JP3616053B2 - Power transmission device for hybrid vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power transmission device for a hybrid vehicle provided with two types of driving force sources of an engine and a motor, and in particular, an engine starting means for starting an engine when shifting from a motor independent traveling mode to a traveling mode with engine driving. The present invention relates to a power transmission device for a hybrid vehicle.
[0002]
[Prior art]
In hybrid vehicles equipped with two types of driving force sources, engine and motor, the engine and motor are selectively connected to the driving wheel side, and each driving output is selectively transmitted to the driving wheel. There is something to do.
[0003]
For example, Japanese Patent Application Laid-Open Nos. 60-55803 and 2000-224714 propose a technique for starting an engine using the rotational force of a travel motor or an axle during a motor single travel mode (EV travel mode). ing. In these hybrid vehicles, the engine can be started by connecting the clutch between the motor and the axle and connecting the clutch between the motor and the engine during traveling in the motor single traveling mode.
[0004]
FIG. 4 is a schematic configuration diagram of a conventional hybrid vehicle power transmission device. The hybrid vehicle power transmission device 20 includes an engine 1 and a motor 2, and can output a vehicle drive output from at least one of the engine 1 and the motor 2 in a plurality of travel modes including a motor single travel mode. A main shaft 7 is connected to an end portion of the crankshaft 5 of the engine 1 via a flywheel 6 with a damper. A motor (generator) 2, a drive mode switching unit 14, and a drive pulley (DR pulley) 9 are arranged on the main shaft 7 coaxially. A driven pulley (DN pulley) 12 and torque transmission are parallel to the main shaft 7. A starting clutch 4 having a variable capacity is arranged. In the hybrid vehicle power transmission device 20, the clutch 3 and the clutch 4 are connected in the motor single traveling mode, the motor power is transmitted to the drive wheels to travel, and the motor single traveling mode shifts to the traveling mode with engine drive. In this case, the engine 1 is started by connecting the clutch 8 disposed between the engine 1 and the motor 2 and transmitting the driving force of the motor 2 to the engine 1.
[0005]
[Problems to be solved by the invention]
However, since the conventional structure is such that the end of the crankshaft 5 of the engine 1 is connected to the motor 2 via the flywheel 6 with a damper, the main shaft 7, and the drive mode switching portion 14, the engine is started when the engine is started. In addition to the friction of 1, it is affected by the inertial mass of the flywheel 6 and the like. For this reason, in order to instantly start the engine 1 without giving the driver a sense of incongruity, the necessary torque increases due to the above-described influence. Therefore, it is necessary to increase the output of the motor 2 accordingly.
However, when the output of the motor 2 is increased, the motor 2 is increased in size accordingly, so that there is a problem that the weight is increased and the mountability is deteriorated. Further, when the motor 2 is increased in size, there is a problem that the voltage of the battery to be supplied is increased and the cost is increased.
[0006]
The present invention has been made in view of such circumstances, and provides a vehicle power transmission device capable of shifting from a motor single travel mode to a travel mode with engine drive without increasing the size of the motor. Objective.
[0007]
[Means for Solving the Problems]
The invention described in claim 1, which has been made to solve the above problems, includes an engine (for example, the engine 31 in the embodiment) and a motor (for example, the motor 32 in the embodiment), and at least a driving force of only the motor. Applied to a hybrid vehicle capable of traveling in a traveling mode in which the motor travels alone, and includes a clutch (for example, the clutch 33 in the embodiment) that is interposed between the engine and the motor and connects or separates the engine and the motor. The hybrid vehicle power transmission device (for example, the hybrid vehicle power transmission device 30 in the embodiment) can start the engine by the driving force of the motor by connecting the engine and the motor by the clutch in the motor single travel mode. The rotor of the motor (for example, in the embodiment) That the rotor 34) the flywheel with a rotatable damper (for example, with, provided with damper flywheel 35) in the embodiment between the motor and the clutch, the damper of the damper flywheel, the rotor of the motor And the flywheel, a hybrid vehicle power transmission device.
[0008]
If comprised as mentioned above, the said flywheel will rotate integrally with the rotor of the said motor in motor independent travel mode. For this reason, the torque due to inertia (inertia) of the flywheel can be reduced from the torque required when the clutch is connected to shift from the motor independent traveling mode to the traveling mode with engine driving. In addition, since the flywheel is provided with a damper, it is possible to absorb engine friction during the transition to the travel mode described above, and to reduce torque due to friction from the required torque. Therefore, since the torque required for the motor can be significantly reduced, the motor can be reduced in size, the mounting property can be improved, and the cost can be reduced. In addition, as described above, since the impact can be reduced at the time of traveling mode transition, the driver is not given a sense of incongruity and comfort can be enhanced.
[0009]
According to a second aspect of the present invention, the flywheel with a damper includes an engine-side flywheel (for example, the engine-side flywheel 36 in the embodiment) and a motor-side flywheel (for example, the motor-side flywheel in the embodiment). A compression spring (for example, the compression spring 38 in the embodiment) and a damping mechanism (for example, the damping mechanism 39 in the embodiment) interposed between them. It is the power transmission device for hybrid vehicles characterized by having it.
[0010]
If comprised as mentioned above, the resonant frequency of the said flywheel with a damper can be set low. By adjusting the value of the resonance frequency so as to be equal to or lower than the practical use range of the engine, it is possible to greatly improve the shock absorbing performance against torque fluctuation. This adjustment can be performed by selecting the values of the spring constant (k) of the compression spring, the damping constant (c) of the damping mechanism, and the inertia moments (J1, J2) of the engine side and motor side flywheels.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a hybrid vehicle power transmission device 30 (hereinafter simply referred to as a power transmission device 30) according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a power transmission device 30 according to an embodiment of the present invention. The power transmission device 30 includes an engine 31 and a motor (generator) 32 as driving force sources.
[0012]
An engine separating clutch 33 is connected between the engine 31 and the motor 32 to connect or separate them. The clutch 33 is connected to the crankshaft 40 of the engine 31 and is of a variable transmission capacity type. By connecting or disconnecting the clutch 33, the driving force is transmitted or interrupted between the engine 31 and the motor 32.
A damper-equipped flywheel 35 is provided between the clutch 33 and the motor 32. The flywheel 35 is connected to a main shaft 42 of a transmission 41, which will be described in detail later, and is rotatable with the rotor 34 of the motor 32.
[0013]
FIG. 2 is a schematic sectional view showing a skeleton of the flywheel 35 of FIG. As shown in the figure, the flywheel 35 includes an engine-side flywheel 36 and a motor-side flywheel 37, which are integrally formed by a compression spring 38 and a damping mechanism 39 interposed therebetween. It is connected. Since it did in this way, the resonant frequency of the flywheel 35 with a damper can be set low. By adjusting the value of the resonance frequency so that the frequency is equal to or lower than the practical use range of the engine 31, the shock absorbing performance against torque fluctuation can be greatly enhanced. This adjustment is performed by selecting the values of the spring constant (k) of the compression spring 38, the damping constant (c) of the damping mechanism 39, and the moments of inertia (J1, J2) of the engine-side and motor-side flywheels 36, 37. It can be carried out.
[0014]
In the present embodiment, the transmission 41 is a continuously variable transmission (CVT) 41, and a drive pulley (DR pulley) 43 is connected coaxially with the main shaft 42. The drive pulley 43 is driven via a belt 44. It is connected to a pulley (DN pulley) 45. A driven shaft 46 is connected to the axis of the driven pulley 45.
[0015]
A forward / reverse switching mechanism 55 is interposed between the drive pulley 43 and the motor 32. The forward / reverse switching mechanism 55 includes a planetary gear mechanism, a forward clutch 54, and a reverse brake 56. The planetary gear mechanism includes a sun gear 58 provided on the main shaft 42, a planetary gear 59 that is rotatably supported by the carrier 57 and meshes with the sun gear 58, and a ring that meshes with the planetary gear 59. And a gear 60. The sun gear 58 is directly connected to the main shaft 42, and the carrier 57 is directly connected to the drive pulley 43, and the ring gear 60 can be intermittently operated with a casing (not shown) serving as a fixed portion by a reverse brake 56. The forward clutch 54 is configured to directly connect the sun gear 58 and the carrier 57. The forward clutch 54 is interposed between the main shaft 42 and the carrier 57 and intermittently connects them. The reverse brake 56 is intermittently connected to a casing (not shown) serving as a fixed portion. By connecting or disconnecting the brake 56, the rotational force of the engine 31 or the motor 32 is transmitted to the drive pulley 43 in the same direction or in the reverse direction.
[0016]
The driven shaft 46 is provided with an output gear 47, and a starting clutch 50 is interposed between the two, and the driving force transmitted to the driven shaft 46 is output by connecting or disconnecting the starting clutch 50. It is transmitted to or cut off from the gear 47. A secondary shaft 48 is juxtaposed with the driven shaft 46, and a gear 48 provided on the secondary shaft 51 is engaged with the output gear 47. The secondary shaft 51 is provided with a gear 49 and a differential gear 52 connected to a wheel 53 is connected thereto. As a result, the driving force transmitted to the output gear 47 is transmitted to the wheel 53 via the gear 49 and the differential gear 52.
[0017]
The vehicle to which the power transmission device 30 is applied has a plurality of travel modes. These travel modes include “EV start mode”, “EV cruise mode”, “MOT assist mode”, “ENG travel mode”, “ENG reverse mode”, “EV reverse mode”, and “stop power generation mode”. is there.
[0018]
The “EV start mode” is a travel mode that is selected when the engine 31 starts in a relatively low acceleration range where the combustion efficiency is poor, and the vehicle is driven only by the driving force of the motor 32 without being driven by the engine 31. The “EV cruise mode” is a travel mode that is selected during a cruise in a relatively low vehicle speed range where the combustion efficiency of the engine 31 is poor, and in which the engine 31 is not driven and the vehicle is driven by the driving force of the motor 32. The “MOT assist mode” is a travel mode that is selected at the time of acceleration from the low vehicle speed range to the high vehicle speed range where the combustion efficiency of the engine 31 is good and assists the driving force of the engine 31 by the driving force of the motor 32. The “ENG travel mode” is a travel mode that is selected when traveling in the above-described high vehicle speed range, and the vehicle is traveled only by the driving force of the engine 31 without being driven by the motor 32. The “ENG reverse mode” is a traveling mode that is selected when traveling in the above-described high vehicle speed range and causes the vehicle to reverse by the driving force of the engine 31. The “EV reverse mode” is a traveling mode that is selected during traveling in the low acceleration range described above and causes the vehicle to move backward by the driving force of the motor 32. The “power generation mode when the vehicle is stopped” is a travel mode that is selected when the vehicle is stopped and generates power by driving the motor 32 as a generator with the driving force of the engine 31.
Transition to each travel mode is performed by switching the coupling element (engine separation clutch) as described below. The switching of these coupling elements is performed by a control device (ECU) (not shown).
[0019]
FIG. 3 is a state explanatory view showing the relationship between the driving mode and the coupling element of the hybrid vehicle of FIG. In the figure, “◯” indicates a combined (connected) state, and “×” indicates a non-connected (separated) state. In the “EV start mode”, the engine separation clutch 33 and the reverse brake 56 are separated, and the start clutch 50 and the forward clutch 54 are connected. Thereby, only the driving force of the motor 32 is transmitted to the wheel 53. The same applies to the “EV cruise mode”. Thus, since the engine 31 is not driven in a low vehicle speed range where the combustion efficiency of the engine 31 is poor, fuel efficiency can be improved.
[0020]
In the “MOT assist mode”, only the reverse brake 56 is separated, and the engine separation clutch 33, the start clutch 50, and the forward clutch 54 are connected. The “ENG travel mode” is the same as the “MOT assist mode”.
When shifting from the “EV start mode” or “EV cruise mode” to “MOT assist” or “ENG travel mode”, the transmission capacity of the engine separation clutch 33 is controlled by a hydraulic control unit (not shown) to separate the engine. The clutch 33 is engaged and the engine 31 is started.
[0021]
At this time, in order not to give the driver a sense of incongruity, it is desired to start the engine 31 quickly and suppress the impact on the vehicle body as much as possible. Therefore, the energy required for starting the engine 31 is required for the motor 32 in addition to the energy required for the motor traveling alone. The starting torque of the engine 31 is related to the friction and inertial mass of the engine 31, but as described above, the flywheel 35 rotates integrally with the rotor 34 of the motor 32 in the motor single travel mode. . For this reason, it is possible to reduce the torque due to the inertia of the flywheel 35 from the torque required when shifting from the motor independent traveling mode to the traveling mode involving driving of the engine.
[0022]
In addition, since the flywheel 35 is provided with a damper function by the compression spring 38 and the damping mechanism 39, the flywheel 35 can absorb the friction of the engine 31 at the time of traveling mode shift, and from the required torque. Torque due to friction can be reduced. Therefore, since the torque required for the motor 32 can be significantly reduced, the motor 32 can be reduced in size, the mountability can be improved, and the cost can be reduced. In addition, since the impact can be reduced at the time of traveling mode transition, the driver can be provided with an uncomfortable feeling and comfort can be enhanced.
[0023]
In the “ENG reverse mode”, only the forward clutch 54 is separated, and the engine separation clutch 33, the start clutch 50, and the reverse brake 56 are connected. As a result, the driving force of the engine 31 is reversed and transmitted to the wheels 53, so that the vehicle moves backward. At this time, the motor 32 stops or functions as the generator 32.
In the “EV reverse mode”, the engine separation clutch 33 is further separated from the “ENG reverse mode” so that the driving force of the engine 31 is not transmitted to the wheels 53.
In the “stop power generation mode”, only the engine separation clutch 31 is connected, and the start clutch 50, the reverse brake 56, and the forward clutch 54 are separated. As a result, the driving force is not transmitted to the wheel 53 and the vehicle 53 is stopped, and the motor 32 is used as the generator 32 by the driving force of the engine 31 to generate power. Therefore, electric power sufficient to drive the motor 32 when the vehicle is stopped can be stored, so that it is possible to smoothly shift to the “EV start mode” or “EV cruise mode” in the low vehicle speed range described above.
[0024]
As described above, the vehicle power transmission device 20 according to the present embodiment can shift from the motor independent traveling mode to the traveling mode with engine driving without increasing the size of the motor 32.
In the above embodiment, the case where a continuously variable transmission (CVT) is used as the transmission has been described. However, the present invention is not limited to this, and a stepped transmission may be used.
[0025]
【The invention's effect】
As described above, according to the first aspect of the present invention, the torque caused by the inertia (inertia) of the flywheel from the torque required when shifting from the motor independent traveling mode to the traveling mode with engine driving. In addition, torque due to friction can be reduced. Therefore, since the torque required for the motor can be significantly reduced, the motor can be reduced in size, the mounting property can be improved, and the cost can be reduced. In addition, since the impact at the time of traveling mode transition can be reduced, the driver can be provided with a sense of incongruity and comfort can be enhanced.
[0026]
According to the second aspect of the present invention, since the resonance frequency of the flywheel with a damper can be set low, the value of the resonance frequency is adjusted so as to be equal to or lower than the practical use range of the engine. As a result, the shock absorbing performance against torque fluctuation can be greatly enhanced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a hybrid vehicle power transmission device according to a first embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing the flywheel of FIG.
3 is a state explanatory view showing a relationship between a driving mode and a coupling element of the hybrid vehicle of FIG. 1; FIG.
FIG. 4 is a schematic explanatory diagram of a conventional hybrid vehicle power transmission device.
[Explanation of symbols]
30 Power transmission device 31 for hybrid vehicle 31 Engine 32 Motor 33 Clutch 34 Rotor 35 Flywheel 36 with damper Engine side flywheel 37 Motor side flywheel 38 Compression spring 39 Damping mechanism

Claims (2)

A clutch that is applied to a hybrid vehicle that includes an engine and a motor and that can run in at least a motor independent running mode that runs with a driving force of only the motor, and that is interposed between the engine and the motor to connect or disconnect the engine and the motor. A power transmission device for a hybrid vehicle capable of starting the engine by the driving force of the motor by connecting the engine and the motor by the clutch in the motor single travel mode,
Provided rotor damper flywheel rotatable with said motor between said motor and said clutch, damper of the damper flywheel shall be provided between the rotor and the flywheel of the motor A power transmission device for a hybrid vehicle. The damper-equipped flywheel includes an engine-side flywheel and a motor-side flywheel, and both are integrally connected by a compression spring and a damping mechanism interposed therebetween. 1. A power transmission device for a hybrid vehicle according to 1.

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