Solenoid valve

The invention relates to a solenoid valve (100), which has a valve rod (141), an electromagnetic actuation device (131, 135, 139) for deflecting the valve rod (141) starting from a first switching position into a second switching position, and a support device (110, 210, 310, 410) for supporting the valve rod (141). The support device (110, 210, 310, 410) has a different form depending upon the deflection of the valve rod (141). The solenoid valve (100) further comprises a locking device (121, 122, 123, 125), which is designed to move a moveable holding element (121) into a locking position upon activation of the electromagnetic actuation device (131, 135, 139) in order to deflect the valve rod (141) into the second switching position, in which locking position the holding element (121) lies against the support device (110, 210, 310, 410), and is designed to move the holding element (121) away from the locking position upon deactivation of the electromagnetic actuation device (131, 135, 139).

BACKGROUND OF THE INVENTION

The invention relates to a solenoid valve, which has an electromagnetically actuated valve rod. The valve rod can be deflected starting from a first switching position into a second switching position.

Solenoid valves which can be electrically actuated are used, for example, for switching coolant circuits in cooling systems of motor vehicles. Such valves can assume stable switching positions in the respective end positions thereof (i.e. degenergized or energized), whereby “digital” switching operations can be achieved. Known solenoid valves have a deflectable valve rod, on which a ferromagnetic armature and (at least) one closing element in the form of a sealing cone are disposed. By energizing a field coil, the armature and an associated ferromagnetic opposite pole can be magnetized, whereby a force of attraction between said components and thereby a deflection of the valve rod starting from a first switching position into a second switching position can be brought about. The closing element disposed on the valve rod can thereby be moved into a valve seat or be removed from the same. With the aid of a return spring and/or as a result of the hydraulic pressure of a coolant, the valve rod can again return back into a first starting position when power is switched off to the solenoid valve. Valves working according to this principle, which are available as a normally open valve or as a switching valve, are described in the German patent specification DE 197 54 257 A1, the European patent specification EP 0 653 990 B1 and the German patent specification DE 197 53 575 A1.

A disadvantage of conventional solenoid valves is a relatively high, permanent current consumption in the energized switching position. The use of a cut-off valve in a vehicle cooling system can, for example, require a closing force in the range of20N in order to hold the valve closed against the force of the return spring and against the hydraulic pressure. In the case of an on-board voltage of 12V, this can be associated with a permanent current consumption in the range of 1 A. Because no mechanical work is performed in the closed valve state, the electrical power in the field coil of the valve is completely converted into heat. This power loss makes it difficult to use such a cut-off valve in modern, efficiency-optimized vehicles. The dimensioning of the coil is also substantially determined by the aforementioned thermal boundary condition.

In contrast, solenoid valves have the advantage of behaving reliably in the event of a fault (fail-safe function) because the valves independently switch into a stable, secure switching position (for example: open) when a loss of the electrical power supply occurs (for example as a result of contact interruption, voltage drop, cable breakage, plug separation, etc.). In the case of valves which are designed differently and in which there is no electrical power consumption in stable switching positions, said fail-safe function cannot be realized to date or can only be implemented with the aid of auxiliary mechanisms (which in turn are associated with a high permanent current consumption). For that reason, solenoid valves continue to be widely used in motor vehicle cooling systems despite the high power electrical power loss associated with the use thereof

SUMMARY OF THE INVENTION

The aim of the invention is to specify an improved solenoid valve, with which a high permanent current consumption can be prevented in a switching position while fully implementing a fail-safe function.

According to the invention, a solenoid valve is proposed which has a valve rod, an electromagnetic actuation device for deflecting the valve rod starting from a first switching position into a second switching position, and a support device for supporting the valve rod. The support device has a different form depending upon the deflection of the valve rod. The solenoid valve further comprises a locking device, which is designed to move a moveable holding element into a locking position upon activation of the electromagnetic actuation device in order to deflect the valve rod into the second switching position, in which locking position the holding element lies against the support device; and said locking device is designed to move the holding element away from the locking position upon deactivation of the electromagnetic actuation device.

In the solenoid valve, the valve rod can be deflected starting from the first into the second switching position by activating the electromagnetic actuation device. The deflection of the valve rod, which can occur against a restoring force (for example produced by a return spring and/or as a result of a hydraulic pressure), is associated with a change in the form of the support device. The activation of the electromagnetic actuation device further results in the locking device moving the holding element into the locking position so that the holding element rests against the support device. In so doing, the holding element can counteract an (oppositely directed) change in the form of the support device and thereby lend said support device an enhanced stability or strength. In this state, the valve rod that is supported by the support device can be reliably held in the second switching position. The locking of the support device and thereby the valve rod, which was implemented in this manner, makes it possible to largely reduce an electrical energy supply to the solenoid valve after the second switching position has been reached, said energy supply being used to activate the actuation device and thus to deflect the valve rod. A relatively small (respectively minimum) electrical energy supply can ensure that the holding element remains in the locking position.

The solenoid valve furthermore exhibits a reliable behavior in the event of a fault. If the reduced electrical energy supply used to retain the holding element in the locking position is cut off (or undershot) or, respectively, the electromagnetic actuation device is deactivated, the holding element is moved away from the locking position. As a result, the lock of the support element is released whereby the valve rod can again return independently or as a result of the restoring force into the first switching position.

In a preferred embodiment, the support device is designed to convert a holding force acting on the support device into a supporting force acting on the valve rod. The ratio of holding force to supporting force is nonlinearly dependent on the form of the support device and therefore on the deflection of the valve rod. The locking device is designed to transfer the holding force to the support element (only) by the holding element being moved into the locking position. In this state, the holding force transferred by the holding element to the support device is less than the supporting force acting on the valve rod. In this embodiment, the nonlinear behavior of the support device is used for locking said support device (and therefore the valve rod) using a relatively small holding force between the holding element and the support device. As a result, the holding force can be converted into a substantially larger supporting force between the support device and the valve rod. Similarly, a large application of force by the valve rod on the support device (=counteracting force with respect to supporting force) results in only a small application of force by the support element on the holding element (=counteracting force with respect to holding force). Thus, it is possible to again move the holding element away from the locking position in a reliable manner, in particular with relatively little expenditure of force.

The support device can particularly be disposed between the valve rod and a portion of a housing of the solenoid valve; thus enabling the support device to be supported at the housing. In addition, provision can be made for the longitudinal dimension of the support device to increase in size and in contrast for the lateral dimension to decrease in size when the valve rod is deflected from the first into the second switching position. In so doing, provision can be made for the decrease in size of the lateral dimension to initially enable the holding element to move into the locking position thereof. The holding element resting in this position against the support device can serve to counteract a lateral extension of said support device and thereby a reduction in the longitudinal dimension of the support device.

In a further preferred embodiment, the support device is designed as a toggle lever mechanism. Such an embodiment offers the possibility for implementing the nonlinear behavior of holding force in relation to the supporting force described above in a relatively simple manner.

In this respect, provision is made according to a further preferred embodiment for the support device to comprise a spring sleeve which includes two end sections and connecting webs that connect the end sections. The spring sleeve can, for example, be formed from a metallic material, for example spring steel. In such a relatively simple and cost effective embodiment of a resilient toggle lever mechanism, each of the connecting webs of the spring sleeve can be understood as an arrangement of two limbs of a toggle lever. Corresponding “pivot points” can be situated on the end sections and in the region of each connecting web. As a result, the spring sleeve can be pressed together axially in the first switching position of the valve rod and be extended radially outwards. When the valve rod is deflected into the second switching position, the spring sleeve can independently assume a shape which is substantially axially elongated and only slightly extended outwards and therefore have a smaller lateral dimension with respect to the first switching position. A high degree of rigidity can be provided to the spring sleeve via the holding element that rests against said spring sleeve (only) in this state, whereby said sleeve can be prevented from being axially compressed. The holding force of the holding element can be converted via the spring sleeve into a relatively large supporting force that acts on the valve rod.

Instead of being embodied as a spring sleeve, a toggle lever mechanism can also be implemented in another manner. A possible example is a support device having two end sections, wherein the two end sections are connected via two adjacent limbs at two or more locations. Pivot points, for example in the form of integral hinges, can be provided between the adjacent limbs and respectively between a limb and an end section. In order for such a support device to independently distend in the axial direction, the support device can furthermore be designed to include an additional spring element between the two end sections.

In addition, other embodiments of a support device are also conceivable, in which a nonlinear behavior is likewise present. In this regard, provision is made in a further preferred embodiment for the support device to comprise two support elements that are connected via a hinge and can move or pivot relative to one another. A spring element is disposed between the support elements in order to position said support elements, when the valve rod is deflected from the first into the second switching position, such that the holding element can be moved into the locking position. Such a support device is likewise suitable for converting the holding force of the holding element into a relatively large supporting force acting on the valve rod.

This applies in a corresponding manner to a further preferred embodiment, according to which the support device comprises two support elements that can be displaced relative to one another. One of the support elements is connected via a hinge to the valve rod. The other of the two support elements is connected via a hinge to a fastening section provided on the solenoid valve. In addition, spring elements are disposed on the support elements in order to position said support elements upon deflecting the valve rod from the first into the second switching position such that the holding element can be moved into the locking position.

The electromagnetic actuation device preferably comprises a solenoid armature connected to the valve rod, a yoke and a field coil. A return spring is disposed between the solenoid armature and the yoke. The solenoid armature and the yoke can be magnetized via the field coil; thus enabling an attraction to be produced between the solenoid armature and the yoke against the restoring force of the return spring and in so doing the valve rod to be deflected from the first into the second switching position.

In a further preferred embodiment, the locking device comprises a spring element for moving the holding element into the locking position, an armature element that can be moved with respect to the valve rod and a further return spring. The movable armature element is supported at the holding element that is used for locking the support device. The further return spring is disposed between the movable armature element and the solenoid armature disposed on the valve rod. The movable armature element can (likewise) be magnetized via the field coil; thus enabling an attraction to be produced between the movable armature element and the solenoid armature against the restoring force of the further return spring and thereby the holding element to be moved via the associated spring element into the locking position. Such an embodiment of the locking device makes it possible to move the holding element reliably into the locking position at the support device upon activation of the electromagnetic actuation device (i.e. when current is supplied to the field coil). Upon deactivation of the actuation device, the holding element can again reliably be moved away from the locking position. The movable armature element and the solenoid armature are thereby pressed apart by means of the action of the further return spring, whereby the movable armature element can press the holding element away from the locking position thereof.

The locking of the support device and therefore the valve rod enables an energy supply to the solenoid valve or, respectively, a current supply to the field coil to be greatly reduced after the valve rod has been deflected into the second switching position. The attraction between the movable armature element and the solenoid armature disposed on the valve rod can be maintained by means of the reduced or minimal energization of the field coil; thus enabling the holding element to remain in the locking position. The small energization of the field coil further allows said coil to be dimensioned substantially smaller in relation to a conventional solenoid valve.

The previously described support between the movable armature element and the holding element is preferably implemented via a movable sleeve. In addition, the holding element is preferably designed in the shape of an annular disc. In one such embodiment, the holding element can reliably enclose the support device in the locking position.

The solenoid valve can, for example, be a changeover valve. In so doing, the valve can have two closing elements, in particular in the form of sealing cones, which are rotated relative to one another through 180 degrees, at different positions on the valve rod. In the first switching position, one of the closing elements can thereby rest against an associated valve seat of the solenoid valve and close the same; whereas a further valve seat is not closed. By the valve rod being deflected into the second switching position, the previously closed valve seat can be opened and the further valve seat can be closed by the other of the two closing elements, a changeover function thus being implemented.

The solenoid valve can furthermore be designed in the form of a cut-off valve. In so doing, a single closing element is provided on the valve rod. An embodiment that is preferred in this regard includes the fact that the support device is disposed at one end of the valve rod. The valve rod has a closing element at an opposite end, which closing element is movable and is resiliently disposed on the valve rod with the aid of a spring element. Component tolerances can be compensated by means of such a resilient arrangement of the closing element which can interact with a corresponding valve seat of the valve.

According to the invention, a solenoid valve is further proposed which comprises an electromagnetically actuated valve rod. The valve rod can be deflected starting from a first switching position into a second switching position. The solenoid valve further comprises locking means, via which a holding force can be converted into a supporting force that acts on the valve rod. The ratio of holding force to supporting force is nonlinearly dependent on the deflection of the valve rod. The locking means are designed to provide the holding force (only) in one state, in which the valve rod is located in the second switching position, and to convert said holding force into the supporting force acting on the valve rod. In so doing, the holding force provided by the locking means is smaller than the supporting force acting on the valve rod.

With the aid of the locking means, the valve rod can be locked in the second switching position and thereby held reliably in said position. The lock can thus be implemented with a relatively small holding force, which can be converted into a (substantially) larger supporting force acting on the valve rod due to the nonlinear behavior. The lock enables an energy supply to the solenoid valve, which energy supply is used for deflecting the valve rod, to be largely reduced after the second switching position has been achieved. Essentially only the maintenance of the lock via the locking means can be associated with the reduced (or a minimal) electrical energy supply. At the same time, a secure function in the case of a fault can be provided. To this end, provision can be made, in the event of the energy supply being interrupted (or not fully met), for the locking means to no longer provide a holding force (an thus no longer a sufficient supporting force), whereby the valve rod can again independently or as a result of the influence of a restoring force return back to the first switching position.

The embodiments specified above can be used in an appropriate manner for the solenoid valve comprising the locking means. In particular, the locking means can be implemented in the form of a support device and in the form of a locking device comprising a holding element.

The advantageous embodiments of and modifications to the invention, which are explained above and/or reflected in the dependent claims, can be used individually or else in any desired combination with one another—except, for example in cases of unambiguous dependencies or incompatible alternatives.

DETAILED DESCRIPTION

FIG. 1shows a schematic side view of a solenoid valve100that can be electrically actuated in an open state. The valve100, which is embodied as a cutoff-valve and can particularly be used in a coolant circuit of a motor vehicle, comprises two housing parts160,180. The housing parts160,180, which are also referred to below as pole pot or pole housing160and as valve housing180, are connected to one another via a mounting plate170that is disposed between the same.

The valve housing180, which is designed for the through-flow of a medium or, respectively, a coolant, encloses an internal space and has two asymmetrically disposed ports181,182. The coolant delivered by means of a pump can be supplied to the valve housing180via the lower port181inFIG. 1and can be discharged via the lateral port182(not depicted).

In the internal space, the valve housing180comprises a valve seat155and a closing element which is in the form of a sealing cone145and interacts with the valve seat155. The valve seat155configured as a sealing ring can be formed from an elastomer material. A spacer sleeve185is disposed in the valve housing180for fixing the valve seat155. With the help of said sleeve, the valve seat155is braced against a stop of the valve housing180which is located in the region of the lower port181. The spacer sleeve185has an opening187which is adapted to the lateral port182. As is further indicated inFIG. 1, a sealing collar175is provided on the underside of the mounting plate170, said collar lying on the spacer sleeve185and pressing said spacer sleeve185towards the valve seat155.

The sealing cone145is disposed at a lower end of a displaceably mounted valve rod141. The valve rod141can be deflected starting from the first switching position (initial position or “rest position”), which is shown inFIG. 1and in which the sealing cone145and the valve seat155are spaced apart from one another, into a second switching position (seeFIG. 2). This operation is carried out electromagnetically. In the second switching position, the sealing cone145rests against the valve seat155, whereby the valve100is closed and a volume flow is no longer possible between the ports181,182. Starting from the second switching position, the lift rod or valve rod141can again be put back into the first switching position.

As is further depicted inFIG. 1, the sealing cone145has a recess in which an end section of the valve rod141is accommodated. A spring element147is further disposed within the recess between the valve rod141and an opposing base area of the recess. As a result, the sealing cone145is displaceably and resiliently disposed on the valve rod141in the axial direction (i.e. with respect to a longitudinal axis of the valve rod141), whereby component tolerances can be compensated. The spring element147can, for example, be designed as a coil spring as indicated inFIG. 1or alternatively as a leaf spring.

The deflection of the valve rod141from the first into the second switching position and the return or reset thereof into the second switching position is brought about with the aid of components disposed in the pole housing160. The valve rod141is therefore fed through corresponding openings in the sealing collar175and the mounting plate170into the interior of the pole housing160. In order to seal the feed through, the sealing collar175can be embodied as a sealing bushing in the region of the valve rod141or can comprise such a bushing (not depicted).

The deflection of the valve rod141from the first into the second switching position is carried out by an electromagnetic actuation device, which comprises a solenoid armature135connected to the valve rod141, a yoke131(opposite pole) disposed at or fastened to the mounting plate170and a field coil139enclosing said components131,135. The yoke131and the solenoid armature135are formed from ferromagnetic material and have a substantially (hollow) cylindrical shape. The valve rod141is thereby fed in a central position thereof through the yoke131serving as a guide sleeve, and the solenoid armature135is fastened peripherally to the valve rod141. The joke131further has a cone-shaped recess on an upper side. The solenoid armature135has a conical section on an underside, said conical section corresponding in the contour thereof substantially to the contour of the cone-shaped section of the yoke131. A return spring137is further disposed in this region between the joke131and the solenoid armature135, which return spring pushes said two components131,135apart and can thereby effect an opening of the valve100or a holding of the same in the first or open switching position. The return spring137can, for example, be designed as a coil spring as is indicated inFIG. 1.

In order to activate the actuation device, current is supplied to the field coil139. In so doing a magnetic field can be generated, whereby the yoke131and the solenoid armature135are magnetized and an electromagnetic attractive force can be induced between said components131,135. In this way, the solenoid armature135disposed on the valve rod141can be pulled in the direction of the yoke131, and the valve rod141can thereby be displaced into the second switching position shown inFIG. 2, in which the sealing cone145rests against the valve seat155. The electromagnetic force acts against a restoring force which is induced by the return spring137as well as (if applicable) by the hydraulic pressure of a medium or coolant acting on the port181on the underside. In the closed valve state, a residual distance between the solenoid armature135and the yoke131can be present as depicted inFIG. 2, whereby component tolerances can be compensated. Provided the field coil139is deenergized or switched off, the valve rod141can again return to the first switching position shown inFIG. 1, in which the valve100is open, due to the influence of the restoring force (and the deactivation of a locking function as will be described further below).

In the case of a conventionally constructed solenoid valve, the maintenance of the closed state (against the restoring force) requires a relatively large, permanent current supply to the respective field coil. Because no mechanical work is performed in said closed state, the electrical power consumed by the coil is completely converted into heat, which is consequently associated with a high power loss. A conventional solenoid valve has further a design that is predetermined by this thermal boundary condition, in particular having relatively large dimensions of the associated field coil. The valve100shown inFIGS. 1 to 3is in contrast designed having a support device for supporting the valve rod141and having a locking device for locking the support device in the closed (energized) switching position, whereby a large, permanent current consumption can be prevented.

In the case of the valve100, the support device is designed as a toggle lever mechanism, which is implemented in the form of a spring sleeve110as depicted inFIGS. 1 to 3. The spring sleeve110is disposed between the valve rod141and an upper end of the pole housing160; thus enabling the spring sleeve110to be supported at the valve rod141as well as on the inside at the pole housing160. The spring sleeve110comprises two hollow cylindrical or annular end sections111,113and a plurality (for example: three, four or five) of connecting webs112that connect the end sections111,113. The end section111is disposed on the housing160, and the other end section113is disposed at the upper end of the valve rod141.

The spring sleeve110, which can be manufactured, for example, in a simple and cost effective manner from a metallic material such as, in particular, spring steel, has the form of a Chinese lantern due to the connecting webs112and the recesses in the lateral surface thereof and due to a curvature directed (radially) outwards. A curvature of the spring sleeve110is present in the open as well as in the closed switching state of the valve (seeFIGS. 1 and 2).

The connecting webs112of the spring sleeve110act like leaf spring legs so that the spring sleeve110contracts in the axial direction (i.e. with respect to a longitudinal extension of the sleeve110or to an adjustment travel of the valve rod141) when force is applied and the connecting webs112expand (“bulge”) outwardly in a transverse direction upon said application of force. Each of the connecting webs112can be understood as an arrangement of two adjacent limbs of a toggle lever, wherein corresponding “pivot points” can be located at the transition of the connecting webs112to the end sections111,113and in a central region of each connecting web112. In the first switching position of the valve rod141that is shown inFIG. 1, the spring sleeve is situated in an axially compressed and outwardly expanded state. As a result, the spring sleeve110is pressed by the valve rod141against the pole housing160. The spring sleeve100is dimensioned such that, in the event of the spring sleeve110longitudinally contracting by the length of the adjustment travel of the valve rod141, the lateral extension of said spring sleeve110is substantially larger than the longitudinal contraction due to the toggle lever effect. When the valve rod141is deflected into the second switching position as illustrated inFIG. 2, the spring sleeve110can independently assume the depicted, substantially axially elongated shape having a slight curvature, whereby the spring sleeve110has with respect to the first switching position a larger longitudinal dimension and a smaller lateral dimension. The curvature outwards, which is also present in this state, serves to predefine the lateral extension behavior of the spring sleeve in order to particularly prevent the connecting webs112from bending towards the inside.

The locking device of the solenoid valve100, with the help of which the spring sleeve110used to support the valve rod141can be locked, comprises, as is shown inFIG. 1, an axially displaceable holding element121, a spring element122disposed between the holding element121and the upper section of the pole housing160, an armature element125that encloses the valve rod141and is axially displaceable with respect to said valve rod141and a further return spring127. The holding element121that is supported by means of the spring element122at the pole housing160can be moved starting from the initial position shown inFIG. 1into a locking position when closing the valve100with the aid of the spring element122. The holding element121rests against the spring sleeve110or encloses the same (seeFIG. 2) in said locking position. This will be discussed in greater detail below. The holding element121has a disc-shaped or annular base section which surrounds an (axial) circular opening. On the outside, the holding element121has an edge section that extends perpendicularly to the base section, across which edge section the holding element121can slide on the inside along the pole housing160.

The armature element125, which is formed from a ferromagnetic material, is supported by means of an axially displaceable sleeve123at the holding element121. The sleeve123and the spring element122are thereby disposed at opposite sides of the holding element121. The holding element121and the sleeve123can both be constructed from a plastic material. The further return spring127is disposed between the movable armature element125and the solenoid armature135arranged on the valve rod141and can exert a force on said two armature elements125,135which acts to pull them apart. As is indicated inFIGS. 1 to 3, the further return spring127and the spring element122can be embodied in the form of coil springs. In addition, an enclosing guide sleeve129is provided in the pole housing160for mechanically guiding the movable armature element125and the movable sleeve123. In so doing, said armature element125and said sleeve123can move axially within the guide sleeve129. Said guide sleeve129is likewise constructed from a ferromagnetic material.

The spring sleeve110and the individual springs122,127,137are adjusted with regard to the spring effects thereof such that the valve100in the currentless state also assumes the open switching position shown inFIG. 1or is held in said position without being influenced by a coolant pressure acting on the port181. To this end, the spring constant K137of the return spring137is greater than the sum of the spring constants K110, K122, K127of the spring sleeve110and of the springs122,127, i.e.
K137>(K110+K122+K127).

In addition, the further return spring127has a larger spring constant than the spring element122, i.e.
K127>K122,

whereby the holding element121can be moved away from the locking position in the currentless state of the coil139.

The functionality of the spring sleeve110and the locking thereof is described below in detail using a closing operation of the valve100. The valve100is thereby initially located in the (first) open or currentless switching state shown inFIG. 1. In order to close the valve100, a magnetic field is generated by supplying current to the field coil139, whereby the yoke131, the solenoid armature135and the movable armature element125are magnetized. Due to the attractive force that occurs in the process between the solenoid armature135and the yoke131, the valve rod141is moved downwards into the (second) closed switching position shown inFIG. 2while compressing the return spring137. In addition, an attractive force is present between the movable armature element125and the solenoid armature135, whereby the armature element125is moved towards the solenoid armature135while compressing the further return spring127. In so doing, the guide sleeve129can bring about the guidance of magnetic field lines between the pole housing160and the movable armature element125.

In the closed state of the valve100, the sealing cone145is pressed via the valve rod141with a sufficiently large sealing force against the valve seat155, which force is greater than a predetermined minimum force. The minimum force, which can, for example, be 20N, is determined by the counteracting force which can substantially be induced by the return spring137and the hydraulic coolant pressure. In this state, the spring element147disposed between the sealing cone145and the valve rod141is (somewhat) tensioned or contracted. (Axial) component tolerances can be compensated via the spring element147; thus enabling the sealing cone145to be held with the intended sealing or closing force against the valve seat, and thereby enabling the valve100to be securely closed.

The movement or deflection of the valve rod141into the closed or second switching position further has the consequence that the spring sleeve100, starting from the compressed state, can axially expand (seeFIG. 2). The associated lateral contraction of the spring sleeve110results in said spring sleeve110tapering to a smaller lateral dimension or to a minimum diameter. Because the movable armature element125is additionally pulled in the direction of the solenoid armature135, the spring element122that is supported at the housing section of the pole housing160(and was previously contracted) can expand and thereby press the holding element121together with the sleeve123away from the relevant pole housing section. In this way, the holding element121is moved starting from the initial position shown inFIG. 1into the locking position in which the holding element121rests against the spring sleeve110. In the locking position, the holding element121is, as shown inFIG. 2, is centrally (i.e. with respect to the axial direction) arranged on the spring sleeve110, which can be achieved by means of an appropriate embodiment of the valve100, in particular of the length of the sleeve123located between the holding element121and the armature element125. The holding element121or the internally situated opening thereof is dimensioned such that only the reduction of the lateral dimension of the spring sleeve110enables the movement into the locking position.

In the locking position, the spring legs or connecting webs112of the spring sleeve110can be supported at an edge surrounding the opening of the holding element121or at an internal lateral surface that is present here. In this way, the holding element121can provide an adequate holding force which counteracts a lateral extension and thus an axial compression of the spring sleeve110; thus enabling the spring sleeve110to obtain a relatively high degree of axial rigidity. The valve rod141can therefore be supported on the spring sleeve110, whereby the valve100can be held closed in a reliable manner.

The closing force of the valve100is now—in contrast to a conventional solenoid valve—no longer solely dependent on the magnetic attraction between the solenoid armature135and the yoke131but additionally on the locking of the valve rod141achieved with the aid of the holding element121and the spring sleeve110. As a result, it is possible to largely reduce the supply of current to the field coil139after the closed valve state and activation of the locking of the valve rod141have been achieved. For example, it is possible to reduce the electrical current by approximately 90% to approximately a tenth of an initial value (i.e. of a current value during the closing process). The reduced or minimum current supply to the coil results substantially solely for the purpose of retaining the holding element121in the locking position. The electrical current (“holding current”) is therefore determined substantially by the attractive force between the movable armature element125and the solenoid armature135, the spring constants of the return spring127and the spring element122and by the frictional force between the spring sleeve110and the holding element121.

The locking of the valve rod141as per the previously described mechanism additionally offers the possibility of dimensioning the field coil139of the valve100substantially smaller with respect to a conventional solenoid valve. In so doing, the dynamics of the closing process as well as the closing force of the valve can remain unchanged or, as the case may be, even be increased.

In order to open the valve100, the minimum supply of current to the field coil139is undershot or switched off. This results in the attractive force between the movable armature element125and the solenoid armature135sinking or falling off to such an extent that the return spring127located between said two components can displace the movable armature element125and thereby the sleeve123and the holding element121axially upwards against the force of the spring element122, as is shown inFIG. 3. This is possible because the spring constant K127as specified above is greater than the spring constant K122. The holding element121is therefore moved away from the locking position thereof, whereby the connecting webs112of the spring sleeve110can no longer be supported on the inner lateral surface of the holding element121and as a result the spring sleeve110loses the high axial rigidity thereof. In this way, the solenoid armature135and thus the valve rod141can be moved upwards into the first switching position while compressing the spring sleeve110due to the influence of the of the return spring137(and possibly due to the influence of a coolant pressure), whereby the valve100can again assume the open state shown inFIG. 1. This opening mechanism implements a reliable behavior in the event of a fault or, respectively, a fail-safe function of the valve100because said mechanism is automatically triggered in the event of faults (for example: voltage drop, loss of contact, etc.).

In the open valve state, the sealing cone145is (again) separated from the valve seat155. To this end, the adjustment travel of the spring element147disposed between the sealing cone145and the valve rod141is dimensioned such that the maximum axial tolerance of the valve100is not exceeded, and thereby the opening stroke of the sealing cone145and a cross-sectional surface area of the valve100specified for the volume flow are not undershot.

The spring sleeve110which acts as a toggle lever mechanism and is supported at the pole housing160can basically convert an externally acting holding force, which can act radially or laterally on the connecting webs121, into a supporting force that acts axially on the valve rod141. Due to the toggle lever effect, the ratio of holding force to supporting force is nonlinearly dependent on the respective (contracted) shape of the spring sleeve110and hence on the deflection of the valve rod141. Said nonlinear behavior is used in the case of the valve100to implement the locking of the spring sleeve110and thus the valve rod141with a relatively small holding force. As described above, the holding force is transmitted here only in the axially elongated state of the spring sleeve110by the holding element that has been moved into the locking position onto the spring sleeve110. In this state, the holding force transmitted by the holding element121onto the spring sleeve110is substantially smaller than the supporting force acting on the valve rod141. By means of the spring sleeve110, a relatively small holding force can therefore be converted into a relatively large supporting force which acts on the valve rod141and holds the valve100closed. Likewise a large application of force by the valve rod141onto the spring sleeve110(=counteracting force with respect to the supporting force) only results in a small application of force by the spring sleeve110onto the holding element121(=counteracting force with respect to the holding force). This makes it possible to again move the holding element121reliably and with relatively little effort away from the locking position with the aid of the return spring127.

With regard to the possible reduction or minimization of the current supplied to the field coil, the significant influencing variables will be additionally examined below. In the closed and locked state of the valve100, the magnetic attractive force acting between the armature element125and the solenoid armature135overcompensates for the resulting spring force of the springs122,127that are working against each other. A minimum attractive force for maintaining the closed state can thus be achieved with a smallest possible difference between the spring constants of the springs122,127.

It must further be taken into account that the valve100can be exposed to vibrations depending on the mounting position thereof. This case is, for example, relevant if the valve100is disposed at a combustion engine of a motor vehicle. For that reason, the maintenance of the closed valve state requires that an acceleration force which occurs here and pulls the armature element125away from the solenoid armature135be likewise compensated by the magnetic attractive force. Because the attractive force exponentially increases when the distance between the armature element125and the solenoid armature135decreases, the minimization of the current consumption in the closed valve state can be promoted by a distance between the two armature elements125,135which is as small as possible. In so far as a direct contact between the armature element125and the solenoid armature135is not possible during the closing process for reasons of noise emissions, a relatively thin, annular plastic disc (having a thickness of, for example, maximally 0.1 mm) can if need be disposed between the armature elements125,135for noise damping purposes. The acceleration force acting on the movable armature element125can further be minimized as a result of the armature element125being dimensioned as small as possible and hence being light. By optimizing these influencing variables (i.e. dimensioning of the springs122,127, minimum distance between the armature elements125,135, dimensioning of the movable armature element125), the possibility exists for the electrical current supplied to the valve100or, respectively, the holding current in the closed valve state to be reduced to less than 10% of the current that is supplied in the case of a conventional embodiment of the solenoid valve.

With regard to the valve100, differently constructed support devices can also be used instead of the spring sleeve110, which devices can be disposed in a comparable manner between the valve rod141and the upper section of the pole housing160and can be locked to the holding element121via the locking device as well. Possible embodiments are described in detail with the aid of the subsequent figures. It must be noted that with regard to details that have already been described and refer to similar or corresponding components and features (for example the functionality of the electromagnetic actuation device and the locking device of the valve100), possible advantages etc., reference will be made to the previous embodiments.

FIGS. 4 to 6show a support device210in a perspective and side view which is directly designed in the form of a toggle lever mechanism. The support device210has two plate-shaped end sections211,214, between which two support structures in the form of adjacent side sections212,213are disposed. The side sections212,213form the limbs of a toggle lever. With regard to a use in the valve100, the end section211can, for example, be disposed on the pole housing160; and the other end section214can be disposed on the valve rod141as indicated inFIGS. 5 and 6.

As is further shown inFIGS. 5 and 6, the end sections211,214are connected via integral hinges216to the side sections212,213. The adjacent side sections212,213are also connected to one another via integral hinges216. As a result, the side sections212,213can be rotated and thereby deflected relative to each other and also with respect to the end sections211,214. The arrangement consisting of the end sections211,214, the side sections212,213and the integral hinges216can, for example, be designed in the form of a plastic injection molded part.

The support device210further comprises a spring element219disposed between the end sections211,214, wherein said spring element can be in the form of a coil spring as indicated inFIGS. 5 and 6. Due to the restoring spring element219, the support device210can independently assume the elongated shape shown inFIG. 5. Here the side sections212,213on the sides of the support device210are aligned so as to extend (slightly) obliquely outwards which is caused by a parallelogram-like cross-sectional shape of the side sections212,213. By means of this embodiment, the lateral extension behavior of the support device210can be predefined, i.e. that the support device210comparable to the spring sleeve110only carries out a lateral extension when an axial force is applied. Such an application of force resulting in a longitudinal contraction, which can be induced by displacing the valve rod141resting against the end section214into the first switching position pursuant toFIG. 1, is shown inFIG. 6. In comparison to the state depicted inFIG. 5, the side sections212,213are in this case angled more sharply outwards so that the support device210has a larger lateral dimension.

The support device210can therefore, similarly to the spring sleeve110, be locked in the manner described above with the aid of the holding element121. In the state shown inFIG. 6(valve rod141in the first switching position, open valve100), the holding element121is located in the initial position thereof. In order to close the valve100, the valve rod141is deflected into the second switching position pursuant toFIG. 2by energizing the field coil139. The support device210can thus pass into the elongated state shown inFIG. 5, in which the support device210has a minimal lateral dimension. As a result, the holding element121can be moved into the locking position, in which the holding element121can rest in a central position against the support device210or, respectively, against the side sections212,213. The holding element121or more precisely the internal opening thereof is dimensioned such that only the reduction of the lateral dimension of the support device210enables the movement into the locking position. Depending on the shape of the support device210, the holding element can, for example, have in this case a rectangular or square opening instead of the circular opening described above.

In the locking position, the holding element121can provide a corresponding holding force that counteracts a lateral extension and an axial compression of the support device210. As a result, the support device has a relatively high degree of axial rigidity; thus enabling the valve100to be held closed in a reliable manner. In so doing, it is once again possible to reduce the current supply to the field coil139to a minimum value. If said minimum current supply to the coil is cut off (or is undershot) and as a result the holding element121is moved away from the locking position, the support device210loses the high degree of rigidity. For that reason, the support device210can (against the force of the spring element219) be axially compressed, whereby the valve rod141can return into the first switching position.

Due to the toggle lever effect, the support device210supported at the pole housing160likewise exhibits a relationship between a holding force acting externally on the support device210or, respectively, on the side sections212,213thereof and a supporting force acting on the valve rod141which is nonlinearly dependent on the deflection of the valve rod141. The holding force provided by the holding element121is substantially smaller than the supporting force in the axially elongated state ofFIG. 5. Hence, the release of the lock, by means of which the holding element121is moved away from the locking position thereof, can be carried out with a relatively small expenditure of force.

A support device having a nonlinear transmission behavior can also be implemented in another manner than by means of the toggle lever mechanism. Possible embodiments are described with the aid of the subsequent figures.

FIGS. 7 and 8show a side view of a further support device310which has substantially triangular support elements311that are arranged mirror-symmetrically to one another. The support elements311are connected via a hinge315to one another at “corner points” which face each other and can therefore be moved or pivoted relative to one another. Within the scope of the application in the valve100, the valve rod141is supported on the inside between wedge-shaped partial sections313of the support elements311. At a side opposite thereto, the support elements311comprising wedge-shaped partial sections312are supported at the pole housing160, i.e. at or within a receiving structure161provided here. The receiving structure161comprises a trapezoidal recess having wall sections which extend obliquely outwards. Similarly, the partial sections312of the supporting elements311are provided with beveled ends. A simplified sliding of the partial sections312during the rotational movement of the support elements311is enabled by this embodiment of the receiving structure161and the partial sections312.

The support element310further comprises a spring element319which is disposed between the partial sections312of the support elements311and can be embodied in the form of a (bent) leaf spring as is indicated inFIG. 7. By means of the restoring spring element319, the support elements311can be independently rotated into the position shown inFIG. 7so that the support device310has an axially elongated, expanded shape.

By means of an axial application of force that is induced by displacing the valve rod141disposed between the partial sections313of the support elements311into the first switching position pursuant toFIG. 1, the support elements311can be rotated into the position shown inFIG. 8. In so doing, the partial sections313of the support elements311are pressed apart—and the partial sections312, while compressing the spring element319, are pressed on top of each other or against each other. In the state depicted inFIG. 8, the support device310has a larger lateral dimension with respect to the state depicted inFIG. 7.

As a result, the support device310can likewise be locked with the aid of the holding element121in the manner described above. In the state shown inFIG. 8(valve rod141in the first switching position, open valve100), the holding element121is located in the initial position thereof. In order to close the valve100, the valve rod141is deflected into the second switching position pursuant toFIG. 2by energizing the field coil139. The support elements311can thereby be rotated via the spring element319into the position depicted inFIG. 7, in which position the ends of the partial sections313lie relatively close to one another and consequently the support device310has a small(er) lateral dimension. As a result, the holding element121can be moved into the locking position, in which said holding element121can rest externally against the support device310or against the ends of the partial sections313. The holding element121or more precisely the internal opening thereof is dimensioned such that only the rotational movement of the supporting elements311into the position shown inFIG. 7enables the movement into the locking position. Depending on the shape of the support device310, the opening of the holding element121can also have, for example, a rectangular or square contour in this case.

In the locking position, the holding element121can provide a corresponding holding force which counteracts an opposite rotation of the support elements311. As a result, the support device310has a relatively high degree of stability or rigidity, whereby the valve100can be held closed in a reliable manner. The current supply to the field coil139can therefore also be reduced to a minimum value in this case. If the minimum supply of current to the field coil is cut off (or is undershot) and consequently the holding element121is moved away from the locking position, the support device310loses the high degree of rigidity. The valve rod141can therefore again press the partial sections313apart and rotate the support elements311into the position shown inFIG. 8, thus enabling the valve rod141to return into the first switching position while the support device310is being axially “reduced in size”.

The support device310supported at the pole housing160or at the receiving structure161likewise exhibits a relationship between a holding force acting externally on the support device310or, respectively, on the partial sections313and a supporting force acting on the valve rod141which is nonlinearly dependent on the deflection of the valve rod141. In the axially expanded state ofFIG. 7, the holding force provided by the holding element121is substantially smaller than the supporting force. The release of the lock can therefore be carried out with a relatively small expenditure of force.

FIGS. 9 and 10show a side view of a further support device410which comprises two support elements411that can be displaced relative to one another. The support elements411have substantially wedge-shaped partial sections412, on the obliquely extending front faces of which the support elements411can slide along each other. One of the support elements411is rotatably arranged and supported on the valve rod141, and the other of the two support elements411is rotatably arranged and supported on the pole housing160or, respectively, on a fastening section165provided here. To this end, the support elements411have web-shaped partial sections413extending from the partial sections412. Hinges416are provided on the ends of the web-shaped partial sections413for the rotatable connection to the valve rod141and to the fastening section165. In so doing, one or also two of such partial sections413located at opposite sides of the valve rod141and the fastening section165can be provided per support element411. In order to improve the support and the guidance of the rotatable support elements411, the partial sections412as well as the end of the valve rod141and the end of the fastening section165are configured having curved or part-circular contact surfaces that are matched to one another.

The support device410furthermore comprises two spring elements, which are disposed in the region of the two hinges416and can be present in the form of arcuate leaf springs. With the aid of the restoring spring elements419, which can rest with one end against the web-shaped partial sections413, the support elements411can independently be rotated into the position shown inFIG. 9in which the support device410has an axially elongated or expanded shape.

The support elements411can be rotated into the position shown inFIG. 10by means of an axial application of force that is induced by displacing the valve rod141into the first switching position pursuant toFIG. 1. In the process, the support elements411are rotated in directions opposite each other or, respectively, are rotated away from each other while pressing the spring elements419apart, wherein the support elements411can slide along each other on the oblique surfaces of the partial sections412. In the state depicted inFIG. 10, the support device410has a larger lateral dimension in relation to the state depicted inFIG. 9.

Due to this functionality, the support device410can be locked in the manner described above with the aid of the holding element121. In the state shown inFIG. 10(valve rod141in the first switching position, open valve100), the holding element121is located in the initial position thereof. In order to close the valve100, the valve rod141is deflected into the second switching position pursuant toFIG. 2by energizing the field coil139. With the aid of the spring elements419, the support elements411can be rotated here towards each other and therefore into the position shown inFIG. 9so that the support device has a small(er) lateral dimension. The holding element121can thereby be moved into the locking position, in which the holding element121can rest externally against the support device410or, respectively, against the ends of the partial sections412. The holding element121or more precisely the internal opening thereof is dimensioned such that only the rotational movement of the support elements411into the position shown inFIG. 9enables the movement into the locking position. Depending on the shape of the support device410, the opening of the holding element121can have, for example, a rectangular or square contour.

In the locking position, the holding element121can provide a corresponding holding force which counteracts a rotational movement of the support elements411directed against the same. The support device410consequently has a relative high degree of stability; thus enabling the valve100to be held closed in a reliable manner. It is therefore possible to reduce the current supply to the field coil139to a minimum value. If the minimum supply of current is cut off (or is undershot) and as a result the holding element is moved away from the locking position, the support device410loses the high degree of rigidity. Hence, the valve rod141can again press or rotate the support sections411apart, whereby the valve rod141can again be returned into the first switching position while the support device410is being axially “reduced in size”.

The support device410supported at the pole housing160or, respectively, at the fastening section165likewise exhibits a relationship between a holding force acting externally on the support element410or, respectively, on the partial sections412and a supporting force acting on the valve rod141which is nonlinearly dependent on the deflection of the valve rod141. In the axially elongated state ofFIG. 9, the holding force provided by the holding element121is substantially smaller than the supporting force. The release of the lock can therefore occur with a relatively small expenditure of force.

The embodiments described with the aid of the figures represent preferred or exemplary embodiments of the invention. Instead of the described embodiments, further embodiments are conceivable which can comprise further modifications to the features described. In particular, it is conceivable to implement differently structured support devices in which a nonlinear behavior can likewise exist between a holding force and a supporting force. Said nonlinear behavior can therefore similarly be used in a locked state to convert a holding force into a substantially larger supporting force that acts on the valve rod.

A different construction is also conceivable for a locking device or more precisely a holding element of such a locking device. For example, a holding element can be provided which has an abutment portion only at one position or in a certain region. In the locking position of such a holding element, the abutment portion can rest against a support device in order to counteract a lateral extension of the support device and thereby lock said support device.

In addition, the approaches described above are not only limited to currentless, open cut-off valves but can also be used with differently structured solenoid valve types. A possible exemplary embodiment is a changeover valve. Such a solenoid valve can comprise a first and a second closing element which are disposed at different positions on a valve rod. In a first switching position, the first closing element can rest against an associated first valve seat and close the same, whereas a second valve seat is not closed. By the valve rod (again induced by energizing a field coil) deflecting into the second shifting position, the previously closed first valve seat can be opened and the second valve seat can be closed by the second closing element, a changeover function thereby being implemented. In this case, a holding element can be similarly moved into a locking position against a support device provided for supporting the valve rod, whereby the support device locks and thus the supply of current to the field coil can be reduced.