JP2006283725A - Engine control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel consumption of a vehicle and usability of operation of accessories. <P>SOLUTION: An engine control system controls a main engine 100 driving the vehicle for traveling and a sub engine 200 provided for driving the accessories during stopping of the main engine and having a smaller displacement than the main engine. The engine control device stops fuel supply to the main engine 100 when rotation speed of the main engine 100 is not less than a predetermined rotation speed and is decelerated, starts the fuel supply to the main engine 100 again when the rotation speed of the main engine 100 is decelerated and is lower than the predetermined rotation speed, and continues stopping the fuel supply and drives the sub engine 200 when the vehicle is predicted to stop after deceleration. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine control device that controls a main engine and a sub-engine.

Conventionally, it is known from Patent Document 1 that a small sub-engine for operating an auxiliary machine is provided when the main engine is stopped.
JP 2000-345874 A

  On the other hand, a technique for improving fuel efficiency by stopping fuel supply to the engine with the throttle valve fully closed has been proposed. However, even when the throttle valve is in a fully closed state, normally, control is performed so that fuel supply to the main engine is resumed in order to maintain idle rotation when the rotation speed is lower than a predetermined value. The driving of the main engine by this fuel supply is not used for work at all, so the fuel is wasted.

  The present invention has been made to solve the above-described problems of the prior art, and the object of the present invention is to prevent the main engine from being affected even when the throttle valve is fully closed and the main engine is below a predetermined speed. An object of the present invention is to improve usability while improving fuel efficiency by driving a sub-engine and operating an auxiliary machine without supplying fuel.

In order to achieve the above object, an apparatus according to the present invention provides:
An engine control device that controls a main engine that is driven to drive a vehicle and a sub-engine that has a smaller displacement than the main engine that is provided to drive an auxiliary machine when the main engine is stopped,
The rotational speed of the main engine is equal to or higher than a predetermined rotational speed, and the fuel supply to the main engine is stopped,
When the throttle valve is in a fully closed state, when the main engine speed is lower than the predetermined speed and the vehicle is predicted not to stop, the fuel supply to the main engine is resumed,
When the throttle valve is fully closed and the main engine speed is lower than the predetermined speed and the vehicle is predicted to stop, the sub-engine is driven while the fuel supply is stopped. It is characterized by that.

  According to such control, when the throttle valve is in a fully closed state and the vehicle is predicted to stop, the fuel supply to the main engine is possible even if the rotational speed of the main engine is equal to or less than a predetermined value. The fuel consumption can be improved. In addition, since the sub-engine is driven during that time, when the auxiliary machine is in the operating state, the operating state can be maintained, and even when the auxiliary machine is in the non-operating state, it waits for the start of the operation of the auxiliary machine thereafter. Therefore, there is no problem in the operation of the auxiliary machine, and usability is improved.

  In addition, the sub-engine is driven from the predetermined number of revolutions until the vehicle stops. However, the sub-engine is smaller than the main engine and has less mechanical resistance and pumping loss, so the main engine is driven. Compared to the case, fuel consumption can be greatly improved.

  If the throttle valve is fully closed, the main engine speed is lower than the predetermined speed, and the vehicle is predicted to stop, but the auxiliary machine is not in operation, The engine is not driven. When the auxiliary machine is not in the operating state, the sub-engine is not driven, so that the fuel consumption can be further improved.

Even when the throttle valve is fully closed, the rotation speed of the main engine is lower than the predetermined rotation speed, and the vehicle is predicted to stop, the auxiliary load is not more than the predetermined value. The sub-engine is not driven. When the load applied to the auxiliary machine is less than or equal to a predetermined value, the sub-engine is not driven, so that the fuel consumption can be further improved. ,
The main engine is automatically stopped while the vehicle is stopped. In other words, the fuel consumption can be further improved by performing the idle stop control.

  ADVANTAGE OF THE INVENTION According to this invention, the improvement of the usability about auxiliary machinery operation | movement can be aimed at, improving the fuel consumption of a vehicle.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the constituent elements described in this embodiment are merely examples, and are not intended to limit the scope of the present invention only to them.

<Embodiment>
(Constitution)
A configuration in an engine room to which an exhaust purification system according to an embodiment of the present invention is applied will be described with reference to FIG. FIG. 1 is a diagram showing a layout of the main engine 100, the sub-engine 200, and the peripheral configuration thereof.

  The main engine 100 is for use when the vehicle travels, and has an exhaust amount of 2000 cc, for example, according to the capacity of the vehicle. On the other hand, the sub-engine 200 is provided to drive the auxiliary machine 150 under a predetermined condition, for example, in a state where the main engine 100 is stopped, such as during idling. The auxiliary machine 150 here is an apparatus such as an air conditioner or a power steering pump that causes inconvenience to the occupant, such as when the operation of the main engine 100 is stopped and the operation of the main engine 100 is stopped, the air conditioning does not work or the steering resistance increases. . The sub-engine 200 has a displacement of 50 cc, for example, according to the load of the auxiliary machine to be driven.

  A main exhaust passage 300 is provided to guide the exhaust gas discharged from the main engine 100 to the outside of the vehicle. On the main exhaust passage 300, exhaust purification sections 400A and 400B for purifying exhaust gas are provided. The exhaust purification units 400A and 400B include a three-way catalyst in which a noble metal such as platinum or rhodium is supported on a base, and the air-fuel ratio of the exhaust gas introduced into the exhaust purification units 400A and 400B is the stoichiometric air-fuel ratio (λ = 1), air pollutants such as NOx (nitrogen oxide), CO (carbon monoxide), and HC (hydrocarbon) are purified. 1 shows two exhaust purification sections 400A and 400B, three or more may be provided. Exhaust gas discharged from the sub-engine 200 is guided between the plurality of exhaust purification units 400A and 400B by the sub-exhaust passage 500. Then, the sub-engine control unit 600 that controls the sub-engine 200 drives the sub-engine 200 in order to warm the exhaust purification unit 400B located downstream of the connection end 500a of the sub-exhaust passage 500.

  The catalyst used in the exhaust purification units 400A and 400B cannot fully exhibit the exhaust gas purification power unless the temperature reaches the activation temperature. Therefore, at the time of cold start of the engine in which the exhaust purification catalyst is not activated, the sub-engine 200 is driven particularly in order to effectively warm up the exhaust purification section 400B at the rear stage. Thus, after the engine is started, the exhaust heat from the sub-engine 200 can be used to activate the exhaust purification unit 400B at an early stage, thereby improving the exhaust purification performance and reducing the cost of the exhaust purification unit.

  The sub-engine control unit 600 controls the sub-engine 200 until the exhaust purification unit 400A located upstream of the connection end 500a of the sub-exhaust passage 500 reaches a predetermined activation temperature among the plurality of exhaust purification units 400A and 400B. To drive. As shown in FIG. 2, this is based on the phenomenon that the temperature of the upstream exhaust purification unit 400B starts to rise after the temperature of the exhaust purification unit 400A on the upstream side is almost searched and warmed up completely. is there.

  After the time point T1 when the temperature of the upstream side exhaust purification unit 400A has almost increased, the exhaust gas exhausted from the upstream side exhaust purification unit 400A has a sufficient amount of heat, and therefore, the downstream side exhaust purification unit 400A. The temperature of the part 400B rises rapidly. Therefore, the sub-engine control unit 600 drives the sub-engine 200 until T1, and raises the temperature of the downstream exhaust purification unit 400B as indicated by a one-dot chain line. To stop. That is, after the engine is started and until T1 elapses, both main engine 100 and sub-engine 200 perform combustion, and after T1 elapses, only main engine 100 performs combustion.

  Further, sub engine control unit 600 determines whether or not T1 has elapsed based on whether or not the accumulated fuel consumption after starting main engine 100 has reached a predetermined value. The fuel consumption amount is obtained by integrating the fuel injection amount every time calculated to be injected from the injector 800 from a fuel tank (not shown) by the main engine control unit 700. Then, the accumulated fuel consumption is derived by integrating the fuel consumption. The amount of heat proportional to the accumulated fuel consumption is generated in the main engine 100, and the amount of heat proportional to the amount of heat generated in the main engine 100 is discharged as exhaust gas. As a result, the temperature rise of the exhaust purification units 400A and 400B This is proportional to the accumulated fuel consumption.

  In this way, the accumulated fuel consumption is regarded as the amount of heat, and by determining the accumulated fuel consumption until a sufficient amount of heat is transmitted to the downstream exhaust purification unit that is warmed by the driving of the sub-engine, a temperature sensor is provided to the exhaust purification unit. Even without mounting, it is possible to more easily control the drive of the appropriate sub-engine 200, and to effectively activate the exhaust purification unit early.

  Sub engine control unit 600 does not drive sub engine 200 when the engine water temperature at the start is equal to or higher than a predetermined temperature. If the engine water temperature is high when the main engine 100 is started, there is a high possibility that the temperature of the exhaust purification unit 400B is also maintained at a high state, so it is determined that there is no need to warm the sub-engine 200. Therefore, the sub-engine 200 is not wastefully driven, and the exhaust purification unit can be activated quickly and efficiently.

  The main engine 100 is provided with a main engine control unit 700 for controlling the rotation speed and torque of the main engine 100. The main engine control unit 700 is configured so that when the sub engine control unit 600 stops driving the sub engine 200, the generated torque of the main engine 100 increases by an amount necessary for driving the auxiliary machine. Control the drive.

  According to this configuration, when stopping the sub-engine 200, it is possible to prevent the load for driving the auxiliary equipment from being shifted to the main engine 100 side and the torque of the main engine 100 to be rapidly reduced.

(control)
Next, control in the embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram for explaining changes in the vehicle speed 201 and the engine speed 202 until the vehicle stops and the engine stops during operation with the throttle valve fully closed.

  First, as a premise of the control of the present embodiment, a so-called idle stop technique is known in which the engine is stopped and the fuel consumption is improved while the vehicle is stopped. However, if the engine is completely stopped, the operation of auxiliary equipment such as an air conditioner cannot be maintained properly. Therefore, when the engine is stopped while the auxiliary machine is operating, the air conditioner is not effective, and other problems due to the stoppage of the auxiliary machine operation have occurred. Therefore, the sub-engine 200 shown in FIG. 1 is driven and used to operate the auxiliary machine 150 while the main engine 100 is stopped.

  On the other hand, there has also been proposed a technique for improving fuel consumption by stopping fuel supply to the main engine 100 in a state where the throttle valve is fully closed (during so-called deceleration operation). The fuel supply stop at the time of the deceleration operation is normally such that the fuel supply is resumed when the engine speed decreases to a fuel return speed set higher than the idle speed by a predetermined speed (for example, 100 rpm). It has become. This is for returning to idle operation when the vehicle stops.

  However, in the above-described vehicle with an idle stop, after the fuel is returned, when the vehicle speed becomes 0 and the vehicle stops, the engine is stopped again. Therefore, the period from the fuel return until the vehicle stops. Therefore, it is not necessary to maintain the predetermined rotational speed, and on the contrary, useless fuel consumption is performed.

  This state is shown in FIG. When the throttle valve is fully closed, the engine speed 202 decreases as the vehicle speed 201 decreases. At this time, in order to improve fuel consumption, the fuel supply to the main engine 100 is stopped (fuel cut flag 204 → 1).

  However, conventionally, since it is necessary to maintain the idling speed, the fuel supply to the main engine 100 is resumed and the idling speed is maintained when the fuel return speed 205 reaches about 100 rpm higher than the idling speed 203. (Fuel cut flag 204 → 0). However, since the energy obtained by idling driving the main engine 100 is extremely large compared to the energy for driving the auxiliary machinery, it has caused a reduction in fuel consumption (shaded portion).

  On the other hand, in a vehicle equipped with the sub-engine 200 as in the present embodiment, the sub-engine 200 can be used to drive the auxiliary machine. The fuel supply to the main engine 100 can be stopped until the engine is stopped. In other words, if it is assumed that the vehicle will stop after the deceleration fuel supply is stopped, for example, if the brake is depressed and the vehicle is expected to stop, the fuel supply will continue to stop until the vehicle stops. What is necessary is just to drive the sub-engine 200 for an auxiliary machine action | operation.

  As described above, when the sub-engine 200 is driven under the condition that the main engine 100 is in the fuel supply stop operation and the rotation speed of the main engine 100 is equal to or lower than the predetermined fuel return rotation speed 205, the rotation speed of the main engine 100 is increased. It is possible to compensate for a shortage of auxiliary machine drive energy due to the decrease to the idling speed 203 or less. Therefore, even if the auxiliary machine, for example, the air conditioner is in an operating state, even if the fuel supply is stopped, the adverse effect such as the ineffective air condition does not occur, and usability can be improved. Further, in this figure, since the sub engine 200 is always driven regardless of the operation state of the auxiliary machine, even when the operation of the auxiliary machine requiring immediate responsiveness such as a power steering pump is started, the sub engine 200 is started. Since the operation start delay can be suppressed and the auxiliary equipment can be prevented from being delayed, usability can be improved.

  In this figure, if the throttle valve is fully closed, the fuel supply is stopped, and the rotation speed of the main engine 100 is equal to or lower than the predetermined value 205, the sub-engine 200 is always operated. Although it is supposed to be driven, the present invention is not limited to this. For example, the operating status of the auxiliary machine may be monitored, and the sub-engine 200 may not be driven unless the auxiliary machine is operating. That is, the fact that the auxiliary machine is operating may be added to the driving condition of the sub-engine 200.

  Furthermore, it may be added as a sub-engine driving condition that the auxiliary machine load is a predetermined value or more. That is, if the auxiliary machine load is not equal to or greater than a predetermined value, the sub-engine 200 may not be driven even if the rotational speed of the main engine 100 decreases.

  4 to 6 are flowcharts showing the flow of control performed by the sub-engine control unit 600 and the main engine control unit 700. A series of processing shown in this flowchart is periodically performed while the main engine is driven.

  First, in step S401 in FIG. 4, it is determined whether or not an idle stop preparation condition is satisfied. The idle stop preparation conditions include the following.

・ Throttle valve fully closed ・ Brake is depressed ・ Winker is not operated ・ Power steering pump is not operated ・ Vehicle speed has exceeded a predetermined value after engine startup ・ Engine water temperature is above a predetermined value ・A predetermined time has elapsed since the engine was started.The battery voltage is higher than a predetermined value.The battery is not deteriorated.The catalyst temperature is higher than a predetermined value.The AT oil temperature is within a predetermined range. In a state where all these conditions are satisfied, it is considered that the idle stop preparation condition is satisfied, and the process proceeds to step S402, where the idle stop preparation flag is set to 1. If any of the above conditions is not satisfied, the process proceeds to step S403 and the idle stop preparation flag is set to zero.

  In step S404, it is determined whether or not the vehicle speed is zero. If the vehicle speed is 0, the process proceeds to step S405, and the idle stop execution flag is set to 1. On the other hand, if the vehicle speed is not 0, the idle stop execution flag is set to 0 and the process is terminated.

  Next, determination of the fuel cut permission condition will be described with reference to FIG. In step S501, it is determined whether or not a deceleration fuel cut permission condition is satisfied. If it is satisfied, the process proceeds to step S502, and the fuel cut permission flag is set to 1. If the deceleration fuel cut permission condition is not satisfied, the process proceeds to step S503, and the fuel cut permission flag is set to zero.

  The deceleration fuel cut permission conditions include the following.

・ Throttle valve fully closed ・ Predetermined time has elapsed since engine startup ・ Predetermined time has elapsed after shift ・ Airflow sensor is not broken In other words, deceleration fuel is satisfied when all of these conditions are satisfied. It is considered that the cutting permission condition is satisfied. On the other hand, when any of these conditions is not satisfied, it is considered that the deceleration fuel cut permission condition is not satisfied.

  Next, stop control of the main engine 100 and the sub-engine 200 will be described with reference to FIG.

  First, in step S601, it is determined whether or not the idle stop execution flag is 1. If it is 1, the process proceeds to step S617 and the main engine 100 is stopped. Thereafter, the process proceeds from step S619 to step S607 or S621 in accordance with the auxiliary machine operating state, and the sub-engine is driven or stopped.

  On the other hand, if the idle stop execution flag is 0, the process proceeds from step S601 to step s603, where it is determined whether the deceleration fuel cut permission flag is 1. When the deceleration fuel cut permission flag is 0, the normal operation is performed without performing the fuel cut operation, so the process proceeds to step S605, the main engine 100 is driven, and the process proceeds to step S607 to stop the sub-engine 200. .

  If it is determined in step S603 that the fuel cut permission flag is 1, the process proceeds to step S609, where it is determined whether the engine speed of the main engine 100 is lower than the fuel return speed. If the engine speed is equal to or higher than the fuel return speed, the process proceeds to step S611 to stop the main engine 100, and further proceeds to step S607 to stop the sub-engine 200 and terminate the process.

  On the other hand, if the engine speed is lower than the fuel return speed, the process proceeds to step S613 to determine whether the idle stop preparation flag is 1 or not. If the idle stop preparation flag is not 1, the process proceeds to step S615, the main engine 100 is driven, and the process proceeds to step S607 to stop the sub-engine 200.

  If it is determined in step S613 that the idle stop preparation flag is 1, the process proceeds to step S617 and the main engine 100 is stopped. If the main engine 100 is stopped in step S617, the process proceeds to step S619, where it is determined whether the auxiliary machine 150 is in an operating state. If not, the process proceeds to step S607 and the sub-engine 200 is stopped. If the auxiliary machine 150 is in the operating state, the process proceeds to step S621 to drive the sub engine 200 and supply the energy of the sub engine 200 to the auxiliary machine 150.

  By performing the driving process of the main engine 100 and the sub-engine 200 according to the above flowchart, it is possible to compensate for the shortage of auxiliary machine operating energy during the fuel supply stop operation for the main engine 100. Therefore, even if the auxiliary machine, for example, the air conditioner is in an operating state, even if the fuel supply is stopped, the adverse effect such as the ineffective air condition does not occur, and usability can be improved. In this flowchart, it is determined in step S619 that the auxiliary machine 150 is operating, and the process proceeds to step S621 on the condition that the auxiliary machine 150 is operating, and the sub-engine 200 is driven. As described above, the sub engine 200 may be driven regardless of whether or not the auxiliary machine is in operation, or the sub engine 200 is driven on the condition that the auxiliary machine load is equal to or greater than a predetermined value. Also good. That is, in a modified example in which the process of step S619 is not performed, or in step S619, it is determined whether the load necessary for operating the auxiliary machine 150 is equal to or greater than a predetermined value. A modification in which the sub-engine 200 is driven by proceeding to FIG.

  As described above, in the present embodiment, when the fuel supply to the main engine 100 is stopped during deceleration, the sub-engine control unit 600 drives the sub-engine 200 under a predetermined condition. It is possible to improve the usability of machine operation. Specifically, if the vehicle is predicted to stop as it is during deceleration and the rotational speed of the main engine 100 becomes a predetermined value or less, the main engine 100 is driven while the sub-engine 200 is being driven. The fuel supply to is stopped.

It is a figure which shows the structure of the engine control apparatus as embodiment of this invention. It is a figure which shows the temperature change of an upstream exhaust gas purification part and a downstream exhaust gas purification part. It is a figure which shows operation | movement of the engine control apparatus as embodiment of this invention. It is a flowchart which shows operation | movement of the engine control apparatus as embodiment of this invention. It is a flowchart which shows operation | movement of the engine control apparatus as embodiment of this invention. It is a flowchart which shows operation | movement of the engine control apparatus as embodiment of this invention.

Explanation of symbols

100 Main engine 150 Auxiliary machine 200 Sub engine 300 Main exhaust passage 400 Exhaust purification unit 500 Sub exhaust passage 600 Sub engine control unit 700 Main engine control unit 800 Injector

Claims (5)

An engine control device that controls a main engine that is driven to drive a vehicle and a sub-engine that has a smaller displacement than the main engine that is provided to drive an auxiliary machine when the main engine is stopped,
If the rotational speed of the main engine is equal to or higher than the predetermined rotational speed and the throttle valve is fully closed, the fuel supply to the main engine is stopped,
When the throttle valve is in a fully closed state, when the main engine speed is lower than the predetermined speed and the vehicle is predicted not to stop, the fuel supply to the main engine is resumed,
When the throttle valve is fully closed and the main engine speed is lower than the predetermined speed and the vehicle is predicted to stop, the sub-engine is driven while the fuel supply is stopped. An engine control device characterized by that.   If the throttle valve is fully closed, the main engine speed is lower than the predetermined speed, and the vehicle is predicted to stop, but the auxiliary machine is not in operation, The engine control device according to claim 1, wherein the engine is not driven.   Even when the throttle valve is fully closed, the rotation speed of the main engine is lower than the predetermined rotation speed, and the vehicle is predicted to stop, the auxiliary load is not more than the predetermined value. The engine control device according to claim 1, wherein the sub-engine is not driven.   The engine control device according to claim 1, wherein the main engine is automatically stopped while the vehicle is stopped.   The engine control apparatus according to claim 1, wherein the vehicle is predicted to stop when the brake of the vehicle is operating.

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