Abstract:
A hydraulic pressure regulating valve for regulating a pressure in an automatic transmission of a motor vehicle, comprising a magnetic part which includes an electrically controllable coil, a coil core and a movable armature, a valve flange which is anchored on the magnetic part and has pressure medium guiding passages, a piston controlling a pressure in a passage connected to a consumer, the piston being loaded with the armature and controlling pressure medium connections between the passages, a diaphragm element which seals the valve flange relative to the magnetic part, a return passage, the diaphragm element having at least one pressure chamber which is hydraulically connected with the return passage, and a throttling device formed so that the pressure chamber is connected with the return passage through the throttling device.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to hydraulic pressure regulating valves.  
           [0002]    Pressure regulating valves are used for example in hydraulic controls of automatic transmissions of motor vehicles. Their objective is to control transmission components such as for example couplings and to regulate their pressures.  
           [0003]    A hydraulic pressure regulating valve is disclosed for example in the German patent document DE 43 24 748 A1. This pressure regulating valve is composed of a magnetic part and a valve flange which is anchored on it. The magnetic part includes an electrically controllable coil, a coil core and a movably guided armature which is held by a spring in the base position. The armature actuates a piston which is guided movably in the valve flange and which for regulation of the pressure releases or closes pressure medium connections between passages. The valve flange is sealed from the magnetic part by a diaphragm element. The latter is ring-shaped and fixed with its outer periphery on the valve body and with its inner periphery on the piston. The diaphragm element thereby follows the movement of the piston. In order to avoid a pressure buildup in an inner chamber of the diaphragm element, the ubber chamber is connected with the return of the pressure regulating valve.  
           [0004]    The armature movement of the pressure regulating valve is performed undampened. Thereby the pressure regulating valve is relatively sensitive to mechanical vibrations of the magnetic circuit or pressure fluctuations of the pressure regulating circuit. For many applications such undampened regulating condition is undesirable. In known pressure regulating valves, a dampening of the stroke movement of the piston can be performed with the use of separate dampening devices, for example a so-called spring accumulator. Such dampening devices have the disadvantages of their large mounting space, unfavorable dynamics, and relatively high costs.  
           [0005]    It is also known to dampen the stroke movement of the piston in a pressure regulating valve via so-called gap dampening in the magnetic part. For this purpose the magnetic part, in contrast to the solution disclosed in the German reference DE 43 24 748 A1, is filled with pressure medium. The gap between the armature and the wall of the armature chamber and/or throttling openings in the armature form throttling elements for dampening of the medium stream which is displaced by the armature during its movement and thereby also the piston movement. A substantial disadvantage of the dampening of this type is on the one hand its dependence on the filling degree of the armature chamber with pressure medium, and on the other hand its temperature dependence because of the laminar stream which is formed in the relatively long throttle gaps. A further problem resides in entrainment of dust particles into the armature chamber which is filled with a pressure medium. These impurities negatively influence the magnetic characteristics of the pressure regulating valve, can cause wear of the components of the magnet parts or can deposit in the dampening gaps.  
         SUMMARY OF THE INVENTION  
         [0006]    Accordingly, it is an object of the present invention to provide a hydraulic pressure regulating valve, which avoids the disadvantages of the prior art.  
           [0007]    In keeping with these objects and with others which will become apparent herein after, one feature of the present invention resides, briefly stated, in a pressure regulating valve has a magnetic part which includes an electrically controllable coil, a coil core and a movable armature; a valve flange which is anchored on said magnetic part and has pressure medium guiding passages; a piston controlling a pressure in a passage connected to a consumer, said piston being loaded with said armature and controlling pressure medium connections between said passages; a diaphragm element which seals said valve flange relative to said magnetic part; means forming a return passage, said diaphragm element having at least one pressure chamber which is hydraulically connected with said return passage; and a throttling device formed so that said pressure chamber is connected with said return passage through said throttling device.  
           [0008]    When the pressure regulating valve is designed in accordance with the present invention, a dampening device is integrated in the pressure regulating valve and does not change significantly the mounting volume of the valve and also does not require any filling of the magnetic part with pressure medium. The risk of emptying of the armature chamber, for example during transportation of the pressure regulating valve to consumers, is thereby prevented, and also a possible dirtying of the armature chamber during the operational time. In addition the required structural features of the components are manufactured in cost-favorable manner.  
           [0009]    In accordance with the present invention it is especially advantageous when the guidance of a piston in the valve flange for forming of the damping device is utilized. This throttle device can be easily adjusted to corresponding requirements of the applications for the pressure regulating valve, by varying the gap dimension or the piston guide with recesses of different geometries and/or dimensions.  
           [0010]    In an advantageous further embodiment of the invention, the magnetic part is formed as a proportional magnet, in which the armature is inserted at least partially into the interior of the magnetic core. Pressure regulating proportional magnetic valves have a very exact and accurate control of nominal pressure values, without requiring an expensive pressure regulating circuit. Thereby such pressure regulating valves are especially suitable for applications in of mass production, such as for example in the automobile industry.  
           [0011]    The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIGS. 1 and 2 show two embodiments of a pressure regulating valve in accordance with the present invention in a longitudinal cross-section, with a pressure regulating valve in FIG. 1 formed as a 3/2 pressure regulating valve with a falling pressure/flow characteristic line in a slider construction, while FIG. 2 shows a pressure regulating valve in a seat construction.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    A pressure regulating valve in accordance with the present invention is shown in FIG. 1 and identified with reference numeral  10 . It has a magnetic part  12  and a valve flange  14  which is connected to the latter. The magnetic part  12  includes a hollow-cylindrical coil  16 , a sleeve-shaped coil core arranged in the interior of the coil  16 , and a movably guided armature  20 . The latter is arranged at the end side of the coil  16  which faces the valve flange  14  and overlaps it.  
         [0014]    For its axial guidance, the armature  20  has a pin  24  which is mounted in a central opening  22  extending through the armature. It extends into a sliding bushing  26  which is anchored in the coil core  18 . The sliding bushing  26  is inserted in a blind hole-shaped recess of a plug  28  which is screwed in the sleeve-shaped coil core  18  and closes the same from outside. The plug  28  is changeable in its relative position relative to the coil core  18 . A spring  30  which is centered by the pin  22  is supported on it. With its second end it abuts against the armature  20 . The pre-tensioning of the spring  30  is adjustable via the relative position of the plug  28  relative to the coil core  18  during the mounting of the pressure regulating valve. The function of the spring  30  is to provide a restoring force which brings the armature  20  in powerless condition of the coil  60  to the illustrated base position of the pressure regulating valve  10 .  
         [0015]    The magnetic part  12  is injection-molded with a synthetic plastic casing  34  with embedding of an element  32  which conducts the magnetic flux. Contact tongues  36  extend outwardly from the synthetic plastic casing  34 . Electrical contacting of the coil  16  with a not shown control electronic system is provided through the contact tongues  36 .  
         [0016]    The armature  20  of the magnetic circuit is disc-shaped and has a central portion  38  with a reduced outer diameter. It extends in direction of the coil  16  and also in direction of the valve flange  13 . An elastic guiding disc  40  is anchored at the end of the central portion  38  which faces the valve flange. It is fixed with its outer periphery with a magnetic flux conducting element  32  and the valve flange  14 . The guiding disc  40  together with the pin  22  guarantees the exact guidance of the armature  20 .  
         [0017]    The armature  20  moreover is provided with throughgoing openings  42  in the region between its outer diameter and the diameter of the central portion  38 . One of such openings is shown in FIG. 1. The throughgoing openings  42  are distributed uniformly around the circumference of the armature and connect the part of the armature chamber  44  located about the armature  20  with its part located below. Identical conditions which are thereby provided in the both parts of the armature chamber  44  guarantee the undampened movement of the armature  20 .  
         [0018]    It should be mentioned that the above shown design of the magnetic part  12  is purely exemplary and is not limiting for the scope of the present invention. The design of the magnetic part  12  as such does not constitute the inventive features. Any other magnetic circuit design or armature support which can not be provided for the realization of the invention can be utilized. For the operation of the invention an undamped movement of the armature  20  in the magnetic part  12  must be however guaranteed.  
         [0019]    The armature  20  cooperates with the piston  46  which is guided in the valve flange  14  in a force-transmitting manner. For this purpose the valve flange  14  is formed for example as a pressure cast part which is flanged in the magnetic part  12 . The valve flange  14  is provided with a guiding opening  44  which extends in direction of its longitudinal axis and receives the piston  46 . The guiding opening  44  opens at the end of the valve flange  14  which faces the magnet, into an opening  56  which opens toward the magnetic part  12 . The recess  50  is expanded in its diameter relative to the guiding opening  48  and forms a mounting space for a diaphragm element  52 .  
         [0020]    The diaphragm element  52  separates the recess  50  in two pressure chambers  50   a  and  50   b  which are separated from one another and seals the magnetic part  20  relative to the valve part  14 . For this purpose the diaphragm element  52  is ring-shaped and is mounted on its diameter in a slot  54  on the periphery of the piston  46 . The outer diameter of the diaphragm element  52  is received in a groove  56  which is formed on the valve flange  14 . It is fixed there by a holding ring  56  which is clamped in the recess  50 . The diaphragm element  52  has such dimensions that it can follow an axial movement of the piston  46  within the control of the coil  16 .  
         [0021]    The hydraulic connections  61 ,  62 ,  64 , of the pressure regulating valve  4  are formed on the valve flange  14 . A not shown hydraulic consumer is connected with the connection  61 , which in the preferable embodiment of the pressure regulating valve  10 , is a following valve over a coupling. The connection  62  is connected with a not shown pressure generator and acts as a supply of the pressure regulating valve  10 . The connection  64  is connected with a not shown pressure medium supply container and acts as a return. Moreover, a contact connection  64  schematically shown in FIG. 1 is provided between the connection  61  at the side of the consumer and a connection  60  at the end of the guiding opening  48  which is opposite to the magnetic part  12 . The end surface of the piston  46  is loaded with a working pressure through the connection  60 , to guarantee its abutment against the armature  20 .  
         [0022]    The connection  61  is formed as a ring groove  61   a  on the periphery of the valve flange  14  and opens through a radially extending working passage  61   b  into the guiding opening  48 . Therefore the opening section of a first control cross-section  68  is formed. The connection  62  is arranged between the connection  60  and  61  on the pressure regulating valve  10 . It is also formed as a ring groove  62   a  and is connected through radial supply passages  62   b  with the guiding opening  48 . Therefore this opening part forms the second control cross-section  70  of the pressure regulating valve  10 .  
         [0023]    A return-side connection  64  is provided in direction of the magnetic part  12  above the connection  61  of the pressure regulating valve  10 . It opens through a return passage  64   b  into the guiding opening  48 . For the operation of the above described pressure regulating valve  10  it is important that the connection  64  is located deeper than the pressure medium level in the connected supply container since only in this way the return passage  64   b  is reliably filled with pressure medium under low pressure.  
         [0024]    The passages  61   b ,  62   b , and  64   b  of the pressure regulating valve  10  through which the pressure medium flows are separated by a wall  72  from the pressure chamber  50   a . However, a connecting opening  74  is provided in the valve  72  and couples the pressure chamber  50   a  hydraulically with the return passage  64   b . Thereby the pressure chamber  50   a  is always filled with pressure medium. A throttling device  76  is anchored in accordance with the present invention in the connecting opening  74 . In the shown example it is integrated in a separate hat orifice. The hat orifice is pressed with its circumferential edge up to the abutment in the connecting opening  74 . It has at least one not shown orifice opening at its part which covers the cross-section of the connecting opening  74  with dimensioning of the cross-section of the orifice opening by the material thickness of the heat orifice, the latter can be formed in a simple way as an ideal orifice in accordance with a flow technique. The dampening characteristic of ideal orifices is preferably, in the temperature region under consideration, substantially independent from temperature changes.  
         [0025]    A narrowing  78  is provided in the substantially cylindrical piston  46  for controlling the pressure of the connection  61  of the pressure regulating valve  10  which is connected to the consumer. At the beginning and at the end of the narrowing  78 , two control edges  80 ,  82  are formed on the piston  46 . They cooperate in alternating action with both control cross-sections  68  and  70  of the valve flange  14 . In the shown base position of the pressure regulating valve  10  the second control valve  82  which is located facing away from the magnetic part  12  releases a pressure medium connection between the connection  61  associated with a consumer and the connection  62  of the valve flange  14  associated with a supply. Simultaneously the first control edge  80  of the piston  46  closes the pressure medium connection between the consumer-side connection  61  and the return-side connection  64  of the pressure regulating valve. The consumer is thereby supplied from the pressure generator with pressure medium until the required working pressure is built up and the control edge  82  no longer closes.  
         [0026]    With the electrical control of the coil  16 , the armature  20  is moved due to the produced magnetic force against the restoring force of the spring  30  in direction of the coil  16 . The piston  46  follows because of the loading of its end surface which faces away from the magnetic part  12  with the working pressure of this stroke movement. The free flow cross-section between the control cross-section  68  and the control edge  80  opens, so that the pressure at the consumer-side connection  61  of the pressure regulating valve  12  reduces, until finally the piston  46  completely interrupts the pressure medium connection.  
         [0027]    Due to the anchoring at the piston  46 , the diaphragm element  52  follows the stroke movement of the piston. The volumes of the pressure chambers  50   a  and  50   b  which are separated from one another by the diaphragm element  52  change. With corresponding movement direction of the piston  46  the pressure medium is displaced by the diaphragm element  52  through the connecting opening  74  with the inserted throttling device  66  into the return  64 . The diaphragm element  52  performs in addition to its sealing function also a pumping function. The throttling action produced by the throttling device  76  in the connection passage  34  maintains, depending on the speed, the stroke movement of the piston  46  and acts in a stabilizing way on the regulating properties of the pressure regulating valve  10 . Short-term pressure fluctuations in the pressure regulating circuit, for example mechanically caused vibrations in the magnetic circuit  12  which are transmitted through the armature  20  to the piston  46  remain due to the dampening properties without influencing the pressure level at the consumer.  
         [0028]    An adaptation of the dampening properties to the corresponding applications of the pressure regulating valve  10  is performed by the number of the throttling devices  76 , their geometrical construction and/or dimensions.  
         [0029]    It is to be understood that on the rate of the embodiment of Figure it is also possible to dispense the connecting passage  74  with the inserted throttling device  76 , and to provide between the piston  46  and the wall of its guiding opening  48  in the region between the pressure chamber  58  and the return passage  64   b  a gap as a throttling device  76 . Regardless of this it is advantageous when the connecting passage  74  is formed as the throttle device  76  and therefore a separate hat orifice can be dispensed with. In order to exclude the temperature dependency of the throttling condition, the throttle device  76  can be formed so that in the throttle gap a turbulent stream is introduced. It is achieved with so-called ideal orifices, whose length/diameter ratio is maintained in a predetermined value. Furthermore, it is also proposed in the case of the formation of the throttling device  76  in the connecting passage  74 , to design the gap between the piston  46  and its guiding opening  48  in the region between the pressure chamber  50   a  and the return passage  64   b  so that, a pressure medium leakage from the pressure chamber  50   a  via the gap is excluded. This is achieved through the absolute gap dimension and a correspondingly determined gap length.  
         [0030]    [0030]FIG. 2 shows a second embodiment of an inventive pressure regulating valve  10  with integrated dampening device. Components which are functionally identical to those shown in the preceding figures are identified with the same reference numerals. The pressure regulating valve  10  of FIG. 2, in contrast to the pressure regulating valve of FIG. 1, is formed as a so-called flat seat pressure regulator. It has a valve flange  14  with three hydraulic connections  61 ,  62  and  64 . The working passage-side connection  61  of the pressure regulating valve  10  is now connected with the return-side connection  64  through a valve seat  84 . The third, supply-side connection  62  is arranged between the connection  61  and  64 . It extends perpendicularly to the plane of the drawings, so that in FIG. 2 only its opening cross-section into the working passage  61   b  is recognizable. The connection  64  merges into the return passage  64   b  and opens into the working passage  61   b , while it is located at the opening point of the valve seat  84 . It is designed in form of metallic seat plate  86 , which is injection molded in the valve flange  14 . In the shown base position the valve seat  84  of the pressure regulating valve  10  is closed by a closing member  88 . The closing member  88  in this case is formed of one piece with the armature  20 .  
         [0031]    The valve flange  14  is formed as a synthetic plastic injection molded component, and a sleeve-shaped deep drawn part  90  locally is surrounded by this synthetic plastic injection molded component. The deep drawn part  90  extends outwardly beyond the valve flange  14  and with its outwardly extending end locally engages the magnetic part  12 . Moreover, a throughgoing passage  92  is provided on the deep drawn part  90  in the region of its portion which is surrounded by the valve flange  14 . The throttling device  74  in form of a hat orifice with at least one orifice opening which is not shown in FIG. 2 is inserted in the throughgoing opening  92 . The throttling device  17  is located also in a connecting passage  74  of the valve flange  14 , between the return passage  64   b  and the pressure chamber  50   a  which is limited by the diaphragm element  52 .  
         [0032]    The deep drawn part  90  is injection molded only on the outer side of its inserted end. Its inner side is free from synthetic plastic and forms a guide for the part of the armature  20  which forms the valve piston. With respect to its dampening properties, the second embodiment is identical to the first embodiment, so that the corresponding explanations are dispensed with.  
         [0033]    It should be mentioned that in the second embodiment the coil core  18  and the armature  20  of the magnetic part  12  extend locally into the interior of the hollow-cylindrical coil  16 . This construction of the magnetic part  12  is typical for the pressure regulating valve  10  with proportional regulating functions. In proportional valves the armature  20  between its end positions is bringable to any intermediate positions, whereby a pressure regulation is constantly regulatable by variation of the control voltage of the coil  16 .  
         [0034]    In the pressure regulating valve  10  of FIG. 2 the armature  20  is voluminous. It is a rotation-symmetrical component, with collar  20   a  which covers the coil  16  at the end side. The collar  20  extends in direction of the valve flange  14  into an armature plunger  20   b , at whose end the closing member  88  is formed. The collar  28  in direction of the magnetic part  12  transits into an armature dome  20   c  which is placed inside the coil  16 . A blind-hole-shaped central opening  22  is formed in the armature dome  20   c  and receives the pin  24 . The pin  24  on the one hand centers the spring  30  which returns the pressure regulating valve  10  to its base position and on the other hand provides the pin  24  with armature guidance, since the end extending beyond the armature  20  is inserted in the sliding bushing  26  of the plug  28  that closes the coil core  18 .  
         [0035]    It is to be understood that further changes or additional features are possible without departing from the spirit of the present invention. For example in a pressure regulating valve  10  with pressure medium-free magnetic part  14  a cost favorable damping device  76  can be integrated without increasing the dimensions or the number of the components.  
         [0036]    It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.  
         [0037]    While the invention has been illustrated and described as embodied in hydraulic pressure regulating valve, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.  
         [0038]    Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.