JP2830044B2 - Internal combustion engine speed control system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotational speed control device for an internal combustion engine,
More particularly, the present invention relates to a rotation speed control device that regulates an allowable upper limit rotation speed of the engine when the engine is cold immediately after starting.

(Prior art) The internal combustion engine is required to keep the engine speed below the allowable upper limit speed due to the operating limit of the valve operating mechanism, the vehicle speed limit under the regulation, and the boost pressure limit of the internal combustion engine equipped with a turbocharger. Has restricted. In order to regulate the engine overspeed, when the internal combustion engine exceeds the allowable upper limit rotational speed, the engine speed is set by stopping the supply of fuel by a rotational speed limiting means, for example, a fuel injection valve. The number of rotations is limited to below.

(Problems to be Solved by the Invention) Such a conventional engine speed control device considers the speed limit when the engine is warmed up, and the engine is not sufficiently warmed immediately after a cold start or the like. In this state, even if the engine speed is within the conventional allowable upper limit speed, abnormal operating wear of the engine sliding part occurs under operating conditions such as high speed, high load, and high supercharging pressure. There is a risk of serious damage.

On the other hand, even immediately after the start of the engine, sudden start or acceleration may be necessary.Since the engine is cold, simply set the allowable upper limit of the engine speed to a lower value. May not be possible.

The present invention has been made in order to solve such a problem, and an internal combustion engine which prevents abnormal wear of the engine at the time of cold operation, such as immediately after the start of the internal combustion engine, without excessively reducing drivability. A cold state detecting means for detecting a cold state; a load detecting means for detecting an engine load of the internal combustion engine; and an upper limit rotation for setting an allowable upper limit rotational speed of the engine according to the cold state of the engine detected by the cold state detecting means. The number setting means, the upper limit rotation speed correcting means for correcting the allowable upper limit rotation speed set by the upper limit rotation speed setting means according to the engine load detected by the load detecting means, and the upper limit rotation speed correcting means. Rotation speed limiting means for limiting an increase in the rotation speed of the internal combustion engine so as to be less than the allowable upper limit rotation speed. Speed control system for combustion engine is provided.

(Operation) The cold state of the engine is detected by a cold state detecting means, for example, an engine cooling water temperature sensor or an intake air temperature sensor, or a timer for measuring an elapsed time from the start point, and the engine is detected by these cold state detecting means. An allowable upper limit rotational speed is set according to the cold state. And
When the engine speed rises beyond the set allowable upper limit speed, the fuel supply is stopped by the speed control means that stops the fuel supply, stops the high voltage supply to the spark plug, and relieves the supercharging pressure. The engine speed is regulated to be equal to or less than the set allowable upper limit speed.

At this time, when the allowable upper limit rotational speed is corrected according to the engine load detected by the load detecting means for detecting the engine load such as the throttle valve opening, the intake negative pressure, and the fuel supply amount,
Excessive deterioration of drivability is prevented.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration of a rotational speed control device for an internal combustion engine according to the present invention. In FIG. 1, reference numeral 1 denotes, for example, a four-cylinder gasoline engine, and an intake passage 2 is connected to each cylinder of the engine 1. . An air cleaner 3 is attached to an end of the intake passage 2 which is open to the atmosphere, and a throttle valve 4 is provided in the middle thereof.

Each cylinder 1a of the engine 1 is provided with a spark plug 9 for igniting the air-fuel mixture in the cylinder 1a. The spark plug 9 is connected to the electronic control unit 10 via a distributor 16, an ignition coil 17, and a drive circuit 18. Connected to the output side. The drive circuit 18 supplies a primary voltage to the ignition coil 17 according to a control signal supplied from the electronic control unit 10, and the ignition coil 17 generates a secondary high voltage when the supply of the primary voltage is stopped.

A fuel injection valve 20 mounted near the intake port of each cylinder 1a is connected to the output side of the electronic control unit 10, and the required amount of fuel is opened by a valve opening drive signal from the electronic control unit 10. Is injected and supplied to each cylinder 1a.

On the other hand, on the input side of the electronic control unit 10, various sensors for detecting the operating state of the engine 1, for example, mounted near the open end of the intake passage 2 and detecting a Karman vortex, generate a frequency pulse f proportional to the air flow rate. , An intake air temperature sensor 23 provided in the air cleaner 3 for detecting the intake air temperature Ta, a throttle opening sensor 24 for detecting the opening θth of the throttle valve 4, and detecting a predetermined crank angle position. A crank angle sensor 26, a water temperature sensor 28 for detecting a cooling water temperature Tw of the engine 1, a start switch sensor (not shown) for detecting an on / off state of an ignition key switch, an atmospheric pressure sensor for detecting atmospheric pressure, and an operating state of an air conditioner. Air conditioner switch,
A battery sensor or the like for detecting a battery voltage is connected, and these sensors supply a detection signal to the electronic control unit 10.

The electronic control unit 10 calculates the fuel injection amount according to the engine operating state based on the detection signals of the various sensors described above, that is, calculates the valve opening time of the fuel injection valve 20, and generates a drive signal corresponding to the calculated valve opening time. The fuel is supplied to each fuel injection valve 20 to be opened, and a required amount of fuel is injected and supplied to each cylinder. In addition, the ignition timing according to the engine operating state is calculated, a control signal corresponding to the calculated ignition timing is supplied to the drive circuit 18, a high voltage is generated in the ignition coil 17, and the mixture supplied to each cylinder is calculated. Ignite.

Next, with reference to the flowchart shown in FIG. 2, a description will be given of a rotational speed control procedure immediately after starting by the rotational speed control device.
In this embodiment, the cold state of the engine is determined by the engine cooling water temperature.
In addition to the detection by Tw, the engine load is detected by the throttle valve opening θth.

More specifically, the electronic control device 10 firstly
The engine cooling water temperature Tw detected by the water temperature sensor 28, the engine speed Ne detected by the crank angle sensor 26, and the throttle valve opening θth detected by the throttle opening sensor 24 are read (step S20), and the detected engine cooling water temperature Tw is read.
And the fuel cutoff engine speed according to the throttle valve opening θth (the permissible upper limit rotational speed) N _FC, read from the map stored in the storage device of the electronic control unit 10 (step S2
2).

FIG. 3 shows a fuel cut rotation speed map stored in the above-mentioned storage device. As the engine cooling water temperature Tw becomes lower,
Fuel cutoff engine speed N _FC is set to a low value. Moreover, during high-load operation in which the throttle valve 4 is increased opened, according to the throttle valve opening [theta] th, are corrected to a larger value of the fuel cut-off rotation speed N _FC scope serious engine damage does not occur. Even if the engine wear is large, the position of the engine driver is respected so that the drivability is not excessively deteriorated. In the third diagram, when the throttle valve opening θth is smaller than a predetermined value theta _1, small opening, is smaller than the predetermined value theta ₂ at a predetermined value theta ₁ or more, mid opening amount, when _two or more predetermined value theta , Is defined as a large opening.

Next, the process proceeds to step S24, where the engine speed Ne is
It is determined whether or not higher than the fuel cut-off rotation speed N _FC read, the process proceeds to step S26 to be high, the valve opening time T _INJ is calculated, the normal fuel supply is performed. On the other hand, when the engine speed Ne is higher than the fuel cut-off rotation speed N _FC, the step S28 is executed, the driving signals to the fuel injection valve 9 is output, fuel cut is performed. Therefore, the engine speed Ne can not rise beyond the fuel cutoff engine speed N _FC, it would be limited to this speed.

FIG. 4 shows a second embodiment of the present invention, in which the cooling state of the engine 1 is determined by a cooling water temperature Tw detected immediately after the engine,
The engine load is detected by the elapsed time from the start time, and the engine load is detected by the throttle valve opening θth.

More specifically, the electronic control unit 10 firstly controls the throttle valve opening θth detected by the throttle opening sensor 24, the engine speed Ne detected by the crank angle sensor 26, and the engine cooling water temperature Tw detected by the water temperature sensor 28. read (step S40), among these, are detected during startup, the fuel cut-off rotation speed N _FC according to the elapsed time from the cooling water temperature T _WO and a starting point stored in the storage device, stored in the storage device The data is read from the map (step S42).

Figure 5 shows a fuel cut-off rotation speed map stored in the aforementioned memory storage, a fuel cut-off rotation speed N _FC, the low engine coolant temperature T _WO at the time of starting, and, the elapsed time from the start time point The shorter the value, the lower the value.

Next, it is determined whether or not the throttle valve opening θth is opened to be larger than the predetermined value θa (step S4).
Four). This determination is for ensuring drivability. When the throttle valve 4 is largely opened (the determination result is affirmative), the fuel cut speed is set within a range that does not cause serious damage to the engine. the N _FC, as described later, is changed corrected to a larger value (step S4
Five).

Figure 6 shows a table used when setting the corrected fuel cutoff engine speed N _FC at step S45, the engine coolant temperature Tw is a predetermined temperature (e.g., -10 ° C.) as a reference, in the following cases than this Is a predetermined value, for example, 7500 rpm
In the above case, the value is corrected to a predetermined value, for example, 8000 rpm. It should be noted that the finally set fuel cut speed N
_{As FC} , the larger value between the value set from the map in FIG. 5 and the value set from the table in FIG. 6 is selected.

Then, the process proceeds to a step S46, the engine rotational speed Ne is determined whether or not higher than the fuel cut-off rotation speed N _FC, which is set as described above, be high proceeds to step S48, the
The valve opening time T _INJ is calculated, and normal fuel supply is performed.
On the other hand, the engine speed Ne when it is higher than the fuel cut-off rotation speed N _FC is determined, step S49 is executed, the driving signals to the fuel injection valve 9 is not output, fuel cut is performed.

FIG. 7 shows a third embodiment of the present invention, in which the engine cooling state is detected based on the engine cooling water temperature Tw as in the first embodiment, and the engine load is detected based on the throttle valve opening θth. is there. The fuel cutoff engine speed N _FC, which is set is corrected in accordance with the intake air temperature Ta.

More specifically, the electronic control unit 10 firstly includes a water temperature sensor
The engine cooling water temperature Tw detected by 28, the throttle valve opening θth detected by the throttle opening sensor 24, the engine speed Ne detected by the crank angle sensor 26, and the intake temperature Ta detected by the intake temperature sensor 23 are read ( Step ns7
0), depending on the detected engine coolant temperature Tw and a throttle valve opening [theta] th, reads the fuel cutoff engine speed N _FC from the map of FIG. 3 described above (step S72). The fuel cutoff engine speed N _FC, the lower the street engine coolant temperature Tw as described above, the fuel cut-off rotation speed N _FC is set to a low value, and when the throttle valve 4 is increased valve opening, according to the throttle valve opening [theta] th, are corrected to a larger value of the fuel cut-off rotation speed N _FC scope serious engine damage does not occur.

Next, the electronic control unit 10 determines whether the intake air temperature Ta is lower than a predetermined temperature (for example, −10 ° C.) Tao (step s7).
Four). This determination is intended to determine the cold state of the engine more accurately, (if determination result is affirmative) intake air temperature Ta is in the case lower than the predetermined value T _a0, according to the fuel cutoff engine speed N _FC in the intake air temperature Ta Is modified (step s75).

Figure 8 shows a table used when setting the corrected fuel cutoff engine speed N _FC at step S75, the intake air temperature Ta is a predetermined temperature (e.g., -20 ° C.) a predetermined value in the case of T _a1 or less, for example, to 8000 rpm, higher than the predetermined value T _a1, when the predetermined value T _a0 less is corrected to a predetermined value, for example 8500 rpm. The fuel cutoff engine speed N _FC is finally set in this case, the value of the smaller value is set from the values and Figure 8 table set from the map of FIG. 3 is selected.

Then, the process proceeds to a step S76, the engine rotational speed Ne is determined whether or not higher than the fuel cut-off rotation speed N _FC, which is set as described above, be high proceeds to step S78,
The valve opening time T _INJ is calculated, and normal fuel supply is performed.
On the other hand, the engine speed Ne is the higher the fuel cutoff engine speed N _FC is determined, step S79 is executed, the driving signals to the fuel injection valve 9 is not output, fuel cut is performed.

In the above three embodiments, the supply of fuel is stopped to limit the engine speed Ne to the allowable upper limit speed. However, the present invention is not limited to this. For example, the drive circuit 18 shown in FIG.
The engine speed Ne can be limited to the allowable upper limit speed by not outputting a control signal to the engine and not igniting the air-fuel mixture.

In addition, in an internal combustion engine equipped with a turbocharger, the supercharging pressure is adjusted by opening and closing the wastegate and bypassing part of the exhaust gas through the turbocharger,
Thus, it is possible to limit the engine speed Ne to the allowable upper limit speed or less. In this case, it is desirable to open the wastegate at a lower boost pressure as the engine cooling water temperature Tw is lower.

Further, the load detecting means for detecting the load on the engine is not limited to the throttle opening sensor for detecting the throttle valve opening described above, but may be a negative pressure sensor for detecting a negative pressure in the intake passage downstream of the throttle valve. Alternatively, the load may be detected from the amount of fuel supplied to the engine. Further, the engine load may be detected from the intake air amount per intake stroke, and the allowable upper limit rotational speed may be corrected in the same manner as in the above-described embodiment according to the engine load detected by these sensors. I just need.

(Effects of the Invention) As described in detail above, according to the internal combustion engine speed control apparatus of the present invention, the allowable upper limit engine speed is set according to the cold state of the engine detected by the cold state detecting means. Since the engine speed is controlled to be equal to or less than the set allowable upper limit speed by the speed control means, abnormal wear of the engine can be prevented, and the engine life can be significantly extended. In addition, since the allowable upper limit rotational speed is corrected in accordance with the engine load detected by the load detecting means, abnormal wear of the engine at the time of cold can be prevented without excessively deteriorating drivability. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a rotation speed control device for an internal combustion engine according to the present invention, FIG. 2 is a flowchart showing a rotation speed control procedure of the first embodiment, and FIG. the electronic control unit is stored in a storage device 10, the map showing a fuel cutoff engine speed N _FC to be read in accordance with the engine coolant temperature Tw and the throttle valve opening [theta] th, Figure 4 is the speed of the second embodiment shown FIG. 5 is a flowchart showing the control procedure, and FIG. 5 is stored in the storage device of the electronic control unit 10 shown in FIG. 1 and is read out according to the engine cooling water temperature Tw detected immediately after the start and the elapsed time from the start time. map showing a fuel cutoff engine speed N _FC, FIG. 6 is stored in the storage device of the electronic control device 10 shown in FIG. 1, modified according to the engine coolant temperature Tw to the high load of the throttle valve is largely opened Te fuel cutoff engine speed N _FC is Table 3 and Fig. 7
Flowchart showing the rotational speed control procedure of the eighth embodiment, FIG.
The figure shows the fuel cut speed N corrected according to the intake air temperature Ta.
It is a table figure of _FC . DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Intake passage, 3 ... Throttle valve, 9 ... Spark plug, 10 ... Electronic control unit (ECU), 20
... fuel injection valve, 22 ... air flow sensor, 23 ... intake air temperature sensor, 24 ... throttle opening sensor, 26 ... crank angle sensor, 28 ... water temperature sensor.

Claims (1)

(57) [Claims] A cooling state detecting means for detecting a cooling state of the internal combustion engine; a load detecting means for detecting an engine load of the internal combustion engine; an engine according to a cooling state of the engine detected by the cooling state detecting means. Upper limit rotational speed setting means for setting an allowable upper limit rotational speed of the engine, and upper limit rotational speed correcting means for correcting the allowable upper limit rotational speed set by the upper limit rotational speed setting device in accordance with the engine load detected by the load detecting means. And rotation speed regulating means for restricting an increase in the rotation speed of the internal combustion engine so as to be equal to or less than the allowable upper limit rotation speed corrected by the upper limit rotation speed correcting means. Control device.