JP2007168719A - Hybrid automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for increasing regenerative energy by hybrid by providing and rationally controlling a chargeable state of a hybrid battery, and carrying out effective regenerative braking by minimizing energy loss by auxiliary braking, in a conventional large hybrid automobile, wherein regenerative braking for charging the hybrid battery and exhaust braking for blocking an exhaust passage are both used in deceleration or in descending a slope, while they are uniformly controlled irrespective of whether there is a charging capacity in the hybrid battery, or not. <P>SOLUTION: An auxiliary braking operation end operated by a driver is commonly used in both the exhaust braking and hybrid braking. When the operation end is operated into a braking state, a control system observes a charging capacity of the hybrid battery to control such that the exhaust braking is prohibited, and the regenerative braking is given priority when there is a charging capacity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an auxiliary braking device for a hybrid vehicle that uses both internal combustion engine power and electric power. The present invention controls exhaust braking to obtain a braking force by partially closing an exhaust passage of an internal combustion engine among auxiliary braking used for deceleration during traveling or traveling on a downhill, and control of an electric rotating machine in a power generation mode. Thus, the present invention relates to combined control with regenerative braking that converts running energy into electric energy and regenerates generated electric power in a battery. The present invention relates to simplification of driving operation and effective use of energy generated by braking.

  The hybrid vehicle is equipped with an internal combustion engine, a generator, and an electric motor that can connect the rotation shaft to the axle. When driving and accelerating the vehicle, the driving force generated by the electric motor can be supplementarily used together with the power generated by the internal combustion engine. When the vehicle is in a braking state, braking by the internal combustion engine (engine brake) and braking by the generator (electric brake) can be used simultaneously. When braking by the generator is performed, the electric energy generated by the generator is regeneratively charged to the battery, and when the vehicle accelerates, the electric energy is taken out from the battery and the electric motor is driven, The energy generated by braking can be used effectively. In addition, a configuration in which a generator and an electric motor are mounted on a vehicle as one piece of hardware, that is, a motor generator, and used as a generator (ie, a braking device) or an electric motor (ie, an acceleration device) according to the operation mode is also widely known. . The hybrid vehicle manufactured and sold by the applicant of the present application is basically in this form.

  Braking by an internal combustion engine (so-called engine brake) can be set by opening the accelerator pedal or shifting down the transmission. In a medium-sized or large-sized vehicle, an on-off valve is further provided in the exhaust passage of the internal combustion engine, and the operation of the on-off valve is controlled to be closed to enhance the braking effect by the internal combustion engine. In a medium-sized or large vehicle manufactured and sold by the applicant of the present application, an operation lever for auxiliary braking is provided below the driver's seat steering wheel, and the driver operates the operation lever to open and close the exhaust passage. The valve can be controlled to open and close. Furthermore, in a hybrid vehicle manufactured and sold by the applicant, a motor generator that is driven by being linked to the axle is operated by operating the operating lever in a braking state, that is, by closing the exhaust passage opening / closing valve. It acts as a generator, and the current generated from the motor generator is converted into a direct current and regeneratively supplied to the hybrid battery as a charging current. When the hybrid battery is fully charged, this charging current is cut off, or this charging current is connected to a separately provided resistor and dissipated.

Japanese Patent No. 3163349 (Hino Motors) Ogoshi, Miyazaki et al. “Development of lead-acid battery status detection technology” Shin-Kobe Technical Report No.14, December 2004, pp. 7-12

  As described above, in the structure of the conventional example, when the operation lever for auxiliary braking is operated to the braking state, the opening / closing valve of the exhaust passage is controlled to the closed state, and simultaneously, the power generation mode of the motor generator of the hybrid vehicle (or Generator) is set to valid. This is configured so that the on-off valve of the exhaust passage is controlled to be closed in conjunction with the operation of the operation lever regardless of the amount of electricity charged in the hybrid battery. This is because there is a charge margin when the charge amount of the hybrid battery is small, and part of the energy that can be generated and regenerated and charged in the power generation mode of the hybrid vehicle is blocked by the exhaust passage being blocked. It is lost as heat generated from the internal combustion engine as a so-called engine brake.

  An object of the present invention is to provide a device that can further reduce the energy lost from the internal combustion engine due to the blockage of the exhaust passage and can effectively regenerate it. An object of the present invention is to provide a device that can regenerate energy generated by braking as effectively as possible when exhaust braking or regenerative braking is operated by a driving operation. The present invention effectively reduces regenerative braking effectively by minimizing the energy lost by auxiliary braking while keeping the number of operation ends operated by the driver as one, without increasing the number of auxiliary braking operation ends. An object is to provide an apparatus that can be used. An object of the present invention is to further increase the fuel efficiency (travelable distance per unit fuel capacity, for example, kilometers / liter) of a hybrid vehicle.

  Here, there is known means for controlling the charging current to be automatically limited or cut off when the charging capacity of the hybrid battery approaches a maximum rating. However, the configuration and control of the present invention are not limited thereto. Is different. This control for automatically limiting or cutting off the charging current is one of safety controls for preventing the hybrid battery from being overcharged. At this time, the hybrid battery has no charge margin and is regenerated. Since it is impossible in principle, it is unavoidable that some energy generated by braking is lost.

  The present invention does not simply connect regenerative braking and control of the control valve for closing the exhaust passage in parallel to the signal of the operation end of the auxiliary brake operated by the driver, but instead of the control signal of the auxiliary brake operation end. The hybrid control system is preferentially incorporated, the regenerative braking is executed as much as possible by the hybrid control system, and the exhaust brake is effectively controlled only for the braking exceeding the capacity of the regenerative braking.

That is, the present invention employs both regenerative braking means (charging the battery with a current generated from a generator driven by the rotation of the axle) and exhaust braking means (partly closing the exhaust passage of the internal combustion engine) as auxiliary braking means. In the hybrid vehicle provided, an auxiliary braking operation end operated by the driver during the traveling is provided in common for regenerative braking and exhaust braking, and when the auxiliary braking is input from the operation end, the main battery measured at that time (A) Only for regenerative braking,
(B) Combined use of regenerative braking and exhaust braking,
(C) Exhaust braking only
Control means (using an electronic circuit) for enabling auxiliary braking preferentially in this order is provided.

  (B) When changing from the combined use of regenerative braking and exhaust braking to (c) exhaust braking only, the system includes a means for switching to another mode and then changing to (c) exhaust braking only. It can be.

  The present invention includes an internal combustion engine that drives an axle, and an exhaust braking means that decelerates the vehicle by partially closing an exhaust passage of the internal combustion engine, and further applies an auxiliary driving force and an auxiliary braking force to the vehicle, respectively. An electric motor and a generator; a battery mounted on the vehicle; a charging state monitoring means for monitoring a charging state of the battery; a driving mode for supplying a driving current from the battery to the electric motor; or a current generated by the generator In a hybrid vehicle provided with hybrid control means for setting and controlling each of the braking modes to be supplied to the battery as a charging current, the operation of the exhaust braking means and the activation of the braking mode are operated by a driver as one operation An auxiliary braking operation end controlled by the end is provided, and when the auxiliary braking operation end is operated in a braking state while the vehicle is running And a control means for giving priority to the braking force generated by the generator over the braking force generated by the exhaust braking means when the battery is in a chargeable state according to the output of the battery charge state monitoring means. It is characterized by.

  The electric motor and the generator include a rotating machine as one piece of hardware as a motor generator and a control circuit for supplying current to the winding of the rotating machine, and the electric motor or the electric generator is controlled according to a control mode of the control circuit. It can be set as the structure provided with the control means made to act as a generator.

  The auxiliary braking operation end may be configured to include means for controlling the braking force generated by the auxiliary braking stepwise or continuously.

  According to the present invention, when the battery for hybrid driving has a charge margin, even if the driver operates the auxiliary brake lever to the brake side, the exhaust brake is not immediately closed and the exhaust brake is not activated, but electric braking is performed. In this state, the generated energy can be used to charge the battery. As a result, energy that has been lost due to exhaust braking in the past can be used for charging the battery for hybrid travel, so that fuel efficiency associated with vehicle operation can be further increased. The present invention effectively reduces regenerative braking effectively by minimizing the energy lost by auxiliary braking while keeping the number of operation ends operated by the driver as one, without increasing the number of auxiliary braking operation ends. An apparatus that can be provided can be provided. This does not complicate the driving operation. The present invention can further increase the fuel efficiency (travelable distance per unit fuel capacity, for example, kilometers / liter) of a hybrid vehicle.

  FIG. 1 is a block diagram for explaining the functions around the engine of the embodiment of the present invention. The internal combustion engine 1 is a diesel engine, and its output shaft is directly connected to the rotating shaft of the motor generator 3. The rotating shaft is connected to the input shaft of the transmission 2 via the clutch 4. The drive shaft 5 on the output side of the transmission 2 is connected to the drive axle via a propeller shaft, a reduction gear, a differential gear, and the like. These structures are well known and are not shown because they are not directly related to the configuration of the present invention.

  The motor generator 3 is configured to supply a three-phase alternating current from an inverter 7 to a stator winding that is a field winding. A battery 6 is connected to the DC terminal of the inverter 7. The battery 6 is a large-capacity high-voltage battery, and in this embodiment, a large number of cells and units are connected in series. As an example, the overall rated terminal voltage is 350V. The inverter 7 converts the direct current supplied from the battery 6 into three-phase alternating current and supplies it to the motor generator 3, or converts the three-phase alternating current supplied from the motor generator 3 into direct current and supplies it to the battery 6. To do. That is, electric energy is supplied after being converted from direct current to alternating current or from alternating current to direct current. The inverter 7 is configured by a combination of a plurality of semiconductor switch elements, and can transmit electric energy bidirectionally according to control between the DC terminal and the AC terminal. The switching frequency of the inverter 7, that is, the generated three-phase AC frequency or phase rotation speed is controlled by the hybrid control circuit 16 via the interface 15. The main part of the hybrid control circuit 16 is constituted by a program control circuit. Since the configuration of these electric devices or electric circuits is well known, further detailed explanation is omitted here.

  In the hybrid power unit having this structure, when the driver depresses the accelerator pedal 14, the hybrid control circuit 16 generates the phase rotation speed generated in the motor generator 3 by the three-phase AC supplied from the inverter 7. 3 so that the motor generator 3 is set to the drive mode. At this time, the motor generator 3 acts as an electric motor, supplies a rotational driving force to the driving shaft 5 and assists the driving force of the internal combustion engine 1 to rotationally drive the axle. When the vehicle is decelerated, the driver releases the accelerator pedal 14 so that the internal combustion engine 1 enters an engine brake state. At the same time, the hybrid control circuit 16 can set the motor generator 3 as a generator to the braking mode and brake the rotation of the drive shaft 5, that is, the rotation of the axle. The motor generator 3 is supplied with electric energy from the battery 6 when operating as a motor in the driving mode, and regeneratively supplies electric energy to the battery 6 when operating as a generator in the braking mode. In response to this, the battery 6 repeats discharging or charging.

  The hybrid battery 6 is constituted by a series connection of a large number of cells, and the terminal voltage thereof is a high voltage (eg, 350 V) as described above. Since this high voltage cannot be directly supplied to an illumination lamp or other general electric equipment equipped in this vehicle, a DC-DC conversion circuit 18 is provided to output the output voltage of the battery 6 to that of a normal in-vehicle electric equipment. It is converted to DC 24V (or 12V) corresponding to the terminal voltage. The device connected to the output terminal of the DC-DC conversion circuit 18 is not shown in this drawing.

  Furthermore, this device is provided with an exhaust braking valve 8 in the exhaust passage of the internal combustion engine 1. The exhaust brake valve 8 is controlled to open and close by a drive motor 9. The exhaust brake valve 8 is in an “open” state during normal travel, and exhausts the exhaust gas from the internal combustion engine 1 to the outside air. When the exhaust braking valve 8 is in the “closed” state, the exhaust flow is restricted and the rotational speed of the internal combustion engine 1 is reduced, so that the internal combustion engine 1 reduces the vehicle speed, that is, the vehicle is in a braking state (engine Brake state). In the conventional apparatus, the opening and closing of the exhaust braking valve 8 is configured to be interlocked with the operation of the auxiliary braking operation end 10 operated by the driver, and the operation state of the auxiliary braking operation end 10 is determined via the interface 15. Thus, the hybrid control circuit 16 is also incorporated. The drive current of the exhaust brake valve 8 is obtained from the output of the DC-DC conversion circuit 18.

  The feature of the present invention lies in the control when the auxiliary braking operation end 10 is operated to the “braking” state by the driver while the vehicle is traveling. That is, as in the conventional device, the drive motor 9 is not immediately controlled by the operation output of the auxiliary braking operation end 10 to control the exhaust brake valve 8 to the “closed” state, but this operation output is temporarily set to the hybrid control circuit 16. The exhaust brake valve 8 is controlled by the control of the hybrid control circuit 16.

  FIG. 4 is a flowchart for explaining the control related to the braking valve control of the hybrid control circuit 16. When the hybrid control is in the regenerative mode due to the vehicle traveling downhill or decelerating, the hybrid control circuit 16 causes the battery charge capacity (SOC, State of Charge, percentage display for fully charged state) is detected. This is performed by fetching signals from the battery voltage detection device 17 and the battery current detector 19 and executing a calculation set in the hybrid control circuit 16. When the charging capacity of the battery 6 is less than the predetermined value X%, the exhaust braking is set to “OFF”, that is, an invalid state so that the regenerative torque generated with respect to the rotational speed, that is, the amount of power generated by the motor generator 3 increases. To control. When the charge capacity of the battery 6 is equal to or greater than the predetermined value X%, the exhaust braking is similarly set to “OFF”, and control is performed so that the regeneration torque is gradually reduced from a large regenerative torque state. This is shown as control by the A map in FIG.

  Further, when the auxiliary braking operation end 10 is set to “OFF”, the magnitude of the regenerative braking is controlled depending on whether the charging capacity of the battery 6 is less than a predetermined value Y% or more than Y%. Here, Y> X. This is control by the B map shown in FIG.

  FIG. 5 will be described in more detail. This is a characteristic diagram of this control. FIG. 5 shows the charging capacity of the battery 6 on the horizontal axis and the magnitude of the regenerative torque on the vertical axis. That is, a state is shown in which the regenerative torque, that is, the generated energy is controlled to decrease as the charge capacity increases and approaches the full charge capacity (100%). In this example, two types of maps, the A map and the B map, are set, and one of them is adopted depending on whether the charging capacity of the battery 6 at the time of starting regeneration is smaller or larger than X%. When the charging capacity is smaller than X%, that is, when the battery is hungry, the regenerative torque is increased, that is, the charging current is controlled to be large according to the A map. When the charging capacity of the battery is relatively large, the regenerative torque is controlled to be small according to the B map, that is, the charging current is controlled to be small. After the charge capacity reaches X% or Y%, the regenerative torque is reduced as the charge capacity increases, and the regenerative torque is reduced to zero at the preset charge capacity Z%. This point of charge capacity Z% is set slightly lower than the point of charge capacity 100%. Specific numerical values of the control characteristics, such as A, B, X, and Y, are selected according to individual specifications or characteristics of the battery 6, respectively.

  FIG. 6 illustrates characteristics of the regenerative torque with respect to the generator (motor generator) rotation speed. Depending on whether the A map or the B map described above is employed, the regenerative torque has characteristics as illustrated. A map corresponds to when exhaust braking is turned off, and B map corresponds to when exhaust braking is turned on. The torque To in FIG. 6 represents the torque corresponding to the absorption torque of exhaust braking. Thus, according to the control of the present invention, a larger regenerative torque can be obtained by the control using the A map that does not use the exhaust braking. That is, according to the present invention, the energy regenerated in the battery can be increased.

  The charging capacity and the like are indicated by symbols such as X, Y, and Z for easy understanding of the principle description. However, the inventor of the present application uses the technique described in [Non-Patent Document 1]. Specific figures were determined. When the present invention is implemented for batteries having different properties, the detection of charging capacity and the like can be implemented with reference to the description described in the above [Non-Patent Document 1].

  In the above description, the hybrid vehicle in which the rotary shaft of the internal combustion engine and the rotary shaft of the motor generator are directly connected has been described. However, this principle can be similarly applied to other hybrid vehicles.

1 is a block diagram of a hybrid vehicle according to an embodiment of the present invention. The figure which shows the conventional form which takes in an auxiliary | assistant braking operation end output to an internal combustion engine control circuit and a hybrid control circuit. The figure which shows the form which takes in the auxiliary | assistant braking operation end output of this invention Example to an internal combustion engine control circuit and a hybrid control circuit. The principal part flowchart explaining the braking control of this invention Example hybrid vehicle. The figure explaining the regenerative torque with respect to the battery charge state of this invention Example apparatus. The figure explaining the regenerative torque with respect to the engine rotational speed of the hybrid vehicle of this invention Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Transmission 3 Motor generator 4 Clutch 5 Drive shaft 6 Battery 7 Inverter 8 Exhaust brake valve 9 Drive motor 10 Auxiliary brake operation end 11 Fuel pump 12 Control device (internal combustion engine governor)
DESCRIPTION OF SYMBOLS 13 Internal combustion engine control circuit 14 Accelerator pedal 15 Interface 16 Hybrid control circuit 17 Battery voltage detection apparatus 18 DC-DC conversion circuit 19 Battery current detector 20 Internal combustion engine rotation detector 21 Transmission position detector

Claims (5)

In a hybrid vehicle equipped with both regenerative braking means and exhaust braking means as auxiliary braking means,
An auxiliary braking operation end operated by the driver during the traveling is provided in common for regenerative braking and exhaust braking,
When auxiliary braking is input from the operating end, according to the chargeable margin of the main battery measured at that time (a) Only regenerative braking,
(B) Combined use of regenerative braking and exhaust braking,
(C) Exhaust braking only
A hybrid vehicle provided with control means for preferentially activating auxiliary braking in the order of   When changing from (b) the combined use of regenerative braking and exhaust braking to (c) exhaust braking only, the mode is changed to another mode, and thereafter (c) means for changing only to exhaust braking is included. Item 2. The hybrid vehicle according to item 1. An electric motor and a generator comprising an internal combustion engine for driving an axle and exhaust braking means for decelerating the vehicle by partially closing an exhaust passage of the internal combustion engine, and further applying an auxiliary driving force and an auxiliary braking force to the vehicle, respectively A battery mounted on the vehicle, a charge state monitoring means for monitoring a charge state of the battery, a drive mode for supplying a drive current from the battery to the electric motor, or a current generated by the generator as a charge current In a hybrid vehicle comprising hybrid control means for setting and controlling the braking mode supplied to the battery,
An auxiliary braking operation end that is operated by a driver and controls the activation of the exhaust braking means and the activation of the braking mode by one operation end;
When the auxiliary braking operation end is operated in a braking state while the vehicle is running, the braking force generated by the generator is determined by the braking force generated by the exhaust braking unit according to the output of the battery charge state monitoring unit. A hybrid vehicle comprising control means for giving priority.   The electric motor and the generator include a control circuit for supplying a current to one rotating machine and a winding of the rotating machine, and control means for causing the rotating machine to act as an electric motor or a generator according to a control mode of the control circuit. The hybrid vehicle according to claim 3 provided.   The hybrid vehicle according to claim 3 or 4, wherein the auxiliary braking operation end includes means for controlling the braking force generated by the auxiliary braking.

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