Abstract:
A fluid heating system for a work vehicle including a pressurized fluid circuit, a pump, and a fan for cooling fluid of the fluid circuit. Pressurized fluid of the fluid circuit provided to the fan results in fan operation. A speed of the fan corresponds to a flow rate of pressurized fluid of the fluid circuit provided to the fan. A control device is in fluid communication with the fluid circuit, the control device operable between a first position and a second position. The first position of the control device results in substantially all of the fluid of the fluid circuit being provided to the fan. The second position of the control device results in at least a portion of the fluid of the fluid circuit bypassing the fan, thereby reducing the speed of the fan while increasing a pressure magnitude and increasing a temperature of the fluid system.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to fluid heating systems, and the use thereof, and, more particularly, to vehicle fluid heating systems. 
       BACKGROUND OF THE INVENTION 
       [0002]    In cold climates, it is important to minimize the amount of time needed to warm a vehicle to operating temperature. More specifically, the temperature of the hydraulic oil must be increased to a minimum operating temperature before implement operation, such as a loader, is allowed. This oil can be heated by the operator manually by cycling the loader circuit, but this activity can be both fatiguing and time-consuming to the operator. Alternatively, the vehicle could include a system or arrangement on the vehicle to warm the hydraulic oil already being automatically circulated, such as with a fixed-flow cooling fan circuit. 
         [0003]    A drawback of a fixed-flow cooling fan circuit is that it is pressure-controlled. That is, a fixed amount of flow supplies the circuit via a gear pump, and a variable pressure-relief valve defines the inlet pressure to the hydraulic cooling fan. In response to an increase in the pressure in the cooling fan circuit, the speed of the cooling fan likewise increases, providing undesirable cooling to the same hydraulic oil that is to be heated. In other words, it has not been possible to generate a high system pressure (which would most quickly heat the oil) without also operating the cooling fan at a high speed. 
         [0004]    Accordingly, it would be desirable to provide an inexpensive pressure-controlled fixed-flow cooling fan circuit to operate at a high pressure without increasing the speed of the cooling fan in order to minimize time associated with heating hydraulic oil associated with implement operation of a work vehicle. It would additionally be desirable for the fan circuit to operate essentially independently of an operator (an automatic process) that generates large amounts of pump flow at a high pressure, and operates independently of or without resulting in external movement of the implement. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention relates to a fluid heating system for a work vehicle including a pressurized fluid circuit having a pump and a fan for cooling pressurized fluid of the fluid circuit. Pressurized fluid of the fluid circuit provided to the fan results in fan operation. A speed of the fan corresponding to a flow rate of pressurized fluid of the fluid circuit provided to the fan. A control device is in fluid communication with the fluid circuit, the control device operable between a first position and a second position. The first position of the control device results in substantially all of the pressurized fluid of the fluid circuit being provided to the fan. The second position of the control device results in at least a portion of the pressurized fluid of the fluid circuit bypassing the fan, thereby reducing the speed of the fan while increasing a pressure magnitude of and increasing a temperature of the fluid system. 
         [0006]    The present invention further relates to fluid heating system for a work vehicle including a pressurized fluid circuit having a pump and a fan for cooling pressurized fluid of the fluid circuit. Pressurized fluid of the fluid circuit provided to the fan results in fan operation, the fluid circuit operating independent of or not resulting in external movement of an implement. A speed of the fan corresponds to a flow rate of pressurized fluid of the fluid circuit provided to the fan. A control device is in fluid communication with the fluid circuit, the control device operable between a first position and a second position. The first position of the control device results in substantially all of the pressurized fluid of the fluid circuit being provided to the fan. The second position of the control device results in at least a portion of the pressurized fluid of the fluid circuit bypassing the fan, thereby reducing the speed of the fan while increasing a pressure magnitude of and increasing a temperature of the fluid system. 
         [0007]    The present invention further relates to a method for heating a work vehicle including providing a pressurized fluid circuit having a pump and a fan for cooling pressurized fluid of the fluid circuit. Pressurized fluid of the fluid circuit provided to the fan results in fan operation. A speed of the fan corresponds to a flow rate of pressurized fluid of the fluid circuit provided to the fan. A control device is in fluid communication with the fluid circuit, the control device operable between a first position and a second position. The first position of the control device results in substantially all of the pressurized fluid of the fluid circuit being provided to the fan. The second position of the control device results in at least a portion of the pressurized fluid of the fluid circuit bypassing the fan, thereby reducing the speed of the fan while increasing a pressure magnitude of and increasing a temperature of the fluid system. The method further includes selectably actuating the control device between the first position and the second position. 
         [0008]    An advantage of the present invention is the capability to rapidly warm hydraulic oil in a hydraulic circuit. 
         [0009]    A further advantage of the present invention is the capability to rapidly warm hydraulic oil in a hydraulic circuit independent of or without resulting in external movement of an implement or requiring continuous input from an operator. 
         [0010]    It is to be understood that an embodiment of the present invention may incorporate one or more of the identified advantages. 
         [0011]    Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIGS. 1 and 2  are schematic representations of an exemplary embodiment of a fluid heating system of the present disclosure. 
       
    
    
       [0013]    Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring to the drawings,  FIGS. 1-2  show schematic representations of an exemplary embodiment of the present disclosure.  FIG. 1  shows a fluid heating system  10  including a control device  12 , such as a digitally controlled solenoid valve having a first position  20  and a second position  22 . Control device  12  is controlled by a control module  24  that receives input signals from sensors  34  associated with temperatures and/or other component/system/subsystem operating parameters. Under normal operating conditions, such as when the ambient temperature is greater than a predetermined minimum temperature, such as 90° C. in one application, and in combination with other parameters in other applications such as discussed in further detail below, hydraulic pump  26  provides pressurized hydraulic oil to a fluid circuit  28 . In response to sensors  34  controlled by control module  24  sensing the temperature of the hydraulic oil in fluid circuit  28 , as well as other temperature/parameters as discussed in further detail below, control device  12  is maintained in first position  20 , providing unobstructed flow to and from fan motor  14 . 
         [0015]    However under operating conditions in which hydraulic oil is less than a predetermined minimal temperature, such as zero (0)° C. in one operating condition, and in combination with other parameters and other operating conditions such as disclosed in further detail below, a motor hydraulic pump  26  provides pressurized hydraulic oil to fluid circuit  28 . In response to sensors  34  controlled by electronic control module  24 , the temperature of the hydraulic oil and fluid circuit  28 , as well as other exemplary temperature/parameters that are below predetermined minimum values as discussed in further detail below, control device  12  is actuated to second position  22 . As shown in the figures, second position  22  of control device  12  contains a flow restrictor therein for raising the fluid pressure between pump  26  and control device  12 . When the fluid pressure of the hydraulic oil is sufficiently raised, a valve such as a pressure relief or bypass valve  30  is urged to an open position, permitting the pressurized oil to bypass fan motor  14  such as shown by directional arrows  36 , continue through the remainder of fluid circuit  28  through to oil sump  32 . As a result, the pressurized oil bypassing fan motor  14 , only a small amount of hydraulic oil reaches fan motor  14 , so that fan motor  14  operates at a reduced rotational speed, thereby reducing cooling capacity of hydraulic oil contained in fluid circuit  28  by fan  16 , while forcing flow of hydraulic oil of fluid circuit  28  to bypass the majority of the system flow at an elevated pressure back to oil sump  32 . The combination of flow of the hydraulic oil at increased pressure, as well as the reduced cooling capacity of fan  16  more quickly results in raising the fluid temperature of the hydraulic oil. In other words, the arrangement of the control device  12  reduces the amount of time required to reach a nominal hydraulic oil operating temperature, while requiring no continuous interaction from the operator, such as initial operator interaction of an optional manually operated control  42 . In one embodiment, fluid heating system  10  operates substantially independent of or substantially without input from an operator. In another embodiment, operation of fluid heating system  10  may be automatic, i.e., not requiring interaction from the operator. 
         [0016]    As shown in the figures, fluid circuit  28  includes one of component module  38  or component module  40 , depending upon which of component modules  38 ,  40  is purchased by the user. The component modules  38 ,  40  which are not otherwise relevant to operation of the present disclosure are not further discussed. 
         [0017]    An optional heat exchanger  44  may be utilized by fluid circuit  28 , such as for purposes of thermal exchange with other system(s) and/or subsystem(s) such as discussed in more detail below. The location of exchanger  44  may be utilized anywhere downstream of the node  46  of component module  40 , or downstream of the node  48  of component module  38 , depending on which of component modules  38 ,  40  is present in fluid system  28 . 
         [0018]    It is to be understood that the size of the restriction of control device  12  and second position  22  may be optimized to generate a specific heat load. In one embodiment, control device  12  may have multiple positions with differently sized restrictions. In one embodiment, the restriction of control device  12  may be variably sized. 
         [0019]    It was found in development that this solution could also solve an additional problem discovered on working vehicles, such as diesel burning wheel loaders with Selective Catalytic Reduction (SCR) exhaust treatment. On some of these vehicles, the engine must be periodically warmed above a certain temperature when idling for extended periods of time, such as more than six hours, to prevent damage to the vehicle. The system  10  described above can be used to increase the temperature of the diesel engine (and in turn the SCR system) by creating a parasitic load on the engine in the manner previously described. By energizing or actuating control device  12  to second position  22 , it was shown that the temperature of the diesel engine could be elevated above this threshold temperature automatically, again independent of or without any input from the operator. This arrangement has an additional advantage of substantially eliminating external motion such as might be associated might when loading the engine via the ground drive or implement hydraulic cylinders. Substantially eliminating such external motion of the work vehicle reduces danger and risk to objects and personnel near the work vehicle while permitting a process that can be automatically performed. It is to be understood that the system  10  would be operated at predetermined time intervals less than those resulting in damage to the vehicle. 
         [0020]    Control device  12  operation can also be utilized to warm a frozen urea tank (not shown) more quickly, reducing the time to operation of the work vehicle in cold temperatures, the urea used as a reductant within the SCR system. 
         [0021]    There are at least four different uses of the fluid heating system of the present disclosure:
       1. Heating the air temperature inside the cab more quickly   2. Periodically elevating the engine temperature to combat hydrocarbon build-up in SCR system   3. More rapidly warming the urea tank   4. More rapidly warming the hydraulic oil.       
 
         [0026]    In one embodiment, feedback signals received from various sensors provided to the control module may include the following operating parameters: 
       Ambient Temperature 
     Coolant Temperature 
     Transmission Oil Temperature 
     Hydraulic Oil Temperature 
     Urea Temperature 
     Engine Speed 
       [0027]    Fan Reverser state
 
Auto Fan state
 
However, in other embodiments, other combinations of feedback signals, possibly including additional parameters may be utilized, such as air cabin temperature.
 
         [0028]    One embodiment relates to heating the air temperature inside the operator cab more quickly. For example, to turn ON the feature (i.e., energize the control valve or control device  12 ) all of the following conditions must be met for a predetermined period of time, such as 20 consecutive seconds, although in other embodiments other time periods of different duration and/or different parameters may be used: 
       Ambient Temperature&lt;0° C. 
     Coolant Temperature&lt;75° C. 
     Transmission Oil Temperature&lt;75° C. 
     Hydraulic Oil Temperature&lt;75° C. 
     Engine Speed&gt;650 RPM 
       [0029]    Fan Reverser state=Not Active 
       Auto Fan=ON 
       [0030]    In this embodiment, once the valve or control device  12  is energized (ON), auto fan control is be disabled and fan speed should be set to maximum fan speed. 
         [0031]    In this embodiment, once the valve or control device  12  is energized, any of the following conditions may be used to turn the valve OFF, although in other embodiments, the number and amount of conditions may be different: 
       Charge Air Temperature&gt;90° C. 
     Coolant Temperature&gt;85° C. 
     Transmission Oil Temperature&gt;90° C. 
     Hydraulic Oil Temperature&gt;90° C. 
     Engine Speed&lt;600 RPM 
     Fan Reverser=Active 
       [0032]    In this embodiment, if any parameter for entry or exit condition of this routine is not present or out of range, then the feature is disabled. 
         [0033]    In one embodiment, to periodically elevate the engine temperature to combat hydrocarbon build-up in the SCR system: 
         [0034]    To turn ON the feature (i.e., energized the valve or control device  12 ) the following conditions are to be met for X1 consecutive seconds:
       Coolant Temperature&lt;Y1° C.
 
Once the valve or control device  12  is energized, auto fan control is to be disabled and fan speed is to be set to maximum fan speed.
 
Once the valve or control device  12  is energized, the following conditions may be used to turn the valve OFF:
   Temperature&gt;YY1° C. for Z1 consecutive seconds (YY1≧Y1)
 
If the Coolant Temperature signal is not present or out of range, then the feature is to be disabled.
       
 
         [0037]    In one embodiment, to more rapidly warm the urea tank: 
         [0000]    To turn ON the feature (i.e., energize the valve or control device  12 ) the following conditions are to be met for X2 consecutive seconds:
       Urea Temperature&lt;Y2° C.
 
Once the valve or control device  12  is energized, auto fan control is to be disabled and fan speed set to maximum fan speed.
 
Once the valve or control device  12  is energized, the following conditions may be used to turn the valve OFF:
   Urea Temperature&gt;YY2° C. for Z2 consecutive seconds (YY2≧Y2)
 
If the: Urea Temperature signal is not present or out of range, then the feature is to be disabled.
       
 
         [0040]    In one embodiment, to more rapidly warm the hydraulic oil: 
         [0000]    To turn ON the feature (i.e., energize the valve or control device  12 ) the following conditions are to be met for X3 consecutive seconds:
       Hydraulic Oil Temperature&lt;Y3° C.
 
Once the valve or control device  12  is energized, auto fan control is to be disabled and fan speed set to maximum fan speed.
 
Once the valve or control device  12  is energized, the following conditions are to turn the valve OFF:
   Hydraulic Oil Temperature&gt;YY3° C. for Z3 consecutive seconds (YY3≧Y3)
 
If the: temperature signal is not present or out of range, then the feature is to be disabled.
       
 
         [0043]    While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.