JPS62159739A - Fuel injection quantity control device for diesel engine with turbo supercharger - Google Patents

Abstract

PURPOSE:To prevent production of smoke due to intake air flow rate drop phenomenon during the initial stage of acceleration, by a method wherein, in a device which increases a maximum fuel injection amount during supercharge, after the starting of acceleration, the maximum injection amount is set to a low value only during a given period. CONSTITUTION:When an engine is transferred from a non-supercharge state to a supercharge state as in an acceleration time, a controller 47 calculates an accel opening change rate from an accel opening signal, and when the change rate exceeds a set value, it is decided that the engine is brought into an acceleration state. When acceleration is decided, by exciting a relay 44a until an intake air pressure signal exceeds a set value, an electromagnetic valve 43 is switched, and a negative pressure from a vacuum pump 44 is introduced to a negative pressure chamber 40 of an actuator 37. In this constitution, an actuator 37 is driven, a full load lever 36 attached to a fuel injection pump is rotated clockwise through a rod 38, and a fuel injection amount is limited down to a level lower by a given amount than a maximum fuel injection amount level under a non-supercharge state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel injection method for a diesel engine equipped with a turbo supercharger and configured to increase the maximum fuel injection amount as the supercharging pressure increases. This invention relates to an injection amount control device.

(Prior art) In a diesel engine, there is a known technology for operating a supercharger in the high-speed region of the engine to increase the amount of intake air and increasing the amount of fuel injection accordingly to obtain high output. It is. For example, JP-A-55-96328
In the publication, the boost compensator (hereinafter referred to as "boocon") that controls the maximum fuel injection amount according to the intake pressure, that is, boost pressure, is used in a diesel engine with a supercharger.
A plurality of springs are provided in the engine, and as the boost pressure increases, the plurality of springs act in stages to increase the amount of fuel, thereby resolving the insufficient injection amount at high speeds.

(Problem to be Solved) In the injection amount control device using a booster for a supercharged diesel engine as disclosed in the above-mentioned Japanese Patent Application Laid-open No. 55-96328, when the engine speed increases due to acceleration etc. When the supercharger is activated and the boost pressure increases, the booster is activated to increase the injection amount. However, in a diesel engine that uses a turbocharger, the supercharging effect of the air pump is only obtained when the turbine rotation increases above a certain level due to an increase in exhaust gas pressure. Therefore, immediately after the start of acceleration, , the air pump rotation will increase with a slight time delay. Therefore, in the operating state immediately after the start of acceleration until the rotational speed of the air pump has sufficiently increased, the presence of the air pump will actually increase the intake passage resistance, causing a temporary drop in the intake air amount. . On the other hand, since the fuel injection amount is not corrected for this drop in the intake air amount, there is a problem in that an intake air shortage temporarily occurs and smoke occurs.

(Means for Solving the Problem) The present invention is configured to solve the above problem. A fuel injection amount control device for a diesel engine configured to set the maximum fuel injection amount to a predetermined amount smaller than the maximum fuel injection amount in a non-supercharging state for a predetermined period after the start of acceleration. It is characterized by

The injection amount control device according to the present invention preferably includes a booster that increases the maximum displacement amount of the control rack of the fuel injection pump during supercharging, that is, when boost pressure increases, thereby increasing the maximum fuel injection amount. .

In a preferred embodiment of the present invention, means for controlling the maximum displacement of the control rack is provided in addition to the control rack, and this means includes a lever member, preferably a diaphragm, for regulating the maximum displacement of the control rack. an actuator that drives a lever member;
Consisting of a vacuum pump that supplies operating negative pressure to this actuator, an electromagnetic control valve that is installed in a communication passage between the actuator and the vacuum pump that controls the supply of negative pressure to the actuator, and a controller that controls this electromagnetic valve. . Information such as engine speed, accelerator opening, and shift position is input manually to this controller.

The controller detects the initial state of acceleration based on the human input information, and outputs an opening command signal to the solenoid valve so that negative pressure from the vacuum pump acts on the actuator for a predetermined period after the start of acceleration.

This causes the lever member to rotate and displace the control rack by a predetermined amount in the fuel decreasing direction.

(Effects of the Invention) According to the present invention, when the accelerator pedal is depressed and an acceleration state starts, only for a certain period of time after the start of acceleration,
That is, at the beginning of acceleration, the maximum fuel injection amount is reduced by a predetermined amount from the normal maximum fuel injection amount, that is, the maximum fuel injection amount in a non-supercharging state. Therefore, even if a drop in intake air volume occurs due to a delay in the speed increase of the air pump of the turbocharger at the beginning of acceleration, the mixture will not become unduly enriched, eliminating the problem of smoke generation. be able to. The present invention can be applied not only to solving the problem of smoke at the early stage of acceleration, but also to other types of control. For example, when the boost pressure suddenly increases during acceleration, and as a result, the injection amount rapidly increases due to the activation of the booster, causing an acceleration shock, the control mechanism of the present invention is used to suppress the increase in the injection amount. By controlling as follows, acceleration shock can be prevented.

Furthermore, during deceleration, deceleration shock can be prevented by using the mechanism of the present invention to suppress the tendency for the fuel injection amount to decrease due to the operation of the booster. When applying the present invention to this acceleration/deceleration shock prevention control, it is desirable to take into consideration the amount of cargo load and perform it when the load is light, where acceleration/deceleration shocks are noticeable.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, an engine 1 to which the present invention is applied includes a piston 4 connected to a crankshaft 3 via a connecting rod 2, and this piston 4 is connected to a cylinder bore 5.
is arranged so as to be able to reciprocate and pivot freely within. The space above the piston 4 of the cylinder pore 5 constitutes a combustion chamber 6. An intake port 7 and an exhaust port 8 are open to the combustion chamber 6 . These ports 7 and 8 are combined with an intake valve 9 and an exhaust valve 10, as well as an intake passage 11 and an exhaust passage 1.
2 are connected to each other. Further, an air pump 14 of a turbocharger 13 is arranged in the intake passage 11, and a turbine 16 connected to the air pump 14 by a common shaft 15 and used to drive the pump 14 is arranged in the exhaust passage 12. Further, downstream of the turbine in the intake passage 11, a boost pressure detection pipe 17 is arranged to detect supercharging pressure, that is, boost pressure on the downstream side of the supercharger. This detection tube 17 is connected to a booster 18 that constitutes a fine injection control device for controlling the maximum fuel injection amount of the fuel injection pump. The boocon 18 has two chambers 20 separated by a diaphragm 19.
21, and the chamber 20 constitutes a pressurizing chamber into which boost pressure is introduced. In the other chamber 21,
A pressure spring 22 is arranged to urge the diaphragm 19 toward the pressurizing chamber 20 side. The diaphragm 19 also includes a bushing rod 22 that protrudes from the chamber 19.
a is attached, and the tip of the bushing rod 22a engages with one end of a lever 24 that is swingably attached to the pin 23. The other end of the lever 24 is engaged with one end of a bushing rod 25. The other end of the bushing rod 25 is in contact with a fixing pin 26 and a contact surface 28a of a U-shaped lever 28 rotatably attached to the fixing rod 27. A cancel spring 29 is attached to the rod 27 to bias the U-shaped lever 28 counterclockwise (arrow A in the figure). Further, a pin 30 is attached to the bent end of the U-shaped lever 28 on the side supported by the fixing pin 26.
is installed.

A sensor lever 31 is swingably attached to the pin 30. A U-shaped recess 31 is provided at one end of the sensor lever 31.
a is formed, and a pin 33 attached to the tip of a control rack 32 that controls the injection amount according to the amount of displacement is engaged with this recess 31a. Further, the other end side of the sensor lever 31 is in contact with a torque cam 35 fixed to the rod 34. Also, cancel spring 2
One end of the full load lever 36 is attached to the opposite side of the rod 27 to which the U-shaped lever 28 is attached, and the rod 38 from the actuator 37 is attached to the other end of the full load lever 36. It is connected.

Further, the lower end of the full load lever 36 comes into contact with the full load set screen 36a and bends.

Referring also to FIG. 2, the actuator 37 is
It is a diaphragm type, with a diaphragm 39 inside.
It's iffy. The diaphragm 39 is connected to the full load lever 36 via a rod 38 and defines a negative pressure chamber 40 . A spring 4 is provided in the negative pressure chamber 40.
1 is arranged to bias the diaphragm in the direction of the full load lever 36. The negative pressure chamber 40 is connected to a vacuum pump 44 via a negative pressure passage 42, and a three-way solenoid valve 43 is disposed between the actuator 37 and the vacuum pump. The solenoid valve 43 is a relay 44a
, batch! via switch 45 and switch 46! 14
6a. Further, the relay 44a is preferably turned on and off by a command signal from a controller 47 including a microcomputer, thereby switching the port of the solenoid valve 43 and controlling the operation of the actuator 37. It is supposed to be done. Signals such as engine speed, accelerator opening, and intake manifold pressure are input to the controller 47, and the controller 47 performs predetermined calculations based on these signals and issues commands to the relay 44a. Output a signal.

In the above structure, during non-supercharging when the supercharger is not operating, the intake pressure on the downstream side of the air pump 14 in the intake passage 11, that is, the boost pressure, is not so large, and the pressurizing chamber of the booster 18 has a There is not enough boost pressure to move the diaphragm. Therefore, diaphragm 19
is in its normal position on the right in FIG. 1, ie, in the position indicated by the dashed line. Therefore, the lever 24 is in the rightward rotated position and the push rod 25 is in contact with the U-shaped lever 28 when it has been moved to the left. Therefore, the sensor lever is moved to the right as shown by the dashed line and holds the control rod in the position shown by the dashed line. As a result, the fuel injection amount is not increased based on the boost control operation. Therefore, the maximum fuel injection amount is as shown in characteristic curve a in Fig. 3.
Changes in relation to rotation speed. Further, during supercharging, the boost pressure increases, so the diaphragm of the booster controller 18 is operated to the solid line position in the figure by the boost pressure acting within the pressurizing chamber 20.

As a result, each member 24, 25, 28, and 31 that interlocks with this diaphragm 19 moves to the solid line position in the figure, and the control rack 32 also moves to the solid line position in the figure.
Move to position. As a result, the fuel injection amount increases in accordance with the magnitude of the boost pressure generated. Therefore, the maximum fuel injection amount changes as shown in the characteristic curve in FIG.

Also, when transitioning from a non-supercharged state to a supercharged state, such as during acceleration, the intake pressure changes as shown in Figure 4D.
At the initial stage of acceleration, when the air pump 14 has not started operating, the air pump 14 acts as an intake passage resistance, so the air pressure tends to decrease and once drops below atmospheric pressure. After that, as the rotation of the turbine increases and the air pump 14 begins to exert a supercharging effect, the intake pressure begins to rise.
becomes higher than atmospheric pressure. In this way, in a state such as at the beginning of acceleration where the intake pressure tends to decrease and as a result, the intake air amount temporarily drops, in this example, the maximum fuel injection amount is set to the maximum fuel injection amount in the non-supercharging state. The amount is reduced by a predetermined amount. That is, the controller 47 of this example calculates the accelerator opening change rate from the input accelerator opening signal, and sometimes determines that an acceleration state has occurred when the change rate exceeds a set value. If it is determined that the acceleration state is present, a command signal is output to the relay 44a based on the signal detected at the intake manifold until the intake pressure exceeds the set value. As a result, the solenoid 43a of the electromagnetic valve 43 is excited, and negative pressure from the vacuum pump 44 is introduced into the negative pressure chamber 40 of the actuator 37. This activates the actuator 37, moves the rod 38 to the right in FIG. 1, and rotates the full load lever 36 clockwise. As a result, the U-shaped lever 28 and the sensor lever 31 rotate clockwise, moving the control rack 32 further to the right beyond the broken line position, and adjusting the fuel injection amount to the non-supercharging position as shown in FIG. The fuel injection amount is limited to a level indicated by line C, which is a predetermined amount smaller than the maximum fuel injection amount level a in the current state.

If the intake pressure exceeds the set value shown in FIG. 4, the controller de-energizes the relay 44a.

As a result, the introduction of negative pressure to the actuator 37 is stopped, and the full load lever 36 returns to its original position. Therefore, the U-shaped lever 28, the sensor lever 31, and the control rack 32 return to their original positions, that is, the positions shown by the broken lines in the figure, due to the elastic force of the cancel spring 29. That is, the maximum fuel injection amount returns to level a of the normal non-supercharging state. After that, when the intake pressure increases further, due to the action of the booster controller 18, the maximum fuel injection amount becomes
The injection amount increases to the maximum injection amount level b during supercharging. Therefore, in the control of this example, the maximum fuel injection amount changes as shown by the solid line d in FIG. Therefore, in the past, despite a drop in intake air volume at the beginning of acceleration,
As a result of the fuel loss being corrected and being maintained at the normal non-supercharging level ai as shown by the broken line e in Figure 3, there was a problem that air intake was insufficient during this period and smoke was generated. However, this problem can be solved by controlling the injection amount as in this example.

The present invention can be used not only to eliminate the occurrence of smoke in the early stages of acceleration, but also to other types of control.

For example, if the amount of cargo load on the vehicle is manually input to the controller 43, and there is sudden acceleration when the amount of cargo load is light, the actuator 37 is operated for a certain period of time from the start of acceleration.
By activating this to suppress the sudden increase in fuel weight, the acceleration shock can be alleviated. Furthermore, when the load amount is large, sufficient acceleration performance can be obtained by canceling such restrictions.

[Brief explanation of drawings]

Fig. 1 is an overall view of the fuel injection amount control device of the present invention and a diesel engine equipped with the device, Fig. 2 is an explanatory diagram of the operation of the control device of Fig. 1, and Fig. 3 is the maximum fuel injection amount. FIG. 4 is a graph showing changes in intake pressure during acceleration. 1...Engine, 4...Piston, 11...Intake passage, 12...Exhaust passage, 13...Supercharger, 18・・・・・・
・Boocon, 19...Diaphragm, 28
...U-shaped lever, 31...Sensor lever, 32...Control rack, 36...
・Full load lever, 37... Actuator, 43... Three-way solenoid valve, 44... Vacuum pump, 47... Controller.

Claims (1)

[Claims] A fuel injection amount control device for a diesel engine equipped with a turbo supercharger and configured to increase the maximum fuel injection amount during supercharging, the device increasing the maximum fuel injection amount in a non-supercharging state for a predetermined period after the start of acceleration. 1. A fuel injection amount control device for a turbocharged diesel engine, comprising a control device for setting a maximum fuel injection amount that is smaller by a predetermined amount.