Coolant pump for internal combustion engine

Abstract

An internal combustion engine relies on a liquid coolant to dissipate heat that is produced by combustion within the engine. A coolant pump, which is driven by the engine itself, circulates the coolant through passageways in the engine. The pump includes a clutch such as a magnetic particle clutch or a magnetorheological clutch, that relies on a magnetic field to control the speed at which the pump operates and the rate that it circulates the coolant, so that a variable speed ratio exists between the speed of the engine and the speed of the pump.

1 . A coolant pump for an internal combustion engine, said pump comprising: 
 a housing;    an impeller including vanes located in the housing;    a rotary drive member; and    a magnetic clutch interposed between the rotary drive member and the impeller, the clutch including a first clutch element that rotates with the impeller and a second clutch element that rotates with the drive member, an electromagnet that produces a magnetic field, and a substance through which torque is transferred between the first and second clutch elements, the substance being responsive to the magnetic field produced by the electromagnet such that the velocity of the first clutch element relative to the second clutch element depends on the strength of the magnetic field, whereby the speed at which the impeller rotates is independent of the speed at which the drive member rotates and is controlled by the clutch.    
   
   
       2 . A coolant pump according to  claim 1  wherein the first and second clutch elements, the impeller, and the drive member rotate about a common axis.  
   
   
       3 . A coolant pump according to  claim 1  wherein the clutch is a magnetic particle clutch.  
   
   
       4 . A coolant pump according  claim 3  wherein the first clutch element has a peripheral surface that is presented away from the axis; wherein the second clutch element has an interior surface that is presented toward the axis and toward the peripheral surface of the first clutch element; there being a gap that exists between the peripheral surface of the first element and the interior surface of the second element; and wherein the substance through which torque is transferred is magnetic particles that are in the gap.  
   
   
       5 . A coolant pump according to  claim 4  wherein the peripheral surface of the first element and the interior surface of the second element are cylindrical and parallel.  
   
   
       6 . A coolant pump according to  claim 3  wherein the electromagnet is carried by one of the clutch elements; and further comprising a connector for connecting the electromagnet with an electrical energy source that remains stationary while clutch elements rotate.  
   
   
       7 . A coolant pump according to  claim 6  wherein the connector includes slip rings and brushes that contact the slip rings.  
   
   
       8 . A coolant pump according to  claim 1  wherein the clutch is a magnetorheological clutch and the substance through which torque is transferred is a magnetorheological fluid.  
   
   
       9 . In combination with an internal combustion engine containing coolant passageways and a coolant within the passageways for dissipating heat produced by combustion within the engine; a coolant pump for circulating the coolant through the passageways within the engine, said pump comprising: 
 an impeller exposed to the coolant and including a shaft that rotates about an axis;    a rotary drive member coupled to and driven by the engine at a speed which correlates to the speed of the engine; and    a clutch interposed between the drive member and the impeller, the clutch including an electromagnet and containing a substance through which torque is transferred from the drive member to the impeller, with the substance being responsive to the magnetic field produced by the electromagnet.    
   
   
       10 . The combination according to  claim 9  wherein the clutch comprises a first clutch element attached to the impeller for rotation with the impeller at the speed of the impeller; and 
 a second clutch element attached to the drive member for rotation with the drive member at the speed of the drive member, there being a gap between the first and second clutch elements, and wherein the substance through which torque is transferred is magnetic particles in the gap between the first and second clutch members, all such that the speed of the impeller is dependent on the strength of the magnetic field.    
   
   
       11 . The combination according to  claim 10  and further comprising a primary heat exchanger connected to the engine; and wherein the pump also circulates the coolant through the primary heat exchanger.  
   
   
       12 . The combination according to  claim 11  and further comprising a secondary heat exchanger connected to the engine; and wherein the pump also circulates the coolant through the secondary heat exchanger.  
   
   
       13 . The combination according to  claim 12  wherein the primary heat exchanger is a radiator through which air passes to extract heat from the coolant; and wherein the secondary heat exchanger is a heater that includes a valve for controlling the rate at which coolant flows through it.  
   
   
       14 . The combination according to  claim 13  wherein the engine has a crankshaft and a pulley carried by the crankshaft, wherein the drive member of the pump is a pulley, and further comprising a belt that passes over the pulleys.  
   
   
       15 . The combination according to  claim 9  wherein the substance through which torque is transferred in the clutch is a magnetorheological fluid.  
   
   
       16 . A method of dissipating heat from an internal combustion engine having coolant passageways containing a liquid coolant, a shaft from which power is delivered and a pump impeller located in one of the coolant passageways for circulating the coolant through the passageways, said method comprising: 
 interposing between the shaft of the engine and the impeller of the pump a clutch having a first element that rotates with the impeller at a fixed speed ratio, a second element that rotates with the shaft at a fixed speed ratio; an electromagnet, and a torque-transfer substance located between the clutch elements for transferring torque from the second element to the first element, the substance being responsive to the magnetic field produced by the electromagnet such that the speed of the first clutch element relative to the second clutch element depends on the magnitude of the magnetic field; and    varying the magnetic field produced by the electromagnet to control the speed of the impeller and the circulation of coolant through the coolant passageways.