Abstract:
Proposed is a pinch valve ( 1 ) which has a hose-like valve element ( 3 ), an actuating element ( 18 ) arranged on the outer circumference of the valve element ( 3 ), and at least one radially movable plunger ( 33   a   , 33   b ) arranged between the actuating element ( 18 ) and the valve element ( 3 ). On the inner side ( 39 ) of the actuating element ( 18 ) there is situated at least one actuating surface, which extends in the circumferential direction and at the same time axially and which bears against a plunger ( 33   a   , 33   b ). By way of guide means ( 28   a   , 28   b ), it is ensured that, in the event of rotation of the actuating element ( 18 ), the actuating surface slides on the at least one plunger ( 33   a   , 33   b ) and pushes the latter radially inward, because the spacing of the actuating surface to the valve element ( 3 ) varies over the longitudinal profile thereof.

Description:
This application claims priority based on an International Application filed under the Patent Cooperation Treaty, PCT/EP2012/001343, filed Mar. 28, 2012, which claims priority to DE102011015385.3, filed Mar. 29, 2011. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a pinch valve with a hose-like valve element having a longitudinal axis, and an actuating element that is disposed on the outer circumference of the valve element and that is rotatable, executing an actuating movement, relative to the valve element in the circumferential direction thereof, and, in addition, having at least one plunger, which while executing an operating movement can be optionally moved toward the inside in the direction of the valve element or, to the opposite, toward the outside, transversely relative to the longitudinal axis of the valve element for the purpose of pinching the valve element more or less intensely and which is disposed between the valve element and the actuating element, and wherein the actuating element at the inner side thereof that is directed toward the valve element includes at least one actuating surface serving for a pressing application of force to the at least one plunger and sliding off the at least one plunger when executing the actuating movement, wherein the actuating surface has a longitudinal profile extending at least in part in the circumferential direction of the valve element with a changing spacing in relation to the valve element. 
     A pinch valve of this kind is disclosed in U.S. Pat. No. 3,920,215 and contains a longitudinal, hose-like valve element that is surrounded by a housing-type enveloping body and extends between two fluid connections. Disposed coaxially on the enveloping body is an axially immovably fixed actuating element that is, however, rotatable relative to the valve element in the circumferential direction thereof. The enveloping body is radially slotted and interspersed by two radially displaceable plungers that rest, on the one hand, on the outer circumference of the valve element and, on the other hand, on an actuating surface that is configured on the inner side of the actuating element. The actuating surface has a longitudinal profile that is oriented relative to the circumferential direction of the valve element, wherein the radial spacing thereof relative to the valve element is changing over the length thereof. In other words, the course that the actuating surface takes corresponds to the profile of a longitudinal section of a spiral that is disposed at a right angle relative to the valve element. When the actuating element is rotated relative to the enveloping body, and thereby also relative to the valve element, the spiral-like actuating surface slides off the rear of the plunger allocated thereto and presses the same, to a more or lesser degree, radially to the inside. 
     A disadvantage of the pinch valve that is known from the prior art is the fact that there is a relatively large gear ratio between the rotational movement of the actuating element that functions as the actuating movement and the operating movement of each actuating element that is derived therefrom. Correspondingly, there results a high actuating force. Moreover, intermediate positions of the plunger can only be guaranteed by means of latching steps, which are instrumental in causing impairments, as they result in a certain heaviness of the actuating movement, do not allow for a stepless adjustment of the desired cross-section of flow and are ultimately subject to a relatively high wear and tear. 
     DE 69232487 T2 discloses a valve closure that operates in the manner of a pinch valve in that it provides that a hose can be locked by means of a radially movable compression element, for example a ball, in that a cam applies force to the compression element; and the cam is configured on the internal surface of a tube-shaped housing part, and a housing part that receives the hose can be screwed onto the same. 
     U.S. Pat. No. 2,987,292 discloses a pinch valve with a hose that can be pinched by radially movable balls, which can be actuated by means of a rotatable disc. The disc features curved actuating surfaces on the internal circumference thereof for applying force to the balls. 
     SUMMARY OF THE INVENTION 
     Therefore, it is the object of the present invention to provide a pinch valve that allows for an easy actuating movement of the actuating element, which can be finely dosed. 
     To achieve this object, it is envisioned, in conjunction with the characteristics as mentioned in the introduction, that the longitudinal profile of the at least one actuation surface includes at least partially an axial component in the axial direction of the longitudinal axis of the valve element that is superimposed over the circumferential direction of the valve element, wherein the actuating movement of the actuating element is a combination of a rotational movement and a related, at least phase-wise superimposed axial displacement movement, such combination of movement being defined by guide means. 
     Especially expedient in this context is a related construction that provides that the longitudinal profile of the actuating surface is continually composed of components that are superimposed relative to each other in the circumferential direction and the longitudinal direction of the valve element. This results, in particular, in a helical longitudinal profile of the actuating surface. 
     Due to the longitudinal profile according to the invention of the at least one actuating surface and due to the associated circumstance whereby the actuating movement is, due to the available guide means, a corresponding combination of a rotational movement and a, related thereto, at least in part superimposed axial displacement movement, it is possible to implement, if necessary, a very easy actuating movement that can be finely dosed. Compared to the prior art, with a comparable operating stroke of the at least one plunger, it is possible to coordinate herein a longer section of the actuating surface with the plunger to generate the operating movement of said plunger. Correspondingly, the radial spacing variation between the actuating surface and the valve element can be spread further apart and distributed over a greater rotational movement and/or a greater angle of rotation of the actuating element, thereby resulting in a smaller gear ratio, such that the adjustment forces required for actuating the actuating element can be maintained at a low level. This way, there also exists the possibility, in particular, of restricting the actuating surface over the longitudinal profile thereof to such a moderate degree that, even without steps to achieve a form closure, a self-inhibition is present based on the frictional closure alone, with the consequence that the actuating element stably maintains any adjustment position independently of the prevailing fluid pressure and without additional auxiliary forces and/or a catch. 
     By the measure according to the invention, it is also possible to achieve a tapering of the actuating surface in such a way that the performance characteristic of the throughflow of the flow medium that is controlled by the pinch valve is linearized. Correspondingly, it is possible to achieve especially precise and reproducible dosing of the throughflow. 
     Advantageous improvements of the invention are captioned in the dependent claims. 
     Expediently, the actuating surface that cooperates with a respective plunger is formed by the delimiting surface of an at least in part non-linear groove that is disposed on the inner side of the actuating element and into which the allocated plunger protrudes by an actuating section thereof intended to apply force to the actuating section in order to generate the operating movement. In particular, the actuating section, which protrudes into the groove, is an end section of the plunger that is oriented opposite to the valve element. The delimiting surface is preferably a base area of the groove that has adjacent thereto, on both sides, flanks of the groove that is able to act, in relation to the longitudinal axis of the valve element, in a radial direction from axially outside on the related plunger. 
     Expediently, the actuation section of the plunger that engages in the groove has a tapered configuration, such that, even when the actuating surface is spread wide in the longitudinal direction of the valve element, there is no jamming risk between the plunger and the flanks of the groove. To implement the changing spacing with regard to the longitudinal direction of the groove, it is expedient for the depth of the groove to be changing in the longitudinal direction of the groove, specifically over at least a part of the length of the groove, preferably over the entire length of the groove. 
     The guide means can be configured independently of the at least one plunger. However, the structural form that provides for the at least one plunger to be one of the guide means and that contributes itself directly by being a guide means to the fact that the actuating movement is a superimposed rotational and displacement movement of the actuating element that follows the longitudinal profile of the actuating surface is particularly preferred. In this context, it is advantageous for the at least one plunger and the delimiting surface of the allocated groove together to constitute the guide means, wherein the plunger plunges into the groove and has force applied thereto by the flanks of the groove, such that the actuating element is caused to perform the special actuating movement thereof, due to the interaction of the grooves and plunger that engage with each other, when the corresponding actuation and/or displacement forces are applied to the actuation element from the outside. The actuation movement can be generated, in particular, by applying a torque to the actuating element. 
     As indicated previously, it is advantageous when the longitudinal profile of at least one actuating surface is at least partially helical. 
     As a matter of principle, the pinch valve can be provided with only a single movable plunger that acts on the valve element from one side, such that the pinch valve can be pinched between the movable plunger and a stationary counter-surface. Presumably, however, it is more advantageous for the valve element to include a plurality of individual plungers that are distributed in the circumferential direction around the valve element. This way, it is possible to reduce the stroke of the individual plungers that is necessary to optionally completely release or close off the cross-section of flow. 
     A dual arrangement of plungers is considered particularly expedient, where it is envisioned to dispose two plungers on two diametrically opposed sides of the outer circumference of the valve element. To close the valve element, when executing the actuation movement, both plungers are simultaneously pressed, coming from two opposite sides, in the radial direction toward the inside and against the outer surface of the wall of the valve element. 
     The pinch valve can be configured such that a plurality of plungers cooperates with the same actuating surface, respectively, wherein only the places of the instantaneous cooperation in the longitudinal direction of the actuating surface are spaced relative to each other. In such a case, it is typically possible, however, to implement the actuating surface as having only a very minimal incline, when the plungers are to be disposed in the axial direction of the valve element at the same height lying opposite each other. Or, in the alternative, special molding steps for the movable plunger are needed. Simpler means, which translates into cheaper means, that must therefore be preferred involve, as a matter of fact, a structural form having at least two of the available plurality of plungers with different actuating surfaces, meaning they cooperate with one own actuating surface thereof, respectively. Each plunger that is present expediently cooperates with one own actuating surface thereof. If the pinch valve is provided with two plungers, the actuating element thus carries two actuating surfaces. 
     All the actuating surfaces of one and the same actuating element are expediently distributed in the circumferential direction of the valve element, offset relative to each other on the actuation element, wherein this circumferential offset is, in particular, 180°. Among themselves, the plurality of actuating surfaces have an identical longitudinal profile. Moreover, they are preferably disposed at the same height in the longitudinal direction of the valve element. 
     An especially advantageous configuration of the pinch valve provides for a plurality of non-linear grooves that are disposed on the inner side of the actuating element in the manner of a multiple-start thread, in which engages one of the plurality, respectively, of the plungers, which are distributed along the outer circumference of the valve element and disposed at the same axial height thereof in relation to the longitudinal profile of the valve element, and wherein each groove functions both as an actuating surface and as a guide means. 
     Expediently, the actuating element is configured as sleeve-like and disposed in such a manner that it coaxially encloses the valve element. It can be configured as longer or shorter than the valve element. 
     Expediently, the pinch valve has an enveloping body that encloses the valve element in a concentric fashion, and the sleeve-like actuating element is preferably disposed, rotatably and axially displaceably, on the outer circumference thereof. The enveloping body can also directly constitute a housing of the pinch valve. Furthermore, the enveloping body comprises a number of radial passages that expediently matches the number of available plungers, and which are interspersed in a radially displaceable manner, respectively, by at least one plunger for executing the operating movement thereof. 
     The enveloping body can be configured in one piece or in multiple pieces. Preferably, said body is made up of two shell-like support elements that are placed, coming from diametrically opposed sides, to the outside on the valve element, and further of an external tube that coaxially encloses the shell-like support elements from the outside. Each passage therein intersperses at least one support element as well as the external tube. 
     Expediently, the external tube is connected, by a form closure by means of rolling or by means of another shaping method, to the end elements on the frontal side that define a fluid connection, which respectively communicates with a valve channel that intersperses the valve element. 
     The enveloping body is preferably configured as smooth, such that reliable and easy guiding action is achieved for the actuating element that must be moved in a combination-type rotational and axially displacing manner. 
     It is possible to dispose an indicator scale on the outside surface of the enveloping body that extends in the longitudinal direction of the valve element, which is axially covered up at varying widths by the actuating element as a function of the adjustment position thereof. This way, it is possible to take an easy reading of the currently adjusted value of the released flow cross-section. 
     The actuating element can be configured, in particular, for the manual or machine-type introduction of an actuating force that generates the actuation movement. Similarly, it is possible to envision a configuration that allows for optionally introducing manual or machine-type actuating forces. For the machine-type introduction of the actuating force, the pinch valve is expediently equipped with an electric drive motor that is coupled to the actuating element in such a manner that it is able to power the same. The coupling can be achieved, for example, by means of a gear train. The actuating element therein can include, directly on the outer circumference thereof, a gear-type toothing that meshes with a drive gear that can be powered by a drive motor. With a machine-type and/or motor-type drive means powering the actuating element, it is possible to detect the degree of release of the cross-section of flow of the valve element, particularly by means of a displacement measuring system. For example, it is possible to detect the current operating state of the pinch valve by means of the rotary movement of a drive motor, whereby no position-detecting means involving the actuating element is necessary. 
     The pinch valve according to the invention also opens up the possibility of gradually adjusting the actuating element, bringing the same in the respectively desired position in a stepless manner. Although the actuating movement of the actuating element is composed of a rotational movement and a superimposed axial displacement movement that is related thereto, the actuating force can preferably be introduced into the actuating element exclusively as a torque. The axial movement component of the actuating movement results from the at least one guide means that accommodates the at least one actuating surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in further detail below based of the enclosed drawings. Shown are as follows: 
         FIG. 1  depicts a perspective exterior view of a preferred embodied example of the pinch valve according to the invention in the maximum open position thereof; 
         FIG. 2  depicts a side view of the pinch valve from  FIG. 1 ; 
         FIG. 3  depicts a front view of the pinch valve, with a view according to arrow III from  FIG. 2 ; 
         FIG. 4  depicts a view of a longitudinal section of the pinch valve in the maximum open position, along a sectional line IV-IV from  FIG. 2 ; 
         FIG. 5  depicts a cross-section of the pinch valve in the maximum open position, along a sectional line V-V from  FIGS. 2 and 4 ; 
         FIG. 6  depicts an eccentric longitudinal section through the pinch valve in the maximum open position, along sectional line VI-VI from  FIG. 4 ; 
         FIG. 7  depicts an exterior perspective view of the pinch valve in the closed position, completely sealing the valve element; 
         FIG. 8  depicts the pinch valve in the closed position from  FIG. 7  in a side view; 
         FIG. 9  depicts the pinch valve in the closed position, in a longitudinal section along the sectional line IX-IX from  FIG. 8 ; 
         FIG. 10  depicts the pinch valve in the closed position along a sectional line X-X from  FIGS. 8 and 9 ; 
         FIG. 11  depicts the pinch valve in a state in which the actuating element has been removed; 
         FIG. 12  depicts a further embodied example of the pinch valve having means for the machine-type, particularly motor-powered, actuation; and 
         FIG. 13  depicts a cross-section of the arrangement from  FIG. 12  along a sectional line XIII-XIII. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The pinch valve as a whole is designated by the reference numeral  1  and configured such that it is able to variably prescribe the cross-section of flow that is available for a flow medium when said medium flows through a valve channel  2 . 
     In this regard, the pinch valve  1  of the embodiment is able to provide a closed position in which any flow is completely prevented from passing through ( FIGS. 7 to 10 ), an open position in which the flow cross-section is maximally wide ( FIGS. 1 to 6 ) and any—particularly gradual-intermediate position between the open position and the closed position, where the cross-section of flow is between zero and the maximum available cross-section. 
     A flow medium that must be controlled is typically a gas or a liquid. However, the pinch valve  1  is also able to influence the flow rate of other fluid media, wherein particularly powder- or granulate-type materials are considered therein. 
     The pinch valve  1  has a hose-like valve element  3  with a longitudinal axis  10  and extending, preferably, over a linear extension. Said valve element  3  has two end sections  4   a ,  4   b  that are axially disposed opposite of each other and interspersed by a valve element channel  5  delimiting the same, which opens at the frontal side on the two end sections  4   a ,  4   b.    
     The wall area of the valve element  3  is radially flexible with regard to the longitudinal axis; particularly, it is elastically deformable. This deformability relates particularly to a control area  6  that is disposed at a distance relative to one of the two end sections  4   a ,  4   b , and which is disposed in an axial central position between the two end sections  4   a ,  4   b . Preferably, however, the totality of the valve element  3  has rubber-elastic properties throughout. 
     In the neutral state, which is when no radial force is applied from the outside, the valve element has a configuration wherein the channel of the valve element  5  is continuously open, thus releasing the maximum possible cross-section for accommodating the flow. 
     Expediently, the hose-like valve element  3  is coaxially enclosed by a rigid enveloping body  7 . By way of an example, this enveloping body  7  is a component of a housing  8  of the pinch valve  1  that encloses the valve element  3 . In the non-deformed, neutral state of the valve element  3 , the enveloping body  7  rests against the radially outwardly oriented outer circumference  12  of the valve element  3 , and it prevents inflation of the valve element  3 , when atmospheric excess pressure is present in the channel of the valve element  5 . 
     Following each of the preferably flange-like configured end sections  4   a ,  4   b  is, expediently, one of two close-off elements  13   a ,  13   b  that are expediently also part of the housing  8  that define each a fluid connection  14   a ,  14   b . The fluid connection  14   a ,  14   b  is characterized by a fluid channel that intersperses the related connection element  13   a ,  13   b  with allocated connection means  15  that allow for connecting a continuing fluid line, particularly in a detachable manner. By way of an example, the connection means  15  are constituted of a thread; however, a plug and socket connection, for example, is possible as well. 
     The valve element  3  rests against the respectively following close-off element  13   a ,  13   b  by the circularly shaped contoured end sections  4   a ,  4   b , axially sealing the same. This way, there results a fluid-proof transition between the channel of the valve element  5  and each fluid connection  14   a ,  14   b , wherein the channel of the valve element  5  defines the valve channel  2  of the pinch valve  1  together with the two fluid connections  14   a ,  14   b.    
     Preferably, the enveloping body  7  contains an external tube  16  that extends between the two connection elements  13   a ,  13   b . Expediently, said tube has a circular-cylindrical outer circumferential area  17 . The outer circumferential area  17  is, in particular, configured as smooth, such that it can advantageously function as a slide and/or guide surface for an actuation element  18  that will be described in further detail below. 
     The external tube  16  is connected to the respectively allocated close-off element  13   a ,  3   b  by way of the two axial end sections  22   a ,  22   b  that are diametrically opposed relative to each other. Expediently, the fastening connection is without screws and without any additional fastening elements and achieved solely by a plastic reshaping of the mentioned end sections  22   a ,  22   b . Each close-off element  13   a ,  13   b  plunges somewhat coaxially into the external tube  16  and expediently includes, in the area of the outer circumference thereof, a concentric, radially opened ring groove  23 , and the allocated end section  22 ,  22   b  of the external tube  16  is radially pressed into said ring groove by a force-type or form-type closure, for example by means of rolling. 
     Correspondingly, together, the external tube  16  and the connection elements  13   a ,  13   b  constitute one rigid unit. 
     The enveloping body  7  is expediently configured in multiple parts. By way of an example, it has, in addition to the external tube  16 , a support body  24  that is coaxially disposed between the external tube  16  and the valve element  3 , and which is configured in a sleeve-like manner and includes on the inner circumference thereof a support surface  25  that encloses the valve element  3 , and the contour of which corresponds to the outer contour valve element  3 , when the valve element is in the maximally open position. The support surface  25  prevents any radial inflation of the rubber-elastic valve element  3 . 
     The support body  24  expediently comprises two individual shell-like support elements  24   a ,  24   b , respectively, that are placed, coming from two diametrically opposed sides, radially from the outside against the valve element  3  and that complement each other to form a sleeve-like support body  24 . The support elements  24   a ,  24   b  are held together by the external tube  16  that is placed thereupon. The assembly is simplified because the support body  24  is made up of multiple parts. 
     Deviating from the embodiment, however, the enveloping body  7  can also be configured in one piece. 
     The previously mentioned actuating element  18  is guided in a slidable manner on the outer circumference  17  of the enveloping body  7 . Expediently, the actuating element  18  is configured in a sleeve-like manner and disposed coaxially relative to the valve element  3 . The axial length thereof is less than that of the external tube  16 . 
     The actuating element  18  is able to carry out a rotational movement  26  in relation to the valve element  3 , as indicated by the double arrow, in the circumferential direction thereof. The circumferential direction of the valve element  3  is the direction around the longitudinal axis  10 . The longitudinal axis  10  constitutes the imagined axis of rotation for the rotational movement  26  of the actuating element  18 , wherein the radial position of the actuating element  18  in relation to the valve element  3  is achieved by the interaction with the outer circumferential surface  17  of the enveloping body  7  that is enclosed by the actuating element  18 . 
     The actuating element  18  is, furthermore, able to execute an axial displacement movement, as indicated by a double arrow  27 , which means a translational movement in the direction of the axis of the longitudinal axis  10 . Unless indicated to the contrary in the individual case, the term “axial” refers to the direction of the axis of the longitudinal axis  10 . 
     However, the actuating element  18  is not feely movable to execute the rotational movement  26  and the axial displacement movement  27 . Rather, first and second guide means  28   a ,  28   b  are provided that cooperate with each other and that ensure that the actuating element  18  is only able to execute an actuation movement  32 , as indicated by a double arrow, which is a fixedly prescribed combination of the rotational movement  26  and the displacement movement  27 , wherein the rotational movement  26  and the displacement movement  27  are superimposed at least in part during the execution of the actuating movement  32 . 
     To control the flow-through of a flow medium through the channel of the valve element  5 , the pinch valve  1  expediently includes two plungers  33   a ,  33   b , which are referred to as first and second plungers  33   a ,  33   b  for an easier understanding, and which are disposed, respectively, in the radial intermediate space between the valve element  3  and the actuating element  18 . Although, as a matter of principle, it is possible to provide a different number of plungers  33   a ,  33   b ,—the pinch valve  1  could include only one such plunger or more than two plungers—, using a dual arrangement of plungers  33   a ,  33   b  has proved especially expedient. 
     Each plunger  33   a ,  33   b  intersperses, in terms of the configuration thereof, a correspondingly adjusted radial passage  34   a ,  34   b  of the enveloping body  7  in the radial direction. Each plunger  33   a ,  33   b  therein is displaceable in relation to the enveloping body  7  at a right angle, and particularly in a radial direction, in relation to the longitudinal axis  10 . The displacement movement of the plungers  33   a ,  33   b , that is thus possible, will be referred to below as the operating movement  35 . In particular, this is a linear movement. 
     In the context of the operating movement  35 , each of the plungers  33   a ,  33   b  can optionally be moved radially to the inside in the direction toward the valve element  35  or in the related opposite direction radially toward the outside. 
     The operating movements  35  can be generated by the actuating element  18 , when said actuating element executes an actuation movement  32 . In other words, the actuating element  18  functions as a drive element for the plungers  33   a ,  33   b . The actuating element  18  cooperates, in particular, with the two plungers  33   a ,  33   b  in such a manner that these two plungers  33   a ,  33   b  execute their operating movements  35  synchronously, respectively, either simultaneously radially toward the inside or simultaneously radially toward the outside. 
     Each plunger  33   a ,  33   b  can take an end position that is maximally radially displaced to the outside, as illustrated in  FIGS. 4  und  5 . The plungers  33   a ,  33   b  rest therein without preload or only with a minimal preload on the control area  6  on the outer circumference  12  of the valve element  3 . Therefore, the valve element is in the maximum open position thereof. 
     The two plungers  33   a ,  33   b  can, moreover, assume a maximum inner end position, which is a maximally displaced position toward the inside, where they clamp the valve element  3  between each other creating an elastic deformation in such a manner that the closed position of the valve element  3  is achieved, in which the passage through the channel of the valve element  5  is interrupted. 
     The closed position of the valve element  3  that can be discerned based on  FIGS. 9  und  10  is demonstrated by way of an example in that the plungers  33   a ,  33   b  cause the, in particular, wall sections  36   a ,  36   b , which are disposed as diametrically opposed relative to each other, of the wall that encloses the channel of the valve element  3  to be pinched until they make contact with each other. The wall sections  36   a ,  36   b  come to rest against each other in a sealing fashion. 
     The two plungers  33   a ,  33   b  are expediently placed in the area of circumferential areas of the valve element  3  that are diametrically opposed in relation to each other. Therefore, in relation to the longitudinal axis  10 , they are disposed diametrically opposite each other. The operating movements  35  thereof are expediently oriented parallel in relation to each other. Both operating movements  35  therein expediently extend in a radial direction relative to the longitudinal axis  10 . 
     While, by way of an example, the plungers  33   a ,  33   b  are configured in one piece, as a matter of principle, they can also be structured in multiple parts. 
     Each plunger  33   a ,  33   b , independently of the radial position thereof that it takes with regard to the enveloping body  7 , protrudes somewhat radially toward the outside extending beyond the outer circumferential area  17 . In other words, each plunger  33   a ,  33   b  has an outer end section  37  that is disposed opposite in relation to the valve element  3  and outside of the enveloping body  7 . Preferably, it is this end section  37  that constitutes an actuating section  38  that cooperates with the actuating element  18  to cause the operating movement  35 . 
     The preferably sleeve-like actuating element  18  includes at the radial inner side  39  thereof, which is directed toward the valve element—that are constituted, in an exemplary manner of the inner circumference of the actuating element  18 —a number of non-linear grooves  42   a ,  42   b  that correspond to the number of available plungers  33   a ,  33   b . Corresponding to the dual number of plungers  33   a ,  33   b , which are available in the embodiment, the actuating element  18  has at the inner side  39  thereof or at the internal circumference thereof, respectively two grooves  42   a ,  42   b , which will be referred to below as first groove  42   a  and second groove  42   b.    
     The two grooves  42   a ,  42   b  are open on the inner side that is directed toward the valve element  3 . Preferably, they have at least partially, and particularly over the entire length thereof, a helical or spiral-like longitudinal profile. 
     Expediently, the two grooves  42   a ,  42   b  are configured in the manner of a multiple-start thread, wherein they are disposed at the same axial height between each other in relation to the axial direction of the actuating element  18 , and they are only offset relative to each other in relation to the circumferential direction of the valve element  3 . Said circumferential offset amounts, in particular, to 180° . In relation to each other, the available grooves  42   a ,  42   b  expediently have identical longitudinal profiles. 
     Each plunger  33   a ,  33   b  extends by the actuating section  38  thereof in one of the two grooves  42   a ,  42   b , from radially inside. Correspondingly, the plungers  33   a ,  33   b  engage in different grooves  42   a ,  42   b.    
     Expediently, the two plungers  33   a ,  33   b  are disposed at the same height in the axial direction of the longitudinal axis  10 . Preferably, they also have a linear longitudinal profile transversely in relation to the longitudinal axis  10 . Correspondingly, they engage by the end sections  37  thereof, that constitute the actuating sections  38 , at the same axial height as the actuating element  18  in different grooves  42   a ,  42   b.    
     Each groove  42   a ,  42   b  is delimited by a delimiting surface  45  that defines the contour of the cross-section of the related groove  42   a , 42   b . By way of an example, the delimiting surface  45  comprises per groove  42   a ,  42   b  a base surface  43  that is disposed opposite the groove opening and two lateral groove flanks  46  that are directed toward each other in the axial direction of the longitudinal axis  10 . 
     In the embodiment, the cross-section of the groves  42   a ,  42   b  is advantageously configured in a trapezoidal shape, such that the base surface  43  as well as the two groove flanks  46  both have a straight cross-sectional contour. Expediently, the groove flanks  46  are, moreover, configured in such a manner that, starting from the base surface  43 , they diverge toward the groove opening. Correspondingly, each groove  42   a ,  42   b  is tapered in the depth direction thereof. 
     Expediently, it is the base surface  43  of a respective groove  42   a ,  42   b  that constitutes the actuating surface  44 , which collaborates with the allocated actuating section  38  in terms of a drive function and pressing there-against. Each plunger  33   a ,  33   b  supports itself by the actuating section  38  thereof, radially from the inside, on the base surface  43 , and thus on the actuating surface  44  constituted thereof. It is clear, therefore that the operating position of each plunger  33   a ,  33   b , meaning the position each plunger  33   a ,  33   b  can assume in the context of the operating movement  35 , depends on which radial spacing exists between the instantaneously cooperating surface section of the actuating surface  44  and the longitudinal axis  10 . 
     This previously mentioned circumstance is taken into consideration in the context of the present pinch valve in that each groove  42   a ,  42   b  includes over the longitudinal profile thereof a changing and, particularly, continually changing groove depth. As a consequence, the actuating surface  44  that is constituted of the base surface  43  also has a longitudinal profile with a changing radial spacing with regard to the longitudinal axis  10 , and thereby also with regard to the valve element  3 . 
     Due to the helical longitudinal profile of the grooves  42   a ,  42   b , the actuating surface  44  also has a helical longitudinal profile, meaning a longitudinal profile that extends at least somewhat in the circumferential direction of the valve element  3  and that includes, in addition, an axial component that is superimposed relative to this circumferential direction and oriented in the axial direction of the longitudinal axis  10  of the valve element  3 . 
     The guide means  28   a ,  28   b , that were addressed previously, ensure that the actuating element  18  executes the previously mentioned actuating movement  26  when a torque is applied thereto, wherein at the actuating section  38  of each plunger  33   a ,  33   b , one of the actuating surfaces  45 , which extend in a spiral-like manner around the valve element  3 , slides off. Due to the guide means  28   a ,  28   b  that cooperate with each other, the actuating element  18  advances in a screw-like manner in the direction of the axis of the longitudinal axis  10  in relation to the valve element  3 . Simultaneously, the plungers  33   a ,  33   b  are gradually, and particularly continually, displaced toward the inside, while, simultaneously, the valve element  3  is pinched, because, at the actuating surfaces  38  thereof, one actuating surface  44  slides off respectively, and the radial spacing of which, that is taken up with regard to the longitudinal axis  10 , changes over the length of the longitudinal profile. 
     Advantageously, the guide means  28   a ,  28   b  are constituted, on the one hand, of the actuating section  38  and, on the other hand, by the groove flanks  46  of a respective groove  42   a ,  42   b . Correspondingly, each groove  42   a ,  42   b  and each actuating section  38  fulfills a dual function with regard to generating the adjustment force that is instrumental in causing the operating movement  35 , on the one hand, and guiding of the actuating element  18  during the screwing process thereof, on the other hand. The engagement of the plungers  33   a ,  33   b  in the grooves  42   a ,  42   b  is comparable to a threaded-type engagement, wherein the plungers  33   a ,  33   b  ensure, based on the position thereof, which is unchangeable in the axial direction of the longitudinal axis  10 , that the actuating movement  32  of the actuating element  18  results as a consequence of superimposing a rotational movement  26  and an axial displacement movement  27 . 
     To avoid any jamming risk between the actuating section  38  and the actuating element  18 , it is advantageous for the actuating section  38  to have a tapered outer contour in the area by which it engages in a groove  42   a ,  42   b , viewed from the perspective of the plunger  33   a ,  33   b  being in the axial direction of the longitudinal axis  10 . According to  FIGS. 5 and 10 , the end section can be rounded, in particular. 
     Looking at the structure of the actuating element  18 , which results from the at least one groove  42   a ,  42   b , the observer will notice that the grooves  42   a ,  42   b  define, by the protrusions that axially remain respectively there-between, the groove flanks  46  that serve for the guiding action; expediently, this is a tapered thread respectively. 
     Expediently, the axial incline of each spiral-like groove  42   a ,  42   b  is even. This allows, by the introduction of a torque in the actuating element  18 , an even advancing movement, as well as an even actuation of the plungers  33   a ,  33   b.    
     Moreover, it is advantageous for the degree of the changes in the spacing that occurs in the longitudinal direction of an actuating surface  44  with regard to the longitudinal axis  10  is such that, in each adjustment position of the actuating element  18 , a self-inhibition is created. Correspondingly, the plungers  33   a ,  33   b  maintain each adjusted operating position even in such instances when no external actuating force is any longer applied to the actuating element  18 . 
     The pinch valve in  FIGS. 1 to 11  is especially configured for manual actuation. The manual actuation occurs by the manual introduction of a torque, which is oriented in the circumferential direction of the longitudinal axis  10 , into the actuation element  18 . For example, it is possible to grasp the actuating element the grip of a hand and comfortably introduce the desired actuating torque in this manner. 
     The respectively realized flow-through adjustment can be very easily visualized with a display scale  47  that is disposed on the outer circumferential surface  17  of the enveloping body  7  extending in the longitudinal direction of the valve element  3 ; and said display scale acts in conjunction with the actuation element  18  that is axially adjustable in the context of the actuation movement  26 . Depending on the adjustment position of the actuation element  18 , said actuation element covers up the axial display scale  47  to a more or less comprehensive axial degree, which can be utilized as an indicator for the instantaneously applicable flow-through adjustment. 
     For example, an axially oriented frontal surface  52  can be utilized with regard to the instantaneous axial position thereof as a reference edge, and wherein the relative position thereof in relation to the indicator scale  47  reflects the respective operating state. 
     An advantage of the embodied pinch valve  1  is the fact that the cross-section of flow that is provided by the valve element  3  can be changed and adjusted in a stepless manner. The instantaneously adjusted value signifying the amount of opening can be easily derived from the axial position of the actuating element  18  in relation to the enveloping body  7 . Furthermore, there exists the advantageous possibility of selecting the longitudinal profile of the grooves  42   a ,  42   b  in such a manner that the angular rotation of the actuating element  18  during the execution of the actuating movement  26  and the related change of the cross-section of flow, that is defined by the valve element  3 , constitute a linear function. 
     To avoid fouling of the cooperation area between the plungers  33   a ,  33   b  and the longitudinal grooves  42   a ,  42   b , it is possible to provide the actuating element  18  in the area of the two frontal sides thereof with a seal in relation to the outer circumferential surface  17 . For example, the actuating element  18  can be provided with a sealing ring at the corresponding locations, and said sealing ring rests, with the ability of being displaced by sliding, against the outer circumferential surface  17 . 
     Expediently, the at least one groove  42   a ,  42   b  opens toward at least one axial frontal surface  52  of the actuating element  18 . If a plurality of grooves  42   a ,  42   b  are present, all grooves  42   a ,  42   b  expediently open toward the same axial frontal surface  52 . Expediently allocated to the axial frontal surface  52  is that end section of a respective groove  42   a ,  42   b  that has the greatest groove depth. Correspondingly, starting with the disassembled position as shown in  FIG. 1 , the actuating element  18  can be very easily placed on the enveloping body  7  and engaged in the actuating sections  38 , such that it is, advanced by said axial frontal surface, pushed onto the enveloping body  7  and, by means of the subsequent rotation, screwed on to the actuating sections  38 . The open end sections of the grooves  42   a ,  42   b  at the axial frontal surface  52  are hinted at in  53 . 
     The embodiment that is shown in  FIGS. 12 and 13  corresponds to the embodiment that is represented in  FIGS. 1 to 11 , except for the manner in which the actuating torque is introduced in the sleeve-like actuating element  18 . The differences consist particularly in that the torque, which generates the actuating movement  32 , is introduced in a machine-type fashion, particularly by way of a motor, into the actuating element  18 . 
     The pinch valve  1  as represented in  FIGS. 12 and 13  contains an electrical drive motor  54  the drive shaft of which is connected to a drive pinion, which includes an external toothing  56  that meshes with a ring gear  57  that is disposed around the outer circumference of the actuating element  18  that is radially opposite in relation to the valve element  3 . 
     A rotation of the drive pinion  55  that is generated by the drive motor  54  thus causes, due to the meshing of the teeth, a rotational movement  26  of the actuating element  18 , which has superimposed thereupon, due to the cooperation between the guide means  28   a ,  28   b , a displacement movement  27 , which results overall, as a consequence, in the actuation movement  32 . The axial movability of the actuating element  18  can be easily ensured in that the drive pinion  55  is disposed in a parallel alignment in relation to the longitudinal axis  10  of the valve element  3  of the longitudinal axis  58  thereof, and the external toothing  56  as well as the ring gear  57  are both configured having straight teeth, such that the actuating element  18  is able to slide off the drive pinion  55  when executing the displacement movement  27 . 
     The actuating force for generating the actuating movement  32  can also be generated in a machine-type fashion, for example by means of an electromagnetic drive unit or by a drive unit that is actuated by means of fluid force. 
     If a non-linear displacement behavior of the plungers  33   a ,  33   b  is desired, the actuating surface  44  can also be configured such that the distance thereof in relation to the valve element along the longitudinal direction thereof does not change continually, but that it changes, for example, with a changing incline. The axial incline of the spiral-like actuation surface  44  with regard to the longitudinal axis  10  can also be uneven. In addition, the configuration of the actuating surface  44  is not subject to any special restrictions, such that, in particular, there exists also the possibility to align one or a plurality of the longitudinal sections thereof in such a manner that they extend exclusively in the circumferential direction of the valve element  3  or exclusively in the longitudinal direction of the valve element  3 .