Abstract:
A two-way orifice check valve device for a hydraulic circuit is disclosed. The hydraulic circuit which controls the engagement and release of a friction element, such as a clutch, is simplified to reduce the manufacturing cost, as well as improve functioning during the engagement and release of the friction element.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a two-way orifice check valve device, and more particularly, to a two-way orifice check valve device for a hydraulic circuit, in which the control pressure is stabilized during the engagement and release of a clutch, and that simplifies the hydraulic circuit controlling the clutch.  
         BACKGROUND OF THE INVENTION  
         [0002]    Generally, in a hydraulic circuit for controlling the actuation of a friction element such as a clutch, a structure prevents the abrupt engagement of the friction element. But a conventional hydraulic circuit may include many individual check valves, orifices, pressure relief valves, and the required connecting conduits. Each of these require machining and assembly. Accordingly, the conventional hydraulic circuit is unnecessarily complicated, large, and costly.  
         SUMMARY OF THE INVENTION  
         [0003]    In accordance with a preferred embodiment of the present invention, the two-way orifice check valve for a hydraulic circuit includes an orifice check valve and a pressure relief valve in a single unit. The orifice check valve includes: a body part movably installed within a first pressure chamber of an inlet conduit; first and second orifices formed on both ends of the body part respectively; a conduit communicating between the first and second orifices; a plurality of elongate projections formed around the outside circumference of the body part, for forming a plurality of flow paths between the body part and the first pressure chamber; and an access allowing communication between the elongate projections and the conduit. The pressure relief valve includes: a second pressure chamber communicating to an outlet conduit and disposed adjacently to the first pressure chamber; and a valve element having an axial flow path disposed within the second pressure chamber and elastically supported by a return spring.  
           [0004]    In a preferred embodiment of the invention a two-way orifice check valve device includes a body slidably installed within a first pressure chamber. The body slides between a first sealing position against an inlet conduit in response to a releasing fluid flow and a moveable sealing position against a valve element in response to an engaging fluid flow. The body includes a first orifice through which the entire releasing fluid flow is directed when the body is in the first position. The body also includes a second orifice through which at least part of the engaging fluid flow is directed when the body is in the second position. A channel or a plurality of channels along the body connect to an access within the body that allows fluid flow from the channel to enter a conduit within the body. This conduit leads to the first and second orifices. The channel is dimensioned and configured to allow the body to seat against the first pressure chamber when the body is in the first position. A spring seats the valve element against a third position (adjacent the first pressure chamber) during the releasing fluid flow and during an engaging fluid flow that is at less than a relief pressure. The valve element has a flow path through which the releasing fluid flow is directed before it flows though the first orifice and through which the engaging fluid flow is directed after flowing through the second orifice. When the engaging fluid flow is greater than the relief pressure the valve element moves from the third position and allows the engaging flow to bypass the second orifice, although some of the engaging fluid flow will still flow through the second orifice. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    For fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0006]    [0006]FIG. 1 is a cross-section of the hydraulic circuit having a two-way orifice check valve according to a preferred embodiment of the present invention;  
         [0007]    [0007]FIG. 2 is a perspective view of the two-way orifice check valve of FIG. 1;  
         [0008]    [0008]FIG. 3 illustrates the path of the control pressure during the engagement of the clutch in the hydraulic circuit of FIG. 1;  
         [0009]    [0009]FIG. 4 illustrates the path of the control pressure during the release of the clutch in the hydraulic circuit of FIG. 1; and  
         [0010]    [0010]FIG. 5 illustrates the path of the high control pressure during the engagement of the clutch in the hydraulic circuit of FIG. 1. 
     
    
       [0011]    Like numerals refer to similar elements throughout the several drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]    The invention provides an apparatus that accomplishes the goals of the conventional device more efficiently, more economically, and more compactly. FIG. 1 illustrates the hydraulic circuit having a two-way orifice check valve according to a preferred embodiment of the present invention. In the present invention an orifice check valve  20  decreases the variations in the control pressure and responds to the acting direction of the control pressure between an inlet conduit IN and an outlet conduit OUT and directs that flow to either a first orifice  24  or a second orifice  26 . A pressure relief valve  40  opens for a large pressure increase to quickly engage the friction element. A cylindrical body part  22  is movably installed within a first pressure chamber P 1  of an inlet conduit IN. First and second orifices  24  and  26  are formed in both ends of the body part  22  respectively. A conduit  28  connects the first and second orifices  24  and  26 . A plurality of elongate projections  30  (FIG. 2) are formed around an outside circumference of the body part  22  for forming a plurality of flow paths between the body part  22  and the first pressure chamber P 1 . An access  32  (FIG. 2) connects the flow paths between the elongate projections  30  and the body part  22  to the conduit  28 .  
         [0013]    In the pressure relief valve  40  (FIG. 1) a second pressure chamber P 2 , disposed adjacent to the first pressure chamber P 1  communicates with an outlet conduit OUT. A valve element  44  disposed within the second pressure chamber P 2  is elastically supported by a return spring  42  and has an internal flow path  46 . The cross sectional area of the first pressure chamber P 1  is smaller than that of the second pressure chamber P 2 , while the cross sectional area of the body part  22  of the orifice check valve  20  is also smaller that that of the valve element  44  of the pressure relief valve  40 .  
         [0014]    Accordingly, the body part  22 , which is movably installed within the first pressure chamber P 1 , can enter into the second pressure chamber P 2 . The body part  22  can also press the valve element  44  against the return spring  42  into the second pressure chamber P 2 , depending on the pressure in the first pressure chamber P 1 . The cross sectional area of valve element  44  of the pressure relief valve  40  is smaller than that of the second pressure chamber P 2  to allow fluid to flow through the space between the valve element  44  and the inner circumference of the second pressure chamber P 2 .  
         [0015]    When the friction element is engaged by the control pressure in the hydraulic circuit, the following actuations occur. As shown in FIG. 3, the control pressure, which has been introduced through the inlet conduit IN into the first pressure chamber P 1 , flows through the access  32  and through the spaces between the plurality of the elongate projections  30  of the body part  22  into the body part  22 . Under this condition, the body part  22  within the first pressure chamber P 1  is pushed rightward by the control pressure to contact the valve element  44 , but the valve element  44  is elastically supported by the return spring  42  on its rear part, and therefore, the motion of the valve element  44  is hindered. The control pressure which has been introduced into the body part  22  is transmitted through the second orifice  26  into the second pressure chamber P 2 . Then the control pressure passes through the flow path  46  of the valve element  44  and through the outlet conduit OUT to be supplied to the relevant friction element.  
         [0016]    If the friction element is released, the following actuations occur, as shown in FIG. 4. That is, the control pressure, which has been introduced through the outlet conduit OUT into the second pressure chamber P 2 , passes through the axial flow path  46  to enter into the first pressure chamber P 1 . Under this condition, the body part  22  within the first pressure chamber P 1  is pushed leftward by the control pressure. The valve element  44  within the pressure chamber P 2  cannot enter into the first pressure chamber P 1 , since the cross sectional area of the first pressure chamber P 1  is smaller than that of the second pressure chamber P 2 . Thus, the valve body  44  seals against the first pressure chamber P 1 , requiring all fluid to flow through flow path  46 . The control pressure passes through the spaces between the plurality of the elongate projections  30  and through the lateral access  32  to enter into the body part  22 . The control pressure then passes through the first orifice  24  to be discharged through inlet conduit IN of the hydraulic circuit.  
         [0017]    When a large control pressure acts in the hydraulic circuit to quickly engage the friction element, the following occurs as shown in FIG. 5. The control pressure, which has been introduced through the inlet conduit IN into the first pressure chamber P 1 , passes through the plurality of the channels between the plurality of the elongate projections  30  to enter into the second pressure chamber P 2 . Under this condition, the body part  22  of the first pressure chamber P 1  is pushed rightward by the control pressure. The body part  22  partly enters the second pressure chamber P 2  by overcoming the force of the return spring  42 , resulting in the valve element  44  (elastically supported by the return spring  42 ) being pushed rightward. Accordingly, the space between the body part  22  and the shell of the first pressure chamber P 1 , and the space between the valve element  44  and the second pressure chamber P 2 , are connected. The control pressure passes through the space between the valve element  44  and the inner circumference of the second pressure chamber P 2  and out the the outlet conduit OUT to be supplied to the relevant friction element.  
         [0018]    According to the present invention as described above, an orifice check valve  20  decreases the variations in the control pressure and determines the acting direction of the control pressure between an inlet conduit IN and an outlet conduit OUT, between which the control pressure flows to the friction element. Further, a pressure relief valve  40  allows large control pressure to flow through the device to make it possible to quickly engage the friction element. This simplifies the structure so that the component space and manufacturing cost is reduced.  
         [0019]    The foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.