Engine cooling system

Abstract

A cooling system for an internal combustion engine is disclosed in which the supply of coolant to a cylinder block 6 is controlled independently of the coolant supply to a cylinder head 10 so that the temperatures of the cylinder block 6 and the cylinder head 10 can be optimised to produce improved performance and economy.

1 . A cooling system for an internal combustion engine comprising a cooling circuit including passages formed in a cylinder head of the engine and in a cylinder block of the engine and at least one conduit connecting the passages in the cylinder head and cylinder block to an inlet to a pump used to circulate the coolant through the cooling circuit wherein the pump is a variable flow rate pump controlled by an electronic control unit, the coolant passages in the cylinder block are connected by a first coolant supply conduit to an outlet from the pump, the coolant passages in the cylinder head are connected by a second coolant supply conduit to an outlet from the pump, the flow through at least one of the first and second coolant supply passages is controlled by an electronically controlled flow control valve operably connected to an electronic controller used to control the opening and closing of the electronically controlled flow control valve and the flow through the other of the first and second coolant supply passages has a predetermined flow restriction to prevent unlimited flow therethrough.  
   
   
       2 . A cooling system as claimed in  1  wherein the predetermined flow restriction is formed by one of an orifice and the use of a coolant supply passage having a relatively small cross-sectional flow area representing a restriction to flow for at least a portion of the length of the other coolant supply passage.  
   
   
       3 . A cooling system as claimed in  claim 1  or in  claim 2  wherein the electronic control unit is formed as part of the electronic controller used to control opening and closing of the first electronically controlled flow control valve.  
   
   
       4 . A cooling system as claimed in any of  claims 1  to  3  wherein the cooling system further comprises at least one temperature sensor operably connected to the electronic controller to sense the temperature of a part of the cylinder head and to supply a signal indicative of the sensed temperature to the electronic controller, at least one temperature sensor operably connected to the electronic controller to sense the temperature of a part of the cylinder block and to supply a signal indicative of the sensed temperature to the electronic controller, the electronic controller is operable, at least during normal engine running, to control the opening and closing of the electronically controlled flow control valve based upon at least one of the signals received from the cylinder head and cylinder block temperature sensors and the electronic control unit is operable, at least during normal engine running, to control the flow rate from the variable flow rate pump based upon at least one of the signals received from the cylinder head and cylinder block temperature sensors.  
   
   
       5 . A cooling system as claimed in  claim 4  wherein, during normal engine running, the flow from the variable flow rate pump is controlled to provide the minimum required flow based upon at least one of the signals received from the cylinder head and cylinder block temperature sensors.  
   
   
       6 . A cooling system as claimed in  claim 4  or in  claim 5  wherein the cooling system further comprises at least one coolant temperature sensor operably connected to the electronic controller for sensing the temperature of the coolant exiting the cylinder head and the electronic controller is operable to control the opening and closing of the electronically controlled flow control valve based upon the signals received from at least one of the cylinder head and cylinder block temperature sensors and from the coolant temperature sensor.  
   
   
       7 . A cooling system as claimed in  claim 4  in  claim 5  wherein the cooling system further comprises at least one coolant temperature sensor operably connected to the electronic controller for sensing the temperature of the coolant exiting at least one of the cylinder block and the cylinder head and the electronic control unit is operable to control the flow from the variable flow rate pump based upon the signals received from at least one of the cylinder head and cylinder block temperature sensors and from the coolant temperature sensor.  
   
   
       8 . A cooling system as claimed in any of  claims 1  to  7  wherein the electronically controlled flow control valve controls the flow of coolant through the first coolant supply conduit to the cylinder block, at least one cylinder head temperature sensor is operably connected to the electronic controller to sense the temperature of a part of the cylinder head and to supply a signal indicative of the sensed temperature to the electronic controller and the temperature of the cylinder head is controlled by the electronic control unit, at least during normal engine running, by varying the flow from the variable flow rate pump to maintain the temperature as sensed by the or each cylinder head sensor within a predetermined desired range based upon the sensed temperature of the cylinder head and at least one cylinder block temperature sensor is operably connected to the electronic controller to sense the temperature of a part of the cylinder block and to supply a signal indicative of the sensed temperature to the electronic controller and the temperature of the cylinder block is controlled, at least during normal engine running, by the electronic controller opening and closing the electronically controlled flow control valve to maintain the temperature of the cylinder block within a predetermined desired temperature range based upon the sensed temperature of the cylinder block.  
   
   
       9 . A cooling system as claimed in any of  claims 1  to  7  wherein the electronically controlled flow control valve controls the flow of coolant through the second coolant supply conduit to the cylinder head, at least one cylinder head temperature sensor is operably connected to the electronic controller to sense the temperature of a part of the cylinder head and to supply a signal indicative of the sensed temperature to the electronic controller and the temperature of the cylinder head is controlled, at least during normal engine running, by the electronic controller opening and closing the electronically controlled flow control valve to maintain the temperature of the cylinder head within a predetermined desired temperature range based upon the sensed temperature of the cylinder head and at least one cylinder block temperature sensor is operably connected to the electronic controller to sense the temperature of a part of the cylinder block and to supply a signal indicative of the sensed temperature to the electronic controller and the temperature of the cylinder block is controlled by the electronic control unit, at least during normal engine running, by varying the flow from the variable flow rate pump to maintain the temperature as sensed by the or each cylinder block sensor within a predetermined desired range based upon the sensed temperature of the cylinder block.  
   
   
       10 . A method for cooling an internal combustion engine having a cylinder head, a cylinder block, a first coolant supply conduit to supply coolant from a an electronically controlled variable flow rate pump to passages formed in the cylinder block, a second coolant supply conduit for independently supplying coolant from the pump to passages formed in the cylinder head, an electronically controlled flow control valve to control the flow of coolant though one of the first and second coolant supply conduits, a predetermined flow restriction to prevent unlimited flow through the other of the first and second coolant supply conduits wherein the method comprises opening and closing the or each electronically controlled flow control valve and changing the flow rate from the variable flow rate pump to maintain, at least during normal engine running, the temperature of the cylinder block within a desired temperature range and the temperature of the cylinder head within a desired temperature range.  
   
   
       11 . A method as claimed in  claim 10  wherein at least one temperature sensor is provided to sense the temperature of a part of the cylinder head and at least one temperature sensor is provided to sense the temperature of a part of the cylinder block and the method further comprises opening an closing the or each electronically controlled flow control valve and varying the flow rate from the pump based upon the signals received from cylinder head and cylinder block temperature sensors.  
   
   
       12 . A cooling system substantially as described herein with reference to the accompanying drawing.  
   
   
       13 . A method for cooling an internal combustion engine substantially as described herein with reference to the accompanying drawing.