Hydraulic control valve assembly with diverse circuit adaptability
This is a continuation of Ser. No. 419,517, filed Nov. 28, 1973, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a hydraulic control valve assembly. In particular, this invention relates to a pre-cored valve body adaptable to provide a first valve assembly having two independent circuits, or a second valve assembly having a single circuit with an interrupted series function. 
     Conventionally, valve assemblies of the type employed in fluid systems for controlling fluid flow to a plurality of fluid motors comprise a plurality of independent valve units, typically connected in series, for directing fluid flow from a fluid supply source to operate the fluid motors associated with the respective valve units. Such fluid systems frequently have diverse valve function requirements, commonly employing, for example, valve assemblies which provide a plurality of independent circuits within a single valve housing, or which provide a single circuit having multiple interrupted series functions within a single valve housing, according to the requirements of a specific fluid system. 
     Fluid systems employing valve assemblies of both types are commonly associated with a variety of equipment, including earthworking equipment such as hydraulic excavators and motor graders. Examplary of fluid systems employing both types of valve assemblies is the three-pump hydraulic circuit for a hydraulic excavator described in U.S. Pat. Ser. No. 207,027, by Bridwell, et al filed Dec. 13, 1971, and of common assignment herewith. 
     At present, valve assemblies are conventionally manufactured as independent units having the desired valve function within each separate unit. Such manufacturing techniques require diversified casting and tooling efforts and involve relatively complicated production and distribution techniques. 
     Attempts have been made to diversify such specialized valve assemblies for more universal use. For example, the multiple spool valve assembly described in U.S. Pat. No. 3,195,571 and British Pat. No. 835,331 is provided with a carryover fitting effective, inter alia, to establish fluid communication between this and another valve assembly for example, for series operation of a plurality of fluid motors. Also, U.S. Pat. No. 2,868,227 describes a valve housing cored to permit selective blocking of the valve circuits for single or multiple use of the valve assembly. 
     While the assemblies described attempt to facilitiate single or multiple use of specialized valve units, the valve units per se are not adaptable for use according to valve function requirements of various fluid systems, and afford minimal versatility of function for use under varying system requirements. 
     BRIEF SUMMARY AND OBJECTS OF THE INVENTION 
     The invention provides a unitary valve body adaptable to provide one of two circuit arrangements having the desired valve function for a particular fluid system application. The valve body is pre-cored to provide a plurality of valve stem bores and fluid communication passages selectively communicable to provide a first valve assembly having two independent circuits and/or a second valve assembly having a single circuit with an interrupted series function. 
     It is therefore an object of this invention to provide a pre-cored valve body selectively adaptable for single or double circuit functions. 
     It is another object of this invention to provide a versatile valve body which can simply and effectively be adapted to diverse fluid system requirements. 
     It is an additional object of this invention to provide a pre-cored valve body adaptable for use according to fluid system requirements which permits simplification of standard valve production and distribution techniques for these systems. 
     Other object and advantages of the invention will be apparent from the following description and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a pre-cored valve body in accordance with the present invention; 
     FIG. 2 is a view of the valve body like FIG. 1, modified to provide a valve body for a first valve assembly having two distinct circuits; and 
     FIG. 3 is a view of the valve body like FIG. 1, modified to provide a valve body for a second valve assembly having a single circuit of three interrupted series functions. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     There is illustrated in FIG. 1 a valve body which includes a three-stem hydraulic valve body casting 10 provided with an inlet 11 and a series of parallel valve spool receiving bores 12, 13 and 14. The inlet 11 is for communicating with a pump 15 which draws fluid from a fluid tank supply or sump 17. A U-shaped tank return passage 16 communicates with a tank 17 via an outlet 18, and two central bypass passages 19 and 21. Each valve stem receiving bore 12, 13 and 14 is in communication respectively with a pair of motor passages 22 and 23; 24 and 25; and 26 and 27 respectively. 
     As shown in FIG. 1, the central bypass passages 19 and 21 are blocked from communication with each other by means of a removable wall portion 20. The wall or web 20 is removable by virtue of its being located by suitable indicies and having a thickness and configuration enabling it to be removed by a simple drill operation. It should also be noted that these passages are not provided with an outlet to the tank 17 at this time. The passage 21 is blocked by a wall portion 28 from communication with return passage 16. The valve assembly illustrated in FIG. 1 is thus selectively adaptable to either one of the valve assemblies illustrated in FIGS. 2 and 3, as desired; however, the valve assembly of FIG. 1 is not functional as illustrated without adaptation. 
     With reference to FIGS. 2 and 3, first and second modifications or adaptations of the valve assembly of FIG. 1 are illustrated, providing alternate circuitry in the valve body 10. Each of the three bores 12, 13 and 14 for operation are provided respectively with valve stems 29, 30 and 31 as shown in phantom in FIGS. 2 and 3 for control of typical excavator motor as indicated. In the functional valve assemblies illustrated in FIGS. 2 and 3, the stems 29, 30 and 31 that will be provided control fluid pressure to the motor passages 22 and 23; 24 and 25; and 26 and 27, respectively. 
     The valve assemblies of FIGS. 2 and 3 are shown with valve stems (shown in phantom) labelled for certain control functions for application, for example, with a hydraulic excavator (not shown), but it is understood that these control functions are variable according to the specific application, and that the control functions indicated in FIGS. 2 and 3 are included by way of illustration only. 
     With particular reference to FIG. 2, the valve assembly of FIG. 1 is shown modified to provide two distinct circuits comprising a first interrupted series circuit including the valve stems 29 and 30 and a second independent circuit including the valve stem 31. The valve assembly of FIG. 1 is adapted for this function by providing an outlet 32 in the bypass passage 19, to render the first circuit functional. The outlet is formed by drilling a hole at a pre-determined indicated position through the outer wall of the housing into the passage 19. The outlet 32 may be either communicated with the tank 17, or communicated with another valve assembly so that fluid from the first interrupted series circuit valve stems 29 and 30 may be combined with such other valve assembly. The valve assembly of FIG. 1 is further adapted for this function by providing the bore 14 with an inlet port 33, simply by drilling through the housing, and by providing the bypass passage 21 with an outlet port 34 communicating the passage 21 with the return passage 16 and the tank outlet 18. The outlet port 34 is drilled in wall portion 28 between the bypass passage 21 and the tank return passage 16, providing communication between these two passages. The outlet port 34 may be formed by inserting a drill through outlet port 18 to engage wall 28. 
     The inlet port 33 is then connected to an independent fluid pump (not shown), and the circuit including the valve stem 31 is independent of the circuit including the valve stems 29 and 30. 
     With particular reference now to FIG. 3, the valve assembly of FIG. 1 is shown modified and adapted to provide a single circuit with the three valve stems 29, 30 and 31 in interrupted series arrangement. The valve assembly of FIG. 1 is adapted for this function by providing a communicating passage 35 between the bypass passages 19 and 21, and by providing an outlet port 36 in the bypass passage 21. 
     The communicating passage 35 is preferably formed by drilling the housing at a pre-determined indicated position to remove wall 20 between the bypass passages 19 and 21. The outer end of hole 35 is then plugged where it penetrates the valve body 10. The outlet port 36 is similarly formed by drilling and may be connected to another valve to provide high pressure carryover fluid to such other valve circuit. 
     Other variations and modifications are possible from the basic valve body and the illustrated modifications. For example, passages 34 and 36 may both be provided in both FIG. 2 and FIG. 3 and the one not needed for the particular circuit may be plugged in a suitable manner. 
     Thus, from the above description it is seen that I have provided a valve body that is readily adaptable to diverse circuit requirements simply by drilling holes to provide communicating ports at pre-selected positions in the valve body. This invention provides means whereby only a single valve body need be stocked to supply a number of different circuit requirements.