JPS6149158A - Fuel cut control device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent an engine causing an engine stop by a rapid decrease of a speed due to clutch disconnection or the like when the engine is decelerated, by cutting off fuel when a throttle valve is fully closed with the speed in a predetermined value or more for a fuel cut at deceleration time an restarting supply of the fuel when a decelerative change rate of the speed is in a predetermined value or more. CONSTITUTION:A mixture from a carburetor 1 supplying fuel to an internal- combustion engine 4 is supplied to the engine in accordance with the opening of a throttle valve 14. When the throttle valve opening 15 is fully closed or almost fully closed and when the engine is decelerated at a speed in a predetermined value or more, a control device 9, outputting a fuel cut signal and closing a solenoid operated valve 8 arranged in a fuel passage 7 to a fuel nozzle 2 in the carburetor 1, cuts off fuel. During such deceleration, if a clutch is disconnected and/or a speed shift is placed in a neutral position, the engine, whose speed rapidly decreases, causes an engine stop, but the control device 9, if it detects a change rate of the decrease of this speed being in a predetermined value or more, restarts supply of the fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel cut control device for an internal combustion engine using a carburetor.

2. Description of the Related Art Conventionally, fuel supply to an internal combustion engine has been cut when predetermined conditions are met in terms of fuel efficiency and exhaust gas.

Generally, the following two conditions are basically adopted for cutting fuel.

■The engine speed must be higher than the specified speed.■The throttle valve must be fully closed or almost fully closed.However, in the case of a carburetor internal combustion engine, once the fuel is cut, the engine speed must be at least the specified speed. Even if the fuel supply is restarted from this state, the engine will not have enough fuel due to the long route and the need for a constant amount of fuel to adhere to the pipe walls of the route. It will take a relatively long time until fuel is supplied. For this reason, unlike an electronic fuel injection internal MA engine that can supply sufficient fuel immediately after recovery, the following problems occur if only the above conditions are met. That is, as shown in FIG.
When the throttle valve is fully closed when the engine speed NE is higher than the predetermined speed NEA, the conditions ① and ③ above are met, fuel is drained, and coasting is performed with the engine brake applied. If the clutch is disengaged or the engine is placed in neutral during this coasting, the engine speed will rapidly drop due to no load. For this reason, when it is detected that the engine speed has fallen below the predetermined speed NE/ and the fuel supply is resumed, the deceleration of the engine speed is large and, as mentioned above, there is not enough fuel being supplied to the engine. Since it takes a relatively long time to reach the internal combustion engine, there is a problem in that the engine stops rotating before sufficient fuel is supplied to the internal combustion engine.

Therefore, in the past, a clutch switch that detects whether the clutch is engaged or not, and a neutral switch that detects whether the shift is in the neutral state are provided, and if the clutch is disengaged or in the neutral state, the fuel is cut off. Countermeasures have been taken to ensure that this does not occur, and that if the clutch is disengaged during coasting, the fuel supply is immediately restarted to prevent the engine from stopping. However, this method requires a clutch switch and a neutral switch, which has the disadvantage of increasing costs.

Problems to be Solved by the Invention The present invention improves these conventional problems, and its purpose is to stop the engine after returning from a fuel cut state without using a clutch switch or neutral switch. The purpose is to prevent it.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has an objective of solving the above-mentioned problems. In a fuel cut control device for an internal combustion engine that cuts the supply of fuel using a solenoid valve installed in a fuel pipe that supplies fuel to a nozzle that injects fuel, the rate of change in deceleration of engine speed is greater than a predetermined value. A means for detecting the change rate is provided, and when the rate of change becomes larger than a predetermined value, the means stops the fuel cut by the electromagnetic valve and restarts the fuel supply.

If the clutch is disengaged or the engine enters the neutral state during coasting after the operating fuel is cut, the engine speed will drop rapidly, and the rate of change in the engine speed (rotational speed difference/deceleration per unit time) will suddenly change. Since this becomes larger than the predetermined value, fuel supply is immediately restarted.

Embodiment FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention, where 1 is a venturi and 2 is a nozzle. Fuel is injected into the venturi 1 from the nozzle 2 by the force of negative pressure inside the venturi 1, and it is mixed with air. The mixed fuel is introduced into the internal combustion engine 4 via the intake manifold 3. 5 is a fuel tank, from which fuel is sent to a gasoline chamber 6 and supplied to the nozzle 2 through a fuel pipe 7. A solenoid valve 8 is provided in the middle of the fuel pipe 7. This solenoid valve 8 operates in two modes: ON and OFF, which shuts off the pipe passage of the fuel pipe when the control signal d becomes high level and is energized from the power source B, and opens the pipe passage when the energization is removed. This is a type of solenoid valve that 9 is a controller, which is a microprocessor (
MPU) 10 and memory 11 connected to it. It consists of an output ink face 12 and an input ink face 13. The memory 11 stores the programs shown in FIG.
It has an OM section and a RAM section used for calculations and the like. The input ink face 13 receives a throttle fully closed signal a from a throttle switch 15 that detects that the throttle valve 14 is fully closed or approximately fully closed, and an engine speed signal from a crank angle sensor, for example, related to MA+JSl. b. Take in the vehicle speed signal C from the vehicle speed sensor 16 and send it to the input port of MPU10. The output ink face 12 is MP
It is an ink face between Ul0 and solenoid valve 8, and solenoid valve 8
A control signal d is sent to.

FIG. 2 is a flowchart showing an example of fuel cut control performed by MPU10, and this process is executed, for example, at every predetermined period. The MPU10 first calculates the engine speed NE based on the engine speed signal C, and calculates the vehicle speed sp based on the vehicle speed signal C. Next, the current engine speed Nu(i)
The current deceleration DLNE (i') is determined by subtracting the previous engine speed NE (i-1) from the current deceleration DLNE (i').

Then, it is determined whether the following five conditions are satisfied.

1) Is the engine speed NE greater than or equal to the predetermined speed NEI?

2) Is the current deceleration DLNE (i) less than a predetermined deceleration, for example, 11000 rp/s?

3) Is the current deceleration DLNE (i) less than or equal to the previous deceleration DLNE (i-1) multiplied by 3/2?

That is, is the rate of change in deceleration less than or equal to a predetermined value?

4) Is the throttle valve fully closed or almost fully closed?

5) Is the table speed less than a predetermined value, for example 10 km/h?

When all of the above five conditions are met, the MPU10 turns on the solenoid valve 8 using the control signal d to cut fuel, and when any one of the conditions is not satisfied, the solenoid valve 8 is turned on.
Turn off and restart fuel supply.

FIG. 3 is an explanatory diagram of the operation of this embodiment. When the throttle valve 14 is fully closed when the vehicle speed is above a predetermined value and the engine speed NE is above the predetermined speed NEβ, the engine speed NE gradually decreases, and conditions 2) and 3) above are also satisfied. Fuel will be cut off at this point. If the clutch is disengaged or placed in neutral during coasting, the engine speed will drop rapidly. Then, the rate of change in deceleration exceeds the predetermined value β1, condition 3) is no longer satisfied, and fuel supply is immediately restarted.

Also, the rate of change in the deceleration of the engine speed reaches its maximum immediately after the clutch is disengaged, and then the engine speed decreases at a constant deceleration (large deceleration because the clutch is disengaged), so the rate of change is It becomes smaller than 1 again at a predetermined value. However, at that time, the deceleration is equal to or higher than the predetermined value of 12, so the inconvenience of instantaneous fuel cut after restarting fuel supply is eliminated. Of course, even if the configuration does not adopt the condition 2) above, it is possible to prevent the rotation of the engine from stopping to some extent since the fuel supply has been restarted once. Another countermeasure is to forcibly prohibit fuel cut for a predetermined period of time (the time required for the engine speed to drop below a predetermined value NIEβ) when the condition 3) above is no longer satisfied. Also good.

In the above embodiment, the fuel cut condition is 1).

In addition to 3) and 4), 2. ), 5) were adopted, but
It is also possible to omit this or to adopt another condition. In addition, the fuel cut should be performed when conditions 1) and 4) are met, and the fuel cut should be restarted when any of the conditions 1), 3), and 4) (including 2) are not met if necessary. You can also do it.

As described in detail, according to the present invention, if the clutch is disengaged or the engine is placed in the neutral state while coasting with the fuel cut and the engine brake applied, the engine rotation will be reduced. Since sudden changes in the rate of change in deceleration are detected immediately and fuel supply is restarted, it takes a relatively long time to recover from the fuel cut state and supply sufficient fuel to the engine. Even in the case of a carburetor type internal combustion engine, there is an effect that the rotation of the engine can be prevented from stopping after the fuel supply is restored without using a clutch switch or a neutral switch.

3 is a flowchart showing an example of fuel cut control performed by MPU10, FIG. 3 is an explanatory diagram of the operation of the present invention, and FIG. 4 is an explanatory diagram of conventional problems.

1 is a venturi, 2 is a nozzle, 3 is an intake manifold, 4 is an internal combustion engine, 7 is a fuel vibe, 8 is a solenoid valve, 9
is the controller.

Claims (1)

[Claims] When the throttle valve is fully closed or nearly fully closed and the engine speed is higher than a predetermined speed, the solenoid valve installed in the fuel pipe that supplies fuel to the nozzle that injects fuel into the venturi injects fuel. In a fuel cut control device for an internal combustion engine that cuts supply, means is provided for detecting that a rate of change in deceleration of engine speed has become larger than a predetermined value, and the means detects when the rate of change is greater than a predetermined value. 1. A fuel cut control device for an internal combustion engine, characterized in that when the fuel temperature increases, the fuel cut by the electromagnetic valve is stopped and the fuel supply is restarted.