Abstract:
A valve assembly ( 1 ) comprising a valve housing ( 2 ), a stem ( 4 ) that is disposed perpendicular to the direction of flow within the valve housing ( 2 ), and a blocking member ( 3 ) which can be movably connected to the stem ( 4 ). The stem ( 4 ) is provided with a device ( 5 ) for limiting torque.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a valve assembly comprising a valve housing with a valve seat, a spindle which is arranged in the valve housing, the spindle being arranged perpendicularly with respect to the flow direction, and a shutoff element which can be connected movably to the spindle and has a sealing element. 
     In pipeline construction, different valve designs are used in order to shut off pipelines which are pressurized and carry medium. Different factors play an important role in the selection of the valve design: the sealing action between the valve seat and the sealing element, the coefficient of resistance of the valve, the dimensions and the production costs of the valve. 
     DE 196 46 275 A1 has disclosed a valve, in which the valve spindle is arranged so as to extend perpendicularly with respect to the flow direction. The shutoff element and the sealing element are arranged at two different angles to the flow direction. The actual sealing element, an O-ring, is integrated into the valve housing on its outer circumferential face. The axes of the inflow and outflow lines are arranged offset with respect to one another, which leads to a higher coefficient of resistance. More than half the annular circumferential face lies free and is exposed to the flowing medium when the valve is open. The sealing action of the O-ring is not distributed uniformly over the entire circumference. The O-ring is loaded and deformed in an upper region above all in the direction of the O-ring axis. In a lower region the O-ring is loaded and deformed above all in the radial direction. 
     Proceeding from this prior art, it is an object of the invention to specify a valve assembly which can be produced simply and compactly from as few individual parts as possible and ensures as satisfactory a sealing action as possible. 
     SUMMARY OF THE INVENTION 
     The foregoing object is achieved by a valve assembly comprising a valve housing with a valve seat, a spindle which is arranged in the valve housing, the spindle being arranged perpendicularly with respect to the flow direction, and a shutoff element which can be connected movably to the spindle and has a sealing element, characterized in that the spindle has an apparatus for limiting the torque. 
     It is advantageous that the valve assembly is corrosion-resistant and functions reliably over a very long time. This is achieved by the fact that the apparatus for limiting the torque is formed from a first cage region which is operatively connected to the spindle and from a second disk region which is operatively connected to an actuating apparatus. The cage region and the disk region are formed completely from plastic. Metal springs or other individual parts which make the assembly of the valve assembly complicated or corrode are not used. 
     It is also advantageous that the coefficient of resistance of the valve is kept as low as possible and thus the pressure loss in the pipeline is kept as small as possible. This is achieved by the fact that the first lower housing region has a T-shaped cross section, the axes of the inflow and outflow lines being arranged in one line. 
     It is also advantageous that the sealing action is distributed as uniformly as possible on the entire sealing element. This is achieved by the fact that a sealing element which is formed obliquely with respect to the flow direction and so as to correspond to the inclined slope of the valve seat is arranged on the shutoff element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One exemplary embodiment of the invention will be described using the figures, in which: 
         FIG. 1  shows a section through a valve assembly according to the invention in the completely open state, 
         FIG. 2  shows a section through the valve assembly of  FIG. 1  in the completely closed state, 
         FIG. 3  shows a section through an apparatus for limiting the torque in the valve from  FIG. 1 , 
         FIG. 4  shows a perspective view of the apparatus for limiting the torque in the valve from  FIG. 1 , 
         FIG. 5  shows a section through the apparatus for limiting the torque in the valve from  FIG. 1  in the completely open state, 
         FIG. 6  shows a section through the apparatus for limiting the torque in the valve from  FIG. 1  in the completely closed state, 
         FIG. 7  shows a section through a further valve with an apparatus for limiting the torque in the completely closed state, and 
         FIG. 8  shows a section through the valve of  FIG. 7  with an apparatus for limiting the torque in the completely closed state. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  and  FIG. 2  show sections through a valve assembly  1  with a valve housing  2 , a shutoff element  3 , a spindle  4  for actuating a shutoff element  3 , and an apparatus  5  for limiting the torque which occurs during the actuation of the spindle  4 . The valve housing  2  comprises a first lower housing region  6  and a second upper housing region  7 . The valve assembly  1  is produced completely from plastic parts, that is to say from corrosion-resistant parts. A lifting valve  1  is shown here as an exemplary embodiment of the valve assembly  1 ; according to the invention, all other valve designs, a spindle  4  being used, can also be equipped with an apparatus  5  for torque limitation. 
     The first housing region  6  is of substantially T-shaped configuration and has two connecting regions  8 ,  9  for connection to the inflow and outflow lines (not shown here) which carry medium. The axes of the inflow and outflow lines are arranged in a line. This achieves a situation where, when the valve is open, the medium can flow through the valve  1  as far as possible without resistance. The shutoff element  3  is substantially a cylindrical plunger  10  with an internal thread  11  which interacts with a matching thread on the spindle  4 . A rotation of the spindle  4  in the clockwise direction causes the plunger  10  to move perpendicularly downward in the valve housing  2  and the valve to be closed. A rotation in the counterclockwise direction likewise causes the plunger  10  to be raised and the lifting valve  1  to be opened. 
     A commercially available O-ring is inserted as actual sealing element  13  in a groove  12  which is formed obliquely, that is to say at an angle with respect to the spindle axis S, on the outer circumference of the plunger  10 . The groove  12  is configured so as to match the O-ring  13  and in the process encloses the O-ring  13  over a large part of the circumference, for example from more than 270° to over 300°, of the O-ring  13 . This achieves a situation where, during opening of the valve, the O-ring  13  cannot be flushed out of the groove  12  even at high flow speeds. A valve seat  31  is formed in the lower housing region  6  between the connecting regions  8 ,  9  perpendicularly below the spindle  4 , the valve seat  31  being arranged at the same angle as the O-ring  13  with respect to the spindle axis S. 
     The second upper housing region  7  is fastened to a shoulder or a flange  14  of the first lower housing region  6  by a screw connection or a welded connection. An intermediate plate  15  can be seen between the end side of the flange  14  and the neck of the upper housing region  7 . The intermediate plate  15  serves firstly during opening of the shutoff element  3  as stroke travel limiting means of the plunger  10  and secondly as guide for the spindle  4 . The spindle  4  extends through a central hole of the intermediate plate  15 . 
     For sealing purposes, a further groove  16  for an O-ring seal can be seen in the central hole. The seal between the spindle  4  and the intermediate plate  15  is arranged at the smallest possible diameter in order to keep the forces which act on said seal as low as possible. The lower housing region  6 , through which the medium flows, is sealed with respect to the upper housing region  7  by way of an additional O-ring seal in a receptacle  30  between the lower housing region  6  and the intermediate plate  15 . 
     The upper end of the spindle  4  is configured as a cage region  17 . A disk region  18  which is formed at the lower end of an actuating rod  19  engages into the cage region  17 . The disk region  18  has a toothing system  20  on the outer circumference and the cage region  17  has a further mating toothing system  21  on the inner circumference, which toothing systems  20 ,  21  are in engagement with one another during normal operation of the lifting valve  1 . The torque securing of the lifting valve  1  is achieved by the division in two of the valve actuation: the actuating rod  19  with the disk region  18  at the lower end and the spindle  4  with the cage region  17  at the upper end. 
       FIG. 1  shows the lifting valve  1  in the completely open state and  FIG. 2  shows the lifting valve  1  in the completely closed state. When the lifting valve  1  is opened completely, the cage region  17  is displaced downward with respect to the actuating rod  19  with the disk region  18  until the spindle  4  rests with the cage region on the intermediate plate  15 . Likewise, when the lifting valve  1  is closed completely, as shown in  FIG. 2 , the cage region  17  is displaced upward with respect to the disk region  18 . 
     It can be seen in  FIGS. 3 and 4  how the toothing system  20 ,  21  is formed. The cage region  17  is formed as a ring of a plurality of, for example eight, radially resilient wall regions  22 . At least one toothing system  21  which engages into a matching mating toothing system  20  on the circumference of the disk region  18  can be seen on each wall region  22 . If the permissible torque of the rotational movement of the spindle  4  is exceeded, the wall regions  22  yield radially outward with the teeth  21  and no longer forward the force which is exerted on the actuating rod  19  and on the disk region to the cage region  17 , to the spindle  4  and to the shutoff element  3 . 
     In the case of an individual wall region  22  of the cage region  17  with a tooth  21 ,  FIG. 4  shows, on an enlarged scale and in perspective, as viewed in the direction of the spindle axis S, a detail of the disk region  18  with a mating toothing system  20 . The length L of the tooth  21  is greater than the height H of the disk region  18 . The mating toothing system  20  can therefore be displaced axially in the direction of the spindle axis S and remains in engagement with the tooth  21  in the process. 
     The tooth  21  has two tooth flanks  23 ,  24  with different flank angles α, β. A flank angle α which is flatter than the angle of the mating toothing system  20  has the result that the contact face between the tooth  21  and the mating toothing system  20  is smaller, and that the teeth  20 ,  21  can slide away over one another under the action of force which is exerted by the rotational movement of the spindle  4 . If the flank angle β of the tooth  21  is the same size as the flank angle of the mating toothing system  20 , the contact face between the teeth  20 ,  21  is larger and the force which is transmitted is likewise larger. This means that a greater force can be transmitted in the case of a rotational movement in one direction than in the opposite direction. 
     It can also be seen in  FIG. 4  how the flank angles α, β change continuously with the length L of the tooth  21  in the wall region  22 . At the end of the wall region  22 , the tooth flanks  23 ,  24  have in each case the flank angles α, β to the tooth flanks  23 ,  24  which lie opposite in each case. The continuous transition from a greater flank angle α to a smaller flank angle β on the side of the first tooth flank  23  and the simultaneous transition of the flank angles from β to α on the side of the second tooth flank  24  achieve a situation where there is a slipping coupling, or a limitation of the torque, at both ends of the rotational movement, that is to say in the first and in the second end positions of the lifting valve  1 . The flank angle β is substantially smaller than the flank angle α, it also being possible for the flank angle β to be 0°. 
       FIGS. 5 and 6  show sections of the toothing systems  20 ,  21 .  FIG. 5  shows the position of the disk region  18  and the cage region  17  in the completely open state of the lifting valve  1 , and  FIG. 6  shows the corresponding position in the completely closed state. The section from  FIG. 5  is indicated in  FIG. 1  with the line A-A, and the section from  FIG. 6  is indicated in  FIG. 2  with the line B-B. In the completely open state of the lifting valve  1  ( FIG. 1 ), the cage region  17  of the spindle  4  rests with a base plate  32  on the intermediate plate  15  and the disk region  18  is situated at the upper end of the cage region  17 . In the completely closed state of the lifting valve  1  ( FIG. 2 ), the base plate  32  of the cage region  17  of the spindle  4  rests on a shoulder  33  in the upper housing region  7  and the disk region  18  is situated at the upper end of the cage region  17 . 
       FIGS. 7 and 8  show a further exemplary embodiment of a valve assembly  1  with an apparatus  5  for limiting the torque. Here, the apparatus  5  for limiting the torque, as in  FIGS. 1 and 2 , comprises a disk region  18  which is formed at the lower end of the actuating rod  19 . The disk region  18  has a toothing system  20  which is formed at the upper end of an intermediate piece  35  with a mating toothing system  21  on a radially resilient cage region  17 . At the lower end, the intermediate piece  35  has a threaded region  36 , in which a spindle  37  is arranged. 
     The spindle  37  is formed in one piece with the shutoff element  38 . Sealing apparatuses  39 ,  40  are formed on the shutoff element  38 . The sealing apparatuses  39 ,  40  can be inserted into the mold of a plastic injection molding device and can be encapsulated or coated with the plastic of the shutoff element  38 . The sealing apparatuses  39 ,  40  are produced, for example, from a thermoplastic elastomer and are coated with the polyethylene composition of the shutoff element  38 . An intermediate plate  15 , as in  FIGS. 1 and 2 , can be omitted. The overall height of the valve assembly of  FIGS. 7 and 8  is substantially lower than the overall height of the valve assembly of  FIGS. 1 and 2 . As a result, the use of a valve  1  with torque limitation  5  is possible even in the case of reduced space conditions. The valve assembly from  FIGS. 7 and 8  which is constructed only from five individual parts is of substantially simpler construction than the valve assembly from  FIGS. 1 and 2 . 
     The assembly which is proposed here affords a torque limiting means  5  which provides the same security against overloading both in the closed and in the open state. All the parts are produced from plastic and no balls are required which are difficult to handle and which jam after a relatively long time. A metal spring which loses the spring force and/or corrodes after a relatively long time is not required either. A very compact design with as few individual parts as possible can be achieved because the spring action is integrated into the plastic component of the cage region  17 . The spindle  4  with the torque limiting means  5  has only an insubstantially greater diameter than the actual shutoff element  3 . 
     The lifting valve  1  is used, above all, in water lines which are laid underground. The lifting valve  1  does not have to be actuated very often here. Even after a relatively long unactuated time, the lifting valve  1  still absorbs the forces which are necessary for a correct actuation. The torque limiting means  5  shown here and comprising a disk region  18  and a cage region  17  can also be used in other valve designs and in other objects, in which torque limitation is required.