JPS6329101B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to an idle speed control device for an internal combustion engine used in an automobile or the like. [Prior art] In automobiles, the engine speed during idle is compared with the target idle speed, and the throttle valve opening is changed according to the deviation to control the engine speed to the target speed. Some vehicles are equipped with an idle speed control device designed to reduce fuel consumption. By the way, in a car, when the accelerator pedal is released and the vehicle is decelerating from a high-speed driving state to a low-speed driving state, the engine side is driven from the wheel side. Since the opening is the same as when idling, a constant amount of fuel is still supplied from the upstream side of the throttle valve. Therefore, if such deceleration driving continues and is repeated, the fuel supplied to the engine combustion chamber becomes slightly excessive, causing incomplete combustion, and the incomplete combustion gas is combusted in the three-way catalyst. This causes a problem in that the temperature of the three-way catalyst rises abnormally, eventually destroying its function. However, conventional idle speed control devices do not control the air-fuel ratio during deceleration, and although the same throttle valve opening is controlled, a dedicated control device for deceleration does not. It was controlled. As a result, the engine control system became complicated and the cost increased. [Summary of the Invention] The present invention has been made to solve the above-mentioned problems.The purpose of the present invention is to provide an inexpensive structure, set the engine rotation speed at idle to a target rotation speed, and set the engine rotation speed at the time of deceleration to a An object of the present invention is to provide an idle rotation speed control device for an internal combustion engine that can also prevent abnormal temperature rise of a main catalyst. To this end, the present invention provides, in addition to an actuator that variably controls the throttle valve opening, a position detection means that detects the drive position of the actuator, and when idling, the actuator is configured to control the actuator so that the engine speed converges to the target rotation speed. The actuator is configured to drive the actuator so that during deceleration, the throttle valve opening is set to an optimum opening, which is smaller than when idling, based on the detection output of the position detection means, which is determined in relation to the allowable temperature of the three-way catalyst. This is what I did. [Embodiment of the Invention] FIG. 1 is a configuration diagram showing an embodiment of the present invention. In the same figure, first, the configuration of the engine side will be explained. 1 is a piston, 2 is a cylinder, 3 is an intake valve,
4 is an exhaust valve, 5 is an exhaust pipe, 6 is a three-way catalytic converter, 7 is an intake pipe, and 8 is a throttle valve. A bench lily 9 and an air cleaner 10 are provided on the upstream side of the throttle valve 8. The fuel enters the main fuel passage 1 when the intake air taken in through the air cleaner 10 passes through the bench lily 9.
The air is drawn into the cylinder 2 through the throttle valve 8 and the intake pipe 7, where it is atomized and becomes a mixture with intake air. In this case, a main air bleed 13 is provided in the middle of the main fuel passage 12, and the float chamber 11
The fuel inside is atomized in advance by intake air from a main air bleed passage 14 provided upstream of the bench lily 9, and then atomized. On the other hand, an idle port 15 is provided on the downstream side of the throttle valve 8, and a slow air bleed passage 16 is provided on the upstream side of the bench lily 9, and the fuel in the main fuel passage 12 is drawn from the slow air bleed passage 16. Air is atomized in slow air bleed 17 and idle port 1
It is discharged from 5. As a result, the throttle valve 8
Fuel is secured during idling when the opening is almost fully closed. In this case, idle port 1
The amount of fuel discharged from the fuel pump 5 is adjusted by a slow adjust screw 18. Here, the throttle valve 8 is connected to an accelerator pedal (not shown), and its opening degree corresponds to the amount of depression of the accelerator pedal while driving, and when the throttle valve 8 is idling after releasing the accelerator pedal, it is necessary to maintain the idling state. The required opening is obtained. Further, the throttle valve 8 is provided with a lever 19 on its rotating shaft, and by driving this lever 19 with an actuator 20, which will be described later, the opening degree during idling can be varied. Next, to explain the configuration of the idle rotation speed control system, 20 is a DC motor 21 and a gear mechanism 22.
It is an actuator that converts the rotational movement of the DC motor 21 into linear movement of the plunger 23 in the gear mechanism 22, and uses this linear movement to drive the lever 19 to vary the opening degree of the throttle valve 8. 21 is supplied with a forward rotation control pulse U and a reverse rotation control pulse D having a predetermined pulse width from the control circuit 30. In this case, the actuator 20 is provided with an idle state detection switch 24 that is turned on (closed) when the tip of the plunger 23 is in contact with the lever 19, that is, when the accelerator pedal is released and the vehicle is idle. Also,
When the opening degree of the throttle valve 8 is greater than or equal to the opening degree θ (for example, 2 degrees), which is smaller than the idling time determined in relation to the allowable temperature of the three-way catalytic converter 6, it is turned on (closed).
The position detection switch of the plunger 23 (hereinafter referred to as
(abbreviated as MP/SW) 31 is provided. Next, 25 is a rotation speed detector that detects the engine rotation speed, and here, an ignition coil 26 and an interrupter 27
A rotation pulse signal with a period corresponding to the engine rotation speed N is extracted from the connection point with the engine rotation speed N. Reference numeral 28 indicates an operation start switch (hereinafter abbreviated as A/C SW) for the air conditioner, which is one of the engine loads, and 29 indicates that the transmission (not shown) is in the neutral position or the clutch (not shown). 30 is an idle switch 24 that detects an idle state, a rotation speed detector 25, an A/C/C.
The throttle valve opening during idling and deceleration is controlled based on the output signals of the SW 28, the speed change switch 29, and the position detection switch 31, and the engine speed converges to the target rotation speed _Np , and the air-fuel ratio is controlled during deceleration. This is the control circuit that does this. As shown in FIG. 2, the control circuit 30 includes an arithmetic processing unit (hereinafter abbreviated as CPU) 300 and a read-only memory (hereinafter abbreviated as ROM) that stores programs, constants, etc. for controlling the idle rotation speed. 301, and a random access memory (hereinafter abbreviated as RAM) 3 that stores results etc. during calculations.
02, the various switches and actuator 2 mentioned above
Interface circuit for transmitting and receiving signals with 0 (hereinafter referred to as
It consists of 303 (abbreviated as IFC). Next, the third section regarding the operation related to the above configuration is explained.
This will be explained using the flowchart shown in FIG. First, when the engine is started, the CPU 300
According to the program stored in 301, processing as shown in FIG. 3 is executed. In other words, CPU3
00 receives the output signal from the rotation detector 27 and measures the period of the signal to detect the current engine rotation speed N (step 100), and then calculates the target rotation speed _Np at idle (step 100). 10
1). The target rotational speed N _p during idling differs depending on whether the air conditioner is in an operating state or in a non-operating state, and is determined, for example, as shown in Table 1.

〔Effect of the invention〕

As explained above, in addition to the actuator that variably controls the throttle valve opening, the present invention includes a position detection means for detecting the drive position of the actuator, and when the actuator is idling, the engine rotation speed converges to the target rotation speed. During deceleration, the actuator is driven so that the throttle valve opening becomes an optimum opening, which is smaller than when idling, based on the detection output of the position detection means, which is determined in relation to the allowable temperature of the three-way catalyst. It is composed of Therefore, with an inexpensive configuration, it is possible to control the idle speed and prevent abnormal temperature rise of the three-way catalyst during deceleration, improving fuel efficiency and extending the service life of the three-way catalyst. effective.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a block diagram showing the detailed configuration of the control circuit.
Figure 4 and Figure 4 are flowcharts showing the operation details of the control circuit, Figure 5 is a graph showing an example of actuator drive time with respect to the deviation between the target rotation speed and the engine rotation speed, and Figure 6 is the operation of the air conditioner. FIG. 7 is a time chart showing an example of the control pulses generated at the start, and FIG. 7 is a flow chart showing the operation details during deceleration. 1... Piston, 2... Cylinder, 3... Intake valve, 6... Three-way catalytic converter, 7... Intake pipe,
8... Throttle valve, 9... Bench lily, 10...
...Air cleaner, 11...Float chamber, 19...
Lever, 20... Actuator, 21... DC motor, 22... Gear mechanism, 23... Plunger, 24... Idle switch, 25... Rotation speed detector, 28... A/C/SW, 29... Speed change switch, 31...Position detection switch, 30...Control circuit, 300...Arithmetic processing unit, 301...Read only memory, 302...Random access memory, 303...Interface circuit.

Claims (1)

[Claims] 1. A rotation speed detection means for detecting the rotation speed of an internal combustion engine having a catalytic converter in an exhaust passage, a target rotation speed setting means for setting an idle target rotation speed, and an actuator for variably controlling the throttle valve opening during idle. Position detection means for detecting the drive position of the actuator, and feedback for driving the actuator so that the engine speed at idle converges to the target rotation speed in response to the detection outputs of the rotation speed detection means and target rotation speed setting means. and a control means for driving the actuator based on the detection output of the position detection means so that the opening degree of the throttle valve becomes an optimum opening degree determined in relation to the permissible temperature of the catalytic converter when the engine is decelerated. An idle speed control device for an internal combustion engine, comprising a control means.