Hybrid vehicle control device

Abstract

To provide a hybrid vehicle control device capable of controlling an abrupt temperature change in an inverter.SOLUTION: A control device for a hybrid vehicle, comprising an engine, a motor, an inverter which controls output of the motor, and a cooling water circulation passage which allows cooling water cooling the inverter to flow therethrough and performs heat exchange with an intake pipe of the engine, has: a water pump which can change a flow rate of the cooling water flowing through the cooling water circulation passage and a controller which controls the water pump. The controller is adapted to switch between first control to adjust the flow rate of the cooling water with the water pump to be less than a predetermined flow rate when the engine is stopped and second control to adjust the flow rate of the cooling water with the water pump to be equal to or larger than the predetermined flow rate when the engine is operated.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle equipped with an engine and a motor as driving power sources and an inverter for controlling the output of the motor, and more particularly to a control device for cooling the inverter. [Background technology]

[0002] Patent Document 1 describes a control device for a hybrid vehicle that is configured to lower the temperature of the coolant used to cool the inverter by dissipating heat from the coolant to intake air. This control device is configured to forcibly start the engine when the intake air temperature, estimated based on the inverter temperature and the outside air temperature, exceeds a predetermined temperature while the vehicle is running solely on motor power. That is, the control device is configured to start the engine to cause intake air to flow, and dissipate heat from the coolant to the intake air, thereby suppressing the temperature rise of the inverter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-209083 Summary of the Invention [Problem to be solved by the invention]

[0004] The control device described in Patent Document 1 forcibly starts the engine when the estimated intake air temperature reaches or exceeds a predetermined temperature during EV driving, which runs solely on motor power, thereby limiting the period and opportunities for EV driving and potentially reducing fuel economy. If the coolant flow rate is increased to prevent such forced engine starts, the inverter temperature will drop sharply when the vehicle switches from an engine-driven driving mode to an EV driving mode and the amount of heat transferred from the engine to the inverter decreases, which could result in a decrease in inverter durability due to the load caused by the sudden temperature change.

[0005] The present invention has been made in view of the above technical problems, and has an object to provide a control device for a hybrid vehicle that can suppress abrupt temperature changes in an inverter. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a vehicle comprising an engine and a motor as a driving force source, and an inverter for controlling the output of the motor. and are integrated into the engine room. A cooling water circulation system in which cooling water for cooling the inverter flows and exchanges heat with the intake pipe of the engine. The road The control device for a hybrid vehicle includes a water pump that can change the flow rate of the cooling water flowing through the cooling water circulation path, and a controller that controls the water pump, wherein the controller is configured to be able to switch between a first control that controls the flow rate of the cooling water from the water pump to less than a predetermined amount when the engine is stopped, and a second control that controls the flow rate of the cooling water from the water pump to more than the predetermined amount when the engine is running. [Effects of the Invention]

[0007] According to the present invention, when the engine is stopped, the flow rate of the coolant from the water pump is controlled to be less than a predetermined amount. Therefore, when the amount of heat absorbed by the inverter is small due to the engine being stopped, the inverter can be prevented from being rapidly cooled by the coolant. Conversely, when the engine is running, the flow rate of the coolant from the water pump is controlled to be greater than a predetermined amount. Therefore, when the amount of heat absorbed by the inverter is large due to the engine being running, the amount of heat dissipated by the coolant from the inverter can be increased, preventing the inverter from rapidly rising in temperature. In other words, by controlling the flow rate of the coolant from the water pump depending on whether the engine is running, the inverter can be appropriately cooled. Therefore, when the vehicle is traveling solely on motor power, the engine can be prevented from being forced to start in order to increase the amount of heat dissipated by the coolant, thereby preventing a deterioration in fuel economy. In addition, a decrease in the durability of the inverter due to a sudden change in inverter temperature can be prevented. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of an intake and exhaust system of an engine applied to a hybrid vehicle according to an embodiment of the present invention. [Figure 2] FIG. 4 is a diagram showing temperature changes of an inverter. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples of specific embodiments of the present invention and are not intended to limit the present invention.

[0010] A hybrid vehicle according to an embodiment of the present invention is a vehicle equipped with an engine and a motor as driving power sources, and specifically, is configured to be able to select an engine driving mode in which the vehicle runs solely on mechanical energy from the engine as an energy source, or on battery power in addition to mechanical energy from the engine, or an EV driving mode in which the engine is stopped and the vehicle runs solely on battery power as an energy source. That is, the hybrid vehicle according to an embodiment of the present invention includes a series hybrid vehicle, a parallel hybrid vehicle, and a series-parallel hybrid vehicle.

[0011] The engine can be configured in the same way as a conventional engine. That is, it is configured to generate power by burning a mixture of air and a fuel such as gasoline or diesel. FIG. 1 shows a schematic configuration of the intake and exhaust system of engine 1. Engine 1 shown in FIG. 1 is a water-cooled engine having four cylinders 2, each of which is connected to an intake manifold 3. An intake pipe 4 is connected to this intake manifold 3, and this intake pipe 4 is provided with a compressor 6 of a turbocharger 5 that operates using exhaust energy as a driving force source. A water-cooled intercooler (I / C) 7 is provided downstream of compressor 6 to cool the intake air that has been pressurized and heated by compressor 6.

[0012] 1, a bypass pipe 8 is provided to allow intake air to bypass the intercooler 7. That is, an upstream end of the bypass pipe 8 is connected to the intake pipe 4 on the upstream side of the intercooler 7, and a downstream end of the bypass pipe 8 is connected to the intake pipe 4 on the downstream side of the intercooler 7. A branch flow ratio change valve 9 is provided upstream of the bypass pipe 8 to control the amount of intake air flowing through the bypass pipe 8. The branch flow ratio change valve 9 is configured so that the ratio of the flow rate of intake air flowing through the bypass pipe 8 to the total flow rate flowing through the intake pipe 4 can be changed by controlling the opening degree of the branch flow ratio change valve 9.

[0013] An air cleaner 10 is disposed in the intake pipe 4 upstream of the compressor 6 to remove dust and dirt from the air flowing through the intake pipe 4, and an air flow meter 11 is disposed downstream of the air cleaner 10 to measure the flow rate of air flowing through the intake pipe 4, and a throttle valve 12 is disposed downstream of the air flow meter 11. Each cylinder 2 is provided with a fuel injection valve 13 that injects fuel.

[0014] An exhaust manifold 14 is also connected to each of the cylinders 2. An exhaust pipe 15 is connected to the exhaust manifold 14, and a turbine 16 of the turbocharger 5 is disposed in the exhaust pipe 15. An exhaust purification device 17 is provided in the exhaust pipe 15 downstream of the turbine 16 to purify unburned gases (carbon monoxide (CO) and hydrocarbons (HC)) and nitrogen oxides (NOx) contained in the exhaust and to capture particulate matter. The exhaust purification device 17 includes an oxidation catalyst (three-way catalyst) and a filter to capture PM.

[0015] An EGR pipe 18 is connected to a portion of the exhaust pipe 15 downstream of the exhaust purification device 17. This EGR pipe 18 is for recirculating a portion of the exhaust gas to the intake pipe 4, and therefore one end of the EGR pipe 18 is connected to the exhaust pipe 15, and the other end is connected to the intake pipe 4 upstream of the compressor 6. An EGR cooler 19 for cooling the recirculated exhaust gas is provided in the EGR pipe 18, and an EGR valve 20 for controlling the flow rate of the recirculated exhaust gas is provided on the intake pipe 4 side of the EGR cooler 19.

[0016] The motor can be configured in the same way as motors used as driving power sources in conventional hybrid vehicles and electric vehicles. That is, in addition to functioning as a motor that outputs power when supplied with power from a battery (not shown), the motor is configured to function as a generator that converts mechanical energy (power) into electrical energy (electric power) when rotated by the power transmitted from drive wheels, etc. Specifically, the motor is configured as an AC motor such as a permanent magnet synchronous motor with a permanent magnet built into the rotor, or an induction motor.

[0017] An inverter 21 is provided to control the power exchanged between the motor and the battery. This inverter 21 can be configured similarly to a conventional inverter and is configured to convert DC power output from a battery (not shown) into desired three-phase AC power and output it to the motor, and to convert AC power generated by the motor into DC power and output it to the battery. The inverter 21 is configured, for example, by a switching circuit configured with switching elements such as IGBTs (Insulated Gate Bipolar Transistors) and power MOS (Metal Oxide Semiconductor) transistors, and a switching control circuit that controls the operation of the switching elements. Note that a boost circuit such as a DC-DC converter (not shown) may be provided between the inverter 21 and the battery.

[0018] The engine 1, motor, inverter 21, and a gear train such as a transmission (not shown) are integrated into an electrically and mechanically integrated structure, and are installed in an engine compartment. That is, heat generated by the engine 1 is transferred to the inverter 21 via the eAxle unit such as the motor and transmission. The inverter 21 also generates heat in response to switching operations, electrical resistance, and the like. Therefore, a cooling device 22 is provided to cool the inverter 21, as shown in FIG. 1.

[0019] The cooling device 22 is a water-cooled device and is composed of a circulation path 23 through which cooling water for cooling the inverter 21 circulates, and a water pump (P) 24 that can control the flow rate (flow velocity) of the cooling water flowing through the circulation path 23. The water pump 24 is configured to be able to control the flow rate of the cooling water, for example, by the power of a DC motor (not shown). The circulation path 23 corresponds to the "cooling water circulation path" in the embodiment of the present invention.

[0020] The circulation path 23 is configured to flow around the inverter 21 and exchange heat with the bypass pipe 8. The heat exchange area is indicated by "A," and the heat exchange section A can be configured, for example, by a cylindrical pipe made of a material with high thermal conductivity that surrounds the outer periphery of the bypass pipe 8. Therefore, when the coolant that has absorbed heat and been heated in the inverter 21 flows into the heat exchange section A, the coolant dissipates heat to the intake air flowing through the bypass pipe 8, thereby cooling the coolant. The inverter 21 is provided with a temperature sensor 25 for detecting the temperature of the inverter 21.

[0021] An electronic control unit (hereinafter referred to as ECU) 26 is provided to control the water pump 24. This ECU 26 corresponds to the "controller" in the embodiment of the present invention and can be configured by a microcomputer, similar to a conventional ECU. That is, the ECU 26 is configured to determine an output signal based on input data and pre-stored arithmetic expressions, maps, etc., and to output the determined output signal to the water pump 24.

[0022] The data input to the ECU 26 includes, for example, whether the engine 1 is running, the openings of the throttle valve 12 and the EGR valve 20, the amount of air detected by the air flow meter 11, the temperature detected by the temperature sensor 25, and the like.

[0023] When the hybrid vehicle configured as described above is running with the engine 1 driven, heat generated by the engine 1 is transferred to the inverter 21 via the eAxle unit. Conversely, when the engine 1 is stopped, the amount of heat released from the engine 1 decreases, and so the amount of heat transferred from the engine 1 to the inverter 21 also decreases. Therefore, when the engine 1 is repeatedly started and stopped, the amount of heat release required to control the temperature of the inverter 21 within a predetermined temperature range changes suddenly.

[0024] Therefore, the control device in the embodiment of the present invention is configured to control the flow rate (flow speed) of the coolant from water pump 24 depending on whether engine 1 is running or not. Specifically, when engine 1 is running, the control device is configured to control the flow rate (flow speed) of the coolant from water pump 24 to a predetermined amount or more in order to increase the amount of heat dissipated by inverter 21. Similarly, when engine 1 is stopped, the control device is configured to control the flow rate (flow speed) of the coolant from water pump 24 to less than a predetermined amount in order to reduce the amount of heat dissipated by inverter 21. Note that the control of the flow rate (flow speed) of the coolant from water pump 24 to less than a predetermined amount corresponds to "first control" in the embodiment of the present invention, and the control of the flow rate (flow speed) of the coolant from water pump 24 to be greater than or equal to a predetermined amount corresponds to "second control" in the embodiment of the present invention.

[0025] 2 shows an example comparing the temperature of the inverter 21 (solid line) when the flow rate of the cooling water is controlled depending on whether the engine 1 is running or not, as described above, with the temperature of the inverter 21 (dashed line) when the flow rate of the cooling water is kept constant. The example shown in Fig. 2 shows a case where the engine 1 is repeatedly started and stopped depending on the driving force and vehicle speed required for the vehicle, and the engine 1 is stopped at times t1 and t3, and started at times t2 and t4.

[0026] As shown in FIG. 2, regardless of whether the flow rate of the cooling water is controlled or not, when the engine 1 is running, that is, before time t1, from time t2 to time t3, and from time t4 onwards, the temperature of the inverter 21 rises, and when the engine 1 is stopped, that is, from time t1 to time t2, and from time t3 to time t4, the temperature of the inverter 21 drops.

[0027] On the other hand, when the flow rate of the cooling water is controlled depending on whether the engine 1 is running or not, that is, when the flow rate of the cooling water is controlled to a predetermined amount or more when the engine 1 is running and when the engine 1 is stopped, the flow rate of the cooling water is controlled to a predetermined amount or less, the temperature change rate of the engine 1 is small. In contrast, when the flow rate of the cooling water is kept constant regardless of whether the engine 1 is running or not, the temperature change rate of the engine 1 is large.

[0028] As described above, by controlling the flow rate of the coolant that cools the inverter 21 depending on whether the engine 1 is running or not, it is possible to prevent the temperature of the inverter 21 from changing suddenly. As a result, for example, when the vehicle is traveling using only the power of the motor, it is possible to prevent the temperature of the inverter 21 from rising suddenly and forcing the engine 1 to start in order to increase the amount of heat dissipated by the coolant, thereby preventing a deterioration in fuel efficiency. Furthermore, it is possible to prevent a decrease in the durability of the inverter 21 due to a sudden change in temperature of the inverter 21. [Explanation of symbols]

[0029] 1 engine 4 Intake pipe 7 Intercooler 8 Bypass pipe 9. Flow ratio change valve 21 Inverter 22 Cooling device 23 Circulation path 24 Water pump 25 Temperature Sensor 26 Electronic Control Unit (ECU) A Heat exchange section

Claims

[Claim 1] A control device for a hybrid vehicle, in which an engine and a motor as a driving force source and an inverter for controlling the output of the motor are integrated and installed in an engine room, and which is provided with a cooling water circulation path through which cooling water for cooling the inverter flows and which exchanges heat with an intake pipe of the engine, a water pump capable of changing the flow rate of the cooling water flowing through the cooling water circulation path; a controller for controlling the water pump, The controller The control system is configured to be able to switch between a first control for controlling the flow rate of the cooling water from the water pump to less than a predetermined amount when the engine is stopped, and a second control for controlling the flow rate of the cooling water from the water pump to equal to or greater than the predetermined amount when the engine is running. A control device for a hybrid vehicle.

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