JP2015058783A - Control device of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a hybrid vehicle, which can achieve improvement of fuel economy by performing a fuel cut in an engine while operating accessories driven by the engine during coasting travel control.SOLUTION: A clutch 4 is interposed between an engine 2 and a motor 3, and the motor 3 is connected to a drive wheel 9 side to form a hybrid truck 1. A control device of the hybrid vehicle, when a start condition of coasting travel control is satisfied on the basis of such as off-operation of an accelerator pedal 14 by a driver, returns a transmission 5 to neutral and separates the engine 2 and the motor 3 from the drive wheels 9 side to coast the vehicle 1. During the coasting travel control, the control device of the hybrid vehicle performs a fuel cut in the engine 2 and keeps the engine 2 at an idle rotation speed by drive of the motor 3 to continue operation of accessories 2a.

Description

  The present invention relates to a control apparatus for a hybrid vehicle equipped with an engine and a motor as a driving source for traveling, and more particularly to coasting control for coasting a vehicle when traveling on a gentle downhill road or when decelerating the vehicle.

In recent years, hybrid vehicles equipped with an engine and a motor as driving power sources have been put into practical use for the purpose of improving fuel consumption and exhaust gas performance. For example, as described in Patent Document 1, there is a hybrid vehicle of this type in which a clutch is interposed between an engine and a motor and the motor is connected to the drive wheel side.
In such a hybrid vehicle, the motor can be regeneratively controlled and operated as a generator by reverse driving from the drive wheel side. Therefore, when driving downhill or when the vehicle is decelerating, the clutch is disengaged and the engine is disconnected from the motor side. Kinetic energy is collected as generated power, charged to a battery, and used for driving the motor thereafter.

Japanese Patent Laid-Open No. 11-164403

  By the way, as one of the technologies aimed at improving the fuel efficiency, coasting control for coasting a vehicle has been put into practical use. The coasting control is executed when the driver depresses the accelerator pedal and the brake pedal is not operated, for example, when traveling on a gentle downhill road. The vehicle is driven by inertia. For example, in the case of the hybrid vehicle disclosed in Patent Document 1, the engine and motor are disconnected from the drive wheel side by switching the transmission to the neutral state, thereby preventing wasteful fuel consumption while maintaining the vehicle speed.

  During coasting control, it is possible to shut off the fuel supply to the engine, that is, stop the engine by cutting the fuel, but the auxiliary machines driven by the engine also stop. Especially in large vehicles such as trucks, many types of auxiliary equipment such as brake system and steering system are driven by the engine, so it is realistic to stop all these auxiliary equipment during coasting control. Impossible. Therefore, in the conventional technique, the engine is continuously operated during the coast driving control, and there is still room for improvement in terms of fuel consumption. Needless to say, this problem cannot be solved by the technique in Patent Document 1 relating to motor regeneration control.

  The present invention has been made to solve such a problem, and the object of the present invention is to improve fuel efficiency by operating the auxiliary machines driven by the engine during coasting control while cutting the engine fuel. It is an object of the present invention to provide a control device for a hybrid vehicle that can achieve the above.

In order to achieve the above object, a control device for a hybrid vehicle of the present invention is equipped with an engine and a motor as a driving source for traveling, and is configured to drive auxiliary machinery by the engine, so that an accelerator pedal by a driver can be controlled. In a hybrid vehicle control device that performs coast running control for coasting the vehicle by separating the engine and motor from the drive wheel side by coast running control means when the vehicle transitions to a specific running state with an off operation, The coast running control means is characterized in that the engine is fuel-cut during coast running control, and the engine is driven by a motor and kept at a preset rotational speed.
Since the engine is driven by the motor during coasting control, the engine can be cut to reduce fuel consumption. The operation of the auxiliary machinery can be continued by driving the engine with the motor.

As another aspect, the coast running control means is configured so that when the coast running control is finished, the driving force of the motor is raised to increase the rotation speed of the engine so that the rotation is synchronized with the driving wheel side. It is desirable.
When coasting control is terminated, there is no need to temporarily increase the fuel injection amount of the engine in order to synchronize the rotation between the engine and the drive wheels, and further improvement in fuel consumption can be achieved.

As another aspect, it is provided with an auxiliary machine drive necessity determining unit that determines whether or not the auxiliary machine is being driven during coasting control, and the auxiliary machine drive necessity determining unit determines that the auxiliary machine needs to be driven. Sometimes, the engine is driven by the motor, and when it is determined by the auxiliary device drive necessity determination means that the driving of the auxiliary machinery is unnecessary, the engine is cut off and stopped without executing the driving by the motor. In addition, it is desirable to configure a coast running control means.
By stopping the engine during coasting control, power consumption of the motor for driving the engine can be reduced, so that further improvement in fuel consumption can be achieved.

As another aspect, it is desirable to configure the coast travel control means so that the engine is driven by the motor at a rotation speed optimum for the operation of the auxiliary machines during the coast travel control.
Auxiliary machinery can be maintained in an optimal operating state even during coasting control.

  According to the present invention, fuel efficiency can be improved by cutting the engine fuel while operating auxiliary machinery driven by the engine during coasting control.

It is a whole lineblock diagram showing the hybrid type truck carrying the control device of an embodiment. It is a time chart which shows the execution condition of coast driving control when driving on a gentle downhill road. It is a characteristic view which shows the relationship between the driving | operation area | region of an engine, and driving | operation efficiency. It is the figure which compared the fuel consumption reduction effect obtained at the time of the driving | running | working by HEV mode, and the coast driving | running | working control, respectively.

[First Embodiment]
A first embodiment in which the present invention is embodied in a control device for a hybrid truck will be described below.
FIG. 1 is an overall configuration diagram showing a hybrid truck on which the control device of this embodiment is mounted.
The hybrid truck 1 is configured as a so-called parallel hybrid vehicle, and may be referred to as a vehicle in the following description. A vehicle 1 is equipped with a diesel engine (hereinafter referred to as an engine) 2 as a driving power source and a motor 3 that can also operate as a generator such as a permanent magnet synchronous motor. A clutch 4 is connected to the output shaft of the engine 2, and an input side of the automatic transmission 5 is connected to the clutch 4 via a rotating shaft of the motor 3. A differential device 7 is connected to the output side of the automatic transmission 5 via a propeller shaft 6, and left and right drive wheels 9 are connected to the differential device 7 via a drive shaft 8.

  The automatic transmission 5 automates the connection / disconnection operation of the clutch 4 and the switching operation of the shift stage based on a general manual transmission. In this embodiment, the automatic transmission 5 has a shift stage of 12 forward speeds and 1 reverse speed. ing. Of course, the configuration of the transmission 5 is not limited to this, and can be arbitrarily changed. For example, the transmission 5 may be embodied as a manual transmission, or a so-called dual clutch automatic transmission having two power transmission systems. It may be embodied as a machine.

  A battery 11 is connected to the motor 3 via an inverter 10. The DC power stored in the battery 11 is converted into AC power by the inverter 10 and supplied to the motor 3 (power running control), and the driving force generated by the motor 3 is transmitted to the drive wheels 9 after being shifted by the automatic transmission 5. The vehicle 1 is made to travel. For example, when the vehicle 1 decelerates or travels on a downhill road, the motor 3 operates as a generator by reverse driving from the drive wheel 9 side (regenerative control). The negative driving force generated by the motor 3 is transmitted to the driving wheel 9 side as a braking force, and the AC power generated by the motor 3 is converted into DC power by the inverter 10 and charged to the battery 11.

  The driving force generated by the motor 3 is transmitted to the driving wheel 9 regardless of the state of connection / disconnection of the clutch 4, and the driving force generated by the engine 2 is driven only when the clutch 4 is connected. 9 side. Therefore, when the clutch 4 is disengaged, the positive or negative driving force generated by the motor 3 as described above is transmitted to the driving wheel 9 side, and the vehicle 1 travels. When the clutch 4 is connected, the driving force of the engine 2 and the motor 3 is transmitted to the driving wheel 9 side, or only the driving force of the engine 2 is transmitted to the driving wheel side, so that the vehicle 1 travels.

The vehicle ECU 13 is a control circuit for integrated control of the entire vehicle. For this purpose, the vehicle ECU 13 includes an accelerator sensor 15 that detects the operation amount θacc of the accelerator pedal 14, a brake switch 17 that detects the depression operation of the brake pedal 16, a vehicle speed sensor 18 that detects the speed V of the vehicle 1, and the rotation of the engine 2. Various sensors and switches such as an engine rotation speed sensor 19 for detecting the speed Ne and a motor rotation speed sensor 20 for detecting the rotation speed Nm of the motor 3 are connected.
The vehicle ECU 13 is connected with an actuator (not shown) for connecting / disconnecting the clutch 4 and an actuator for shifting the automatic transmission 5, and an engine ECU 22 for engine control and an inverter ECU 23 for inverter control. And a battery ECU 24 for managing the battery 11 are connected.

  The vehicle ECU 13 calculates a required torque necessary for the vehicle 1 to travel based on the accelerator operation amount θacc by the driver, and selects the travel mode of the vehicle 1 based on the required torque, the SOC of the battery 11, and the like. In this embodiment, an E / G mode that uses only the driving force of the engine 2, an EV mode that uses only the driving force of the motor 3, and an HEV mode that uses both the driving force of the engine 2 and the motor 3 are set as the traveling mode. The vehicle ECU 13 selects one of the travel modes.

  The vehicle ECU 13 converts the required torque into a torque command value to be output by the engine 2 or the motor 3 based on the selected travel mode. For example, in the HEV mode, the required torque is distributed to the engine 2 side and the motor 3 side, and torque command values for the engine 2 and the motor 3 are calculated based on the gear position at that time. In the E / G mode, the required torque is converted into a torque command value for the engine 2 based on the gear position, and in the EV mode, the required torque is converted into a torque command value for the motor 3 based on the gear speed.

  Then, the vehicle ECU 13 disconnects the clutch 4 in the EV mode and connects the clutch 4 in the E / G mode and HEV mode in order to execute the selected travel mode, and then sends a torque command value to the engine ECU 22 and the inverter ECU 23. Output as appropriate. Further, during traveling of the vehicle 1, the vehicle ECU 13 calculates a target gear position from a shift map (not shown) based on the accelerator operation amount θacc, the vehicle speed V, and the like, and the actuator 4 connects and disconnects the clutch 4 to achieve this target gear position. Executes operation and gear change operation.

  On the other hand, the engine ECU 22 executes injection amount control and injection timing control so as to achieve the travel mode and torque command value input from the vehicle ECU 13. For example, in the E / G mode and the HEV mode, the driving force is generated in the engine 2 with respect to the positive torque command value, and the engine brake is generated with respect to the negative torque command value. Further, in the EV mode, the engine 2 is stopped and held by stopping the fuel injection or is set in an idle operation state.

  Further, the inverter ECU 23 controls the motor 3 via the inverter 10 so as to achieve the travel mode and the torque command value input from the vehicle ECU 13. For example, in the EV mode or HEV mode, the motor 3 is controlled by powering the positive torque command value to generate a positive driving force, and the motor 3 is regeneratively controlled to the negative torque command value. Generate negative driving force. In the E / G mode, the driving force of the motor 3 is controlled to zero. Further, the battery ECU 24 detects the temperature of the battery 11, the voltage of the battery 11, the current flowing between the inverter 10 and the battery 11, etc., and sequentially calculates the SOC of the battery 11 from these detection results and outputs it to the vehicle ECU 13. To do.

  On the other hand, when the vehicle ECU 13 is traveling on a gentle downhill road or when decelerating immediately before a curve (both are in a specific traveling state), the accelerator pedal 14 is turned off by the driver (θacc = 0) and the brake pedal 16 is operated. When the vehicle is not operated, coast running control for coasting the vehicle 1 is executed (coast running control means). While it is desirable in terms of fuel efficiency to stop the engine 2 during coasting control, in the truck 1 as in the present embodiment, various types of auxiliary equipment 2a (shown in FIG. 1) such as a brake system and a steering system are provided. Since it is driven by the engine 2, the engine cannot be stopped. Therefore, it is necessary to continue to operate the engine 2 even during coasting control as in the conventional technique, which causes a problem in terms of fuel consumption.

  Therefore, in the present embodiment, after the engine 2 is fuel-cut during coast running control, measures are taken to continue the operation of the auxiliary machinery 2a by driving the engine 2 by the motor 3 (coast running control means). Hereinafter, processing executed by the vehicle ECU 13 during the coasting control will be described.

  Basically, coast driving control is executed based on an accelerator operation by the driver.In addition to this, in this embodiment, coast driving control is started promptly based on prediction of road conditions on the driving route of the own vehicle. Yes. In order to obtain road information, a navigation device 31 and a communication device 32 are connected to the vehicle ECU 13 as shown in FIG.

  The navigation device 31 stores map information in its own storage area in advance, and sequentially receives GPS information via an antenna while the vehicle 1 is traveling to identify the position of the vehicle on the map. Further, the communication device 32 performs road-to-vehicle communication with a roadside communication system of a data center installed on the roadside, and performs vehicle-to-vehicle communication with other vehicles traveling around. Examples of communication targets include map information that the vehicle does not have, road information (road curves and gradients, etc.), traffic information (congestion information, accident information, construction information, etc.), or local information (tourist spot information, etc.) The communication device 32 acquires such information from the roadside communication system and other vehicles, or conversely supplies the information to other vehicles.

The vehicle ECU 13 acquires these various types of information from the navigation device 31 and the communication device 32, and predicts road conditions on the traveling route of the vehicle. For example, when there is a gentle downhill road ahead on the traveling route of the host vehicle or when a curve exists ahead on the traveling route, the driver turns off the accelerator pedal 14 in response to them. Before, start coasting control. As a result, the execution period of the substantial coasting control is extended, and a higher fuel efficiency reduction effect is realized.
However, execution of coasting control based on prediction of such road conditions is not an essential requirement of the present invention. Therefore, the navigation device 31 and the communication device 32 may be omitted, and coast driving control may be performed based on the driver's accelerator operation or the like as usual.

FIG. 2 is a time chart showing the execution state of coasting control when traveling on a gentle downhill road, and a specific execution state will be described based on this figure.
In this example, the HEV mode is selected before the coasting control is started. For this reason, the clutch 4 is connected, and the driving force of the engine 2 and the motor 3 corresponding to the driver's required torque is transmitted to the driving wheel 9 side through a predetermined gear stage of the automatic transmission 5 so that the vehicle 1 travels. ing.
For example, when the start condition for coasting control is established based on the prediction of the downhill road on the traveling route of the own vehicle or the driver's operation of turning off the accelerator pedal 14, the clutch 4 is disconnected and the engine 2 is cut (fuel injection amount). = 0) is started (point a in FIG. 2), and an instantaneous negative driving force is applied to the motor 3 to reduce rotation (point b in FIG. 2).

  In parallel with this, the clutch 4 is connected after the gear position of the transmission 5 is returned to neutral (point c in FIG. 2), and a positive driving force is applied to the motor 3. Although the engine 2 itself loses driving force due to the fuel cut, it is motored by receiving the driving force of the motor 3, and the engine rotational speed Ne is maintained at a predetermined rotational speed (idle rotational speed in this embodiment). The coasting control is started by the above processing, the engine 2 and the motor 3 are disconnected from the drive wheel 9 side, and the vehicle 1 starts to coast.

Thereafter, for example, when the coasting control end condition is satisfied based on the restart of the accelerator operation by the driver, the clutch 4 is first disengaged (point d in FIG. 2), and the fuel injection amount of the engine 2 is temporarily raised. The engine speed Ne increases (point e in FIG. 2). Thereby, the engine 2 side is rotationally synchronized with the motor 3 side (drive wheel 9 side) after the re-gearing, and in this state, the re-gearing to a predetermined gear stage is performed (point f in FIG. 2). Immediately thereafter, the fuel injection amount of the engine 2 is raised and the engine 2 starts to operate, and the clutch 4 is connected via a half-clutch (point g in FIG. 2).
As a result, the engine 2 and the motor 3 are connected to the drive wheel 9 side, the driving of the engine 2 and the motor 3 according to the required torque is resumed, and the coasting control is ended. Therefore, after that, the driving force of the engine 2 and the motor 3 is transmitted to the driving wheel 9 side through a predetermined shift stage of the automatic transmission 5 so that the vehicle 1 travels.

As described above, in the control device for the hybrid truck 1 according to the present embodiment, the engine 2 is fuel-cut during the coasting control, and then the engine 2 is driven by the motor 3 to continue the operation of the auxiliary machinery 2a. Yes.
The motor 3 consumes electric power to drive the engine 2, and this point approximates that during traveling in the normal HEV mode in which the engine 2 is assisted by the motor 3. However, there is a great difference in terms of driving efficiency between the area of idling operation of the engine 2 originally performed during coasting control and the operation area of the engine 2 when traveling in the HEV mode.

FIG. 3 is a characteristic diagram showing the relationship between the operating range of the engine 2 and the operating efficiency. As indicated by hatching in the figure, the engine 2 is always operated in an efficient region in combination with the assist effect of the motor 3 while the vehicle 1 is traveling in the normal HEV mode. On the other hand, the efficiency of the engine 2 during idle operation is significantly poor, and it can be estimated that the engine 2 consumes more fuel.
In this embodiment, it is possible to save a large amount of fuel consumed by the idling operation with poor operation efficiency. Therefore, as shown in FIG. 4, the fuel consumption reduction effect (%) obtained during the coast driving control is sufficiently higher than that during driving in the normal HEV mode. As a result, according to the present embodiment, the operation of the auxiliary machinery 2a equipped in the engine 2 can be continued by driving the engine 2 with the motor 3 during the coasting control, and the engine 2 is cut in fuel to idle operation. Fuel consumption can be saved and fuel consumption can be improved.

  Here, in the present embodiment, the engine 2 is kept at the idle rotational speed by driving the motor 3 during the coasting control, but the engine rotational speed Ne at this time is not limited to this. Since the purpose of driving by the motor is to continue the operation of the auxiliary machinery 2a during the coast control, the engine 2 may be driven at a rotational speed Ne optimum for the operation of the auxiliary machinery 2a. As a result, the auxiliary machinery 2a can be maintained in an optimum operating state even during coasting control.

[Second Embodiment]
Next, a second embodiment in which the present invention is embodied in another control device for the hybrid type truck 1 will be described.
The overall configuration of the control device for the hybrid truck 1 of this embodiment is the same as that of the first embodiment shown in FIG. 1, and the difference is the engine that is executed when coasting control is terminated. There are two rotation synchronization methods. Therefore, common constituent parts are denoted by the same member numbers, description thereof is omitted, and differences are mainly described.

  The control procedure of this embodiment is indicated by a broken line in FIG. In this embodiment, even if the coast running control end condition is satisfied (point d in FIG. 2), the fuel injection amount of the engine 2 is maintained at 0 without being temporarily raised. Immediately before the clutch 4 is disengaged, the driving force of the motor 3 is temporarily raised to increase the engine rotational speed Ne (point g in FIG. 2). As a result, the engine 2 side is rotationally synchronized with the motor 3 side (drive wheel 9 side) after the re-gearing, and then the clutch 4 is disconnected and re-gearing is performed. The subsequent procedure is the same as in the first embodiment.

  As described above, in the present embodiment, the engine 2 is rotationally synchronized using the driving force of the motor 3 at the end of the coasting control. Therefore, there is no need to temporarily increase the fuel injection amount of the engine 2 for this rotation synchronization, and further improvement in fuel consumption can be achieved.

[Third Embodiment]
Next, a third embodiment in which the present invention is embodied in another hybrid truck 1 control device will be described.
The control device for the hybrid truck 1 of the present embodiment also has the same overall configuration as that of the first embodiment, and the difference is that the motor 3 depends on whether or not the auxiliary machinery 2a is driven during coasting control. The purpose is to switch between driving the engine 2 and stopping the engine 2. Therefore, common constituent parts are denoted by the same member numbers, description thereof is omitted, and differences are mainly described.

  When the coast running control start condition is satisfied, a series of control procedures for starting the control described in the first embodiment is executed. Prior to the execution of this control procedure, in this embodiment, it is determined by the vehicle ECU 13 whether or not the auxiliary machinery 2a needs to be driven during coasting control (auxiliary drive necessity determination means). For example, when an air compressor is installed as one of the auxiliary machines 2a of the brake system, the air pressure of the air tank that stores the compressed air for operating the brake is compared with a specified value while the vehicle 1 is traveling, and the comparison result Based on the above, the air compressor is appropriately operated to replenish the air tank with the compressed air.

  When the coasting control start condition is satisfied, if the air pressure in the air tank has dropped to a specified value, it is determined that the air compressor needs to be driven during coasting control. If the air pressure in the air tank is sufficiently higher than the specified value, it is determined that driving of the air compressor is unnecessary during coasting control. With respect to the other auxiliary machines 2a, the necessity determination of driving during coasting control is performed.

If the vehicle ECU 13 determines that any one of the auxiliary machines 2a needs to be driven, as described in the first embodiment, the vehicle ECU 13 drives the engine 2 by the motor 3 during the coasting control, and the auxiliary machine 2a. The operation of class 2a is continued. Further, when it is determined that driving of all the auxiliary machinery 2a is unnecessary, the vehicle ECU 13 cuts the fuel of the engine 2 and stops it without executing motor driving during coasting control. The stopped engine 2 may be started by driving the motor 3 with the end of the coasting control.
When the engine 2 is stopped during coasting control, the power consumption of the motor 3 for driving the engine can be reduced. Therefore, further improvement in fuel consumption can be achieved as compared with the first and second embodiments.

  On the other hand, whether or not the auxiliary machinery 2a needs to be driven during coasting control can be determined more accurately by using the road conditions acquired from the navigation device 31 and the communication device 32. For example, if a gentle downhill road is predicted ahead on the travel route of the vehicle based on the acquired road condition, and the downhill road is a curve, it can be estimated that steering is performed during coasting control. Therefore, the engine 2 is driven by the motor 3 so that the power steering pump which is one of the auxiliary machines 2a of the steering system is operated during the coasting control. Further, when the predicted downhill road is a straight road, it can be considered that steering is not substantially performed during coasting control. Therefore, it is not necessary to operate the power steering pump during coasting control, and the engine 2 may be stopped.

This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above embodiment, the present invention is applied to a hybrid truck, but may be applied to a hybrid bus or a passenger car.
Moreover, although the hybrid type truck 1 of the said embodiment connected the engine 2 and the motor 3 via the clutch 4, and connected the motor 3 to the drive wheel 9 side, the structure is not restricted to this. Absent. For example, the engine 2 and the motor 3 may be directly connected, and the motor 3 may be configured as a hybrid truck in which the motor 3 is connected to the drive wheel 9 via the clutch 4. When configured in this manner, the engine 2 and the motor 3 can be disconnected from the drive wheel 9 side by disconnection of the clutch 4. Therefore, instead of returning the transmission 5 to neutral during coasting control, the clutch 4 may be held in a disconnected state instead.

2 Engine 2a Auxiliary equipment 3 Motor 4 Clutch 9 Drive wheel 13 Vehicle ECU (Coast travel control means, Auxiliary drive necessity judgment means)

Claims (4)

When an engine and a motor are mounted as a driving source for traveling, and the auxiliary machines are driven by the engine, when the vehicle shifts to a specific traveling state as the accelerator pedal is turned off by the driver, In a hybrid vehicle control device that performs coast running control for coasting the vehicle by separating the engine and motor from the drive wheel side by coast running control means,
The coast running control means cuts the fuel of the engine during the coast running control, and drives the engine with the motor to maintain a preset rotational speed.   The coast running control means is configured to synchronize with the driving wheel side by raising a driving force of the motor and increasing a rotation speed of the engine when the coast running control is finished. The hybrid vehicle control device according to claim 1. Auxiliary machine drive necessity determination means for determining whether or not the auxiliary machines need to be driven during the coast running control is provided,
The coast driving control means drives the engine by the motor when the auxiliary drive necessity determining means determines that the auxiliary machines need to be driven, and the auxiliary drive necessity determining means determines the auxiliary machine. The hybrid vehicle control device according to claim 1 or 2, wherein when it is determined that a special type of drive is unnecessary, the engine is cut off and stopped without executing the drive by the motor.   4. The hybrid according to claim 1, wherein the coasting control means drives the engine by the motor at a rotation speed optimum for the operation of the auxiliary machines during the coasting control. Vehicle control device.

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