JPS61200336A - Output control method for internal-combustion engine - Google Patents

Abstract

PURPOSE:To enhance the fuel consumption and achieve the reduction of noise at the time of low load by determining governor characteristic for controlling an engine so that the engine revolution is decreased in response to the torque difference in case torque has decreased below a prescribed torque. CONSTITUTION:Where discharged oil of pumps 2a and 2b driven by an engine 1 is supplied to actuators 3a and 3b via valves 4a and 4b, pumps 2a and 2b are controlled by servomotors 5a and 5b via control valves 6a and 6b connected to their delivery sides respectively. Each of the servomotors 5a and 5b is controlled by a control device 7 in accordance with the operating conditions of the engine. Here, the control device 7 is so constituted that the governor characteristic with regard to the relationship between the engine output and engine revolution is determined so that the engine revolution is decreased in response to the torque difference in case torque has decreased below a prescribed torque, and that the engine 1 is controlled in accordance with this governor characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling the output of an internal combustion engine.

In conventional mechanical all-speed governor type fuel injection systems, the fuel consumption amount is uniquely determined from the governor characteristics and the equal fuel efficiency curve of the engine. FIG. 5 is a diagram showing this situation, in which the equal fuel consumption curve α1. α2. α3. ..., the governor characteristic diagram 6 changed linearly from its rated point C.

Problems to be Solved by the Invention In the conventional example described above, there was a problem in that the fuel consumption rate at low load was high in the governor characteristic diagram, and the fuel efficiency was poor.

Means and Effects for Solving the Problems The present invention was conceived in view of the above-mentioned problems.When the governor characteristic in the relationship between engine output torque and engine speed is reduced to a preset torque, By reducing the engine speed in accordance with the torque difference, it is possible to improve fuel efficiency and reduce noise at low loads.

Example Embodiments of the present invention will be described based on the drawings.

FIG. 3 schematically shows a control system for an engine and a pump to which the present invention is applied. In the figure, 1 is an engine, 2a and 2b are pumps, and 3α.

3b is a pulp 4α for each pump 2α, 2b.

This is an actuator connected via 4b. 5α.

5h is a servo motor that controls each of the pumps 2α, 2h, each of which is a control valve 6α.

It is connected to the discharge side of each pump 2α, 2A via 6b.

7 is a control device with a built-in microcomputer, and 8α.

8b is an electric lever that controls this. 9 is a fuel injection device with an electronic cabana; 10 is a governor potentiometer for detecting the throttle lever position; 11 is a rack position detecting device; 12 is a rotation sensor for detecting the rotation speed of the engine 1; Detection value and the above servo motor 5α.

A position detection signal 5b is applied to the control device 7.

The control device 7 processes signals from the rotation sensor I2 and the governor potentiometer 10 with a microcomputer, outputs an appropriate rack position signal, and adjusts the fuel injection amount.

That is, in Fig. 1, the governor characteristic curve of a mechanical all-speed governor is shown for the rated point C of the engine output. The rotational speed is controlled so that it passes through the minimum fuel efficiency point like the CE curve.

The method for determining the CE curve is as follows.

In Figure 1, the fuel consumption rate at a certain horsepower Pa (pz:') for the conventional mechanical all-speed governor type is calculated from the equal fuel consumption curve αs Cg/pE, h)
However, when looking at this on the equal horsepower line d, α! ωΔ9. h)
It turns out that there is another fuel efficiency point. Finally, aH
<Since it is aH, for engine 1, point A is p
Using it at point B can reduce fuel consumption.

If we find the minimum fuel efficiency point for every horsepower in this way, will it look like a CE curve? ), it is possible to reduce fuel consumption by changing the CD curve.

Note that when the control method according to the present invention is used for a yarn including a hydraulic pump as shown in FIG. 3, there is a risk that the speed of the shear actuator will change due to changes in the engine speed at low loads, so the pump discharge amount Ql The pump swash plate angle is controlled so that /m1n=engine speed Nrprn×pump discharge capacity qc, c/reν=constant.

The control system according to the present invention will be explained below using the block diagram shown in FIG.

First, the pump discharge pressure detector 13 outputs the actual pump discharge pressure as a signal P, the pump displacement amount detector 14 outputs the actual pump discharge amount at that time as a signal X, and the arithmetic unit 1
Enter 5. As a result, the load torque of the pump is calculated and the torque signal T is output from the calculation unit 15, and the calculation unit 16 is manually operated to compare the torque signal T with the target torque T0 set in advance by the throttle lever. Only when the torque is down, the torque difference is expressed as the torque deviation signal ΔT.
(=T0-T).

This means that the engine 1 has started acting in the light load direction, and is the premise for setting the CE curve in FIG. signal 4
is input to the first function generator 17 to generate the rotational speed deviation signal ΔN
Convert and output.

The first function generator 17 stores in advance the relationship between ΔT and ΔN so as to form the CE curve shown in FIG. This ΔN is calculated by the second, third, and fourth function generators Ig, 19
．． Enter 20. The second function generator 18 converts it into a rack displacement signal M to set the fuel injection amount Y, and the third function generator 19 sets the fuel injection timing time t. For example, the larger the rotational speed difference ΔN caused by the torque reduction, the more the rack displacement M is reduced, the fuel injection timing t is increased (later), the fuel injection amount Y in the fuel injection device 9 is reduced, and the engine rotational speed is lowered. I will do it. In the fourth function generator 20, in order to cover operational problems caused by a sudden change in the pump discharge amount due to a decrease in the engine speed, ΔN is used as the pump tilt amount. Converting the signal to a signal
Keep the pump discharge rate constant. For example, the more the engine speed decreases (the larger ΔN is), the larger the pump displacement signal X becomes, and therefore the pump discharge amount is kept constant.

FIG. 2 shows a state in which a CE curve is drawn by the above ΔT and ΔN. T in the figure. , Nr is a target value (initial value) determined by the throttle lever.

Effects of the Invention According to the present invention, it is possible to improve fuel efficiency at low loads, and to reduce noise caused by a reduction in engine speed at low loads.

[Brief explanation of the drawing]

FIG. 1 is a governor characteristic diagram according to the method of the present invention, FIG. 2 is an enlarged explanatory diagram of the governor characteristic diagram, FIG. 3 is a block diagram showing the control system of the method of the present invention, and FIG. 4 is a diagram showing the control system of the method of the present invention. A circuit diagram showing an example of application, and FIG. 5 is a governor characteristic diagram according to a conventional method.

Claims (1)

[Claims] An internal combustion engine characterized in that a governor characteristic in the relationship between engine output torque and engine rotational speed is such that when the torque is reduced relative to a preset torque, the engine rotational speed is reduced in accordance with the torque difference. Output control method.