Abstract:
Known pressure regulating valves have a valve closing body, which cooperates with a valve seat, and a restoring spring, which acts on a valve closing body in the direction facing away from the valve seat. It is disadvantageous that the restoring spring is disposed in a pressure chamber, which has the valve seat and through which aggressive blowby gases flow out of the crankcase. The blowby gases for instance have a corrosive, etching effect on the material of the restoring spring, shortening the service life and lessening the spring force of the restoring spring. This has a highly adverse effect on the regulation of the pressure in the crankcase. In the pressure regulating valve of the invention, the service life of the restoring spring is increased. According to the invention, the restoring spring ( 31 ) is embodied as a tension spring and is located on the side of the valve closing body ( 15 ) facing away from the valve seat ( 12 ).

Description:
CROSS-REFERENCE 
   The invention described and claimed hereinbelow is also described in DE 10 2004 022275.4 filed May 6, 2004. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119 (a)–(d). 
   BACKGROUND OF THE INVENTION 
   The invention is based on a pressure regulating valve. 
   A pressure regulating valve is already known from German Patent DE 195 07 202 C2, having a valve closing body, which cooperates with a valve seat, and a restoring spring, which acts on a valve closing body in the direction facing away from the valve seat. It is disadvantageous that the restoring spring is disposed in a pressure chamber, which has the valve seat and through which aggressive blowby gases flow out of the crankcase. The blowby gases for instance have a corrosive, etching effect on the material of the restoring spring, shortening the service life and lessening the spring force of the restoring spring. This has a highly adverse effect on the regulation of the pressure in the crankcase. 
   SUMMARY OF THE INVENTION 
   The pressure regulating valve of the invention, having the definitive characteristics of the main claim, has the advantage over the prior art that in a simple way, an improvement is attained such that the service life of the restoring spring is increased and the spring force is kept constant, because the restoring spring is embodied as a tension spring and is located on the side of the valve closing body facing away from the valve seat. 
   In this way, the restoring spring is no longer exposed to the aggressive gases. 
   By the provisions recited in the dependent claims, advantageous refinements of and improvements to the pressure regulating valve defined by the main claim are possible. 
   It is especially advantageous if the restoring spring is embodied as a leaf spring, which is made from a flat steel or a wirelike round steel, because these are very economical, space-saving embodiments. 
   It is also advantageous if the valve closing body is embodied as a diaphragm, and the diaphragm has a valve closing portion, cooperating with the valve seat; a collar, provided on an edge of a diaphragm; and at least one crease of the diaphragm between the valve closing portion and the edge of the diaphragm. A pressure regulating valve embodied in this way is especially economical, since no further measures for guiding the valve closing body are necessary. 
   It is highly advantageous if the valve housing has a valve pot and a valve cap, and the valve closing body is fastened to the edge of the diaphragm between the valve pot and the valve cap. 
   It is also advantageous if the restoring spring rests loosely on the edge of the diaphragm and is supported in a recess of the valve cap. 
   In an advantageous feature, in the valve housing a valve interior is provided, which is divided by the valve closing body into a pressure chamber that has the valve seat and a ventilation chamber communicating with the atmosphere, and the restoring spring is disposed in the ventilation chamber. 
   It is furthermore advantageous if the restoring spring extends from the edge of the diaphragm to the diametrically opposite edge of the diaphragm, since in this way the restoring spring can be supported very simply. 
   It is also advantageous if the restoring spring is connected in material-, force- or form-locking fashion to the valve closing body in the region of a valve axis, since in this way the restoring spring can act on the valve closing body in the direction facing away from the valve seat. 

   
     BRIEF DECRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention are shown in simplified form in the drawing and described in further detail in the ensuing description. 
       FIG. 1  in section shows an elevation view of the pressure regulating valve of the invention. 
       FIG. 2  shows a first exemplary embodiment. 
       FIG. 3  shows a second exemplary embodiment. 
       FIG. 4  shows a third exemplary embodiment of the restoring spring of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a pressure regulating valve of the invention. 
   The pressure regulating valve of the invention is preferably employed in a crankcase venting system, for regulating a pressure in a crankcase to a constant value that is predetermined by the spring force of a restoring spring. However, it is also expressly possible for the pressure regulating valve to be used in other areas for pressure regulation. 
   During operation of an internal combustion engine, so-called blowby gas flows out of a combustion chamber into a crankcase, because of a slight leakage between the piston, piston rings, and cylinder running faces. For this blowby gas, the general term “gas” will also simply be used. Because of the slight leakage of gas from the combustion chamber of the engine, an impermissible increase in pressure occurs in the crankcase, making it necessary to achieve a pressure equilibrium by so-called crankcase venting. Since the gas has a high hydrocarbon concentration, the gas is carried by the crankcase venting not into the atmosphere but rather into an intake tube of the engine, so that from there it is delivered to combustion. The gas delivered to the intake tube has an oil fog with many large and small oil droplets, which occurs because of the gas flowing at high velocity into the crankcase and because of the moving parts in the crankcase. The oil droplets in the oil fog must be precipitated out of the gas stream, with the aid of a device for filtering out liquid, before being introduced into the intake tube, for the sake of avoiding a high oil loss and in order not to adversely affect combustion. 
   The pressure regulating valve has a valve housing  1  with a valve pot  2  and a valve cap  3  that closes the valve pot  2 . 
   The valve housing  1  has at least one inlet conduit  4 , which communicates for instance with a crankcase  5  of an internal combustion engine, and at least one outlet conduit  8 , which communicates for instance with an intake tube  9  of the engine. Between the crankcase  5  and the pressure regulating valve of the invention, a separator device  10 , for instance, is provided for precipitating out oil droplets. 
   The valve housing  1  has a valve interior  11 , defined by the valve pot  2  and the valve cap  3 , in which a valve closing body  15  that cooperates with a valve seat  12  is provided. A stub  17  protruding into the valve interior  11  is for instance located on a valve bottom  16  of the valve pot  2 . The outlet conduit  8  extends through the stub  17  and discharges into the valve interior  11  via a valve seat opening  20  that forms the valve seat  12  and is provided on a face end of the stub  17  oriented toward the valve closing body  15 . The valve closing body  15  is for instance located axially movably between the valve seat  12  and the valve cap  3  and divides the valve interior  11  into a pressure chamber  18  that has the valve seat  12  and a ventilation chamber  19  communicating with a reference pressure. The ventilation chamber  19 , for instance via a ventilating conduit  22  provided in the valve cap  3 , communicates with the atmosphere, but may also communicate with some other reference pressure. 
   The valve closing body  15  is embodied for instance as a diaphragm, which has a valve closing portion  23  that cooperates with the valve seat  12 . The diaphragm extends radially outward from the valve closing portion  23  and is fastened at an annular edge  24  of the diaphragm between the face end of the valve pot  2  facing away from the pot bottom  16  and the valve cap  3 . On the edge  24  of the diaphragm, an annular collar  25  is for instance provided, which protrudes into an annular groove  26  located on the face end of the valve pot  2  facing away from the pot bottom  16 . Between the edge  24  of the diaphragm and the valve closing portion  23 , at least one crease  29  of the diaphragm is provided, which makes the axial movability of the valve closing portion  23  in the direction of a valve axis  30  possible. The wall thickness of the valve closing portion  23  is greater for instance than that of the at least one crease  29  of the diaphragm and the collar  25 . The valve closing portion  23  is embodied cylindrically, for instance, and the wall thickness of the diaphragm  15  decreases either in stages and/or continuously at the transition from the valve closing portion  23  to the at least one crease  29  of the diaphragm. 
   The valve closing portion  23  is manufactured from an elastomer, a metal, or a plastic, for instance, and the remaining diaphragm with the at least one crease  29  of the diaphragm and the collar  25  is manufactured from an elastomer or plastic. 
   A restoring force of a restoring spring  31  acts on the valve closing body  15  in the direction facing away from the valve seat  12 . 
   According to the invention, the restoring spring  31  is embodied as a tension spring, which pulls the valve closing body  15  in the direction facing away from the valve seat  12 . 
   The restoring spring  31  is located on the side of the valve closing body  15  facing away from the valve seat  12 , for instance in the ventilation chamber  19 . In the ventilation chamber  19 , the restoring spring  31  is located between the edge  24  of the diaphragm  15  and the valve cap  3 ; beginning at the edge  24  of the diaphragm, it extends toward the diametrically opposite edge  24  of the diaphragm and rests loosely on each edge  24  of the diaphragm and is supported for instance on both of its ends in a respective recess  35  of the valve cap  3 . The recesses  35  in the valve cap  3  are each located in the region of the annular edge  24  of the diaphragm. In the region of the valve axis  30 , the restoring spring  31  is connected in form-locking, material-locking or force-locking fashion to the valve closing body  15 , for instance to the valve closing portion  23 . 
   The restoring spring  31  of the invention is for instance a leaf spring or a barlike spring, which is made from a flat steel or wire-shaped round steel and is manufactured from spring steel. 
   Upon the axial motion of the valve closing body  15  in the direction of the valve seat  12 , the restoring spring  31  is made to sag. The sagging of the barlike restoring spring  31  is made possible because the two ends of the restoring spring  31  are not fixedly fastened but instead rest loosely on the edge  24  of the diaphragm and are each capable of moving freely radially inward, relative to the valve axis  30 , in the recess  35  in the valve cap  3 . The recesses  35  allow no or only slight lateral motion of the restoring spring  31  transversely to the length of the restoring spring  31 . 
   When the pressure regulating valve is open, a pressure predetermined by the pressure in the intake tube  9  and the pressure in the crankcase  5  is established, which is for instance an underpressure and acts on the face of the diaphragm  15  oriented toward the pressure chamber  18 . 
   When the pressure regulating valve is closed, a pressure that is predetermined only by the pressure in the crankcase  5  is established in the pressure chamber  18 ; this is for instance a very sight overpressure and it acts on the face of the diaphragm  15  oriented toward the pressure chamber  18 , minus the surface area covered by the stub  17 . 
   At the diaphragm  15 , a force equilibrium is established, in which both a restoring force of the restoring spring  31  and a force that results from the difference in pressure between the pressure of the pressure chamber  18  and the pressure of the ventilation chamber  19  are involved. 
   When the pressure regulating valve is closed, an aspiration force is additionally involved, which results from the underpressure prevailing in the intake tube  9  and acting on the face of the valve closing body  15  that is covered by the valve seat opening  20 . 
   As a function of the force equilibrium, a predetermined opening spacing is established between the valve closing body  15  and the valve seat  12 . The smaller the opening spacing is, the less blowby gas volume can flow per unit of time into the intake tube  9 . 
   The spring force of the restoring spring  31  is designed such that the pressure regulating valve closes in a safety position whenever the underpressure in the intake tube  9  exceeds a predetermined value. This prevents the crankcase  5  from being sucked empty by an excessively great underpressure. The pressure that is established in the crankcase  5  is determined by the design of the spring force of the restoring spring  31 . Between the pressure chamber  18  and the outlet conduit  8 , a throttling bypass conduit  32  may be provided, which even when the pressure regulating valve is closed allows a minimum flow to flow out of the crankcase  5  into the intake tube  9 . 
     FIG. 2  shows a first exemplary embodiment of the restoring spring of the invention. 
   In the pressure regulating valve of  FIG. 2 , those parts that remain the same or function the same as in the pressure regulating valve of  FIG. 1  are identified by the same reference numerals. 
   In the first exemplary embodiment, the restoring spring  31  is a straight round wire, which extends from one edge  24  of the diaphragm to the diametrically opposite edge  24  of the diaphragm and is guided in the region of the valve axis  30  by a through opening  36  in the valve closing portion  23  and in this way is coupled mechanically to the valve closing body  15 . 
   In the region of the valve axis  30 , the valve closing portion  23 , on the side toward the ventilation chamber  19 , has for instance a circular indentation  42 , in which a crossbar  43  is located that extends from one edge of the indentation  42  to a diametrically opposite edge of the indentation  42 . The crossbar  43  protrudes for instance out of the indentation  42  in the direction of the valve cap  3 . The through opening  36  through which the restoring spring  31  protrudes is provided in the portion of the crossbar  43  that protrudes outward. 
   On its ends, the restoring spring  31  is loosely supported. 
     FIG. 3  shows a second exemplary embodiment of the restoring spring of the invention. 
   In the pressure regulating valve of  FIG. 3 , those parts that remain the same or function the same as in the pressure regulating valve of  FIG. 1  and  FIG. 2  are identified by the same reference numerals. 
   In the second exemplary embodiment, the restoring spring  31  is embodied as a barlike spring, which is shaped from a round wire in such a way that the two ends of the round wire are joined together or at least adjacent to one another, and in this way two legs  44  extending in the same direction, for instance, are formed, which extend from one edge  24  of the diaphragm to the diametrically opposite edge  24  of the diaphragm and are joined together via two crosswise legs  45 . On both of its ends, the restoring spring  31  protrudes past the respective edge  24  of the diaphragm and in each case engages the edge  24  of the diaphragm from behind because the ends are bent at an angle. 
   In the region of the valve axis  30 , on the side of the valve closing portion  23  toward the ventilation chamber  19 , there is a cylindrical shoulder  37 , which has an annular groove  38 . The restoring spring  31  is joined in form-locking fashion to the valve closing portion  23  in such a way that the two legs  44  extend in some portions through the annular groove  38 . For instance, the legs  44  enter the annular groove  38  approximately at a tangent, then in a portion corresponding to the annular groove  38  are bent into part of a ring, and then emerge from the annular groove  38  again approximately at a tangent. 
     FIG. 4  shows a third exemplary embodiment of the restoring spring of the invention. 
   In the pressure regulating valve of  FIG. 4 , those parts that remain the same or function the same as in the pressure regulating valve of  FIGS. 1 through 3  are identified by the same reference numerals. 
   In the third exemplary embodiment, the restoring spring  31  is embodied as a leaf spring, which is made from a flat steel. On both ends, the restoring spring  31  protrudes past the respective edge  24  of the diaphragm. The form locking of the restoring spring  31  to the valve closing portion  23  is achieved by providing that the valve closing portion  23 , on the side toward the ventilation chamber  19 , has a T-shaped groove  39 , through which the restoring spring  31  is guided.