JPS6048622B2 - Engine fuel cut control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for appropriately cutting the fuel supply to the engine in a system for supplying fuel to the engine.

In the conventional fuel cut system, when the engine is decelerated, when the engine speed is 2100 p, m or more, the negative pressure of the port at the slot position communicating with the engine is -400 mmHg or more, that is, -400 rT1 m.
When the vacuum becomes lower than Hg, after a delay of approximately 1,000 g, a solenoid valve located within the carburetor is activated to cut off the fuel supply to the engine.

The reason why such a delay mechanism is provided is that the durability of the above-mentioned solenoid valve is an issue, so the fuel cut system is not activated during shifts or slight decelerations, and the number of times the solenoid valve is activated is to prevent the fuel cut system from operating. The purpose is to minimize this. However, in this conventional fuel cut system, the rotation speed is such that afterburn occurs.

While the engine speed is decelerating from a high speed rotation of 3,500 p, m, or higher, there is a drawback that afterburn occurs continuously due to the remaining fuel during the above delay time. The present invention solves the above-mentioned problems, and an embodiment thereof will be described with reference to the accompanying drawings.
00, a rotation signal applied when p, m or more,
The negative pressure of the port at the slot position is -400m
When the engine speed exceeds mHg, the negative pressure signal c applied by a vacuum switch etc.
At the set rotation speed of 3500, p.

This is a rotation signal that is applied when the rotation speed is greater than or equal to m. G is an AND gate, which inputs the rotation signal a and the negative pressure signal via the delay mechanism D, and outputs the cut signal Cl when they match. G2 is also an AND gate, and this gate receives the negative pressure signal as well as the rotation signal C.
Input J respectively, and if these match, cut signal C2
Output. G3 is an OR gate, which inputs the cut signals Cl and Co, respectively, and outputs the fuel cut signal f.
Output c. FIG. 2 shows a club explaining the operation of FIG. 1, with the horizontal axis showing the rotation speed R and the vertical axis showing the fuel cut delay time T.

In the present invention as described above, as shown in FIG. 2, under the condition that the negative pressure is -400n1mH above λ, the engine is rotated at the first set rotational speed Ra), that is, 2100r. p. m
．． If this is the case, a cut signal C with a time delay of approximately 1 to 2 seconds is output via the delay mechanism D and gate G, and a fuel cut signal Fc is output via the gate G. Output, the solenoid valve in the carburetor is approximately 1
It is activated with a time delay of ~2 seconds and cuts the fuel supply to the engine.

Under the above negative pressure condition, the engine reaches the second set rotation speed Rc)
That is, 3500r. p. m. If it is higher than that, go to Gate G.

,G. The fuel cut signal Fc without time delay
is output, the solenoid valve in the carburetor is activated immediately without any time delay, and the fuel supply to the engine is cut off. In the present invention as described above, when the engine is between a first set rotation speed and a second set rotation speed larger than the first set rotation speed during engine rotation deceleration, a desired time delay is applied. With this, the fuel supply to the engine is cut, and the engine is running at or above a second set rotation speed that is between the first set rotation speed and a second set rotation speed that is larger than the first set rotation speed. This is a fuel cut control device for an engine, which is characterized in that the fuel supply to the engine is immediately cut off in response to the above-mentioned delay.
Afterburn occurs When the engine rotates at high speed, that is, when the rotation speed is higher than the second set rotation speed, even if the engine is decelerated, there is a time delay and the fuel supply is immediately cut, causing afterburn. This makes it possible to prevent afterburn, which occurs continuously during the fuel supply cut delay time during deceleration, unlike in the conventional example.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a graph explaining the same.

Claims (1)

[Claims] 1. In an engine fuel cut control device that cuts the fuel supply when the intake pipe negative pressure is equal to or higher than a set value and the engine speed is equal to or higher than a first set speed, the engine speed is set at the first set speed or higher. When the engine speed is between the engine speed and a second set speed that is larger than the first set speed, the fuel supply is cut even after a predetermined time delay, and when the engine speed is equal to or higher than the second set speed. The fuel cut control device for an engine is characterized in that the fuel supply is immediately cut off in response to the time delay.