JP6098037B2 - Hybrid vehicle - Google Patents

Description

  The present invention relates to a hybrid vehicle including an engine and an electric motor as a driving source for driving the vehicle.

  In a hybrid vehicle including an engine and a motor generator as a travel drive source, regenerative power generation is performed in which rotational energy of a drive shaft is converted into electric energy by a motor generator and stored in a battery during deceleration or braking.

  By the way, in general, a vehicle is equipped with auxiliary machines such as a power steering and an air conditioner, and these auxiliary machines are driven by the driving force of the engine. For this reason, when the hybrid vehicle is running with the driving force of the motor generator, in order to maintain the driving of these auxiliary machines, the engine is idled or the clutch is connected and the driving force of the motor generator is used. It is necessary to rotate the engine.

  For example, Patent Document 1 discloses a technique for driving an auxiliary machine by an engine in a hybrid vehicle, while driving the auxiliary machine by rotating a crankshaft by a traveling motor generator when the engine is stopped. Has been.

JP-A-9-289706

  By the way, when the vehicle is traveling, the driver may perform a small accelerator operation for speed adjustment during deceleration such as when the engine brake is operated. In particular, when the engine speed is high and the fuel injection amount is small, the engine is driven in an operation region where the engine efficiency is low, resulting in a deterioration in fuel consumption.

  Further, when the vehicle is running with the driving force of the motor generator and the engine is idling to maintain the driving of the auxiliary machinery, the fuel consumption is deteriorated by the amount of idle fuel injection. Further, when the engine is rotated by the driving force of the motor generator in order to maintain the driving of the accessories when the engine is stopped as in the above-described conventional technology, the efficiency may be reduced due to engine friction. .

  The present invention has been made in view of such a point, and an object thereof is to effectively suppress deterioration in fuel consumption and reduction in efficiency without stopping the driving of auxiliary machinery when the vehicle is decelerated. is there.

  In order to achieve the above object, a hybrid vehicle of the present invention is a hybrid vehicle including an engine and an electric motor as a driving source for driving the vehicle, and includes a generator driven by the engine and a running state of the vehicle. Deceleration determining means for determining whether or not the vehicle is decelerating and a predetermined low load region in which the required load for the driving source for traveling is higher when the electric motor is used than when the engine is used as a driving source And a control means for controlling the fuel injection of the engine, the drive of the electric motor, and the drive of the generator, and the deceleration determination means determines that the vehicle is decelerating. And when the required load determining means determines that the required load is in a predetermined low load region, the control means performs fuel injection of the engine and power generation drive of the generator. Causes locked, characterized in that to drive the electric motor as a travel drive source.

  Further, the required load is an instruction fuel injection amount to the engine which is converted from a depression amount of an accelerator pedal operated by an operator, and the required load determination means is more than the engine as a drive source. A fuel injection amount threshold value that is more efficient when an electric motor is used is set for each engine speed, and when the converted command injection amount is equal to or less than the threshold value, the required load is set to a predetermined low load region. It may also be determined that

  And a variable displacement supercharger including variable blades provided in a turbine driven by exhaust of the engine, wherein the control means further controls an opening degree of the variable blades, and the deceleration determination means Is determined to be decelerating, and when the required load determining means determines that the required load is in a predetermined low load region, the control means further reduces the opening of the variable blades to reduce friction of the engine. The predetermined opening may be controlled.

  In addition, the predetermined opening degree of the variable blade that reduces the friction of the engine may be set to increase as the engine speed increases.

  And an exhaust gas recirculation device including a flow rate adjustment valve provided in a flow path connecting the exhaust system and the intake system of the engine, and the control means further controls the opening of the flow rate adjustment valve, When the deceleration determining means determines that the vehicle is decelerating and the required load determining means determines that the required load is in a predetermined low load region, the control means further sets the opening of the flow rate adjusting valve to the engine. The opening may be controlled to a predetermined opening that reduces the friction.

  Further, the predetermined opening degree of the flow rate adjusting valve for reducing the friction of the engine may be set so as to decrease as the engine speed increases.

  According to the hybrid vehicle of the present invention, at the time of deceleration of the vehicle, it is possible to effectively suppress the deterioration of the fuel consumption and the decrease in efficiency without stopping the driving of the auxiliary machinery.

1 is a schematic overall configuration diagram showing a hybrid vehicle according to a first embodiment of the present invention. It is a functional block diagram showing ECU concerning a first embodiment of the present invention. It is a figure which shows the injection quantity threshold value map which concerns on 1st embodiment of this invention. It is a flowchart which shows the control content which concerns on 1st embodiment of this invention. It is a functional block diagram which shows ECU which concerns on 2nd embodiment of this invention. It is a figure which shows the opening degree setting map which concerns on 2nd embodiment of this invention. It is a flowchart which shows the control content which concerns on 2nd embodiment of this invention.

  Hereinafter, embodiments of a hybrid vehicle according to the present invention will be described with reference to the drawings.

[First embodiment]
Based on FIGS. 1-4, the hybrid vehicle which concerns on 1st embodiment of this invention is demonstrated. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  As shown in FIG. 1, a hybrid vehicle 1 according to the present embodiment includes a diesel engine (hereinafter simply referred to as an engine) 10 having a plurality of cylinders, and a transmission 12 connected to the engine 10 via a main clutch 11. A motor generator 13 driven as an electric motor or a generator, an inverter 14 electrically connected to the motor generator 13, a main battery 15 electrically connected to the inverter 14, and the devices 10 to 15 are controlled. An electronic control unit (hereinafter referred to as ECU) 40, a propeller shaft 17 connected to the transmission 12, a differential device 18 connected to the propeller shaft 17, and a differential device 18 are connected via a drive shaft 19. Left and right drive wheels 31L, 31R, a vehicle speed sensor 61 for detecting the speed of the vehicle 1, and the engine 10 An engine speed sensor 62 for detecting the rotation number, and a accelerator position sensor 63 that detects the depression amount of the accelerator pedal 30 by the operator.

  An intake passage 22 is connected to the intake manifold 20 of the engine 10. An exhaust passage 23 is connected to the exhaust manifold 21 of the engine 10. Further, the engine 10 includes a variable capacity turbocharger (supercharger) 24, an EGR device (exhaust gas recirculation device) 25 that circulates part of the exhaust gas to the intake system, and an alternator (generator) that is driven by the engine 10. 26).

  The turbocharger 24 is a known VGT (Variable Geometry Turbo), and includes a compressor 24a provided in the intake passage 22, a turbine 24b provided in the exhaust passage 23, and variable blades 24c provided in the turbine 24b. ing. The compressor 24a and the turbine 24b are connected via a rotating shaft. Further, the turbocharger 24 is provided with an actuator (not shown) that opens and closes the variable blade 24c in accordance with an instruction signal input from the ECU 40.

  The EGR device 25 includes an EGR passage 25a that connects the exhaust passage 23 and the intake manifold 20, an EGR valve (flow rate adjusting valve) 25b provided in the EGR passage 25a, an EGR cooler (not shown) provided in the EGR passage 25a, It has. The exhaust gas flow rate by the EGR device 25 is adjusted by controlling the opening degree of the EGR valve 25b in accordance with an instruction signal input from the ECU 40.

  The rotating force of the crank pulley 10b connected to the crankshaft 10a is transmitted to the alternator 26 via the belt 26a. The electric power generated by the alternator 26 is used to drive auxiliary machinery of the engine 10 (not shown), and surplus power is stored in the sub-battery 27. The alternator 26 includes a rotor coil and a stator coil (not shown), and the supply of excitation current to the rotor coil is controlled to be ON / OFF according to an instruction signal input from the ECU 40. It is switched to the power generation drive state or the power generation stop state.

  The main clutch 11 is, for example, a wet multi-plate clutch, and controls connection / disconnection of the crankshaft 10 a of the engine 10 and the input shaft 12 a of the transmission 12. The connection / disconnection control by the main clutch 11 is performed by operating a clutch actuator (not shown) according to an instruction signal input from the ECU 40.

  The transmission 12 is provided on an input shaft 12a connected to the main clutch 11, an output shaft (not shown) connected to the propeller shaft 17, a counter shaft (not shown) parallel to the input shaft 12a and the output shaft, and these shafts. And a plurality of gears (not shown). Further, a PTO shaft 30 constituting a part of a power take-out device (hereinafter referred to as a PTO device) is connected to the output shaft of the transmission 12 via a gear (not shown). The speed change operation of the transmission 12 is automatically controlled according to an instruction signal input from the ECU 40.

  A rotation shaft (not shown) of the motor generator 13 is connected to the PTO shaft 30 of the PTO device. The motor generator 13 is driven as a motor when DC power stored in the main battery 15 is converted into AC power by an inverter 14 and supplied. The motor generator 13 is driven as a generator by being rotated in conjunction with an output shaft (not shown) of the transmission 12 during regenerative braking. The PTO shaft 30 may be provided with a PTO clutch (not shown) that is connected / disconnected in accordance with an instruction signal input from the ECU 40.

  Inverter 14 controls electric power between motor generator 13 and main battery 15 in accordance with an instruction signal input from ECU 40. For example, when the motor generator 13 is driven as a motor, the inverter 14 converts DC power stored in the main battery 15 into predetermined AC power and supplies it to the motor generator 13. Further, when the motor generator 13 is driven as a generator, the inverter 14 converts the AC power regenerated by the motor generator 13 into DC power and then supplies the DC power to the main battery 15.

  The ECU 40 controls various devices mounted on the vehicle 1 such as the engine 10 and the transmission 12, and includes a known CPU, ROM, RAM, input port, output port, and the like. In order to perform these various controls, the output signals of various sensors such as the vehicle speed sensor 61, the engine speed sensor 62, and the accelerator position sensor 63 are input to the ECU 40 after A / D conversion.

  Further, as shown in FIG. 2, the ECU 40 includes a deceleration determination unit 41, a minute injection determination unit 42, a required load determination unit 43, an engine control unit 45, an ACG control unit 46, and a travel motor drive control unit 49. As a part of functional elements. In the present embodiment, these functional elements are described as being included in the ECU 40, which is an integral piece of hardware. However, any one of these functional elements may be provided in separate hardware.

  The deceleration determination unit 41 determines whether the traveling state of the vehicle 1 is decelerating based on the vehicle speed V detected by the vehicle speed sensor 61. For example, if the change amount ΔV of the vehicle speed V is negative, the running state of the vehicle 1 is determined to be decelerating, and if the change amount ΔV of the vehicle speed V is positive, the running state of the vehicle 1 is determined to be accelerating. In the present embodiment, the deceleration determination unit 41 and the vehicle speed sensor 61 correspond to the deceleration determination means of the present invention.

  The minute injection determination unit 42 tends to decrease the command injection amount Q based on the fuel injection amount Q (hereinafter referred to as the command injection amount) Q converted from the depression amount of the accelerator pedal 30 detected by the accelerator position sensor 63. It is determined whether or not. For example, if the change amount ΔQ of the command injection amount Q is negative, it is determined that the command injection amount Q is decreasing. If the change amount ΔQ of the command injection amount Q is positive, the command injection amount Q is determined to be increasing. .

The required load determination unit 43 has a predetermined instruction amount Q calculated by the micro injection determination unit 42 that is more efficient when the motor generator 13 is used than when the engine 10 is used as a driving source for driving the vehicle 1. It is determined whether it is in the low load region. More specifically, the ECU 40 stores an injection amount threshold map (see FIG. 3) that uses the engine speed N and the commanded injection amount Q, which are created in advance through experiments or the like, as parameters. On this injection amount threshold map, there is set an injection amount threshold value Q _{TH in} which the command injection amount Q is increased as the engine speed N increases. In the injection quantity threshold on map, region A instructed injection amount Q becomes equal to or less than the injection quantity threshold value Q _TH is a predetermined low load better to use the motor generator 13 than with the engine 10 becomes the high efficiency as a traveling drive source Indicates the area. Further, the injection quantity threshold on map, region instructed injection amount Q is larger than the injection quantity threshold value Q _TH B is given the better to use the engine 10 than using the motor-generator 13 as a traveling drive source has a higher efficiency The high load area is shown.

The required load determination unit 43 reads the injection amount threshold value Q _TH corresponding to the engine speed N detected by the engine speed sensor 62 from the injection amount threshold map, and uses the injection amount threshold value Q _TH and the minute injection determination unit 42. The calculated latest commanded injection quantity Q is compared. When the most recent command injection amount Q is equal to or less than the injection amount threshold value Q _TH (Q ≦ Q _TH ), the required load determination unit 43 uses the command generator Q more efficiently than the engine 10 when the motor generator 13 is used. Is determined to be in a predetermined low load region. On the other hand, when the latest command injection amount Q is larger than the injection amount threshold value Q _TH (Q> Q _TH ), the required load determination unit 43 uses the command injection amount Q more efficiently than the motor generator 13. Is determined to be in a predetermined high load region. In the present embodiment, the minute injection determination unit 42, the required load determination unit 43, the engine speed sensor 62, and the accelerator position sensor 63 correspond to the required load determination unit of the present invention.

  The engine control unit 45 controls fuel injection by an injector (not shown) of the engine 10 according to the depression amount of the accelerator pedal 30 detected by the accelerator position sensor 63. Further, the engine control unit 45 determines that the deceleration determination unit 41 is decelerating the traveling state, the micro injection determination unit 42 determines that the command injection amount Q is in a decreasing tendency, and the required load determination unit 43 is the latest. Is determined to be in a predetermined low load region, the fuel injection by the injector is stopped.

  The ACG control unit 46 determines that the deceleration determination unit 41 is decelerating the traveling state, the micro injection determination unit 42 determines that the command injection amount Q is in a decreasing tendency, and the required load determination unit 43 indicates the latest instruction. When it is determined that the injection amount Q is in a predetermined low load region, the supply of excitation current to a rotor coil (not shown) of the alternator 26 is controlled from ON to OFF. That is, the alternator 26 is switched from the power generation drive state to the power generation stop state so that the friction of the engine 10 is reduced.

  The traveling motor drive control unit 49 controls driving of the motor generator 13 as an electric motor or a generator. Further, the traveling motor drive control unit 49 determines that the micro injection determination unit 42 determines that the command injection amount Q is in a decreasing tendency, and the request load determination unit 43 has the latest command injection amount Q in a predetermined low load region. When the determination is made, the motor generator 13 is supplied with predetermined power corresponding to the required load from the main battery 15 via the inverter 14. As a result, the motor generator 13 is driven as an electric motor for traveling, and the driving force is transmitted from the transmission 12 to the left and right drive wheels 31L and 31R via the propeller shaft 17, the differential device 18 and the drive shaft 19. The

  Next, based on FIG. 4, the control flow by ECU40 of the hybrid vehicle 1 which concerns on this embodiment is demonstrated. This control starts simultaneously with the start of the engine 10 (ignition switch key switch ON).

  In step (hereinafter, step is simply referred to as S) 100, the deceleration determination unit 41 determines whether or not the traveling state of the vehicle 1 is decelerating based on the change amount ΔV of the vehicle speed V. If the change amount ΔV is negative, it is determined that the traveling state of the vehicle 1 is decelerating, and the process proceeds to S110. On the other hand, when the traveling state of the vehicle 1 is not decelerating, the process returns to the deceleration determination of S100 again.

  In S110, the minute injection determination unit 42 determines whether or not the command injection amount Q is decreasing based on the command injection amount Q converted from the depression amount of the accelerator pedal 30. If the change amount ΔQ of the command injection amount Q is negative, the command injection amount Q is determined to be decreasing and the process proceeds to S120. On the other hand, when the command injection quantity Q is increasing, the process returns to S100.

In S120, the required load determination unit 43 determines whether or not the most recent command injection amount Q is in a predetermined low load region where the motor generator 13 is more efficient than the engine 10 as a drive source. The If the most recent command injection amount Q is equal to or less than the injection amount threshold value Q _TH read from the injection amount threshold map (Q ≦ Q _TH ), it is determined that the command injection amount Q is in a predetermined low load region, and the process proceeds to S130. . On the other hand, when the latest command injection amount Q is larger than the injection amount threshold value Q _TH (Q> Q _TH ), the process returns to S110.

  In S130, the motor generator 13 is driven as a motor for driving the vehicle by the travel motor drive control unit 49 while maintaining the main clutch 11 in the connected state. Further, in order to suppress the deterioration of fuel consumption, the engine control unit 45 stops the fuel injection of the engine 10 (injector). Further, in order to reduce the friction of the engine 10, the alternator 26 is switched to the power generation stop state by the ACG control unit 46.

  In S140, it is confirmed whether or not the command injection amount Q converted from the detected value of the accelerator position sensor 63 is zero. When the command injection amount Q is zero (Q = 0), this control is returned. On the other hand, when the command injection amount Q is not zero (Q ≠ 0), the process returns to S120. Thereafter, the control flow from S100 to S140 is repeated until the engine 10 stops (the key switch of the ignition switch is turned off).

  Next, the effect by the hybrid vehicle 1 which concerns on this embodiment is demonstrated.

  It is determined that the traveling state of the vehicle 1 is decelerating, the command injection amount Q is determined to be decreasing, and the command generator Q uses the motor generator 13 rather than the engine 10 as a travel drive source. When it is determined that the vehicle is in a predetermined low load region where the efficiency is high, the travel drive source is switched from the engine 10 to the motor generator 13 and fuel injection of the engine 10 is stopped.

  Therefore, fuel injection of the engine 10 is stopped in an operation region where the engine efficiency is reduced, such as when the driver performs a small accelerator operation for speed adjustment at the time of deceleration. Can be deterred.

  Further, when the motor generator 13 is driven as a motor for driving the vehicle, the main clutch 11 is maintained in a connected state in order to maintain driving of the auxiliary machinery. At this time, the alternator 26 is switched to the power generation stop state so that the friction of the engine 10 is reduced.

  Therefore, when the engine 10 is rotated by the driving force of the motor generator 13 to maintain the driving of the auxiliary machinery, the deterioration of the efficiency due to the engine friction is effectively suppressed by switching the alternator 26 to the power generation stop state. As a result, the traveling efficiency by the motor drive can be improved.

[Second Embodiment]
Hereinafter, based on FIGS. 5-7, 2nd embodiment of this invention is described.

  In the second embodiment of the present invention, as shown in FIG. 5, an opening setting control unit 47 is added as a functional element of the ECU 40 in the first embodiment described above. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  The opening setting control unit 47 controls the opening of the variable blade 24c and the opening of the EGR valve 25b so that the friction of the engine 10 is reduced. More specifically, the ECU 40 stores an opening degree setting map (see FIG. 6) showing the relationship between the engine speed N and the opening degrees of the variable blade 24c and the EGR valve 25b, which are created in advance through experiments or the like. On the opening setting map, the opening degree of the variable blade 24c increases as the engine speed N increases, while the opening degree of the EGR valve 25b decreases as the engine speed N increases.

  The opening setting control unit 47 determines that the deceleration determination unit 41 is decelerating the traveling state, the minute injection determination unit 42 determines that the command injection amount Q is in a decreasing tendency, and the required load determination unit 43 is the latest. When the determined injection quantity Q is determined to be in a predetermined low load region, the opening of the variable blade 24c and the opening of the EGR valve 25b corresponding to the engine speed N are read from the opening setting map, respectively. Control is performed so that the variable blade 24c and the EGR valve 25b are read.

  Next, based on FIG. 7, the control flow by ECU40 of the hybrid vehicle 1 which concerns on this embodiment is demonstrated. This control starts simultaneously with the start of the engine 10 (ignition switch key switch ON).

  In S200, the deceleration determination unit 41 determines whether the traveling state of the vehicle 1 is decelerating based on the change amount ΔV of the vehicle speed V. If the change amount ΔV is negative, it is determined that the traveling state of the vehicle 1 is decelerating, and the process proceeds to S210. On the other hand, when the traveling state of the vehicle 1 is not decelerating, the process returns to the deceleration determination of S200 again.

  In S210, the minute injection determination unit 42 determines whether or not the command injection amount Q is decreasing based on the command injection amount Q converted from the depression amount of the accelerator pedal 30. If the change amount ΔQ of the command injection amount Q is negative, the command injection amount Q is determined to be decreasing and the process proceeds to S220. On the other hand, when the command injection quantity Q is increasing, the process returns to S200.

In S220, the required load determination unit 43 determines whether or not the most recent command injection amount Q is in a predetermined low load region in which it is more efficient to use the motor generator 13 than to use the engine 10 as a drive source. The If the most recent command injection amount Q is equal to or less than the injection amount threshold value Q _TH read from the injection amount threshold map (Q ≦ Q _TH ), it is determined that the command injection amount Q is in the predetermined low load region, and the process proceeds to S230. . On the other hand, when the latest command injection amount Q is larger than the injection amount threshold value Q _TH (Q> Q _TH ), the process returns to S210.

  In S230, the motor generator 13 is driven as a motor for driving the vehicle by the travel motor drive control unit 49 while maintaining the main clutch 11 in the connected state. Further, in order to suppress the deterioration of fuel consumption, the engine control unit 45 stops the fuel injection of the engine 10 (injector). Further, in order to reduce the friction of the engine 10, the alternator 26 is switched to the power generation stop state by the ACG control unit 46. Further, in order to further reduce the friction of the engine 10, the opening setting control unit 47 controls the opening of the variable blade 24c and the opening of the EGR valve 25b to a predetermined opening.

  In S240, it is confirmed whether or not the command injection amount Q converted from the detected value of the accelerator position sensor 63 is zero. When the command injection amount Q is zero (Q = 0), this control is returned. On the other hand, when the command injection amount Q is not zero (Q ≠ 0), the process returns to S120. Thereafter, the control flow from S200 to S240 is repeatedly performed until the engine 10 is stopped (key switch OFF of the ignition switch).

  Next, the effect by the hybrid vehicle 1 which concerns on this embodiment is demonstrated.

  It is determined that the traveling state of the vehicle 1 is decelerating, the command injection amount Q is determined to be decreasing, and the command generator Q uses the motor generator 13 rather than the engine 10 as a travel drive source. When it is determined that the vehicle is in a predetermined low load region where the efficiency is high, the travel drive source is switched from the engine 10 to the motor generator 13 and fuel injection of the engine 10 is stopped.

  Therefore, fuel injection of the engine 10 is stopped in an operation region where the engine efficiency is reduced, such as when the driver performs a small accelerator operation for speed adjustment at the time of deceleration. Can be deterred.

  Further, when the motor generator 13 is driven as a motor for driving the vehicle, the main clutch 11 is maintained in a connected state in order to maintain driving of the auxiliary machinery. At this time, the alternator 26 is switched to the power generation stop state so that the friction of the engine 10 is reduced. Furthermore, the opening degree of the variable blade 24c and the EGR valve 25b is controlled to a predetermined opening degree that can reduce the friction of the engine 10.

  Therefore, when the engine 10 is rotated by the driving force of the motor generator 13 to maintain the driving of the auxiliary machinery, the alternator 26 is switched to the power generation stop state, and the engine friction can be reduced between the variable blade 24c and the EGR valve 25b. By controlling to a predetermined opening degree, it is possible to reliably suppress the deterioration of efficiency due to engine friction, and as a result, it is possible to reliably improve the efficiency of traveling by motor drive.

  The present invention is not limited to the above-described embodiments, and can be appropriately modified and implemented without departing from the spirit of the present invention.

  For example, the motor generator 13 has been described on the assumption that its rotating shaft is connected to the output shaft of the transmission 12 via the PTO shaft 30 of the PTO device, but is interposed between the main clutch 11 and the transmission 12. May be.

  Further, the engine 10 is not limited to a diesel engine, and can be widely applied to a gasoline engine or the like.

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 10 Engine 11 Main clutch 12 Transmission 13 Motor generator (electric motor)
14 Inverter 15 Main battery 24 Turbocharger (supercharger)
24b Turbine 24c Variable blade 25 EGR device (exhaust gas recirculation device)
25b EGR valve (Flow adjustment valve)
26 Alternator (generator)
40 ECU (control means)
DESCRIPTION OF SYMBOLS 41 Deceleration determination part 42 Micro injection | emission determination part 43 Required load determination part 45 Engine control part 46 ACG control part 47 Aperture setting control part 49 Traveling motor drive control part 61 Vehicle speed sensor 62 Engine speed sensor 63 Accelerator position sensor

Claims (5)

A hybrid vehicle including an engine and an electric motor as a driving source for driving the vehicle,
A generator driven by the engine;
Deceleration determination means for determining whether the vehicle is decelerating from the running state of the vehicle;
Required load determination means for determining whether the required load for the driving source for traveling is in a predetermined low load region where the electric motor is used more efficiently than when the engine is used as a drive source;
Control means for controlling fuel injection of the engine, driving of the electric motor, and driving of the generator;
When the deceleration determination means determines that the vehicle is decelerating and the required load determination means determines that the required load is in a predetermined low load region,
The control means stops fuel injection of the engine and power generation drive of the generator, and drives the electric motor as a driving source for traveling ,
The required load is a commanded fuel injection amount to the engine converted from an accelerator pedal depression amount operated by an operator,
The required load determination means sets a fuel injection amount threshold value that is more efficient when the electric motor is used than when the engine is used as a drive source according to the engine speed, and the converted instruction. When the injection amount is equal to or less than the threshold, it is determined that the required load is in a predetermined low load region,
The hybrid vehicle according to claim 1, wherein the required load determining means sets the threshold value that increases as the engine speed increases . A variable displacement supercharger including variable blades provided in a turbine driven by exhaust of the engine;
The control means further controls the opening of the variable wing,
When the deceleration determination means determines that the vehicle is decelerating and the required load determination means determines that the required load is in a predetermined low load region,
The hybrid vehicle according to claim 1 , wherein the control means further controls the opening of the variable blade to a predetermined opening that reduces friction of the engine. The hybrid vehicle according to claim 2 , wherein the predetermined opening degree of the variable wing at which the friction of the engine is reduced is set to increase as the engine speed increases. An exhaust gas recirculation device including a flow rate adjusting valve provided in a flow path connecting the exhaust system and the intake system of the engine;
The control means further controls the opening of the flow rate adjustment valve,
When the deceleration determination means determines that the vehicle is decelerating and the required load determination means determines that the required load is in a predetermined low load region,
The hybrid vehicle according to any one of claims 1 to 3 , wherein the control means further controls the opening of the flow rate adjusting valve to a predetermined opening that reduces friction of the engine. 5. The hybrid vehicle according to claim 4 , wherein the predetermined opening degree of the flow rate adjustment valve at which the friction of the engine is reduced is set so as to become smaller as the engine speed increases.