Abstract:
A pressure valve, particularly for a reciprocating piston pump for conveying pressure fluid in slip-controlled hydraulic brake systems, wherein the pressure valve has a valve seat body and a valve cover body with a pre-tensioning element and a valve element installed in the space formed between the valve seat body and the cover body, which is particularly economical to manufacture, easy to install and particularly safe because of the valve seat body and the valve cover body being manufactured by non-cutting process.

Description:
TECHNICAL FIELD 
     The present invention generally relates to valves, and more particularly relates to a pressure valve for a reciprocating pump for conveying pressure fluid in slip-controlled hydraulic brake systems. 
     BACKGROUND OF THE INVENTION 
     A pressure valve of this general kind is disclosed in DE 44 07 978 A1. The pressure valve described in this paper is part of a hydraulic pump which is used for conveying pressure fluid in hydraulic brake systems. In addition to the pressure valve, the hydraulic pump also has a suction valve and a pump piston. The function of the hydraulic pump consists of conveying by piston action the brake fluid into the brake circuit when required. Pressure and suction valve are controlled by pressure. The stroke movement of the pump piston is generally generated by a cam on the drive shaft of an electric motor. 
     The pressure valve as defined in this state of the art, is threaded into the pump housing by a thrust piece with screw connection (cf. FIG. 2 as well as column 4, lines 17 to 21). The connection of the valve seating and thrust piece or valve cover is by way of a pliable seal (e.g. by caulking). This known form of design means that the pressure valve has to be manufactured by cutting process such as turning or milling. This means not only high manufacturing costs and tolerance requirements but also the disadvantage with components manufactured by metal-cutting, especially valves manufactured by metal-cutting, that shavings can get into the brake circuit which can restrict the function of the brake system and therefore the vehicle&#39;s safety. Another disadvantage of the known pressure valve is that the screw connection of the pressure valve to the pump housing can be altered after installation meaning that manipulation is possible to the brake system by unauthorized persons. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to overcome the disadvantages of the state of the art and in particular to create a valve or pressure valve which is economical to manufacture, easy to install and particularly safe with regard to function. 
     This object is achieved by the invention of a pressure valve of the type named initially wherein the valve seat and/or the valve cover body are manufactured by non-cutting means. Preferred means of manufacture of the valve seat body and/or the valve cover body of the pressure valve are forming, reforming, punching, stamping and similar. 
     In a preferred embodiment of the present invention, the pressure valve is caulked into the pump housing. This type of fastening of the pressure valve provides a connection of the pressure valve with the housing which is safe against manipulation and pressure-resistant. In connection with a pressure valve with individual parts that have been manufactured by non-cutting means, this type of fastening offers a distinct advantage because caulking the pressure valve is also possible even if the valve cover, for example, has no thread for fastening into the pump housing or the valve block. 
     A preferred embodiment of the present invention shows the pressure valve as an autonomous installation subassembly suitable for handling. This has the advantage that it simplifies the installation of the pressure valve in a hydraulic pump and allows the pressure valve to be tested externally and separately prior to installation. 
     According to a possible embodiment, an adhesive joint is provided for the connection of the valve seat body and the valve cover body. The adhesive used is preferably a micro-encapsulated adhesive which does not have to be resistant to brake fluid because the connection of the valve seat body and the valve cover body is only necessary as an installation aid and during a test phase prior to installation. 
     According to another embodiment the pressure valve has a connecting device for connecting the valve seat body to the valve cover body. This connecting device is preferably in the form of a spring cup in which the spring is guided, wherein the spring cup preferably has at least one opening for the connection of the valve interior with a pressure fluid consumer. 
     A further preferred embodiment of the present invention has a self-locking connection between the valve seat body and the valve cover body. This is preferably realized by contacting angled surfaces. 
     The valve seat body and/or the valve cover body should preferably have at least one opening for the connection of the valve interior with a pressure fluid consumer. A particular advantage can be achieved by the valve seat body and/or the valve cover body having a further opening for controlling the resulting ball force. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a longitudinal section through a first embodiment of a pressure valve according to the present invention. 
     FIG. 2 a sectional view of a second embodiment of a pressure valve according to the present invention. 
     FIG. 3 a longitudinal view of a third embodiment of a pressure valve according to the present invention. 
     FIG. 4 a sectional view of a fourth embodiment of a pressure valve according to the present invention. 
     FIG. 5 a longitudinal view of a fifth embodiment of a pressure valve according to the present invention. 
     FIG. 6 a further sectional view of a sixth embodiment of a pressure valve according to the present invention. 
     FIG. 7 a longitudinal view of a seventh embodiment of a pressure valve according to the present invention. 
     FIG. 8 a sectional view of the seventh embodiment shown in FIG. 7 along the dash-dotted line VIII—VIII. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 contains a sectional view of a first embodiment of a pressure valve  1  according to the present invention, in particular of a hydraulic pump. The hydraulic pump can be used in particular for ABS Anti-Lock Braking System), ASR (Anti Slip Regulator), ASMS (Automatic Stability Management System) or ESP (Electronic Stability Program) in a controlled brake system. A coaxial suction valve  2  is connected upstream of the pressure valve  1 . The pressure valve  1  and the suction valve  2  are located in the valve block or pump housing  3 . It can be seen from FIG. 1 that the pressure valve  1  which is preferably designed as an autonomous assembly unit suitable for handling is caulked into pump housing  3 . Suction valve  2  is located in a guiding hole  4  of pump housing  3 . Guiding hole  4  is sealed pressure tight outwardly by pressure valve  1  which cannot be removed without destruction. A pump piston  5  is moved back and forth in guiding hole  4  by a cam (not shown) on a drive shaft (also not shown). Suction valve  2  is fastened onto piston  5  by a retaining cage  6 . A reset spring  7  is located in pressure chamber  8  in the space between the bent end section of the retaining cage  6  and the pressure valve  3 . Suction valve  2  abuts on a suction channel  9  formed in pump piston  5 . 
     Pressure valve  1  of a predominantly rotationally symmetrical design has a valve seat body  10 , a valve cover body  11  and a spring  12  in between. The valve seat body  10  and the valve cover body  11  are preferably punched or stamped parts. The spring  12  in this embodiment consists of a predominantly planar spiral spring which presses a ball or a valve element  13  against a central hole  14  in valve seat body  10 . On its outside spring  12  is held between the valve cover body  11  and the valve seat body  10  in a ring-shaped recess  15  in the valve cover body  11 . The spring  12  is virtually flat in an unloaded state and can therefore be mounted unaligned. 
     Furthermore, this design of the spring  12  makes the pressure valve particularly shallow. The valve seat is formed by a conical recess  16  adjoining and concentric to the central hole  14 . The diameter of the hole  14  corresponds approximately to the radius of the ball  13 . The outer diameter of the recess and the valve seat  16  is a little larger than the diameter of the ball  13 . A shallow recess  17  is formed in the valve seat body  10  around the recess  16 . Engraved grooves or openings  18  extend outwards radially from the shallow recess  17  into the valve seat  10  in order to conduct fluid out from the space  19  formed between the valve cover body  11  and valve seat body  10 . The grooves  18  are connected with a ring chamber  20  formed between the inner wall of the pump housing  3 , the outer circumference of the valve seat body  10  and section of the valve cover body extending radially over the valve seat body  10 . Said ring chamber  20  itself is connected to a channel  21  which leads to a pressure fluid consumer such as the wheel brakes of a hydraulically controlled brake system. The space  19  is formed by a dome-shaped projection  22  on the side of the valve cover body  11  facing the valve seat body  10  which is achieved by the concave form, e.g. by embossing, of the valve cover body  11 . 
     As one can see from the illustration in FIG. 1, the thickness of the valve seat body  10  and the thickness of the valve cover body  11  is mainly constant which is a particular advantage for non-cutting production. The valve seat and the valve cover body  10  and  11  can therefore be manufactured easily from a metal panel or similar. 
     When in operation, during a pressure stroke phase, a stroke movement of the piston  5  causes a pressure increase in pressure chamber  8  which opens the pressure valve  1  against the pretension of spring  12  and the pressure or brake fluid is transported through the grooves  18 , the ring channel  20  and the channel  21  to a pressure fluid consumer, e.g. the wheel brakes. 
     The second embodiment of an pressure valve according to the present invention shown in FIG. 2 has a thin sheet metal plate  12 ′ instead of the spring  12  and can also be described as a plate spring. A tongue stamped out of the plate spring  12 ′ presses the ball  13  against the valve seat  16 . The use of the plate spring  12 ′ provides a particularly flat design form just as the use of a spring  12  which is planar when in an unloaded state. 
     In the case of the third pressure valve  1  according to the present invention as shown in FIG. 3, a coil spring  12 ″ has been used instead of the spiral spring  12  (cf. FIG.  1 ). In this case, the coil spring  12 ″ is guided in the valve seat body  10 . Therefore, instead of the conical recess  16  (cf. FIGS. 1 and 2) the valve seat body  10  has a recess  23  in the bottom section of which the ball is located. The diameter of hole  23  is a little larger than the diameter of ball  13  and the coil spring  12 ″. The valve seat body  11  is thicker in an inner radial section with the recess  23  than at its edge so that a sufficient section of the spring  12 ″ and the ball  13  fit in it for guiding of the spring  12 ″. An upper section of the hole  23  facing the valve cover body  11  serves to guide an end section of the coil spring  12 ″ above the ball  13 . The end section of the coil pressure spring opposite this end section is mounted in a step-like section  24  in the valve cover body  11 . The recess  23  and the section  24  have approximately the same diameter, face each other and are arranged in a coaxial position to each other. In the embodiment shown in FIG. 3, the grooves or openings  18  are located in an edge section of the valve cover body  11  instead of in the valve seat body  10 . 
     FIG. 4 shows a fourth embodiment of the present invention. Unlike the design example shown in FIG. 3, in this case the coil spring  12 ″ is mounted in the valve cover body  11 . Instead of the recess  23  in the valve seat body  10 , the projection  22  in the valve cover body  11  has an engraved, mainly pot-shaped section  24  in which is fed an end section of the spring  12 ″ opposite the ball  13 . In the case of the embodiment shown in FIG. 4, the grooves  18  are formed in an edge section of the valve cover body  11  instead of the valve seat body  10 . 
     The fifth embodiment of the pressure valve  1  according to the present invention shown in FIG. 5 is on the whole similar to the embodiment shown in FIG. 1 with the main difference, however, that the spring  12  is fastened onto the valve seat body  10  for example by caulking. This is shown schematically in FIG.  5 . As with the embodiments shown in FIGS. 3 and 4, the grooves  18  are formed in the valve seat body  11 . 
     Because of the effect of the piston reset spring  7 , pressure valve  1  is preferably designed as a separate mounting unit suitable for handling. In the case of the pressure valve  1  according to the present invention as shown in the embodiments shown in FIGS. 1 to  5 , the valve seat body  10  and the valve cover body  11  are fastened to the facing ring-shaped outer sections, for example, by welding connection or adhesive or glue connection. In the latter case, a micro-encapsulated adhesive can be used which only becomes active when the valve seat body  10  and the valve cover body  11  are pressed together. The adhesive used does not have to be resistant to brake fluid because the pressure valve  1  only has to form a unit as installation aid. 
     FIG. 6 shows a sixth embodiment of the present invention. An additional holding element is used for connecting the valve seat body  10  with the valve cover body  11 : a spring cup in the form of a connecting device. In this embodiment the connection of the valve seat body  10  with the valve cover body  11  is therefore not temporary—as is the case with the above-described adhesive connection—but is permanent instead. The spring cup  25  is fastened into the valve cover body  11  by press fitting or similar. Fastening of the spring cup  25  to the valve seat body is achieved by the end section  26  of the spring cup  25  being beaded around the valve seat body  10 . A cross-section of the spring cup  25  shows that it is mainly U-shaped in the base section  27  where the coil spring  12 ″ is guided. A horizontal middle section  28  running parallel to the valve seat body  10  adjoins the base section  27 . Instead of the grooves  18  which are formed in the valve seat body  10  or the valve cover body  11  in the embodiments shown in FIGS. 1 to  5 , in this embodiment the spring cup  25  has openings or recesses  29  stamped in its middle section  28  which act as connection between the chamber  19  and the channel  21 . 
     A seventh embodiment of the present invention is described in connection with FIGS. 7 and 8. FIG. 7 shows a cross-section of a pressure valve  1  according to the present invention and FIG. 8 shows a cross-section view along the dash-dotted line VIII—VIII in FIG.  7 . The pressure valve  1  shows a valve seat body  10  which is preferably designed as a valve plate made of steel and a valve cover body  11  which is preferably a stamped part made of aluminum. On its side facing the pressure chamber  8 , the valve seat body  10  has a sealing edge  30  around its circumference. Furthermore, the valve seat body  10  also has a valve seat  31 . A particularly sharp edged design of the valve seat  31  has the effect that the brake fluid can flow out sideways immediately after passing the narrowest cross-section when pressure valve  1  is opened. This means that it is not necessary for the (brake) fluid to flow around the ball  13 . The outer edge of the valve seat body  10  slopes at an angle α. The valve cover body  11  has a radial inner section  32  with U-shaped cross-section and a radial outer section  33  which also has a U-shaped cross-section. The inner diameter of the inner section  32  which serves in particular to provide stability for the ball  13  and guiding of the coil spring  12 ″ corresponds mainly with the diameter of ball  13 . This means that the guiding of ball  13  is tight and precise, i.e. with very little play, which avoids any “dancing” by ball  13  as could be caused by burbling. The inner diameter of the outer section  33  corresponds mainly with the outer diameter of the valve seat body  10 . The outer section  33  clasps the valve seat body  10  and is also angled on its inner side at an angle α. The angle α in this case is smaller than the critical angle for self-locking so that both components  10  and  11  hold together by themselves and the pressure valve  1  can be handled and tested as a separate sub-assembly. It should also be pointed out that both the valve seat body  10  and the valve cover body  11  can be manufactured in one clamping. 
     A groove  18  formed in the outer section  33  of the valve cover body  11 , which can also be described as the outflow opening, serves as connection between the space  19  with the ring chamber  20  and the channel  21 . Furthermore, the outer section  33  of the valve cover body  11  has the advantage of an embossed additional opening  36 . The illustration in FIG. 8 shows that the groove  18  and the additional opening  36  on the inside of the outer section  33  are set at angle β to each other. When pressure valve  1  is opened, the brake fluid flows out of the space  19 , around the ball  13  and through the additional opening  36  as indicated by the arrows in FIG.  7 . In addition to this, an equally large volume of brake fluid is forced out of the space  19  through the ring gap  37  around ball  13  for tolerance reasons. The resulting force on the ball  13  can therefore be influenced by setting the angle β, thus providing a preferred abutting surface for the ball  13 . 
     The design example as shown in FIGS. 7 and 8 is characterized by a particular construction-related noise reduction. The pressure valve is pre-mounted and forms a unit during operation as well because of the self-locking design. The installation of the pressure valve in the pump housing  3  is carried out in two stages. In the first stage, the pressure valve  1  is pressed onto the valve seat body  10  in order to ensure a tight seal. Following this, a probe is mounted onto the outside of the pressure valve  1  which is used for testing the pressure valve  1  during a pump trial run. A sealing section of the probe outside the pump housing  3  provides the required seal for operating the pressure valve  1 . Finally, upon successful completion of the test, the pressure valve  1  is caulked into place while retaining the original test position and is therefore pressure-tight and cannot be removed from the valve block.