Abstract:
A valve assembly has a single piece body that houses a plurality of hydraulic valves. Each valve includes a spool which controls the flow of fluid between a pair of work ports in one side of the body and a pump inlet and a tank outlet. The valves are operated by selectively applying pressurized fluid to one end or the other of the spool. That pressure is provided by a conduit or a pilot valve that is attached to a control port in the one side of the body. Because the majority of the connections to the valve assembly are made to the one side of the body access is only required to that side.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hydraulic valves, and more particularly to assemblies having a common monolithic block in which a plurality of individually operable valves are formed. 
     2. Description of the Related Art 
     Construction equipment have movable members which are operated by hydraulic cylinder/piston arrangements. For example, a skid steer loader has a boom that is used to raise and lower an implement, such as a bucket for moving dirt. Hydraulic actuators are provided for raising and lowering the boom and for tilting the implement with respect to the boom. An additional hydraulic circuit often is provided for auxiliary equipment. 
     The flow of fluid to and from each hydraulic actuator typically is controlled by a spool valve which in turn is controlled by a pilot valve. In this installation, a common valve body, known as a monolithic block, or monoblock, has a plurality of bores extending between two opposing surfaces, a separate control spool is received in each bore. Movement of the control spool opens and closes passages between the actuator and hoses that connect to a pump and a tank. Other hydraulic lines are attached to the openings at each end of the bores. These hydraulic lines lead to the pilot valves located within the cab of the skid steer loader. When the user desires to activate a particular function on the equipment, the pilot valve associated with that function is operated to vary the hydraulic pressure applied to the ends of the related control spool. Increasing the pressure at one end of the bore, causes the spool to move toward the other end which positions the spool to open a passage between the pump and a work port connected to the actuator for the desired function. Applying pressure to the other end of the bore moves the spool valve in the opposite direction to a open a passage between the work port and the tank of the hydraulic system. When the pilot valve is released, both ends of the bore are connected to the tank thereby causing the control spool to assume a center position. In the case of a hydraulic cylinder, bidirectional movement of a more complex control spool connects one cylinder chamber to the pump or tank and the other cylinder chamber to the other one of the pump or tank. 
     As noted previously, a plurality of control spools are contained in bores in the monolithic block. Often it is difficult to connect all the various hydraulic lines for the pump, the tank, each actuator, and the pilot valves to a compact valve assembly block. In addition, pressure relief valves and other mechanisms also have to be provided in the hydraulic circuits. As a consequence, mechanics-servicing the machinery often have difficulty in disconnecting and reconnecting the various hydraulic lines attached to the valve block. 
     There is a current trend with respect to construction equipment away from manually operated or hydraulically piloted valves toward electro-hydraulically controlled valves. Electrical control simplifies the hydraulic plumbing as control valves do not have to be located in or near the operator cab. This change in technology also facilitates computerized control of various machine functions, to either assist the operator or prevent dangerous conditions from occurring. This too has created difficulties in that the control of a given piece of equipment may be a combination of manually operated hydraulic circuits and electrically operated ones. This further complicates the arrangement of hydraulic valves. 
     SUMMARY OF THE INVENTION 
     A hydraulic valve assembly includes a compact body that has two primary sides and at least two opposing secondary sides extending between the primary sides. A plurality of valve bores extend between the two opposing secondary sides, and an inlet and an outlet for the assembly communicate with the valve bores. Each valve bore also communicates with a different pair of work ports that open through one primary side. The body further includes a plurality of first control ports each extending from the one primary side to one end of a different one of the plurality of valve bores, and a plurality of second control ports each extending from the same primary side to another end of a different one of the plurality of valve bores. 
     A separate control spool is located in each of the valve bores for controlling flow of hydraulic fluid between the work ports and the inlet and outlet. The control spool also defines a chamber at each end of the respective valve bore and each chamber communicates either a first control port or a second control port. A plurality of pilot pressure control elements each received in a different one of the first control ports and second control ports to define pressure in a respective chamber of an associated one of the plurality of valve bores. In the preferred embodiment of the valve assembly, each pilot pressure control element is either a fluid conduit or an electrically operated valve. 
     By applying pressure at one end or the other end of the bore, the spool is moves to different positions in the bore. This causes the spool to form various passages between the inlet and outlet and the two work ports coupled to that bore. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of a valve assembly according the present invention; 
     FIG. 2 is a plane view of one side of the valve assembly; 
     FIG. 3 is a plane view of another side of the valve assembly; 
     FIG. 4 is a cross-sectional view taken along line  4 — 4  in FIG. 2; and 
     FIG. 5 is a schematic representation of the hydraulic circuit of the valve assembly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With initial reference to FIGS. 1 through 3, a hydraulic valve assembly  10  has a body  12  form of a single piece of metal having a first primary side  14  and a second primary sided  15 . The body also has first, second, third, and fourth secondary sides  16 ,  17 ,  18  and  19 , respectively. An inlet  20  is located in the first primary side  14  for connection to the outlet of a hydraulic pump that supplies pressurized fluid for operating the hydraulic circuit of which the valve assembly is a part. An outlet  22  is provided in the body, and extends into the third secondary side  18 . The second secondary side  17  has two threaded apertures  21  for mounting the hydraulic valve assembly  10  to the equipment being controlled. 
     The valve body  12  has three separately operable valves therein each having a pair of work ports on the first primary side  14  for connecting three actuators, such as cylinders to the valve assembly. The first valve has work ports  24  and  25 , the second valve is served by work ports  26  and  27 , work ports  28  and  29  are associated with the third valve. Each valve is operated by pressure applied at a pair of control ports located in the first primary side  14 . Specifically, the first valve is coupled to control ports  30  and  31 , the second valve has control ports  32  and  33 , while the third valve assembly is associated with control ports  34  and  35 . 
     Referring to FIG. 4, the housing  12  has three bores  41 ,  42  and  43  extending between the first and third secondary sides  16  and  18 , respectively. Each bore has a plurality of channels which communicate with the various ports in the body. For example, the inlet  20  communicates with a through-neutral passage  45  that leads to each bore. The outlet  22  communicates with an internal tank passage  40  which extends to a pair of channels on opposite sides of the through-neutral passage  45  in each bores  41 - 43 . Work ports  24  and  25  extend from the first primary surface  14  into the first bore  41 , and work ports  26  and  27  extend to the second bore  42 . Work ports  28  and  29  extend into the third bore  43 . 
     A first control spool  44  is slidably located within the first bore  41  thereby defining the end chambers  54  and  56 . The ends of the first bore  41  are closed by simple plugs  50  and springs  52  bias the first control spool  44  away from those plugs. A second control spool  46  is similarly received in the second bore  42  and defines the end chambers  58  and  60 . The ends of the second bore  42  are closed by another pair of plugs  51  and additional springs  52  bias the second control spool  46  away from those plugs  51 . A third control spool  48  slides within the third bore  43 , the ends of the which are closed by end caps  84  and  86 . The third control spool  48  has four control states and thus is longer than the first and second spools  44  and  46  which have three control states. The ends of the third bore  43  are closed by end caps  84  and  86  which accommodate the travel of the longer third control spool and house the associated return springs. The forces exerted by the springs center the respective control spool-in a closed state within its respective bore when the associated valve is not activated. The first and second spools  44  and  46  optionally may be fitted with larger spring packs or detent latching devices. 
     It should be noted that end plugs  50  and  51 , used in the first and second bores  41  and  42 , eliminate the need for standard elongated end caps, such as  84  and  86 , which extend significantly beyond the sides of the valve body  12 . 
     FIG. 5 illustrates the hydraulic circuit formed within the valve assembly  10 . A pump  66  supplies pressurized hydraulic fluid to the inlet  20  of the body  12  and the outlet  22  of the body is connected to the system tank  68 . A primary pressure relief valve  67 , also visible in FIGS. 1 and 4 is positioned to relieve the pressure at inlet  20  to the internal tank passage  40  and outlet  22  in the event that the inlet pressure exceeds a given level. The inlet  20  and outlet  22  are coupled by interior channels in the body to the three control valves  71 ,  72  and  73 . The first control valve  71  is formed by the first bore  41  and the first control spool  44  and is a three position valve which controls the flow of fluid to and from a pair of auxiliary work ports  24  and  25 . Work port  24  is connected to a pressure relief valve  74  which relieves excessive work port pressure to the tank outlet  22 . As seen in FIG. 2, the pressure relief valve  74  is located on the first secondary side  16  of the body  12  below the end plug  50  for the first bore  41 . 
     The first valve  71  is controlled by a pair of electrically operated solenoid valves  76  and  78 . The first solenoid valve  76  is mounted in control port  30  thereby selectively connecting the chamber  54  at one end of the first bore  41  to either the tank outlet  22  or a pilot pressure inlet port  75  on the third valve body side  18  (see FIG.  1 ). The second solenoid valve  78  is mounted in control port  31  and selectively couples the control chamber  56  at the other end of the first spool bore  41  to either the tank outlet  22  or the pilot pressure inlet port  75 . In the normal, or de-energized, state of these solenoid valves  76  and  78 , the respective chamber  54  and  56  of the valve bore  41  is connected to tank. In the energized state, the solenoid valve  76  or  78  couples the respective bore chamber  54  or  56  to the pilot pressure inlet port  75  thereby applying a relatively high pressure which moves the first control spool  44  away from that end of the first bore  41 . Thus, the first valve  71  is moved in opposite directions by energizing one of the solenoid valves  76  and  78 . 
     The second valve  72  controls the flow of hydraulic fluid to and from work ports  26  and  27  in response to pressures at control ports  32  and  33 . These work ports are connected to a cylinder (not shown) which controls the implement connected to the boom of the exemplary skid steer loader. The control ports  32  and  33  are machined to accept a fluid conduit (e.g. hydraulic hose fitting  37  in port  32 , FIG. 1) which leads to a remote pilot valve that is manually operated by the user of the hydraulic equipment. Alternatively, a hose fitting from a remote pilot valve can be connected to the end openings of one or more of the spool bores  41 - 43  in place of the end caps  50  and  51 . In that case the control ports associated with those spool bores  41 - 43  would be plugged. Operation of the hydraulic valve in one direction applies pressurized fluid to one of the control ports  32  or  33  and movement of the pilot valve in the opposite direction applied pressurized fluid to the other control port  33  or  32 . This produces in bidirectional movement of the second control spool  46 . Both of the work ports  26  and  27  have individual pressure relief valves  80  and  82 , respectively. As shown in FIG. 2, the relief valve  80  associated with work port  26  is received in an aperture that is located on the first secondary side  16  of the valve body  12  below the end plug  51  for the associated second valve  72 . The other relief valve  82  for work port  27  is located in an opening through the third valve body surface  18 , shown in FIG. 3, at a location below the other end plug  51  for the second valve. The inner ends of the relief valves  80  and  82  communicate with the tank passage  40  through the valve body  12  as seen in FIG.  4 . 
     The third control valve  73  is a four position type valve which regulates the flow of fluid between work ports  28  and  29  which in the example of a skid steer loader leads to the cylinder for the boom. Specifically, work port  28  connects to the base-side chamber of the cylinder and is pressurized to raise the boom, while work port  29  connects to the rod-side chamber and is pressurized to lower the boom. The third control valve  73  is formed by the third spool  48  and its associated third bore  43  within the valve body  12 . The chambers  62  and  64  at opposite ends of the third spool are connected to control ports  34  and  35 , respectively. These control ports  34  and  35  have been machined to accept a standard fitting of a hydraulic hose that connects to another manual pilot valve in the cab of the skid steer loader. As with the second control valve  72 , operation of this other pilot valve by the user moves the third spool  48  in opposite directions into positions that control the flow of fluid to and from the work ports  28  and  29 . 
     Work port  28  is connected to another pressure relief valve  88  which relieves excessive work port pressure to the tank outlet  40  and  22 . As seen in FIG. 2, this pressure relief valve  88  is located on the first secondary side  16  of the body  12  below the end cap  84  for the associated third bore  43 . 
     Referring to FIG. 5, separate load check valves  91 ,  92  and  93  are located in the passage in the body  12  from pump inlet  20  to each of the valves  71 ,  72  and  73 , respectively. These load check valves are located under plugs  94 ,  95  and  96  in holes in the first primary side  14  of the valve body  12  as shown in FIG.  1 . Another check valve  98  associated with the boom base work port  28  is located in a cavity behind plug  87 . which seals an opening on the fourth secondary side  19  as seen in FIG.  1 . This check valve prevents unwanted back-flow associated with the main valves series circuit. 
     With reference again to FIG. 5, the pilot pressure inlet port  79  communicates with the supply passage  77  which leads through the valve body to another port  75  at the opposite side as shown in FIG.  2 . Thus either port  75  or  79  may be used to couple a hose that-supplies pressurized fluid to the pilot solenoid valves  76  and  78 . An optional accumulator can be connected at the other of these ports  75  or  79  to maintain a pressurized supply of hydraulic fluid for use by the solenoid valve  76  and  78 . This option supplies the system hydraulic plumbing on the skid steer loader. 
     The design of the valve assembly  10  has great flexibility in that the same monolithic body  12  can be machined differently so that the control ports  30 - 35  can accept either a solenoid control valve or the fitting of a hydraulic hose from a remote pilot valve. This enables different types of control mechanism to operate the three valves within the valve assembly  10 . For example, if the second control valve  72  is to be controlled by another pair of solenoid valves, the associated control ports  32  and  33  would be machined to accept the stem of that type of valve, instead of a hose fitting. In addition, a passage would be drilled from the control ports  32  and  33  to the passage  77  leading to the pilot pressure inlet port  79  (FIG.  5 ). The design of the valve body allows such additional passages to be formed to accommodate various combinations of electrohydraulic and conventional pilot valve operation of each of the control valves  71 - 73 . 
     The valve assembly  10  provides simplified connectivity over that found in previous monolithic valve blocks and sectional spool valves. In particular all the work ports and control ports are located on the same primary surface  14  of the valve body for easy connection of the hoses and solenoid valves. The pilot pressure inlet port  79  communicates with a passage  77  through the valve body, which leads to another port  75  at the opposite side of the valve body  12  as shown in FIG.  2 . Thus, either port  75  or  79  may be used to couple a hose that supplies the pilot pressure to the valve body, and the other pilot pressure port can be used to couple to an accumulator to maintain a supply of that pilot pressure for use by the solenoid valve  76  and  78  and other similar optional solenoid valves.