Hybrid vehicle

Abstract

To suppress a sense of discomfort given to a driver of a hybrid vehicle due to starting of an engine caused by dilution of oil for lubricating the engine, and to reduce the dilution of the oil.SOLUTION: A hybrid vehicle according to the present disclosure includes: an engine and an electric motor as driving sources for outputting power for traveling; and a control device. The control device acquires an estimated dilution amount of oil for lubricating the engine. When operation of the engine is stopped, and the estimated dilution amount is equal to or greater than a predetermined engine starting threshold value, the control device forcibly starts the engine and notifies a driver of the hybrid vehicle of the fact that the engine is forcibly started. When the operation of the engine is stopped, and the estimated dilution amount is less than the engine starting threshold value, the control device stepwise changes priority of starting the engine and a mode of notifying the driver of whether stopping of the engine is allowed, on the basis of the estimated dilution amount.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a hybrid vehicle that includes an engine and an electric motor as drive sources that output power for running. [Background technology]

[0002] Conventionally, there is known a vehicle control device that executes warm start control to perform normal control of the engine's operating state when the engine is warm started, and executes cold start control to control the engine's operating state when the engine is cold started so that engine warm-up is promoted compared to the warm start control (see, for example, Patent Document 1). This control device predicts that short trips are occurring repeatedly when the estimated dilution amount of the engine's lubricating oil is equal to or greater than a threshold, and stops the cold start control and executes the warm start control. This promotes engine warm-up, thereby suppressing an increase in diluted fuel and suppressing dilution of the lubricating oil due to the mixing of diluted fuel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-101940 Summary of the Invention [Problem to be solved by the invention]

[0004] In hybrid vehicles, particularly plug-in hybrid vehicles, that include an engine and an electric motor as drive sources, the engine's operating frequency decreases, resulting in fewer opportunities for the engine to warm up. As a result, fuel adhering to the inner walls of the engine's combustion chamber flows down into the oil pan, where it mixes with the lubricating oil and dilutes the lubricating oil. Furthermore, if the amount of lubricating oil diluted by fuel increases, fuel vaporized in the oil pan returns to the combustion chamber as the lubricating oil temperature rises during engine warm-up. The return of vaporized fuel from the oil pan to the combustion chamber disrupts the air-fuel ratio in the combustion chamber, resulting in poor combustion. Furthermore, vaporized fuel may flow from the combustion chamber into the exhaust gas purification device during fuel cutoff, potentially overheating the catalyst due to the fuel combustion in the exhaust gas purification device. To prevent these problems and overheating of the catalyst, a possible solution is to forcibly operate the engine for a predetermined period of time when the lubricating oil dilution level reaches a predetermined level, returning the vaporized fuel to the combustion chamber. However, when a driver wants to run the hybrid vehicle using only power from the electric motor, forcing the engine to operate causes the driver to feel uncomfortable.

[0005] Therefore, the main objective of the present disclosure is to reduce oil dilution while preventing the driver of a hybrid vehicle from feeling uncomfortable when starting the engine due to dilution of the oil that lubricates the engine. [Means for solving the problem]

[0006] The hybrid vehicle disclosed herein is a hybrid vehicle that includes an engine and an electric motor as drive sources that output power for driving, and includes a control device that acquires an estimated dilution amount of oil that lubricates the engine, and when operation of the engine is stopped and the estimated dilution amount is equal to or greater than a predetermined engine start threshold, forcibly starts the engine and notifies the driver of the hybrid vehicle that the engine will be forcibly started, and when operation of the engine is stopped and the estimated dilution amount is less than the engine start threshold, gradually changes the priority of starting the engine and the manner in which the driver is notified as to whether the engine can be stopped, based on the estimated dilution amount.

[0007] A control device for a hybrid vehicle disclosed herein acquires an estimated dilution amount of oil lubricating the engine, and when the engine is stopped and the estimated dilution amount is equal to or greater than a predetermined engine start threshold, forcibly starts the engine and notifies the driver of the forced engine start. This allows the control device to start the engine and reduce oil dilution after notifying the driver of the engine status so as not to cause discomfort when the estimated dilution amount is equal to or greater than the engine start threshold. Furthermore, when the engine is stopped and the estimated dilution amount is less than the engine start threshold, the control device gradually changes the engine start priority and the notification mode to the driver regarding whether or not the engine can be stopped based on the estimated dilution amount. This allows the driver to run the hybrid vehicle using power from both the engine and the electric motor, without abruptly starting the engine, in accordance with the estimated oil dilution amount, while the estimated dilution amount is less than the engine start threshold. As a result, oil dilution can be reduced while effectively preventing the driver from feeling discomfort caused by engine start due to dilution of the oil lubricating the hybrid vehicle's engine. [Brief explanation of the drawings]

[0008] [Figure 1]1 is a schematic configuration diagram showing a hybrid vehicle according to the present disclosure. [Figure 2] 3 is a flowchart illustrating an example of a routine executed by a control device for a hybrid vehicle of the present disclosure. [Figure 3] FIG. 10 is a schematic configuration diagram showing another hybrid vehicle of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, embodiments of the present disclosure will be described with reference to the drawings.

[0010] 1 is a schematic diagram showing a hybrid vehicle (HEV) 1 of the present disclosure. The hybrid vehicle 1 shown in the figure includes an engine 2, a single-pinion planetary gear 3 as a power distribution mechanism, a gear train 4, motor generators MG1 and MG2, both of which are synchronous generator motors (three-phase AC motors), a battery (electricity storage device) 5, a power control device (hereinafter referred to as "PCU") 6 connected to the battery 5 and driving the motor generators MG1 and MG2, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 100 as a control device that controls the entire vehicle.

[0011] The engine 2 of the hybrid vehicle 1 is an internal combustion engine that converts the reciprocating motion of pistons (not shown) that accompanies the combustion of a mixture of hydrocarbon fuel (gasoline) and air in multiple combustion chambers into the rotational motion of a crankshaft (output shaft) CS. However, the engine 2 is not limited to a gasoline engine, and may be an LPG engine or a diesel engine.

[0012] The engine 2 is controlled by an engine electronic control unit (hereinafter referred to as "EGECU") 200. The EGECU 200 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc., not shown, as well as various drive circuits and various logic ICs. The EGECU 200 calculates the rotation speed Ne of the engine 2 (crankshaft CS) based on the crank position from a crank angle sensor not shown, and calculates a load factor KL based on the intake air amount from an air flow meter not shown and the rotation speed Ne of the engine 2. The EGECU 200 then controls the intake air amount, fuel injection amount, ignition timing, etc. of the engine 2 based on the command signal from the HVECU 100, the rotation speed Ne, the load factor KL, etc.

[0013] Furthermore, in the hybrid vehicle 1, while the operation of the engine 2 is stopped, fuel adhering to the inner wall surfaces of each combustion chamber flows down into an oil pan (not shown), and the fuel (gasoline) mixes with the engine oil that lubricates and cools the engine 2, thereby diluting the engine oil. For this reason, the EGECU 200 calculates (estimates) an estimated engine oil dilution amount Doil caused by the mixing of fuel flowing down from each combustion chamber into the oil pan. In this embodiment, during one trip, when the coolant temperature at the start of the engine 2 is below a predetermined temperature, a predetermined time has passed since the start of the engine 2, and the cumulative intake air amount since the start of the engine 2 becomes equal to or greater than a predetermined value, or when the operation of the engine 2 is stopped, the EGECU 200 adds a product of a predetermined base dilution amount and a correction coefficient based on the coolant temperature, etc., to the estimated dilution amount Doil calculated up to that point only once. In addition, every time the operation of the engine 2 continues for a predetermined time (for example, about 30 seconds), the EGECU 200 subtracts the product of a predetermined base subtraction amount and a correction coefficient based on the engine oil temperature from the estimated dilution amount Doil calculated up to that point.

[0014] The planetary gear 3 is a differential rotation mechanism including a sun gear 3s, a ring gear 3r, and a planetary carrier 3c that rotatably supports a plurality of pinion gears 3p. As shown in Fig. 1, the sun gear 3s is connected to the rotor of the motor generator MG1, and the planetary carrier 3c is connected to the crankshaft CS of the engine 2 via a damper mechanism DD. The ring gear 3r, which serves as an output element, rotates coaxially and integrally with the counter drive gear 4a (output member) of the gear train 4.

[0015] In addition to the counter drive gear 4a, the gear train 4 includes a counter driven gear 4b and a final drive gear (drive pinion gear) 4c. The final drive gear 4c meshes with a differential ring gear Dr of the differential gear DF ​​and is connected to left and right wheels (drive wheels) W via the differential gear DF ​​and drive shafts DS. As a result, the planetary gear 3, the gear train 4, and the differential gear DF ​​form a transaxle that transmits a portion of the output torque of the engine 2, which serves as a power generation source, to the wheels W and connects the engine 2 and the motor generator MG1 to each other.

[0016] Motor generator MG1 primarily operates as a generator that converts at least a portion of the power from engine 2, which is operated under load, into electric power. Motor generator MG2 is connected to a pair of left and right wheels W via a differential gear DF, which includes a drive gear 4d, a counter driven gear 4b, a final drive gear 4c, and a differential ring gear Dr, and a drive shaft DS. Motor generator MG2 primarily operates as an electric motor that is driven by at least one of the electric power from battery 5 and the electric power from motor generator MG1 and generates a drive torque on drive shaft DS. Furthermore, motor generator MG outputs regenerative braking torque to the pair of wheels W when braking hybrid vehicle 1.

[0017] The battery 5 is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The battery 5 is managed by a battery management electronic control unit (hereinafter referred to as "battery ECU") 500, which includes a microcomputer having a CPU (not shown) and the like. The battery ECU 500 derives the SOC (charging rate), allowable charging power Win (negative value), allowable discharging power Wout (positive value), and the like of the battery 5 based on the terminal voltage VB of the battery 5, the charging / discharging current IB of the battery 5, the battery temperature Tb of the battery 5, and the like. The hybrid vehicle 1 is configured to be able to charge the battery 5 with power from an external power source (AC power source or DC power source) 50 at home or at a charging station, and includes an on-board charger 7, a charging inlet to which a charging connector from the external power source 50 is connected, and the like.

[0018] The PCU 6 includes a first inverter that drives the motor generator MG1, a second inverter that drives the motor generator MG2, a boost converter that can boost the power from the battery 5 and reduce the power from the motor generators MG1 and MG2 (all of which are not shown), etc. The PCU 6 is controlled by a motor electronic control unit (hereinafter referred to as "MGECU") 600 that includes a microcomputer having a CPU and the like (not shown).

[0019] The HVECU 100 includes a microcomputer having a CPU, ROM, RAM, input / output interfaces, etc. (not shown), various drive circuits, various logic ICs, etc. The HVECU 100 acquires the vehicle speed V detected by a vehicle speed sensor (not shown), the accelerator pedal position Acc indicating the depression amount of the accelerator pedal detected by an accelerator pedal position sensor (not shown), the shift position SP of the shift lever (not shown) detected by a shift position sensor (not shown), etc. The HVECU 100 also exchanges information with the ECUs 200, 500, and 600 and a brake electronic control unit (not shown) that controls a hydraulic brake actuator (not shown), and performs overall control of the hybrid vehicle 1 based on the vehicle speed V, the accelerator pedal position Acc, and signals from the ECUs 200, 500, and 600. The HVECU 100 also displays various information to be notified to the driver on a display unit 10 installed on an instrument panel (not shown) or the like of the hybrid vehicle 1 while the hybrid vehicle 1 is in system startup.

[0020] The driving modes of the hybrid vehicle 1 configured as described above include an EV driving mode (electric driving mode), an auto EV / HV mode, and an HV driving mode (hybrid driving mode). In the EV driving mode, the hybrid vehicle 1 is driven solely by power from the motor generator MG2 driven by power from the battery 5. In the auto EV / HV mode, the hybrid vehicle 1 is driven solely by power from the motor generator MG2 driven by power from the battery 5, and the engine 2 is started to obtain greater torque when the driver depresses the accelerator pedal heavily. In the HV driving mode, the hybrid vehicle 1 is driven solely by power from the engine 2 and power from the motor generator MG2 driven by power from the battery 5.

[0021] 1, a mode selector switch 11 is connected to the HVECU 100, and the driver of the hybrid vehicle 1 can operate the mode selector switch 11 to set a desired one of the EV driving mode, the auto EV / HV mode, and the HV driving mode as the driving mode of the hybrid vehicle 1. Furthermore, when the driving mode is the EV driving mode or the auto EV / HV mode and the SOC of the battery 5 falls below a predetermined threshold, the HVECU 100 automatically shifts the driving mode to the HV mode and starts (restarts) the engine 2 in cooperation with the EGECU 200 and the MGECU 600.

[0022] If the amount of engine oil in the oil pan diluted with fuel increases, the fuel vaporized in the oil pan returns to each combustion chamber as the engine oil temperature rises when the engine 2 is warmed up. Returning the vaporized fuel from the oil pan to each combustion chamber disrupts the air-fuel ratio in each combustion chamber, resulting in poor combustion. The vaporized fuel may then be burned in an exhaust gas purification device (not shown) of the engine 2, potentially overheating the catalyst. Therefore, in the hybrid vehicle 1, when the system is running and the operation of the engine 2 is stopped (mainly when the driving mode is the EV driving mode or the auto EV / HV mode), the HVECU 100 repeatedly executes the routine shown in FIG. 2 at predetermined time intervals to reduce engine oil dilution.

[0023] When the timing for executing the routine of FIG. 2 arrives, the HVECU 100 acquires the estimated engine oil dilution amount Doil calculated (estimated) by the EGECU 200 (step S100). Next, the HVECU 100 determines whether the estimated dilution amount Doil acquired in step S100 is equal to or less than a predetermined engine stop threshold Dstop (step S110). The engine stop threshold Dstop is a value (positive value) previously determined through experiments and analysis as an engine oil dilution amount that does not cause disturbances in the air-fuel ratio in each combustion chamber or overheating of the catalyst. If the estimated dilution amount Doil is equal to or less than the engine stop threshold Dstop (step S110: YES), the HVECU 100 permits the engine 2 to stop without transmitting a start request for the engine 2 to the EGECU 200 and the MGECU 600 (step S120). Furthermore, the HVECU 100 temporarily ends the routine of FIG. 2 without displaying a notification to the driver on the display unit 10 (step S130).

[0024] Furthermore, if the estimated dilution amount Doil acquired in step S100 is greater than the engine stop threshold Dstop (step S110: NO), the HVECU 100 determines whether the estimated dilution amount Doil acquired in step S100 is equal to or less than a predetermined transition recommendation threshold Dtran (step S140). The transition recommendation threshold Dtran is a value (positive value) greater than the engine stop threshold Dstop, which is determined in advance through experiments and analysis as an oil dilution amount that is unlikely to cause disturbances in the air-fuel ratio in each combustion chamber or overheating of the catalyst, but is still preferable for starting the engine 2.

[0025] Furthermore, if the estimated dilution amount Doil is equal to or less than the transition recommendation threshold Dtran (step S140: YES), the HVECU 100 permits the engine 2 to stop operation without transmitting a start request for the engine 2 to the EGECU 200 and the MGECU 600 (step S150). Furthermore, the HVECU 100 displays a predetermined message on the display unit 10 to notify the driver of the recommendation to transition to the HV driving mode (step S160), and temporarily ends the routine of FIG. 2. In step S160, the message displayed on the display unit 10 is, for example, "HV driving mode is recommended to protect the system. Please operate the mode selector switch."

[0026] Furthermore, if the estimated dilution amount Doil acquired in step S100 is greater than the recommended transition threshold Dtran (step S140: NO), the HVECU 100 determines whether the estimated dilution amount Doil acquired in step S100 is less than a predetermined engine start threshold Dstart (step S170). The engine start threshold Dstart is a value (positive value) greater than the recommended transition threshold Dtran, which is highly likely to cause disturbances in the air-fuel ratio in each combustion chamber and overheating of the catalyst, and is determined in advance through experiments and analysis as the amount of oil dilution at which the engine 2 should be started.

[0027] If the estimated dilution amount Doil is less than the engine start threshold Dstart (step S170: YES), the HVECU 100 sets the HV driving mode to the driving mode of the hybrid vehicle 1 so that the engine 2 is started (step S180). Furthermore, the HVECU 100 displays a predetermined message on the display unit 10 to notify the driver that the HV driving mode has been forcibly set to the driving mode and that the HV driving mode setting can be canceled by operating the mode selector switch 11 (step S190), and then temporarily ends the routine of FIG. 2. In step S190, the message displayed on the display unit 10 may be, for example, "The system has been forcibly switched to the HV driving mode to protect the system. You can switch to the EV driving mode by operating the mode selector switch."

[0028] On the other hand, if the estimated dilution amount Doil is equal to or greater than the engine start threshold Dstart (step S170: NO), the HVECU 100 transmits an engine start command to the EGECU 200 and the MGECU 600 to forcibly start the engine 2 (step S200). Furthermore, the HVECU 100 displays a predetermined message on the display unit 10 to notify the driver that the engine 2 will be forcibly started and that the hybrid vehicle 1 will be unable to run solely on power from the motor generator MG2 for a while (step S210), and then temporarily ends the routine of FIG. 2. In step S210, the message displayed on the display unit 10 may be, for example, "The engine has been forcibly started to protect the system. Motor running is not possible until the engine automatically stops."

[0029] In response to the engine start command in step S200, EGECU 200 and MGECU 600 control engine 2 or PCU 6 so that engine 2 is started by the output of cranking torque from motor generator MG1. In this embodiment, after engine 2 is started in response to the engine start command in step S200, operation of engine 2 is stopped when it is determined that the estimated dilution amount Doil has become equal to or less than a predetermined threshold and that the dilution of the engine oil has been substantially eliminated. Then, from the time the engine start command is issued in step S200 until engine 2 is stopped, hybrid vehicle 1 is prohibited from running solely on power from motor generator MG2.

[0030] As described above, the HVECU 100, which is the control device of the hybrid vehicle 1, acquires the estimated dilution amount Doil of the engine oil that lubricates and cools the engine 2 (step S100), and when the operation of the engine 2 is stopped and the estimated dilution amount Doil is equal to or greater than the predetermined engine start threshold Dstart (step S170: NO), the HVECU 100 forcibly starts the engine 2 and notifies the driver of the hybrid vehicle 1 that the engine 2 will be forcibly started (steps S200-S210). As a result, when the estimated dilution amount Doil becomes equal to or greater than the engine start threshold Dstart, the HVECU 100 notifies the driver of the engine 2 of the status of the engine 2 so as not to cause discomfort to the driver, and then starts the engine 2 to reduce the dilution of the engine oil.

[0031] Furthermore, when the operation of the engine 2 is stopped and the estimated dilution amount Doil is less than the engine start threshold Dstart (step S110: YES, step S140: YES, step S170: YES), the HVECU 100 gradually changes the priority of starting the engine 2, i.e., the degree of permission to stop the engine 2 and the notification mode to the driver regarding whether or not the engine 2 can be stopped, based on the estimated dilution amount Doil (steps S120-S130, S150-S160, S180-S190). More specifically, while the estimated dilution amount Doil is less than the engine start threshold Dstart, the priority of starting the engine 2 and the notification mode are changed as follows as the estimated dilution amount Doil increases: stop permission + no notification → stop permission + HV driving mode recommendation → HV driving mode setting + notification thereof. As a result, while the estimated dilution amount Doil is less than the engine start threshold Dstart, the driver can be prompted to run the hybrid vehicle 1 in HV driving mode using power from both the engine 2 and the motor generator MG in accordance with the estimated engine oil dilution amount Doil, without suddenly starting the engine 2. As a result, in the hybrid vehicle 1, it is possible to reduce engine oil dilution while effectively preventing the driver from feeling uncomfortable when the engine 2 starts due to engine oil dilution.

[0032] The driving modes of the hybrid vehicle 1 include an EV driving mode in which the hybrid vehicle 1 is driven only by power from the motor generator MG, and an HV driving mode in which the hybrid vehicle 1 is driven by power from both the engine 2 and the motor generator MG. Furthermore, when the operation of the engine 2 is stopped and the estimated dilution amount Doil is equal to or less than a predetermined engine stop threshold Dstop that is smaller than the engine start threshold Dstart (step S110: YES), the HVECU 100 permits the operation of the engine 2 to be stopped without notifying the driver (steps S120-S130). When the operation of the engine 2 is stopped and the estimated dilution amount Doil is greater than the engine stop threshold Dstop, smaller than the engine start threshold Dstart, and equal to or less than a predetermined transition recommendation threshold Dtran that is larger than the engine stop threshold Dstop (steps S110: NO, S140: YES), the HVECU 100 permits the operation of the engine 2 to be stopped and notifies the driver of the recommendation to set the HV driving mode (steps S150-S160). As a result, when the driver operates the mode selector switch 11 of his / her own volition to set the HV driving mode as the driving mode in response to the recommendation to set the HV driving mode, it becomes possible to start the engine 2 without giving the driver any discomfort, thereby reducing the dilution of the engine oil.

[0033] Furthermore, when the operation of the engine 2 is stopped and the estimated dilution amount Doil is less than the engine start threshold Dstart and greater than the transition recommendation threshold Dtran (step S170: YES), the HVECU 100 sets the HV driving mode to the driving mode and notifies the driver that the HV driving mode has been set to the driving mode (steps S180-S190). This makes it possible to appropriately change the start priority of the engine 2 and create a situation in which the engine 2 is started in a way that reduces engine oil dilution without causing the driver any discomfort.

[0034] Furthermore, when the estimated dilution amount Doil is less than the engine start threshold Dstart and greater than the transition recommendation threshold Dtran and the HV driving mode should be set as the driving mode (steps S180-S190), the HVECU 100 can set the driving mode to the EV driving mode or the auto EV / HV mode in response to a driver's request. That is, the HVECU 100 notifies the driver in step S190 that the HV driving mode setting can be canceled by operating the mode selector switch 11, and sets (maintains) the EV driving mode or the auto EV / HV mode as the driving mode in response to the driver's operation of the mode selector switch 11 after the notification in step S190. This makes it possible to prioritize the driver's desire to set the hybrid vehicle 1 to the EV driving mode, which runs only on power from the motor generator MG, and to satisfy the driver's request.

[0035] Furthermore, the hybrid vehicle 1 can charge the battery 5, which exchanges power with the motor generator MG, using power from an external power source 50. That is, in a so-called plug-in hybrid vehicle (PHEV) 1, the reduced operating frequency of the engine 2 leads to a greater reduction in opportunities for the engine 2 to be warmed up. Therefore, the presently disclosed invention is extremely useful for reducing engine oil dilution while suppressing discomfort felt by the driver in the plug-in hybrid vehicle 1. However, it goes without saying that the presently disclosed invention can also be applied to non-plug-in hybrid vehicles. Furthermore, in the hybrid vehicle 1, a multi-stage transmission may be interposed between the ring gear 3r, which is the output element of the planetary gear 3, and the differential gear DF ​​instead of the gear train 4. The hybrid vehicle of the present disclosure may also be a two-motor hybrid vehicle that does not include the planetary gear 3, or a series hybrid vehicle.

[0036] Furthermore, the presently disclosed invention may be applied to a single-motor hybrid vehicle 1B as shown in FIG. 3. The hybrid vehicle 1B includes a motor-generator (electric motor) MG, a transmission 8, a clutch K0, and a WSC. The transmission 8 is, for example, a 4- to 10-speed multi-speed transmission including an input shaft 8i, an output shaft 8o, multiple planetary gears, and multiple clutches and brakes (gear-shifting engagement elements). The transmission 8 shifts the power transmitted to the input shaft 8i through multiple speeds and outputs it to left and right wheels (rear wheels) W from the output shaft 8o via a differential gear DF ​​and a drive shaft DS. The clutch K0 connects and disconnects the output member of the damper mechanism DD, i.e., the crankshaft CS of the engine 2, and the rotor shaft RS, i.e., the rotor of the motor-generator MG. When the clutch K0 is engaged, the engine 2 (crankshaft CS) is connected to the motor-generator MG via the clutch K0. The clutch WSC connects and disconnects the rotor shaft RS, i.e., the rotor of the motor generator MG, to the input shaft 8i of the transmission 8. When the clutch WSC is engaged, the motor generator MG is connected to the transmission 8 via the clutch WSC.

[0037] In this hybrid vehicle 1B, it is possible to reduce engine oil dilution while effectively preventing the driver from feeling uncomfortable when starting the engine 2 due to engine oil dilution by executing a routine similar to the routine in Fig. 2. Furthermore, the clutch WSC may be omitted from the hybrid vehicle 1B, in which case the input shaft 8i of the transmission 8 may be connected to the output member of the clutch K0 via a lockup clutch and a torque converter.

[0038] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0039] The invention of the present disclosure can be used in the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0040] 1,1B hybrid vehicle, 2 engine, 3 planetary gear, 4 gear train, 5 battery, 6 power control unit (PCU), 7 on-board charger, 8 transmission, 10 display unit, 11 mode selector switch, 50 external power supply, 100 hybrid electronic control unit (HVECU), 200 engine electronic control unit (EGECU), 600 motor electronic control unit (MGECU), MG, MG1, MG2 motor generators.

Claims

1. In a hybrid vehicle including an engine and an electric motor as a drive source that outputs power for running, A hybrid vehicle equipped with a control device that acquires an estimated dilution amount of oil that lubricates the engine, and when the engine is stopped and the estimated dilution amount is equal to or greater than a predetermined engine start threshold, forcibly starts the engine and notifies the driver of the hybrid vehicle that the engine will be forcibly started, and when the engine is stopped and the estimated dilution amount is less than the engine start threshold, gradually changes the priority of starting the engine and the manner in which the driver is notified as to whether the engine can be stopped, based on the estimated dilution amount.

2. 2. The hybrid vehicle according to claim 1, the driving modes of the hybrid vehicle include an electric driving mode in which the hybrid vehicle is driven only by power from the electric motor, and a hybrid driving mode in which the hybrid vehicle is driven by power from both the engine and the electric motor, The control device allows the engine to be stopped without notifying the driver when the engine is stopped and the estimated dilution amount is equal to or less than a predetermined engine stop threshold that is smaller than the engine start threshold, and allows the engine to be stopped and notifies the driver of the recommendation to set the hybrid driving mode when the engine is stopped and the estimated dilution amount is greater than the engine stop threshold, smaller than the engine start threshold, and smaller than a predetermined transition recommendation threshold that is larger than the engine stop threshold.

3. 3. The hybrid vehicle according to claim 2, When the engine is stopped and the estimated dilution amount is less than the engine start threshold and greater than the transition recommendation threshold, the control device sets the hybrid driving mode to the driving mode and notifies the driver that the hybrid driving mode has been set to the driving mode.

4. 4. The hybrid vehicle according to claim 3, The control device sets the electric driving mode to the driving mode in response to a request from the driver when the estimated dilution amount is less than the engine start threshold and greater than the recommended transition threshold and the hybrid driving mode should be set to the driving mode.

5. 2. The hybrid vehicle according to claim 1, The hybrid vehicle further includes a battery that exchanges electric power with the electric motor, and the battery can be charged with electric power from an external power source.

Images