Abstract:
Hydraulically or pneumatically controlled seat valve ( 2 ), in particular a pressure control valve, having a valve seat ( 10 ) formed in a base part ( 4 ) which cooperates with the sealing surface of a valve body ( 8 ) displaceably disposed in a cover part ( 6 ), wherein the base part ( 4 ) and the cover part ( 6 ) are connected to each other, the base part ( 4 ) having an at least sectionally circumferential collar ( 18 ) which faces radially outwardly for mounting the seat valve ( 2 ) to a further component ( 60 ), in particular to a housing, using a welded joint.

Description:
[0001]    This application claims Paris Convention priority of DE 102 59 884.4 filed Dec. 20, 2002 the complete disclosure of which is hereby incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention concerns a hydraulically or pneumatically controlled seat valve, in particular, a pressure control valve, comprising a valve seat formed in a base part which cooperates with a sealing surface of a valve body which is displaceably disposed in a cover part, wherein the base part and the cover part are connected to each other.  
           [0003]    A valve of this type is disclosed e.g. in EP 0 463 289 B1. The valve has a base part of aluminum and a cover part of plastic material. The base part and the cover part are connected to each other via a jointed-flange connection. Towards this end, the base part of aluminum has a circumferential flanged edge which is flanged about an edge section of the cover part.  
           [0004]    DE 201 08 856 U1 discloses a valve of this type whose base part and cover part are connected to each other via a locking connection.  
           [0005]    The conventional valves may be disposed e.g. in an oil filter housing to form a filter bypass valve. When the oil filter is blocked, the valve opens to permit passage of unfiltered oil from the raw to the clean side of the filter, without being filtered. This ensures that a connected unit, such as e.g. a combustion engine, is supplied with oil even when the oil filter is blocked. Mounting of the valves, which are introduced in a housing through a pressing operation, is difficult. It is in particular problematic to guarantee uniform quality of the pressing operation and positionally accurate mounting of the valve in the housing under mass production conditions.  
           [0006]    It is therefore the underlying purpose of the present invention to facilitate mounting of a valve of this type and to permit permanent positionally accurate installation of the valve in a housing.  
         SUMMARY OF THE INVENTION  
         [0007]    This object is achieved in accordance with the invention in that the base part comprises an at least sectionally circumferential collar which faces radially outwardly and with which the seat valve can be mounted to a further component, in particular to a housing, via a welded joint.  
           [0008]    Provision of a collar on the base part has the advantage that a reliable connection between the seat valve and a further component, e.g. a housing, is particularly simple. The proposed collar can be formed in one piece with the base part and be produced together with the base part e.g. through injection molding. Abutment of the collar on a section of the component to which or in which the valve is to be mounted, forms an exactly geometric plane of reference. This ensures that the valve assumes a defined position relative to the component and can be fixed in an exact position. Automated introduction of the valve to a component is also facilitated, since the valve can be initially inserted loosely into the component and does not have to be simultaneously pressed into a component opening with force, as is required e.g. in DE 201 08 856 U1. In contrast thereto, the valve is first precisely positioned and then is connected to the corresponding component.  
           [0009]    Mounting of the valve by means of a welded joint ensures particularly reliable and permanent support of the valve on or in its installed location. Moreover, control of the process-relevant parameters is facilitated by welding, compared to a pressing operation.  
           [0010]    When plastic material is used for the base part, cover part and valve body, the individual components can be produced in a particularly simple and inexpensive fashion. Moreover, disposal and/or recycling of the inventive seat valve are simple and effective.  
           [0011]    The base part, cover part, and valve body are preferably made from the same plastic material. This ensures that the above-mentioned components of the seat valve have uniform properties, which is important e.g. in view of heat expansion when used in high-temperature surroundings. The base part, cover part and valve body can be made from polyamide, which is resistant to hydrolysis and oil. The use of the same plastic material also facilitates disposal and recycling of the seat valve.  
           [0012]    The collar preferably has an annular surface. This annular surface forms a stop which can cooperate with a corresponding receptacle e.g. in a housing to exactly define the installation position of the seat valve. Structuring the collar as an annular surface is particularly advantageous to form a fluid-tight connection e.g. to a housing.  
           [0013]    In a particularly advantageous fashion, the base part and/or the cover part are substantially rotationally symmetrical. The use of a collar which is mounted to the base part and is formed as an annular surface corresponding to the rotational symmetry of the base part, permits connection of the collar of the seat valve to a further component by rotational welding. This provides a particularly reliable and simple connection between the seat valve and e.g. a housing.  
           [0014]    In an embodiment of the invention, the collar has a thickening to facilitate the welded joint. The collar serves not only to geometrically position the seat valve but also as material storage for producing the welded joint to mount the seat valve to a further component. The further component is e.g. also formed from plastic material, preferably from the same plastic material as the base part, such that the collar of the base part and the further component can be connected through welding without using any additional material. Suitable welding methods are e.g. vibration, rotational, ultrasonic, or laser welding methods.  
           [0015]    In one embodiment of the invention, the cover part has locking sections which extend parallel to the incoming flow direction of the seat valve, wherein the front sides of the locking sections facing the flow direction are bevelled and the front sides facing away from the incoming flow direction are oriented perpendicular to the incoming flow direction. This embodiment of the locking sections facilitates the joining process between the base part and cover part, since the bevelled front sides of the locking sections permit gradual widening of the sections of the cover part connected to the locking sections during joining to the base part. The perpendicular orientation of the front sides facing away from the flow direction produces an undercut which reliably prevents release of the cover part from the base part.  
           [0016]    In one embodiment of the invention, the base part has an at least sectionally circumferential bridge which extends radially outwardly and cooperates with front sides of the locking sections of the cover part which are oriented perpendicular to the incoming flow direction. This bridge forms the counter piece of the above-described undercut of the locking sections to prevent release of the cover part from the base part.  
           [0017]    The base part and cover part preferably have mutually facing contact surfaces which are oriented substantially perpendicular to the incoming flow direction of the seat valve. These contact surfaces ensure exact mutual positioning of the base part and cover part such that the outer dimensions of the seat valve can vary only within a very narrow tolerance range. The mutually parallel contact surfaces may be formed on the base part e.g. by a correspondingly shaped shoulder and on the cover part e.g. by wall sections next to the locking sections to ensure that the base part and the cover part can abut each other over a large contact region. This ensures that the base part and cover part remain in a relative position defined by the contact surfaces even under pressure loads from the outside, thereby preventing setting or creeping processes.  
           [0018]    In a further embodiment of the invention, the base part has locking receptacles for the locking sections of the cover part, wherein the receptacles are formed from wall sections which comprise a contact surface described above, joining flank surfaces which are adapted to the shape of the locking sections, and a joining bridge surface of a bridge, described above, which faces the front sides of the locking sections oriented perpendicular to the incoming flow direction. The contact surface, the flank surfaces and the bridge surface form a receiving space for the locking sections of the cover part. This receiving space is adapted to the geometry of the locking sections to provide a particularly reliable and stable connection between the base part and the cover part. The merging wall sections of the receiving space effect material continuity which is advantageous for the production of the base part using injection molding.  
           [0019]    In accordance with an additional further development of the invention, the cover part has an at least sectionally circumferential shoulder which is radially inwardly offset and is suited for abutment on a further component, in particular, on a housing. The shoulder permits exact positioning of the cover part relative to the further component despite the unavoidable tolerances of the locking connection to the base part of the seat valve.  
           [0020]    The shoulder is preferably disposed between a cover part section on the incoming flow side and a cover part section on the outgoing flow side, wherein the outer dimensions of the cover part on the incoming flow side are larger than the outer dimensions of the cover part on the outgoing flow side.  
           [0021]    This particular embodiment allows the valve cover to be secured on a further component via the shoulder when fluid flow acts on the valve body, displaceably disposed in the cover part. The force generated by the fluid flow is thereby passed through the shoulder into the housing, after transmission through the valve body and the cover part. The forces are not passed via the locking sections of the cover part, via the locking receptacles of the base part, or via the base part, thereby load-relieving the locking connection. The locking connection may therefore be of correspondingly small size and design. This is advantageous in that material can be saved and the base part and cover part can be easily locked without requiring great force.  
           [0022]    For a reliable load passage of the produced forces, at least sections of the shoulder are advantageously structured as an annular surface, which is oriented perpendicular to the flow direction of the seat valve. This arrangement also ensures that the position of the cover part relative to a further component is defined with particular precision.  
           [0023]    In an additional further development of the invention, the valve body is guided in a cylindrical guidance which is formed in the cover part and which is open at the front side. A guidance of this type is known in principle from the above-mentioned EP 0 463 289 B1. The cylindrical guidance therein is, however, closed and dirt particles in the fluid may collect therein. Such a collection is effectively prevented by the open cylindrical guidance. This is particularly advantageous when the seat valve is used as a pressure control valve in oil filter arrangements.  
           [0024]    The base part and the cover part advantageously have a cylindrical outer shape, at least in the region where their contact surfaces abut. This embodiment permits particularly easy insertion of the seat valve in a further component, e.g. in a cylindrical receptacle of a housing.  
           [0025]    Guiding elements for the valve body are advantageously disposed on or in the base part next to the valve seat and about the periphery of a circle. The guiding elements which are formed e.g. as projections, permit reliable return of the valve body into its resting position after deflection by an increased fluid pressure. To support this process, bevelled guiding surfaces may be provided on the projections on the side facing the valve body.  
           [0026]    At least three guiding elements are required which subtend, in total, an angle of more than 180 degrees. 4 to 8 guiding elements are preferably uniformly disposed about the valve body. To prevent flow losses, free spaces are advantageously provided between the guiding elements. The guiding elements advantageously extend in the flow direction by at least the amount which corresponds to the maximum stroke of the valve body.  
           [0027]    The invention also concerns an arrangement comprising a seat valve and a component on or in which the seat valve is disposed, wherein the seat valve and the component are permanently welded to each other. This arrangement permits production of a pre-mounted assembly which may be provided as unit for a further mounting process. A seat valve in accordance with the invention, as described above, is preferably used as the seat valve.  
           [0028]    Suitable welding methods are the above-mentioned vibration, rotational, ultrasonic or laser welding methods. Such methods provide a fluid-tight connection between the base part of the seat valve and a further component to prevent leakage and passage of fluid past the seat valve. This also ensures that fluid flow through the seal, fashioned between valve body and valve seat, can be completely interrupted. When the valves are pressed in as in DE 201 08 856 U1, leakages between the pressed parts may occur, in particular, due to high temperature changes.  
           [0029]    Reliable function of the seat valve and prevention of leakage flows is also important when the component connected to the seat valve is formed as, housing, central tube or lid, in particular of an oil filter as described e.g. in DE 195 02 020 C2. The welded joint effectively prevents such leakage.  
           [0030]    In one embodiment of the invention, the component has a receptacle into which the seat valve can be loosely inserted in a pre-mounting position. Such a receptacle permits reliable definition of the relative position between the seat valve and the further component. The at least partial interposing of seat valve and component moreover provides a particularly compact unit.  
           [0031]    The receptacle advantageously has an abutment section for abutment of the collar of the seat valve described above. This abutment section represents the counter piece of the collar disposed on the base part of the seat valve. When the valve is pre-mounted, the collar is initially loosely supported on the abutment section before the collar and the abutment section are welded to each other. The collar may therefore be largely flat and excessive material (e.g. in the form of a thickening) may be provided on the abutment section of the housing for producing a welded joint between the base part and e.g. the housing.  
           [0032]    It is also advantageous when the receptacle has a step which cooperates with the shoulder provided on the cover part. This ensures reliable positioning of the cover part in the housing.  
           [0033]    The abutment section and the step preferably have surfaces which are perpendicular to the incoming flow direction of the seat valve, the surfaces being disposed parallel to the contact surfaces of the base part and the cover part of the seat valve. This embodiment permits transfer of forces, introduced into the shoulder of the cover part, via the contact surface of the cover part onto the contact surface of the base part and on to the abutment section of a housing. The mutually parallel surfaces which are all disposed perpendicular to the incoming flow direction of the seat valve permit particularly effective passage of force flow.  
           [0034]    In a particularly advantageous fashion, the separation between the surfaces of the abutment section perpendicular to the incoming flow direction of the seat valve and the step is at least slightly less than the separation between the surface of the collar of the base part facing the incoming flow direction of the seat valve and the shoulder of the cover part. This ensures relief of the locking connection disposed between the step of the cover part and the collar of the base part. The fact that the separation between the abutment section and the step in the receptacle of the component receiving the seat valve is slightly smaller, the entire seat valve and, in particular, the region between collar and shoulder in which the locking connection is disposed, is pretensioned thereby relieving the locking connection which is loaded when fluid flow is present.  
           [0035]    It may also be advantageous when the separation between the surfaces of the abutment section which are perpendicular to the incoming flow direction of the seat valve and the step is at least slightly larger than the separation between the surface of the collar of the base part facing the incoming flow direction of the seat valve and the step of the cover part. As long as the locking connection between the shoulder of the cover part and the collar of the base part is intact, the base part and cover part are held together via this locking connection. If the locking connection should fail, the base part is still fixed on the abutment section of the installation position while the cover part may be supported with its shoulder on the step provided at the installation position, thereby maintaining full function of the valve even when the locking connection fails.  
           [0036]    Further advantageous embodiments and details of the invention can be extracted from the following description which describes and explains the invention in more detail with reference to the embodiment shown in the drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0037]    [0037]FIG. 1 shows a cross-sectional side view of an inventive seat valve;  
         [0038]    [0038]FIG. 2 shows a cross-sectional side view of a seat valve installed in an oil filter arrangement; and  
         [0039]    [0039]FIG. 3 shows a cross-sectional side view of a further inventive seat valve. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0040]    In accordance with FIG. 1, a seat valve is designated in its totality with reference numeral  2 . The seat valve  2  consists substantially of a base part  4  shown at the top of FIG. 1 and a cover part  6  shown at the bottom of FIG. 1. The base part  4  and the cover part  6  are connected to each other via a locking connection  7 , which is described in more detail below.  
         [0041]    A valve body  8  is displaceably disposed in the cover part  6 , and cooperates with a valve seat  10  formed on the base part  4 . The valve body  8  is held in the position shown in FIG. 1 by means of a spring element  12  supported on the cover part  6 . When fluid enters in accordance with the incoming flow direction  14  and the holding force generated by the spring element  12  is overcome, the valve body  8  can be moved downwardly (as viewed in the drawing) away from the valve seat  10  and incoming fluid can escape through outlet openings  16  provided in the cover part  6 .  
         [0042]    The base part  4  of the seat valve  2  has a collar  18  on its front side facing the flow direction  14 , which has an annular shape and has a collar surface  20  on the side facing away from the incoming flow direction  14  which also has a peripheral thickening  22 . The collar surface  20  serves as abutment surface for a component described with reference to FIG. 2, wherein the thickening  22  serves as material storage for producing a welded joint.  
         [0043]    The locking connection  7  formed between the base part  4  and the cover part  6  is described in more detail below. The cover part  6  has locking arms  24  on its side facing the base part  4  with radially inner locking sections  26 . The locking sections  26  have bevelled front surfaces  28  on their side facing the incoming flow direction  14  which are joined by side surfaces  30  which extend parallel to the flow direction  14 . The side surfaces  30  are joined by front surfaces  32  which are oriented perpendicular to the flow direction  14 .  
         [0044]    The locking arms  24  have a contact surface  34  on the front side facing the base part  4  which are oriented substantially perpendicular to the incoming flow direction  14 . The contact surfaces  34  are plane-parallel to the contact surfaces  36  provided on the base part  4 .  
         [0045]    The contact surface  36  of the base part  4  is joined by a first inclined flank surface  38  and a second flank surface  40  which is oriented parallel to the incoming flow direction  14 . The flank surface  40  is again joined by a bridge surface  42  which is oriented perpendicular to the incoming flow direction and which is formed by a bridge  44  which is disposed at the same height as the valve seat  10 , viewed in the incoming flow direction. The contact surface  36 , the flank surfaces  38  and  40  and the bridge surface  42  form a receiving space for the locking sections  26  on the locking arms  24  of the cover part  6 .  
         [0046]    The locking arm can be gradually pushed radially outwardly by the bevelled front surface  28  when the cover part  6  is mounted to the base part  4 , until the front surface  32  of the locking section  26  which is oriented perpendicular to the incoming flow direction  26  comes into engagement behind the bridge surface  42  of the bridge  44 . This construction ensures simple mounting of the cover part  6  to the base part  4 . Moreover, the perpendicular orientation of the front surface  32  and the bridge surface  42  ensures that the cover part  6  cannot be removed from the base part  4 .  
         [0047]    The locking arms  24  of the cover part  6  form a cover part section  46  on the incoming flow side which is delimited by a radially inwardly offset shoulder  48 . The shoulder  48  is joined, viewed in the flow direction, by the cover part section  50  on the flow discharge side which has smaller outer dimensions than the cover part section  46  on the incoming flow side. The shoulder  48  serves for abutment on a step provided in a further component, as is explained in more detail with reference to FIG. 2.  
         [0048]    The valve body  8  consists essentially of one valve disk  52  whose edge has a conical section facing the flow direction  14  which cooperates with a correspondingly formed conical section of the valve seat  10  in the base part  4 . The valve body  8  has a central piston-like extension  54  on its side facing away from the incoming flow direction  14 . The extension  54  engages in a cylindrical guidance  56  provided in the cover part  6  which has an opening  58  on the front side at the flow discharge side. This opening prevents collection of dirt particles in the guidance  56  of the extension  54 .  
         [0049]    Guiding elements  59  for the valve disk  52  are formed as projections disposed adjacent to the valve disk  52  along a circular periphery. FIG. 1 shows a section of two elements of the total of six guiding elements  59 . They have guiding bevels  59   a  on the side facing the valve disk  52 .  
         [0050]    The seat valve  2  is shown in a possible installation position in FIG. 2. The seat valve  2  is mounted in a component in the form of a central tube  60  of an oil filter arrangement, wherein the central tube  60  is mounted via locking arms  62  in locking receptacles  64  which are provided on a lid  66 . The lid  66 , central tube  60 , and seat valve  2  can be inserted in and mounted to an oil filter housing (not shown) via a screw thread  68  provided in the lid  66 . The seat valve  2  separates a high-pressure space  70  on the lid side from a low pressure space  72  located inside the central tube  60  in the situation shown in FIG. 2. The seat valve  2  is fixed via the collar  18  of the base part  4  to an abutment section  74  which is provided on the front side of the central tube  60  facing the high-pressure space  70 .  
         [0051]    The seat valve  2  is welded to the abutment section  74  of the central tube  60  via the collar  18  and the thickening  22 , shown in more detail in FIG. 1. Since the seat valve  2  and the central tube  60  are substantially rotationally symmetrical, the seat valve  2  and the central tube  60  can be connected to each other through a rotational welding method.  
         [0052]    The central tube  60  has a step  76 , viewed from the abutment section  74  in the flow direction  14 , on which the shoulder  48  of the cover part  6  abuts. The step  76  exactly defines the position of the cover part  6  of the seat valve  2  within the central tube  60 . The separation  78  between the abutment section  74  and the step  76  is slightly smaller than the separation  80  between the collar surface  20  of the collar  18  and the shoulder  48  of the valve cover  6 . The arrangement of base part  4  and cover part  6  is thereby pretensioned which relieves the locking connection  7  between base part  4  and cover part  6 .  
         [0053]    When fluid flows towards the seat valve  2  in the incoming flow direction  14 , the valve body  8  can be displaced in the flow direction such that the extension  54  is further immersed into the cylindrical guidance  56  in the cover part  6 . The valve body is thereby supported by a spring element  12  (shown in FIG. 1). The spring element  12  is, in turn, supported on the cover part  6  which can relieve the forces produced by the flow through the shoulder  48  into the central tube  60 . The forces are no longer deflected into the central tube  60  via the cover part  6 , the locking connection  7 , the base part  4  and the collar  18 . Consequently, the locking connection  7  is relieved and the high functional safety of the inventive seat valve  2  is improved.  
         [0054]    The seat valve  2 ′ shown in FIG. 3 comprises a base part  4 ′ and a cover part  6 ′ The seat valve  2 ′ differs from the seat valve  2  of FIG. 1 in that the separation between a contact surface  34 ′ and a shoulder  48 ′ is relatively small: in the embodiment, the separation corresponds approximately to the thickness of the wall sections of the cover part  6 ′ extending in the flow direction. This is advantageous in that a component may have a relatively shallow bore for receiving the seat valve  2 ′ s to form a step for abutment on the shoulder  48 ′ (compare the separation  78  between the abutment section  74  and the step  76  of FIG. 2).