Patent Grant
8944017
The present teachings generally include a cooling system for a vehicle powertrain.
In a vehicle powertrain, operating temperatures of an engine and a transmission are typically managed in part by a cooling system that has circulating coolant. An engine heat exchanger establishes thermal communication between engine oil and the coolant. A transmission heat exchanger establishes thermal communication between transmission fluid and the coolant. Coolant flow to the heat exchangers is typically via the same route whether in a cooling mode or in a heating mode. The heat exchangers must be sized to sufficiently perform the cooling and heating tasks.
A cooling system for a vehicle powertrain is provided that controls the source of coolant flow to the heat exchangers using one or more valves. This enables relatively warmer coolant to be used for fluid heating, and relatively cooler coolant to be used for cooling. The heat exchangers can more efficiently perform the separate heating and cooling tasks when the coolant flow source is selected in this manner, potentially reducing friction losses and increasing fuel economy. Additionally, because the heat exchangers are more efficient, they may be a relatively smaller size than if the same coolant flow route was used for both heating and cooling, thereby realizing the fuel economy benefits associated with a decrease in overall weight.
Specifically, a cooling system is provided for a powertrain that has an engine and a transmission driven by the engine. The cooling system has an engine heat exchanger in thermal communication with engine oil in the engine. A transmission heat exchanger is in thermal communication with transmission oil in the transmission. A pump has a pump inlet and a pump outlet. The pump pumps coolant through a plurality of coolant flow passages. A valve assembly is in fluid communication with the pump outlet and has a first and a second position that at least partially establish different coolant flow modes through the coolant flow passages.
The valve assembly has a first inlet that receives coolant that flows from the pump outlet, to an engine inlet, then through the engine to an engine outlet. The valve assembly also has a second inlet that receives coolant that flows from the pump outlet and bypasses the engine. The valve assembly has only a single outlet that directs coolant flow to at least one of the engine heat exchanger and the transmission heat exchanger, and then back to the pump inlet. The first position of the valve assembly fluidly connects the first inlet to the single outlet and blocks the second inlet to establish a first of the coolant flow modes. The second position of the valve assembly fluidly connects the second inlet to the single outlet and blocks the first inlet to establish a second of the coolant flow modes.
Because coolant flowing to the first inlet flows through the engine, and coolant flowing to the second inlet bypasses the engine, a heating mode is established when the valve assembly is in the first position, and a cooling mode is established when the valve assembly is in the second position. The valve assembly is operable to move from the first position to the second position in response to a first predetermined operating condition. For example, the first predetermined operating condition may be a predetermined coolant temperature at which the system switches from a heating mode to a cooling mode.
In one aspect of the present teachings, the valve assembly is a first valve assembly that controls coolant flow to the engine heat exchanger, and a second valve assembly configured to function in a similar manner controls coolant flow to the transmission heat exchanger. A second predetermined operating condition different than the first predetermined operating condition can cause the second valve assembly to be moved to the second position. In this manner, the conditions under which the engine heat exchanger is changed from a heating mode to a cooling mode can be different than the conditions under which the transmission heat exchanger is changed from a heating mode to a cooling mode. Heating and cooling of the engine and the transmission can thus be separately optimized.
The position of the valve assembly can be controlled by a controller and an actuator. Alternatively, the valve assembly can be a mechanical valve assembly that self-actuates, such as a valve assembly that has a wax motor thermostat at one inlet that is actuated by the coolant at a predetermined temperature, and a ball valve at the other inlet.
The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description of the best modes for carrying out the present teachings when taken in connection with the accompanying drawings.
Referring to the drawings, wherein like components are referred to with identical reference numbers throughout the several views,
The powertrain 10 has a cooling system 20 with a plurality of coolant flow passages A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, and R containing coolant that is moved through the passages via a pump 21. Specifically, when the pump 21 is powered, coolant is pumped from passage Q to a pump inlet 23, through the pump 21 to a pump outlet 25, and then to passage A. The pump 21 can be driven by the engine 12, or can be separately powered. The route of the coolant through the remaining passages is dependent upon the position of valve assemblies 50, 60, and an engine thermostat valve 34 as discussed herein.
The cooling system 20 is configured to warm or cool the engine 12 and the transmission 18 as appropriate for varying vehicle operating conditions, as described herein. The cooling system 20 includes an engine heat exchanger 22 that cools or heats engine oil contained in the engine 12 via heat exchange between the engine oil and the coolant. The engine oil can be routed between an engine sump 24 and the heat exchanger 22 via engine oil passages 24A, 24B. Alternatively, the engine oil can be routed from a passage in the engine block 14 to the heat exchanger 22, or from another portion of the engine 12. Coolant flows through the heat exchanger 22 from passage K to passage O.
The cooling system 20 further includes a transmission heat exchanger 26 that cools or heats transmission oil contained in the transmission 18 via heat exchange between the transmission oil and the coolant. The transmission oil routes between the transmission 18 and the heat exchanger 26 via transmission oil passages 18A, 18B, and coolant flows through the heat exchanger 26 from passage M to passage N.
The cooling system 20 includes a radiator 28 with a coolant inlet 30 and a coolant outlet 32. The radiator 28 is configured to cause convective cooling of the coolant as air rushes over conduits (not shown) in the radiator 28 through which the coolant flows from the coolant inlet 30 to the coolant outlet 32. An engine thermostat valve 34 controls whether coolant flows through the radiator 28. In the closed position shown, the thermostat valve 34 prevents coolant flow from the radiator outlet 32 to the remainder of the cooling system 20. In an open position, a thermostat valve member 36 will open to allow flow from passage P to passage Q, thereby enabling flow from passage G, to the coolant input 30, through the radiator 28 to the coolant outlet 32, and to the passage P. The engine thermostat 34 can be configured to open when the coolant temperature flowing into the pump 21 reaches a predetermined temperature that indicates additional cooling is necessary.
The cooling system 20 has a passenger compartment heater 38 with a coolant inlet 40 and a coolant outlet 42. Coolant flowing through the heater 38 undergoes heat exchange with air in a vehicle passenger compartment to warm the air.
The cooling system 20 has a first valve assembly 50 that has a housing 51 that forms a first inlet 52, a second inlet 54, and a single outlet 56. The first valve 50 has an internal valve member 58 that is selectively moveable from a first position shown in solid, to a second position 58A shown in phantom. When the valve member 56 is in the first position, coolant can flow from the first inlet 52 to the single outlet 58 but cannot flow from the second inlet 54 to the single outlet 56. When the valve member 58 is in the second position 58A, coolant can flow from the second inlet 54 to the single outlet 56 but cannot flow from the first inlet 52 to the single outlet 56.
In the embodiment shown, the first valve assembly 50 is moved by an actuator A1 under the control of a controller C1. The controller C1 receives a sensor signal from a sensor (not shown) that indicates a first predetermined operating condition is occurring. The controller C1 then sends an activation signal or other activating input to the actuator A1 to cause the actuator A1 to move the valve member 58 from the first position to the second position 58A. The controller C1 and actuator A1 can utilize electric, pneumatic, hydraulic, or electro-mechanical control of the valve member 58.
The cooling system 20 has a second valve assembly 60 that has a housing 61 that forms inlet 62, inlet 64, and a single outlet 66. The inlet 62 can be referred to as a first inlet and the inlet 64 can be referred to as a second inlet, or, to differentiate from the inlets 50, 54 of valve assembly 50, can be referred to as a third inlet, and a fourth inlet, respectively. The first valve assembly 60 has an internal valve member 68 that is selectively moveable from a first position shown in solid, to a second position 68A shown in phantom. To differentiate from the first valve assembly 50, the first position of the valve member 68 can be referred to as a third position, and the second position 68A of the valve member 68 can be referred to as a fourth position. When the valve member 68 is in the first position, coolant can flow from the first inlet 62 to the single outlet 66 but cannot flow from the second inlet 64 to the single outlet 66. When the valve member 68 is in the second position 68A, coolant can flow from the second inlet 64 to the single outlet 66 but cannot flow through the first inlet 62.
In the embodiment shown, the second valve assembly 60 is moved by an actuator A2 under the control of a controller C1. The controller C1 receives a sensor signal from a sensor (not shown) that indicates a second predetermined operating condition is occurring. The controller C1 then sends an activation signal or other activating input to the actuator A2 to cause the actuator A2 to move the valve member 68 from the first position to the second position 68A. The controller C1 and actuator A1 can utilize electric, pneumatic, hydraulic, or electro-mechanical control of the valve member 68.
When the first valve assembly 50 is in the first position (i.e., valve member 58 is in the first position), a first coolant flow mode through the cooling system 20 results, with the coolant flowing through a first route. The first route includes coolant flow from the pump outlet 25, through passages A, B, C, D, E, F, and J to the first inlet 52. The passages C and D are internal cast passages in the engine bock 14 and the cylinder head 16, respectively. Coolant flows though passages C and D from an engine inlet 67 to an engine outlet 69. By routing the coolant through the engine block 14 and cylinder head 16, the coolant is warmed by the engine 12 prior to flowing through the engine heat exchanger 22.
Alternatively, if the first valve assembly 50 is in the second position 58A, a second coolant flow mode through the cooling system 20 results, with coolant flowing through a second route. The second route includes coolant flow from the pump outlet 25 through passages A, H, and I to the second inlet 54, bypassing the internal passages C and D in the engine 12. The coolant is thus not warmed by the engine 12 prior to flowing through the engine heat exchanger 22.
When the second valve assembly 60 is in the first position, another coolant flow mode through the cooling system 20 results, with the coolant flowing through a third route. This coolant flow mode can be referred to as a third coolant flow mode. The third route includes coolant flow from the pump outlet 25, through passages A, B, C, D, E, F, and J to the first inlet 62. By routing the coolant through the engine block 14 and cylinder head 16, the coolant is warmed by the engine 12 prior to flowing through the transmission heat exchanger 26.
Alternatively, if the second valve assembly 60 is in the second position 68A, a different coolant flow mode through the cooling system 20 results, with coolant flowing through still another route. This coolant flow mode can be referred to as a fourth coolant flow mode. Coolant will flow from the pump outlet 25 through passages A, H, and I to the second inlet 64, bypassing the internal passages C and D in the engine 12. The coolant is thus not warmed by the engine 12 prior to flowing through the heat exchanger 26.
A portion of the coolant in passage F will flow through the passenger compartment heater 38 and flow back to the pump 21 through passages L and R. Any coolant flowing through passage L, as well as coolant flowing through passage N after exiting the transmission heat exchanger 26, and coolant flowing through passage O after exiting the engine heat exchanger 22 converge at passage R and flow through the engine thermostat 34 back to the pump inlet 23. If the engine thermostat 34 is opened, a portion of the coolant flowing out of the engine 12 through passage E will be diverted through passage G, through the radiator 28 and back to the pump 21 through passages P and Q.
The controller C1 is configured to execute a stored algorithm that activates the actuators A1 and A2 in response to different predetermined operating conditions to ensure sufficient heating of the engine 12 and the transmission 18 by directing relatively warm coolant that has flowed through the engine 12 to one or both of the heat exchangers 22, 26 when operating conditions indicate that fluid heating is necessary. Maintaining the transmission fluid and the engine oil at a desirable temperature can reduce frictional losses caused by the drag of rotating components through unwarmed, relatively viscous, fluid or oil. Accordingly, the first valve assembly 50 remains in the first position until a first predetermined operating condition, such as a predetermined temperature of the coolant exiting the engine 12 at engine outlet 69 is attained, as determined by a temperature sensor (not shown). At that point, the controller C1 causes the actuator A1 to move the valve member 58 to the second position 58A, establishing a cooling mode in which relatively cool coolant will instead be directed to the engine heat exchanger 22 to help cool the engine oil, or maintain it within an ideal range.
Similarly, the controller C1 can maintain the second valve assembly 60 in the first position until transmission fluid temperature reaches a predetermined temperature, which can be the same or different that the engine oil temperature at which the first valve assembly 50 is moved. This predetermined temperature is referred to as the second predetermined operating condition. Once the transmission fluid temperature is reached, the controller C1 causes the actuator A2 to move the valve member 68 to the second position 68A, to begin cooling of the transmission fluid or maintaining it within an ideal range.
The movement of the valve assembly 50 from the first position to the second position, or the movement of the valve assembly 60 from the first position to the second position effectively allows the controller C1 to choose the coolant source by varying the route of the coolant entering the respective heat exchanger 22 or 26. By controlling the coolant source, the engine heat exchanger 22 and the transmission heat exchanger 26 can be of a reduced size in comparison to a cooling system in which only a single flow path for the coolant was available.
The controller C1 can be configured to activate the actuator A1 to move the valve member 58 back to the first position if operating conditions are such that the heating mode of the engine 12 should be resumed. Similarly, the controller C1 can be configured to activate the actuator A2 to move the valve member 68 back to the first position if operating conditions are such that the heating mode of the transmission 18 should be resumed.
The valve assembly 150 is a mechanical valve assembly that utilizes temperature of the coolant to establish the first or the second cooling flow mode. Accordingly, a controller and actuator are not required. Specifically, the valve assembly 150 includes a housing 151 that forms the first inlet 52, the second inlet 54, and the single outlet 56. A ball valve 158 is configured to be supported within the housing 151 to selectively block flow from the first inlet 52. A first wax motor thermostat 157 is positioned at the second inlet 54 and is configured to close the second inlet 54 when temperature of the coolant flowing from the pump outlet 25 and bypassing the engine 12 is below a first predetermined temperature. The first wax motor thermostat 157 is shown closing the second inlet 54 in
The ball valve 158 and housing 151 are configured so that the ball valve 158 unblocks the first inlet 52 when the first wax motor thermostat 157 blocks flow from the second inlet 54, and blocks the first inlet 52 when the first wax motor thermostat 157 unblocks flow from the second inlet 54. That is, the high pressure from the coolant entering at the second inlet 54 displaces the ball valve 158 to the position of
The valve assembly 150 has an optional second wax motor thermostat 161 positioned at the first inlet 52. The second wax motor thermostat 161 is shown in an open position in both
The coolant flowing from the second inlet 54 to the single outlet 56 in the cooling mode of
While the best modes for carrying out the many aspects of the present teachings have been described in detail, those familiar with the art to which these teachings relate will recognize various alternative aspects for practicing the present teachings that are within the scope of the appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3595262 | Fox et al. | Jul 1971 | A |
| 4319547 | Bierling | Mar 1982 | A |
| 7069880 | Hutchins | Jul 2006 | B2 |
| 20140000536 | Glassford | Jan 2014 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20140352636 A1 | Dec 2014 | US |
