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 valve stop mechanism provided in the engine to stop an engine valve of the engine in a valve closing state without depending on revolution of the engine; and a control device that controls the valve stop mechanism to stop the engine valve in the valve closing state in a motor traveling mode in which the engine is stopped and traveling is performed by the second motor generator.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 one another via the planetary gear mechanism, a hydraulic lash adjuster provided to the engine, a valve stop mechanism provided to the engine for stopping engine valves in a closed state regardless of engine rotation, and a control device for controlling the valve stop mechanism to stop the engine valves in a closed state in a motor driving mode in which the engine is stopped and the vehicle is driven by the second motor-generator. [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. 2 is a schematic diagram of the engine. [Figure 3] FIG. 3A is an example of a nomographic diagram showing the rotation speeds of the first MG, the engine, and the second MG during deceleration in the motor driving mode, and FIG. 3B is a flowchart illustrating the valve stop 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 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 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 ECU 100 is an electronic control unit including a processing circuit for performing various types of 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.

[0013] 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.

[0014] 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.

[0015] [Engine outline] FIG. 2 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.

[0016] 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 hydraulic. The same applies to the rocker arm 42 and the lash adjuster 44.

[0017] The valve train 51 includes a camshaft, an arm that receives input from the camshaft's cam, an arm that abuts against the rocker arm, and a connecting pin that connects and disconnects these two arms. When the two arms are connected, the input from the intake cam is transmitted to the rocker arm via the two arms, thereby driving the intake valve 31. When the two arms are disconnected, the input from the intake cam is no longer transmitted from one arm to the other, and the intake valve 31 is stopped in a closed state. The same applies to the valve train 52. The connection state of the two arms by the connecting pin is switched depending on the oil pressure supplied to the connecting pin, and the oil pressure is adjusted by an oil control valve. The valve trains 51 and 52 are examples of valve stop mechanisms.

[0018] FIG. 3A 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, engine 10 rotation 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 camshaft 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 of the lash adjusters 43 and 44. For this reason, the ECU 100 executes the following valve stop control.

[0019] [Valve stop control] FIG. 3B is a flowchart illustrating valve stop control executed by ECU 100. ECU 100 determines whether the driving mode is the motor driving mode (step S1). In other words, it is determined whether the driving mode is one in which engine 10 is stopped. If the answer is No in step S1, this control ends. If the answer is Yes in step S1, ECU 100 controls valve mechanisms 51 and 52 to execute valve stop, which maintains intake valve 31 and exhaust valve 32 in a closed state (step S2). As a result, the inside of cylinder 11 is sealed, and the rotational resistance of crankshaft 14 increases. Therefore, as described above, even during deceleration in motor driving mode, oscillation of crankshaft 14 is suppressed, and the outflow of lubricating oil from lash adjusters 43 and 44 is suppressed.

[0020] Next, the ECU 100 determines whether the driving mode is a hybrid driving mode (step S3). In other words, it determines whether the driving mode is one in which the engine 10 is driven. If the answer is No in step S3, this control ends. If the answer is Yes in step S3, the ECU 100 controls the valve mechanisms 51 and 52 to cancel the valve stop (step S4). As a result, the intake valve 31 and the exhaust valve 32 are driven when the engine 10 is driven, ensuring the operability of the engine 10.

[0021] It should be noted that, with regard to the above-described valve stopping, it is also possible to keep the valves of only one of the plurality of cylinders 11 from being stopped, thereby suppressing a decrease in the startability of the engine 10.

[0022] The valve stopping mechanism is not limited to the above-described valve operating mechanisms 51 and 52. For example, the valves may be maintained in a stopped state by an engine that does not have a camshaft and is equipped with electromagnetic intake and exhaust valves.

[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 31 Intake valve (engine valve) 32 Exhaust valve (engine valve) 43, 44 Lash adjuster 51, 52 Valve train (valve stop mechanism) 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 valve stopping mechanism provided in the engine for stopping an engine valve of the engine in a closed state without depending on the rotation of the engine; a control device that controls the valve stop mechanism to stop the engine valve in a closed state in a motor running mode in which the engine is stopped and the vehicle is running using the second motor generator.

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