JPS6039463Y2 - Electronic fuel injection amount control device - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement of an electronic fuel injection amount control device for a diesel engine. Specifically, the invention is concerned with the improvement of an electronic fuel injection amount control device for a diesel engine. The present invention relates to an electronic fuel injection amount control device.

Conventional electronic fuel injection amount control devices for electronically controlling the fuel injection amount of diesel engines detect the rotation speed of the diesel engine as an electrical signal, and use this electrical signal as one of the input signals to control the injection amount. The fuel injection amount is input to the calculation means, and the output of the injection amount calculation means is used to operate the injection amount control means to control the fuel injection amount so that the operating state of the diesel engine is optimized.

However, if the injection amount calculation means etc. malfunctions for some reason and the fuel injection amount remains increased, there is a risk that the engine will overrun and be damaged. If the circuit that detects this as an electrical signal breaks down and the electrical signal is not output even though the engine is rotating (rotary pickup disconnection, demagnetization movement), the actual engine Regardless of the rotation, the injection amount calculation means outputs a signal that increases the fuel injection amount, causing the engine to overrun.

Therefore, the purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional device, prevent the engine from overrunning even if the fuel injection amount increases due to failure of the injection amount calculation means, etc., and prevent the engine from overrunning. An object of the present invention is to provide an electronic fuel injection amount control device that does not cause an engine to overrun even when demagnetized.

To achieve this objective, the present invention provides at least a calculation means for inputting the rotational speed of the diesel engine as an electrical signal and calculating the optimum fuel injection amount to the diesel engine based on the electric signal, and In an electronic fuel injection amount control device comprising an injection amount control means for adjusting an amount of fuel injected into a diesel engine, the number of revolutions of the diesel engine is equal to or less than a first reference number of revolutions which is equal to or less than a predetermined number of revolutions based on the electric signal. low rotation signal detection means for detecting that the
a high rotation signal detection means for detecting, based on the electric signal, that the rotation speed of the diesel engine has reached a second reference rotation speed that is higher than the maximum rotation speed set by the calculation output stage; and the low rotation signal detection means. The present invention is characterized in that it includes a switch means which is activated by the detection output of the high revolution signal detection means and makes the input signal of the injection amount control means a signal at which the fuel injection amount becomes zero.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 is a block diagram showing the configuration of an electronic fuel injection amount control device to which the present invention is applied.

Reference numeral 1 indicates a rotation detection circuit, which detects the rotation speed of a member related to the rotation of the diesel engine as an electrical signal using a known electromagnetic pickup or the like, and converts it into a DC signal proportional to the rotation speed of the diesel engine using a conversion circuit 2. It is converted into voltage VN.

This DC voltage VN is applied to the fuel injection amount calculation circuit 3,
The optimal fuel injection amount to the diesel engine at any given time is calculated based on the DC voltage VN, and is output as a target injection amount signal SQ.

The target injection amount signal SQ is power amplified by an amplifier circuit 6, and then applied to an actuator of an injection amount control means 8 that adjusts the fuel injection amount to the diesel engine via a switch circuit 7, which will be described later. Positioning is performed according to the magnitude of the target injection amount signal SQ.

Therefore, an injection amount adjusting member such as a control rack of a fuel injection pump connected to the actuator assumes a position according to the magnitude of the target injection amount signal SQ,
Fuel injection amount is optimally controlled.

The above is the same as the conventional electronic fuel injection amount control device except for the switch circuit 7.

The DC voltage VN is also applied to the low rotation signal detection circuit 4 and the high rotation signal detection circuit 5.

The low rotation signal detection circuit 4 is a circuit that detects when the engine rotation speed has become a predetermined first reference rotation speed (for example, 100100 rpm or less) that is lower than the cranking rotation speed at the time of engine startup. Using the DC voltage VN
and a first reference voltage VL corresponding to the first reference rotation speed, and when the voltage IEVN becomes smaller than the voltage VL,
For example, it can be configured to provide a high level output voltage.

On the other hand, the high rotation signal detection circuit 5 detects that the engine rotation speed has reached a predetermined second reference rotation speed (for example, maximum rotation speed + 20 rpm) that is higher than the maximum rotation speed set by the fuel injection amount calculation circuit 3. A detection circuit that compares the DC voltage VN and a second reference voltage VH corresponding to the second reference rotation speed using, for example, a known comparator similarly to the low rotation signal detection circuit 4, When the voltage VN becomes larger than the voltage VH, it can be configured such that, for example, the output voltage is at a high level.

The output of the low rotation signal detection circuit 4 and the output of the high rotation signal detection circuit 5 are applied to the switch circuit 7 as operating signals.

The switch circuit 7 controls the application of the target injection amount signal SQ amplified by the amplifier circuit 6 to the injection amount control circuit 8 in accordance with the output of the low rotation signal detection circuit 4 or the high rotation signal detection circuit 5. When the output of at least one of the low rotation signal detection circuit 4 and the high rotation signal detection circuit 5 reaches a high level, the switch circuit 7 is activated and the amplified target injection amount signal SQ is immediately stopped. The input signal to the injection amount control means 8 becomes a signal that makes the amount of fuel injected into the diesel engine zero.

Further, when the outputs of the detection circuits 4 and 5 both become low level, the switch circuit 7 becomes inactive and the amplified target injection amount signal SQ is applied to the injection amount control means 8 as is.

The switch circuit 7 can be easily constructed using a relay or the like.

Next, the operation of the above configuration will be explained.

When everything is operating normally, a target injection amount signal SQ to the diesel engine is calculated in the fuel injection amount calculation circuit 3 based on the engine speed, and is amplified by the amplifier circuit 6.

On the other hand, since the engine rotation speed is higher than the first reference rotation speed and lower than the second reference rotation speed, the outputs of the low rotation signal detection circuit 4 and the high rotation signal detection circuit 5 are each at a low level.

Therefore, the switch circuit 7 is in a non-operating state, and the target injection amount signal SQ amplified by the amplifier circuit 6 is input as is to the injection amount control means 8, and the fuel to the diesel engine is controlled according to the magnitude of the target injection amount signal SQ. The injection amount is controlled to be optimal.

If the electromagnetic pickup of the rotation detection circuit 1 becomes unable to detect rotation due to disconnection, demagnetization, etc., the output voltage V of the conversion circuit 2
N is the rotation speed Qrp regardless of the actual engine speed
The voltage is equivalent to m, and the output of the fuel injection amount calculation circuit 3 is:
This becomes a signal to increase the fuel injection amount.

However, since the voltage VN becomes lower than the first reference voltage VL, the output of the low rotation signal detection circuit 4 becomes a high level, and the switch circuit 7 is activated to control the injection amount regardless of the magnitude of the target injection amount signal SQ. Since the input signal of the control means 8 is a signal that makes the fuel injection amount zero, fuel injection to the diesel engine is stopped and the engine is stopped immediately.

In addition, if for some reason the output of the fuel injection amount calculation circuit 3, the amplifier circuit 6, etc. fails in the direction of increasing the fuel injection amount, the engine speed increases, the DC voltage VN increases, and the second reference voltage When VH is exceeded, the output of the high rotation signal detection circuit 5 becomes high level, and the switch circuit 7 is activated.

Therefore, regardless of the magnitude of the output signal of the amplifier circuit 6, the input signal of the injection amount control means 8 is set to a signal that makes the fuel injection amount zero, so that the fuel supply to the diesel engine is stopped and the engine is stopped immediately. do.

As detailed above, according to the present invention, it is possible to prevent the engine from overrunning and being destroyed due to failure of the rotation detection circuit, fuel injection amount calculation circuit, amplifier circuit, etc., and is a practically effective invention. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. 1... Rotation detection circuit, 3... Fuel injection amount calculation circuit, 4... Low rotation signal detection circuit, 5.
. . . High rotation signal detection circuit, 7 . . . Switch circuit, 8 . . . Injection amount control means.

Claims (1)

[Scope of utility model registration request] a calculation means for inputting at least the rotational speed of the diesel engine as an electric signal and calculating an optimum fuel injection amount to the diesel engine based on the electric signal; and an injection for adjusting the fuel injection amount to the diesel engine according to the output of the calculation means. low rotation signal detection for detecting that the rotation speed of the diesel engine has become equal to or lower than a first reference rotation speed, which is equal to or lower than a predetermined rotation speed, based on the electric signal; means, high rotation signal detection means for detecting, based on the electric signal, that the rotation speed of the diesel engine has reached a second reference rotation speed that is higher than the maximum rotation speed set by the calculation means; and the low rotation speed. an electronic fuel injection amount switch means that is activated by the detection output of the signal detection means or the high rotation signal detection means and makes the input signal of the injection amount control means a signal that makes the fuel injection amount zero. Control device.