Abstract:
A valve assembly, in particular for a hydraulic vehicle brake system with traction control, having at least one, preferably electromagnetically actuatable valve, which receives valve components in a valve housing and is retained by fastening means by nonpositive and/or positive engagement in a receiving bore of a valve block. The valve block, at least in the region of the receiving bore, comprises thermoplastic, and the fastening means have at least one retracted region on the radially outer circumference of the valve housing or of a valve holder that retains the valve housing in the receiving bore, into which region plastic rendered molten by heating and ensuing insertion of the valve and/or of the valve holder into the receiving bore can flow, and after cooling of the thermally deformed plastic a positive-engagement connection can develop between the valve housing and the receiving bore or the valve holder and the receiving bore.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a 35 USC 371 application of PCT/DE 00/03815 filed on Oct. 28, 2000. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention is based on a method for producing a valve assembly, in particular for a hydraulic vehicle brake system with traction control and to a valve assembly produced by the method. 
   2. Description of the Prior Art 
   From International Patent Disclosure WO 99/44872, an electromagnet valve is known, having a valve housing that receives valve components and is secured in a stepped bore of a thermoplastic valve block. The diameter of the valve housing is reduced in the joining direction by a shoulder, which is adjoined by a recess embodied as an annular groove. Moreover, the material comprising the valve block has a lesser material hardness than the material of the valve housing. During the insertion motion of the electromagnet valve into the stepped bore of the valve block, the shoulder of the valve housing takes on the function of a calking die, which plastically displaces the softer material of the valve block positively into the annular groove of the valve-housing. This creates a positive-engagement connection between the valve housing of the electromagnet valve and the valve block. 
   A brake force regulator of twin-design is also known from International Patent Disclosure WO 95/14594; it has two regulating valves, whose housings are embedded in a plastic valve block in the production of the valve block. A magnet valve is also secured to the valve block by calking. 
   SUMMARY OF THE INVENTION 
   The method of the invention has the advantage of the prior art that the in the assembly of the valves, no impact loads that could damage the valve components or the valve block occur in the receiving bores. Because of the melting of the valve block, made of thermoplastic, in the region of the inner wall of the receiving bore as a result of the previously heated and then inserted valve, a readily flowing viscous melt is created, which does not penetrate into even tiny indentations in the valve housing or the valve holder. Since moreover the strength properties of the melted and re-hardened plastic are not significantly different from those of untreated plastic, a reliable positive-engagement connection is assured. This makes an especially gentle installation of the valves possible. 
   A valve assembly produced according to the method of the invention provides that the retracted region has knurled features and/or cross-hatched knurled features, embodied on the outer circumference of the valve housing, and additionally has two annular grooves, spaced apart from one another in the axial direction, of which one annular groove is disposed in the region of a radially outer shoulder that reduces the outer diameter of the valve housing, as viewed in the joining direction, and that is braced against a first radially inner shoulder of the receiving bore, and that a sealing ring, preferably embodied as an O-ring, is fastened in an annular chamber that is defined in the radial direction by the valve housing and the inner wall of the receiving bore of the valve block and in the axial direction by the inner wall of the receiving bore of the valve block and by the valve holder or the valve housing, or only by the valve housing. In that case it suffices to bring the outer region of the valve holder or valve housing to the melting temperature of the plastic, while the valve components located farther inside are exposed to a lesser temperature and the valve can therefore be installed still more gently. Furthermore, the encircling knurled features make a relatively large-area attachment of the valve holder or valve housing in the receiving bore possible. Moreover, by means of the fastened sealing ring, a pressure- and fluid-tight sealing off of the valve in the valve block is attained in a simple way. 
   By the provisions recited in the dependent claims, advantageous refinements of and improvements to the invention defined by claim  2  are possible. 
   DRAWINGS 
   Exemplary embodiments of the invention are shown in the drawings and explained in further detail in the ensuing description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention are described in further detail herein below, with reference to the drawings, in which: 
       FIG. 1  shows a side view of a valve assembly of the invention in a preferred embodiment; 
       FIG. 2  is a sectional view taken along the line II—II in  FIG. 1 ; and 
       FIGS. 3 and 4 ;  5  and  6 ; and  7  and  8 , respectively, show further embodiments in corresponding views. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the exemplary embodiment of  FIGS. 1 and 2 , the valve assembly  1  of the invention is intended for instance for a hydraulic vehicle brake system with traction control and includes a valve block  2  which essentially entirely comprises thermoplastic and in which receiving bores  4  are embodied for receiving preferably electromagnetically actuatable valves, of which the valve shown in  FIG. 1  is for instance a 2/2-way outlet valve  6  that in its currentless basic position blocks the return flow of brake fluid from a wheel cylinder to a return pump. The communication with the return pump is established by an outlet conduit  8  extending transversely in the valve block  2  and discharging into an annular conduit  10  between a valve housing  12  that receives valve components and an inner wall  14  of the receiving bore  4 . The valve housing  12  preferably has a larger-diameter valve housing head  16 , in which a magnet coil and a pole core, for instance, are accommodated, and a smaller-diameter valve housing foot  18 , which surrounds a valve seat, for instance. Correspondingly, the diameter of an upper portion  20  of the receiving bore  4  that receives the valve housing head  16  is larger than a lower portion  22 . 
   As can be seen from  FIG. 2 , the upper portion  20  of the receiving bore  4  is also stepped multiple times, and because of a first radially inner shoulder  24  and a second radially inner shoulder  26  adjoining it in the joining direction of the valve  6  and a third radially inner shoulder  28 , the diameter decreases in stages. The shoulders  24 ,  26 ,  28  serve to support the valve  6 , a valve holder  30 , and a sealing ring, embodied as an O-ring  32 , in the receiving bore  4 ; these components together make up a preassembled unit  34 , shown in FIG.  2 . 
   The bushlike valve holder  30  is slipped onto the valve housing head  16  and surrounds it axially almost completely; only a lower portion  36  of the valve housing head  6  that is only insignificantly longer than the diameter of the cross section of the O-ring  32  protrudes. The valve holder  30 , on its head end, has a radially inner shoulder  38 , which fits over the edge of the end face  40  on the head end of the valve housing  12  in the preassembled state. The radially outer circumferential face  42  of the valve housing head  16  is cylindrically smooth and can therefore be produced simply and economically. 
   As best seen from  FIG. 1 , knurled features  46  and cross-hatched knurled features  48  are embodied on the outer circumference  44  of the valve holder  30 . In addition, two annular grooves  50 ,  52  spaced apart from one another in the axial direction are provided, of which one annular groove  52  is disposed in the region of a radially outer shoulder  54  that reduces the outer diameter of the valve holder  30  in the joining direction. The O-ring  32  is radially stretched and is slipped, in the preassembled state, onto the lower portion  36  of the valve housing head  16  protruding from the foot end  56  of the valve holder  30  until it rests on the foot-end end face  58  of the valve holder  30 . 
   For installation in the receiving bore  4 , the above-described preassembled unit  34  is heated and forced or inserted into the receiving bore  4  until the radially outer shoulder  54  of the valve holder  30  strikes the first radially inner shoulder  24  of the receiving bore  4 , and the lower portion  36  of the valve housing head  16 , protruding from the valve holder  30 , strikes the third radially inner shoulder  28  of the receiving bore  4 . A disklike upper end face  60  of the valve holder  30  is flush with the edge of the receiving bore  4 . 
   Since the inside diameter of the upper portion  20 , oriented toward the valve holder  30 , of the receiving bore  4  is only insignificantly greater than the outside diameter of the valve holder  30 , the outer circumference  44  of the valve holder  30  rests in heat-transferring fashion on the inner wall  14  of the receiving bore As a result, the thermoplastic of the inner wall  14  of the receiving bore  4  is melted and can flow into the retracted regions formed by the two annular grooves  50  the knurled features  46 , and the cross-hatched knurled features  48 . After the accordingly thermally deformed plastic has cooled down, a positive-engagement connection exists between the valve holder  30  and the receiving bore  4 . 
   As a result of the positive engagement, the valve housing head  16  is braced between the radially inner shoulder  38  of the valve holder  30  and the third radially inner shoulder  28  of the receiving bore  4 . Moreover, the O-ring  32  is thus clamped in an annular chamber  62 , which is defined in the axial direction by the bottom end face  58  of the valve holder  30  and the second radially inner shoulder  26  of the receiving bore  4  and in the radial direction by the lower portion  36 , protruding from the valve holder  30 , of the valve housing head  16  and the part  64  of the inner wall  14  of the receiving bore  4  that adjoins the first radially inner shoulder  24  in the joining direction. The O-ring  32  serves to seal off the annular conduit  10 , communicating with the outlet conduit  8  in the valve block, in pressure- and fluid-tight fashion toward the head of the valve  6 . 
   Since the valve housing head  16  is preferably essentially the same length as the valve holder  30 , the length of the lower portion  36 , protruding from the valve holder  30 , of the valve housing head  16  is equivalent to that of the radially inner shoulder  38  of the valve holder. Then the O-ring  32  can utilize the annular chamber  62 , which is created by the axial offset of the valve housing  12  as a result of the radially inner shoulder  38  on the valve holder  30 , so that an axially compact structure is obtained, and the upper portion  20  of the receiving bore  4 , which receives the valve housing head  16 , can be relatively short. 
   In a second embodiment, shown in  FIGS. 3 and 4 , the O-ring  32   a  is fastened in an annular chamber  62   a , which is defined in the axial direction by an outer shoulder  66   a , embodied on the lower portion  36   a  of the valve housing head  16   a  that protrudes from the valve holder  30   a , and by the third radially inner shoulder  28   a  of the receiving bore  4   a . In the radial direction, this annular chamber  62   a  is defined on the one hand by the valve housing head  16   a , whose diameter at this point is reduced by the shoulder  66   a , which corresponds in its depth to the cross section of the O-ring  32   a , and on the other hand by the part  68   a  of the inner wall  14   a  of the receiving bore  4   a , which part adjoins the second radially inner shoulder  26   a  in the joining direction and at this point has essentially the same inside diameter as the valve holder  30   a . As a result, the position of the O-ring  32   a  is shifted some distance farther inward radially. As a consequence, the total axial area on which the liquid pressure prevailing in the annular conduit  10   a  is exerted, is reduced by the area of the foot-end end face  58   a  of the valve holder  30   a , so that the total pressure force acting on the valve holder  30   a  in the axial direction counter to the positive-engagement anchoring is reduced. 
   In a distinction from the first and second embodiments, in a third embodiment shown in  FIGS. 5 and 6  the valve holder  30   b  has no radially inner shoulder; instead, it has a continuously smooth inner bore, making it simple and economical to produce. In addition, the valve housing  12   b , on its outer circumference, has a flange ring  70   b , which is fastened between the bottom end face  58   b  of the valve holder  30   b  and the third-radially inner shoulder  28   b  of the receiving bore  4   b . Finally, the diameter of the receiving bore  4   b  is reduced further by means of a fourth radially inner shoulder  72   b  that adjoins the third radially inner shoulder  28   b  in the joining direction. The O-ring  32   b  is received in an annular chamber  62   b , which is defined in the axial direction by a lower flange face  76   b  and by the fourth radially inner shoulder  72   b  of the receiving bore  4   b . In the radial direction, this annular chamber  62   b  is defined by the reduced-diameter valve housing foot  18   b  and by the part  78   b  of the inner wall  14   b  of the receiving bore  4   b  that adjoins the third radially inner shoulder  28   b  in the joining direction. As a result, the location of the O-ring  32   b  is shifted still further inward radially by some distance, and therefore the total pressure force exerted on the valve holder  30   b  in the axial direction is reduced further. 
   Instead of providing a valve holder, the knurled features  46   c ,  48   c  and the two annular grooves  50   c  can be embodied directly on the outer circumference  80   c  of the valve housing  12   c , as is shown for the fourth embodiment in  FIGS. 7  and  8 . The outer contour of the valve housing head  16   c  is then like that of the valve holder of the embodiments described above. In this case, the O-ring  32   c  is received in a further annular groove  82   c  , which on the outer circumference  80   c  of the valve housing head  16   c  is adjacent in the joining direction to the two annular grooves  50   c  that provide the positive engagement. Since a valve holder that surrounds the valve housing  12   c  is dispensed with here, the diameter of the valve housing head  16   c  can be selected as correspondingly small, which has a favorable effect in terms of the space conditions in the valve block  2   c.    
   The foregoing relates to preferred exemplary embodiments 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.