JPS61149558A - Control method for speed reduction of engine - Google Patents

Abstract

PURPOSE:To prevent an air-fuel ratio from rapidly varying upon starting to control speed reduction of an engine so as to sharply moderate any car shock by driving an auxiliary fuel pump a prescribed member of times set previously upon starting the speed reduction control while cutting fuel. CONSTITUTION:Provided engine rpm exceeds, in engine operation, prescribed rpm which requires speed reduction control, while a neutral state detection switch 51 is switched on and a clutch stays in a connected state, speed reduction conditions hold, whereby a solenoid valve 22 is switched off by means of ECU59 to cut fuel supply. Thereupon, an auxiliary fuel pump 35 is driven a prescribed number of times, and thus the fuel sucked into a cylinder chamber 42 from a float chamber 40 is injected from an auxiliary nozzle 43 into an air intake path 3 located upwardly of the large venturi 44 of a carburetor 2. Hereby, any car shock caused upon starting speed reduction control is moderated while fuel consumption is improved together with prevention of abnormal discharge of HC.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine deceleration control method using an auxiliary fuel pump during deceleration control by cutting fuel.

(Prior Art) Conventionally, as described in, for example, Japanese Patent Laid-Open No. 56-107940, fuel is cut or restricted during deceleration to prevent abnormal HC emissions while improving fuel efficiency. However, in this case, when the fuel is cut off at the start of deceleration, the air-fuel ratio changes rapidly, resulting in severe car shock.As a means to alleviate this car shock, for example, Japanese Utility Model Application No. 58-195045 discloses As described in , a leakage type solenoid valve is used for the fuel cut solenoid valve to prevent the air-fuel ratio from changing rapidly.
In this case, following the deceleration control method, leaked fuel is supplied to the engine, which not only deteriorates fuel efficiency but also deteriorates the exhaust gas purification characteristics and makes engine braking less effective.

(Problems to be Solved by the Invention) In deceleration control with fuel cut, the present invention prevents wasteful fuel consumption, etc., and prevents rapid changes in the air-fuel ratio immediately after the start of deceleration control. The purpose is to significantly alleviate car shock immediately after control starts.

(Means for Solving the Problem) As shown in FIG. 1, the present invention determines whether or not a deceleration condition is satisfied, such as by returning the accelerator pedal while the engine speed is high enough to require deceleration control in step S01. If the deceleration condition is satisfied, the fuel passage in the carburetor is immediately shut off at step 802, and at step 803
In this method, the auxiliary fuel pump is driven a predetermined number of times in order to prevent sudden changes in the air-fuel ratio.

(Embodiment) Next, the configuration of an embodiment of the present invention will be described with reference to FIGS. 2 to 5.

A throttle valve 4 that opens in response to the amount of depression of the accelerator pedal is attached to an intake passage 3 that supplies fuel from the carburetor 2 to the engine, and is biased in the direction of closing the pulp by a spring (not shown). The valve closed position is determined by the actuator 7, in which the throttle lever 6 fixed to the shaft 5 of the throttle valve 4 rotates the threaded rod 10 in the forward and reverse directions via the C motor 8 and the gear train 9, which enables reversible operation. The circumferential movement of the output shaft 11, which is fitted with a threaded rod 10 and screwed together, is determined by contact with the touch head 12 at the tip of the actuator that moves back and forth, and the contact of the throttle lever 6 with the touch head 12 is determined by this contact. The end of the stroke of the output shaft 11 is detected by turning on the idle switch 15 when the final gear 14 and the output shaft 11 move slightly backward against the biasing force of the spring 13. It is detected by contacting the lever 18 of 17.

This carburetor 2 includes a main cut electromagnetic valve 22 for cutting off the fuel supply to the main nozzle 20 formed in the small bench lily 19 of the intake passage 3 at the main jet 21 position, and a main cut solenoid valve 22 formed near the throttle valve 4 of the intake passage 3. A slow-cut solenoid valve 24 for cutting the fuel supply to the slow boat 23 that has been operated, and an air bleed control valve 25 for adjusting bleed air to the main and slow systems, in this case a nut body 27 via a stepper motor 26. By moving the needle valve 29 back and forth together with the threaded rod 28 whose movement in the circumferential direction is regulated by rotating it in the forward and reverse directions, the air passages 31 and 32 are passed from the air hole 30 to the main system and the slow fuel passage 33. .34, and an auxiliary fuel pump 35 driven by an electromagnetic solenoid that increases the amount of fuel supplied to the engine during engine startup and acceleration, in this case a solenoid coil 36.
The reciprocating movement of the piston 39 via the plunger 38 due to the on/off operation of the switch and the biasing force of the spring 37 allows the fuel from the float chamber 40 of the carburetor 2 to pass through the suction side check valve 41 and to the -H cylinder chamber 42. An auxiliary fuel pump 35 is installed to supply the fuel from the discharge side check pulp 43 to the intake passage 3 through an auxiliary nozzle 45 formed above the large venturi 44.

In the carburetor 2 formed in this way, the DC motor 8 of the actuator 7, each switch 15, 17, each fuel cut solenoid valve 22, 24, the stepper motor 26 of the air bleed control pulp 25, and the auxiliary fuel A solenoid coil 36 of the pump 35, a throttle opening sensor 46 that is attached to the carburetor 2 and generates an output corresponding to the opening of the throttle valve 4, a water temperature sensor 47 that is attached to the water jacket of the engine, and an ignition coil. a vehicle speed sensor 49 that generates an output corresponding to the speed of the vehicle; an 02 sensor 50 that is attached to the exhaust passage and generates an output corresponding to the oxygen concentration; A clutch/neutral detection sensor 51 that changes the output when the side lamp is on, a side lamp detection sensor 52 that generates an output when the side lamp is on, an economy/diagnosis lamp 53 that lights up during economy and diagnosis, an air conditioner switch 54, and a starter switch 55. , ignition key switch 56 , and alternator control recess 5
7 are connected to an electric control circuit 59 for engine control, commonly known as an ECU, in which power supply from a battery 58 is controlled on and off by an ignition key switch 56.

Next, FIG. 3 shows a specific example of the electric control circuit 59, in which the microcomputer CPU, which is controlled according to the program in the storage circuit ROM, receives the engine rotational speed from the engine rotational speed sensor 48 via the waveform shaper 60. In addition to inputting a pulse signal with a frequency corresponding to the frequency, an analog signal corresponding to the engine cooling water temperature from the water temperature sensor 47, an analog signal corresponding to the opening of the throttle valve 4 from the throttle opening sensor 46, and an O2 sensor The analog signals corresponding to the oxygen concentration from 50 are inputted via the input port 2 after being converted into digital signals via the A/D converter 61, and are input to the idle switch 1.
5, clutch/neutral detection switch 51, air conditioner switch 54, pulse output vehicle speed sensor 49, ignition key switch 56, and starter switch 55. The output port 4 of the computer CPU is connected to the DC motor 8 of the actuator 7, the solenoid coil 36 of the auxiliary fuel pump 35, the main cut solenoid valve 22, the slow cut solenoid valve 24, and the alternator control circuit via drive circuits 65 to 69. 57 are output, as well as output port door 0 and drive circuit 7.
A stepper motor 26 of an air bleed control pulp 25 is connected via 1.

Next, the operation of this embodiment will be explained.

In an engine control device configured in this way, in particular an engine control device for an electronically controlled chokeless carburetor, the microcomputer CPU has a target idle opening and a target idle rotation that change depending on the engine cooling water temperature. During idling operation after warm-up, the engine is idle-controlled to the target idle speed with the throttle valve 4 set to the target idle opening, and the microcomputer CPU The data required to determine whether the deceleration control conditions are met by cutting fuel is a relatively high engine speed NE1 that requires preset deceleration control.
and a relatively low engine rotational speed NE2 that does not require deceleration control or cancels deceleration control, and the engine is controlled according to the flowchart in FIG. 4 during deceleration in this setting state.

That is, in step 101, it is determined whether or not the deceleration control conditions due to fuel cut are satisfied, for example, the engine speed is NE1 or higher that requires deceleration control, the neutral state detection switch 51 is on, and the engine drive system is not transmitting power. As shown in FIG. 5, in step 102 when the deceleration control condition is satisfied
The solenoid valve 22 is turned off, and the fuel passage 33 of the carburetor 2 is turned off.
34, and it is determined in step 103 whether or not a fuel cut flag is set. Since the flag is not set in this first control cycle, the flag is set in step 104, and in step 105 After setting the count number of the driving number setting counter of the auxiliary fuel pump 35 to N=2, for example, the auxiliary fuel pump 35 is driven in step 106, and the flag is set in step 103 in the next control cycle. In step 107, it is determined whether the count number is N-0, and if it is not 0, step 108
After setting the count number N to a value smaller by 1 (N-1), the auxiliary fuel pump 35 is driven in step 106. In this way, the auxiliary fuel pump 35 is driven in every control cycle, and the dotted line in FIG. Compared to the conventional system, as shown by the solid line, sudden changes in the air-fuel ratio are prevented, car shock at the start of deceleration control is greatly alleviated, and the number of counts is reduced to N.
In the control cycle after -0, step 107
When it is determined that (N=O), the auxiliary fuel pump 35 is not driven and the engine continues to decelerate in a fuel cut state to prevent abnormal HC discharge and to effectively exert engine braking. The control continues, and during this fuel cut deceleration control, it is determined in step 101 that, for example, the engine speed becomes below NE2, which does not require deceleration control, or the engine speed reaches NE2, which does not require deceleration control.
2 or more, if it is determined that the deceleration control condition is not satisfied, such as whether the neutral state detection switch 51 is turned off or the engine drive system is in a power non-transmission state, the solenoid valve 22 is turned on in step 109 to restore the fuel. In the state,
At step 110, the fuel cut flag is reset and the engine deceleration control ends.

(Effects of the Invention) The present invention prevents rapid fluctuations in the air-fuel ratio at the start of deceleration control by driving the auxiliary fuel pump a preset number of times at the start of deceleration control after cutting fuel.
This has the effect of improving fuel efficiency and preventing abnormal HC emissions while greatly alleviating car shock at the start of deceleration control.

[Brief explanation of the drawing]

Fig. 1 is a flowchart clearly showing the system of the present invention, the second factor is an explanatory diagram of an embodiment of the invention, Fig. 3 is its electric circuit, Fig. 4 is its flowchart, and Fig. 5 is its FIG. 801-803...step

Claims (1)

[Claims] When deceleration conditions are met, such as when the accelerator pedal is released while the engine speed is high and requires deceleration control, the fuel passage in the carburetor is immediately shut off and the auxiliary fuel pump is activated to prevent sudden changes in the air-fuel ratio. A method for controlling deceleration of an engine, characterized in that the engine is driven a predetermined number of times.