Method of flowing coolant through exhaust heat recovery system after engine shutoff
First Claim
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1. A method, comprising:
- cooling a rear axle heat exchanger (RAHX) at a rear axle of a vehicle by flowing a coolant, comprising water and maintained separate from an engine coolant, through a coolant system while an engine is not operating, while adjusting a flow rate of the coolant through the RAHX in response to a rear axle oil temperature of rear axle oil exchanged between only the RAHX and the rear axle via first and second oil lines, the coolant and the rear axle oil maintained separate from each other within the RAHX without mixing, by, responsive to a first condition, concurrently adjusting a first three-way valve and a second three-way valve to control a flow of coolant from the first three-way valve to a thermal storage vessel (TSV) and to control a flow of coolant from the second three-way valve to the RAHX, where the first three-way valve is adjustable to bypass the flow of coolant around the TSV to the second three-way valve, and where the second three-way valve is adjustable to bypass the flow of coolant around the RAHX to a coolant line coupled to an outlet of the RAHX, and, responsive to a second condition, adjusting only one of the first three-way valve or the second three-way valve.
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Abstract
Methods and systems are provided for adjusting a flow of coolant through a coolant system including a rear axle heat exchanger. In one example, a method may include flowing coolant through the coolant system while an engine is not operating. In another example, a method may include increasing a flow of coolant to the rear axle heat exchanger while the engine is not operating when a rear axle oil temperature exceeds a threshold temperature.
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Citations
20 Claims
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1. A method, comprising:
cooling a rear axle heat exchanger (RAHX) at a rear axle of a vehicle by flowing a coolant, comprising water and maintained separate from an engine coolant, through a coolant system while an engine is not operating, while adjusting a flow rate of the coolant through the RAHX in response to a rear axle oil temperature of rear axle oil exchanged between only the RAHX and the rear axle via first and second oil lines, the coolant and the rear axle oil maintained separate from each other within the RAHX without mixing, by, responsive to a first condition, concurrently adjusting a first three-way valve and a second three-way valve to control a flow of coolant from the first three-way valve to a thermal storage vessel (TSV) and to control a flow of coolant from the second three-way valve to the RAHX, where the first three-way valve is adjustable to bypass the flow of coolant around the TSV to the second three-way valve, and where the second three-way valve is adjustable to bypass the flow of coolant around the RAHX to a coolant line coupled to an outlet of the RAHX, and, responsive to a second condition, adjusting only one of the first three-way valve or the second three-way valve. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for a coolant system of a vehicle, comprising:
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in response to vehicle engine shutoff, flowing a coolant, comprising water and maintained separate from a vehicle engine coolant, through coolant lines fluidly coupling an exhaust gas heat exchanger (EGHX) to each of a rear axle heat exchanger (RAHX) at a rear axle of the vehicle and a thermal storage vessel (TSV); cooling the RAHX by adjusting a flow rate of the coolant from the EGHX through the RAHX in response to a rear axle oil temperature of rear axle oil exchanged directly between the RAHX and the rear axle via first and second oil lines, the coolant and the rear axle oil maintained separate from each other within the RAHX without mixing, and, responsive to a first condition, concurrently adjusting a first three-way valve and a second three-way valve to control a flow of coolant from the first three-way valve to the TSV and to control a flow of coolant from the second three-way valve to the RAHX, where the first three-way valve is adjustable to bypass the flow of coolant around the TSV to the second three-way valve, and where the second three-way valve is adjustable to bypass the flow of coolant around the RAHX to a coolant line coupled to an outlet of the RAHX, and, responsive to a second condition, adjusting only one of the first three-way valve or the second three-way valve; and heating the TSV by adjusting a flow rate of the coolant from the EGHX through the TSV in response to a temperature of the TSV. - View Dependent Claims (11, 12, 13, 14)
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15. A method for a rear axle coolant system of an engine, comprising:
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during engine operation; responsive to a first condition, recovering exhaust gas heat at an exhaust gas heat exchanger (EGHX) via a coolant comprising water in a coolant loop maintained separate from an engine coolant and storing the recovered exhaust gas heat in a thermal storage vessel (TSV); and responsive to a second condition, transferring heat from the TSV to rear axle lubrication oil via a rear axle heat exchanger (RAHX) at a rear axle, the rear axle lubrication oil maintained separate from the coolant and exchanged directly between the RAHX and the rear axle via first and second oil lines; and during engine non-operation; responsive to a third condition, concurrently adjusting a first three-way valve and a second three-way valve to control a flow of coolant from the first three-way valve to the TSV and to control a flow of coolant from the second three-way valve to the RAHX, where the first three-way valve is adjustable to bypass the flow of coolant around the TSV to the second three-way valve, and where the second three-way valve is adjustable to bypass the flow of coolant around the RAHX to a coolant line coupled to an outlet of the RAHX; responsive to a fourth condition, adjusting only one of the first three-way valve or the second three-way valve; responsive to a temperature of the rear axle lubrication oil, adjusting a flow of the coolant from the EGHX to the RAHX; responsive to a temperature of the TSV, adjusting a flow of the coolant from the EGHX to the TSV; and responsive to a temperature of the EGHX, adjusting a flow rate of the coolant through the coolant loop. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification