Patent Abstract:
The electromagnetic valve comprises a cylindrical housing and a solenoid having an axial hole capable of receiving one of the ends of the housing that is associated with a split ring capable of being placed in a first circular recess on the periphery of the housing for extending partially and simultaneously in a second circular recess on the inner surface of the axial hole of the hole forming a port in such a manner as to establish a connection between the housing and the solenoid and the hole forming a port. An elastically compressible intermediate ring is placed around the housing and capable of being compressed between opposing support surfaces.

Full Description:
BACKGROUND OF INVENTION 
     The present invention relates to an electrically operated valve, in particular of the type used in a hydraulic unit mounted in a motor vehicle. 
     The invention also relates to a process for fitting a solenoid on the electrically operated valve, and a process for removing the solenoid from the electrically operated valve. 
     These electrically operated valves generally include a substantially cylindrical housing provided with a collar forming a stop for a solenoid which is mounted at one of the ends of the electrically operated valve. The solenoid is provided with an axial hole receiving this end of the electrically operated valve when these two elements are assembled. The solenoid can thus be axially displaced along this end to abut against this collar. The electrically operated valve also includes first connecting means of the housing to the solenoid when it is in abutment against the collar, and second connecting means of the housing to the inside of a hole forming a port in the hydraulic unit. 
     The invention relates in particular to these first connecting means which simultaneously form means for axial locking of the solenoid in its service position on the valve housing. The electrically operated valve as such will not be described in detail since it is well known to the man skilled in the art. First and second connecting means associated with the housing of an electrically operated valve are known. Two embodiments generally used are illustrated in  FIGS. 1 ,  2  respectively. 
     In  FIG. 1  which shows very diagrammatically an electrically operated valve of the type described in the document EP 0 538 986. The electrically operated valve  1  is shown in its installed position in a hydraulic unit  2 . The details of the inside of the valve are not shown, since they do not directly relate to the invention. The electrically operated valve  1  includes a substantially cylindrical housing  3  one ( 4 ) of the ends of which is shown in  FIG. 1 . A solenoid  5  includes a through axial hole  6  receiving the end  4  of the electrically operated valve  1 . The solenoid  5  is in abutment against a collar  7  provided on the periphery of the housing  3  and is locked there in a service position by means of axial locking means. 
     In the example shown in  FIG. 1 , these means for axially locking the solenoid  5  include a thread  8  at the tip of the end  4  of the housing  3  which co-operates with a nut  9  screwed onto the end  4  and tightened against an end surface of the solenoid so as to bias the end surface opposite to this against the collar  7 . The thread  8 , with the tapping of the nut  9 , forms the first connecting means to connect these two elements together. 
     The housing  3  is provided over a part of its length with a second thread  23  which co-operates with a tapping  24  provided in a hole forming a port  25  in the hydraulic unit  2 . The thread  23 , with the tapping  24 , forms second connecting means to connect the electrically operated valve  1  to the hydraulic unit  2 . The collar  7  has a hexagonal shape in order to allow screwing of the electrically operated valve  1  into the hydraulic unit by means of a tool (not shown). 
     In the example shown in  FIG. 1 , a first sealing ring  26  is arranged in a conical cavity  27  around the opening of the hole forming a port  25  on the face of the hydraulic unit  2 . A second sealing ring  28  and a third sealing ring  29  are arranged in a groove  30 ,  31  respectively on the periphery of the housing  3  of the electrically operated valve  1 . 
       FIG. 2  shows an electrically operated valve  1  which differs from that described with reference to  FIG. 1  only by the fact that it includes another type of means for connecting or axially locking the solenoid  5  relative to the housing  3  of the electrically operated valve  1 . The other elements being the same, they have retained their reference numbers and will not be described further. 
     The axial locking means shown in  FIG. 2  include a flange  10  at one of the ends of the solenoid, this flange being provided with a plurality of through holes  11  receiving a respective fixing screw  12  which can be screwed into a respective tapped hole  13  provided in the hydraulic unit. The flange  10  is thus tightened against the hydraulic unit, biasing the solenoid  5  against the collar  7  of the valve housing  3 . 
     Instead of the flange, lugs could also be used provided with a hole in place of the flange  10 . These lugs could be four in number and uniformly spaced around the periphery of the solenoid  5 . 
     However, these known solutions, in particular for these first connecting means, are bulky and costly to use. Moreover, they require anti-corrosion treatment of the part of the electrically operated valve which is exposed to the environment. 
     SUMMARY OF THE INVENTION 
     The aim of the invention is to remedy these disadvantages by proposing an electrically operated valve provided with connecting means, on the one hand between the solenoid and the housing and on the other between the housing and the hydraulic unit, permitting very simple and inexpensive fitting of the solenoid onto the valve housing, and of the latter onto the hydraulic unit, and a better seal to be obtained rendering the anti-corrosion treatment unnecessary. 
     The object of the invention is an electrically operated valve including a substantially cylindrical housing and a solenoid having an axial hole able to receive one of the ends of the housing, the housing being associated with first connecting means of the housing to the solenoid so as to form an assembly and with second connecting means of the housing to a hole forming a port in an hydraulic unit, characterised by the fact that the first and/or second connecting means include a split ring able to be arranged in a first circular cavity provided on the periphery of the housing to extend partially and simultaneously into a second circular cavity provided on the inside face of the axial hole in the solenoid and/or of the hole forming a port so as to form a connection between on the one hand the housing and on the other the solenoid and/or the hole forming a port, and by the fact that the first and/or the second connecting means are associated with at least one elastically compressible intermediate ring arranged around the housing and able to be compressed between first and second opposed contact surfaces positioned one facing the other, the first and second contact surfaces being provided on the solenoid-housing assembly and/or on this assembly and on the hydraulic unit. 
     In accordance with other characteristics of the invention:
         one of the first and second contact surfaces is provided on the solenoid around the axial hole in this and the other on a collar of the housing;   one of the first and second contact surfaces is provided on a collar of the housing able to be introduced into the hole forming a port in the hydraulic unit and the other on an annular shoulder in the hole forming a port;   a second elastically compressible intermediate ring is arranged around the housing and able to be compressed between first and second opposed contact surfaces positioned one facing the other, one of the first and second contact surfaces being provided on the solenoid, around the axial hole in this, and the other on the hydraulic unit, around the hole forming a port in this;   the first circular cavity is defined on one of the faces of the collar of the housing;   the first circular cavity is defined by a groove on the peripheral face of the collar of the housing;   the locking means are associated with an elastically compressible intermediate ring arranged around the housing, between the collar and an annular contact surface around the axial hole in the solenoid;   the split ring is a metal ring;   the split ring has a circular section;   the thickness of the wall separating the second groove from the corresponding end face of the solenoid is sufficiently thin to allow removal of the solenoid by forcing it outwardly so as to deform the wall by means of the split ring;   the end surface of the solenoid turned towards the collar is generally in the form of a truncated cone and able to co-operate with a wedge;   the solenoid is covered on all sides by a protective casing;   the casing is made of a malleable a magnetic metal and has a generally cylindrical tubular shape, closed at one of its ends and crimped on the solenoid at the opposite end;   the casing is made of a plastics material over-moulded on the solenoid.       

     In accordance with the process of the invention for fitting a solenoid to the valve defined above, the split ring is placed in one or the other of the first and second grooves on the housing or on the inside face of the axial hole in the solenoid, respectively, this axial hole is aligned with the end of the valve housing, this end is introduced into the axial hole and the solenoid is pushed to axially displace it towards the collar forming a stop on the housing, deforming the split ring elastically in a radial direction to retract it into the groove until the first and second grooves come opposite each other to allow the split ring to readopt its original shape extending simultaneously into the two grooves. 
     In accordance with another characteristic of fitting, the intermediate ring is compressed to eliminate any axial play of the solenoid on the housing when the first and second grooves are arranged opposite each other. 
     In accordance with yet another characteristic of fitting, the elastically compressible intermediate ring is sufficiently compressed between the collar and an annular contact surface on an end face of the solenoid to simultaneously form a means for locking this in rotation around the valve housing. 
     In accordance with the process of the invention for removal of a solenoid from the valve defined above, a tool in the form of a wedge is introduced between the end surface of the solenoid and the hydraulic unit and the wedge is driven in horizontally to create a vertically acting force component to displace the solenoid outwardly deforming the wall by means of the split ring which is axially locked in the first and second grooves. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Other characteristics and advantages of the invention will become apparent from the following description of a non-limiting embodiment of the invention, with reference to the attached figures in which: 
         FIGS. 1 and 2  are views in diagrammatic axial section of two known embodiments described in the introduction; 
         FIG. 3  is a view in diagrammatic section showing an embodiment of the invention; 
         FIG. 4  is a view in section to a larger scale of some details circled in  FIG. 3 ; 
         FIG. 5  is a view in plan of a split ring of the axial locking means in accordance with the invention; 
         FIG. 6  is a very diagrammatic view of removal of the solenoid from the housing of the electrically operated valve; 
         FIG. 7  is a view in diagrammatic section showing a second embodiment of the invention; 
         FIG. 8  is a view in diagrammatic section showing a modification with a combination of the first and second embodiment of the invention; 
         FIG. 9  is a partial view in diagrammatic section showing a modification of the second embodiment. 
     
    
    
     In the figures, identical or equivalent elements will bear the same reference signs. 
     DETAILED DESCRIPTION OF INVENTION 
     As in  FIGS. 1 and 2 , the electrically operated valve  1  of  FIG. 3  is shown in its position installed in a hydraulic unit  2 . Here too, the details of the inside of the valve are not shown since they do not directly relate to the invention. The electrically operated valve  1  includes a substantially cylindrical housing  3  one ( 4 ) of the ends of which is shown in  FIG. 3  inserted in the axial hole in the solenoid  5 , while its opposite end, which carries a thread  23 , is screwed into the hole forming a port  25  in the hydraulic unit  2 . 
     The solenoid  5  is in abutment against a collar  7  of hexagonal shape provided on the periphery of the housing  3  and is locked there in a service position by means of first connecting means which also form axial locking means. 
     In accordance with an important characteristic of the invention, these first means for connecting the solenoid  5  to the housing  3  of the electrically operated valve  1  so as to form an assembly. These first connecting means include a split ring  14  made from a slightly elastic material. This ring is able to extend into a first circular cavity in the form of a groove  15  on the periphery of the housing and partially and simultaneously also into a second circular cavity in the form of a groove  16  provided on the inside face of the axial hole in the solenoid  5  and which can be arranged opposite the groove  15 . 
     The respective locations of these two grooves  15 ,  16  are suited in height so that the two grooves are positioned one facing the other when the solenoid  5  comes into abutment against the collar  7 . The split ring  14  then provides the connection between the solenoid and the housing, and in this manner axial locking of the solenoid  5  is also obtained. 
     In order to offer sufficient resistance to shear forces, the split ring  14  is preferably made of metal. This ring preferably has a circular section, which facilitates fitting, but it can also have a rectangular section. 
     In this last case, the edge at the tip of the end  4  of the housing  3  is advantageously bevelled to facilitate fitting. 
     Before fitting, the split ring  14  has an external diameter greater than the diameter of the axial hole  6  in the housing  3 , in order to be able to extend simultaneously into the first and second grooves  15 ,  16  after the fitting operation. Moreover, the depth of one of the first and second grooves  15 ,  16  is at least equal to the thickness of the ring in order to allow this to be retracted elastically into it during the fitting operation, while to obtain an axial locking effect, the depth of the other groove ( 15  or  16 ) is less than the thickness of the ring so that the outer periphery of the ring  14  can project from the groove of lesser depth to thus penetrate slightly into the other groove when the two grooves  15 ,  16  are placed one opposite the other and the ring is biased towards the bottom of the groove of lesser depth in the manner which will be explained below. 
     To fit the solenoid  5  on the valve housing  3 , it is only necessary to place the split ring  14  in the one of the first and second grooves  15 ,  16  which has a depth at least equal to the thickness of the split ring  14 , to align this axial hole with the end  4  of the valve housing  3 , to introduce this end into the axial hole and to push the solenoid to displace it axially towards the collar  7  forming a stop on the housing. 
     In the case in which the first groove  15  on the housing  3  has a depth suited to receive the split ring  14  at the start of the fitting operation, the ring will be elastically radially inwardly deformed in it to be retracted entirely into this groove  15  when it comes into contact with the edge around the axial hole  6  in the solenoid  5 . 
     In the case in which the second groove  16  in the axial hole  6  in the solenoid  5  has a depth suitable to receive the split ring  14  at the start of the fitting operation (see  FIGS. 3 and 4 ), the ring will be elastically radially outwardly deformed in it to be entirely retracted into this groove  16  when it comes into contact with the peripheral edge of the end  4  of the housing  3 . 
     In the one case as in the other, the split ring will remain retracted into the corresponding groove  15  or  16  until the two grooves  14 ,  15  are arranged one opposite the other. At this moment, the split ring  14  will readopt its original shape to extend simultaneously into the two grooves. 
     In order to eliminate any play which could remain between the end face  17  of the solenoid  5  and the collar, in accordance with an important characteristic of the invention, the first connecting means are associated with an elastically compressible intermediate ring  18  arranged around the housing  3  of the electrically operated valve, between a first contact surface  32  on the collar  7  and a second opposed annular contact surface  19  on this end  17  of the solenoid, around the axial hole  6 . 
     On fitting of the solenoid  5  on the valve housing  3 , this elastically compressible intermediate ring  18  is compressed so as to eliminate any play in the first connecting means by biasing the solenoid outwardly. This biasing will have the effect of one of the edges defining the second groove  16  (see  FIG. 4 ) pushing the split ring radially towards the inside of the first groove until it comes into abutment against the bottom of this. In this position, the solenoid  5  is entirely axially locked. 
     The elastically compressible intermediate ring  18  is advantageously sufficiently compressed between the first contact surface  32  of the collar  7  and the second contact surface  19  of the solenoid  5  to simultaneously form a means for locking the solenoid in rotation around the valve housing  3 . This ring  18  is preferably made of a material allowing the ring to also form an efficient seal. Thus, the intermediate elastic ring  18  has three different functions: taking up play, locking in rotation and sealing. 
     In order to be able to change the solenoid  5  should there be need, it is necessary to be able to remove it from the valve housing  3 . To allow removal, the wall  20  in the solenoid separating the second groove  16  from the annular contact surface  19  is sufficiently thin for removal of the solenoid to be able to be accomplished by forcing the solenoid outwardly so as to deform the wall by means of the split ring. 
     This removal is illustrated in  FIG. 6  which shows the introduction of a tool in the form of a wedge  21  between the end surface  17  of the solenoid  5  and the hydraulic unit  2 . When this wedge is driven in the direction of the horizontal arrow A, a force component will act in the direction of the vertical arrow B to displace the solenoid outwardly, deforming the wall  20  by means of the split ring  14  which is axially locked in the first and second grooves  15 ,  16 . 
     In order to facilitate this removal in case of changing the solenoid, the end face  17  of the solenoid  5  is preferably generally in the form of a truncated cone to offer a better contact surface to the upper inclined surface on the wedge  21  shown in  FIG. 6 . 
     The solenoid  5  is advantageously provided with a protective casing  22  which encloses it on all sides, leaving free only a zone around the axial hole  6  and which, due to the presence of the intermediate ring  18 , makes the whole assembly sealed so that no anti-corrosion treatment of the metal surfaces is any longer necessary. 
     This casing  22  can be made of a malleable amagnetic metal and have a generally cylindrical tubular shape, closed at one of its ends and crimped on the solenoid  5  at the opposite end. 
     By way of modification, this casing can be made of a plastics material quite simply over-moulded on the solenoid. 
       FIGS. 7 and 8  show an embodiment in accordance with the invention of the second connecting means of the housing  3  to the hydraulic unit  2 . 
     In the embodiment shown in  FIG. 7 , the first means for connection between the housing and the solenoid are conventional and correspond to those shown in  FIG. 1 , while the second connecting means of the housing  3  to the hydraulic unit  3  include similar elements to those described with reference to the first connecting means, such as shown in  FIGS. 3 and 4 . 
     In this embodiment, the second connecting means include a split ring  14  arranged in a first circular cavity  33  provided on the periphery of the housing  3  and more precisely on the upper face of a collar  34  of the latter. A second circular cavity  35  in the form of a groove is provided on the inside face of the hole forming a port  25 . 
     The hole forming a port  25  has a larger diameter close to its opening to the outside face of the hydraulic unit so as to define an annular shoulder  36  inside this hole. 
     The collar  34  is introduced into this hole and defines on its lower face a first contact surface  37  for an elastically compressible intermediate ring  18  arranged around the housing  3 . A second contact surface  38  opposite to the first is defined by the shoulder  36  inside the hole forming a port  25  in order to compress the ring  18  between them on introduction of one of the ends of the housing  3  into this hole forming a port. 
     The ring  14  is suitable to be partially housed in the second circular cavity inside the hole forming a port and simultaneously in the first circular cavity  33  on the upper face of the collar  34 , so as to connect the housing  3  to the hydraulic unit  2  while compressing the intermediate ring  18 . 
     In this embodiment, the solenoid  5  rests directly against the outside face of the hydraulic unit  2 , with interposition of a second elastically compressible intermediate ring  18 ′. This second ring  18 ′ is arranged around the housing and compressed between first and second opposed contact surfaces facing one another, the first being provided on the solenoid  5  around the central hole  6  in this, and the second on the hydraulic unit  2 , around the hole forming a port  25  in this. 
     A more compact structure is thus obtained than that of a conventional electrically operated valve after fitting to a hydraulic unit. 
       FIG. 8  shows another embodiment of the electrically operated valve in accordance with the invention in which the first connecting means of the solenoid  5  to the housing  3  of the electrically operated valve  1  are the same as those described with reference to  FIG. 3 , while the second connecting means of the housing  3  to the hydraulic unit  2  are the same as those described with reference to  FIG. 7 . This is a particularly advantageous combination of these first and second connecting means in accordance with the invention. 
     Lastly,  FIG. 9  shows a modification of the embodiments of  FIGS. 7 and 8 , in which the first circular cavity is defined by a groove  33 ′ on the peripheral face of the collar  34  of the housing  3 . 
     Of course, the invention is not limited to the examples shown and described and the man skilled in the art will be able to make modifications to them without thereby departing from the scope of the invention.

Technology Classification (CPC): 5