Vehicle and control method for vehicle

Abstract

To provide a technique capable of successfully thawing urea water in an SCR device even when frequency of use of an engine during traveling is relatively low.SOLUTION: A vehicle S100 includes: an engine 10; a motor 21; a battery 23; an SCR device 30; a cooling system 40 that cools the battery 23 or the motor 21 by supplying a coolant to the battery 23 or the motor 21; and a control device 50. The cooling system 40 has: a pump 45; a first flow passage 41; a second flow passage 42; and a valve 46 that switches between a state where the coolant flows in the first flow passage 41 and a state where the coolant flows in the first flow passage 41 and the second flow passage 42. When a temperature of urea water is a first threshold value or lower, the control device 50 controls a state of the valve 46 to the state where the coolant flows in the first flow passage 41 and the second flow passage 42 so as to supply the coolant to a urea water tank 31.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle and a method for controlling a vehicle. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a selective catalytic reduction (SCR) system using an SCR device has been known as an exhaust gas purification system for purifying NOx in exhaust gas from a diesel engine.

[0003] The SCR system supplies urea water into exhaust gas. Ammonia is generated by the heat of the exhaust gas, and this ammonia reduces NOx on the SCR catalyst, thereby purifying the exhaust gas. Urea water freezes at approximately -11°C. Therefore, there is a risk that SCR devices may not function properly in cold regions. As a countermeasure, a technology is known in which a cooling line for circulating engine coolant is passed through the urea tank, and the urea water is thawed by heat exchange between this coolant and the urea water (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-013060 A Summary of the Invention [Problem to be solved by the invention]

[0005] When engine coolant is used to thaw the urea water as in the conventional technology, a problem occurs in that, for example in a plug-in hybrid vehicle, the engine is used infrequently and the temperature of the engine coolant is insufficient to thaw the urea water.

[0006] Therefore, an object of the present invention is to provide a technique that can satisfactorily thaw the urea water in an SCR device even when the frequency of engine use during driving is relatively low. [Means for solving the problem]

[0007] A vehicle of one embodiment of the present invention includes an engine, a motor, a battery that stores electricity to be supplied to the motor, an SCR device that sprays urea water into exhaust gas to purify the exhaust gas discharged from the engine, a cooling system that cools the battery or the motor by supplying a coolant to the battery or the motor, and a control device that controls the operation of the cooling system, wherein the cooling system has a first flow path through which the coolant flows and which exchanges heat between the coolant and the motor or the battery, a second flow path through which the coolant flows and which exchanges heat between the coolant and the urea water, and a valve that switches between a state in which the coolant flows through the first flow path and a state in which the coolant flows through the first flow path and both the first and second flow paths, and when the temperature of the urea water is below a first threshold value, the control device controls the state of the valve to a state in which the coolant flows through the first and second flow paths so that the coolant is supplied to a urea water tank.

[0008] When a temperature of the urea water is higher than a first threshold value, the control device may control a state of the valve so that the coolant flows through the first flow path and does not flow through the second flow path.

[0009] The control device may operate a pump to pump the coolant in a thawing mode in which a first amount of the coolant per unit time is pumped when the temperature of the urea water is equal to or lower than a first threshold, and operate the pump in an anti-freeze mode in which a second amount of the coolant, the discharge amount of which is less than the first amount, is pumped when the temperature of the urea water exceeds the first threshold and is equal to or lower than a second threshold that is greater than the first threshold.

[0010] When the temperature of the urea water is higher than a second threshold value, the control device may control a state of the valve so that the coolant flows through the first flow path and does not flow through the second flow path.

[0011] The control device may, when in a motor drive mode in which the motor is operated using power from the battery to run the vehicle, when the remaining charge of the battery is below a threshold and the temperature of the urea water is below the first threshold, switch the state of the valve to a state in which the coolant flows through the first flow path and the second flow path so that the coolant is supplied to the urea water tank.

[0012] The vehicle according to one aspect of the present invention may further include an inverter for supplying electric power to the motor, and the cooling system may also supply the coolant to the inverter.

[0013] One embodiment of the present invention provides a method for controlling a vehicle including an engine, a motor, a battery that stores electricity to be supplied to the motor, an SCR device that sprays urea water into exhaust gas to purify the exhaust gas discharged from the engine, and a cooling system that cools the battery or the motor by supplying a coolant to the battery or the motor, wherein the cooling system has a first flow path through which the coolant flows and which exchanges heat between the coolant and the motor or the battery, a second flow path through which the coolant flows and which exchanges heat between the coolant and the urea water, and a valve that switches between a state in which the coolant flows through the first flow path and a state in which the coolant flows through the first flow path and both the first and second flow paths, and the method includes a step in which a control device controls the state of the valve to a state in which the coolant flows through the first and second flow paths so that the coolant is supplied to a urea water tank when the temperature of the urea water is below a first threshold value. Effect of the Invention

[0014] According to the present invention, it is possible to provide a technique that can satisfactorily thaw the urea water in an SCR device even when the engine is used relatively infrequently during driving. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a vehicle. [Diagram 2]6 is a flowchart showing an operation for thawing urea water. [Diagram 3] 10 is a flowchart showing an operation for switching between a thawing mode and a freeze prevention mode. [Figure 4] 6 is a flowchart showing an operation for defrosting the urea water in preparation for an engine drive mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] FIG. 1 is a diagram showing a schematic configuration of a vehicle S100. In FIG. 1, solid arrows indicate the flow of coolant flowing through a first flow path, and dashed arrows indicate the flow of coolant flowing through a second flow path. The vehicle S100 is, for example, a plug-in hybrid vehicle having an engine and a motor as a power source. The vehicle S100 is, for example, a large vehicle such as a truck.

[0017] The vehicle S100 includes, as main components, an engine 10, a motor 21, an inverter 22, a battery 23, an SCR device 30, a cooling system 40, and a control device 50.

[0018] One of the features of the vehicle S100 is that the urea water in the SCR device 30 is thawed not with engine coolant but with coolant for cooling the motor 21, inverter 22, and battery 23. With this configuration, even when the engine 10 is used infrequently and the temperature of the engine coolant is not sufficient, the urea water can be satisfactorily thawed by the coolant whose temperature has been raised by cooling the motor 21, etc.

[0019] The engine 10 is, for example, a diesel engine. The engine 10 burns a mixture of fuel and intake air in a cylinder to generate driving force. The engine 10 rotates a crankshaft, which is a rotating shaft, by the driving force. The driving force of the engine 10 is transmitted to a propeller shaft via an automatic transmission mechanism. The rotation of the propeller shaft rotates a pair of wheels, and the vehicle S100 moves forward or backward.

[0020] The motor 21 operates as an electric motor or a generator depending on the running state of the vehicle S100. The motor 21 generates a driving force that rotates a propeller shaft. The driving force of the motor 21 is transmitted to the propeller shaft, and the pair of wheels rotate in response to the rotation of the propeller shaft in the same manner as described above.

[0021] The battery 23 is, for example, a lithium ion battery. The battery 23 stores power to be supplied to the motor 21. When the motor 21 operates as a generator, the battery 23 is charged with power generated by the motor 21 (specifically, regenerative power generated by converting kinetic energy into electrical energy). The battery 23 may be charged with power from an external commercial power source. The battery 23 supplies the pump 45 with power for operating the pump 45.

[0022] The battery 23 is provided with a remaining battery capacity sensor 71 that measures the remaining battery capacity. The remaining battery capacity sensor 71 measures, for example, the state of charge (SOC) of the battery 23. The remaining battery capacity sensor 71 outputs the measured remaining battery capacity to the control device 50.

[0023] The inverter 22 converts DC power to AC power and AC power to DC power. When the motor 21 operates as an electric motor, the inverter 22 converts the DC power of the battery 23 into AC power and supplies the power to the motor 21. When the motor 21 operates as a generator, the inverter 22 converts the AC power generated by the motor 21 into DC power and supplies the power to the battery 23.

[0024] The SCR device 30 is a purification device having an SCR (Selective Catalytic Reduction) having a selective reduction catalyst as a catalyst for purifying exhaust gas. The SCR device 30 has a urea water tank 31 and a spray unit 32.

[0025] The urea water tank 31 is a tank for storing urea water. The urea water tank 31 is provided with a temperature sensor 72. The temperature sensor 72 measures the temperature of the urea water stored in the urea water tank 31. The temperature sensor 72 outputs the measured temperature to the control device 50.

[0026] The spray unit 32 is connected to the urea water tank 31. The spray unit 32 sprays the urea water from the urea water tank 31 to the exhaust gas passing through the exhaust pipe 11 at a position upstream of the selective reduction catalyst in order to purify the exhaust gas from the engine 10.

[0027] (Cooling System 40) The cooling system 40 cools at least one of the motor 21, the inverter 22, and the battery 23 by supplying a coolant to these components. In the example of Fig. 1, the cooling system 40 cools all of the motor 21, the inverter 22, and the battery 23. The cooling system 40 has a first flow path 41, a second flow path 42, a pump 45, and a valve 46.

[0028] The first flow path 41 is a circulation flow path that flows the coolant pumped from the pump 45 toward the battery 23, the inverter 22, and the motor 21. In the battery 23, the inverter 22, and the motor 21, heat is exchanged between the heat generated in each component and the coolant flowing through the first flow path 41, thereby cooling the battery 23, the inverter 22, and the motor 21. The first flow path 41 that has passed through the motor 21 is connected to the upstream side of the pump 45. In FIG. 1, the first flow path 41 between the valve 46 and the pump 45 is shown as a flow path 41a. Note that the order in which the coolant is supplied is not limited to the order of the battery 23, the inverter 22, and the motor 21, and can be changed as appropriate.

[0029] The second flow path 42 is a flow path that flows the coolant toward the urea water tank 31. The coolant that has passed through the motor 21 and the like and has been heated to a temperature sufficient to thaw the frozen urea water is supplied to the urea water tank 31, thereby thawing the urea water. In this embodiment, the second flow path 42 is provided so as to branch off from the middle of the first flow path 41 to form a second circulation flow path. An end of the second flow path 42 is connected to the upstream side of the pump 45.

[0030] The pump 45 pumps the coolant. The operation of the pump 45 is controlled by the control device 50. In this embodiment, the pump 45 pumps a first amount of coolant per unit time in response to a control signal from the control device 50. This operation mode is referred to as a thawing mode in this specification. In the thawing mode, the amount of coolant discharged per unit time is greater than in the anti-freezing mode described below, so that the urea water can be thawed in a shorter time. In addition, the pump 45 pumps the coolant at a second amount, which is less than the first amount of coolant discharged per unit time. This operation mode is referred to as an anti-freezing mode.

[0031] The valve 46 is, for example, an electromagnetic valve. The valve 46 switches the communication state of the flow paths between a state in which the cooling liquid flows through the flow path 41a of the first flow path 41 and returns to the pump 45, and a state in which the cooling liquid flows through the second flow path 42 and returns to the pump 45. The operation of the valve 46 is controlled by the control device 50.

[0032] (Control device 50) The control device 50 has a processor and a storage unit, and controls the operation of each part of the vehicle S100. The storage unit includes a storage device such as a memory, a hard disk, or an SSD (Solid State Drive). The storage unit stores a computer program. The processor executes the computer program stored in the storage unit to realize the functions of the control device 50, which will be described later.

[0033] The control device 50 acquires the remaining amount of the battery 23 output by the remaining amount sensor 71. The control device 50 acquires the temperature of the urea water output by the temperature sensor 72.

[0034] (Thawing urea solution) In cold regions, the urea water in the SCR device 30 of the vehicle S100 may freeze. When the vehicle S100 switches its driving mode from a motor drive mode in which the vehicle runs using the driving force of the motor 21 to an engine drive mode in which the vehicle runs using the driving force of the engine 10, if the urea water is frozen, the SCR device 30 does not function normally and is unable to purify the exhaust gas. Therefore, the control device 50 controls the pump 45 and the valve 46 as follows.

[0035] 2 is a flowchart showing an operation for thawing the urea water. In step S1, the control device 50 controls the inverter 22 to run the vehicle S100 in the motor drive mode. In this state, the control device 50 controls the pump 45 and the valve 46 to flow the coolant through the first flow path 41 to cool the battery 23, the inverter 22, and the motor 21.

[0036] Next, in step S2, the control device 50 obtains the temperature of the urea water from the temperature sensor 72 and determines whether the temperature of the urea water is equal to or lower than a first threshold value. The first threshold value is, for example, the freezing temperature of the urea water. If the answer is No in step S2, the series of operations ends. As an example, if the temperature of the urea water is higher than the first threshold value (No in step S2), the control device 50 may control the state of the valve 46 to a state in which the coolant flows through the first flow path 41 and does not flow through the second flow path 42. Here, when the control device controls the valve 46 to a certain state, it means that the valve 46 is set to a certain state.

[0037] If the temperature of the urea water is equal to or lower than the first threshold value (Yes in step S2), in step S3, the control device 50 switches the state of the valve 46 so that the coolant is supplied to the urea water tank 31. Specifically, the control device 50 switches the state of the valve 46 so that the coolant flows through the second flow path 42. As a result, the coolant whose temperature has been increased by heat exchange with the battery 23, the inverter 22, and the motor 21 is supplied to the urea water tank 31, and the urea water is thawed.

[0038] Next, in step S4, the control device 50 obtains the temperature of the urea water from the temperature sensor 72, and determines whether or not the temperature of the urea water exceeds the end threshold value set as the temperature at which the urea water is thawed. If the result in step S4 is No, the control device 50 repeats step S4. If the result in step S4 is Yes, in step S5, the control device 50 switches the state of the valve 46 to stop the supply of the cooling liquid to the urea water tank 31.

[0039] Through the above series of operations, the cooling liquid is supplied to the urea water tank 31, and the frozen urea water can be thawed.

[0040] (Switching between thawing mode and freeze prevention mode) In the vehicle S100, it is assumed that the urea water in the urea water tank 31 may be frozen or may possibly freeze. When the urea water is frozen, it is preferable to supply the coolant in the thawing mode so that the urea water can be thawed quickly, and when there is a possibility that the urea water may freeze, it is preferable to supply the coolant in the anti-freeze mode so that the urea water does not freeze. Therefore, the control device 50 controls the pump 45 and the valve 46 as follows.

[0041] Fig. 3 is a flowchart showing the operation for switching between the thawing mode and the antifreeze mode. In step S11, similar to step S1 in the flowchart of Fig. 2, the control device 50 controls the inverter 22 to run the vehicle S100 in the motor drive mode.

[0042] Next, in step S12, the control device 50 obtains the temperature of the urea water from the temperature sensor 72, and determines whether the temperature of the urea water is equal to or lower than a first threshold value. This step is the same as step S2 in the flowchart of FIG.

[0043] If the answer is Yes in step S12, in step S13, the control device 50 controls the pump 45 and the valve 46 so that in the thawing mode, the coolant is supplied to the urea water tank 31. In the thawing mode, the pump 45 pumps out, for example, a first amount of coolant whose discharge amount per unit time is greater than the second amount in the freeze prevention mode.

[0044] If the answer is No in step S12, in step S14, the control device 50 determines whether the temperature of the urea solution is equal to or lower than a second threshold value. The second threshold value is a value set as a temperature at which the urea solution may freeze, and is, for example, a value greater than the first threshold value. If the answer is No in step S14, the series of operations ends. As an example, when the temperature of the urea solution is higher than the second threshold value (No in S14), the control device 50 may control the state of the valve 46 to a state in which the coolant flows through the first flow path 41 and does not flow through the second flow path 42.

[0045] If the answer is Yes in step S14, in step S15, the control device 50 controls the pump 45 and the valve 46 so that in the anti-freeze mode, the coolant is supplied to the urea water tank 31. In the anti-freeze mode, the pump 45 pumps out a second amount of the coolant, the amount of which is smaller than the first amount per unit time.

[0046] In step S16, similarly to step S4 in the flowchart of Fig. 2, the control device 50 determines whether or not the temperature of the urea water has exceeded a predetermined end threshold. If the result in step S16 is No, step S16 is repeated. If the result in step S16 is Yes, in step S17, the control device 50 stops the pump 45 and switches the state of the valve 46 to stop the supply of coolant to the urea water tank 31.

[0047] By the series of operations described above, the cooling liquid is supplied in the thawing mode or the anti-freezing mode to thaw the urea water or prevent the urea water from freezing. According to such operation control, the amount of cooling water supplied to the urea water tank 31 to prevent freezing can be reduced, so that the output of the pump 45 can be reduced.

[0048] (Defrosting urea solution in preparation for engine drive mode) In a plug-in hybrid vehicle, when the battery 23 has a sufficient remaining charge, the vehicle S100 is driven in the motor drive mode, and when the remaining charge of the battery 23 becomes low, the drive mode is switched to the engine drive mode. When the engine drive mode is started in this manner, if the urea water is frozen, the SCR device 30 cannot operate normally. Therefore, the control device 50 controls the pump 45 and the valve 46 as follows.

[0049] Fig. 4 is a flowchart showing an operation for defrosting the urea water in preparation for the engine drive mode. In step S21, similar to step S1 in the flowchart of Fig. 2, the control device 50 controls the inverter 22 to run the vehicle S100 in the motor drive mode.

[0050] Next, in step S22, the control device 50 judges whether the remaining charge of the battery 23 is equal to or less than a threshold value. This threshold value is, for example, a value obtained by adding a predetermined margin value to a value set as the remaining charge of the battery 23 at which the driving mode should be changed from the motor drive mode to the engine drive mode. If the result in step S22 is No, the series of operations ends.

[0051] If the result of step S22 is Yes, then in step S23, the control device 50 obtains the temperature of the urea water from the temperature sensor 72 and determines whether the temperature of the urea water is equal to or lower than the first threshold value. This step is the same as step S2 in the flowchart of FIG.

[0052] Steps S24, S25, and S26 are the same as steps S3, S4, and S5 in the flowchart of FIG. 2, respectively, and therefore will not be described here.

[0053] By performing the above series of operations, when the remaining charge of the battery 23 decreases and the mode is switched to the engine drive mode, the urea water can be thawed in advance, so that the SCR device can effectively purify the exhaust gas after the mode is switched to the engine drive mode.

[0054] (Effects of vehicle S100) As described above, according to the configuration of this embodiment, when the temperature of the urea water is equal to or lower than a predetermined threshold value (e.g., the freezing temperature of the urea water), the coolant that has passed through the motor and the like and has been heated is supplied to the urea water tank 31, so that the frozen urea water can be thawed. The vehicle S100 of this embodiment is not configured to thaw the urea water using the cooling water of the engine 10, so that the urea water can be thawed satisfactorily regardless of the frequency of use of the engine 10.

[0055] (Modification) Before controlling the valve 46 to supply coolant to the urea water tank 31, the control device 50 may obtain the temperature of the coolant flowing through the first flow path 41 from a specified temperature sensor, and if the temperature is below a threshold value set as a temperature sufficient to thaw frozen urea water, circulate the coolant through the first flow path 41 until the coolant exceeds the threshold value, and then switch the state of the valve 46 to supply the coolant to the urea water tank 31.

[0056] In the above embodiment, the cooling liquid that has passed through the valve 46 flows through the flow path 41a or through the second flow path 42, but the present invention is not limited to this. For example, the cooling liquid that has passed through the valve 46 may flow through both the flow path 41a and the second flow path 42. In this case, the valve 46 may be capable of changing the ratio of the flow rate flowing into the flow path 41a and the flow rate flowing into the second flow path 42 to an arbitrary ratio. The control device 50 can change this ratio of the valve 46 to more precisely control the amount of cooling liquid flowing through each flow path.

[0057] The control device 50 may have a table that associates one or more parameters such as the driving conditions of the vehicle S100, the time, the driving characteristics of the driver, and the remaining battery charge with the timing when the engine drive mode is used, or may have a learned model that outputs the timing when the engine drive mode is used when one or more parameters such as the driving conditions of the vehicle S100, the time, the driving characteristics of the driver, and the remaining battery charge are input, and may determine the timing when the engine drive mode is used using the above table or the learned model based on the acquired parameters of the vehicle S100, and may perform thawing of the urea water as described above prior to that timing.

[0058] After the transition to the engine drive mode is made, a cooling line (not shown) for circulating cooling water for cooling the engine provided in the urea tank may be used to exchange heat between the cooling water and the urea water to suppress a drop in temperature or freezing of the urea water.

[0059] While one embodiment of the present invention has been described above, this specification also discloses an invention of a computer program executed by a processor and an invention of a vehicle control method.

[0060] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination combines the effect of the original embodiment. [Explanation of symbols]

[0061] 10 Engine 11 Exhaust pipe 21 Motor 22 Inverter 23 Battery 30 SCR device 31 Urea tank 32 Spray section 40 Cooling System 41 First Channel 41a Flow path 42 Second Flow Stream 45 Pump 46 Valve 50 Control device 71 Remaining amount sensor 72 Temperature Sensor S100 vehicle

Claims

1. The engine, A motor; a battery for storing power to be supplied to the motor; an SCR device that sprays urea water into exhaust gas to purify the exhaust gas discharged from the engine; a cooling system that cools the battery or the motor by supplying a coolant to the battery or the motor; A control device for controlling an operation of the cooling system; Equipped with The cooling system comprises: a first flow path through which the coolant flows and through which heat is exchanged between the coolant and the motor or the battery; a second flow path through which the cooling liquid flows and through which heat is exchanged between the cooling liquid and the urea water; a valve that switches between a state in which the cooling liquid flows through the first flow path and a state in which the cooling liquid flows through the first flow path and the second flow path; having When a temperature of the urea water is equal to or lower than a first threshold value, the control device controls a state of the valve to a state in which the cooling liquid flows through the first flow path and the second flow path so that the cooling liquid is supplied to the urea water tank. vehicle.

2. When a temperature of the urea water is higher than a first threshold value, the control device controls a state of the valve so that the coolant flows through the first flow path and does not flow through the second flow path.

2. The vehicle of claim 1.

3. The control device includes: operating a pump that pumps the coolant in a thawing mode in which a first amount of the coolant is pumped per unit time when the temperature of the urea water is equal to or lower than a first threshold value; When the temperature of the urea water exceeds the first threshold value and is equal to or lower than a second threshold value that is greater than the first threshold value, the pump is operated in an anti-freeze mode in which a second amount of the coolant is pumped, the second amount being smaller than the first amount per unit time.

2. The vehicle of claim 1.

4. When the temperature of the urea water is higher than a second threshold value, the control device controls a state of the valve so that the coolant flows through the first flow path and does not flow through the second flow path.

4. The vehicle according to claim 3.

5. The control device includes: when the remaining charge of the battery is equal to or lower than a threshold value and the temperature of the urea water is equal to or lower than the first threshold value in a motor drive mode in which the motor is operated by power from the battery to run the vehicle, the state of the valve is switched to a state in which the coolant flows through the first flow path and the second flow path so that the coolant is supplied to the urea water tank.

2. The vehicle of claim 1.

6. further comprising an inverter for supplying power to the motor; The cooling system also supplies the cooling liquid to the inverter.

2. The vehicle of claim 1.

7. The engine, A motor; a battery for storing power to be supplied to the motor; an SCR device that sprays urea water into exhaust gas to purify the exhaust gas discharged from the engine; a cooling system that cools the battery or the motor by supplying a coolant to the battery or the motor; Equipped with The cooling system comprises: a first flow path through which the coolant flows and through which heat is exchanged between the coolant and the motor or the battery; a second flow path through which the cooling liquid flows and through which heat is exchanged between the cooling liquid and the urea water; a valve that switches between a state in which the cooling liquid flows through the first flow path and a state in which the cooling liquid flows through the first flow path and the second flow path; A method for controlling a vehicle having a control device controlling a state of the valve to a state in which the cooling liquid flows through the first flow path and the second flow path so that the cooling liquid is supplied to the urea water tank when a temperature of the urea water is equal to or lower than a first threshold value; How to control a vehicle.

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