JP2000297669A - Control device of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize longer service life of a battery by improving early activation of a catalyst, when the catalyst has not reached activation temperature and preventing overcharging of the battery. SOLUTION: When an engine is cold and the battery is in a chargeable state, the engine is controlled to a constant torque (S5) and the motor generator A, which is connected directly to the engine is controlled to a constant speed (S6). Since the engine runs in a state in which a load is applied by the motor generator, the time for the engine to warm up completely is shortened, and the catalyst can be activated early. Also, when the remaining capacity of the battery is equal to or greater than a prescribed value, the engine is stopped and running is done with a motor for running. As a result, overcharging of the battery is prevented and longer service life of the battery realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid vehicle in which a constant load is applied to an engine by a motor / generator until the catalyst reaches an activation temperature to raise the temperature of exhaust gas to realize early activation of the catalyst. It relates to a control device.

[0002]

2. Description of the Related Art In recent years, hybrid vehicles that use both an engine and a motor have been developed for vehicles such as automobiles from the viewpoint of low pollution and resource saving. Many technologies have been adopted to mount two motors to improve the efficiency of power energy recovery and ensure running performance.

[0003] Even in such a hybrid vehicle, harmful components such as HC, CO and NOx contained in the exhaust gas of the engine must be purified by a catalyst from the viewpoint of environmental protection.

However, since the catalyst does not function sufficiently to purify exhaust gas until the catalyst reaches the activation temperature, harmful components are temporarily large in high-load operation in a cold state of the engine, such as during start-up acceleration operation during warm-up. It is discharged to.

[0005] Therefore, for example, Japanese Patent Application Laid-Open No. 6-165308
In the publication, a warm-up completion time is set based on the catalyst temperature immediately after the engine is started, a schedule for gradually increasing the engine speed based on the warm-up completion time and a schedule for gradually increasing the charge amount are set. There is disclosed a technique for setting and limiting the exhaust gas emission amount according to the activation state of the catalyst.

[0006]

However, since the hybrid vehicle can be driven by the driving motor, the engine can be stopped when the vehicle is running. In some cases, the amount of emission is reduced, the catalyst temperature is reduced, and the purification ability of the catalyst is reduced.

However, in the above-mentioned prior art, the completion of warm-up is set based on the catalyst temperature immediately after the engine is started, and the catalyst temperature is raised by controlling the engine speed to gradually increase within the set time. However, since the time until the completion of warm-up is long and the engine speed cannot be increased in response to the sudden acceleration requested by the driver immediately after the engine is started, it is not possible to cope with the problem at an early stage, resulting in a sense of operation discomfort.

In addition, when the catalyst is inactive immediately after starting, the engine speed and the engine torque are controlled by the power generation operation of the motor / generator. However, when the battery is fully charged, it is overcharged and the battery is overcharged. Deterioration will be accelerated.

In view of the above circumstances, the present invention increases the exhaust gas temperature by applying an engine load when the catalyst has not reached the activation temperature, thereby actively activating the catalyst at an early stage, and at the same time, overheating the battery. It is an object of the present invention to provide a hybrid vehicle control device that can prevent charging and can prolong the life of a battery.

[0010]

In order to achieve the above object, a hybrid vehicle control device according to the present invention provides a hybrid vehicle in which an engine, a motor / generator, and a traveling motor are combined, in which the engine cold state is determined from the engine temperature. Means for determining and, when the engine is in a cold state, controlling the engine at a constant torque by the power generation operation of the motor / generator and controlling the motor / generator at a constant speed, and raising the temperature until the catalyst reaches the activation temperature. Means.

In this case, preferably, there is provided means for detecting a remaining battery capacity when the engine is in a cold state and stopping the engine when the engine is in a fully charged state and running the vehicle with the running motor. I do.

That is, in the present invention, when the engine is in a cold state, the engine is controlled at a constant torque and the motor / generator is controlled at a constant rotational speed. By increasing the temperature of the exhaust gas, the catalyst can be activated early by raising the temperature, the completion time of warm-up can be shortened, and the driver can quickly respond to a sudden acceleration request immediately after the engine is started. Can be eliminated.

In this case, it is preferable to detect the remaining capacity of the battery when the engine is cold and to stop the engine when the engine is fully charged, thereby preventing overcharging.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 2 shows the configuration of the drive control system of the hybrid vehicle employed in the present embodiment.

In FIG. 1, reference numeral 1 denotes an engine. A motor (motor / generator) A is directly connected to an output shaft 1a of the engine 1, and a catalyst 1c is interposed in an exhaust passage 1b of the engine 1.

The hybrid vehicle employed in the present embodiment is a vehicle that uses both an engine and a motor. The motor A is responsible for starting, power generation and power assist, and the motor A
And a motor (running motor) B that controls the functions of the planetary gear unit 3 and that serves as a driving force source for starting and reversing and regenerates deceleration energy, and performs speed change and torque amplification. And a power conversion mechanism 4 having a power conversion function during traveling.

More specifically, the planetary gear unit 3
The sun gear 3a includes a carrier 3b rotatably supporting a pinion meshing with the sun gear 3a, and a single pinion type planetary gear having a ring gear 3c meshing with the pinion.
And a lock-up clutch 2 for engaging and releasing the lock.

As the power conversion mechanism 4, a transmission combining a gear train, a transmission using a fluid torque converter, and the like can be used. The primary pulley 4b supported by the input shaft 4a and the transmission It is desirable to employ a belt-type continuously variable transmission (CVT) in which a drive belt 4e is wound around a secondary pulley 4d which is supported by the output shaft 4c. The conversion mechanism 4 will be described as CVT4.

That is, in the drive system of the hybrid vehicle according to the present embodiment, the planetary gear unit 3 having the lock-up clutch 2 interposed between the sun gear 3a and the carrier 3b includes the output shaft 1a of the engine 1 and the input shaft 4a of the CVT 4. The sun gear 3a of the planetary gear unit 3 is coupled to the output shaft 1a of the engine 1 via one motor A, and the carrier 3b is
The other motor B is connected to the input shaft 4a of the VT 4 and is connected to the ring gear 3c.

Further, a differential mechanism 6 is connected to an output shaft 4c of the CVT 4 via a reduction gear train 5, and a drive wheel 8 for a front wheel or a rear wheel is connected to the differential mechanism 6 via a drive shaft 7. I have.

In this case, as described above, the motor A directly connected to the engine 1 is connected to the sun gear 3a of the planetary gear unit 3 and the motor B is connected to the ring gear 3c to obtain an output from the carrier 3b.
Since the output from the carrier 3b is shifted and torque amplified by the CVT 4 and transmitted to the drive wheels 8,
The motors A and B can be used for both power generation and driving force supply, and a relatively small output motor can be employed.

The sun gear 3a of the planetary gear unit 3 is operated by the lock-up clutch 2 according to running conditions.
And the carrier 3b, the motors A and B
Can be formed, and a drive shaft directly connected to the engine from the engine 1 to the CVT 4 can be formed.
, Or the braking force from the driving wheel 8 side can be used.

Note that the torque flow of the engine 1 and the motors A and B via the planetary gear unit 3 when the lock-up clutch 2 is engaged and disengaged and the flow of electricity due to power generation are described in detail in Nippon 10-408
Since it is described in detail in No. 0, the description here is omitted.

The above drive system is controlled by a control system (hybrid control system) for controlling the running of a hybrid vehicle in which seven electronic control units (ECUs) are connected by a multiplex communication system. Are composed of a microcomputer and a functional circuit controlled by the microcomputer. It is desirable to employ a communication network capable of supporting high-speed communication as a multiplex communication system that connects the ECUs. For example, a CAN (Controller Area Network), which is one of the ISO standard protocols, is used as a vehicle communication network. Can be adopted.

More specifically, a hybrid ECU (HEV_ECU) 20 for controlling the whole system is mainly used, and a motor A controller 21 for controlling the driving of the motor A, a motor B controller 22 for controlling the driving of the motor B, and the engine 1 are controlled. Engine ECU (E / G_ECU) 2
3, a transmission ECU (T / M_ECU) 24 for controlling the lock-up clutch 2 and the CVT 4, and a battery management unit (BAT_MU) 25 for managing the power of the battery 10 include a first multiplex communication line 3.
A brake ECU (BRK_ECU) 26 that is connected to the HEV_ECU 20 at 0 and performs brake control is connected to the HEV_ECU 20 via a second multiplex communication line 31.

The HEV_ECU 20 controls the entire hybrid control system, and includes sensors and switches for detecting a driving operation state of the driver, for example, an accelerator pedal sensor (APS) 11 for detecting an amount of depression of an accelerator pedal (not shown). A brake switch 12 which is turned on by depressing a brake pedal (not shown);
An inhibitor switch 14 and the like, which are turned on when the operation position of the select mechanism 13 of the transmission is in the P range or the N range and turned off when the transmission is set in the D range, the R range, or the like, are connected.

The HEV_ECU 20 calculates the required vehicle drive torque based on signals from the sensors and switches and data transmitted from the ECUs, determines the torque distribution of the drive system, and performs multiplex communication on each ECU. To send a control command.

The HEV_ECU 20 has various indicators for displaying the operating state of the vehicle such as the vehicle speed, the engine speed, the state of charge of the battery and the like, and a display 27 comprising a warning lamp for warning the driver when an abnormality occurs. Is connected. The indicator 27 is also connected to the T / M_ECU 24, and when an abnormality occurs in the HEV_ECU 20, the T / M_ECU 2 replaces the HEV_ECU 20.
4 performs an abnormal-time control, and displays an abnormality on the display 27.

On the other hand, the motor A controller 21 has an inverter for driving the motor A,
Basically, the constant rotation speed control of the motor A is performed by a servo ON / OFF command and a rotation speed command transmitted from the HEV_ECU 20 by multiplex communication. Further, the motor A controller 21 feeds back the torque, rotation speed, current value, and the like of the motor A to the HEV_ECU 20, and transmits data such as a torque limit request and a voltage value.

The motor B controller 22 includes an inverter for driving the motor B, and basically includes a servo ON / OFF (including forward rotation and reverse rotation) command and torque transmitted from the HEV_ECU 20 by multiplex communication. The constant torque control of the motor B is performed by a command (powering, regeneration). Also, HE from the motor B controller 22
The torque, the number of revolutions, the current value, and the like of the motor B are fed back and transmitted to the V_ECU 20, and data such as the voltage value is transmitted.

The E / G_ECU 23 basically controls the torque of the engine 1, and the HEV_ECU 20
And positive / negative torque commands, fuel cut commands, air-conditioner ON / OFF permission commands, and other control commands transmitted by multiplex communication, actual torque feedback data, vehicle speed, and shift select position (P, N) by the inhibitor switch 14.
Range, etc.), accelerator full-open data and accelerator full-close data by APS11 signal, brake switch 12 O
N, OFF state, a fuel injection amount from an injector (not shown) based on a brake operation state including ABS, E
Throttle opening by TC (electric throttle valve), A /
It controls power correction learning of auxiliary equipment such as C (air conditioner) and fuel cut.

In the E / G_ECU 23, HEV_
The ECU 20 issues a control torque value of the engine 1, a fuel cut, a full-open increase correction to the fuel injection amount,
The HEV_ECU sends the ON / OFF state of the air conditioner, data on the throttle valve fully closed by an idle switch (not shown), and the like.
When the engine is cold, a warm-up request signal for the engine 1 and the like are transmitted.

T / M_ECU 24 is provided by HEV_ECU 2
From 0, CVT4 target primary rotation speed, CVT input torque instruction, control command such as lock-up request, etc., and E / G rotation speed, accelerator opening,
The lock-up clutch 2 is based on information such as the shift select position by the inhibitor switch 14, the ON / OFF state of the brake switch 12, the air conditioner switching permission, the brake operation state including the ABS, and the throttle valve fully closed data of the engine 1 by the idle switch. And the gear ratio of the CVT 4 are controlled.

From the T / M_ECU 24, the HEV
_ECU 20 for vehicle speed, input limiting torque, CVT4
The data of the primary rotation speed and the secondary pulley rotation speed, the lockup completion, the shift state corresponding to the inhibitor switch 14, and the like are fed back and transmitted.
An E / G rotation speed increase request, a low temperature start request, and the like for increasing the oil amount of the CVT 4 are transmitted.

The BAT_MU 25 is a so-called power management unit, and performs various controls for managing the battery 10, that is, performs charge / discharge control of the battery 10, fan control, external charge control, and the like.
The HEV_ECU 20 multiplexes data such as a state of charge (SOC), a voltage, and a current limit value detected based on the output current and the battery temperature, and data indicating that external charging is being performed.
Send to When performing external charging, the contactor 9 is switched to disconnect the battery 10 from the motor A controller 21 and the motor B controller 22.

The BRK_ECU 26 is provided by the HEV_ECU 2
A necessary braking force is calculated based on information such as a regenerable amount and regenerative torque feedback transmitted by multiplex communication from 0, and a hydraulic pressure of a brake system is controlled.
A regenerative amount command (torque command), a vehicle speed, a hydraulic pressure, a brake operation state including ABS and the like are fed back and transmitted to the HEV_ECU 20.

The driving modes of the hybrid vehicle controlled by the above-described hybrid control system can be roughly divided into the following three basic modes when viewed from the transmission input shaft. Is repeated. (1) Series (series & parallel) traveling mode When the required driving force is small, the lock-up clutch 2 is disengaged, the motor A is driven by the engine 1 as a generator, and mainly the motor B travels. At this time, part of the driving force of the engine 1 is input to the sun gear 3a of the planetary gear unit 3, is combined with the driving force of the motor B of the ring gear 3c, and is output from the carrier 3b. (2) Parallel traveling mode When the required driving force is large, the lock-up clutch 2 is engaged to couple the sun gear 3a of the planetary gear unit 3 and the carrier 3b, and the driving force of the motor B from the ring gear 3c is applied to the driving force of the engine 1. The added value is output from the carrier 3b, and the vehicle travels using the torque of the engine 1 alone or both the engine 1 and the motor B. (3) Regenerative braking mode During deceleration, regenerative braking is performed by the motor B in cooperation with brake control. That is, the regenerative braking is performed by cooperatively sharing the braking torque corresponding to the depression amount of the brake pedal with the regenerative torque by the motor B and the braking torque by the brake mechanism.

When the engine is cold, the series running mode is basically selected. In this case, the engine 1 is controlled at a constant torque by the E / G_ECU 23 and the motor A
Is controlled by the motor A controller 21 at a constant rotation speed.

That is, in the series running mode in the engine cold state, the engine 1 is controlled at a constant torque and the motor A
Is controlled at a constant speed, that is, by maintaining the engine 1 at a constant speed and applying the same load, the exhaust gas temperature is increased, the catalyst 1c is activated early, and the warm-up completion time is shortened. However, it is possible to promptly respond to the driver's request for rapid acceleration immediately after the engine is started, and it is possible to eliminate an uncomfortable operation.

The running control by the HEV_ECU 20 when the engine is cold is specifically processed by a running control routine shown in FIG.

First, at step S1, the E / G_ECU 2
It is checked whether a warm-up request signal has been output from 3 or not. If the warm-up request signal has been output, the process proceeds to step S2 because the engine is in a cold state. E / G_ECU23
Then, the engine temperature is detected from the cooling water temperature, the oil temperature, or the like, and when the engine temperature is equal to or lower than the set value, the catalyst 1c temperature is estimated to be equal to or lower than the activation temperature and a warm-up request signal is output.

In step S2, it is determined whether or not the battery 10 is fully charged based on whether or not the state of charge (SOC) of the battery 10 is equal to or greater than a predetermined value (for example, the SOC is 70%).
When the state of charge is equal to or more than the predetermined value, the process proceeds to step S3, and a command to stop the engine 1 is given to the E / G_ECU 23 by multiplex communication.

In the E / G_ECU 23, the HEV_ECU
In accordance with an engine stop command from the engine 20, processing such as fuel cut or fuel cut and ignition cut is performed to stop the engine.

Then, the process proceeds to step S4, in which a rotation speed command for rotating the motor A at a constant speed is given to the motor A controller 21 and a rotation speed command corresponding to the accelerator pedal depression amount is given to the motor B controller 22. Exit the routine.

In the motor A controller 21, HEV_
The motor A spontaneously rotates at a constant speed in accordance with a constant rotation speed command from the ECU 20. Further, the motor B controller 22 rotates the motor B at a rotation according to a rotation speed command according to the accelerator pedal depression amount from the HEV_ECU 20.

As a result, the motor B transmits the driving force to the CVT 4 in the planetary gear unit 3 while being supported by the reaction force from the motor A, and causes the vehicle to run. Accordingly, when the battery 10 is fully charged, the power generation operation of the motor A is stopped, so that overcharging is prevented, and
0, and the engine 1 is stopped even when the catalyst 1c is in an inactive state.
No harmful components in the exhaust gas are released to the atmosphere.

On the other hand, if it is determined in step S2 that the remaining capacity of the battery 10 is equal to or less than the set value, the battery can be charged, and the process proceeds to step S5, where a constant torque command is output to the E / G_ECU 23, and At S6, the motor A
A constant rotation speed command is given to the controller 22.

Then, the process proceeds to a step S7, wherein a rotation speed command corresponding to the accelerator pedal depression amount is given to the motor B controller 22, and the routine is exited.

As a result, in the E / G_ECU 23, HE
In response to a constant torque command from the V_ECU 20, the engine 1
Control the ISC (idle speed control) valve or the throttle valve opening of the engine 1 to control the constant torque of the engine 1.
In the motor A controller 22, HEV_ECU2
The motor A is controlled at a constant rotational speed in response to a constant rotational speed command from 0 to generate electric power, and the obtained electric power is charged into the battery 10.

In the motor B controller 22, HE
The motor B is rotated by a rotation according to a rotation speed command according to the accelerator pedal depression amount from the V_ECU 20.

As described above, when the engine 10 is in a cold state and the charge capacity of the battery 10 has room,
By controlling the motor A at a constant rotational speed, that is, by maintaining the engine 1 at a constant speed and applying the same load, thereby raising the exhaust gas temperature and thereby quickly activating the catalyst 1c. As a result, the warm-up completion time can be shortened, and a sudden acceleration request immediately after the engine start of the driver can be promptly responded to, so that uncomfortable operation can be eliminated.

Thereafter, when it is determined in step S1 that the engine 1 has been completely warmed up, the process proceeds to step S8, in which the normal control for selecting the series running mode, the parallel running mode, and the braking regeneration mode according to the running situation. Do
Exit the routine.

When the series running mode, which is the running mode when the required driving force is small, is selected as the normal control, the engine 1 drives the motor A as a generator and the battery 10 is fully charged. In this state, since the engine 1 is stopped, the engine 1 may be cooled during traveling and enter a cold state. In such a case,
The normal control is again shifted to the above-described traveling mode when the engine is cold, and the warm-up operation with the constant torque and the constant rotation speed is performed. This normal control is described in detail in Japanese Patent Application No. 10-328640 previously filed by the present applicant.

Incidentally, when the parallel driving mode in which the required driving force is relatively large is selected as the normal control, the torque of the engine 1 is also output for driving. There is no cooling, and therefore there is no transition from the parallel running mode to the running mode when the engine is cold during running.

[0055]

As described above, according to the present invention,
When the engine is in a cold state, the engine and the generator are controlled at a constant torque by the power generation operation of the motor / generator, and the motor / generator is controlled at a constant speed.
By maintaining the same speed and applying the same load, the exhaust gas temperature is raised to quickly activate the catalyst, shorten the warm-up completion time, and promptly respond to the driver's sudden acceleration request immediately after engine start. It is possible to deal with it, and it is possible to eliminate a sense of incongruity in operation.

In this case, the remaining capacity of the battery is detected, and when the battery is fully charged, the engine is stopped.
By performing the traveling operation using the traveling motor, overcharging is prevented, and the life of the battery can be extended.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a traveling control routine.

FIG. 2 is an explanatory diagram showing a configuration of a drive control system of the hybrid vehicle.

[Explanation of symbols]

 Reference Signs List 1 engine 1c catalyst 10 battery A motor / generator B traveling motor

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Claims (2)

[Claims] In a hybrid vehicle in which an engine, a motor / generator and a traveling motor are combined, means for judging an engine cold state from an engine temperature, and when the engine is in a cold state, a power generation operation of the motor / generator. Means for controlling the engine at a constant torque, controlling the motor / generator at a constant speed, and increasing the temperature of the catalyst until the catalyst reaches an activation temperature. 2. The system according to claim 1, further comprising means for detecting a remaining battery capacity when the engine is in a cold state, and stopping the engine when the engine is in a fully charged state, and causing the engine to run using the running motor. The control device for a hybrid vehicle according to any one of the preceding claims.