Control valve and method for its production

Abstract

The invention relates to a control valve for influencing the action of a pressure medium on a camshaft adjuster of an internal combustion engine. A control valve of said type comprises a valve housing ( 72 ), in which a displaceable control piston ( 71 ) is arranged in a blind bore. According to the invention, the valve housing ( 72 ) is produced with a through bore ( 73 ) instead of a blind bore, into which through bore ( 73 ) a housing insert ( 79 ) is clipped into a groove ( 80 ). The housing insert can serve to support a pressure spring ( 76 ), and can also additionally have recesses, in the region of which the housing insert ( 79 ) serves to form a port, for example to a tank T.

1 . Control valve for influencing the action of a pressure medium on a camshaft adjuster of an internal combustion engine, having 
 a valve housing ( 72 ),    a control piston ( 71 ) which is arranged in the valve housing ( 72 ) and is axially displaceable under the action of a spring element (pressure spring  76 ), and    a pressure medium port (P), a tank port (T) and two working ports (A, B),    wherein, for one axial position of the control piston ( 71 ), a first working port (A) can be connected to the or a tank port (T 2 ), and the second working port (B) can be connected to the pressure medium port (P), while for another axial position of the control piston ( 71 ), the second working port (B) can be connected to the or a tank port (T 1 ) and the first working port (A) can be connected to the pressure medium port (P), characterized in that the spring element (pressure spring  76 ) is supported, by means of the foot point ( 78 ) situated at the opposite side from the control piston ( 71 ), on a housing insert ( 79 ).    
   
   
       2 . Control valve according to  claim 1 , characterized in that the housing insert ( 79 ) has recesses ( 88 ), through which the pressure medium can pass out of the control valve ( 70 ) in order to form a port (T 2 ).  
   
   
       3 . Control valve according to  claim 2 , characterized in that the recesses ( 88 ) extend inwards from an outer edge ( 85 ) of the housing insert ( 79 ).  
   
   
       4 . Control valve according to one of the preceding claims, characterized in that the housing insert ( 79 ) is clipped into the valve housing ( 72 ).  
   
   
       5 . Control valve according to  claim 4 , characterized in that, in longitudinal section, the housing insert ( 79 ) is approximately in the form of the longitudinal section of a hat or of a pot, and the “brim” ( 84 ) of the hat or the edge ( 85 ) of the pot is clipped into a groove ( 80 ) of an inner lateral surface ( 81 ) of the valve housing ( 72 ).  
   
   
       6 . Control valve according to  claim 5 , characterized in that the mid-region ( 86 ) of the hat-shaped housing insert ( 79 ) is conical, said mid-region ( 86 ) adjoining the brim ( 84 ).  
   
   
       7 . Control valve according to one of the preceding claims, characterized in that the diameter of a bore ( 73 ) for holding the housing insert ( 79 ) approximately corresponds to the diameter of the region for holding the control piston ( 71 ) in an axially displaceable fashion.  
   
   
       8 . Control valve according to one of the preceding claims, characterized in that the housing insert ( 79 ) forms a stop ( 83 ) for the control piston ( 71 ), in order to predefine an axial end position of the control piston ( 71 ).  
   
   
       9 . Control valve according to one of the preceding claims, characterized in that the control valve ( 70 ) is suitable for being integrated into a camshaft.  
   
   
       10 . Method for producing a control valve for influencing the action on a camshaft adjuster of an internal combustion engine, in particular a control valve according to one of  claims 1  to  9 , characterized by the following method steps: 
 a) forming a bore ( 73 ) in the valve housing ( 72 ), said bore ( 73 ) being at least of a length which permits it to hold both a control piston ( 71 ) and also a housing insert ( 79 ),    b) forming a groove ( 80 ) in the bore ( 73 ) of the valve housing ( 72 ),    c) radially compressing a housing insert ( 79 ),    d) inserting the housing insert ( 79 ), in the radially compressed state, into the bore ( 73 ) of the valve housing ( 72 ) and    e) radially expanding the housing insert ( 72 ) in such a way that the radially outer edge ( 85 ) of the housing insert ( 79 ) is received in the groove ( 80 ) of the valve housing ( 72 ).    
   
   
       11 . Method according to  claim 10 , characterized in that the bore ( 73 ) is formed in the valve housing ( 72 ) in the form of a through bore.  
   
   
       12 . Method according to  claim 10  or  11 , characterized in that a housing insert ( 79 ) is produced in the form of a “hat”, with a conical mid-region ( 86 ), and the housing insert ( 79 ) is radially elastically expanded and compressed by changing the opening angle ( 90 ) of the conical mid-region ( 86 ).  
   
   
       13 . Method according to  claim 12 , characterized in that, in order to insert the housing insert ( 79 ) into the valve housing ( 72 ), the housing insert ( 79 ) is held in a tool ( 91 ) such that the opening angle ( 90 ) of the conical mid-region ( 86 ) is reduced.