JP2006220045A - Deceleration control method for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase energy recovery efficiency by increasing regeneration quantity during vehicle deceleration. <P>SOLUTION: This invention relates to a deceleration control method for a hybrid vehicle provided with an engine as a travel drive power source including a variable nozzle turbocharger (VNT) adjusting velocity of exhaust gas by opening change of a variable nozzle and increasing intake air quantity with using exhaust gas pressure and a motor generator capable of power operation and regeneration operation, and constructed to perform regeneration control by the motor generator during vehicle deceleration. When regeneration control by the motor generator is performed (Yes in step S20) during vehicle deceleration (Yes in step S10), the variable nozzle of the variable nozzle turbocharger is controlled to fully open. When regeneration control is not performed (No in the step S20), the variable nozzle is controlled to fully close (Step S32). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control method during deceleration of a vehicle, and more particularly to a control method during deceleration of a vehicle that can increase a regeneration amount and increase energy recovery efficiency when the vehicle is decelerated.

  Conventionally, a hybrid vehicle drive system has been proposed in which a motor generator capable of regenerative operation and power running operation is directly connected to the engine, and a starter motor is connected to the ring gear disposed on the outer periphery of the flywheel from the transmission housing side. (For example, refer to Patent Document 1). In such a hybrid vehicle, a motor generator is disposed between the engine and the clutch in order to collect kinetic energy at the time of vehicle deceleration as electric energy, and regenerative control is performed by the motor generator at the time of vehicle deceleration.

  As a related technique, when performing regeneration by a motor generator in a deceleration state of a vehicle, a technique is known in which a throttle valve is fully opened to reduce mechanical energy loss and improve regenerative energy efficiency (for example, (See Patent Document 2 and Patent Document 3).

Japanese Patent No. 3284183 JP-A-9-284916 JP 11-93724 A

  Now, an engine having a variable nozzle turbocharger that adjusts the flow rate of the exhaust gas by changing the opening of the variable nozzle and increases the intake amount by using the exhaust gas pressure is mounted on the vehicle as described above and controlled. In this case, the opening of the variable nozzle is adjusted based on the fuel injection amount instruction value calculated from the accelerator opening.

  However, normally, the fuel injection amount is reduced at the time of deceleration, and the variable nozzle is fully closed in consideration of the supercharging pressure delay at the time of reacceleration, etc., so that the exhaust pressure ( Back pressure) increases, and engine pumping loss (friction) increases. Therefore, when the regeneration control by the motor generator at the flywheel position at the time of deceleration is performed, there is a problem that the amount of regeneration decreases and the energy recovery efficiency decreases.

  In addition, large trucks or the like having a relatively small brake capacity compared to the vehicle weight are equipped with auxiliary brake means such as an exhaust brake and a retarder. When the auxiliary braking means is applied to decelerate the vehicle to apply auxiliary braking force and regenerative control is performed by the regenerative means such as the motor generator, the regenerative amount is reduced by the amount of the auxiliary braking force applied, and the energy is reduced. There was a problem that the recovery efficiency would decrease.

  The present invention has been made in view of the above, and an object of the present invention is to provide a vehicle deceleration control method that can increase the amount of regeneration during vehicle deceleration and increase the energy recovery efficiency.

  In order to solve the above-described problems and achieve the object, the vehicle deceleration control method according to claim 1 of the present invention uses the exhaust gas pressure by adjusting the flow rate of the exhaust gas by changing the opening of the variable nozzle. An engine having a variable nozzle turbocharger that increases the intake air amount and regenerative means that functions as a generator when the vehicle decelerates, and a vehicle that is configured to be able to perform regenerative control by the regenerative means when the vehicle decelerates. In the deceleration control method, when the regeneration control is performed by the regeneration means during vehicle deceleration, the variable nozzle is controlled to be fully opened.

  According to a second aspect of the present invention, there is provided a vehicle deceleration control method comprising: an engine as a travel drive source; regenerative means that functions as a generator during vehicle deceleration; and an auxiliary brake that applies an auxiliary braking force to the vehicle. And when the vehicle is decelerating, the auxiliary braking is performed when the vehicle is decelerating, and the regenerative control is performed by the regeneration unit. The braking force by the means is reduced.

  According to a third aspect of the present invention, there is provided a vehicle deceleration control method according to the second aspect of the present invention, wherein the auxiliary brake means is an exhaust throttle valve that throttles an exhaust passage of the engine. When the regeneration control by the regeneration means is performed, the exhaust throttle valve is controlled to be fully opened.

  According to a fourth aspect of the present invention, there is provided a vehicle deceleration control method according to the second aspect, wherein the auxiliary brake means loads a driving force transmitting member that transmits the driving force from the engine to the driving axle. When the regenerative control by the regenerative means is performed during vehicle deceleration, the retarder is prohibited from applying a load to the driving force transmission member.

  In the vehicle deceleration control method according to claim 5 of the present invention, in the invention according to any one of claims 1 to 4, the regeneration means regenerates electric power in conjunction with rotation of the engine. It is characterized by comprising at least one of an alternator and a motor generator capable of powering operation in addition to regenerative operation.

  According to the vehicle deceleration control method according to the present invention (Claim 1), the exhaust pressure (back pressure) is reduced by controlling the variable nozzle to be fully opened during deceleration regeneration, and the pumping loss (friction) of the engine is reduced. Is done. Therefore, the amount of regenerative energy regenerated by the regenerative means increases as the pumping loss is reduced, and fuel efficiency can be improved.

  According to the vehicle deceleration control method according to the present invention (Claim 2), by reducing the braking force by the auxiliary brake means at the time of deceleration regeneration, the kinetic energy corresponding to the braking force is converted into electric energy by the regeneration means. Therefore, the amount of regeneration can be increased, and fuel consumption can be improved.

  According to the vehicle deceleration control method according to the present invention (Claim 3), exhaust gas is not confined in the exhaust passage by controlling the exhaust throttle valve to be fully open during deceleration regeneration. And the pumping loss of the engine is reduced. Therefore, the amount of regenerative energy regenerated by the regenerative means increases as the pumping loss is reduced, and fuel efficiency can be improved.

  Further, according to the vehicle deceleration control method according to the present invention (Claim 4), it may be caused by applying the load by prohibiting the application of the load to the driving force transmission member by the retarder during the deceleration regeneration. Since the kinetic energy corresponding to the braking force can be recovered as electric energy by the regenerative means, the regenerative amount is increased and the fuel consumption can be improved.

  According to the vehicle deceleration control method according to the present invention (Claim 5), a normal vehicle having only an alternator as a regeneration means, a hybrid vehicle having a motor generator capable of power running as a regeneration means, or For a hybrid vehicle provided with both an alternator and a motor generator as regeneration means, the amount of regeneration can be increased when the vehicle is decelerated, and the energy recovery efficiency can be increased.

  Embodiments of a vehicle deceleration control method according to the present invention will be described below in detail with reference to the drawings. In addition, although the example which applied this invention to the diesel hybrid vehicle is demonstrated, this invention is not limited by this Example.

  First, a schematic configuration of a diesel hybrid vehicle will be described with reference to FIG. Here, FIG. 2 is a schematic diagram showing a schematic configuration of the diesel hybrid vehicle. As shown in FIG. 2, a diesel hybrid vehicle (vehicle) 10 is provided with a diesel engine (hereinafter simply referred to as an engine) 11 as a travel drive source.

  The engine 11 has a variable nozzle turbocharger 11a that adjusts the flow rate of the exhaust gas by changing the opening of the variable nozzle and increases the intake amount using the exhaust gas pressure. The variable nozzle turbocharger 11a is configured by known means.

  That is, in the variable nozzle turbocharger 11a, although the internal structure is not shown, an exhaust gas passage is formed along the rotational direction of the turbine so as to surround the outer periphery of the turbine. A variable nozzle for changing the flow rate of the exhaust gas blown to the turbine is provided.

  This variable nozzle includes a plurality of nozzle vanes and an actuator for opening and closing these nozzle vanes. The nozzle vanes are arranged at equal angles with the turbine axis as the center, and are opened and closed by an actuator in a synchronized state. This actuator is constituted by a pulse motor or the like, and is controlled by an electronic control unit (hereinafter referred to as ECU) which is a control device (not shown).

  The flow rate of the exhaust gas blown to the turbine is adjusted by opening and closing each nozzle vane in synchronism and changing the size of the gap between adjacent nozzle vanes. By adjusting the flow rate of the exhaust gas as described above, the rotational speed of the turbine is adjusted, and as a result, the amount of air forcedly fed into the combustion chamber is adjusted.

  The control operation of the variable nozzle will be described later when the motor generator 17 performs regenerative control or during normal deceleration without regenerative control.

  Although not shown, the engine 11 includes a common rail fuel injection system that controls the fuel injection amount and fuel injection timing, a variable valve timing mechanism that variably controls the opening / closing operation timing of the intake and exhaust valves, and the like. .

  Although not shown, in the exhaust passage of the engine 11, in order to purify particulate matter and nitrogen oxide (NOx) in the exhaust gas, a particulate filter carrying an NOx storage reduction catalyst, exhaust gas, An exhaust gas recirculation device that recirculates part of the gas to the intake system is provided. The filter may be a particulate filter that does not carry a catalyst or a particulate filter that carries an oxidation catalyst.

  Further, the driving force generated by the engine 11 and the motor generator 17 directly connected to the engine 11 includes a clutch 12a for connecting and separating power transmission, a stepped transmission (hereinafter referred to as MMT (multi-mode manual transmission)) capable of automatic transmission. 12), a differential gear 15 and a drive shaft (drive shaft) 14, which are transmitted to the drive wheels 13.

  The MMT 12 electrically and automatically controls a gear shift operation by an actuator in accordance with a traveling state. The clutch 12a is also electrically automatically controlled by an actuator according to the traveling state.

  Further, the engine 11 is configured such that its fuel injection amount, intake air amount, and the like are controlled in order to output the requested engine torque commanded from the MMT 12. The required fuel injection amount of the engine 11 is determined based on, for example, a map from the engine speed (rotation speed) and the accelerator opening, and is injected by the fuel injection system.

  Further, the motor generator 17 is connected to a battery 20 that is a chargeable / dischargeable secondary battery via an inverter 19, and is a power running operation mode that functions as a motor that is a travel drive source, and a regenerative operation mode that functions as a generator. It is comprised so that the two driving | running states can be taken.

  The motor generator 17 receives power supply from the battery 20 in the power running operation mode and generates power for driving the drive shaft 14 via the engaged clutch 12a, the MMT 12, and the differential gear 15. Thereby, the shift assist can be performed at the time of shifting, and the acceleration assist can be performed at the time of acceleration.

  Further, in the regenerative operation mode, the motor generator 17 converts the driving force from the engine 11 or the driving force transmitted from the drive shaft 14 during deceleration to charge the battery 20. The control of the engine 11 when the regenerative control is performed at the time of deceleration will be described later.

  Whether motor generator 17 is operated in the power running mode or the regenerative operation mode is determined in consideration of the state of charge (SOC) of battery 20. The battery charge state amount SOC is calculated by a predetermined battery state monitor computer.

  The diesel hybrid vehicle 10 configured as described above is basically controlled as described below by the ECU based on output information from various sensors such as a vehicle speed sensor and an accelerator opening sensor (not shown), and travels in various states. can do.

  When the diesel hybrid vehicle 10 is in a low-speed steady travel state with a small travel load, the motor generator 17 travels (EV travel) by powering with the fuel supply to the engine 11 stopped. When the diesel hybrid vehicle 10 reaches a predetermined speed or load after the start of traveling, the engine 11 is cranked and started using the motor generator 17, and the operation is shifted to the operation using the engine 11.

  Further, during an operation with a large traveling load such as acceleration, the power supply to the motor generator 17 is normally stopped, and the engine 11 is operated so as to generate an output substantially equal to the required power of the drive shaft 14. At this time, almost all of the output of the engine 11 is transmitted to the drive shaft 14.

  When the state of charge SOC of the battery has decreased below a predetermined reference value, the engine 11 is operated at an output higher than the required output of the drive shaft 14, and a part of the surplus power is supplied by the motor generator 17. And is used for charging the battery 20. When the output torque of the engine 11 is insufficient, the insufficient torque is assisted by operating the motor generator 17 according to the battery charge state amount SOC, and the necessary torque is ensured.

  The diesel hybrid vehicle 10 is also subjected to so-called eco-run (economy & ecology running) control in order to save fuel and reduce exhaust emissions. For example, when the diesel hybrid vehicle 10 stops due to a signal waiting at an intersection or the like, the engine 11 is automatically stopped under a predetermined stop condition, and thereafter, under a predetermined restart condition (for example, when an accelerator pedal is depressed). Control for restarting the engine 11 is also performed.

  The above is the basic configuration and basic control operation of the diesel hybrid vehicle 10 according to the present invention.

  Next, a control method at the time of deceleration of the diesel hybrid vehicle 10, which is a main part of the present invention, will be described with reference to FIG. 2 based on FIG. Here, FIG. 1 is a flowchart showing a control method during deceleration of the diesel hybrid vehicle 10 according to the first embodiment of the present invention.

  As shown in FIG. 1, first, it is determined whether or not the diesel hybrid vehicle 10 is decelerating (step S10). For example, when the accelerator opening that is always read in advance is smaller than a predetermined threshold for determining deceleration, it can be determined that the vehicle is decelerating. If it is determined that the vehicle is not decelerating (No at step S10), the process returns to the start because it is out of the scope of this control method.

  If it is determined that the vehicle is decelerating (Yes at Step S10), whether or not the regenerative control command flag signal to the motor generator 17 is ON, that is, whether or not regenerative control by the motor generator 17 has started. Is determined (step S20).

  If regenerative control by the motor generator 17 is started (Yes in step S20), the clutch 12a is engaged and the engine 11 is driven at a predetermined high speed, and a variable nozzle turbocharger (in FIG. A variable nozzle (not shown) 11a (not shown) is controlled to be fully opened (step S30).

  As a result, the exhaust pressure (back pressure) during deceleration regeneration is reduced, and the pumping loss (friction) of the engine 11 is reduced. Therefore, the amount of regenerative energy regenerated by motor generator 17 is increased by the reduction of the pumping loss, and fuel efficiency can be improved.

  On the other hand, if the regenerative control by the motor generator 17 is not started at the time of deceleration (Yes in Step S10, No in Step S20), the engine 11 is operated in a separate control routine (not shown) because the normal deceleration is not accompanied by the regenerative control. The variable nozzle (not shown) of the variable nozzle turbocharger 11a is controlled to be fully closed in consideration of a delay in supercharging pressure at the time of reacceleration and the like (step S32). Thereby, since the pumping loss of the engine 11 increases, a predetermined auxiliary braking force can be obtained.

  FIG. 3 is a schematic diagram illustrating a schematic configuration of a diesel hybrid vehicle according to Embodiment 2 of the present invention, and FIG. 4 is a flowchart illustrating a control method during deceleration of the diesel hybrid vehicle. In the following description, members that are the same as or correspond to those already described are denoted by the same reference numerals, and redundant description is omitted or simplified.

  As shown in FIG. 3, the engine 11 of the diesel hybrid vehicle 10 has an exhaust throttle valve 11b by a known means in an exhaust passage (not shown), and a predetermined auxiliary braking force (exhaust brake) by closing the exhaust throttle valve 11b. It is configured to obtain.

  That is, the diesel hybrid vehicle 10 closes the exhaust throttle valve 11b disposed in the exhaust passage to confine the exhaust gas in the exhaust passage, thereby increasing the back pressure and increasing the pumping loss of the engine 11. Is configured to apply an exhaust brake. The exhaust throttle valve 11b is configured to operate in an auto mode and a manual mode, and is controlled in the auto mode here. Other configurations are the same as those in the first embodiment.

  Next, a deceleration control method for the diesel hybrid vehicle 10 according to the second embodiment will be described with reference to FIG. 3 based on FIG. The contents of the step of determining whether or not the diesel hybrid vehicle 10 is decelerating and the step of determining whether or not the regenerative control by the motor generator 17 has been started are the steps S10 and S20 described in the first embodiment. Therefore, the same step numbers will be assigned and redundant description will be omitted, and only different points will be described.

  That is, as shown in FIG. 4, if the regenerative control by the motor generator 17 is started during deceleration (Yes at Step S10, Yes at Step S20), the exhaust throttle valve 11b is controlled to be fully opened (Step S40).

  When the exhaust throttle valve 11b is fully opened, the exhaust pressure is reduced, and the pumping loss of the engine 11 is reduced. Therefore, the amount of regenerative energy regenerated by motor generator 17 is increased by the reduction of the pumping loss, and fuel efficiency can be improved.

  On the other hand, if the regenerative control by the motor generator 17 is not started at the time of deceleration (Yes at Step S10, No at Step S20), it is normal deceleration without the regenerative control. 11 and the exhaust throttle valve 11b is controlled to be fully closed (step S42). Thereby, since the pumping loss of the engine 11 increases, a predetermined auxiliary braking force can be obtained.

  If the exhaust throttle valve 11b is set to the manual mode and the exhaust brake switch (not shown) is not operated (fully closed) by the driver, it is detected by other means. The exhaust brake is controlled to be applied.

  Although not shown in the drawings, the third embodiment is mounted on a propeller shaft (driving force transmission member) for transmitting engine driving force from the transmission to the driving axle, and the propeller shaft, and applies a load to the rotation. The present invention relates to a control method during deceleration of a diesel hybrid vehicle including a retarder (auxiliary brake means) that decelerates to obtain an auxiliary braking force and a motor generator as a regeneration means. The other basic configuration is substantially the same as that of the first embodiment, and therefore, the same or corresponding members are denoted by the same reference numerals and redundant description is omitted.

  Next, a deceleration control method for the diesel hybrid vehicle 10 according to the third embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing a deceleration control method for the diesel hybrid vehicle 10 according to the third embodiment of the present invention. The contents of the step of determining whether or not the diesel hybrid vehicle 10 is decelerating and the step of determining whether or not the regenerative control by the motor generator 17 has been started are the steps S10 and S20 described in the first embodiment. Therefore, the same step numbers will be assigned and redundant description will be omitted, and only different points will be described.

  That is, as shown in FIG. 5, if the regenerative control by the motor generator 17 is started at the time of deceleration (Yes at Step S10, Yes at Step S20), load application to the propeller shaft by the retarder is prohibited (Step S50). Control so that the auxiliary braking force does not work.

  Accordingly, the amount of regenerative energy regenerated by the motor generator 17 is increased by the amount that the auxiliary braking force by the retarder does not work, and the fuel consumption can be improved.

  On the other hand, if the regenerative control by the motor generator 17 is not started at the time of deceleration (Yes at Step S10, No at Step S20), it is normal deceleration without the regenerative control, so that the load is applied to the propeller shaft by the retarder. (Step S52). What is necessary is just to obtain a predetermined auxiliary braking force.

  In the third embodiment, the retarder is described as being mounted on the propeller shaft. However, the present invention is not limited to this, and the retarder may be mounted at other locations such as the output shaft of the transmission. The effect of can be expected.

  Moreover, in the said Example 1-Example 3, although applied applying this invention about the diesel hybrid vehicle 10 which uses the diesel engine 11 as a travel drive source, it is not limited to this, A gasoline engine is used as a travel drive source. You may apply to the hybrid vehicle which does.

  In the first to third embodiments, the present invention is applied to the diesel hybrid vehicle 10 including the clutch 12a and the MMT 12. However, the present invention is not limited to this, and a continuous continuously variable transmission (CVT), You may apply to the hybrid vehicle provided with the automatic transmission (AT) and the manual transmission (MT).

  Further, in the first to third embodiments, the diesel hybrid vehicle 10 including the motor generator 17 as the regenerating means has been described as an example. However, the present invention is not limited to this, and a normal drive using only the engine as a travel drive source is described. The present invention may be applied to a vehicle that includes an alternator that regenerates electric power in conjunction with the rotation of the engine as regeneration means, or a hybrid vehicle that includes both the alternator and the motor generator as regeneration means.

  As described above, the vehicle deceleration control method according to the present invention is useful for a vehicle configured to be able to perform regeneration control by regeneration means during deceleration, and in particular, performs regeneration control by a motor generator during deceleration, It is suitable for a hybrid vehicle that aims to increase the energy recovery efficiency by reducing the pumping loss of the engine to increase the regeneration amount.

It is a flowchart which shows the deceleration time control method of the diesel hybrid vehicle which concerns on Example 1 of this invention. It is a mimetic diagram showing a schematic structure of a diesel hybrid vehicle. It is a schematic diagram which shows schematic structure of the diesel hybrid vehicle which concerns on Example 2 of this invention. It is a flowchart which shows the control method at the time of deceleration of a diesel hybrid vehicle. It is a flowchart which shows the deceleration time control method of the diesel hybrid vehicle which concerns on Example 3 of this invention.

Explanation of symbols

10 Diesel hybrid vehicle (vehicle)
11 Diesel engine (engine)
11a Variable nozzle turbocharger 11b Exhaust throttle valve (auxiliary brake means)
17 Motor generator (regenerative means)

Claims (5)

An engine having a variable nozzle turbocharger that adjusts the flow rate of the exhaust gas by changing the opening of the variable nozzle and increases the intake air amount using the exhaust gas pressure;
Regenerative means that functions as a generator when the vehicle decelerates;
With
A vehicle deceleration control method configured to enable regenerative control by the regenerative means during vehicle deceleration,
A control method during deceleration of a vehicle, wherein when the regeneration control by the regeneration means is performed during vehicle deceleration, the variable nozzle is controlled to be fully opened. An engine as a travel drive source;
Regenerative means that functions as a generator when the vehicle decelerates;
Auxiliary brake means for applying auxiliary braking force to the vehicle;
With
A vehicle deceleration control method configured to enable regenerative control by the regenerative means during vehicle deceleration,
A control method for decelerating a vehicle, characterized in that when the regenerative control by the regenerative means is performed during vehicle deceleration, the braking force by the auxiliary brake means is reduced. The auxiliary brake means is an exhaust throttle valve that throttles an exhaust passage of the engine;
3. The vehicle deceleration control method according to claim 2, wherein when the regeneration control by the regeneration unit is performed during vehicle deceleration, the exhaust throttle valve is controlled to be fully opened. The auxiliary brake means is a retarder that applies a load to a driving force transmission member that transmits a driving force from an engine to a driving axle,
3. The vehicle deceleration control method according to claim 2, wherein when the regeneration control by the regeneration unit is performed during vehicle deceleration, the retarder is prohibited from applying a load to the driving force transmission member. 4.   The regenerative unit is configured by at least one of an alternator that regenerates electric power in conjunction with rotation of the engine and a motor generator that can perform power running operation in addition to regenerative operation. The vehicle deceleration control method according to any one of the above.

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