JPH11311136A - Hybrid automobile and driving device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce exhaust emission, and improve heat efficiency by providing with a fuel reformer for reforming hydrocarbon fuel to hydrogen gas, and operating a spark ignition engine with at least either one of hydrocarbon fuel and hydrogen gas. SOLUTION: A part of hydrogen gas generated by a fuel reformer 10 is supplied to a spark ignition engine 1 by a control signal 83, and a hydrogen distributor 14 is controlled so as to supply residual hydrogen gas to a fuel battery 11. An electric power regulator 9 is controlled by a control signal 84 so as to supply electric power of the fuel battery 11 to an electric motor 2. Gasoline is reformed to hydrogen gas by the fuel reformer 10, electric power is generated by the fuel battery 11, and the electric motor 2 is rotated. Rotating force of the electric motor 2 is transmitted to wheels 8 through a differential gear 7 by a power transmitter 6 so as to obtain driving force. Driving force of the wheels 8 is regulated in such a way that an output of a fuel pump 16 is regulated by the control signal 81, and a gasoline flow rate supplied to the fuel reformer 10 is increased/decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hybrid vehicle in which wheels are driven by a spark ignition engine and an electric motor, and a drive device therefor.

[0002]

2. Description of the Related Art FIG. 8 shows a known hybrid vehicle drive unit. This drive device is of a type generally called a parallel hybrid. 8, 1 is a spark ignition engine using gasoline as fuel, 2 is an electric motor, 3 is a storage battery, 4 is a generator, 5 is a clutch, 6 is a power transmission device, 7 is a differential gear, 8 is wheels, and 9 is electric power. It is a regulator. In the figure,
When the required load of the spark ignition engine is relatively small, the clutch 5 is disengaged, power is supplied from the storage battery 3 to the electric motor 2 by the electric power regulator 9, and the wheels 8 are driven by the electric motor 2. On the other hand, in the case of a medium load, power supply from the storage battery 3 to the electric motor 2 is stopped by the power regulator 9, and the clutch 8 is connected to drive the wheels 8 by the spark ignition engine 1. At the same time, the electric power generated by the generator 4 is stored in the storage battery 3. When the load is further high, the driving force of the electric motor 4 driven by the storage battery 3 is added to the driving force of the spark ignition engine 1.

[0003]

By the way, in such a hybrid vehicle, even when the wheels are driven by an electric motor, the electric power is originally turned by a generator by a spark ignition engine using gasoline as fuel, and a storage battery is used. , And the exhaust emission is always emitted regardless of the magnitude of the load.

Further, since the thermal efficiency of the entire spark ignition engine largely depends on the efficiency of the spark ignition engine, it is necessary to operate the spark ignition engine efficiently. However, since the output of a spark ignition engine is generally adjusted by a throttle valve provided upstream of an intake port, the efficiency is greatly reduced due to pumping loss, and it is difficult to increase the thermal efficiency of the entire spark ignition engine.

[0005] It is an object of the present invention to provide a hybrid vehicle having low exhaust emission and high thermal efficiency, and a drive device for the hybrid vehicle.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a spark ignition engine, a driving wheel, a generator generated by the rotational energy of the spark ignition engine or the driving wheel, and storing the power generated by the generator. A hybrid vehicle that includes a storage battery and a motor that is supplied with power from at least one of the storage battery and the generator, and that reforms hydrocarbon fuel into hydrogen gas in a hybrid vehicle driven by the output of the spark ignition engine and the motor. A fuel reformer is provided, wherein the spark ignition engine is solved by operating at least one of hydrocarbon fuel and hydrogen gas.

Another object of the present invention is to provide a fuel reformer for reforming hydrocarbon fuel into hydrogen gas, a fuel cell for generating electric power from the hydrogen gas, and an axle driving motor driven by the electric power of the fuel cell. Controlling a spark ignition engine that uses hydrocarbons and hydrogen gas as fuel, a generator driven by the spark ignition engine, a storage battery that stores the power of the generator, and an amount of power supplied to the motor from the storage battery and the fuel cell. Means for controlling the supply ratio of hydrocarbon fuel to the fuel reformer and the spark ignition engine, and means for controlling the supply ratio of hydrogen gas generated by the fuel reformer to the fuel cell and the spark ignition engine This is solved by a hybrid vehicle drive device having a power transmission means for combining the drive power of the axle drive motor and the drive force of the spark ignition engine and transmitting the drive force to the axle.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a hybrid spark ignition engine for an automobile according to the present invention. In FIG. 1, reference numeral 1 denotes a spark ignition engine using gasoline and hydrogen gas as fuel.

As shown in FIG. 2, the spark ignition engine is provided with a spark plug 43, an intake port 45, and an exhaust port 46 above a combustion chamber 40. Hydrogen gas is supplied into the intake port 45 by the hydrogen supply valve 42, and atomized gasoline is supplied into the cylinder 40 by the injector 41. The piston 44 has a cavity 44
a is provided.

The spark ignition engine does not have a throttle valve, but adjusts the output of the engine according to the amounts of hydrogen and gasoline supplied. By eliminating the throttle valve, pumping loss is eliminated, and high thermal efficiency can be obtained.

When hydrogen gas having good ignitability is used as fuel, air and hydrogen gas are mixed in the intake port 45 to form a homogeneous hydrogen-air mixture in the cylinder 40 and burn.

On the other hand, in the case of gasoline fuel having low ignitability, the fuel is directly injected into the cylinder 40 and the
By suppressing the diffusion of fuel by 4a, a rich mixture is created around the ignition plug 43, and the mixture leaner than the stoichiometric mixture is stably burned.

In FIG. 1, reference numeral 10 denotes a fuel reformer for reforming gasoline to hydrogen gas, and reference numeral 11 denotes a fuel cell for generating electric power from hydrogen gas. Reference numeral 2 denotes an electric motor, and reference numeral 12 denotes a turbo generator that generates electric power by rotating a turbine by the exhaust gas of the spark ignition engine 1, and the generated electric power is stored in the storage battery 3. Reference numeral 6 denotes a power transmission device for synthesizing the shaft output of the electric motor 2 and the shaft output of the spark ignition engine 1.
To the wheels 8 via

Reference numeral 13 denotes a gasoline distributor for changing the supply ratio of gasoline to the fuel reformer 10 and the spark ignition engine 1.
Is a hydrogen distributor that changes the supply ratio of the hydrogen gas generated by the fuel reformer 10 to the fuel cell 11 and the spark ignition engine 1. The distribution ratio of these distributors 13 and 14 is controlled by the control device 15.
Can be arbitrarily changed by the control signals 82 and 83 from.

Reference numeral 9 denotes a power regulator for adjusting the power generated by the fuel cell 11 and the power supplied from the storage battery 3.

FIG. 3 is a diagram showing an operation mode of the power transmission device 6.

FIG. 1A shows a mode used when the spark ignition engine 1 is started. The torque of the electric motor 2 is transmitted to the spark ignition engine 1 to crank the spark ignition engine 1. At this time, no power is transmitted to the differential gear 7.

FIG. 2B shows a mode in which only the driving force of the electric motor 2 is transmitted to the differential gear 7, and the driving force is not transmitted to the differential gear 7 even if the spark ignition engine 1 is rotating.

(C) is a mode in which both driving forces of the spark ignition engine 1 and the electric motor 2 are transmitted to the differential gear 7, and (d).
Is a mode in which only the driving force of the spark ignition engine 1 is transmitted to the differential gear 7. These modes are switched by a control signal 85 from the control device 15 in FIG.

Hereinafter, the operation of the embodiment of FIG. 1 will be described by taking as an example a case where the vehicle is accelerated by increasing the torque with time from the stop state of the spark ignition engine as shown in FIG. In the embodiment of FIG. 1, when the spark ignition engine 1 is started, the gasoline distributor 13 is controlled by the control signal 82 so that the entire amount of gasoline is supplied to the spark ignition engine 1.
The power regulator 9 is controlled by the control signal 84 to supply the electric power of the storage battery 3 to the electric motor 2.

The power transmission device 6 is controlled by a control signal 85 so as to transmit the driving force of the electric motor 2 to the spark ignition engine 1 in the mode shown in FIG.

When the electric power of the storage battery 3 is supplied to the electric motor 2, the electric motor 2 rotates, and the torque is transmitted to the spark ignition engine 1 by the power transmission device 6. The spark ignition engine 1 is cranked and started by this rotational force.

The required torque for the spark ignition engine is the maximum motor torque T1 shown in FIG. 4, that is, the maximum motor torque T2.
Is smaller than the difference between the generated torque ΔT at the lean limit air-fuel ratio when the spark ignition engine 1 is driven by hydrogen gas and the gasoline distributor 13 is controlled by the control signal 82.
0 is controlled so that all gasoline is supplied.

The control signal 83 causes the fuel reformer 1
The hydrogen distributor 14 is controlled so that a part of the hydrogen gas generated by the zero is supplied to the spark ignition engine 1 and the remaining hydrogen gas is supplied to the fuel cell 11. The spark ignition engine 1 at this time
The amount of hydrogen gas supplied to the spark ignition engine 1 is set to be slightly richer than the lean burn limit of the hydrogen-air mixture of the spark ignition engine 1.

Next, the power regulator 9 is controlled by the control signal 84.
Is controlled to supply the electric power of the fuel cell 11 to the electric motor 2. The control signal 85 sets the power transmission device 6 to the mode shown in FIG. 3B, that is, the mode for transmitting only the driving force of the electric motor 2 to the wheels 8.

As a result, the gasoline is reformed into hydrogen gas by the fuel reformer 10, and electric power is generated in the fuel cell 11 by the hydrogen gas, and the electric motor 2 is rotated by the electric power. The rotational force of the electric motor 2 is transmitted to the wheels 8 via the differential gear 7 by the power transmission device 6 to obtain a driving force. Wheel 8
The driving force of the fuel pump 16 is adjusted by the control signal 81.
The output is adjusted by increasing or decreasing the flow rate of gasoline supplied to the fuel reformer 10.

In this operation mode, when the amount of charge of the storage battery 3 detected by the power amount detector 30 is larger than a predetermined threshold, the hydrogen distribution is performed so as not to supply hydrogen to the fuel cell 11. By controlling the heater 14 and controlling the power regulator 9 so as to supply the electric power of the storage battery 3 to the electric motor 2, the electric motor 2 can be turned using the electric power of the storage battery 3 to drive the wheels 8. .

When the torque of the spark ignition engine is T1 shown in FIG.
That is, the motor maximum torque T2 and the generated torque Δ at the lean limit air-fuel ratio when the spark ignition engine 1 is driven by hydrogen gas.
T, the electric power regulator 9 causes the electric motor 2
Is supplied with electric power from the storage battery 3 in addition to the electric power from the fuel cell 11. Thereafter, the power regulator 9 and the fuel pump 16 are controlled so that the gasoline supply amount to the fuel reformer 10 is fixed, and the increased torque is covered by increasing the amount of power supplied from the storage battery 3.

When the load further increases and the torque exceeds the motor maximum torque T2 shown in FIG. 4, the power transmission device 6 is controlled by the control signal 85 in the mode shown in FIG. 3C, that is, in both the motor 2 and the spark ignition engine 1. At the same time as the mode for transmitting the driving force to the wheels 8, the power supply 9 stops the power supply from the storage battery 3 to the electric motor 2. As a result, the generated torque of the electric motor 2 is reduced to T1, the combined torque of the electric motor 2 and the spark ignition engine 1 becomes equal to the electric motor maximum torque T2, and the torque step caused by adding the spark ignition engine 1 to the driving force is reduced. Disappears.

Thereafter, the fuel pump 16 is controlled by the control signal 81 to increase the gasoline supply amount to the fuel reformer 10, and the hydrogen distributor 14 controls the hydrogen gas supply amount to the fuel cell 11 to be constant. Control to increase the torque.

A spark ignition engine 1 and a motor 2 driven by hydrogen gas
FIG. 5 shows the relationship between the total thermal efficiency and the torque according to FIG.

In general, the thermal efficiency of a spark ignition engine is lower than when a fuel cell and an electric motor are combined.

In the present invention, as the torque increases, the load sharing ratio of the electric motor decreases, and the load sharing ratio of the spark ignition engine increases, so that the thermal efficiency decreases. Therefore, in the present invention,
The overall efficiency of the spark ignition engine is the thermal efficiency η of the spark ignition engine alone
When the load on the spark ignition engine becomes higher than the torque T3 equal to 4, the gasoline distributor 13 is controlled so that the entire amount of gasoline is supplied to the spark ignition engine 1, and the power transmission device is operated in the mode shown in FIG. That is, the spark ignition engine 1
Is switched to the mode for transmitting only the driving force of

The gasoline supply amount at this time is controlled by the fuel pump 16 so that the generated torque of the spark ignition engine 1 becomes T3 shown in FIG.

As a result, the wheels 8 are driven only by the spark ignition engine 1. The subsequent increase in torque is covered by controlling the amount of gasoline supplied to the spark ignition engine 1 by the fuel pump 16.

In the above-described embodiment, when the required torque of the spark ignition engine is in the range from T1 to T3, the spark ignition engine 1 uses only hydrogen gas as fuel. It is also possible to use a fuel mixture with gasoline.

That is, the gasoline distributor 13 supplies gasoline to both the fuel reformer 10 and the spark ignition engine 1.
And controls the hydrogen distributor 14 so that hydrogen gas is supplied to both the fuel cell 11 and the spark ignition engine 1. As the required torque increases, the gasoline distributor 1
3, the ratio of gasoline supplied to the spark ignition engine 1 is increased.
%.

As described above, by continuously changing the gasoline ratio, it is possible to prevent the deterioration of drivability due to the torque step when the fuel of the spark ignition engine 1 is switched from hydrogen gas to gasoline.

By mixing highly ignitable hydrogen gas with gasoline, the ignitability during lean burn can be improved.
There is also an advantage that the air-fuel ratio at the lean operation limit can be increased.

In this case, as shown in FIG. 6, when the distribution of the air-fuel mixture is controlled so that the hydrogen-air mixture exists near the ignition plug and the gasoline-air mixture exists outside the ignition plug at the ignition timing, The ignitability can be further improved.

As a method for producing such an air-fuel mixture, the following method can be considered.

A partition plate 50 as shown in FIG. 7 is provided from the hydrogen gas supply unit 42 in the intake port 45 to the vicinity of the intake valve 450. In such a structure, the hydrogen gas supplied into the intake port 45 during the intake stroke is supplied to the cylinder 40 through the flow path 45a above the partition plate 50 of the intake port 45 while mixing with the air. You. On the other hand, air is supplied into the cylinder 40 through the lower channel 45b of the partition plate 50, and atomized gasoline is injected from the injector 41 toward the air. Thus, a hydrogen-air mixture can be generated above the cylinder 40 where the ignition plug 43 is installed, and a gasoline-air mixture can be generated below the cylinder 40.

Table 1 shows typical thermal efficiencies of the components.

[0045]

[Table 1]

When the thermal efficiency of the entire spark ignition engine is evaluated based on the thermal efficiency shown in Table 1, the following is obtained.

(1) In the case where the motor is driven only in the low load region, the total thermal efficiency η = η1, η2, η3 = 0.7 × 0.9 ×
0.9 = 0.567 (2) When driven by a spark ignition engine only in a high load range Total thermal efficiency η = η4 = 0.3 (3) When driven by an electric motor and a spark ignition engine in a medium load range Efficiency 0.3 <η <0.567 (Efficiency fluctuates depending on load) When driven only by a conventional spark ignition engine, the thermal efficiency is 25.
From about 30%, it can be seen that the thermal efficiency can be greatly improved.

[0048]

According to the present invention, in a hybrid vehicle, a fuel reformer for reforming hydrocarbon fuel into hydrogen gas is provided, and the spark ignition engine is operated by at least one of hydrocarbon fuel and hydrogen gas. Can improve the efficiency in the low-load region, and further, in the low-medium-load region, a hybrid that does not emit nitrogen oxides, unburned hydrocarbons, carbon monoxide, and sulfur oxides and has extremely low exhaust emissions Can provide cars.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a hybrid vehicle according to an embodiment of the present invention.

FIG. 2 shows a configuration diagram of the spark ignition engine of FIG.

FIG. 3 shows an operation mode of the power transmission device of FIG.

FIG. 4 is a view showing a torque change for explaining the operation example of FIG. 1;

FIG. 5 is a diagram illustrating a relationship between torque and thermal efficiency in the embodiment of FIG. 1;

FIG. 6 shows an air-fuel mixture distribution in a cylinder of a spark ignition engine for improving ignitability.

FIG. 7 is a configuration diagram of a spark ignition engine according to an embodiment of the present invention.

FIG. 8 shows a configuration diagram of a conventional hybrid spark ignition engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Spark ignition engine, 2 ... Electric motor, 3 ... Storage battery, 6 ... Power transmission device, 8 ... Wheel, 9 ... Power regulator, 10 ... Fuel reformer, 12 ... Turbo generator, 13 ... Gasoline distributor, 14
... hydrogen distributor, 15 ... control device, 30 ... electric energy detector.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuya Shiraishi 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd.

Claims (14)

[Claims] 1. A spark ignition engine, a driving wheel, a generator generated by rotational energy of the spark ignition engine or the driving wheel, a storage battery for storing the power generated by the generator, the storage battery and the power generation An electric motor to which electric power is supplied from at least one of the electric motor and a hybrid vehicle driven by an output of the spark ignition engine and the electric motor, comprising: a fuel reformer for reforming hydrocarbon fuel into hydrogen gas;
A hybrid vehicle, wherein the spark ignition engine is driven by at least one of hydrocarbon fuel and hydrogen gas. 2. The fuel cell system according to claim 1, further comprising: a fuel cell configured to convert hydrogen gas generated by the fuel reformer into electric power, wherein the electric motor includes at least one of the storage battery, the generator, and the fuel cell. A hybrid vehicle, which is supplied with electric power from a hybrid vehicle. 3. The hybrid according to claim 2, wherein in the spark ignition engine, a ratio of supplied hydrocarbon fuel and hydrogen gas is changed according to a driving torque required for the driving wheels. Car. 4. The electric motor according to claim 2, wherein a power supply ratio of the storage battery, the generator, and the fuel cell is changed according to a driving torque required for the driving wheels. Hybrid car. 5. A fuel reformer for reforming hydrocarbon fuel into hydrogen gas, a fuel cell for generating electric power from the hydrogen gas, an axle driving motor driven by electric power of the fuel cell,
A spark ignition engine that uses hydrocarbons and hydrogen gas as fuel, a generator driven by the spark ignition engine, a storage battery that stores the power of the generator, the storage battery, and the storage battery and the fuel cell to an axle drive motor. Means for controlling the amount of electric power to be supplied; means for controlling the supply ratio of hydrocarbon fuel to the fuel reformer and the spark ignition engine; and means for controlling the supply of hydrogen gas generated by the fuel reformer to the fuel cell and the spark ignition engine. A drive device for a hybrid vehicle, comprising: means for controlling a supply ratio; and power transmission means for combining the driving force of an electric motor for driving an axle and a driving force of a spark ignition engine and transmitting it to an axle. 6. A hybrid vehicle according to claim 5, wherein the ratio of the hydrocarbon fuel supplied to the fuel reformer and the spark ignition engine is controlled in accordance with the magnitude of the load on the spark ignition engine. Drive. 7. The drive for a hybrid vehicle according to claim 6, wherein a hydrocarbon supply rate to the spark ignition engine is reduced at a low load, and a hydrocarbon supply rate to the spark ignition engine is increased at a high load. apparatus. 8. The fuel reformer according to claim 5, wherein the ratio of hydrocarbon fuel to be supplied to the fuel reformer and the spark ignition engine according to the magnitude of the load on the spark ignition engine, and to the fuel cell and the spark ignition engine. A drive device for a hybrid vehicle, wherein a ratio of hydrogen gas is controlled. 9. The fuel supply system according to claim 8, wherein at a low load, the hydrocarbon supply rate to the fuel reformer and the hydrogen gas supply rate to the fuel cell are increased, and at a medium load, the hydrocarbon supply rate to the fuel reformer is increased. A drive system for a hybrid vehicle, characterized by increasing the rate of supply of hydrogen gas to a spark ignition engine and increasing the rate of supply of hydrocarbons to the spark ignition engine under high load. 10. A storage device according to claim 5, further comprising means for detecting a remaining amount of electric power stored in the storage battery, and when the remaining power of the storage battery is larger than a predetermined threshold value at a low load, the power of the storage battery is reduced. To drive the axle by supplying it to the axle drive motor, and to drive the axle by supplying hydrocarbon fuel or hydrogen gas to the spark ignition engine when the power of the storage battery is less than the threshold value. A drive device for a hybrid vehicle, comprising: 11. A drive device for a hybrid vehicle, wherein the generator according to claim 5 is a turbo generator that recovers exhaust heat of a spark ignition engine to generate electric power. 12. A hybrid vehicle according to claim 5, wherein the spark ignition engine supplies hydrogen gas into an intake passage and atomizes and injects hydrocarbon fuel into a combustion chamber. Drive device. 13. A spark ignition engine according to claim 12, wherein a mixture of hydrogen and air is distributed so as to surround an electrode circumference of the ignition plug at an ignition timing, and a mixture of hydrocarbon and air is provided outside the hydrogen-air mixture. A drive device for a hybrid vehicle, comprising means for controlling the air-fuel mixture distribution so that the air-fuel ratio is distributed. 14. An air-fuel mixture distribution control means according to claim 13, wherein a partition plate for dividing a port cross section into two air flow paths is provided from near the hydrogen gas supply means in the intake port to near the combustion chamber inlet. A drive device for a hybrid vehicle, comprising: