Abstract:
A cooling system for a work machine may comprise a reservoir configured to hold a supply of fluid, a source of pressurized fluid and a valve configured to receive the pressurized fluid from the source of pressurized fluid. A first working unit and a second working unit may be connected to the valve in parallel. One of The first and second working units may be adapted to receive pressurized fluid on a priority basis from the valve. The first and second working units may be fluidly connected to the reservoir by a circulation conduit and may be connected to a first heat exchanger by a bypass conduit. The bypass conduit may be configured to pass only a portion of the fluid flow to be passed from the first and second working units to the first heat exchanger. The first heat exchanger may be fluidly connected to the reservoir and may be adapted to pass the portion of the fluid flow to the reservoir.

Description:
RELATION TO OTHER PATENT  
       [0001]     This application claims the benefit of prior provisional patent application Ser. No. 60/729,740 filed Oct. 24, 2005. 
     
    
     TECHNICAL FIELD  
       [0002]     The present disclosure relates generally to a cooling system, more particularly, to a cooling system for a work machine.  
       BACKGROUND  
       [0003]     Generally a work machine may be provided with a cooling device such as a radiator for cooling an engine, and/or an oil cooler for cooling hydraulic fluid and/or an oil radiator for cooling transmission oil to prevent overheating and/or system failure.  
         [0004]     A work machine is generally configured with three independent cooling systems as set forth above. One example of such a cooling systems is disclosed in the U.S. Pat. No. 4,535,729 to Faylor issued Aug. 20, 1985.  
         [0005]     The &#39;729 patent discloses an integrated cooling system for cooling a vehicle engine, transmission oil, and auxiliary hydraulic function oil. A first oil cooler has an oil intake and outlet in communication with and for circulating the transmission oil in the cooler. The cooler has a connection to the first section for transferring coolant from the latter to the first oil cooler. A second oil cooler has an oil inlet and outlet in communication with and for circulating auxiliary hydraulic oil through the cooler that the latter cooler has a connection to the coolant in the second section for transferring coolant from the second section to the second cooler. The first and second coolant discharge conduit means receive the respective coolant from the first and second coolers and are connected to the intake of the pump.  
         [0006]     In the &#39;729 patent, all of the hydraulic oil flows through the second oil cooler cause a low start-up efficiency especially when the temperature is low. During the hydraulic system in full operation, because of lack of sufficient heat exchange with the second cooler, the temperature of the hydraulic system cannot be sufficiently reduced and cause overheating and/or system failure. The three independent cooling systems also occupy more space on the work machine.  
         [0007]     The disclosed cooing system for a work machine is directed to overcoming one or more of the problems outlined above with respect to work machine cooling system.  
       SUMMARY OF THE INVENTION  
       [0008]     One aspect of the present disclosure may include a cooling system for a work machine. The cooling system may comprise a reservoir configured to hold a supply of fluid, a source of pressurized fluid and a valve configured to receive the pressurized fluid from the source of pressurized fluid. A first working unit and a second working unit may be connected to the valve in parallel. One of The first and second working units may be adapted to receive pressurized fluid on a priority basis from the valve. The first and second working units may be fluidly connected to the reservoir by a circulation conduit and may be connected to a first heat exchanger by a bypass conduit. The bypass conduit may be configured to pass only a portion of the fluid flow to be passed from the first and second working units to the first heat exchanger. The first heat exchanger may be fluidly connected to the reservoir and may be adapted to pass the portion of the fluid flow to the reservoir.  
         [0009]     According to another aspect, the present invention is directed toward a method of operating a cooling system. The method may comprise pressurizing fluid, directing the fluid from a reservoir through a fluid pressurized source to a valve. The fluid may be directed to a first working unit and a second working unit in parallel. A one of the first and second working units may be adapted to receive pressurized fluid on a priority basis from the valve. The fluid may be passed from the first and second working units to the reservoir by a circulation conduit. A portion of the fluid may be directed from the first and second working units by a bypass conduit to a first heat exchanger. The portion of the fluid may be directed from the first heat exchanger to the reservoir.  
         [0010]     According to another aspect, the present invention is directed toward a work machine may have a first cooling system that may have a first heat exchanger, a second cooing system that may have a second heat exchanger and a third cooling system that may have a third heat exchanger. The first cooling system may comprise a reservoir configured to hold a supply of fluid, a source of pressurized fluid and a valve configured to receive the pressurized fluid from the source of pressurized fluid. A first working unit and a second working unit may be connected to the valve in parallel. One of The first and second working units may be adapted to receive pressurized fluid on a priority basis from the valve. The first and second working units may be fluidly connected to the reservoir by a circulation conduit and may be connected to a first heat exchanger by a bypass conduit. The bypass conduit may be configured to pass only a portion of the fluid flow to be passed from the first and second working units to the first heat exchanger. The first heat exchanger may be fluidly connected to the reservoir and may be adapted to pass the portion of the fluid flow to the reservoir. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  illustrates a functional block diagram of cooling system for a work machine incorporating certain disclosed embodiments;  
         [0012]      FIG. 2  illustrates another functional block diagram of cooling system for a work machine incorporating certain disclosed embodiments;  
         [0013]      FIG. 3  is a cross-sectional linkage structure illustrating a bypass conduit connecting to a circulation conduit.  
         [0014]      FIG. 4  is a diagrammatic cross-sectional structure of a cooler with a radiator for a work machine. 
     
    
     DETAILED DESCRIPTION  
       [0015]     Reference will now be made in detail to exemplary embodiments, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
         [0016]     Referring to  FIG. 1  and  FIG. 2 , they illustrate two embodiments of cooling systems of a work machine. The work machine may refer to any type of mobile machine that performs some type of operation connected to a particular industry, such as mining, construction, farming, transportation, etc. and operates between or within work environments (e.g., construction site, mine site, power plants, on-highway applications, etc.). Work machines include on-highway vehicles, commercial machines, such as trucks, cranes, earth moving vehicles, mining vehicles, backhoes, material handling equipment, farming equipment, marine vessels, aircraft, and any type of movable machine that operates in a work environment.  
         [0017]     As shown in  FIG. 1  and  FIG. 2 □ the work machine may include a steering and implement hydraulic (a first) cooling system  600 , an engine (a second) cooling system  400  and a transmission (a third) cooling system  500 . The cooling systems can be set up according to practical practice, for example to choose one or more of the cooling systems set forth above.  
         [0018]     The engine cooling system  400  may include an engine unit  40 , a circulating pump  41 , a thermostat valve  43 , a lube cooler  42  and a radiator  10 . The engine unit  40  may be connected to the thermostat valve  43 . The thermostat valve  43  may be connected to the radiator  10  and the radiator  10  may be connected to circulating pump  41 . The circulating pump  41  may be connected to a lube cooler  42  and the engine unit  40  in series. A bypass conduit  44  may be connected to thermostat  43  and the circulating pump  41 . The above-mentioned components may form a cooling circuit  400 ′, which is indicated by the arrows, of the engine cooling system.  
         [0019]     The transmission cooling system may include a cooler  11  that may be connected to the low portion of the radiator  10 , a transmission with oil tank  50 , a transmission pump  51 , a torque converter  52 , an oil filter  53  and a valve  54 . The transmission with oil tank  50  may be connected to a transmission pump  51  by circulation conduit  501 . Circulation conduit may be divided into two branches  502 ,  506  after the transmission pump  51 . One branch conduit  506  may be connected to the valve  54  and then connected to the transmission with oil tank  50 . Another branch conduit  502  may be connected to torque converter  52  and the transmission oil filter  53  in series. The transmission oil filter  53  may be connected to the cooler  11 . The cooler  11  may be connected to the transmission with oil tank  50 . The transmission may include gears and clutch as disclosed in the prior art.  
         [0020]     Referring to  FIG. 4 , the cooler  11  may have a bottom compartment  13  which may be connected to the lower portion of a water radiator  10 . A core  12  may be disposed in the bottom compartment  13 . The core  12  may have an inlet  12   a  and an outlet  12   b  for the transmission oil or the hydraulic fluid passing through. An outlet port  16  may be connected to the bottom compartment  13 .  
         [0021]     The steering and implement hydraulic cooling system may include: a cooler  20  of the fluid to air type, a hydraulic fluid tank (reservoir)  60 , a hydraulic fluid filter  61 , a fluid pressurizing source (pump)  62 , a priority valve  63 , an implement hydraulic unit  66  and a steering unit  6 . The steering unit  6  may comprise a steering valve  64  and a steering cylinder  65  that may form a loop by circulation conduits  608 ,  609 . The hydraulic fluid tank  60  may be connected to the pump  62  and priority valve  63  in series by circulation conduits  601 ,  602 . The circulation conduit may be divided into two branch conduits from the priority valve  63 . One branch conduit  605  may be connected to the implement hydraulic unit  66  and another branch conduit  603  may be connected to the steering unit  6  in parallel relation. A conduit  606  connected to the implement hydraulic unit  66  and a conduit  604  connected to the steering valve  64  may be joined into a conduit  610  and may be connected to the hydraulic fluid filter  61 . The hydraulic fluid filter  61  may be connected to the hydraulic fluid tank  60  by a circulation conduit  67  and be connected to the cooler  20  by a bypass conduit  68 . The cooler  20  may be fluidly connected to the fluid tank  60  by a circulation conduit  607 .  
         [0022]     Referring to  FIG. 1  and  FIG. 2 , the cooler  20  may be disposed inboard of the first radiator  10 . A shroud  33  with an inlet may be positioned adjacent to the first radiator  10 . A fan  30  may be positioned in the inlet of the shroud  33 .  
         [0023]     Further referring to  FIG. 2 , a thermostat valve  70  may be positioned in the line of the bypass conduit and adjacent to the cooler  20 , which may be movable to the hydraulic fluid passing position in response to the temperature reaching a predetermined temperature.  
         [0024]     Referring to  FIG. 4 , an orifice  69  defined by an outlet port  67 ′ of the circulation conduit may be positioned in the line of the bypass conduit  68 . The outlet port  67 ′ may be connected to one end  68 ′ of the bypass conduit  68 . The diameter d of the outlet port  67 ′ may be smaller than the diameter D of the bypass conduit. The outlet port may be integrally formed with the circulation conduit. The outlet port may be formed by other structure known in the art.  
       INDUSTRIAL APPLICABILITY  
       [0025]     Referring to  FIG. 1 , in operation, when the cooling water temperature in the radiator reaches a certain temperature, the thermostat valve  43  may open the bypass conduit  44  by a control circuit. Pump  41  may pump water from engine unit  40  through a conduit  401 , the thermostat valve  43 , bypass  44 , pump  41 , a conduit  402 , the lube oil cooler  42  and return to the engine unit  40  through a conduit  403 . The lube oil cooler  42  may be fluidly connected to the engine unit  40  by an inlet conduit  404  and an outlet conduit  405  to form a circulation of the engine lube oil. The opening thermostat valve may prevent the cooling water from circulating through the radiator  10  in order to bring the cooling water temperature up to operating temperature, and such that when the cooling water temperature may be above a certain temperature, the thermostat valve may close the bypass conduit  44  by the control circuit. Pump  41  may pump water from engine unit  40  through the conduit  401 , the thermostat valve  43 , a conduit  406 , the radiator  10 , a conduit  407 , the pump  41 , the conduit  402 , the lube oil cooler  42  and returns to the engine unit  40  through the conduit  403 . The lube oil cooler  42  may be fluidly connected to the engine unit by an inlet conduit  404  and an outlet conduit  405  to form a circulation of the engine lube oil. This circulation may allow the cooling water to circulate through the radiator to reduce the cooling water temperature to a desired operating temperature.  
         [0026]     The cooling method of the transmission cooling system  500  may include passing the transmission oil from transmission oil tank  50  through a conduit  501 , the pump  51 , a conduit  502 , the torque converter  52 , a conduit  503 , the oil filter  53  and a conduit  504  to the cooler  11 . The transmission oil may be passed from the cooler  11  through a conduit  505  to the transmission with oil tank  50 . When the pressure in the pump may reach a certain value, a part of the transmission oil may be passed from the pump  51  through a conduit  506  to the valve  54  and then to the transmission with oil tank  50  through a conduit  507 .  
         [0027]     In the cooler  11 , water cooled in the radiator  10  may go down through conduits to the bottom compartment  13 . The transmission oil heated in operation may be passed into the core  12  through inlet  12   a . The transmission oil may exchange heat with the cooled water that may come from the radiator. After releasing heat to the water in the bottom compartment  13 , the transmission oil may be passed out of the core  12  through the outlet  12   b  and return to the transmission with oil tank  50  through the conduit  505 . During this circulation, transmission oil exchange heat with water in the cooler  11  to reduce the transmission oil temperature to a desired operating temperature.  
         [0028]     The cooling method of the steering and implement hydraulic cooling system may include pumping the hydraulic fluid from the hydraulic fluid tank  60  to the hydraulic oil pump  62  through a conduit  601 , then to the priority valve  63  through a conduit  602 . The hydraulic fluid may be passed into implement hydraulic unit  66  through one branch conduit  605  and then to the filter  61  through a conduit  606 . When the work machine in steering operation, the hydraulic fluid may be passed from priority valve  63  to the steering unit  6  through a branch conduit  603 , prior to be passed the implement hydraulic unit  66 , and then to the filter  61  through a conduit  604 . As shown in  FIG. 1  and  FIG. 2 , the conduit  604  and  606  may be joined into a conduit  610  before connected to the filter  62 . A portion of hydraulic fluid may be passed from the filter  61  to the fluid tank  60  through the circulation conduit  67 . The other portion of hydraulic fluid may be passed to the cooler  20  through the bypass conduit  68  and then be returned to the hydraulic tank  60  through a conduit  607 . In the steering unit  6 , hydraulic fluid may be passed to steering cylinder  65  from the steering valve  64  through a conduit  608  and be returned to the steering valve  64  through a conduit  609 , which may form a circulation of the steering unit. Within this circulation, hydraulic oil may exchange heat with the air in the cooler  20  to reduce the hydraulic fluid temperature to a desired operating temperature.  
         [0029]     Further referring to  FIG. 2 , the operation of the engine cooling system  400  and the transmission cooling system  500  in  FIG. 2  may be the same as in  FIG. 1 .  
         [0030]     The cooling method of the steering and implement hydraulic cooling system may operate like following. When the hydraulic fluid temperature may be blow a certain temperature, the thermostat valve  70  may be closed by a control circuit. The hydraulic fluid may be pumped from the hydraulic fluid tank  60  to the hydraulic oil pump  62  through a conduit  601 , then to the priority valve  63  through a conduit  602 . A portion of the hydraulic fluid may be passed from priority valve  63  to the steering unit  6  through a branch conduit  603  and then to the filter  61  through a conduit  604 . The other portion of the hydraulic fluid may be passed to implement hydraulic unit  66  through another branch conduit  605  and then to the filter  61  through a conduit  606 . As shown in  FIG. 1  and  FIG. 2 , the conduit  604  and  606  may be joined into a conduit  610  and connected to the filter  62 . The hydraulic fluid may be passed from the filter  61  to the fluid tank  60  through the circulation conduit  67 . In the steering unit  6 , the hydraulic fluid may be passed into steering cylinder  65  from the steering valve  64  through a conduit  608  and be returned to the steering valve  64  through a conduit  609 , which may form a circulation of the steering unit.  
         [0031]     When the hydraulic fluid temperature may reach a certain temperature, the thermostat valve  70  may be opened by a control circuit. The hydraulic fluid may be pumped from the hydraulic fluid tank  60  to the hydraulic oil pump  62  through a conduit  601 , then to the priority valve  63  through a conduit  602 . The hydraulic fluid may be passed into implement hydraulic unit  66  through one branch conduit  605  and then to the filter  61  through a conduit  606 . When the work machine in steering operation, the hydraulic fluid may be passed from priority valve  63  to the steering unit  6  through a branch conduit  603 , prior to be passed the implement hydraulic unit  66 , and then to the filter  61  through a conduit  604 . As shown in  FIG. 1  and  FIG. 2 , the conduit  604  and  606  may be joined into a conduit  610  and be connected to the filter  62 . A portion of hydraulic fluid may be passed from the filter  61  to the fluid tank  60  through the circulation conduit  67 . The other portion of hydraulic fluid may be passed to the cooler  20  by a bypass conduit  68  and then be returned to the hydraulic tank  60  through a conduit  607 . In the steering unit  6 , hydraulic fluid may be passed to steering cylinder  65  from the steering valve  64  through a conduit  608  and return to the steering valve  64  through a conduit  609 , which may form a circulation of the steering unit. Within this circulation, hydraulic oil may exchange heat with the air in the cooler  20  to reduce the hydraulic fluid temperature to a desired operating temperature.  
         [0032]     During the operation of the work machine, the fan  30  may blow air through both the first radiator  10  and the cooler  20  for heat exchange, which may reduce the temperature of the engine system, the transmission system and the steering and implement hydraulic system.  
         [0033]     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed the radiator and work machine. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed sealing box and pressured cab. It is intended that the specification and examples be considered as exemplary only, with a true scope may be indicated by the following claims and their equivalents.