Controller for hybrid vehicle

Abstract

To provide a controller for a hybrid vehicle which suppresses an occurrence of dilution of engine oil by warming up an engine when it is estimated that dilution of the engine oil is going to occur.SOLUTION: A controller for a hybrid vehicle includes: an air-conditioning system 16 which circulates in an engine 20 a heating medium to be used for air-conditioning in a cabin and warms up the engine 20; an estimating part 14 which estimates an occurrence of dilution in engine oil to be lubricating oil of the engine 20; and a control part 12 controlling the air-conditioning system 16. The control part 12 performs control to drive a heater 22 of the air-conditioning system 16 and warms up the engine 20 when the estimating part 14 estimates that the dilution in engine oil is going to occur, and to finish driving the heater 22 when the heating medium reaches a prescribed temperature or higher.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] In vehicles, engine oil dilution can occur, where water or gasoline fuel gets mixed into the engine oil, diluting the engine oil. For example, when the temperature of the cooling water circulating in the vehicle's air conditioning system is low, gasoline can easily get into the oil pan from the combustion chamber through the gap between the cylinder and the piston, diluting the engine oil. Also, for example, in hybrid vehicles, when the engine is running for a short time, the temperature of the engine does not rise, so water vapor generated by engine combustion may not be discharged into the exhaust system. As a result, condensation on the walls of the combustion chamber increases, and this condensation, i.e., water, can get into the oil pan from the combustion chamber, diluting the engine oil.

[0003] When engine oil is diluted, its lubricating performance is reduced, so techniques for dealing with the occurrence of engine oil dilution have been proposed. For example, a control device for a hybrid vehicle disclosed in Patent Document 1 controls the engine oil to increase its temperature when the engine oil reaches a predetermined diluted state. This control raises the engine oil temperature to a temperature at which water evaporates, so that the engine oil can be restored from the diluted state. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-168379 A Summary of the Invention [Problem to be solved by the invention]

[0005] By the way, as a countermeasure against the occurrence of engine oil dilution, there is a method of quickly recovering from the dilution state and suppressing an increase in the amount of dilution of the engine oil with water or fuel, but it is more preferable to be able to suppress the occurrence of the dilution itself, because by suppressing the occurrence of engine oil dilution, it is possible to avoid a decrease in the output of the internal combustion engine and a deterioration in fuel efficiency caused by a decrease in the lubricating performance of the engine oil.

[0006] Therefore, this specification provides a control device for a hybrid vehicle that, when it is predicted that engine oil dilution will occur, warms up the engine to suppress the occurrence of engine oil dilution. [Means for solving the problem]

[0007] The control device for a hybrid vehicle disclosed in this specification is a control device for a hybrid vehicle, and includes an air conditioning system that circulates a heat medium used for air conditioning in the vehicle cabin through an engine to warm up the engine, an estimation unit that estimates the occurrence of dilution in engine oil, which is a lubricating oil for the engine, and a control unit that controls the air conditioning system, wherein the control unit is characterized in that when the estimation unit estimates the occurrence of dilution of the engine oil, it operates a heater in the air conditioning system to warm up the engine, and when the heat medium reaches or exceeds a predetermined temperature, it controls the operation of the heater to be terminated. Effect of the Invention

[0008] According to the control device for a hybrid vehicle disclosed in this specification, by predicting the occurrence of engine oil dilution, the engine can be warmed up and the temperature of the engine oil can be increased before the dilution occurs, thereby suppressing the occurrence of engine oil dilution. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating a schematic configuration of a control device for a hybrid vehicle. [Diagram 2] 4 is a flowchart showing an example of processing in a control device for a hybrid vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a control device for a hybrid vehicle will be described with reference to the drawings.

[0011] FIG. 1 is a diagram showing a schematic configuration of a control device for a hybrid vehicle. As shown in FIG. 1, a control device 10 for a hybrid vehicle includes a control unit 12, an estimation unit 14, an air conditioning system 16, and a battery warm-up system 18. The control unit 12 is an electronic control unit having at least a CPU for performing various arithmetic processing and a memory in which control programs and data are stored. The control unit 12 controls the air conditioning of the hybrid vehicle in which the control device 10 is mounted. Specifically, the control unit 12 receives information measured by each sensor described later and controls each device to be controlled by executing a program. The control unit 12 further includes an estimation unit 14, which estimates the occurrence of dilution of engine oil, which is a lubricating oil for the engine 20. The estimation method performed by the estimation unit 14 is not particularly limited, and for example, in this example, the estimation is performed based on the temperature of water, which is a heat medium circulating in the air conditioning system 16.

[0012] The air conditioning system 16 is a circuit through which a heat medium (i.e., water in this example) used for air conditioning circulates to heat the vehicle interior, and circulates the water through the engine 20 to warm up the engine 20. As shown in FIG. 1, the air conditioning system 16 includes the engine 20, a heater 22, a flow control valve 24, a water pump 26, a heater core 28, and a heat exchanger 30.

[0013] The engine 20 and the heater 22 are heat sources for heating the vehicle interior. In general, in a hybrid vehicle, a driving mode in which the power from the engine is used as the driving force of the vehicle (hereinafter, appropriately referred to as "HV driving") and a driving mode in which the engine is stopped and only the power of the electric motor is used as the driving force of the vehicle (hereinafter, appropriately referred to as "EV driving") are selectively applied. In the control device 10 of the hybrid vehicle in this example, the waste heat of the engine 20 is used as a heat source in HV driving, and the heater 22 is used as a heat source in EV driving, except when special control is required as described later. Here, when the engine 20 is started at a low temperature and when the engine temperature is low thereafter while driving, the engine 20 must be warmed up. In this case, the heater 22 is used as a heat source. The control unit 12 controls the flow adjustment valve 24 to control which of the engine 20 and the heater 22 is used as the heat source to operate the air conditioning system 16. In addition to switching the heat source in the air conditioning system 16, the flow control valve 24 also adjusts the amount of water flowing in.

[0014] The water pump 26 is a pump for circulating water in the direction of the arrow in the air conditioning system 16. The heater core 28 is composed of tubes and fins (both not shown), and functions as a heat dissipation device in the air conditioning system 16 because the coolant for the engine 20 flows through the tubes and heat is exchanged. The heat exchanger 30 is provided between the air conditioning system 16 and the battery warm-up system 18, and is a device for exchanging thermal energy between the water circulating through the air conditioning system 16 and the water circulating through the battery warm-up system 18.

[0015] 1, the air conditioning system 16 further includes water temperature sensors 32, 34. The water temperature sensor 32 is a sensor for measuring the temperature of water after passing through the heater 22. The water temperature sensor 34 is a sensor for measuring the temperature of water after passing through the engine 20. Information measured by each of the water temperature sensors 32, 34 is transmitted to the control unit 12. As described above, the control unit 12 in this example estimates the occurrence of engine oil dilution based on the information from the water temperature sensors 32, 34.

[0016] The battery warm-up system 18 is a circuit in which water circulates as a heat medium for cooling or heating the battery, and includes a heat exchanger 30, a battery 36, a water pump 38, and a water temperature sensor 40. The battery 36 is a secondary battery that can be discharged and charged. The battery 36 stores electric power supplied from outside the hybrid vehicle and electric power regenerated from the kinetic energy of the vehicle, and supplies electric power used for driving the vehicle. The water pump 38 is a pump for circulating water in the direction of the arrow in the battery warm-up system 18. The water temperature sensor 40 is a sensor for measuring the temperature of water after passing through the battery 36. Information measured by the water temperature sensor 40 is transmitted to the control unit 12. The information is used by the control unit 12 to determine whether or not the temperature of the battery 36 needs to be adjusted. Since the performance of the battery 36 decreases at low temperatures, the battery 36 is heated at the start of the vehicle and during subsequent driving at low temperatures to raise the temperature of the battery 36 to a predetermined value.

[0017] Next, the control of the air conditioning system 16 performed by the control unit 12 will be described with reference to FIG. 2. FIG. 2 is a flowchart showing an example of processing in a control device for a hybrid vehicle. First, the engine 20 is operated during HV running (S10). Even when the engine 20 is operated, the temperature of the engine 20 may not increase because the engine 20 is frequently operated and stopped for short periods in a hybrid vehicle. In such a case, dilution of the engine oil may occur, so the control unit 12 controls the estimation unit 14 to estimate the occurrence of dilution of the engine oil (S12). As an example, the estimation unit 14 estimates whether or not dilution of the engine oil has occurred based on the temperature of the water measured by the water temperature sensor 34. When the estimation unit 14 estimates the occurrence of dilution of the engine oil (Yes in S12), the control unit 12 operates the heater 22 to promote warming up of the engine 20 even when the engine 20 is operating (S14). On the other hand, if the estimation unit 14 does not estimate the occurrence of engine oil dilution (No in S12), the control unit 12 does not perform any particular control (S16).

[0018] Next, after operating the heater 22, the control unit 12 determines whether or not the difference between the water temperature in the air conditioning system 16 and the target water temperature exceeds a predetermined value (S18). When the difference between the water temperature in the air conditioning system 16 and the target water temperature exceeds the predetermined value, the water temperature in the air conditioning system 16 is high (i.e., in some cases, the water temperature is excessively high) (Yes in S18). Therefore, in such a case, the control unit 12 controls the high-temperature water to be circulated to the battery warm-up system 18 via the heat exchanger 30. That is, the control unit 12 passes water through the circuit of the battery warm-up system 18 (S20). This control suppresses the rise in the water temperature in the air conditioning system 16 and suppresses excessive heat radiation from the heater core 28. On the other hand, when the difference between the water temperature in the air conditioning system 16 and the target water temperature is equal to or less than the predetermined value (No in S18), the control unit 12 controls the water to continue circulating in the circuit of the air conditioning system 16 (S22).

[0019] Next, the control unit 12 determines whether or not the water temperature in the engine 20 exceeds a predetermined value, even in a state in which water is being passed through the circuit of the battery warm-up system 18 and high-temperature water is being supplied to the battery 36 (S24). If the water temperature in the engine 20 is equal to or lower than the predetermined value (No in S24), the control unit 12 shifts the process to S14 since accelerated warm-up of the engine 20 is still necessary. On the other hand, if the water temperature in the engine 20 exceeds the predetermined value (Yes in S24), the control unit 12 ends the series of controls since accelerated warm-up of the engine 20 is not in a state in which engine oil dilution may occur (S26).

[0020] The above description is merely an example, and the control device for a hybrid vehicle disclosed in this specification may be configured to operate a heater in the air conditioning system to warm up the engine when the estimation unit estimates that engine oil dilution will occur, and to control the operation of the heater to end when the heat medium reaches a predetermined temperature or higher. For example, in the flowchart shown in Fig. 2, the estimation performed by the estimation unit 14 is based on the temperature of the water circulating in the air conditioning system 16, but is not limited to this. A known technique (for example, JP 2004-316471 A) may be used as a method for estimating whether engine oil dilution will occur. [Explanation of symbols]

[0021] 10 Hybrid vehicle control device, 12 control unit, 14 estimation unit, 16 air conditioning system, 18 battery warm-up system, 20 engine, 22 heater.

Claims

[Claim 1] A control device for a hybrid vehicle, an air conditioning system that circulates a heat medium used for air conditioning the vehicle interior through the engine to warm up the engine; An estimation unit that estimates the occurrence of dilution in engine oil, which is a lubricating oil for the engine; A control unit that controls the air conditioning system; Equipped with The control unit is When the estimation unit estimates that the engine oil is diluted, the engine is warmed up by operating a heater in the air conditioning system; When the heat medium reaches a predetermined temperature or higher, the operation of the heater is controlled to be terminated. A control device for a hybrid vehicle.

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