Patent Abstract:
A pressure-control valve includes a housing, a coil carrier, a coil wound on the coil carrier, a first bearing, an armature comprising a valve member. The armature is configured to be axially displaced in the first bearing. A core. A flux guiding device. A connection sleeve comprises a valve seat for the valve member. A first connection bore is configured to be connected with a tank and with the connection sleeve. A second connection bore is configured to be connected with a consumer. An end of the connection sleeve distant from the core comprises a control bore with a control member supported therein. The armature and the control member are configured to be in a force-transmitting operative connection at least in an opening direction of the pressure-control valve

Full Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
       [0001]    This application is a U.S. National Phase application under 35 U.S.C.§371 of International Application No. PCT/EP2011/058410, filed on May 24, 2011 and which claims benefit to German Patent Application No. 10 2010 025 175.5, filed on Jun. 25, 2010. The International Application was published in German on Dec.29, 2011as WO 2011/160910 A1 under PCT Article 21(2). 
     
    
     FIELD 
       [0002]    The present invention relates to a pressure-control valve comprising a housing accommodating a coil wound upon a coil carrier, an armature axially displaceable in a bearing, a core and a flux guiding means, and comprising a first connection bore for connection with a reservoir and a connection sleeve, the connection sleeve comprising a valve seat for a valve member of the armature. 
       BACKGROUND 
       [0003]    Such pressure-control valves are used, in particular, in hydraulic actuators, in controls for automatic transmissions of motor vehicles, or in combination with a pressure or flow-rate controlled motor oil pump. These may be so-called on/off-valves or so-called modulator valves which are advantageous in that the flow rate can be controlled in an infinitely variable manner. An example of an infinitely variable pressure-control valve is described in DE 44 02 523 C2 where the armature of a pressure-control valve, known per se and operating according to the principle of proportionality, cooperates with a valve member which, put simply, is adapted to open and close a connection between a consumer port and a tank. The connection bore to the tank and the connection to the consumer are formed in a connection sleeve. In order to further enhance the damping properties of such a pressure-control valve, a branch includes a buffer damping means. Such a pressure-control valve is very complex and therefore expensive to manufacture and to assemble. The infinitely variable control is also exclusively effected through the electromagnetic drive which also requires high efforts with regard to control technology. 
       SUMMARY 
       [0004]    An aspect of the present invention is to provide a pressure-control valve that is infinitely variable while requiring a low effort with regard to control, and which at the same time exhibits good damping properties. An additional aspect of the present invention is to provide a pressure-control valve which can be manufactured as economically and as simply as possible. 
         [0005]    In an embodiment, the present invention provides a pressure-control valve which includes a housing, a coil carrier, a coil wound on the coil carrier, a first bearing, an armature comprising a valve member. The armature is configured to be axially displaced in the first bearing. A core. A flux guiding device. A connection sleeve comprises a valve seat for the valve member. A first connection bore is configured to be connected with a tank and with the connection sleeve. A second connection bore is configured to be connected with a consumer. An end of the connection sleeve distant from the core comprises a control bore with a control member supported therein. The armature and the control member are configured to be in a force-transmitting operative connection at least in an opening direction of the pressure-control valve. It is thereby possible to control, for example, the delivery rate or the oil pressure of a motor oil pump in a simple manner. For this purpose, for example, the first connection bore should be connected to a tank and the second connection bore should be connected to the consumer to be controlled. The control pressure prevails at the control member, the pressure and the magnetic force together acting against the spring force, both with regard to their direction and the sum of forces. In this manner, a simple oil pressure control of the consumer is provided, with the control member additionally being adapted to be used as an integrated damping means. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present invention is described in greater detail below on the basis of embodiments and of the drawing in which: 
           [0007]      FIG. 1  illustrates a sectional view of an embodiment of a pressure control valve of the present invention, with the integration into an oil circuit being shown schematically for clarification of operation. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    In an embodiment of the present invention, the housing can, for example, be built from a upper part and a lower part, wherein the lower part comprises the connection sleeve and the connection bores and is arranged in the upper part of the housing either positively or non-positively, wherein a bearing bush for the armature is provided in the portion of the lower part facing to the core and a bearing bushing for the control member is provided in the control bore of the connection bore. In this manner, a pressure-control valve that is particularly simple to produce and to assemble is provided. 
         [0009]    By designing the control member as a piston element, it becomes possible to seal the connection to the consumer in a simple manner against the connection to the controlled variable. The fact that the valve member is cone-shaped provides for a tight, linear abutment of the valve member and the valve seat when the valve is in the closed state. A pressure-control valve that is particularly simple to assemble is realized by providing the armature and the control member as an integral structure, wherein the valve member and the control member are connected by a connection body of reduced diameter that is configured as a connection rod. The difference between the diameter of the bore of the valve seat and the diameter of the connection rod determines the flow area in front of the valve seat, with the forces from the control pressure acting on the valve seat and on the control member being in equilibrium in the closed state. 
         [0010]    The interior can be supplied with atmospheric pressure in a simple manner by forming the first connection bore above the valve seat and by forming the second connection bore between the valve member and the control member. When the bearing bush for the armature is offset backward with respect to the first connection bore, an unimpeded flow is obtained between a consumer and the tank. The risk of oil leakage to the environment or the risk of a damage to the electromagnetic drive caused by pressure variations is very low due to the fact that the armature has a transversal groove, if it is a separate armature, or a transversal bore, in case of an integral control member/armature structure, and a longitudinal bore, such that atmospheric pressure prevails in the interior of the pressure-control valve above the armature. 
         [0011]    In an embodiment of the present invention, the lower part can, for example, be bipartite, with the first part supporting the armature and having the first connection bore formed therein, and the second part being formed with the valve seat and the second connection bore as well as the connection sleeve with the control member. Due to the fact that the penetration depth of the second part into the first part is adjustable, such that the stroke of the armature is adjustable, a fine adjustment of the pressure-control valve is possible during assembly. This is possible in a particular manner, when the second part is pressed into the first part. 
         [0012]    The core can further comprise a pin of non-magnetizable material that serves as a stop element for the armature and as a spring seat of a spring that resiliently supports the armature with respect to the core. 
         [0013]    Further fine adjustment is made possible by the fact that the pin is arranged in the core in an adjustable manner. 
         [0014]    The path of the magnetic field lines can be influenced by the fact that the end of the core averted from the armature has an adjustment bore in which an adjustment screw is provided. It is particularly advantageous here if the core has a substantially circumferential recess in the region of the adjustment bore on the side facing to the coil. 
         [0015]    The following is a detailed description of the present invention with reference to an embodiment and to the accompanying drawing. 
         [0016]    The pressure-control valve  1  comprises a housing  2  which is built substantially from an upper part  3  and a lower part  4 . The upper part  3  comprises an electromagnetic drive unit  5  acting upon an armature  7  arranged for axial displacement in a bearing/bearing bush  6 . The electromagnetic drive unit  5  substantially comprises a coil  8 , a core  9  and a flux guiding means  10  that is formed by a backiron  11  and a yoke  12 . The housing  2 , which is made of a plastic material, further comprises a plug  13  for connection with a control module known per se and not illustrated herein. The electromagnetic drive unit  5  acts on the armature  7  which has a valve member  14  at its end averted from the core  9 . In the present instance, the valve member  14  is connected with a control member  16  via a connection rod/valve rod  15  and is of conical shape so as to provide a linear abutment. In the present instance, the armature  7 , the valve member  14 , the connection rod  15  and the control member  16  are integral. A spring  17  biases the armature  7  to a closed position with respect to the core  9 . The spring  17  is guided by a pin  18  adapted to be arranged in an adjustable manner in the core  9  during assembly. At the same time, the pin  18  serves as an upper stop element for the armature  7 . Further, an adjustment screw  19  is provided that is arranged in an adjustment bore  20  and which allows for a fine adjustment of the electromagnetic drive unit  5  such that the path of the magnetic field lines can be influenced. In order to influence the number of magnetic field lines in the transition region to the armature  7  in a simple manner, a recess  21  is additionally provided to prevent a scattering of the magnetic field lines in the region of the adjustment screw  19  and thereby allow a linear fine adjustment during assembly. 
         [0017]    In the shown embodiment, the lower part  4  is of bipartite structure, wherein, in the first part  23 , the bearing bush  6  for the armature  7  is offset backward with respect to a connection bore  24 . The term connection bore can also include a series of bores in the lower part  4 . The connection bore  24  leads to a non-illustrated tank in which atmospheric pressure p 0  prevails. A valve seat  25  is provided below the connection bore  24  which cooperates with the valve member  14 . Instead of giving the valve member  14  a conical shape, the valve seat  25  may be given a corresponding shape. By the fact that the bearing  6  for the armature  7  is provided in the first part  23  of the lower part  4  in a manner offset rearward with respect to the connection bore  24 , an unimpeded flow is provided when the pressure-control valve  1  is opened to the tank. In the present instance, the valve seat  25  is formed by the second part  26  of the lower part  4 , which also comprises the connection sleeve  38 .The second part  26  is pressed into the first part  23 , whereby the stroke of the armature  7  becomes adjustable during assembly. The second part  26  further comprises a second connection bore  27  which, in the present instance, is connected with a consumer  28 . The control pressure p 2  of the consumer  28 , which may, for example, be a variable oil pump or a vane cell pump configured to be variable, prevails at the second connection bore. A control bore  39  is provided in the connection sleeve  38 , which includes a second bearing bush  29  in which the control member  16  is supported with low friction, the control member  16  being designed as a piston in the present case. As schematically illustrated in  FIG. 1 , the control pressure p 1  prevails at this control member  16 , which pressure represents the motor oil pressure in the present instance. 
         [0018]    In the shown embodiment, the armature further has a transversal bore  30  and a longitudinal bore  31  that provide a connection between the interior  32  and atmospheric pressure p 0 . In particular, this substantially increases safety with respect to unintentional oil leakage from the pressure-control valve  1  to the environment. The electromagnetic drive  5  is furthermore not subjected to different pressures, whereby a precise control of the armature  7  is provided. 
         [0019]    The resulting forces that result from the presence of the control pressure p 2  at the control member  16  and the valve member  14 , when the pressure-control valve  1  is closed, are compensated for by the special design of the valve rod  15  connecting the valve member  14  with the control member  16 . 
         [0020]    The pressure-control valve  1  of the present invention operates as follows. In the present case, a motor oil pump  28 , known per se, is to be controlled, which pump is designed as a variable vane cell pump. The vane cell pump  28  conveys the motor oil to the motor  33 , the excess oil being returned to the tank at atmospheric pressure p 0 . The motor oil conveyed is at a pressure p 1 . A maximum delivery volume is achieved at maximum eccentricity of the rotary axis of the vane cell pump  28 , the eccentricity being obtained by displacement of a slide  34  in the vane cell pump  28 . A minimum delivery volume is achieved when the rotary axis is centric. The slide  34  cooperates with a first control chamber  35  and a second control chamber  36 , with the pressure p 2  prevailing in both the first and second control chambers  35 ,  36 . The abutment surface of the slide  34  is, however, larger in the second control chamber  36  so that, when the pressure-control valve  1  is de-energized, the slide  34  causes maximum eccentricity and thus the greatest delivery volume (fail safe function). If a reduction in eccentricity and thus a reduction in delivery volume of the vane cell pump  28  are desired, the pressure-control valve  1  is actuated and the pressure in the control chamber  36  is appropriately reduced. The oil with the pressure p 2  is thus present at the second connection bore  27 . When an increase in delivery volume is desired, the pressure-control valve  1  can be closed; a nozzle  37  and the different surface ratio of the abutment surfaces of the slide  34  thus provide that a fast displacement of the rotary axis of the vane cell pump  28  into the eccentric position takes place. The motor oil pressure p 1  prevails at the control member  16 , whereby, in case it should be too high, the motor oil pressure is controlled even when the pressure-control valve  1  is not active. The pressure-control valve  1  is further used to discharge leakage oil which, due to leaks and movement gaps, occurs in the case of large delivery volumes. 
         [0021]    The present invention is not limited to embodiments described herein; reference should be had to the appended claims.

Technology Classification (CPC): 8