JPS5872670A - Fuel pump control device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To economize the wasteful consumption of electric power and improve the cost of fuel by intercepting the electric source circuit of a fuel pump at the time of fuel cutting. CONSTITUTION:A fuel-cut detector 6 outputs a fuel-cut signal S2 to give a high level for fuel supply and a low level for fuel-cut. Meanwhile, a control circuit 5 is composed of a switch circuit 7 to be on when the fuel-cut signal S2 is in the high level and off when in the low level, a switch circuit 3, and a series circuit of resistances R2 and R3. Consequently, when an engine is off, and when the engine is on but fuel is cut, a switch circuit 3 or 7 is off, and a transistor Q is off. Then, a fuel pump 4 is intercepted from its electric source circuit, and stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a fuel pump that supplies fuel to an internal combustion engine.

As a fuel pump for modern automobile internal combustion engines.

Pumps driven by electric power, such as electromagnetic pumps, are commonly used.

Therefore, a control device that supplies power to the fuel pump only when the engine requires fuel is required. FIG. 1 is an example of a conventional control device.

In Figure 1, the two-rotation detection device 1 detects that the engine is rotating based on, for example, the signal of the crank angle sensor or the neutral point voltage of the alternator, and the level is high when the engine is rotating once, and low when it is stopped. A rotation signal S1 is output.

Next, the control circuit 2 is constituted by a series circuit of a switch circuit 6 and a resistor R2°R3.

The switch circuit 6 is turned on when the one-rotation signal S1 is at a high level, and turned off when it is at a low level.

Therefore, when the engine is rotating, the switch circuit 5 is turned on, so the base potential of the transistor Q1 becomes high level, and the transistor Q1 is turned on.

Therefore, the fuel pump 4 is supplied with electric power from the power source Vaa, and the fuel pump 4 is operated.

However, in the conventional control device as described above.

When the engine is rotating, the fuel pump is always driven, so two engines are rotating.

Furthermore, the fuel pump is driven even when fuel is not required, that is, when fuel is cut (temporarily interrupting fuel injection) during deceleration.

If you drive the fuel pump during a fuel cut when no fuel is needed as described above, you will waste electricity.
There also arises the problem that the amount of fuel flowing back from the fuel pump to the fuel tank increases, causing a rise in fuel temperature.

The present invention has been made in order to solve the above-mentioned problems, and provides a fuel pump control device that saves electric power and eliminates the negative effects on fuel by eliminating unnecessary driving of the fuel pump. With the goal.

In order to achieve the above object, the present invention has the following features.

A means for detecting a fuel cut and a means for cutting off the power supply circuit of the fuel pump at the time of the fuel cut are provided, and the fuel pump is configured to be stopped at the time of the fuel cut.

The present invention will be described in detail below based on the drawings.

FIG. 2 is a diagram showing an embodiment of the present invention.

In FIG. 2, 6 is a fuel cut detection device which outputs a fuel cut signal S2 which is at a high level when fuel is supplied and is at a low level when fuel is cut.

Switch circuit 7 which is turned on when the level is low and turned off when the level is low; and the switch circuit 3 described above. It is composed of a series circuit of resistors R2 and R5.

Therefore, when the engine is not rotating, and even when the engine is rotating but during fuel cut, the switch circuit 5 or 7 is turned off, so the transistor Q1 is turned off.
The power supply circuit of the fuel pump 4 is cut off, and the fuel pump 4 is stopped.

In addition, in FIG. 2, the fuel cut detection device 6 is specially shown as one block, but it is a normal block.

In an engine equipped with a fuel cut function, it is determined that a fuel cut is to be performed when the operating variables of the engine are in a specific state (2), for example, when the engine speed is above a predetermined value and the throttle valve is fully closed, Since a signal for stopping fuel injection is sent out, that signal may be used as the fuel cut signal S2.

Also, as the control circuit 5, a switch circuit 5.7 and a resistor R
2. Although the series circuit of R5 is shown as an example, in an engine in which the amount of fuel injection, the amount of exhaust gas recirculation, etc. is centrally controlled using a microconbeater, the function of the control circuit 50 may also be performed by the microconbeater. I can do it.

FIG. 6 is a flowchart of calculations in the case where the control circuit 5 is composed of a five-micron repeater.

In the flowchart of FIG. 6, it is determined at P whether or not the engine is rotating, and at R2 it is determined whether or not the fuel is being cut. Pl is YES and R2 is N
In the case of O, that is, when the engine is rotating and the fuel is not being cut, go to R5, turn on the power, and operate the fuel pump.

On the other hand, if Pl is No or even if Pl is YES, R2
If is YES, that is, if the engine is stopped or the fuel is being cut while the engine is rotating, the process goes to R4 to turn off the power and stop the fuel pump.

Furthermore, when the fuel cut is canceled and fuel injection is restarted, the fuel pump will start operating immediately.

Further, since there is residual pressure, there is no risk of adversely affecting the responsiveness of fuel injection when the fuel cut is canceled.

As explained above (according to the present invention), since the power supply circuit of the fuel pump is configured to be cut off when fuel is cut, unnecessary power consumption can be saved, and therefore fuel efficiency can be improved.

Further, it is possible to prevent adverse effects such as a rise in fuel temperature due to an increase in the amount of recirculation from the fuel pump to the fuel tank.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an example of a conventional control device, FIG. 2 is a diagram of an embodiment of the present invention, and FIG. 6 is a diagram of an embodiment of a flowchart showing calculations of the present invention. Explanation of symbols 1...Rotation detection device 2...Control circuit 3...
Switch circuit 4...Fuel pump 5...Control circuit 6...Fuel cut detection device 7...Switch circuit agent patent attorney Junnosuke Nakamura 1 diagram O 3v4 4

Claims (1)

[Claims] In an internal combustion engine that receives fuel from a fuel pump operated by electric power, the fuel pump is stopped when the fuel is cut, and the engine is provided with a means for detecting a fuel cut and a means for cutting off the power supply circuit of the fuel pump when the fuel is cut. A fuel pump control device for an internal combustion engine, characterized by: