JPH10288063A - Idling control device for hybrid engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve the fuel consumption and the exhaust purifying performance by providing an idling control means for stopping the fuel supply to an internal combustion engine at the time of idling and for driving an internal combustion engine with a motor-cum-generator as a motor. SOLUTION: A motor-cum-generator 31 is arranged between an internal combustion engine 1 and a transmission 21, and a magnet rotor of this motor- cum-generator 31 is fixed to a crank shaft of the internal combustion engine 1, and while connected to the transmission 21 through a clutch 22. At the time of performing the idling control of a hybrid engine, in the case where engine speed of the internal combustion engine 1 at the predetermined value or less is detected and where temperature of a catalyst 7 at the predetermined value or more are detected, rotating speed of the motor-cum-generator 31 is controlled at a value smaller than the idling rotating speed at the time of combustion of the internal combustion engine 1 so as to obtain the degree of stability, which is showed with a fluctuation of rotation of the engine, equal to that of the combustion time. With this structure, power consumption of the motor- cum-generator 31 is lowered, and while the fuel consumption is remarkably lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid engine combining an internal combustion engine and a motor / generator.
In particular, it relates to control during idling.

[0002]

2. Description of the Related Art As a conventional hybrid engine,
For example, there is one as shown in FIG. In this embodiment, a motor / generator 52 is interposed between the internal combustion engine 50 and a rotating shaft of a transmission 51, and the internal combustion engine 50 is connected to the motor / generator 52.
And are connected via a clutch (not shown). The motor / generator 52 is driven as a motor by an AC current obtained by converting a DC current from the battery 53 by an inverter 54 (hereinafter referred to as power running). (Hereinafter referred to as regeneration).

[0003] These controls are determined by the controller 55 by inputting the rotation speed and load of the internal combustion engine, and the motor / generator 52 performs power running / regeneration during vehicle operation. At the time of power running of the motor / generator 52, the generated torque of the internal combustion engine 50 is added to the torque, and at the time of regeneration, the torque required for that is subtracted and transmitted to the transmission 51.

The motor / generator 52 is used as a generator at the time of deceleration or low load, and power is run at high load using the energy stored at that time, so-called torque assist is performed on the internal combustion engine 50. The engine 50 can be driven without using it up to the maximum load range. In particular, the purification performance of large-sized diesel internal combustion engines such as NOx and black smoke is improved and the fuel efficiency is improved.

[0005]

However, in such a conventional hybrid engine, a control method is used in which the internal combustion engine is used as a generator at the time of deceleration and low load, and is used as a motor at high load. In particular, in the low-load region where the thermal efficiency of the internal combustion engine is low, the thermal efficiency further deteriorates due to regeneration of the motor / generator, and even in the high-load region where the thermal efficiency is high, the thermal efficiency of the engine is reduced by reducing the load on the internal combustion engine. As a result, the efficiency due to the power running of the motor / generator is not significantly increased, and as a result, there is a problem that the fuel consumption in a certain operation mode is small and the fuel consumption cannot be significantly improved.

The present invention has been made in view of such conventional problems, and provides a hybrid engine that can improve fuel economy by performing appropriate control during idling when the thermal efficiency of the internal combustion engine is the lowest. With the goal.

[0007]

According to the present invention, as shown in FIG. 1, in a hybrid engine in which an internal combustion engine and a motor / generator are combined, fuel is supplied to the internal combustion engine during idling. An idling control means for stopping and rotating the internal combustion engine using the motor / generator as a motor is provided.

There are three types of idling operation modes in a hybrid engine. First
Is a system that idles the internal combustion engine while idling (inertia rotation) the motor / generator, but the thermal efficiency of the internal combustion engine is the lowest at the time of idling, and in the total operation mode, especially in the operation mode including many idling, The fuel consumption is poor and the exhaust purification performance also deteriorates.

The second is a system in which the motor / generator is regenerated as a generator by idling operation of the internal combustion engine. However, the originally poor thermal efficiency further deteriorates due to an increase in load, and the power generation regenerated under such adverse conditions. Even if torque assist of the internal combustion engine is performed at high load with electric power, the thermal efficiency of the internal combustion engine itself is reduced as described above, so that it is not possible to obtain much, and as a result, the fuel efficiency in the operation mode is not improved, and the exhaust purification performance Also worsens as described above.

On the other hand, in the third system of the present invention, when the internal combustion engine having the lowest thermal efficiency is idling, the fuel supply is stopped and the internal combustion engine is driven by the motor / generator. The fuel consumption at the time of operation becomes 0, and even at high load, the internal combustion engine can be operated with high thermal efficiency even if the torque assist by the motor / generator is reduced. Since the emission is 0, the exhaust gas purification performance in the entire operation mode is greatly improved.

In the invention according to claim 2, the idling control means sets a set rotation speed of the motor / generator during the idling to a value smaller than an idling rotation speed during a combustion operation of the internal combustion engine, It is characterized in that the set rotation speed is controlled to be constant. In the case of idling due to the combustion operation of the internal combustion engine, rotation fluctuation due to explosion is involved, so a certain speed or more is required to ensure the stability of rotation, but in comparison with that, the internal combustion engine is driven by a motor and generator. When idling is performed, the stability is higher than in the combustion operation because there is no explosion, and the idling rotation speed for obtaining the same stability as in the combustion operation can be reduced accordingly. Therefore, the set rotation speed during idling by the motor / generator can be set to a value smaller than the idling rotation speed during combustion operation of the internal combustion engine. As a result, the power consumption of the motor / generator can be reduced, and fuel consumption can be reduced. It can be greatly reduced.

Further, the invention according to claim 3 is characterized in that the idling control means performs control so that the rotation speed is gradually decreased by driving only the motor and the generator to approach the set rotation speed. This makes it possible to smoothly change the rotation speed and control the rotation speed to the set rotation speed, thereby avoiding rapid torque fluctuation.

Further, according to a fourth aspect of the present invention, the idling control means includes a step of, when the temperature of the exhaust purification catalyst mounted in the exhaust passage of the internal combustion engine is lower than a set value representing the activation state of the catalyst. It is characterized in that the motor drive of the motor / generator is prohibited, and idling is performed by combustion operation of the internal combustion engine.

When the catalyst temperature has not reached the active state, the combustion operation of the internal combustion engine is carried out, and the drive of the motor / generator is prohibited until the catalyst is heated by the exhaust heat and activated.
By driving the motor / generator after the catalyst temperature becomes active, that is, immediately after switching to the combustion state of the internal combustion engine, a condition for obtaining good exhaust gas purification performance is ensured, the entire operation is improved. Exhaust gas purification performance can be obtained.

According to a fifth aspect of the present invention, the idling control means is configured to output the motor / generator when the temperature of the exhaust purification catalyst mounted in the exhaust passage of the internal combustion engine is higher than a heat resistant limit temperature of the catalyst. Is set to a higher value than when the temperature of the catalyst is equal to or lower than the heat-resistant limit temperature.

With this arrangement, when the temperature of the catalyst is higher than the heat-resistant limit temperature of the catalyst, the set rotation speed of the motor / generator at the time of idling is increased so that the intake and exhaust from the internal combustion engine in the fuel cut state is performed. By increasing the amount of air to be cooled, the amount of cooling of the catalyst by air can be increased, and the temperature can be quickly lowered to the heat-resistant limit temperature or lower. Further, according to a sixth aspect of the present invention, when the driving load of the auxiliary device driven by the internal combustion engine is higher than a predetermined value, the idling control means changes the set rotation speed of the motor / generator to the driving of the auxiliary device. The load is set to a higher value when the load is equal to or less than a predetermined value.

When the driving load of the auxiliary machine is high, the engine speed is stabilized by increasing the rotation speed of the motor / generator.

[0018]

FIG. 2 shows a first embodiment of the present invention. In FIG. 1, an internal combustion engine 1 is supplied with fuel by a fuel injection valve 3 attached to an intake manifold 2, and adjusts an intake air flow rate by a throttle valve 4 attached upstream of the intake manifold 2. Is detected by the air flow meter 10.

The engine control module 11 matches each operating condition based on the opening θ of the throttle valve 4 detected by the throttle opening sensor 5 and the intake air flow rate Q detected by the air flow meter 10. The calculated fuel supply amount is calculated, and a drive pulse signal is output to the fuel injection valve 3 so as to supply the calculated fuel supply amount.

An exhaust gas purifying catalyst 7 is provided in an exhaust passage downstream of the exhaust manifold 6 of the internal combustion engine 1, and the catalyst 7 purifies pollutants in the exhaust gas. The catalyst 7 is provided with a catalyst temperature sensor 8 for detecting a catalyst temperature. A motor / generator 31 is disposed between the internal combustion engine 1 and the transmission 21.
A magnet rotor (not shown) is fixed to a crankshaft of the internal combustion engine 1, and is connected to the transmission 21 via a clutch 22.

The supply of the electric power to the motor / generator 31 and the accumulation of the generated electric power from the motor / generator 31 are performed between the motor / generator 31 and the battery 33 via the inverter 32. The operation state (powering / regeneration) is controlled by the motor control module 34. To the motor control module 34, information on the operating state including the rotation speed N of the internal combustion engine 1 detected by the rotation speed sensor via the engine control module 11 and information on the charge / discharge state of the battery 33 are input.

Auxiliary equipment 9 such as an air conditioner compressor and a power steering is driven by the internal combustion engine 1 via a clutch. Next, the idling control of the hybrid engine having the above configuration will be described. When the engine is idling, power transmission between the internal combustion engine 1 and the motor / generator 31 is cut off from the transmission 21 by the clutch 22. Further, the throttle valve 4 connected to the accelerator pedal (not shown) is located at a position close to substantially fully closed. Hereinafter, specific control during idling will be described with reference to the flowcharts of FIGS.

In step 1, it is determined whether or not the internal combustion engine 1 is performing fuel cut during idling, based on the value of a flag or the like. If it is determined that the fuel is not being cut, the process proceeds to step 2. In step 2, it is detected that the idle switch attached to the throttle sensor 5 is ON, and in step 3, it is detected that the rotation speed of the internal combustion engine 1 detected by the rotation speed sensor is equal to or lower than a predetermined value No. When,
Step 4 when it is determined that the internal combustion engine 1 is in an idle state
Proceed to.

In step 4, the temperature of the exhaust gas purifying catalyst 7 is read from the catalyst temperature sensor 8, and in step 5, it is determined whether or not the temperature of the catalyst 7 is equal to or higher than a set temperature T1 representing the activation state of the catalyst 7. judge. If it is determined in step 5 that the temperature of the catalyst 7 is equal to or higher than the set temperature T1, the process proceeds to step 6, and it is determined whether the temperature of the catalyst 7 is equal to or lower than the heat-resistant limit temperature T2 of the catalyst 7.

If it is determined in step 6 that the temperature of the catalyst 7 is equal to or lower than the heat-resistant limit temperature T2, the temperature of the catalyst 7 is appropriate, and in this state, it is possible to switch to the combustion operation by the internal combustion engine 1 at any time. (Exhaust purification performance can be secured immediately after switching, and overheating of the catalyst can be avoided.) Therefore, in step 7 and subsequent steps, power running by the motor / generator 31 is performed. That is, the rotational speed of the motor / generator 31 is changed to the idling rotational speed N during combustion of the internal combustion engine 1 after step 7.
The rotation speed N2 which is smaller than ei and at which the stability indicated by the rotation fluctuation of the engine or the like becomes the same value as during combustion.
Is controlled so that A comparison between the stability of the motor / generator 31 due to power running (motoring) at the time of the fuel cut and the stability due to combustion operation (firing) of the internal combustion engine 1 is as shown in FIG. It can be seen that the same stability as in combustion can be obtained at a lower rotation speed by motoring. Therefore, the power consumption of the motor / generator 31 can be reduced accordingly, and as a result, the fuel efficiency can be greatly reduced.

The above control will be described in detail. In step 7, the rotational speed Nei of the internal combustion engine 1 during idling is read from the rotational speed sensor 12, and in step 8, the target rotational speed Nmo of the motor / generator 31 is determined. After setting to a value equal to the rotation speed Nei of the internal combustion engine 1 read in step 7, the fuel supply to the internal combustion engine 1 is stopped in step 9, and the target is set in step 10 every cycle measured by the timer 1 in step 12. By reducing the rotation speed Nmo by a predetermined amount α, control is performed to gradually reduce the rotation speed Nm of the motor / generator 31 determined in step 11 to the set rotation speed N2.

On the other hand, if it is determined in step 6 that the temperature of the catalyst 7 is higher than the durability limit temperature T2,
In step 18, the rotation speed Nm of the motor / generator 31
The same control is performed by decreasing the target rotation speed Nmo by a predetermined amount β in each period measured by the timer 2 so that the rotation speed becomes a set rotation speed N4 set higher than the N2. Here, the reason why the rotation speed N4 is set higher than N2 is to cool the catalyst 7 by increasing the amount of air sucked and discharged from the internal combustion engine 1 in the fuel cut state.

When it is determined in step 5 that the temperature of the catalyst 7 is lower than the set temperature T1 representing the activation state of the catalyst, the motor / generator 31 does not drive the motor, and the combustion operation of the internal combustion engine 1 is performed. Perform idling control. That is, in this case, the catalyst 7 is heated by the exhaust heat of the internal combustion engine 1 to promote the activity. After the fuel supply to the internal combustion engine 1 is stopped as described above and the engine is controlled to the set rotation speed N2 or N4 by driving the motor, the process proceeds to step 19 and subsequent steps.

When it is determined in step 19 that the idle switch is OFF, it is determined that the engine is not in the idle state. In addition, the temperature of the catalyst 7 read in step 20 is determined in step 21, and the activation temperature is determined. When it is determined that the temperature has dropped below the representative set temperature T1, the temperature of the catalyst 7 is maintained at or above the activation temperature to secure the exhaust purification performance after the combustion operation is switched by the internal combustion engine 1 in steps 22 and thereafter. Stop the motor drive of the motor / generator 31,
Control for switching to the combustion operation of the internal combustion engine 1 is performed.

More specifically, in step 22, a motor / generator
After reading the rotational speed Nm of the engine 31, the target rotational speed Neo of the internal combustion engine 1 during idling is set in step 23, and the rotational speed Nm of the motor / generator 31 increases to the target rotational speed Neo in the determination of step 24. Until the target rotation speed Neo is increased in step 25 by a predetermined amount γ in each cycle measured by the timer 3 in step 26, the target rotation speed Nmo is determined to have reached the target rotation speed Neo. Then
In step 27, the fuel supply stop of the internal combustion engine 1 is terminated and the fuel supply is restarted, and in step 28, the rotation control of the motor / generator 31 is terminated.

If it is determined in step 21 that the temperature of the catalyst 7 is equal to or higher than the set temperature T1, the process proceeds to step 29 to determine whether the temperature of the catalyst 7 is equal to or lower than the endurance limit temperature T2. Is determined to be equal to or lower than the endurance limit temperature T2, in order to prevent the temperature of the catalyst 7 from unnecessarily lowering, the target rotation speed Nm of the motor / generator 31 is reduced to N2 lower than N4 in step 30. Set to.

Next, at step 31, the value of the auxiliary equipment load flag is read, and at step 32, the auxiliary equipment 9 having a large load such as an air conditioner compressor or power steering driven by a belt or the like by the engine is driven by the value of the flag. It is determined whether or not the vehicle is in the high load state. If it is determined that the vehicle is not in the high load state, the control for maintaining the current target rotation speed Nm is continued. In this case, the routine proceeds to step 33, where the rotational speed N6 necessary for obtaining a stable engine rotation even under the high load condition is obtained.
And calculates the rotation speed N6 as a second target rotation speed Nm2.
Set as

In step 34, the second target rotation speed N
If m2 (= N6) is larger than the target rotation speed Nm up to that point, the routine proceeds to step 35, where the second target rotation speed Nm2 is reset as the target rotation speed Nm.
Here, when Nm is set to N2, Nm2
(= N6)> Nm (= N2), but when the temperature of the catalyst 7 is high and the target rotation speed Nm is set to a relatively large N4, the N6 calculated corresponding to the N4 and the high load is calculated.
The size is a problem.

In step 36, the current rotation speed Nm of the motor / generator is compared with the target rotation speed Nmo, and N
If m <Nmo (Nmo = N6> N2, N4), the target rotational speed Nmo is increased by a predetermined amount n in step 38 in step 38 for each period measured by the timer 4 in step 37. Returning to 36, control is performed to gradually increase the rotation speed Nm of the motor / generator 31 to the target rotation speed Nmo.

If it is determined in step 36 that Nm <Nmo (if Nm is switched from N4 to N2 in step 30), step 39 is executed for each period measured by the timer 1 Target rotational speed Nmo at 40
Is reduced by a predetermined amount n, and the flow returns to step 36 to change the rotation speed Nm of the motor / generator 31 to the target rotation speed Nm.
Control to gradually decrease to o is performed. Control for gradually decreasing the rotation speed to the set rotation speed N2 is performed.

FIG. 7 shows the control during idling of the hybrid engine according to the present invention.
As described above, basically, when the internal combustion engine is idling with the lowest thermal efficiency, by running the motor / generator while the internal combustion engine is in the fuel cut state, both the fuel efficiency and the exhaust gas purification performance can be significantly improved.

Further, by switching the operation between the internal combustion engine and the motor / generator while detecting the temperature of the catalyst and maintaining the catalyst temperature properly, the life of the catalyst is extended and the operation is switched to the operation of the internal combustion engine. Good exhaust gas purification performance can be secured from the beginning. Furthermore, when the target rotation speed changes, the rotation speed is gradually changed so as to converge on the final target rotation speed, so that a smooth driving performance can be ensured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration and functions of the present invention.

FIG. 2 is a diagram showing a system configuration according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a first stage of engine control during idling according to the embodiment;

FIG. 4 is a flowchart showing the latter stage.

FIG. 5 is a flowchart showing a middle stage.

FIG. 6 is a diagram showing a relationship between motor power consumption of the hybrid engine and engine stability during idling in each operating state.

FIG. 7 is a time chart showing an operation switching state during idling according to the embodiment.

FIG. 8 is a diagram showing a system configuration of a conventional hybrid engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Fuel injection valve 7 Exhaust purification catalyst 8 Catalyst temperature sensor 9 Auxiliary equipment 11 Engine control module 31 Motor / generator 34 Motor control module

Claims (6)

[Claims] 1. A hybrid engine in which an internal combustion engine and a motor / generator are combined, comprising idling control means for stopping fuel supply to the internal combustion engine during idling and rotatingly driving the internal combustion engine using the motor / generator as a motor. An idling control device for a hybrid engine. 2. The idling control means sets a set rotation speed of the motor / generator during idling to a value smaller than the idling rotation speed during combustion operation of the internal combustion engine, and controls the set rotation speed to be constant. The idling control device for a hybrid engine according to claim 1, wherein: 3. The hybrid engine according to claim 2, wherein said idling control means controls the motor so that the rotation speed is gradually reduced by driving only a motor / generator to approach a set rotation speed. Idling control device. 4. The idling control means, when the temperature of the exhaust gas purification catalyst mounted in the exhaust passage of the internal combustion engine is lower than a set value representing the activation state of the catalyst, drives the motor / generator to drive the motor. The method according to claim 1, wherein the engine is prohibited and idling is performed by combustion operation of the internal combustion engine.
The idling control device for a hybrid engine according to claim 3. 5. The idling control means according to claim 1, wherein when the temperature of the exhaust gas purification catalyst mounted in the exhaust passage of the internal combustion engine is higher than the heat resistant limit temperature of the catalyst, the idling control means sets the set rotation speed of the motor / generator at idling. The idling control device for a hybrid engine according to any one of claims 1 to 3, wherein the catalyst temperature is set to a higher value when the temperature of the catalyst is equal to or lower than a heat-resistant limit temperature. 6. The idling control means, when the driving load of an accessory driven by the internal combustion engine is higher than a predetermined value, the idling control means sets the rotational speed of the motor / generator to a value equal to or lower than the predetermined value. The idling control device for a hybrid engine according to any one of claims 1 to 5, wherein the idling control device is set to a higher value than in (1).