JPS6287640A - Engine decelerating fuel cut-off device - Google Patents

Abstract

PURPOSE:To make it possible to enhance the economy of fuel consumption without a passengr feeling a large shock upon recovery of fuel, by providing such an arrangement that larger the rate of lowering of rotational speed of an engine, the lower the rotational speed of the engine is set for recovery of fuel. CONSTITUTION:A control unit 7 calculates a deceleration which is the rate of lowering of rotational speed of an engine per unit time, in accordance with the rotational speed of the engine which is detected by a rotational speed sensor 8. Further, the decelerating condition of the engine is determined when the rotational speed of the engine exceeds a rotational speed upon fuel recovery which is set in accordance with a deceleration of the engine and an idle switch 9 detects an idle opening degree of a throttle valve 5, and therefore, fuel injection from a fuel injection valve 6 is cut off. In view of the fact that, if the lowering rate of rotational speed of the engine is large, a passenger is hard to feed a shock upon fuel recovery, the larger the deceleration of the engine, the linearly lower the rotational speed of the engine upon fuel recovery is set.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine deceleration fuel cut device that cuts fuel supply during deceleration.

(Prior Art) In automobile engines, it is known that fuel is cut during deceleration in order to improve exhaust purification performance and fuel efficiency during deceleration.

In such engines, to prevent stalling,
The fuel return rotation speed at which the fuel supply is restarted is determined in advance, and this fuel return rotation speed is required to be low from the point of view of fuel efficiency, but it also reduces the return shock (
A high torque shock is required.

Therefore, we focused on the shift position of the transmission and set the fuel return rotation speed low at the shift position where the return shock is small.

It is conceivable to increase the fuel return rotation speed at a shift position where the return shock is large.

As an example, Japanese Patent Application Laid-Open No. 55-160141 discloses that when the transmission is in the low speed position, the driving torque is large, so the torque fluctuation when fuel cut and its release is large, which affects the occupants. Because the shock will be greater,
It has been proposed to increase the fuel return rotational speed when in a low speed position.

However, the inventor has conducted extensive research and found that although it may be said that the larger the driving torque is, the larger the torque fluctuation is, it cannot be said that the return shock experienced by the occupant due to fuel return is greater. In other words, when decelerating, the occupant receives a deceleration shock due to deceleration, and if a return shock of the same degree acts, the greater the deceleration shock, the smaller the return shock felt by the occupant. It can be said that the greater the rate at which the engine speed decreases per hour (deceleration), the greater the deceleration shock, and conversely, the less the occupant feels the return shock. For example, in Fig. 4, deceleration state B has a larger deceleration than deceleration state A, and it is thought that the occupant feels the deceleration shock more strongly in deceleration state B. The rotation speed can be set low.

(Objective of the Invention) An object of the present invention is to provide a deceleration fuel cut device that can improve fuel efficiency in an engine that cuts fuel during deceleration without causing the occupant to feel much of a return shock.

(Structure of the Invention) In order to achieve the L2 objective, the present invention detects the reduction rate of the engine rotation speed by receiving the output of the rotation speed detection means for detecting the engine rotation speed by the deceleration detection means, and detects the rate of decrease in the engine rotation speed. Accordingly, a return rotation speed setting means is provided which sets the fuel return rotation speed lower as the rate of decrease in the engine rotation speed increases.

(Embodiment) Hereinafter, an embodiment of the present invention will be explained with reference to the drawings. In FIG.
is connected. In the intake passage 2, an air cleaner (not shown) and an air flow meter (
AFM) 4, a throttle valve 5, and a fuel injection valve 6 are arranged in this order.

7 is a control unit, which includes an air flow meter 4 for detecting the amount of intake air. It is electrically connected to a rotation speed sensor 8 that detects the engine rotation speed and an idle switch 9 (Idl sw) that is connected to the throttle valve 5 and detects the idle opening, and an ignition pulse is input to the fuel injection valve 6. It outputs a predetermined injection pulse.

Next, the configuration of the control unit 7 will be explained together with its operation.

A basic injection amount is set in the basic injection amount setting circuit 21 based on the intake air amount signal from the air flow meter 4 and the engine rotation speed signal from the rotation speed sensor 8, and the corresponding injection pulse is set as the ignition pulse. The pulse generation circuit 22 generates the first pulse in synchronization with the
The fuel injection valve 6 is controlled via the ND circuit 23 and the injection valve drive circuit 24.

Further, the engine speed detected by the speed sensor 8 is differentiated by a differentiation circuit 25 to calculate the deceleration, which is the rate of decrease in the engine speed per unit time. Since it is difficult to feel a shock, the function circuit 26 converts so that the larger the deceleration, the smaller the output corresponding to the fuel return rotation speed linearly becomes (see FIG. 3).

The current engine rotation speed detected by the rotation speed sensor 8 is compared with the output of the function circuit 26 in the comparison circuit 27, and if it is larger than the above output, that is, the fuel return rotation speed, the current engine rotation speed is output to the second AND circuit 28. An ON signal is output.

On the other hand, when the idle switch 9 detects that the throttle valve 5 is at the idle opening in the idle state, the second A
An ON signal is output to the ND circuit 28.

Therefore, when the engine speed is equal to or higher than the fuel return speed set corresponding to deceleration and the throttle valve 5 is at the idle opening, it is determined that the engine is in a deceleration state, and the second AND circuit 28 outputs an ON signal. output, it is inverted and the Lth
It is input to the AND circuit 23. As a result, the first AN
Since no ON signal is output from the D circuit 23, the injection valve drive circuit 24 does not operate in the above deceleration state, and fuel injection is canted.

(Effects of the Invention) The present invention, as described in IS, lowers the fuel return rotation speed because it is difficult for the occupants to feel the return shock when the rate of decrease in the engine rotation speed is large, so that the occupant does not feel the return shock. It is possible to improve fuel efficiency without feeling too much.

[Brief explanation of drawings]

Fig. 1 and Fig. 2 show an embodiment of the present invention, Fig. 1 is an overall configuration diagram of an engine deceleration fuel cut device, Fig. 2 is a block diagram of a control unit, and Fig. 3 is a deceleration and function circuit. A diagram showing the relationship with the output voltage (fuel return rotation speed), and FIG. 4 is a diagram showing a state of change in the engine rotation speed during deceleration. 1...Engine body, 2...Intake passage, 7...Control unit, 8...
・Rotation speed sensor, 9...Idle switch, 2
5...Differential circuit, 26...Function circuit.

Claims (1)

[Claims] (1) In an engine having a deceleration time detection means for detecting deceleration time, and a fuel cut means for receiving the output of the deceleration time detection means and cutting the fuel supply during deceleration, a rotation speed detection means for detecting the engine speed. and a deceleration detecting means that receives the output of the rotational speed detection means and detects a rate of decrease in the engine rotational speed, and receives the output of the deceleration detection means and lowers the fuel return rotational speed as the rate of decrease in the engine rotational speed increases. 1. A deceleration fuel cut device for an engine, comprising a return rotation speed setting means for setting a return rotation speed.