Hybrid vehicle

Abstract

To provide a hybrid vehicle that suppresses oscillation of a crank shaft in a motor traveling mode.SOLUTION: A hybrid vehicle includes: a planetary gear mechanism; an engine, a first motor generator and a second motor generator coupled to each other via the planetary gear mechanism; a hydraulic lash adjuster provided in the engine; a starter motor for cranking the engine at start of the engine; an actuator that connects or shuts off power transmission between the starter motor and the engine; and a control device that controls the actuator to connect the power transmission in a motor traveling mode in which the engine is stopped and traveling is performed by the second motor generator and that energizes the starter motor by using an energizing amount smaller than that to the starter motor at start of the engine during deceleration in the motor traveling mode.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to hybrid vehicles. [Background technology]

[0002] BACKGROUND ART A hybrid vehicle is known that includes an engine, a first motor generator, and a second motor generator that are connected to one another via a planetary gear mechanism (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-147124 Summary of the Invention [Problem to be solved by the invention]

[0004] When the vehicle decelerates while running in motor drive mode, where the engine is stopped and the vehicle is propelled by the second motor / generator, the crankshaft may oscillate, which may cause lubricating oil to leak out of the lash adjuster. This may result in a lack of lubricating oil in the lash adjuster when the engine is started, which may cause abnormal noise.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hybrid vehicle that suppresses swing of the crankshaft in the motor driving mode. [Means for solving the problem]

[0006] The above object can be achieved by a hybrid vehicle including a planetary gear mechanism, an engine, a first motor generator, and a second motor generator connected to each other via the planetary gear mechanism, a hydraulic lash adjuster provided on the engine, a starter motor that cranks the engine when it is started, an actuator that connects or disconnects power transmission between the starter motor and the engine, and a control device that controls the actuator to connect the power transmission in a motor driving mode in which the engine is stopped and the vehicle is driven by the second motor generator, and that energizes the starter motor with an amount of current that is less than the amount of current supplied to the starter motor when the engine is started, during deceleration in the motor driving mode. [Effects of the Invention]

[0007] A hybrid vehicle can be provided in which the swing of the crankshaft is suppressed in the motor driving mode. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle. [Figure 2] FIG. 2A is a schematic diagram of the engine, and FIG. 2B is an example of a collinear diagram showing the rotation speeds of the first MG, the engine, and the second MG during deceleration in the motor running mode. [Figure 3] FIG. 3 is a timing chart illustrating the crankshaft fluctuation suppression control executed by the ECU. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Hybrid vehicle configuration] 1 is a schematic diagram of a hybrid vehicle 1. The hybrid vehicle 1 includes an engine 10, a starter device 15, a first motor generator (hereinafter referred to as the first MG) 61, a second motor generator (hereinafter referred to as the second MG) 62, a planetary gear mechanism 63, a transmission mechanism 64, drive wheels 70, a PCU 80, a battery 90, and an ECU (Electronic Control Unit) 100. The engine 10, the first MG 61, and the second MG 62 are mounted as drive sources for driving the hybrid vehicle 1.

[0010] The first MG 61 and the second MG 62 are connected to the battery 90 via the PCU 80. The first MG 61 and the second MG 62 function as motors that generate driving force for the vehicle in response to power supplied from the battery 90. Furthermore, the first MG 61 and the second MG 62 also function as generators that generate regenerative power to charge the battery 90 in response to power transmission from the engine 10 and the drive wheels 70. The power exchanged between the first MG 61 and the second MG 62 and the battery 90 is regulated by the PCU 80. The PCU 80 is controlled by the ECU 100. The PCU 80 converts a DC voltage from the battery 90 into an AC voltage, or converts an AC voltage from the first MG 61 or the second MG 62 into a DC voltage.

[0011] The planetary gear mechanism 63 mechanically couples the crankshaft of the engine 10, the rotating shaft of the first MG 61, the rotating shaft of the second MG 62, and the output shaft of the planetary gear mechanism 63. The planetary gear mechanism 63 includes a sun gear that rotates on its own axis, a ring gear that rotates coaxially with the sun gear, a pinion gear that is interposed between the sun gear and the ring gear and revolves around the sun gear, and a carrier that rotates coaxially with the sun gear in accordance with the revolution of the pinion gear. The carrier is coupled to the crankshaft 14 of the engine 10. The sun gear is coupled to the rotating shaft of the first MG 61. The ring gear is interlocked with the rotating shaft of the second MG 62. The driving forces of the engine 10, the first MG 61, and the second MG 62 are transmitted to the drive wheels 70 via a transmission mechanism 64.

[0012] The starter device 15 cranks the engine 10 when the engine 10 is started. The starter device 15 includes a starter motor 15m, a gear 15g, and an actuator 15a. Rotation of the starter motor 15m rotates the gear 15g attached to the rotary shaft of the starter motor 15m. A gear 14g is provided on the crankshaft 14 of the engine 10. The actuator 15a moves the gear 15g from a separated position separated from the gear 14g to an engaged position engaged with the gear 14g. When the gear 15g is in the separated position, power transmission between the starter motor 15m and the engine 10 is interrupted. When the gear 15g is in the engaged position, power transmission between the starter motor 15m and the engine 10 is connected. Therefore, by driving the starter motor 15m while the power transmission is connected, the crankshaft 14 can be forcibly rotated. The starter motor 15m and the actuator 15a are controlled by the ECU 100.

[0013] The ECU 100 is an electronic control unit including a processing circuit for performing various calculations related to vehicle driving control and a memory for storing control programs and data. The ECU 100 is an example of a control device for the hybrid vehicle 1.

[0014] The ECU 100 is electrically connected to a sensor group 101. The sensor group 101 includes an accelerator position sensor, a brake position sensor, a crank angle sensor, and a vehicle speed sensor. The accelerator position sensor and the brake position sensor detect the accelerator position and the brake position, which are the amounts of operation of the accelerator pedal and the brake pedal, respectively. The crank angle sensor detects the rotation speed of the crankshaft 14 of the engine 10. The vehicle speed sensor detects the vehicle speed of the hybrid vehicle 1.

[0015] The ECU 100 switches the driving mode between a motor driving mode and a hybrid driving mode. In the motor driving mode, the vehicle drives using the second MG 62 as a power source while the engine 10 is stopped. In the hybrid driving mode, the engine 10 is driven and the vehicle drives using the engine 10 as a power source. The hybrid driving mode also includes the case where at least one of the first MG 61 and the second MG 62 is used in conjunction with the engine 10.

[0016] The driving mode is switched based on the torque required for the hybrid vehicle 1, which is calculated from the vehicle speed and accelerator opening. For example, if the required torque is less than a start threshold for starting the engine 10, a motor driving mode in which the engine 10 is stopped is selected to improve fuel efficiency. If the required torque is equal to or greater than the start threshold for starting the engine 10, a hybrid driving mode in which the engine 10 is started is selected.

[0017] [Engine outline] 2A is a schematic diagram of an engine 10 according to this embodiment. The engine 10 is a gasoline engine having multiple cylinders 11, but is not limited to this and may be a diesel engine. Within the cylinder 11, a piston 12 reciprocates in conjunction with a crankshaft 14. Within the cylinder 11, an ignition plug 13 is provided for igniting the air-fuel mixture. An intake pipe 21 and an exhaust pipe 22 are connected to the cylinder 11. An intake valve 31 opens and closes the connection between the intake pipe 21 and the cylinder 11. An exhaust valve 32 opens and closes the connection between the exhaust pipe 22 and the cylinder 11. The intake valve 31 and the exhaust valve 32 are examples of engine valves.

[0018] The intake valve 31 and the exhaust valve 32 are driven by rocker arms 41 and 42, respectively. One end of the rocker arm 41 abuts against the upper end of the intake valve 31, and a lash adjuster 43 supports the other end of the rocker arm 41. A plunger of the lash adjuster 43 presses against the other end of the rocker arm 41, thereby maintaining one end of the rocker arm 41 in abutment against the upper end of the intake valve 31. The lash adjuster 43 is hydraulically driven. The same is true for the rocker arm 42 and the lash adjuster 44. An intake camshaft 51 and an exhaust camshaft 52 drive the rocker arms 41 and 42, respectively.

[0019] FIG. 2B is an exemplary nomographic diagram showing the rotation speeds of the first MG 61, engine 10, and second MG 62 during deceleration in motor driving mode. The dotted line indicates the rotation speed before deceleration, and the solid line indicates the rotation speed after deceleration. Before deceleration, the second MG 62 outputs positive torque in the forward rotation direction, and the rotation of the engine 10 is stopped due to friction torque of the engine 10, and the first MG 61 idles in the reverse rotation direction. When the rotation speed of the second MG 62 in the forward rotation direction decreases due to a deceleration request, the decrease in the rotation speed of the first MG 61 is smaller than the decrease in the rotation speed of the second MG 62 due to the inertia torque of the first MG 61 in the reverse rotation direction. As a result, the inertia torque of the first MG 61 becomes larger than the friction torque of the engine 10, causing the engine 10 to rotate slightly in the reverse rotation direction. When the inertia torque of the first MG 61 decreases, the inertia torque of the first MG 61 becomes smaller than the friction torque of the engine 10, causing the crankshaft 14 to rotate slightly in the forward rotation direction. As described above, during deceleration in the motor drive mode, the crankshaft 14 of the engine 10 oscillates, causing the intake camshaft 51 and the exhaust camshaft 52 to oscillate as well. As a result, the plungers of the lash adjusters 43 and 44 move up and down via the rocker arms 41 and 42, which could cause lubricating oil to leak out from the lash adjusters 43 and 44. For this reason, the ECU 100 executes the following crankshaft oscillation suppression control.

[0020] [Crankshaft oscillation suppression control] 3 is a timing chart illustrating the crankshaft vibration suppression control executed by the ECU 100. FIG. 3 shows the transitions of the accelerator opening, brake opening, vehicle speed, starter control, and engine speed. When the accelerator opening decreases during driving in the hybrid driving mode, the engine 10 stops and the driving mode is switched to one in which the vehicle is driven by the second MG 62 (time t1). At this time, the ECU 100 controls the actuator 15a to move the gear 15g to the engaged position, thereby connecting the power transmission between the starter motor 15m and the engine 10. This adds resistance from the starter motor 15m to the rotation of the crankshaft 14, increasing the resistance to the above-mentioned vibration of the crankshaft 14.

[0021] Next, when the brake opening degree increases significantly above 0, the ECU 100 drives the starter motor 15m (time t2). The amount of current supplied to the starter motor 15m at this time is set to be less than the amount of current supplied to the starter motor 15m when the engine 10 is started, and is set to be such that the crankshaft 14 is not rotated by the starter motor 15m. For example, if the amount of current supplied to the starter motor 15m when the engine 10 is started is 100%, the amount of current supplied to the starter motor 15m at time t2 is less than that, for example, 10%. As a result, torque in the forward rotation direction is applied to the crankshaft 14 from the starter motor 15m, thereby suppressing the reverse rotation of the crankshaft 14 as described above. As a result, the swing of the crankshaft 14 is suppressed.

[0022] When the brake pedal depression becomes zero and the accelerator pedal depression increases, the ECU 100 starts cranking the engine 10 using the starter motor 15m (time t3). At this time, the amount of current supplied to the starter motor 15m is controlled to 100%, as described above. When the engine 10 starts, the ECU 100 controls the actuator 15a to move the gear 15g from the engaged position to the disengaged position (time t4). In this way, the engine 10 starts and the driving mode is switched to the hybrid driving mode.

[0023] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0024] 1 Hybrid vehicle 10 Engine 14 crankshaft 15 Starter device 15m starter motor 15a Actuator 43, 44 Lash adjuster 61 First motor generator 62 Second motor generator 63 Planetary gear mechanism 100 ECU (control unit)

Claims

[Claim 1] A planetary gear mechanism; an engine, a first motor generator, and a second motor generator connected to each other via the planetary gear mechanism; a hydraulic lash adjuster provided on the engine; a starter motor that cranks the engine when the engine is started; an actuator that connects or disconnects power transmission between the starter motor and the engine; a control device that controls the actuator to connect the power transmission in a motor driving mode in which the engine is stopped and the vehicle is driven by the second motor generator, and that energizes the starter motor with an amount of current that is less than the amount of current that is supplied to the starter motor when the engine is started during deceleration in the motor driving mode.

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