflection plane 62b parallel thereto. Both Auslenkebenen 62 a, 62 b extend at right angles to the pivot axis 26 of the pivot bearing device 22nd

The piezoactuators 25a, 25b are preferably arranged such that the longitudinal axis 53a of the first piezoelectric actuator 25a extends in the first deflection plane 62a and the longitudinal axis 53b of the second piezoelectric actuator 25b in the second deflection plane 62b. In the deactivated state of the two piezoactuators 25a, 25b, their longitudinal axes 53a, 53b expediently run parallel to the longitudinal axes of the preferably rod-shaped closure sections 32a, 32b.

The simultaneous abutment of both closure portions 32a, 32b at their associated valve seats 15a, 15b in the basic position, is caused by spring means 63, which are effective between the control body 24 and the valve housing 3. For the sake of clarity, these spring means 63 are shown in Figures 10 to 12 as a single helical compression springs - to which it may in principle also act in practice -, but they are expediently realized in the form of at least one and preferably exactly one leaf spring consisting of figures 2 and 3 can be seen.

The spring means 63 constantly act on both control fingers 31a, 31b in the direction of one of the opposing valves. tilsitz 15a, 15b adjacent closed position. In the process, they act individually on each control finger 31a 31b in the region of the closure sections 32a, 32b. The force introduction point of the spring means 63 is in this case in particular at the axial height of the closure surfaces 33.

Preferably, the spring means 63 are formed so that they also act on the base portion and constantly press with its second bearing component 22b to the first bearing component 22a. Thus, the spring means 63 serve to bias the control body 24 on the one hand against the two valve seats 15a, 15b and on the other hand in the region of designed as a knife-edge bearing pivot bearing device 22nd

In one embodiment as a leaf spring 63a, the spring means 63 may have a support portion 64 which is supported on the inner surface of the housing cover 6 facing the valve chamber 4 and have four spring arms 65 which project away from this support portion 64, two of which point toward the upwardly facing end face of the end wall 43 press and two more on the closure surface 33 opposite top of each control finger 31a 31b.

In Figure 10 dashed lines at 63 'indicated that the simultaneous bias of the control body 24 against the valve seats 15a 15b and against the first bearing component 22a could also be realized by centrally acting spring means 63 ⁴ , which act on the control body 24 in the solid state joints.

A preferred mode of operation of the piezo valve 1 is as follows: In the deactivated state of the two piezo actuators 25a, 25b, the control body 24 assumes the basic position, which is synonymous with the assumption of a closed position on the associated valve seat 15a, 15b closing position of both closure portions 32a, 32b.

In order to lift the first closure portion 32a from the first valve seat 15a, so that a fluid connection between the first valve channel 14a and the third valve channel 14c is established through the valve chamber 4, an electrical activation of the second piezoelectric actuator 25b takes place. This operating state of the activated second piezoelectric actuator 25b can be seen in FIGS. 5, 11 and 13. The first piezoelectric actuator 25a remains deactivated.

When activated, the second piezoactuator 25b designed as a stack translator experiences an extension due to the so-called reverse piezoelectric effect, with the result that it introduces a relatively high first actuating force Fi into the second control finger 31b at the force introduction point 56. Due to the fact that the force introduction point 56 of the first actuating force Fi is arranged at a first distance Li from the associated second solid-state joint 35b, a torque, which tends to act on the second control finger 31b relative to the base portion 28, acts on the second control finger 31b according to arrow 66 to pivot toward the second valve seat 15b.

This has the consequence that the second control finger 31b is pressed in the region of its closure surface 33 with a second actuating force F2 to the second valve seat 15b. The force introduction point of the second actuating force F2 is arranged at a second distance L2 to the second solid-state joint 35b. Due to the fact that the second valve seat 15b can not yield, it acts as an abutment for the second control finger 31b in the region of the closure surface 33.

In addition, since the control body 24 is also supported on the pivot bearing device 22 in the same direction as the second valve seat 15b, but intervening therebetween and not secured to the valve housing 3, deflection of the control body in the region of the second solid-state joint 35b occurs in the above-mentioned first one Direction, in the exemplary embodiment so directed upward away from the bottom wall 5a, instead. In this bending on the one hand, the base portion 28 is pivoted about the pivot axis 26 and there is also a slight pivoting of the second control finger 31b to the second valve seat 15b, but the deflection is so small that the closed position is not canceled. A secure closed position can be promoted in particular by the fact that an elastically yielding sealing element 34 is used, which compensates the pivoting angle while maintaining the sealing contact.

After the base portion 28 is pivoted upward in bending of the control body 24 in the region of its second solid-body joint 35b of the bottom wall 5a, a corresponding pivoting of the likewise arranged on the base portion 28 first solid-state joint 35a automatically takes place. As a result, the first control finger 31a arranged on the first solid-state joint 35a, since it is not blocked in this direction, is entrained and lifts off from its associated first valve seat 15a. As a result, the connection of the first valve channel 14 a to the valve chamber 4 is released. If the second piezoelectric actuator 25b is deactivated again in the sequence, the control body 24 returns to the basic position due to the restoring forces inherent in the elastic second solid-body joint 35b, and again both the first and the second valve channels 14a, 14b are shut off.

If the second valve channel 14b is now to be connected to the valve chamber 4 and over the latter to the third valve channel 14c, this is done by activating the first valve

Piezoactuator 25a, wherein the second piezoelectric actuator 25b remains deactivated. This state is shown in FIGS. 6, 12 and 14. The same motion sequences take place here with reversed rollers of the control fingers and solid-body joints, which were described above upon activation of the second piezoactuator 25b, wherein now the first control finger 31a according to arrow 66 to the first Valve seat 15a is pressed so that the taking place in the region of the first solid-state joint 35a

Bending of the control body 24 entails entrainment of the second control finger 31b, so that this according to. Arrow 67 is removed from its associated second valve seat 15b.

The intensity of the deflection of the two control fingers 31a, 31b, which can also be referred to as a stroke, and thus their distance to the assigned valve seat, which position is in the open position lifted from the associated valve seat 15a, 15b, can expediently be set variably. Since the distance of a closure surface 33 from the valve seat 15 a, 15 b the the

In this way, the flow, ie the flow rate, can be regulated by means of the flow cross-section provided by the fluid flowing through. Thus, the piezo valve can be used as a proportional valve with steady operating behavior. The variable deflection is very easy simply achieve that the two piezo actuators 25a, 25b are variably activated with different levels of drive voltages.

The piezo valve can thus be used in particular as a 3/3 -way proportional valve, wherein it either simultaneously blocks the first and the second valve channel 14a, 14b or alternatively connects with the first or second valve channel 14a, 14b and at the same time separated from the other of these two said first and second valve channels 14a, 14b. In each case, a plurality of different distances between each closure section 32a, 32b and the associated valve seat 15a, 15b are continuously adjustable.

Due to their configuration as stack translators, the piezo actuators 25a, 25b are able to generate very high compressive forces.

The stack translators expediently consist of a plurality of thin ceramic disks, for example with thicknesses between 0.3 and 1 mm, in which metal electrodes for the supply of the drive voltage are located. The individual disks are stacked and glued together in pairs with opposite polarization direction. This results in an electrically parallel and mechanically connected in series stack of piezoelectric disks whose thickness increases with electrical control, the Gesamthafte change in length of the

Piezo stack resulting from the sum of the change in thickness of the individual elements.

Despite the stack construction, the maximum change in length of the piezo actuators 25a, 25b is relatively small. This is however through a more than compensated for a stroke ratio obtained in connection with the articulated control fingers 31a, 31b. It is thus possible to realize relatively large deflection strokes of the control fingers 31a, 31b in the region of the valve seats 15a, 15b. Overall, it is thus possible to control a wide range of flow rates or pressures with one and the same piezo valve.

The mentioned stroke ratio results in particular from the fact that the second distance L2 between each solid-body joint 35a, 35b and the closure surface 33 of the control finger 31a, 31b arranged thereon is greater than the distance between the said solid-state joint 35a, 35b and that of the associated piezoactuator 25a, 25b acted force application point 56 of the respective control finger 31a, 31b.

In the exemplary embodiment, an approximately twenty-fold stroke ratio is realized via the two control fingers 31a, 31b, each of which is pivotably mounted via a solid-body joint.

In the exemplary arrangement, the force introduction point 56 is spaced in a different direction from the solid-state joint 35a, 35b as the closure surface 33. The first distance Li is measured in particular in the axial direction of the vertical axis 12, while the second distance L2 in the axis direction of the longitudinal axis 8 measures.

The piezo valve 1 is expediently equipped with an electronic control device 68, via which the two piezo actuators 25a, 25b can be electrically controlled. By way of example, the electronic control device 68 is realized by using at least one printed circuit board 71 equipped with electronic components. In addition to the valve unit 2, the piezo valve 1 can have an actuation head 72 attached to the valve housing 3, in the interior of which the electronic control device 68 is located, and which in particular lies on top of the valve body

Housing cover 6 is placed. The housing cover 6 may have apertures 73 through which the contact means 58 are passed, so that they lead into an inner space 74 of the Ansteuerkopfes 72, in which the electronic control device 68 is housed and in which they are contacted with this electronic control device 68.

An externally accessible electromechanical interface 75 allows electrical communication of the internal electronic control device 68 with an external control electronics, not shown.

In the exemplary embodiment, the internal electronic control device 68 is assigned a pressure sensor 76 which detects the pressure prevailing in the valve chamber 4 and consequently the pressure prevailing in the third valve channel 14c so that it can be utilized in the electrical control of the piezoactuators 25a, 25b, in particular during controlled operation ,

It would also be possible to additionally or alternatively integrate a flow sensor, so that a pressure-controlled and / or flow-controlled operation of the piezo valve 1 is possible.

The piezo valve can be realized very inexpensively, because suitable stack translators are made available at low cost on the market by different manufacturers. Since the piezo valve covers a very high pressure range, it saves the provision of several, specially adapted for different pressure ranges valves, which in the Manufacturing promises a high cost saving. Due to the almost friction-free construction with solid-state joints, the valve design shows a very low hysteresis and thus enables very exact pressure and / or flow specifications. Since the control unit 24 and the piezo actuators 25a, 25b composed control unit 23 has a high rigidity, occur even at large pressure differences only small differences in lift. This results in a very good controllability of the valve. The construction realized in the exemplary embodiment is temperature-compensated and extremely insensitive to tolerances.

Claims

claims

1. Piezo valve, comprising a valve housing (3) in which a movable control unit (23) is arranged which has a control body (24) with a base section (28) and two control fingers (31a, 31b) projecting side by side from the base section (28) wherein the control body (24) at its base portion (28) relative to the valve housing (3) about a pivot axis (26) is pivotally mounted and the two control fingers (31a, 31b), each with a closure portion (32a, 32b) via one of two arranged on the valve housing (3) valve seats (15a, 15b) protrude, wherein the control unit (23) further comprises two each one of the control fingers (31a, 31b) associated piezoelectric actuators (25a, 25b), by their individual activation of the respective associated closure portion (32a, 32b) while the control body (24) is simultaneously deflectable against the valve seat (15a, 15b) opposite it, so that the base section (28) including the other control Fingers (31b, 31a) is pivoted about the pivot axis (26) and thereby the said other control finger (31b, 31a) associated closure portion (32b, 32a) is removed from its associated valve seat (15b, 15a), characterized in that each Control finger (31a, 31b) is connected via an integrated solid-state joint (35a, 35b) of the control body (24) to the base portion (28) and that the two piezoelectric actuators (25a, 25b) are formed by stacked transformers separate from the control body (24), each supported on one hand on one of the control fingers (31a, 31b) and on the other hand on the base portion (28) of the control body (24), so that by their selective activation of the respectively associated control fingers (31a, 31b) in the region of the solid-state joint (35a, 35b) with respect to the base portion (28) is pivotable.

2. Piezo valve according to claim 1, characterized in that the two valve seats (15a, 15b) in each case one in a valve chamber (4) opening first or second valve channel (14a, 14b) are assigned, wherein also also a third valve channel (14c ) into the valve chamber (4) in an uninfluenced manner by the control unit (23).

3. piezo valve according to claim 1 or 2, characterized in that it is designed as a proportional valve, wherein the two piezoelectric actuators (25a, 25b) are variably electrically activated such that continuously a plurality of different distances between each closure portion (32a, 32b) and the each associated valve seat (15a, 15b) is adjustable.

4. Piezoelectric valve according to one of claims 1 to 3, characterized in that at least one of the two solid joints (35a, 35b) of a flexible material web (37) is formed, which in one piece with the base portion (28) and on the other hand with the associated control finger (31a, 31b) is connected.

5. Piezoelectric valve according to one of claims 1 to 4, characterized in that the closure portion (32a, 32b) has an associated valve seat (15a, 15b) opposite closure surface (33), wherein the distance between the solid-state joint (35a, 35b) and the closure surface (33) is greater than the distance between the solid-body joint (35a, 35b) and that of the associated piezoelectric actuator (25a, 25b) acted upon force application point (56) of the control finger (31a, 31b).

6. Piezo valve according to one of claims 1 to 5, characterized in that the control finger (31 a, 31 b) is designed L-shaped, wherein the longer L-leg (46) forms the closure portion (32 a, 32 b) and the shorter L Leg (47) with the associated solid-state joint (35a, 35b) is connected, wherein the acted upon by the associated piezoelectric actuator (25a, 25b) force application point (56) of the control finger (31a, 31b) is located on the shorter leg L (47) and expediently at the outer surface of the shorter L-leg (47) opposite the longer L-leg (46).

7. Piezoelectric valve according to one of claims 1 to 6, characterized in that the piezoelectric actuators (25a, 25b) are accommodated together in a lateral recess (52) of the control body (24) on one side of the to the solid state joints (35a , 35b) adjoining rear end portions of the control fingers (31a, 31b) and on the opposite side of a terminal wall (43) of the base portion (28) is limited, wherein the piezoelectric actuators (25a, 25b) on the one hand at the rear end portions of the control fingers ( 31a, 31b) and on the other hand on the end wall (43).

8. Piezo valve according to one of claims 1 to 7, characterized in that the two control fingers (31a, 31b) in the deactivated state of the piezoelectric actuators (25a, 25b) extend parallel to each other and / or that the two valve seats (15a, 15b) the same longitudinal side of the control body (24) are arranged.

9. Piezo valve according to one of claims 1 to 8, characterized in that the pivot bearing of the control body (24) is realized by a cutting bearing, as a bearing component (22b) a bearing groove and as another bearing component (22a) engaging in the bearing groove bearing blade wherein the one bearing component (22b) on the base portion (28) of the control body (24) and the other bearing component (22a) on the valve housing (3) is arranged.

10. Piezo valve according to one of claims 1 to 9, characterized in that between the valve housing (3) and the control body (24) acting spring means (63, 63 *) are present, the two control fingers (31 a, 31 b) constantly in the direction act on a closed valve seat (15a, 15b) adjacent closed position, said spring means (63, 63 ') expediently either in the region of the closure portions (32a, 32b) or in the region of the solid state joints (35a, 35b) acting on the control body (24) ,

11. Piezo valve according to claim 10, characterized in that the spring means (63, 63 ^λ ) also act on the base portion and expediently press this on a valve housing (3) and serving for its pivot bearing bearing component (22 a).

12. Piezoelectric valve according to one of claims 1 to 13, characterized in that the two control fingers (31a, 31b) in mutually parallel, perpendicular to the pivot axis (26) of the pivotal mounting of the base portion (28) extending Auslenkebenen (62a, 62b) extend.

13. Piezo valve according to claim 12, characterized in that the piezo actuators (25a, 25b) with in each case one of the Auslenkebenen (62a, 62b) extending longitudinal axes (53a, 53b) are arranged, wherein expediently in each case a control finger (31a, 31b) and a piezoelectric actuator (25a, 25b) are arranged axially successively.

14. Piezo valve according to one of claims 1 to 13, characterized in that the base portion (28) has two transversely spaced finger carrier (44a, 44b), each with the interposition of one of the solid-state joints (35a, 35b) one of the control fingers ( 31a, 31b).

15. Piezo valve according to one of claims 1 to 14, characterized in that the control body (24) is a one-piece, suitably made of metal component.

16. Piezo valve according to one of claims 1 to 15, characterized in that on the valve housing (3) an electronic control device (68) for the piezo actuators (25a, 25b) receiving the drive head (72) is arranged.