Engine system with reversible fan

Abstract

An engine system includes an engine, a primary pump coupled to the engine, and a motor fluidly connected to the primary pump. The engine system further includes a heat exchanger fluidly connected to the engine, the heat exchanger configured to accept heated coolant from the engine and deliver cooled coolant to the engine. The engine system also includes a fan driven by the motor in either a forward or a reverse mode of operation, the fan configured to pull air toward the heat exchanger in a first direction during the forward mode of operation to assist in cooling the coolant, and to push air toward the heat exchanger in a second direction opposite the first direction during the reverse mode of operation. The engine system further includes a controller configured to operate the fan in the reverse mode of operation in response to a sensed temperature of the coolant and a speed of the fan in the forward mode of operation.

1 . An engine system, comprising:
 an engine;   a primary pump coupled to the engine;   a motor fluidly connected to the primary pump;   a heat exchanger fluidly connected to the engine, the heat exchanger configured to accept heated coolant from the engine and deliver cooled coolant to the engine;   a fan driven by the motor in either a forward or a reverse mode of operation, the fan configured to pull air toward the heat exchanger in a first direction during the forward mode of operation to assist in cooling the coolant, and to push air toward the heat exchanger in a second direction opposite the first direction during the reverse mode of operation; and   a controller configured to operate the fan in the reverse mode of operation in response to a sensed temperature of the coolant and a speed of the fan in the forward mode of operation.   
     
     
         2 . The engine system of  claim 1 , further comprising a coolant supply passage extending from the engine to the heat exchanger, and a coolant return passage extending from the heat exchanger to the engine, the heated coolant passing to the heat exchanger via the coolant supply passage and the cooled coolant passing to the engine via the coolant return passage. 
     
     
         3 . The engine system of  claim 1 , further comprising a supply passage delivering fluid to the motor from the primary pump, and a return passage delivering the fluid from the motor to the primary pump. 
     
     
         4 . The engine system of  claim 3 , further comprising a pressure resolver fluidly connected to both the supply passage and the return passage. 
     
     
         5 . The engine system of  claim 4 , wherein the pressure resolver comprises a pressure limiting valve configured to selectively reduce pressure of fluid directed to the primary pump to control displacement of the primary pump during the forward mode of operation. 
     
     
         6 . The engine system of  claim 5 , wherein the pressure resolver fluidly connects the pressure limiting valve to the supply passage during the forward mode of operation and fluidly connects the pressure limiting valve to the return passage during the reverse mode of operation. 
     
     
         7 . The engine system of  claim 5 , wherein the pressure resolver connects the one of the supply and the return passage having the higher pressure with the pressure limiting valve. 
     
     
         8 . The engine system of  claim 5 , wherein the pressure limiting valve moves from a flow-blocking position to a flow passing position when pressure of fluid passing through the resolver exceeds a pressure threshold. 
     
     
         9 . The engine system of  claim 5 , further comprising a displacement actuator fluidly connected to the pressure limiting valve, the displacement actuator operable to control displacement of the primary pump during the forward and reverse modes of operation. 
     
     
         10 . The engine system of  claim 9 , wherein the displacement actuator is operable to control the speed of the fan. 
     
     
         11 . A cleaning method for an engine system, comprising:
 passing coolant from an engine through a heat exchanger;   operating a fan in a forward direction pulling air toward the heat exchanger, the fan assisting in reducing a temperature of the coolant;   sensing an operating characteristic of the engine system;   operating the fan in a reverse direction, opposite the forward direction, in response to the sensed operating characteristic and a speed of the fan; and   resuming operation of the fan in the forward direction in response to the sensed operating characteristic satisfying a return criteria.   
     
     
         12 . The method of  claim 11 , wherein the operating characteristic comprises a temperature of the coolant. 
     
     
         13 . The method of  claim 12 , further comprising sensing the coolant temperature while the fan is operating in the reverse direction, comparing the coolant temperature sensed while the fan is operating in the reverse direction to a desired coolant temperature range, and resuming operation of the fan in the forward direction based on the comparison. 
     
     
         14 . The method of  claim 12 , further comprising sensing an increase in the coolant temperature while the fan is operating in the forward direction at a maximum cooling speed, and operating the fan in the reverse direction in response. 
     
     
         15 . The method of  claim 11 , wherein the operating characteristic comprises a pressure drop across the heat exchanger. 
     
     
         16 . The method of  claim 11 , further comprising increasing a rotational speed of the fan to a maximum cooling speed prior to operating the fan in the reverse direction. 
     
     
         17 . A cleaning method for an engine system, comprising:
 driving a primary pump with a combustion engine;   cooling the engine with coolant passing between the engine and a heat exchanger fluidly connected to the engine;   directing a pressurized flow of fluid from the primary pump to a fan motor;   generating a first flow of air in a first direction with a fan connected to the fan motor, the first flow of air passing through the heat exchanger to assist in reducing a temperature of the coolant;   increasing a speed of the fan;   sensing the temperature of the coolant while generating the first flow of air;   generating a second flow of air, in a second direction opposite the first direction, with the fan based on the speed of the fan and the coolant temperature sensed while generating the first flow of air;   sensing the temperature of the coolant while generating the second flow of air in the second direction;   determining that the coolant temperature sensed while generating the second flow of air is less than a coolant temperature threshold; and   generating a third flow of air in the first direction with the fan in response to the determination.   
     
     
         18 . The method of  claim 17 , wherein generating the second flow of air comprises reversing a direction of the pressurized flow of fluid. 
     
     
         19 . The method of  claim 17 , further comprising increasing the speed of the fan to a maximum cooling speed of the fan based on the coolant temperature sensed while generating the first flow of air. 
     
     
         20 . The method of  claim 17 , wherein generating the second flow of air comprises reversing a rotation direction of the fan.