DE102013220343A1 - Series hybrid vehicle - Google Patents

Abstract

A series hybrid vehicle is provided with an engine control section that adjusts a power generation amount (charge) to be a power generation amount (charge) with which an engine driving state is an operating condition for performing system diagnosis, and a power generation amount (charge) that can be charged when the SOC falls to or below a preset predetermined value during a drive cycle at that time (since the key switch is turned ON at that time until the key switch is turned OFF the next time), and a control section that diagnoses faults without reducing power generation (charging) efficiency. A fault diagnosis can thus be performed with an accuracy as high as the accuracy obtained by a gasoline-powered vehicle in the prior art without reducing the power generation (charge) efficiency or reducing the possibilities of a fault diagnosis to reduce.

Description

Background of the invention

1. Field of the invention

The present invention relates to a series hybrid vehicle installed with an engine and a drive motor, and more particularly, to an apparatus that performs an engine control of a series hybrid vehicle using an engine only for power generation.

2. Description of the Related Art

As described in PTL 1, there is a series hybrid vehicle that uses a drive motor to drive the vehicle and an engine just to drive a power generator. The series hybrid vehicle achieves improvement in fuel efficiency and driving performance at the same time by controlling the engine in three drive (power generation) modes, which are switched from one to another according to a state of charge (hereinafter referred to as SOC) of the battery as follows , When the SOC is low, the engine is switched to a mode in which the engine is driven to generate power (hereinafter referred to as the forced power generation mode). When the SOC is high, the engine is switched to a mode in which the engine is stopped to generate no power (hereinafter referred to as the EV drive mode). When the state of charge is in the middle range, and neither of the above two modes is set, the engine is switched to a mode in which the engine is driven according to an operation amount on the accelerator and a vehicle speed to a power generation amount (hereinafter referred to as the vehicle speed association mode).

List of patent literature

• PTL 1: JP-A-2012-144138

Unlike a prior art gasoline powered vehicle, the series hybrid vehicle aims at providing a required power to the battery or the drive motor according to the SOC and a driving state of the vehicle without directly using the engine to drive the vehicle. Specifically, in the series hybrid vehicle, the engine is driven independently of an actual operation by the driver (operating condition of the vehicle), and a power generation amount is determined by a power of the power generator, i. an engine speed determined. A driving state of the engine can thus be maintained to generate energy efficiently.

On the other hand, the series hybrid vehicle requires an on-board diagnostic (OBD) to diagnose a power loss and electrical malfunction of various sensors and various actuators connected to an engine control device, for example, malfunctions including electrical isolation between a sensor and the engine control device , Fault diagnostic elements include elements for which a fault diagnosis is performed while the engine is in a predetermined drive state. Examples of such elements are fault diagnoses on an air-fuel ratio sensor (O ₂ sensor), which measures an air-fuel ratio of an exhaust gas.

Of the fault diagnoses on the air-fuel ratio sensor, a fault diagnosis for detecting an age-related deterioration of the sensor is the detection of an age-related drop in the power of the sensor. In this regard, a mixed state is changed from high to low and vice versa by increasing a fuel injection amount so that an oxygen amount in the exhaust gas varies, and a degree of the sensor's age-related power loss is checked by checking a subsequent oxygen concentration amount detected by the air Fuel ratio sensor is detected, checked. In order to diagnose a degree of the deterioration of the sensor due to age with accuracy, it is necessary to keep a time constant because a fuel injection amount is increased or decreased until an actual amount of oxygen in the exhaust gas varies. In other words, it is necessary to detect the deterioration of the sensor due to age, while the driving state of the engine satisfies predetermined operating conditions with respect to an air intake amount, an engine speed, and so forth.

In PTL 1, the drive (power generation) mode is switched to an appropriate one according to the SOC. In particular, the vehicle speed association mode performs mimic of the engine drive of a gasoline-powered vehicle. However, the drive (power generation) mode drops out of the vehicle speed association mode when the SOC rises or falls, and is put into the EV drive mode or the forced Power generation mode switched by the engine speed is kept constant.

A fault diagnosis is not performed in the EV drive mode because the engine is stopped. A priority is also directed to engine control, which emphasizes power generation efficiency and fuel economy in the forced power generation mode. The driving state of the engine thus can not satisfy the condition under which a failure diagnosis for detecting an age-related power loss of the sensor is performed.

The series hybrid vehicle thus has less possibility of fault diagnosis by the engine control device as compared with the prior art gasoline powered vehicle. Moreover, if charging is to some extent (the SOC is high), the series hybrid vehicle may drive the vehicle using the drive motor while the engine is stopped until the SOC reaches a target engine start value (target value). SOC value at which power generation (charge) is started by starting the engine when the SOC drops and power for driving the drive motor becomes scarce). These features reduce the chances of fault diagnosis by the engine control device.

In the vehicle speed association mode, the engine is driven in accordance with an operation amount on the accelerator at a vehicle speed. Thus, an error may be diagnosed when the driving state of the engine satisfies the condition under which a failure diagnosis is performed for detecting an age-related drop in the power of the sensor. However, the frequency of fault diagnosis is reduced as the SOC varies and the mode is switched to another mode, i. in the EV running mode or the forced power generation mode, or when an engine speed changes with a variance of the driving state of the engine and the engine driving state no longer satisfies the condition under which a failure diagnosis for detecting an age-related power drop of the sensor is performed. The frequency of the fault diagnosis may be increased by extending a range of the condition under which a fault diagnosis is performed for detecting an age-related drop in the power of the sensor (for example, by extending a range of engine speed at which fault diagnosis is performed). However, the amplitude of a time since a fuel injection amount is increased or decreased until an actual amount of oxygen in the exhaust gas varies is increased in this case. Such a rise results in a problem that an error can not be detected with an accuracy as high as the accuracy by the prior art gasoline-powered vehicle with respect to a degree of the sensor's power loss is obtained.

Summary of the invention

The invention aims at solving the problems discussed above, and has for its object the provision of a series hybrid vehicle equipped with an engine control device capable of performing a fault diagnosis with an accuracy as high as that of the gasoline powered one Vehicle is obtained in the prior art, without deteriorating a power generation (charging) behavior or to reduce the possibilities of fault diagnosis of the hybrid vehicle.

A series hybrid vehicle according to one aspect of the invention includes: an engine; a power generator powered by the engine; a battery charged by the power generator; a drive motor that drives wheels with energy generated by the power generator or power discharged from the battery; and an engine control device that controls the engine. The engine control device is configured with: a function for detecting a state of charge of the battery; an engine start-up function for starting the engine when the detected state of charge of the battery drops to a predetermined value; a failure diagnosis start determination function for starting a power supply to the battery and the drive motor by the power generator, by starting the engine using the engine startup function, and determining a start of a failure diagnosis when the state of charge of the battery is at a predetermined value increases; and a function for starting a fault diagnosis when the start of the fault diagnosis is determined by the fault diagnosis start determining function.

The above and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

Brief description of the drawings

1 FIG. 14 is a view illustrating a drive system of a series hybrid vehicle according to a first embodiment of the invention; FIG.

2 FIG. 10 is a view of a behavior of the SOC starting from a state in which a battery is sufficiently charged by an operation of an engine control device that performs a failure diagnosis of the first embodiment; FIG.

3 FIG. 10 is a flowchart showing an operation of the engine control apparatus that performs a failure diagnosis of the first embodiment; FIG.

4 FIG. 10 is a flowchart showing a processing procedure for starting an engine according to the embodiment of the invention; FIG.

5 FIG. 10 is a flowchart showing a processing procedure for starting a fault diagnosis according to the embodiment of the invention; FIG.

6 Fig. 10 is a flowchart showing a processing procedure for terminating a fault diagnosis according to the embodiment of the invention;

7 FIG. 10 is a flowchart for determining a content of a failure diagnosis according to the SOC in a failure diagnosis according to the embodiment of the invention; FIG.

8th FIG. 15 is a view of a behavior when the SOC rises while performing a fault diagnosis according to a second embodiment of the invention; FIG. and

9 FIG. 12 is a view of a behavior when the SOC drops while performing a fault diagnosis according to the second embodiment of the invention. FIG.

Detailed description of the invention

First embodiment

1 FIG. 12 is a block diagram illustrating a drive system configuration of a series hybrid vehicle of the invention. FIG. A drive system of the series hybrid vehicle includes an engine 1 , an energy generator or power generator 3 powered by the engine, a battery 4 Power charged by the power generator, a drive motor 5 which rotates when using this power from the power generator 3 and the battery 4 is supplied, a wheel that comes from a left front wheel 6L and a right front wheel 6R is formed, both with the drive motor 5 coupled, an engine control device 2 for controlling the engine 1 and a vehicle control device 7 which controls the entire drive of the vehicle.

3 FIG. 10 is a flowchart for illustrating an operation of the engine control device. FIG 2 , which performs a fault diagnosis according to the embodiment of the invention. 2 shows a behavior of the SOC when a fault diagnosis is performed. The Y axis is used for the SOC (%) and the X axis is used for a time. Greek letters α, β, and γ in 2 denotes level determination values of the SOC. 4 FIG. 10 is a flowchart of the engine control device. FIG 2 when it is determined whether the engine according to the SOC of the battery 4 to start or not. 5 FIG. 10 is a flowchart of the engine control device. FIG 2 if according to the SOC of the battery 4 It is determined whether to perform a fault diagnosis or not. 6 FIG. 10 is a flowchart of the engine control device. FIG 2 when it is determined whether or not all the trouble diagnoses have been completed by performing the fault diagnoses.

An operation of the engine control device 2 according to the first embodiment of the invention will be described below with reference to a behavior of the SOC according to 2 and the flowcharts according to 3 to 6 explained. This operation is performed by the engine control device 2 at regular time intervals of, for example, every ten msec.

4 FIG. 10 is a flowchart of an operation of the engine control device. FIG 2 if according to the SOC of the battery 4 it is determined if the engine 1 to start or not. Referring to 4 becomes an operation of the engine control device 2 explains when the operation starts in a state where the engine 1 stopped (engine stop). In the beginning it is determined if the engine 1 already started (step S41). Since the engine is stopped (ie, NO), it is determined here whether the SOC is below the in 2 shown determination value α is (SOC> determination value α).

When it is determined in step S45 that the SOC is below the determination value α (ie, YES), the engine control device starts 2 the engine 1 (Engine startup) (Step S46).

Referring to 4 Hereinafter, an operation of the engine control device will be explained 2 explains when the operation starts in a state where the engine 1 already started (engine commissioning). Since it is determined in step S41 that the engine 1 is already started (ie, YES), it is initially determined whether the SOC is the in 2 shown determination value γ (determination value α> determination value γ) exceeds (SOC> γ) (step S42).

When it is determined in step S42 that the SOC exceeds the determination value γ (ie, YES), the engine control device stops 2 the engine 1 (Step S43). In subsequent step S44, the vehicle travels by the drive motor 5 alone using the battery 4 a power or current is supplied.

5 FIG. 10 is a flowchart for illustrating an operation of the engine control device. FIG 2 when it is determined according to the SOC whether to perform a fault diagnosis or not. Referring to 5 becomes an operation of the engine control device 2 explains when the operation starts in a state where the engine 1 already started (engine commissioning). Because the engine 1 is already started in step S51 (ie, YES), it is initially determined whether the SOC is equal to or greater than that in 2 shown determination value β (determination value α <determination value β <determination value γ) is (SOC ≥ β) (step S52).

When it is determined in step S52 that the SOC is equal to or greater than the determination value β (ie, YES), the engine control apparatus allows 2 in that a fault diagnosis is carried out (step S53). On the other hand, when it is determined that the SOC is smaller than the determination value β (ie, NO), the engine control device performs 2 no process through, but stops the operation.

Referring to 5 Hereinafter, an operation of the engine control device will be explained 2 explains when the operation starts in a state where the engine 1 stopped (engine stop). Because the engine 1 is stopped (ie, NO) in S51, suppresses the engine control device 2 in that a fault diagnosis is performed (step S54).

6 FIG. 10 is a flowchart of the engine control device. FIG 2 when it is determined whether or not all error diagnoses have been completed by performing fault diagnoses. Referring to 6 Hereinafter, an operation of the engine control device will be explained 2 when the operation starts in a state where not all of the trouble diagnoses for detecting age-related deterioration of various sensors (hereinafter referred to as system failure diagnoses) are completed. Since not all system failure diagnoses are completed in step S61 (ie, NO), the engine control device performs 2 Initially, system failure diagnoses of the respective sensors are performed (step S63).

There will now be an operation of the engine control device 2 Explains when the operation starts in a state in which all system error diagnoses of various sensors are completed. Since all system failure diagnoses are completed in step S61 (ie, YES), the engine control apparatus determines 2 Initially, the initial system failure diagnostics are completed (step S62).

An operation of the engine control device 2 according to this embodiment of the invention will now be described with reference to the contents of 4 to 6 , the behavior of the SOC, shown in 2 , and the flowchart according to 3 explained.

Referring to 2 becomes an operation of the engine control device 2 explains when the operation starts in a state where the SOC of the battery 4 is high (the battery 4 is sufficiently charged), that is, when the operation starts in the EV drive mode. Since the SOC is high, the engine is 1 initially in an engine stop state in step S31 in FIG 3 (ie NO). The engine control device 2 thus performs a normal power generation control (step S35). The EV propulsion mode, in which a power is generated, continues here.

The SOC decreases with the lapse of time, and the engine is started (step S46) when the SOC falls to or below the determination value α with a lapse of time at time T21 (ie, YES in step S45). In this case, the engine startup is determined in step S31 (ie, YES). The engine control device 2 thus determines whether it is allowed that a failure diagnosis can be performed in the following step (step S32).

Subsequently, the energy generator or power generator 3 driven, since the engine startup is determined, and the SOC increases when the battery 4 through the energy producer 3 is charged. Finally, the SOC increases to or exceeds the determination value β (YES in step S52), with a timing at time T22. A fault diagnosis can then be performed (step S53). In this case, since a failure diagnosis is permitted in step S32 (ie, YES), the engine control device determines 2 Whether the following initial fault diagnosis is completed or not (step S33).

Since it is determined in step S33 that the initial failure diagnoses are not completed (step S63) immediately after being allowed to perform a fault diagnosis (ie, YES), the engine control device performs 2 a fault diagnosis. On the other hand, if it is determined in step S33 that the initial error diagnoses are completed with the timing (ie, NO) (YES in step S61), it is determined that the initial failure diagnoses have been completed (step S62). The engine control device 2 therefore, performs normal power generation control (step S35) (performs either the forced power generation mode or the vehicle speed association mode in response to a state of the SOC), and performs a fault diagnosis when the engine drive state satisfies the condition under which fault diagnosis is performed ,

In the following, it will be an adaptation of a size of the power generation (charge) of the energy generator or power generator 3 regarding 2 explained while a fault diagnosis is being performed. A behavior of the SOC while a fault diagnosis is performed is one after a timing at the time T22. The vehicle control device 2 calculates a power generation quantity that the battery uses 4 can be charged based on an energy or power to drive the drive motor 5 is required (hereinafter referred to as a discharge size) and a state of the SOC. The vehicle control device 7 then sends the thus calculated power generation amount to the engine control device 2 , via a bus satisfying the standard such as Controller Area Network (CAN) (not shown) as information regarding a required power generation amount.

The engine control device 2 determines a discharge amount of the vehicle based on a required power generation amount (charge) and a change in the state of the SOC from time T21 to time T22. The SOC does not further vary when the discharge size thus determined and one from the engine 1 output power generation amount (charge) are set to the same value.

The engine control device 2 sets a power generation amount having a value equal to or close to the required engine power generation amount based on a used power generation amount (charge) as a condition under which the system failure diagnoses of the respective sensors may be performed as a final engine power generation amount (Charge) (hereinafter referred to as the engine power generation target). The engine control device 2 then controls a power generation quantity of the power generator 3 so that it agrees with the engine power generation target by an air intake amount of the engine 1 is adjusted using a throttle valve (not shown).

Subsequently, the engine control device estimates 2 a discharge amount of the vehicle in response to a variance of the SOC at the time T22 and thereafter, and sets the required engine power generation amount based on the estimated value. The engine control device 2 calculates the engine generation target on the basis of the thus set required engine power generation amount, in the same manner as explained in the previous section, and controls the engine 1 ,

Since the engine control device 2 the engine 1 according to the engine power generation target size, the SOC varies in the vicinity of the determination value β, at the time T22 and after. It is thus possible to perform a system failure diagnosis without causing a drop in the SOC.

By performing system failure diagnosis during power generation (charging) by starting the engine, according to the first embodiment, the possibilities for performing fault diagnosis are not limited. Further, by determining a discharging amount for the vehicle and performing a fault diagnosis in an engine driving state where a power generation amount (charge) is made comparable to the discharging amount, it is possible to perform a fault diagnosis with an accuracy as high as the accuracy achieved by a gasoline powered vehicle is obtained in the prior art, without the efficiency of the power generation (charge) is deteriorated.

Second embodiment

A vehicle system configuration of a second embodiment is the same as that of FIG 1 , The operation of the engine control device 2 differs from the counterpart of the above first embodiment. In the above first embodiment, the SOC may possibly vary when a discharge amount of the vehicle particularly varies with operation of the accelerator during a system failure diagnosis. In this case, the controller can not work in the vicinity of the determination value β, and the SOC becomes either SOC <determination value α or SOC> determination value γ, and the efficiency of power generation (charge) possibly deteriorates. The second embodiment relates to an operation of the engine control device 2 in this case, these being referred to below with reference to 7 to 9 is explained.

7 FIG. 10 is a flowchart of the engine control device. FIG 2 when determining elements for which a fault diagnosis is performed in response to a variance of the SOC. 8th Fig. 10 shows a behavior of the SOC when a discharge amount is reduced by an operation on the accelerator pedal (the engine power generation target amount is decreased). 9 Fig. 10 shows a behavior of the SOC when a discharge amount increases by operation on the accelerator (the target of engine power generation increases). In 8th and 9 the Y coordinate is used for the SOC (%), and the X axis is used for a time. Greek letters α, ε, β, δ, and γ are moreover determination values of the SOC. A variance of the SOC will be described below with reference to the behavior of the SOC 8th and 9 and the flowchart according to 7 explained.

When a discharge amount of the vehicle increases (the target of engine power generation decreases) at time T81 of FIG 8th , the rise of SOC begins, as shown at and after T81. In addition, when a discharge amount of the vehicle at the time T91 in FIG 9 increases (the target of engine power generation increases), a fall in SOC begins, as shown at and after time T91.

Regarding 7 In the following, the flowchart of the engine control device will be described 2 explains when switching to fault diagnosis items in response to a variance of the SOC, as in FIG 8th and 9 shown. This operation is performed by the engine control device 2 at regular time intervals of, for example, every 10 msec.

Referring to 7 Hereinafter, an operation of the engine control device will be explained 2 explains when the operation starts in a state in which the execution of a fault diagnosis is allowed (step S53). Since this is a state in which the execution of a fault diagnosis in step S71 (ie, YES) is allowed, a continuation is made in subsequent step S72.

After a time has elapsed until time T81 of 8th and if it is determined in step S72 that this is a state in which the SOC is greater than the determination value ε (determination value α <determination value ε <determination value β) (SOC> determination value ε) (ie NO) and determined in subsequent step S74 is that this is a state in which the SOC is less than the determination value δ (determination value β <determination value δ <determination value γ) (SOC <determination value δ) (ie, NO), this means that the SOC does not vary and remains stable. The engine control device 2 therefore performs a fault diagnosis normally, ie, performs fault diagnosis according to the predetermined order (step S76).

If subsequently at time T82 according to 8th In step S72, it is determined that this is a state in which the SOC is greater than the determination value ε (SOC> determination value ε) (ie, NO), and it is determined in the subsequent step S74 that this is a state in which the SOC SOC is larger than the determination value δ (SOC> determination value δ) (ie, YES), it is determined that the SOC is increasing. The engine control device 2 therefore, performs, with a high priority, a diagnosis item having a large power consumption (step S75) as a diagnosis item to be performed next after the currently performed fault diagnosis is completed. Examples of a diagnostic element having a large power consumption include the air-fuel ratio sensor (not shown). It is necessary for the air-fuel ratio sensor to be activated by raising a temperature of the sensor itself before a diagnosis. Thus, in order to perform a fault diagnosis on the air-fuel ratio sensor, it is necessary to consume energy by driving a heater and driving solenoids of an oil control valve (not shown) to provide a valve timing for a variable valve timing mechanism (not shown). and a bleed valve (not shown) to supply the engine with evaporated fuel gas generated in the fuel tank.

Due to the behavior in step S75, the power consumption increases and the SOC starts to decrease in a manner as shown at and after time T83. In this case, when the SOC is less than the determination value δ (SOC <determination value δ) (a state when the determination in step S74 is NO), the engine control device performs 2 a fault diagnosis to be performed next, normally, after the currently performed fault diagnosis is completed, ie, performs a diagnosis according to the predetermined order (step S76).

Finally, the SOC goes to a state where the SOC is less than the determination value ε (determination value α <determination value ε <determination value β) (SOC <determination value ε) (ie, YES) at time T92 in FIG 9 , It is thus determined in step S72 that the SOC is decreasing. Elements of fault diagnosis to be performed next after the currently performed fault diagnosis is completed are thus diagnostic items having low power consumption (step S73), for example, a temperature of engine cooling water (not shown). For this diagnostic element, only a temperature of engine cooling water is input, and only a small amount of energy is consumed. This element is therefore performed with a high priority.

Due to the process in step S73, power consumption is reduced and the SOC starts to increase, in a manner as shown at and after time T93. In this case, when the SOC is changed to a state where the SOC is larger than the determination value ε (SOC> determination value ε) (a state when the determination in step S72 is NO), the engine control device performs 2 a fault diagnosis to be performed next, normally, after the currently performed fault diagnosis is completed, ie, performs a diagnosis according to the predetermined order (step S76).

Even in a case where the SOC varies considerably with a detectable variance of the discharge amount of the vehicle by operation on the accelerator pedal while a fault diagnosis is being performed, according to the second embodiment, it is possible to adjust the SOC to be either SOC ≥ determination value α or SOC ≤ determination value γ. Thus, a failure diagnosis can be performed without decreasing a power generation (charge) efficiency, with an accuracy as high as the accuracy obtained by the gasoline-powered vehicle in the prior art.

Various modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope of this invention, and it is understood that this is not limited to the embodiments illustrated herein.

Claims (5)

A series hybrid vehicle comprising: an engine ( 1 ); an energy generator ( 3 ), by the engine ( 1 ) is driven; a battery ( 4 ) generated by the energy generator ( 3 ) is loaded; a drive motor ( 5 ), the wheels ( 6L ) ( 6R ), with energy generated by the energy generator ( 3 ) or energy generated by the battery ( 4 ) is unloaded; and an engine control device ( 2 ), which is the engine ( 1 ), wherein the engine control device ( 2 ) is formed with: a function for detecting a state of charge of the battery ( 4 ); an engine start-up function for starting the engine ( 1 ), when the detected state of charge of the battery ( 4 ) drops to a predetermined value; a fault diagnosis start determining function for starting a power supply for the battery ( 4 ) and the drive motor ( 5 ) by the energy generator ( 3 ), by starting the engine ( 1 ) using the engine start-up function, and determining a start of a fault diagnosis when the state of charge of the battery ( 4 ) rises to a predetermined value; and a function for starting a fault diagnosis when the start of the fault diagnosis is determined by the fault diagnosis start determining function. A series hybrid vehicle according to claim 1, wherein: the engine control device ( 2 ) the fault diagnosis in a range of the state of charge of the battery ( 4 ) of a level γ at which the engine ( 1 ) is in a stop state, up to a level α at which the engine ( 1 ) is in a forced drive state. A series hybrid vehicle according to claim 1, wherein: the engine control device ( 2 ) the fault diagnosis in a range of the state of charge of the battery ( 4 ) of a level γ at which the engine ( 1 ) is in a stop state, up to a level α at which the engine ( 1 ) is in a forced driving state, by determining that a failure diagnosis requiring a large amount of power can be performed with a higher priority when a level of the state of charge of the battery exceeds δ (α <β <δ <γ), and a fault diagnosis that requires only a small amount of power can be performed with a higher priority when the level of the state of charge of the battery ( 4 ) is smaller than ε (α <ε <β <δ), and by determining that the fault diagnoses can be performed according to a predetermined order when the level of the state of charge of the battery ( 4 ) is greater than ε and less than δ. A series hybrid vehicle according to claim 1, wherein: the engine control device ( 2 ) is further configured with a failure diagnosis control function for calculating a required engine power generation amount calculated by a vehicle control device ( 2 ), and one Engine power generation target amount with which an engine drive state required for the failure diagnosis of the vehicle is achieved; and the engine control device ( 2 ) adjusts a power generation amount calculated by the failure diagnosis control function and a power generation amount calculated by the generation amount calculation function to find a target engine speed by calculation, and an engine speed error diagnosis calculated by the engine control apparatus ( 2 ), upon determining the start of the fault diagnosis by the diagnosis start determination function. A series hybrid vehicle according to claim 4, wherein: said engine control device ( 2 ) is further configured with a fault diagnosis element determination function for determining a fault diagnosis element according to a variation of the state of charge of the battery ( 4 ) calculated by the vehicle control device ( 7 ) after the fault diagnosis is started by the fault diagnosis start determination function.

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