Patent Publication Number: US-7721712-B2

Title: Pressure regulating valve

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a 35 USC 371 application of PCT/EP 2005/056150 filed on Nov. 22, 2005. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a pressure regulating valve, having an electromagnet and a movable armature, that is used in particular in a fuel injection system for internal combustion engines for regulating a pressure in a fuel reservoir. 
   Electromagnets with a movable armature are also used as actuators in manifold applications. 
   2. Prior Art 
   Manifold versions of pressure regulating valves are known. The pressure regulating valve serves to regulate the pressure in a fuel reservoir, with which it communicates via an inlet. The pressure regulating valve has a pistonlike valve member, which is guided axially displaceably in a bore and which can move counter to a force that acts on the valve member, preferably by means of the current in the electromagnet. The force acts in the closing direction, so that the valve member is pressed onto a closing element of the pressure regulating valve and is pressed against a valve seat. The valve member forms an armature bolt of an electromagnet, which can be supplied with current to control the force. 
   By means of the current supply, a magnetic field is created, which penetrates the armature of the electromagnet and causes a magnetic force to act on the armature bolt. With this force, the valve member presses the closing element against the valve seat. 
   If the force generated by the hydraulic pressure of the fuel exceeds the closing force that is exerted on the closing element via the valve member, then the closing element is lifted from the valve seat. In this case, fuel flows out of the fuel reservoir through the inlet via the opened pressure regulating valve into a relief chamber. 
   When a higher pressure is set in the fuel reservoir, the current in the electromagnet is increased, so that the closing force is increased, and thus the closing element does not lift from the valve seat until at a higher pressure in the fuel reservoir, and then fuel can flow out of the fuel reservoir into the relief chamber. 
   3. Disadvantages Of The Prior Art 
   Regulating the pressure in the fuel reservoir is done via the setting of the current in the coil of the electromagnet. The actual pressure thus depends on the parameters of the electromagnet. These include not only the electromagnetic parameters but also the geometrical dimensions. The air gap between the movable armature and the fixed valve housing, within which gap the coil of the electromagnet is located, is of particular importance. The air gap is defined by the component geometry. 
   To enable adjusting the pressure precisely or regulating a precise pressure interval, the components must be adapted to one another precisely. The requisite manufacturing tolerances are correspondingly low, which means major assembly effort and hence expense. 
   OBJECT OF THE INVENTION 
   The object of the invention is to refine the pressure regulating valve known from prior art, in such a way that adjusting the closing force of the valve can be done in a precise way, in the preassembled state. 
   The object is attained in a regulating valve according to the invention in which the spacing between the armature and the valve housing is definitive for the penetration of the armature by the magnetic field lines and accordingly for the magnetic force that can be transmitted by the armature and leads to the closing force of the pressure regulating valve. Detecting this spacing is done according to the invention by measuring a force generated by the magnetic circuit and from a travel measurement in a simultaneously occurring position of the valve member. These two physical variables can be detected very precisely and make a precise adjustment of the pressure regulating valve possible without mechanical tolerances and the material properties of the electromagnet having any influence. 
   In an advantageous embodiment, the current supply to the electromagnet is effected with a current that corresponds to the rated operating point of the pressure regulating valve, so that in this case conditions of the kind that occur later in operation of the pressure regulating valve as well are also present. 
   It is also advantageous that the current supply to the electromagnet is done in a regulated way, so that feedback effects on the measurements, especially upon positioning of the valve member, are avoided, and the current corresponding to the rated operating point of the pressure regulating valve prevails constantly. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One exemplary embodiment of the invention is described in further detail herein below, with reference to the drawings, in which: 
       FIG. 1  shows a schematic view of a pressure regulating valve in longitudinal section, to illustrate the mode of operation of the pressure regulating valve, and 
     In  FIG. 2 , also in longitudinal section, the pressure regulating valve is shown with only those parts that are of importance for the cooperation with schematically shown measurement systems for detecting a force and a travel. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In  FIG. 1 , a longitudinal section is shown through a schematic view of a pressure regulating valve  11  which can be disposed on a fuel reservoir, not shown in this drawing. 
   The pressure regulating valve  11  has a housing  12 , in which an electromagnet  13  with a coil winding  14  is located. The coil winding  14  is embedded in soft-magnetic material. 
   An armature bolt  16  of the electromagnet  13  is located in an axial recess in the housing  12  and on its free end, as a valve member  17 , presses against a closing element  18 ; the closing element  18  in turn is braced on a valve seat  19 . 
   A radially extending armature plate  21  is mounted on the other end of the axially oriented armature bolt  16 ; with a plane underside  22 , the armature bolt is spaced apart from a diametrically opposed plane top side  23  of the housing  12  through an air gap  24 , which because of its slight dimensions does not stand out in the drawing. In the pressure regulating valve  11 , the air gap  24  is adjusted by the axial height of an adjusting disk or shim  26 , which is disposed between a reference face  27  of the housing  12  and a diametrically opposed contact face  28  of a valve seat body  29 . 
   Supplying current to the electromagnet  13  causes the armature plate  21  and the armature bolt  16  to be penetrated by magnetic flux lines, as a result of which a magnetic force is operative which presses the valve member  17  against both the closing element  18  and the valve seat  19 . The magnitude of this force is dependent on the size of the air gap  24 . 
   The pressure regulating valve  11  shown in longitudinal section in  FIG. 2 , the parts of which taken over from  FIG. 1  will not be named here again, is provided with a force measuring system  31 , coupled to the armature bolt  16 , and with a travel measuring system  33  having a positioning pin  32 , shown only schematically, and with which pin a spacing  34  between the reference face  27  and an end face  36  of the valve member  17  is ascertained. 
   For ascertaining the spacing  34  for the dimensioning of the axial height of the adjusting disk  26  that is still to be inserted and that is shown in  FIG. 1 , the electromagnet  13  is subjected to a current which corresponds to the rated operating point of the pressure regulating valve  11 . From this basic situation, the armature bolt  16 , in the housing  12  that is fixed in stationary fashion, is displaced counter to the force brought about by supplying current to the electromagnet  13 , until a predetermined contrary force, with which the pressure regulating valve  11  is to close at the rated operating point, is reached. This force is controllable by the force measuring system  31  with high precision. 
   The aforementioned displacement of the armature bolt  16  is effected by the positioning pin  32  of the travel measuring system  33 , which pin rests on the end face  36  of the valve member  17 . 
   Once the predetermined contrary force, controlled by the force measuring system  31 , is reached, the axial spacing  34  between the end face  36  of the valve member  17  and the reference face  27  of the housing  12  of the pressure regulating valve  11  is measured, at the rated operating point of the pressure regulating valve  11 , with high precision by the travel measuring system  33 . 
   Because of the precision measurements of the travel measuring system  33  and of the force measuring system  31  that controls the travel measuring system, the preconditions for high-precision ascertainment of the spacing  34  and of the axial height, which can be derived with it, of the adjusting disk  26  exist, so that thus the pressure of the fuel reservoir which is monitored by the pressure regulating valve  11  can be adhered to within narrow limits. 
   The foregoing relates to a preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.