JP2008213565A - Hybrid vehicle and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce vibration or sound generated when an internal combustion engine is started after traveling is started and to further economize the fuel consumption of a hybrid vehicle. <P>SOLUTION: When a vehicle is started, the supply of fuel to an internal combustion engine is substantially stopped and the internal combustion engine is controlled in such a way that the engine is associated with a motor generator working as an electric motor, so that the engine is accelerated along with the vehicle until a predetermined rpm is reached. After the predetermined rpm has been reached, the supply of fuel to the engine is started. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control method and a control device at the time of start acceleration of a hybrid vehicle. In particular, the present invention relates to a technique for restricting the fuel consumption per total travel distance to be small by restricting or shutting off the fuel supply to the internal combustion engine when the vehicle starts to accelerate. The present invention is an apparatus or method invented for a vehicle that uses a diesel engine as an internal combustion engine, but can be widely implemented in hybrid vehicles that use an internal combustion engine other than a diesel engine.

  Nowadays, hybrid vehicles have been adopted as freight vehicles, bus vehicles, and other business vehicles. Compared to a liquid fuel vehicle, a hybrid vehicle has a complicated device mounted on the vehicle, and thus the vehicle price is unavoidable. Whether or not to adopt a hybrid vehicle for business vehicles, particularly freight vehicles, is given top priority for economic reasons over its lifetime. In particular, evaluation of the fuel consumption of the vehicle is an extremely important factor for the long-term cumulative mileage in which the vehicle is used.

JP 2001-112112 A

  When the inventor of the present application evaluates the fuel consumption per long-distance travel distance in a practical use form of a hybrid vehicle, the dominant factor is the fuel consumption at the start of the vehicle. I focused on that. In other words, in order to make the fuel consumption of a hybrid vehicle long-term economically, it is most reasonable to design so as to limit the flow rate of fuel supplied to the internal combustion engine when the vehicle is accelerated. Especially for delivery vehicles such as courier services, there are frequent modes of starting and accelerating from zero vehicle speed. At this time, the electric power is utilized to the maximum, and the fuel consumed for starting is almost zero. It came to think that it was possible to design so that.

  There is also known a method of controlling the internal combustion engine to start after the vehicle speed approaches a steady speed, such as by stopping the fuel supply to the internal combustion engine when the vehicle starts, such as stopping the rotation of the internal combustion engine. ing. However, in this method, it is necessary to start the internal combustion engine after the start of traveling, and vibration is generated in the vehicle at this time. In particular, when the internal combustion engine is a diesel engine, the occurrence of vibrations when the internal combustion engine is started can hardly be avoided with the current design.

  An object of the present invention is to make fuel consumption of a hybrid vehicle economical. More specifically, an object of the present invention is to provide a hybrid vehicle that can reduce the amount of fuel supplied to the internal combustion engine at the time of starting acceleration as much as possible. The present invention is particularly suitable for use in a hybrid vehicle having an internal combustion engine as a diesel engine. The fuel consumption of the internal combustion engine is extremely reduced at the time of starting acceleration, and the vibration of the vehicle due to the start of the internal combustion engine is avoided. It is an object of the present invention to provide an apparatus that can do this.

A first aspect of the present invention is a hybrid vehicle, in which a rotary shaft of a motor generator is connected to an output shaft of an internal combustion engine via a clutch.
A means for controlling the clutch to a contact state as the vehicle starts to be accelerated and setting and controlling the motor generator in a motor mode, and supplying the internal combustion engine until the rotational speed of the internal combustion engine by the start acceleration reaches a predetermined value. And a means for controlling the fuel supply amount to be equal to or less than the value at the time of idling (Claim 1).

  The present invention can be implemented in a vehicle in which the internal combustion engine is a diesel engine, and it is effective, and the means for controlling the value below the idling value includes means for cutting off the fuel supply. Can do.

  The second aspect of the present invention is a control method invention, which is a control method at the time of starting acceleration of a hybrid vehicle in which an output shaft of an internal combustion engine drives an input shaft of a motor generator and a transmission via a clutch, When starting the vehicle, the motor generator is controlled to the motor mode to start the vehicle, and when the rotational speed of the internal combustion engine becomes correspondingly equal to the rotational speed of the motor generator, the clutch is controlled to contact. Thereafter, the internal combustion engine is rotated by the rotation of the motor generator until the vehicle is accelerated to a suitable vehicle speed, and the fuel supply to the internal combustion engine is stopped or restricted (claim 2).

  In this control method, after the internal combustion engine is started in a stopped state, the clutch is automatically controlled to be disengaged to keep the internal combustion engine in an idling state, and the clutch is automatically controlled to be in contact when starting. The supply can be controlled to be cut off or restricted (Claim 3). Such control is executed when the temperature of the internal combustion engine is low, particularly in a diesel engine, since it is desirable to lengthen the idling period after starting.

  The present invention controls the rotation of the internal combustion engine along with the acceleration of the vehicle in a state where the fuel supply to the internal combustion engine is substantially stopped at the time of start acceleration of the hybrid vehicle. Fuel supply to the already rotating internal combustion engine is started at an appropriate timing at which the start acceleration of the vehicle is almost finished. As a result, most of the energy required for starting acceleration is supplied from the electric motor, and the braking energy recovered as electric energy during traveling or braking is used for starting acceleration almost maximally. . The internal combustion engine's rotating shaft is not connected to the drive system after the acceleration is completed, but is connected to the drive system from the beginning of acceleration, and the internal combustion engine is rotated with little or no fuel supplied. The mechanical vibration that occurs when the engine is started is virtually eliminated. The internal combustion engine that is driven is an extra load for the motor that accelerates the vehicle, but this is designed to be smaller or smaller than the energy supplied from the motor to the axle for the vehicle to start and accelerate. Can do.

  The present invention utilizes the characteristics that the performance of a battery has been improved in recent years, and the charging capacity of an in-vehicle battery is increased with respect to its volume and weight. By practicing the present invention, the economy related to fuel consumption per mileage of the hybrid vehicle is further improved, and a device free from vibration and sound associated with the start of the internal combustion engine delayed at the time of starting is obtained. When the internal combustion engine is a diesel engine, the vibration and sound generated when the internal combustion engine is started are relatively large.

  The apparatus and control method of the present invention are further useful in the near future when the hybrid vehicle battery mounted on the vehicle is improved and the charge capacity per weight, the charge capacity per volume, and the battery price for the charge capacity are reduced. It is thought to become.

(Example)
The present invention will be described in more detail using specific examples. First, the main structural part of a hybrid vehicle that implements the present invention will be described. FIG. 1 is a block diagram illustrating a power system of a hybrid vehicle according to an embodiment of the present invention. The output shaft of the internal combustion engine 1 is connected to the input shaft of the transmission 3 via the clutch unit 2, and the output shaft of the transmission 3 is connected to the input shaft of the differential gear 4. The output shaft of the differential gear 4 is connected to the drive shafts of the wheels 5 on both sides. The internal combustion engine 1 is provided with a starter 9.

  Here, in the clutch unit 2, a clutch 6 whose input shaft is connected to the output shaft of the internal combustion engine, a motor generator 7 connected to the output shaft of the clutch 6, and a hydraulic pressure for controlling the opening and closing of the clutch 6. A drive system is provided. Since the hydraulic drive system of the clutch 6 has a well-known structure and the drawing becomes complicated, the illustration is omitted here. This motor generator 7 is in the form of a synchronous rotating machine corresponding to three-phase alternating current. The motor generator 7 includes a rotor 7 a that is fixed to the output shaft of the clutch 6 and rotates, and a stator 7 b that is fixedly attached to the inside of the frame of the clutch unit 2.

  In the motor generator 7, the rotor 7a mechanically rotates in synchronization with a rotating magnetic field generated around the axis of the rotating shaft by a three-phase alternating current supplied to the stator 7b. As is well known, when the phase rotation speed of the field generated by the three-phase alternating current supplied to the winding of the stator 7b is larger than the mechanical rotation speed of the rotor 7a, this structure is well known. The motor generator 7 acts as an electric motor. When the phase rotation speed of the field generated by the three-phase alternating current supplied to the winding of the stator 7b is smaller than the mechanical rotation speed of the rotor 7a, the motor generator 7 acts as a generator. When the phase rotation speed generated by the current supplied to the stator 7b is equal to the mechanical rotation speed of the rotor 7a, the motor generator 7 is in a substantially idling state where neither load nor driving force is generated.

  This stator winding is connected to the three-phase AC terminal of the inverter 11. A hybrid battery 12 is connected to the DC terminal of the inverter 11. The control system of the inverter 11 is connected to the hybrid control circuit 13 and the engine control circuit 14 by a control network (CAN). The engine control circuit 14 controls the fuel injection amount according to the rotation of the internal combustion engine 1. The transmission 3 is controlled by a transmission control circuit 15.

  In this apparatus, the output of the internal combustion engine 1 drives the input shaft of the transmission 3 via the clutch 6, and the rotor of the motor generator 7 is connected to the output shaft of the clutch 6. The rotation information of the input shaft and the output shaft of the transmission 3 is taken into the transmission control circuit 15 respectively. Therefore, the hybrid control circuit 13 drives and accelerates the rotation of the rotor of the motor generator 7 according to the phase of the three-phase AC supplied to the stator winding 7b of the motor generator 7 controlled by the inverter 11, or It can be controlled to decelerate by braking. When the motor generator 7 acts as an electric motor, the electric energy supplied from the battery 12 is converted into a three-phase alternating current by the inverter 11 and rotationally accelerates the armature of the motor generator 7. When the motor generator 7 acts as a generator, the rotation of the rotor of the motor generator 7 driven by the input shaft of the transmission 3 is in a braking state. A phase alternating current is generated and converted to a direct current through the inverter 11 to charge the battery 12.

Here, as described above, the object of the present invention is to further reduce the fuel consumption of this hybrid vehicle. In particular, the fuel to be supplied to the internal combustion engine 1 when accelerating from when the vehicle speed is zero or very low is to be reduced. FIG. 2 is a diagram for explaining the operation of the apparatus according to the present invention. The time is plotted on the horizontal axis, and the rotational speed, internal combustion engine state, control mode, and clutch state are plotted on the vertical axis. Referring to FIG. 2, the internal combustion engine 1 at time t ₀ is in the idling state, the clutch 6 is in a state of "OFF". The vehicle is stationary. This is, for example, a state of warming up after the internal combustion engine is started.

Starting operation of the vehicle begins when the driver sets the starting gear in the transmission 3, the driver at time t ₁ is started stepping on the accelerator pedal. At this time, the vehicle speed is zero, and the current supplied from the battery 12 is converted into an alternating current via the inverter 11 and supplied to the motor generator 7 operating in the motor mode. The vehicle starts running. Rotational speed of the electric generator 7 equals the rotation speed of the internal combustion engine 1 at time t _2. At this time, the clutch control means (also serving as a transmission control circuit) controls the clutch 6 to be in the engaged state. At the same time, the engine control circuit 14 cuts off the fuel supplied to the internal combustion engine 1 and controls the flow rate to be substantially reduced to zero. Thereafter, the motor generator 7 in the motor mode increases the rotational speed in accordance with the driver's operation of the accelerator pedal.

As shown in FIG. 2, the engine control circuit 14 supplies fuel to the internal combustion engine 1 when the vehicle speed of the vehicle accelerated by the motor generator 7 at time t ₃ reaches a preset vehicle speed X km / h. To start. Later from time t _3, the fuel is supplied to the internal combustion engine 1 in accordance with the depression amount of the accelerator pedal that is operated by the driver, a running condition of the well-known conventional hybrid vehicle.

  As described above, the fuel supply is cut off (or almost cut off) from the idling state until the vehicle speed reaches X km / h. Since the fuel supply is cut off, the internal combustion engine 1 is forcibly rotated by the motor generator 7, that is, it is rotated. By operating the apparatus in this way, a part of the output load of the motor generator 7 is used to accelerate the rotation of the internal combustion engine 1, but until the vehicle speed reaches Xkm / h, the internal combustion engine No vibration at the start of 1 occurs. At the same time, since the fuel supply to the internal combustion engine 1 is stopped or almost stopped until the vehicle speed reaches X km / h, the acceleration during this time uses the electrical energy accumulated during the previous stop or deceleration.

  FIG. 3 is a flowchart for explaining the control at the start of the apparatus according to the present invention. In the apparatus and the control method of the present invention, the energy required for starting the vehicle is supplied not by the internal combustion engine 1 but by electric energy from when the vehicle speed is zero or very low to when the vehicle is accelerated. At this time, the rotating shaft of the internal combustion engine 1 rotates with the motor generator 7 via the clutch 6, and the internal combustion engine 1 rotates with the rotating shaft of the motor generator 7 and the input shaft of the transmission 3 to act as an electric motor. It becomes the load of the generator 7. Accordingly, at this time, the transmission control circuit 15 is controlled not according to the characteristics of the internal combustion engine 1 but according to the characteristics of the motor generator 7 acting as an electric motor. More specifically, the control is performed according to the characteristics of the state in which the rotating system of the internal combustion engine 1 substantially not supplied with fuel is connected as a load. When the vehicle is accelerated and reaches an appropriate vehicle speed, fuel is supplied to the internal combustion engine 1 under the control of the engine control circuit 14. At this time, the motor generator 7 acting as an electric motor has an auxiliary role, and the vehicle is further accelerated by the output of the internal combustion engine 1.

  According to the apparatus and method of the present invention, most of the energy required for starting the vehicle is supplied as electric energy, so that the fuel consumption per total travel distance can be greatly improved. The apparatus or the control method according to the present invention is considered to be extremely effective in a form using a next-generation hybrid battery having a large electric capacity per volume.

The block block diagram explaining the structure of this invention Example apparatus. The main part operation | movement time chart of this invention Example apparatus. The principal part control flowchart of this invention Example apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Clutch unit 3 Transmission 4 Differential gear 5 Wheel 6 Clutch 7 Motor generator 7a Rotor 7b Stator 9 Starter 11 Inverter 12 Battery 13 Hybrid control circuit 14 Engine control circuit 15 Transmission control circuit

Claims (3)

In a hybrid vehicle in which a rotating shaft of a motor generator is connected to an internal combustion engine output shaft via a clutch,
A means for controlling the clutch to a contact state as the vehicle starts to be accelerated and setting and controlling the motor generator in a motor mode, and supplying the internal combustion engine until the rotational speed of the internal combustion engine by the start acceleration reaches a predetermined value. A hybrid vehicle comprising: means for controlling a fuel supply amount to be equal to or less than a value at idling. A control method at the time of start acceleration of a hybrid vehicle in which an output shaft of an internal combustion engine is connected to a motor generator via a clutch,
At the start of starting the vehicle, the motor generator is controlled to a motor mode to start the vehicle, and when the rotational speed of the internal combustion engine becomes substantially equal to the rotational speed of the motor generator, the clutch is controlled to contact, Thereafter, the internal combustion engine is rotated until the vehicle is accelerated to a suitable vehicle speed, and the fuel supply to the internal combustion engine is stopped or restricted.   The method for controlling a hybrid vehicle according to claim 2, wherein after the internal combustion engine is started in a stopped state, the clutch is disengaged to keep the internal combustion engine in an idling state.

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