JP2002115586A - Engine start control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine start control device capable of favorably suppressing the abrupt increase in the rotation speed in firing of an engine even in cold start. SOLUTION: A crankshaft 16 of the engine 2 is connected to a pulley 20 via an electromagnetic clutch 18. In restarting control of the engine 2 after controlling its automatic stop, a driving force of a motor generator 30 is transmitted to the pulley 20 via a pulley 26 and a belt 22 and finally applied to the crankshaft 16 of the engine 22. When the rotating speed applied to the crankshaft 16 reaches a prescribed value, the firing of the engine 2 is preformed. In starting the firing 16, the opening of a throttle valve 2c is set to such an opening as retained by the drive of the engine 2. In the cold start, the opening of the throttle valve 2c is gradually increased so as to reach a rotation speed according to the cold idling rotation speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine start control device, and more particularly to an engine start control device suitable for use in a vehicle in which the engine is started in a state where the driving force of the engine can be transmitted to driving wheels. About.

[0002]

2. Description of the Related Art Conventionally, an engine for automatically stopping an engine when a vehicle is stopped, for example, when waiting for a traffic light, and restarting the engine when the vehicle starts moving, for the purpose of improving fuel efficiency when driving in an urban area with a high stopping rate. Automatic stop and start devices are known.

[0003] The automatic stop / start device is often mounted on a vehicle equipped with an automatic transmission. In this case, in order to smoothly start the vehicle, even when the engine is automatically stopped, the automatic stop / start device is used. It has been proposed to maintain the transmission in the engaged state of the gear corresponding to the starting shift position.

However, in a vehicle equipped with such an automatic stop / start device for an engine, when the driver depresses the accelerator pedal excessively at the time of starting, the following inconvenience occurs. May occur. That is, since the intake air amount of the engine rises at a stretch with excessive depression of the accelerator pedal, the engine rotation speed also rises rapidly. Then, since the engine torque that rapidly increases with the rapid increase in the engine rotation speed is transmitted to the drive wheels, the uncomfortable feeling given to the occupant cannot be ignored.

Therefore, conventionally, for example, Japanese Unexamined Patent Application Publication No.
As can be seen in Japanese Patent Publication No. 139, at the time of automatic engine start, the throttle opening is fixed to a value optimum for starting regardless of the operation amount of the accelerator pedal, and after the start, the fixed throttle opening is used as the accelerator pedal operation amount. A technique for gradually increasing the opening to a corresponding degree has also been proposed.

[0006]

When the engine is started in a cold state, the first idling speed in a cold state set higher than the first idling speed in the warmed state is set because the engine is warmed up early. It is common practice to control the engine rotation speed by speed. At the time of the cold start, the throttle opening corresponding to the first idle rotation speed at the time of the cold becomes the optimum throttle opening for the above-described start. However, in the above-described conventional start control device, if the throttle opening is fixedly controlled to a throttle opening corresponding to the first idle rotation speed in the cold state during the cold automatic start, the rotation speed of the engine rapidly increases after the firing. However, the discomfort given to the occupants cannot be ignored.

On the other hand, there are known vehicles that run with the driving force of a motor at the time of start and also motorize the engine. Even in such a vehicle, a required idle rotation speed as in a cold state is required. If the required amount of air is higher than that after complete warm-up, the rotation speed of the engine similarly increases rapidly after firing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an engine capable of suitably suppressing a rapid increase in rotation speed due to firing of the engine even during a cold start. It is to provide a starting control device.

[0009]

The means for achieving the above object and the effects thereof will be described below. According to a first aspect of the present invention, there is provided an engine start control device in which engine start control is performed in a state where the driving force of the engine can be transmitted to driving wheels of a vehicle. Setting means for setting the degree of adjustment of the amount of intake air so that the speed is higher than the first idle speed at the time of warming up of the engine; and at the time of cold start of the engine, with the start of firing The gist of the invention is to provide gradual change means for gradually increasing the adjustment degree of the intake air amount to the adjustment degree corresponding to the first idle rotation speed at the time of the cold start.

In the above configuration, when the engine is cold started,
There is provided a gradual change means for gradually increasing the adjustment degree of the intake air amount with the start of the firing to the adjustment degree corresponding to the first idle rotation speed at the time of the cold start. Therefore, according to the above configuration, even in a cold state, even if the degree of adjustment of the intake air amount set by the setting unit is large, the above-described problem such as a rapid increase in the rotation speed of the engine during firing is avoided. Can be avoided.

According to a second aspect of the present invention, there is provided an engine and an electric motor connected to an output shaft thereof, and the driving force to the drive wheels is sequentially switched from the driving force by the electric motor to the driving force by the engine when starting. In an engine start control device employed in a vehicle, the amount of intake air is adjusted so that a fast idle speed at the time of cold start of the engine is higher than a fast idle speed at the time of warming of the engine. Setting means for setting the degree, at the time of the cold start of the engine, at the time of the cold start, the degree of adjustment of the intake air amount along with the start of firing from the degree of adjustment corresponding to a predetermined initial rotation speed. And a gradual change means for gradually increasing the adjustment amount to the degree of adjustment corresponding to the first idle rotation speed.

In the above configuration, when the vehicle starts, the driving force to the driving wheels is sequentially switched from the driving force by the electric motor to the driving force by the engine. If it is large, a large torque step may be generated between the torque generated by the electric motor and the torque generated by the engine when firing is started. On the other hand, in order to increase the rotation speed generated by the electric motor in order to reduce the torque step, it is necessary to increase the size of the electric motor and the battery, and the power consumption is increased. In this regard, according to the above configuration, when switching the transmission mode of the driving force described above, the degree of adjustment of the intake air amount is changed from a value corresponding to the initial rotation speed to a value corresponding to the first idle rotation speed during cold start. By gradually increasing the number, these problems can be avoided.

According to a third aspect of the present invention, in the second aspect, the initial rotational speed is a rotational speed applied to an output shaft of the engine by the electric motor.

According to the above configuration, by setting the initial rotational speed to the rotational speed applied to the output shaft of the engine by the electric motor, it is possible to preferably avoid a torque step due to firing. .

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the adjustment degree of the set intake air amount is added to the load in accordance with the operation of the engine accessory. Correction means for increasing the amount of the intake air, and the gradual change means, when gradually changing the adjustment degree of the intake air amount, sets the gradual change final value to the increased value. I do.

According to the above configuration, an air conditioner, a light, etc.
During operation of the engine accessories, the operation of the accessories can be suitably dealt with by gradually changing the degree of adjustment of the intake air amount by the gradual change means to a value increased and corrected according to the load. become able to.

Even if the same gradual change operation is performed, the gradual change amount may be changed according to the magnitude of the electric load in consideration of the fact that the manner of increase in the engine rotational speed changes depending on the magnitude of the electric load.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the gradual change means changes the gradual change speed in accordance with an operation amount of an accelerator operation means. And

According to the above configuration, since the gradual change amount is changed in accordance with the operation amount of the accelerator operation means, when the driver has a will to accelerate, the gradual change amount is increased to increase the driver's will. It can be reflected.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine start control device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram schematically showing the configuration of the present embodiment. In the present embodiment, the output of the engine 2 shown in FIG. 1 is subjected to a predetermined change by the torque converter 4 and the gear transmission unit 6, and then output shaft 8
Output from The gear transmission unit 6 includes a plurality of planetary gear mechanisms, and is a portion that changes the input driving force in five forward steps and one reverse step, and maintains the engaged state of the gears of these planetary gear mechanisms. The switching of the engagement is performed by the hydraulic control unit 10.

That is, the hydraulic control unit 10 controls the engine 2
At the time of the operation, the engagement control and the switching control of the gears of the planetary gear mechanism are performed using the hydraulic oil pressurized by the oil pump 12. The oil pump 12 is driven by the power of the engine 2 and is provided between the torque converter 4 and the gear transmission 6 as shown in FIG.

On the other hand, when the engine 2 is automatically stopped, the hydraulic control unit 10 uses the hydraulic oil pressurized by the electric oil pump 14 provided near the torque converter 4 to stop the engine 2 when the engine 2 is stopped. Also, the engagement of the gears of the planetary gear mechanism in the gear transmission unit 6 is controlled so as to correspond to the starting shift position.

More specifically, the control of the gear transmission unit 6 by the hydraulic control unit 10 is performed by controlling the clutches C0 to C2 and the brake B of the gear transmission unit 6 shown in the skeleton diagram of FIG.
0 to B4, and among the one-way clutches F0 to F2, the engagement modes of the hydraulically driven clutches C0 to C2 and the brakes B0 to B4 are controlled by hydraulic oil. Thus, the clutches C0 to C2 and the brakes B0 to B0
By controlling the engagement mode of B4 with hydraulic oil, FIG.
The engagement control of the gears according to the respective gears shown in FIG. In particular, during the automatic stop control of the engine 2 described above, the engagement state of the first speed gear shown in FIG. 3 is maintained corresponding to the starting shift position. If the hydraulic pressure of the hydraulic oil is not sufficient at the time of the automatic stop control of the engine 2, the clutch C1 may slip when starting, and therefore the engagement control of the clutch C1 is performed using the hydraulic oil pressurized by the electric oil pump 14. You. Thereby, when starting, the clutch C1
A smooth start is possible without slipping.

The output of the engine 2 shown in FIG. 1 is output from the electromagnetic clutch 1 connected to the crankshaft 16.
8, and further transmitted to the belt 22 via the pulley 20. Further, a rotational force is applied to the pulleys 24 and 26 by the driving force transmitted to the belt 22. The electromagnetic clutch 18 switches between transmission and non-transmission of the driving force between the crankshaft 16 and the pulley 20.

On the other hand, the rotational force of the pulley 24 is controlled by an air conditioner compressor 28 used to operate the air conditioner.
Supplied to On the other hand, the rotational force of the pulley 26 is supplied to the motor generator 30. In the motor generator 30, power is generated by the rotational force supplied from the pulley 26, and the generated power is
Is supplied to the battery 34 via the. The motor generator 30 also has a function as a motor. In this case, the amount of power supplied from battery 34 is adjusted by inverter 32, so that the rotation speed of motor generator 30 is variably controlled.

The engine 2, the hydraulic control unit 10, the electric oil pump 14, the electromagnetic clutch 18, the motor generator 30, the inverter 32, and the electronically controlled throttle valve 2 c provided in the intake passage of the engine 2. The control is performed by an electronic control unit (hereinafter, referred to as ECU) 40. The ECU 40 includes an ignition switch 41, a vehicle speed sensor 42 for detecting a vehicle speed, and an accelerator sensor 4 for detecting an amount of depression of an accelerator pedal.
3. A brake sensor 44 for detecting whether a brake for keeping the vehicle in a stopped state is depressed, a rotation speed sensor 45 for detecting an output rotation speed of the engine 2, a water temperature sensor 46 for detecting a cooling water temperature of the engine 2, and the like. , The amount of power generated by the motor generator 30, the battery voltage, and the like.

Next, the automatic stop control of the engine 2 in this embodiment will be described. In this embodiment,
(A) The ignition switch 41 is turned on (b) The vehicle speed sensor 42 detects that the vehicle speed is "0" (c) The accelerator sensor 43 detects that the accelerator pedal is not depressed (D) The automatic stop control of the engine 2 is performed when all the conditions such as that the brake sensor 44 confirms that the brake is depressed are satisfied for a predetermined time or more.

When the automatic stop control of the engine 2 is performed,
Fuel injection from an injector provided in the engine 2 is stopped, and ignition control by a spark plug provided in the engine 2 is also stopped. As a result, the engine 2 is stopped. Further, with the stop control of the engine 2, the drive of the electric oil pump 14 is controlled, and the hydraulic oil of the hydraulic control unit 10 is pressurized by the electric oil pump 14. Using the pressurized hydraulic oil, the hydraulic control unit 10 controls the engagement of the gears of the gear transmission unit 6 to a state corresponding to the starting shift.

Next, the automatic start control according to the present embodiment will be described. In this embodiment, (b) the vehicle speed sensor 42 detects that the vehicle speed is "0". (C) The accelerator sensor 43 detects that the accelerator pedal is not depressed. (D) Brake The automatic start control of the engine 2 is performed on condition that even one of the conditions such as the fact that the brake is depressed by the sensor 44 is not satisfied.

In the automatic start control of the engine 2, a driving force is applied to the crankshaft 16 by using the motor generator 30 described above as a motor. The driving force applied to the crankshaft 16 is transmitted to the engine 2 and the torque converter 4. As described above, at the time of the automatic start control of the engine 2 of the present embodiment, the driving force is applied to the engine 2 by the motor generator 30 without using the starter (not shown).

When the condition such as the rotation speed of the crankshaft 16 by the motor generator 30 reaches a predetermined value is satisfied, the engine 2 fires. That is, the fuel injection control and the ignition timing control of the engine 2 are started. As described above, in the present embodiment, when the engine 2 is automatically started, the torque converter 4
The driving force transmitted to the motor is first supplied by the motor generator 30, and then the switching control is performed so as to be supplied by the engine 2.

However, when the motor 2 is switched from the motor generator 30 to the engine 2, if the idle speed of the engine 2 is set to the normal value, the target idle speed is high in the cold state. As described above, the torque output from the motor 8 changes greatly, and the discomfort given to the occupant cannot be ignored.

Therefore, in the present embodiment, at the time of the switching, the intake air amount according to the rotation speed of the engine 2 applied to the crankshaft 16 by the motor generator 30 is set as the target intake air amount. And then
Control is performed such that the target intake air amount is gradually increased to an intake air amount corresponding to the idle rotation speed at the time of cold.

Specifically, at the time of the above switching, the throttle valve 2 shown above corresponds to the rotation speed given to the output shaft of the engine 2 by the motor generator 30.
Set the opening of c. Thereafter, the throttle opening is gradually increased to a throttle opening corresponding to the target idle rotation speed in the cold state.

FIG. 4 shows the throttle valve 2c
4 shows changes in the idle rotation speed and the opening of the throttle valve 2c in the cold state in the present embodiment in which the opening of the throttle valve 2 is gradually changed.

As shown in FIG. 4, at time t1, when the automatic start control of the engine 2 is started, first,
By operating the motor generator 30, the rotation speed of the output shaft of the engine 2 increases to a predetermined rotation speed (motoring rotation speed). In addition to the operation control of the motor generator 30, the throttle valve 2c
Is controlled to an opening necessary to maintain the motoring rotational speed only by driving the engine 2.

At time t2, when it is confirmed that the rotation speed of the output shaft of the engine 2 by the motor generator 30 has increased to a predetermined rotation speed (motoring rotation speed), for example, the motor 2 The earring is started, and the opening of the throttle valve 2c is also gradually controlled to increase. As a result, the rotation speed of the engine 2 starts increasing from the motoring rotation speed at a time t3 slightly later than the time t2, and approaches the idle rotation speed in a cold state.

As described above, at the time of cold start, when the control for switching the supply source of the driving force from the motor generator 30 to the engine 2 is performed, the rotation speed of the engine 2 is gradually increased to the idle rotation speed at the time of cold. By doing so, the torque output from the engine 2 to the torque converter 4 shown in FIG. Therefore, it is possible to avoid a rapid increase in the rotation speed of the engine 2 due to the start of the vehicle.

Here, a start control procedure of the engine 2 according to the present embodiment will be described with reference to FIGS.
FIG. 5 is a routine showing a procedure for controlling the operation of the motor generator 30 which is performed first when the automatic start control of the engine 2 in the present embodiment is started. This routine
It is started by interruption every predetermined period.

That is, in this routine, first, in step 100, it is determined whether or not the automatic start condition of the engine 2 is satisfied. If it is determined that this condition is not satisfied, this routine is temporarily terminated.

On the other hand, if it is determined in step 100 that the condition for automatically starting the engine 2 is satisfied, it is determined whether the rotation speed of the output shaft of the engine 2 is equal to or higher than the motoring rotation speed. . Then, if it is determined that the motoring rotation speed has not been reached, step 12
At 0, the motoring travel flag is turned on, and the operation of the motor generator 30 is controlled. Further, in this case, in step 130, the motoring travel storage flag is turned on, and this routine is temporarily ended.

On the other hand, if it is determined in step 110 that the rotation speed of the output shaft of the engine 2 is equal to or higher than the above-mentioned motoring rotation speed, the motoring travel flag is turned off in step 140 and the motor generator 30 The power supply to is stopped, and this routine ends.

The motoring travel storage flag is turned off, for example, when the automatic stop control of the engine 2 is performed. FIG. 6 shows the engine 2 according to the present embodiment.
Is a routine showing a procedure of automatic start control of the first embodiment. This routine is also started by interruption every predetermined period.

In this routine, first, step 2
At 00, it is determined whether the motoring travel storage flag is on and the motoring travel flag is off. That is, here, it is determined whether or not the rotation speed of the output shaft of the engine 2 has reached the motoring rotation speed by the operation of the motor generator 30. Then, if it is determined that this condition is not satisfied, this routine is temporarily ended.

On the other hand, if it is determined in step 200 that the rotation speed of the output shaft of the engine 2 has reached the above-mentioned motoring rotation speed by the motor generator 30, in step 210, the target air amount sucked into the engine 2 is determined. It is determined whether or not the variable x temporarily stored in the calculation of is smaller than the target air amount calculation value. Here, when the condition of step 200 is satisfied for the first time, the variable x is set as an initial value to the amount of air necessary to obtain the motoring rotational speed only by driving the engine 2. The target air amount calculation value referred to here is a target air amount calculated according to the operating state. At the time of starting, the cold start is performed based on the detection result of the water temperature sensor 46 shown in FIG. Is determined, the target air amount is calculated as the target air amount corresponding to the idle target rotation speed in the cold state that is higher than the idle target rotation speed in the warm air state. Further, when the auxiliary equipment of the engine 2 such as the air-conditioner compressor 28 is operated, the target air amount is calculated as the target air amount according to the idle rotation speed in consideration of the operation of the auxiliary equipment.

If it is determined in step 210 that the variable x is smaller than the calculated target air amount, step 2 is executed.
At 20, it is determined whether or not the accelerator pedal is depressed based on the detection result of the accelerator sensor 43 shown in FIG. 1 (accelerator opening “0” determination flag is on). This determination is for confirming the intention of the driver to accelerate.

If it is determined in step 220 that the accelerator pedal has not been depressed, the variable x
Is increased by a first gradual variable. On the other hand, step 22
At 0, when it is determined that the accelerator pedal is depressed, the variable x is increased by a second gradual change larger than the first gradual change.

Then, step 230 and step 24
When the variable x is increased by a predetermined amount at 0, the process proceeds to step 250. Also in this step 250,
It is determined whether the variable x is less than the target air amount calculation value.
If it is determined that the variable x is smaller than the target air amount calculation value, the routine proceeds to step 260, where the target air amount command value is set to this variable x, and this routine is once ended.

Also, in step 210 or step 2
If it is determined in step 50 that the variable x is equal to or larger than the target air amount calculation value, in step 270, the variable x is set as the target air amount calculation value, and the routine proceeds to step 260.

Then, based on the calculated target air amount set in step 260, the throttle valve 2c
Is controlled. Note that this routine is performed once in step 2
When the process of step 70 is performed, the engine 2 does not start until the next automatic start.

According to the embodiment described above, the following effects can be obtained. (1) When firing the engine 2, the opening of the throttle valve 2c is set in accordance with the motoring rotation speed, and then, in a cold state, the opening degree is adjusted to the first idle rotation speed in the cold state. By gradually increasing the rotation speed, it is possible to avoid a problem such as a sudden increase in the rotation speed caused by the firing of the engine 2.

(2) The gradual change in increasing the opening of the throttle valve 2c to an opening corresponding to the idling rotational speed in a cold state is changed depending on whether or not the accelerator pedal is depressed. Thus, the driver's intention to accelerate can be accurately reflected.

The above embodiment may be modified and implemented as follows. The conditions for performing the automatic stop control and the automatic start control of the engine 2 described in the above embodiment may be appropriately changed and performed.

In the above embodiment, the intake air amount at the start of the firing of the engine 2 is set to the intake air amount at which the rotation speed at the time of motoring can be maintained only by driving the engine 2. Is not necessarily performed, and can be set arbitrarily. However, from the viewpoint of the torque step due to the switching, it is desirable that the intake air amount at the start of firing of the engine 2 be set to approximate the intake air amount according to the rotation speed at the time of motoring.

In the above embodiment, as shown in FIG. 6, the gradual change process is performed by controlling the throttle valve 2c. However, the present invention is not limited to this. Any means that can be controlled may be used.

Further, in this embodiment, at the time of automatic engine start, the driving force of the motor generator 30 is supplied to the torque converter 4 and the engine 2 is fired after reaching the motoring rotation speed. However, the engine 2 may be automatically started using a starter without using the motor generator 30. In this case, the rotation speed of the engine 2 at the start of firing may be set to a value that can suitably suppress the shock accompanying the start of firing. Alternatively, the rotational speed may not be set, but may be set to an intake air amount that can appropriately suppress a shock. With such a configuration, even when engagement of the gear corresponding to the starting shift position is maintained,
Shock accompanying firing can be suppressed.

The automatic transmission is not limited to an automatic transmission as long as the gear engagement mode is maintained at the starting shift position at the start of firing upon starting of the engine. Further, at the time of starting firing when the engine is started, the engagement of the gears does not necessarily have to be maintained in the starting shift, and any configuration may be used as long as the driving force of the engine can be transmitted to the drive transmission system. .

In the above embodiment, the amount of gradual change is changed depending on whether or not the accelerator pedal is depressed. However, the present invention is not limited to the accelerator pedal, and operation of any accelerator operating means for confirming the driver's intention to accelerate. The gradual change speed may be changed based on the amount.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an engine start control device according to the present invention.

FIG. 2 is a skeleton diagram in the gear transmission unit of the embodiment.

FIG. 3 is an explanatory view of the operation engagement of gears in the gear transmission of the embodiment.

FIG. 4 is a time chart showing changes in the rotation speed and the amount of air accompanying firing of the engine of the embodiment.

FIG. 5 is a flowchart showing a control procedure of the motor generator accompanying the engine start control of the embodiment.

FIG. 6 is a flowchart showing an engine start control procedure of the embodiment.

[Explanation of symbols]

2 ... Engine, 2c ... Throttle valve, 4 ... Torque converter, 6 ... Gear transmission unit, 8 ... Output shaft, 10 ... Hydraulic control unit, 12 ... Oil pump, 14 ... Electric oil pump, 16 ... Crank shaft, 18 ... Electromagnetic clutch, 20, 24, 26 ... pulley, 22 ... belt, 28 ...
Air conditioner compressor, 30 ... motor generator,
32 inverter, 34 battery, 40 electronic control device, 41 ignition switch, 42 vehicle speed sensor, 43 accelerator sensor, 44 brake sensor, 4
5: rotational speed sensor, 46: water temperature sensor, 2c: throttle valve.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI theme coat ゛ (reference) F02N 15/00 F02N 15/00 EF term (reference) 3G092 AA01 AC03 BA01 BA03 BA10 BB10 CA01 CB04 DC03 EA01 EA11 EA17 EA22 FA05 GA01 GA02 GB01 HA01X HA06X HE01Z HE08Z HF01Z HF02Z HF03Z HF05X HF08Z HF19Z HF21Z HF26Z 3G093 AA05 BA02 BA21 CA01 CA03 CB05 DA01 DA05 DA06 DA09 DA12 DB05 DB10 DB11 DB25 DB26 EA03 EA03 FB03 DB01 MA24 NE03 NE23 PA01Z PA11Z PB03Z PE01Z PE08Z PE09Z PF01Z PF03Z PF05Z PF08Z PF12Z PF13Z PF16Z

Claims (5)

[Claims] 1. An engine start control apparatus for controlling start of an engine in a state where the driving force of the engine can be transmitted to driving wheels of a vehicle, wherein the first idle rotation speed at the time of cold start of the engine is the same. Setting means for setting the degree of adjustment of the intake air amount such that the rotation speed becomes higher than the first idle rotation speed at the time of warm air; and, at the time of cold start of the engine, the intake air amount along with the start of firing. A gradually changing means for gradually increasing the metering degree of the engine to a metering degree corresponding to the first idle rotation speed at the time of the cold start. 2. An engine for a vehicle comprising an engine and an electric motor connected to an output shaft thereof, wherein a driving force to drive wheels is sequentially switched from a driving force by the electric motor to a driving force by the engine when starting. Setting means for setting the degree of adjustment of the intake air amount such that the first idle speed at the time of cold start of the engine is higher than the first idle speed at the time of warming up of the engine. During the cold start of the engine, the metering degree of the intake air amount is changed from the metering degree according to the predetermined initial rotation speed to the first idle rotation speed at the cold start with the start of firing. An engine start control device comprising: a gradual change means for gradually increasing the control amount to a corresponding adjustment degree. 3. The engine start control device according to claim 2, wherein the initial rotation speed is a rotation speed given to an output shaft of the engine by the electric motor. 4. The start control device for an engine according to claim 1, wherein a degree of adjustment of the set intake air amount according to a load of the auxiliary device of the engine according to an operation of an auxiliary device of the engine. The engine according to the engine, further comprising a correction unit that performs an increase correction, wherein the gradual change unit sets the gradual change final value to the increase-corrected value when the adjustment degree of the intake air amount is gradually changed. Start control. 5. The engine start control device according to claim 1, wherein said gradual change means changes the gradual change speed in accordance with an operation amount of an accelerator operation means.