JP2006009718A - Engine start timing control method for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce acceleration shock in engine start during EV running. <P>SOLUTION: If a running mode is in the EV running (YES in a step S10), and running information such as actual fuel injection amount Qfin, accelerator opening, and a vehicle speed is read (S20), a virtual engine speed NE0 is calculated (S30), a virtual fuel injection amount Qfin0 is calculated from a governor characteristic map based on the engine speed NE0 and the accelerator opening (S40). A target engine torque TEPn and actual engine torque TETn are calculated by using a torque conversion map, and differential torque ΔTEn is calculated (S50). When an engine start instruction is issued (YES in S60), differential torque ΔTE(n-1) calculated from torque TEP(n-1), TET(n-1) just before the start is held as the differential torque ΔTEn in the start (S70), and the differential torque is set as a torque assist amount Tmg (S80). When the engine start instruction is not issued (NO in S60), the present differential torque ΔTEn is set as the torque assist amount Tmg as it is (S90, S80). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control method for starting an engine of a hybrid vehicle. More specifically, the present invention relates to an engine start of a hybrid vehicle capable of reducing acceleration shock (feeling of idling) when starting the engine when shifting from EV traveling to engine traveling. The present invention relates to a time control method.

  Conventionally, an engine as a travel drive source, a transmission, a clutch for connecting and separating power transmission between the engine and the transmission, and a motor generator for assisting power generation by engine output or engine output by battery power There is known a hybrid vehicle that is configured to be able to travel by either engine traveling using only the engine as a driving source or EV traveling using only the motor generator as a driving source.

  A technology for calculating the torque (output) of a motor generator according to a vehicle target driving torque determined from information on the accelerator opening and the vehicle speed for such a hybrid vehicle, and driving and controlling the motor generator based on the calculated value. Has been proposed (see, for example, Patent Document 1).

  However, in the conventional hybrid vehicle motor torque control method, it is necessary to adapt the acceleration characteristics during EV travel according to the degree of depression of the accelerator pedal, and to have the result as a map with an adaptation constant. In addition, in order to smoothly shift to engine running in response to requests for various running feelings, it is necessary to create a correction map that also conforms to the output characteristics with respect to the accelerator opening.

  For this reason, the motor torque control program requires a large number of man-hours, especially when there are two or more types of maps in the motor generator and engine powertrain systems. It was.

  Accordingly, the applicant of the present application has come to provide a motor torque control method for a hybrid vehicle that can significantly reduce the number of man-hours required (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2000-166022 Japanese Patent Application No. 2004-118120

  However, the technique according to Patent Document 2 has the following problems. That is, when the travel mode of the hybrid vehicle is switched from EV travel to engine travel, a predetermined fuel injection amount required for engine start is instantaneously injected (start-up injection). At this time, the vehicle is in EV travel, and basically the clutch is disengaged, so that the engine driving force is not transmitted to the drive wheels even if the starting boost injection is performed.

  In this way, even if the actual engine torque actually output by the engine is not transmitted to the tire driving force via the transmission, if the start increasing injection is performed, the actual engine torque is as if it is large for a moment. Even if the clutch should be connected while performing torque assist by the motor generator, and the transition should be made smoothly to engine running, the torque assist may be reversed by the erroneous detection. When the amount is reduced and the clutch is connected, there is a risk of accelerating shock (idle feeling).

  The present invention has been made in view of the above, and provides an engine start-time control method for a hybrid vehicle that can reduce acceleration shock at the time of engine start when shifting from EV travel to engine travel. Objective.

  In order to solve the above-described problems and achieve the object, an engine start-time control method for a hybrid vehicle according to claim 1 of the present invention includes an engine as a travel drive source, a transmission, and power generation by the output of the engine. Or a motor generator that assists the engine output by the power of the battery, and can run by either engine running using only the engine as a drive source or EV running using only the motor generator as a drive source. The fuel injection amount is calculated based on the accelerator opening and the engine speed estimated from the travel information during the EV travel, and the virtual engine is calculated based on the fuel injection amount and the estimated engine speed. A torque calculating means for calculating torque, the virtual engine torque, and a real engine actually output by the engine; In an engine start control method for a hybrid vehicle, further comprising an assist amount calculation means for calculating a torque assist amount to be output by the motor generator in accordance with a difference from an engine torque, when the engine is started during the EV traveling The torque assist amount to be output by the motor generator is fixed to a value calculated immediately before starting the engine.

  According to a second aspect of the present invention, there is provided a control method for starting an engine of a hybrid vehicle according to the first aspect of the present invention, wherein the hybrid vehicle is a clutch for connecting and disconnecting power transmission between the engine and the transmission. And clutch engagement degree detection means for detecting the degree of engagement of the clutch, the degree of engagement of the clutch is detected when the engine is running during the EV traveling, and the degree of engagement is a predetermined threshold value. If the degree of engagement is not greater than a predetermined threshold, the torque assist amount to be output by the motor generator is fixed to a value calculated immediately before starting the engine. The torque assist amount to be output by the generator is set to a value calculated when the engine is started.

  According to a third aspect of the present invention, there is provided a control method for starting an engine of a hybrid vehicle according to the first aspect of the present invention, wherein the hybrid vehicle is a clutch for connecting and separating power transmission between the engine and the transmission. And clutch engagement degree detecting means for detecting the degree of engagement of the clutch, and detecting the degree of engagement of the clutch when starting the engine during the EV traveling, and according to the degree of engagement The torque assist amount to be output from the motor generator is adjusted.

  According to a fourth aspect of the present invention, in the engine start control method for a hybrid vehicle according to the fourth aspect of the present invention, the threshold value is determined when the driving force of the engine is actually transmitted to the drive wheels. It is a stroke amount of the clutch.

  According to claim 5 of the present invention, in the engine start control method for a hybrid vehicle according to claim 3, the clutch transmission torque transmitted from the engine to the drive wheels is based on the degree of engagement of the clutch. And the torque assist amount is adjusted according to the clutch transmission torque.

According to the engine start control method for a hybrid vehicle according to the present invention (Claim 1), the torque assist amount to be output by the motor generator at the time of engine start during EV traveling is fixed to a value calculated immediately before engine start. Thus, even in the case of an injection mode that is not converted into driving force to the drive wheels, such as increased injection at the time of engine start, it is erroneously determined that the engine is generating driving force to the driving wheels, and the torque assist amount Can be avoided, and the acceleration shock at the time of starting the engine can be reduced.

  According to the engine start control method for a hybrid vehicle according to the present invention (Claim 2), until it is determined that the driving force of the engine is transmitted to the drive wheels by monitoring the degree of engagement of the clutch. By fixing the torque assist amount to be output by the motor generator to the previous value, it is possible to avoid the torque assist amount from being reduced based on the erroneous determination. Therefore, it is possible to reduce acceleration shock when starting the engine.

  According to the engine start control method for a hybrid vehicle according to the present invention (Claim 3), the torque assist amount of the motor generator is metered according to the degree of engagement of the clutch, thereby finely controlling the torque assist amount. The acceleration shock at the time of starting the engine can be surely reduced.

  According to the engine start control method for a hybrid vehicle according to the present invention (Claim 4), it is easily and reliably determined from the stroke amount of the clutch whether or not the driving force of the engine is actually transmitted to the drive wheels. The torque assist amount by the motor generator can be set appropriately.

  According to the engine start control method for a hybrid vehicle according to the present invention (Claim 5), the clutch transmission torque that changes according to the degree of engagement of the clutch is estimated, and the motor generator is controlled according to the clutch transmission torque. By adjusting the torque assist amount more strictly, the acceleration shock at the time of starting the engine can be further reliably reduced. Therefore, it is possible to make a smooth transition from EV traveling to engine traveling.

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

  First, a schematic configuration of a diesel hybrid vehicle will be described with reference to FIG. Here, FIG. 2 is a schematic diagram showing a schematic configuration of the diesel hybrid vehicle.

  As shown in FIG. 2, a diesel hybrid vehicle (hybrid vehicle) 10 is provided with a diesel engine (hereinafter simply referred to as an engine) 11 as a travel drive source. Although not shown, the engine 11 includes a common rail fuel injection system that controls the fuel injection amount and fuel injection timing, a turbocharger that increases the intake air amount using exhaust gas pressure, and an intake / exhaust valve. And a variable valve timing mechanism for variably controlling the opening / closing operation timing of the valve.

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

Further, the driving force generated by the engine 11 is a stepped transmission (hereinafter referred to as MMT (hereinafter referred to as MMT)) that can perform automatic shifting.
(Multi-mode manual transmission) 12, which is transmitted to the drive wheel 13 via the differential gear 15 and the drive shaft 14.

  The MMT 12 electrically and automatically controls a gear shift operation by an actuator in accordance with a traveling state. Between the engine 11 and the MMT 12, there is provided a clutch 12a that performs contact and separation of power transmission, and the contact and separation operation is electrically and automatically controlled by an actuator according to the running state.

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

  A motor generator (MG) 17 in which a drive system gear unit (gear train) is integrated is connected to a battery 20 that is a chargeable / dischargeable secondary battery via an inverter 19 and functions as a motor that is a travel drive source. The power running mode and the regenerative operation mode functioning as a generator are configured to take two operating states.

  For example, the motor generator 17 receives power supplied from the battery 20 in the power running operation mode, and generates power for driving the drive shaft 14. Thereby, the shift assist can be performed at the time of shifting, and the acceleration assist can be performed at the time of acceleration. In the regenerative operation mode, the motor generator 17 converts the driving force transmitted from the engine 11 or the drive shaft 14 into electric power and charges the battery 20.

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

  The diesel hybrid vehicle 10 configured as described above is based on output information from various sensors such as a vehicle speed sensor and an accelerator opening sensor (not shown) by an electronic control unit (hereinafter referred to as ECU) (not shown) which is a control device. Basic control is performed as follows, and the vehicle can travel in various states.

  The ECU functions as torque calculation means for calculating virtual engine torque, which will be described later, according to the accelerator opening and the vehicle speed, and the motor generator 17 according to the difference between the calculated virtual engine torque and actual engine torque. It also functions as an assist amount calculation means for calculating the torque assist amount by.

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

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

  When the battery charge amount SOC has dropped below a predetermined reference value, the engine 11 is operated at an output that exceeds the required output of the drive shaft 14, and a part of the surplus power is converted into electric power by the motor generator 17. It is regenerated and used for charging the battery 20. When the output torque of the engine 11 is insufficient, the motor generator 17 assists the insufficient torque according to the battery charge amount SOC, and the necessary torque is ensured.

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

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

  Next, an engine start time control method during EV traveling, which is a main part of the present invention, will be described based on FIG. 1 and with reference to FIGS. Here, FIG. 1 is a flowchart showing a control method according to Embodiment 1 of the present invention. FIG. 3 is a map showing the governor characteristics for calculating the fuel injection amount based on the accelerator opening and the engine speed, and is stored in the memory of the ECU. FIG. 4 is a torque conversion map showing the engine torque calculated based on the fuel injection amount and the engine speed, and is stored in the memory of the ECU. The following control is executed by the ECU.

  As shown in FIG. 1, first, it is determined whether or not the diesel hybrid vehicle 10 is traveling on an EV (step S10). In this determination, if the actual rotational speed (actual engine rotational speed) NE of the read engine 11 is, for example, 50 rpm or less, it is determined that EV traveling is in progress. If the vehicle is not in EV travel (No at Step S10), the process returns to the start because it is out of the scope of this control.

  If the vehicle is traveling in EV (Yes at step S10), the actual fuel injection amount Qfin, the accelerator opening, the vehicle speed (travel information), the differential ratio (travel information), the gear ratio (travel information) of the MMT 12, and the shift position (travel information) ) Is read (step S20).

  Based on the read accelerator opening, vehicle speed, differential ratio, MMT12 gear ratio, and shift position, the clutch 12a is connected and the engine is running under those conditions. A virtual engine speed (engine speed estimated from the travel information) NE0 is calculated (step S30).

  Note that in order to connect the clutch 12a, it is necessary that the rotation speed of the engine 11 be equal to or higher than a predetermined minimum value (for example, 1000 rpm), and therefore the calculated virtual engine rotation speed NE0 falls below this minimum value. If so, the minimum value is held as the virtual engine speed NE0.

  Next, based on the virtual engine speed NE0 and the accelerator opening, the virtual fuel injection amount Qfin0 during EV traveling is calculated from the governor characteristic map shown in FIG. 3 (step S40). Note that this governor characteristic map uses an existing engine map for a normal vehicle that uses only the engine as the travel drive source, and adjusts only the governor characteristic (the relationship between the accelerator opening and the fuel injection amount) for hybrid vehicles. It is a diversion.

  Next, a target engine torque (virtual engine torque) TEPn is calculated from the virtual fuel injection amount Qfin0 and the virtual engine speed NE0 using the torque conversion map shown in FIG. 4, and the actual fuel read in step S20 is calculated. An actual engine torque TETn is calculated from the injection amount Qfin and the actual engine speed NE used in the determination in step S10 (step S50).

  Then, a differential torque ΔTEn between these target engine torque TEPn and actual engine torque TETn is calculated (step S50). The subscript n in the target engine torque TEPn, the actual engine torque TETn, and the differential torque ΔTEn is an arbitrary integer indicating the number of executions of this control program executed at a predetermined timing, and the current number of executions is n. Then, the previous execution count is (n−1).

Next, it is determined whether or not the starter of the engine 11 is ON, that is, whether or not a start command for the engine 11 is issued, and an injection command for a predetermined fuel injection amount is issued at the time of start (step S60). . If the starter is ON (Yes at step S60), the engine 11 has shifted to the start control mode, so that a predetermined fuel injection amount Qst (for example, 15 to 20 mm ³ / st) required for start is instantaneously Injection (start-up amount injection) is performed.

  However, since the vehicle is currently traveling in EV and the clutch 12a is basically disengaged, the driving force of the engine 11 is not transmitted to the MMT 12 even if the fuel injection amount Qst is injected for a moment, and therefore, the differential gear 15 and the drive It is not transmitted to the drive wheel 13 via the shaft 14.

  Even when the actual engine torque TET is not generated as described above, when the fuel injection amount Qst is injected for a moment, the actual engine torque TET seems to have a large value (for example, 60 to 80 Nm) for a moment. Even if the clutch 12a should be connected while performing torque assist by the motor generator 17, and the transition to engine running should be smoothly performed, the torque assist amount is reduced by the erroneous detection. If the clutch 12a is connected, an acceleration shock may occur.

  Therefore, the target engine torque TEP (n−1) and the actual engine torque immediately before the start command of the engine 11 is issued so that the torque assist amount is not reduced even if the fuel injection amount Qst is instantaneously injected. The differential torque ΔTE (n−1) calculated from TET (n−1) is held (fixed) as the differential torque ΔTEn at the time of starting the engine 11 (step S70). Then, the held differential torque ΔTEn is set as a torque assist amount Tmg to be output by motor generator 17 (step S80).

  On the other hand, if the starter is not turned on in step S60 (No in step S60), the engine 11 has not shifted to the start control mode and the start-up injection is not performed, so that the acceleration shock may occur. Nor. Therefore, the differential torque ΔTEn calculated in step S50 is set as the current differential torque ΔTEn (step S90), and the differential torque ΔTEn is set as the torque assist amount Tmg to be output by the motor generator 17 (step S80).

  By controlling as described above, the engine 11 is driven even in the case of an injection mode that is not converted into driving force to the drive wheels 13 such as start-up injection (start-up injection) of the engine 11 during EV traveling. It is possible to avoid erroneous determination that the driving force to the wheel 13 is generated, and to reduce the acceleration shock when starting the engine 11 during EV traveling.

  In the first embodiment, the present invention is applied to the hybrid vehicle 10 that uses the diesel engine 11 as a travel drive source. However, the present invention is not limited to this and is applied to a hybrid vehicle that uses a gasoline engine as a travel drive source. May be.

  Although the present invention is applied to the diesel hybrid vehicle 10 provided with the MMT 12, the present invention is not limited to this, and an automatic transmission (AT), a manual transmission (MT), and a continuously variable transmission (CVT) are provided. The present invention may be applied to other hybrid vehicles.

  FIG. 5 is a flowchart showing a control method according to Embodiment 2 of the present invention. In the following description, the same members or step numbers as those already described are denoted by the same reference numerals and redundant description will be omitted, and only different points will be described.

  In addition to the configuration shown in the first embodiment, the configuration of the diesel hybrid vehicle 10 in the second embodiment further detects a clutch stroke Cst (stroke amount) as an engagement degree that is an index of the contact / separation state of the clutch 12a. A clutch stroke sensor (clutch engagement degree detection means) (not shown) is provided. This is because it is possible to easily and surely determine whether or not the driving force of the engine 11 is actually transmitted to the driving wheels 13 by monitoring the stroke amount of the clutch 12a.

  Therefore, in the control method according to the second embodiment, the driving force of the engine 11 is actually applied to the drive wheels 13 by detecting the clutch stroke Cst of the clutch 12a when the start-up injection of the engine 11 during EV traveling is performed. It is determined whether or not the torque is being transmitted, and the torque assist amount by the motor generator 17 is set according to the determination result. Hereinafter, a description will be given based on FIG. 5 with reference to FIG.

  As shown in FIG. 5, step S10 to step S60 and step S70 to step S90 are the same as those in the first embodiment (see FIG. 1), so the same step numbers are assigned and duplicate explanation is omitted. . The difference from the first embodiment is that step S62, step S64, and step S66 are added.

  That is, when the starter is turned on and the engine 11 is shifted to the start control mode (Yes at step S60), the clutch 12a is connected (engaged) to transmit the driving force of the engine 11 to the MMT 12, and the clutch Since the clutch stroke Cst of 12a gradually changes (becomes smaller) toward the connection side, the clutch stroke Cst is detected and read by the clutch stroke sensor (step S62).

  The clutch stroke Cst of the clutch 12a is a stroke value determined to cause the driving wheel 13 to generate a predetermined driving force (the stroke value including the slip state when the clutch 12a is connected and is hereinafter referred to as a driving force). It is determined whether it is larger than the occurrence determination stroke value (step S64). The driving force generation determination stroke value is an optimum value obtained in advance by experiments or the like so that torque shock is minimized, and is stored in the ECU as a map.

If the clutch stroke Cst is larger than the driving force generation determination stroke value (Yes at step S64), it can be determined that the clutch 12a is not in the connected state necessary for generating the driving force, and therefore, the start increasing injection is performed. The differential torque ΔTE calculated from the target engine torque TEP (n−1) and the actual engine torque TET (n−1) immediately before the start command of the engine 11 is issued so that the torque assist amount is not reduced. (n−1) is held as the differential torque ΔTEn at the time of starting the engine 11 (step S70). Then, the held differential torque ΔTEn is set as a torque assist amount Tmg to be output by motor generator 17 (step S80).

  On the other hand, if the clutch stroke Cst is not larger than the driving force generation determination stroke value (No in step S64), the clutch 12a is in a connected state necessary for generating the driving force, and a predetermined actual value is generated during the start-up increase injection. It can be determined that the engine torque TET is generated.

  Therefore, the differential torque ΔTEn calculated in step S50 is set as the current differential torque ΔTEn (step S66), and the differential torque ΔTEn is set as the torque assist amount Tmg to be output by the motor generator 17 (step S80).

  As described above, the driving force of the engine 11 is actually transmitted to the drive wheels 13 by monitoring the stroke amount of the clutch 12a even in the case of the start-up injection (start-up increase injection) of the engine 11 during EV traveling. Until it is determined that the torque assist amount Tmg has been set, the torque assist amount Tmg to be output by the motor generator 17 is fixed to the immediately preceding value to avoid the torque assist amount Tmg being reduced based on the erroneous determination. be able to. Therefore, the acceleration shock when starting the engine 11 can be reduced.

  FIG. 6 is a flowchart showing a control method according to Embodiment 3 of the present invention. The configuration of the diesel hybrid vehicle 10 in the third embodiment is the same as the configuration shown in the second embodiment.

  The control method according to the third embodiment detects the clutch stroke Cst of the clutch 12a when the start-up injection of the engine 11 during EV traveling is performed, and transmits the detected clutch stroke Cst from the engine 11 to the drive wheels 13 via the clutch 12a. The torque (hereinafter referred to as clutch transmission torque TEcst) is estimated, and the torque assist amount to be output by the motor generator 17 is adjusted according to the clutch transmission torque TEcst. Hereinafter, a description will be given based on FIG. 6 with reference to FIG.

  As shown in FIG. 6, steps S10 to S60, step S80, and step S90 are the same as those in the case of the first embodiment (see FIG. 1). . The difference from the first embodiment is that step S62, step S67, and step S68 are added. Further, since step S62 is the same as that in the second embodiment (see FIG. 5), the same step number is assigned and a duplicate description is omitted.

  That is, when the clutch stroke Cst of the clutch 12a is read (step S62), the clutch transmission is performed based on a predetermined calculation formula or a predetermined map from the clutch stroke Cst and the actual engine torque TETn calculated in step S50. Torque TEcst is calculated (step S67).

  In this way, the clutch transmission torque TEcst that changes according to the clutch stroke Cst can be calculated more strictly. A known theoretical formula can be used as the predetermined calculation formula. Moreover, the value calculated based on the said well-known theoretical formula can be used for this predetermined map.

Next, a differential torque ΔTEn is calculated from the target engine torque TEPn calculated in step S50 and the clutch transmission torque TEcst calculated in step S67 (step S68). As described above, in the third embodiment, the differential torque ΔTEn that changes according to the clutch stroke Cst can be calculated more strictly than in the second embodiment. Therefore, if this differential torque ΔTEn is set as torque assist amount Tmg to be output by motor generator 17 (step S80), the torque assist amount can be set more strictly.

  As described above, even in the case of the start-up injection (start-up increase injection) of the engine 11 during EV traveling, the clutch transmission torque TEcst that changes according to the stroke amount of the clutch 12a is estimated, and this clutch transmission torque TEcst is estimated. Accordingly, by adjusting the torque assist amount Tmg of the motor generator 17, the acceleration shock at the start of the engine 11 can be surely reduced, and the transition from EV traveling to engine traveling can be performed more smoothly.

  As described above, the engine start control method for a hybrid vehicle according to the present invention is useful as a control method for shifting the hybrid vehicle from EV travel to engine travel, and particularly reduces acceleration shock at engine start. Suitable for control method aiming at.

It is a flowchart which shows the control method which concerns on Example 1 of this invention. It is a mimetic diagram showing a schematic structure of a diesel hybrid vehicle. It is a map which shows the governor characteristic for calculating fuel injection quantity based on an accelerator opening and an engine speed. It is a torque conversion map which shows the engine torque calculated based on fuel injection quantity and an engine speed. It is a flowchart which shows the control method which concerns on Example 2 of this invention. It is a flowchart which shows the control method which concerns on Example 3 of this invention.

Explanation of symbols

10 Diesel hybrid vehicle (hybrid vehicle)
11 Diesel engine (engine)
12 MMT (transmission)
12a Clutch 13 Drive wheel 17 Motor generator 20 Battery Cst Clutch stroke NE Actual engine speed NE0 Virtual engine speed (engine speed estimated from travel information)
Qfin Actual fuel injection amount Qfin0 Virtual fuel injection amount TETn Current actual engine torque TEPn Current target engine torque (virtual engine torque)
TET (n-1) Actual engine torque just before engine start TEP (n-1) Target engine torque (virtual engine torque) just before engine start
TEcst Clutch transmission torque ΔTEn Current differential torque ΔTE (n−1) Differential torque immediately before engine start Tmg Torque to be output by motor generator

Claims (5)

An engine running using only the engine as a drive source and the motor generator, comprising: an engine as a running drive source; a transmission; and a motor generator for generating power by the engine output or assisting the engine output by battery power. It is configured to be able to travel by any one of EV traveling using only the driving source,
During the EV travel, the fuel injection amount is calculated based on the accelerator opening and the engine speed estimated from the travel information, and the virtual engine torque is calculated based on the fuel injection amount and the estimated engine speed. Torque calculating means for
When the engine of the hybrid vehicle further includes an assist amount calculation means for calculating a torque assist amount to be output by the motor generator according to a difference between the virtual engine torque and an actual engine torque actually output by the engine. In the control method,
A control method for starting an engine of a hybrid vehicle, wherein a torque assist amount to be output by the motor generator when starting the engine during the EV traveling is fixed to a value calculated immediately before starting the engine. The hybrid vehicle further includes a clutch that performs power transmission / reception between the engine and the transmission, and a clutch engagement degree detection unit that detects an engagement degree of the clutch,
Detecting the degree of engagement of the clutch at the start of the engine during the EV running;
If the degree of engagement is greater than a predetermined threshold, the torque assist amount to be output by the motor generator is fixed to a value calculated immediately before starting the engine,
2. The hybrid according to claim 1, wherein when the degree of engagement is not greater than a predetermined threshold, the torque assist amount to be output by the motor generator is set to a value calculated at the time of starting the engine. A control method for starting an engine of a vehicle. The hybrid vehicle further includes a clutch that performs power transmission / reception between the engine and the transmission, and a clutch engagement degree detection unit that detects an engagement degree of the clutch,
The degree of engagement of the clutch is detected when starting the engine during the EV traveling, and a torque assist amount to be output by the motor generator is adjusted according to the degree of engagement. The engine start control method of the described hybrid vehicle.   The method of claim 2, wherein the threshold value is a stroke amount of the clutch when the driving force of the engine is actually transmitted to driving wheels.   The clutch assist torque transmitted from the engine to the driving wheel is estimated based on the degree of engagement of the clutch, and the torque assist amount is adjusted according to the clutch transmit torque. The engine start control method of the described hybrid vehicle.

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