JPH1081147A - Hybrid electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the use of a smaller engine in a hybrid electric automobile and thus save energy and suppress exhaust pollution by reducing the size, weight and costs of a hybrid power train driven by means of an engine and also a motor. SOLUTION: A hybrid electric automobile drives its wheels 8 and 9 by means of an engine 100 which uses fossil fuel as the power source and also a motor 300 which uses a battery 600 as the power source. The output shaft of the engine 100 is connected through a clutch 200 to one input shaft 801 of a three- shaft coupler 800 of a type with two-shaft input and single-shaft output, the output shaft of the motor 300 is connected through a speed reducer 1200 to the other input shaft 802 of the three-shaft coupler 800, and the output shaft 803 of the three-shaft coupler 800 is connected through universal joints 900a and 900b and power transmission shafts 901 and 902 to the input shaft of a differential gear 700 of which output shaft is connected to the wheels 8 and 9, to thereby form an engine-drive system power train and a motor-drive system power train.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power train of a hybrid electric vehicle in which wheels are driven by an engine powered by fossil fuel and an electric motor powered by a battery.

[0002]

2. Description of the Related Art FIG. 5 shows a power train of a known hybrid electric vehicle, which is a system generally called a parallel type hybrid. In the figure, 1 is an engine,
Reference numeral 2 denotes a clutch, 3 denotes an electric motor, 4 denotes a transmission, 5 denotes a motor driving power converter, 6 denotes a battery, 7 denotes a differential gear, 8 denotes a right wheel, and 9 denotes a left wheel.

In FIG. 1, when the engine is driven, the operation of the power converter 5 is stopped to stop the power supply from the battery 6, and the vehicle is driven by the power of the engine 1 by connecting the clutch 2. In the case of electric motor drive (battery drive), the clutch 2 is disengaged, the engine 1 is stopped, the electric power converter 5 is operated, and the electric motor 3 drives the vehicle.

FIG. 6 shows a power train of another known hybrid electric vehicle, which is a system generally called a series hybrid. 5, the same components as those in FIG. 5 are denoted by the same reference numerals.

In FIG. 6, 10 is a generator, 11 is a rectifier, and 12 is a speed reducer. In this system, the variable speed drive is performed by the electric motor 3, so the transmission 4 shown in FIG. In the case of driving the engine by this system, the engine 1 is driven, and the electric motor 3 is driven via the power converter 5 by the DC power generated by the generator 10 and the rectifier 11. In the case of motor drive, the engine 1 is stopped, the power generation by the rectifier 11 is stopped, and the motor 3 is driven by the power from the battery 6 via the power converter 5.

Here, the difference between FIG. 5 and FIG. 6 will be described.
In the system shown in FIG. 5, the power supply from the power converter 5 is stopped when the engine is driven, and the power from the engine 1 is stopped when the motor is driven. That is, the parallel hybrid of FIG. 5 has a parallel configuration of two independent power trains that can operate in the entire operation range (acceleration / deceleration, high-speed running, etc.) of the vehicle. On the other hand, in the series-type hybrid shown in FIG. 6, even when the engine is driven, all the electric systems except the battery 6 operate in addition to the mechanical system. That is, the power train has a mechanical system and an electric system configured in series.

[0007]

In the parallel type hybrid system shown in FIG. 5, the power train requires a maximum output capacity required for acceleration, whether the engine is driven or the motor is driven. In other words, the system has two power trains having the maximum output.
This is a serious problem for a hybrid electric vehicle because power train equipment is expensive and bulky and heavy, and has not been practically used in practice.

On the other hand, in the series type hybrid system shown in FIG. 6, since the power converter and the motor are used for both the engine drive and the motor drive, the price, size and weight are reduced as compared with the system shown in FIG. However, even in this method, all devices need to have the maximum output capacity. In particular, since two power sources, an engine having the maximum output capacity and a battery having the maximum output capacity, are required, the price, size, and weight are increased as compared with a general battery-powered electric vehicle.

A hybrid electric vehicle having an engine and an electric motor (battery) has the same running performance as an engine vehicle using only an engine as a power source, and has a chargeable traveling distance that is equal to that of a normal battery-driven electric vehicle. Since the restrictions are eliminated, the driving performance is significantly improved as compared with a normal battery-powered electric vehicle. However, as described above, the known hybrid electric vehicles have significant problems in the price, size, and weight of the power train, and further improvement is required for widespread use.

Accordingly, the present invention provides a hybrid electric vehicle which is capable of reducing the price, size, and simplification of a power train, further conserving energy and reducing exhaust pollution, and which can be applied to a low floor bus. It is something to offer.

[0011]

The maximum output of the power train required for running the vehicle is the output required from the acceleration performance. On the other hand, the output required when traveling at a constant speed in a city
It is a fraction of the maximum output. 7A and 7B are diagrams showing the running characteristics of the engine vehicle, wherein FIG. 7A shows the torque-vehicle speed characteristics when the accelerator is fully opened, and FIG. 7B shows the running resistance of the vehicle on a flat road. Starting at full throttle, it accelerated, operation of the vehicle when the balanced running at a speed V ₁ was made as an arrow indicated by a broken line (c) in FIG.

[0012] When traveling at a speed V ₁ was squeezed accelerator near speed V _1, to balance the running at the operating point A. The torque-vehicle speed characteristic of balanced traveling at the operating point A is as shown in (d), and the output of the engine having this characteristic is a fraction of that when the accelerator is fully opened. The speed V ₁ was, it is generally a speed corresponding to the speed during urban driving.

The present invention has been made in view of the fact that the engine output during the above-mentioned urban driving need only be a fraction of the maximum output required at the time of acceleration. An engine drive unit is constructed by integrating the engine that has a fraction of the maximum output to be integrated with the clutch,
The output shaft is connected to one input shaft of a three-axis coupling machine having two axes and one axis. Further, an electric motor and a speed reducer are integrally formed to constitute an electric motor drive (battery drive) unit, and an output shaft thereof is connected to the other input shaft of the three-shaft coupler. The electric motor is driven by a battery via a power converter.

The electric vehicle of the present invention has a hybrid power train system including an engine drive system and a motor drive system. The motor drive system has a maximum output required for acceleration, and the engine output is regulated. Make the output necessary for constant speed running at a speed higher than the speed. During acceleration, it is driven only by the motor drive system, and when traveling at a constant speed after acceleration, it runs only with the engine drive system. That is, only the electric motor drive is used during acceleration and deceleration except when traveling at a constant speed. When the engine is not driven, the clutch is disengaged to disconnect the engine from the wheel drive system.

According to the present invention, the vehicle is driven at a normal vehicle performance at the time of starting the vehicle and at the time of acceleration, since the motor is driven by the motor drive system having the same capacity as the maximum output of the engine of the engine vehicle. Further, since the engine has the power required for constant speed running at a speed higher than the specified speed, the same performance as that of the engine vehicle can be obtained even at a constant speed running at a speed higher than the specified speed. If an output higher than the engine output is required when accelerating at a high speed or climbing a hill at a speed higher than a specified speed, the motor drive system power train is operated to provide torque assist.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of this embodiment, and the same components as those in FIGS. 5 and 6 are denoted by the same reference numerals. In FIG. 1, reference numeral 100 denotes an engine, and 200 denotes a clutch. These constitute an engine drive unit 101 having an integral structure. On the other hand, reference numeral 300 denotes an electric motor, and 1200 denotes a speed reducer. These constitute an electric motor drive unit 301 having an integral structure. The electric motor 300 is connected to an electric motor driving power converter 500 using a battery 600 as a power source.

Reference numeral 800 denotes a three-axis coupling machine having two axes and one axis output. One input shaft 801 is connected to the output shaft of the clutch 200, and the other input shaft 802 is connected to the output shaft of the speed reducer 1200. I have. Output shaft 803 of three-axis coupling machine 800
Are connected to the input shaft of the differential gear 700 via universal joints 900a and 900b and power transmission shafts 901 and 902. The input shafts 801 and 802 of the three-shaft coupler 800 and the output shaft of the differential gear 700 are arranged in parallel.

This embodiment is a power train which is substantially the parallel hybrid type shown in FIG. 5 and does not have the transmission 4, and both right and left wheels 8, 9 are driven by power trains of an engine drive system and a motor drive system. System. Here, the engine drive system power train means the engine 100 and the clutch 200 (engine drive unit 101), the three-axis coupling machine 800, the universal joints 900a and 900b, the power transmission shafts 901 and 902, the differential gear 700, the wheel drive shaft, and the wheels. 8 and 9; the motor drive system power train is a battery 600;
Power converter 500, electric motor 300, and reduction gear 1200
(Electric motor drive unit 301) Refers to a system including a three-axis coupling machine 800, universal joints 900a and 900b, power transmission shafts 901 and 902, a differential gear 700, a wheel drive shaft, and wheels 8 and 9. Note that the engine output is an output required for constant speed running at or above the specified speed (generally,
About 1/5 of the maximum output).

It is assumed that the motor drive system has a maximum output required for acceleration. When the vehicle is stopped, the engine 100 is stopped. However, when the engine idling operation is performed when the vehicle is stopped, the clutch 200 is disengaged.

In this embodiment, the motor is driven by a motor drive system at the time of starting and accelerating. When the speed exceeds the reference speed in the high-speed range, the clutch 200 is engaged, and the operating engine 1
00 and the electric motor 300 are connected. Switching between the engine drive system and the motor drive system is performed by a torque switching control device (not shown), and the switching is performed so that the fluctuation of the driving force is reduced as much as possible.

FIG. 2 is a diagram showing the output sharing of the power train between the engine drive system and the motor drive system of this embodiment. In the figure, (a) shows the torque-vehicle speed characteristic of the motor drive system power train, and (b) shows the torque-vehicle speed characteristic of the engine drive system power train. (C) shows the running resistance at the time of running on a flat road as a torque-vehicle speed characteristic.

[0022] In this embodiment, the maximum output characteristic as shown in FIG imparted to the motor drive system, an engine drive system is adapted torque is generated in the high speed range than the vehicle speed V _0. This characteristic corresponds to a torque-vehicle speed characteristic in which the shift lever is shifted to the highest speed in an engine vehicle.

Next, the operation of the power train according to the present embodiment when the vehicle starts running at a constant speed after starting and accelerating after stopping will be described with reference to FIG. FIG. 3 shows the output torque of the motor drive system power train, the output torque of the engine drive system power train, and the vehicle speed with respect to the time after the start, and (a), (b), and (c) respectively correspond. .

When the accelerator is depressed, FIG.
Generates a torque corresponding to. Torque of FIG. 2 (a) - accelerated according the vehicle speed characteristics, it accelerates until time T ₁ as shown in the (a) FIG. When the driver approaches the target vehicle speed (V _{1 in} FIG. 2), the driver returns the accelerator, so that the torque decreases, and at time T ₂ , the torque matches the running resistance of the target speed.
Thereafter, the power train is switched from the motor drive system power train to the engine drive system power train.

In the torque switching, the engine torque is transmitted to the wheel drive shaft by connecting the clutch 200, and the torque from the motor drive system is reduced. Although the torque switching is not described in detail here, the torque switching control device reduces the generated torque of the motor drive system power train by an amount corresponding to the transmission torque from the clutch 200.

FIG. 4 shows an embodiment in which the power train of FIG. 1 is applied to a vehicle. The same components as those in FIG. 1 are indicated by the same numbers. In FIG. 4, reference numeral 1000 denotes a vehicle body, and 1001 denotes a floor of the vehicle body. In this embodiment, the engine drive unit 101 and the motor drive unit 301 having the integrated structure described above are connected to the vehicle body 1.
000, and is a system for driving the vehicle by rear wheels.

Battery 600 is mounted under the floor at the center of vehicle body 1000. For vehicles such as electric buses, it is desirable to have as many seats as possible on low floors,
Battery 600 is arranged under the vehicle floor between the front wheels and the rear wheels. Further, in a vehicle such as an electric bus, a space for installing a drive system is provided in a rear portion of the vehicle more than in a front portion of the vehicle having a driver's cab.

Although the present invention is directed to an electric vehicle provided with both an engine drive system and an electric motor drive system power train, it is possible to operate the entire operation range only by the electric motor drive system power train.

[0029]

As described above, the present invention is a parallel hybrid system of an engine drive system and an electric motor drive system, and the engine capacity is a fraction of the maximum capacity required for acceleration. Since the power train is unnecessary, the following effects can be obtained. (1) Because a small engine can be used, 1) The engine price can be significantly reduced. 2) Energy saving is improved. 3) Emission pollution is reduced. (2) The price of the power train can be reduced. (3) If the engine drive unit and the electric motor drive unit are arranged as a unitary structure at the rear of the vehicle body and the battery is disposed under the floor of the vehicle body, the effect of applying the invention to a hybrid electric bus such as a low floor electric bus is great.

[Brief description of the drawings]

FIG. 1 is a diagram showing a power train of a hybrid electric vehicle as an embodiment of the present invention.

FIG. 2 is a diagram showing power sharing in FIG. 1;

FIG. 3 is an operation explanatory diagram of FIG. 1;

FIG. 4 is a diagram showing an embodiment in which the power train of FIG. 1 is applied to a vehicle.

FIG. 5 is a diagram showing a power train of a known parallel hybrid electric vehicle.

FIG. 6 is a diagram showing a power train of a known series-type hybrid electric vehicle.

FIG. 7 is a diagram showing running characteristics of an engine vehicle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,100 Engine 2,200 Clutch 3,300 Electric motor 4 Transmission 5,500 Power converter 6,600 Battery 7,700 Differential gear 8 Right wheel 9 Left wheel 10 Generator 11 Rectifier 12,1200 Reduction gear 101 Engine drive unit 301 Motor drive unit 800 3-axis coupler 801 802 Input shaft 803 Output shaft 900a, 900b Universal joint 901 902 Power transmission shaft 1000 Body 1001 Body floor

Claims (9)

[Claims] 1. A hybrid electric vehicle in which wheels are driven by an engine using a fossil fuel as a power source and an electric motor using a battery as a power source. An output shaft of the electric motor is connected to the other input shaft of the three-axis coupling device via a speed reducer, and an output shaft of the three-axis coupling device is connected to a universal joint and A hybrid electric vehicle in which an engine drive system power train and an electric motor drive system power train are formed by connecting an input shaft of a differential gear via a power transmission shaft and an output shaft of the differential gear to wheels. 2. The hybrid electric vehicle according to claim 1, wherein the engine and the clutch are integrated. 3. The hybrid electric vehicle according to claim 1, wherein the electric motor and the speed reducer have an integral structure. 4. The hybrid electric vehicle according to claim 1, wherein the drive wheels connected to the output shaft of the differential gear are rear wheels. 5. The hybrid electric vehicle according to claim 1, wherein the battery is mounted under a vehicle body floor between a front wheel and a rear wheel. 6. The hybrid electric vehicle according to claim 1, wherein the input shaft of the three-shaft coupler and the output shaft of the differential gear are arranged in parallel. 7. The hybrid electric vehicle according to claim 1, wherein the engine has a capacity necessary for the vehicle to travel on a flat road at a speed equal to or higher than a specified value. A hybrid electric vehicle characterized in that the capacity of the hybrid electric vehicle is a capacity necessary for accelerating and decelerating the vehicle. 8. The method of claim 1, 2, 3, 4, 5, 6, or 7.
The hybrid electric vehicle according to claim 1, wherein the motor drive system power train is operated when the vehicle accelerates, decelerates, and operates at a speed lower than a specified value, and the engine drive system power train is operated at a speed higher than the specified value. Electric car. 9. The hybrid electric vehicle according to claim 1, wherein when an engine output is insufficient in an operation state by an engine drive system power train, the electric power of the motor drive system is reduced. A hybrid electric vehicle that operates a train to assist torque.