JPH0745832B2 - Diesel engine fuel injection pump - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection pump that is widely used in an internal combustion engine, particularly a diesel engine, and more specifically, supercharging fuel at the time of starting. And a fuel injection pump for a diesel engine configured as described above.

(Prior Art) A conventionally known fuel injection pump for a diesel engine includes a control sleeve that controls a fuel injection amount according to a displacement amount, and a control sleeve that operates in conjunction with an accelerator pedal and increases an accelerator pedal depression amount. A tension lever mechanism that biases the position of in the direction of increasing fuel,
A governor sleeve that displaces according to the engine speed,
And a governor lever mechanism that engages with the governor sleeve and biases the position of the control sleeve in the fuel reducing direction in response to an increase in the engine rotation speed.

In this type of fuel injection pump, when the engine is started, the control sleeve is urged in the fuel increasing direction by depressing the accelerator pedal. On the other hand, at this time, the governor sleeve that urges the control sleeve in the fuel reducing direction has a small influence on the operation of the control sleeve because the engine speed is low, so a large amount of fuel is injected at the time of starting. . That is, starting supercharging is performed, which can improve ignitability at the time of starting.

After the engine is started, the control sleeve is gradually displaced in the fuel reducing direction by the action of the governor sleeve, and the fuel injection amount is reduced. That is, the starting supercharging is stopped when the engine speed increases above a predetermined value.

However, since the startability of the engine is affected by the outside air condition, it is desirable to properly set the starting supercharging region according to the outside air condition.

From such a point of view, in the fuel injection pump disclosed in Japanese Utility Model Laid-Open No. 60-70739, the starting supercharging region is changed to the high rotation side of the engine to improve the starting performance when the ignition temperature is low. I am trying.

(Problems to be Solved) However, since the diesel engine is premised on self-ignition by adiabatic compression, the startability of the engine is greatly affected by the atmospheric pressure rather than the outside temperature. Therefore, when the atmospheric pressure is low, for example, in the highlands, there is a problem that the startup at the start is delayed.

In order to solve this problem, if the starting supercharging region is always expanded to the high rotation side regardless of the atmospheric pressure, there is a problem that smoke is generated at the time of starting in a normal atmospheric pressure state.

(Means for Solving the Problem) The present invention is configured in view of such circumstances,
It is an object of the present invention to provide a fuel injection pump for a diesel engine that can always ensure good startability regardless of changes in atmospheric pressure.

The fuel injection pump of the diesel engine of the present invention includes a starting supercharging mechanism that supercharges fuel in a region where the engine speed at the time of starting the engine is equal to or lower than a predetermined value, and an atmospheric pressure detecting unit that detects atmospheric pressure, It further comprises supercharging area changing means for changing the starting supercharging area. Then, when the atmospheric pressure is low, the supercharging area changing means,
It is characterized in that the starting supercharging is performed up to a higher rotation range than usual.

(Operation) A supercharging mechanism to which the present invention can be applied includes, for example, a fuel adjusting device that controls a fuel injection amount according to a displacement amount, and an increasing amount of depression of the accelerator pedal in conjunction with an accelerator pedal. An accelerator interlocking lever mechanism for urging the position of the fuel adjusting device in the direction of increasing fuel, a speed control mechanism that displaces in accordance with the engine speed, and a fuel control mechanism that engages with the speed control mechanism and increases in engine speed. And a speed adjusting lever mechanism for urging the position of the adjusting device in the fuel reducing direction.

Then, when the engine is started, the fuel adjusting device is urged in the fuel increasing direction by depressing the accelerator pedal. On the other hand, at this time, since the governor sleeve for urging the control sleeve in the fuel reducing direction has a low influence on the operation of the control sleeve because the engine speed is low, a large amount of fuel is injected.

When the rotation speed increases, the speed governing mechanism moves the fuel adjusting device in the fuel decreasing direction against the biasing force of the accelerator interlocking lever mechanism in the fuel increasing direction. As a result, the fuel injection amount begins to decrease, and the starting supercharging state ends.

In this case, the fuel injection pump of the present invention detects the atmospheric pressure,
A means for changing the starting supercharging region according to the change in atmospheric pressure is provided. This means may be constituted by, for example, a bellows mechanism that responds to changes in atmospheric pressure, and a transmission means that transmits the operation of the bellows mechanism to the speed control mechanism. The transmission means opposes the movement of the speed control mechanism. By
The starting supercharging region can be changed to the high rotation side according to the decrease in atmospheric pressure.

(Effect of the Invention) According to the above configuration of the present invention, the starting supercharging region is expanded to the high-speed rotation side by the action of the starting supercharging region changing means in response to the decrease in atmospheric pressure. This makes it possible to increase the combustion pressure and increase the starting torque when the engine is started in a low atmospheric pressure state such as in a highland, thereby shortening the starting time and improving the startability.

In addition, since the starting supercharging region is not changed to the high rotation side in a normal atmospheric pressure condition with good startability, problems such as smoke generation can be suppressed as much as possible.

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

Referring to FIG. 1, there is shown a partial cross-sectional view of a fuel injection pump to which the present invention can be applied.

The pump 1 includes a plunger 2 that supplies fuel, and a control sleeve 3 that is fitted to the plunger 2 and that changes the amount of fuel that is supplied according to the amount of displacement.

A pin hole 3a is formed in the control sleeve 3, and a ball head pin 5 attached to the lower end of the governor lever mechanism 4 is engaged with the pin hole 3a. The governor lever mechanism 4 includes a start lever 6, a tension lever 7 and a collector lever 8 which are integrally incorporated.
And is configured to be rotatable around the shaft 9. Then, the governor lever mechanism 4 swings the ball head pin 5 according to the magnitude of the resultant force acting on the levers 6, 7, and 8, thereby displacing the control sleeve 3 left and right in the figure. , The amount of fuel injection is changed.

The collector lever 8 regulates the maximum fuel injection amount, and is supported by the support spring 10 at the lower portion, so that the full load adjusting screw is used.
It is in contact with 8a.

One end of the tension lever 7 is engaged with a control lever mechanism 11 that responds to the operation of the accelerator pedal.
Then, as the depression amount of the accelerator pedal (not shown) increases, the control lever mechanism 11 moves to the left in the figure, and accordingly, the upper end of the tension lever 7 rotates to the left. To do. Therefore, the ball head pin 5 rotates to the right and biases the control sleeve 3 to the right. When the control sleeve moves to the right, the fuel injection amount decreases.

Also, one end of the start lever 6 has a governor sleeve 12
Is adapted to engage with the tip of the. Governor sleeve
The flyweight 13 is engaged with the flyweight 13. The flyweight 13 pushes out the governor sleeve 12 to the right in the figure as the engine rotation speed increases. As a result, the start lever 6 rotates to the right and urges the control sleeve 3 to the left, that is, in the fuel increasing direction via the ball head pin 5.

Further, a start idle spring 14 and a start spring 15 are interposed between the start lever 6 and the tension lever 7 to move the start lever 6 in the fuel decreasing direction and to increase the tension lever 7 in the fuel increasing direction. The movement of the springs 14 and 15 interferes with the elastic force of the springs 14 and 15. The start lever 6 and the tension lever 7 can relatively rotate around the shaft 9 within the elastic force range of the start idle spring 14 and the start spring 15, but a force exceeding this range acts. In that case, the start lever 6 and the tension lever 7 are interlocked.

In this way, the control sleeve 3 basically has
Positioning is performed at a point of harmony between the urging force of the start lever 6 in the fuel decrease direction due to the increase in the rotation speed and the urging force of the tension lever 7 in the fuel increase direction due to the increase in the accelerator pedal depression amount, and thereby the fuel injection amount is determined.

Referring also to FIG. 2, a bellows mechanism 16 that operates according to the atmospheric pressure of the pump 1 of the present example is provided, and the bellows mechanism 16 includes a chamber 17 that communicates with the atmosphere.
A bellows main body 18 which is disposed in the chamber 17 and in which a standard pressure gas is sealed is provided, and a plunger 19 which is attached to the bellows main body 18 and moves up and down in the drawing according to the movement of the bellows main body 18. . Further, the bellows body 18 is biased upward in the drawing by a spring 20. The plunger 19 has an inclined portion 19a at the lower end,
Further, a vertical portion 19b is provided below the inclined portion 19a.
A lever 21 having one end engaged with the inclined portion 19a or the vertical portion 19b is provided, and the lever 21 is rotatably attached around a pin 22 fixed to the pump 1.

The other end of the lever 21 is engaged with one end of a stopper 23 rotatably attached to the tension lever 7. Further, the other end of the stopper 23 is adapted to engage with the start spring 15.

When the atmospheric pressure introduced into the chamber 17 becomes lower than the gas pressure enclosed in the bellows main body, the bellows main body 18 has a spring depending on the magnitude of the atmospheric pressure.
It expands against the bias of 20 and pushes down on the plunger 19. One end of the lever 21 is normally engaged with the vertical portion 19b of the plunger 19, but when the plunger 19 moves downward due to a decrease in atmospheric pressure, the lever 21 comes into engagement with the inclined portion 19a. As a result, the lever 21 rotates leftward, and the stopper 23 rotates rightward. In the normal state, the stopper 23 is
Although flush with the tension lever 7, when the atmospheric pressure drops, the lever 21 is actuated to rotate rightward as described above to compress the start spring 15.

Next, the operation of starting supercharging in this device will be described.

When the accelerator pedal is depressed at the time of starting, the control lever mechanism 11 is displaced leftward, and the tension lever 7 is rotated leftward. As a result, the control sleeve 3 is displaced in the fuel increasing direction, that is, to the right in the figure. On the other hand, the governor sleeve 12 rotates the start lever 6 to the right according to the increase in the number of rotations. However, at the time of starting, the number of rotations is low, so the biasing force against the start lever 6 is small, and the start lever 6 is rotated. The amount of rotation is small. Therefore, in this state, the tension lever 7
The start idle spring 14 and the start spring 15 are compressed and displaced to the left, and the control sleeve 3 is moved to the right to increase the fuel. As a result,
Starting supercharging will be performed.

After that, when the rotation speed increases, the biasing force of the flyweight 13 increases, and the start lever 6 is rotated rightward against the biasing force of the tension lever 7, whereby
The control sleeve 3 is displaced to the left to reduce the fuel injection amount. As a result, the starting supercharging ends.

In this case, when the atmospheric pressure is in the normal state, there is no pressure difference between the chamber 17 of the bellows mechanism 16 and the bellows body 18, so that the plunger 19 remains stationary.
In this case, since the lever 21 does not rotate, and the stopper 23 is flush with the tension lever 7, the elastic force of the start spring 15 does not change.
As a result, the fuel injection amount changes as shown by the characteristic line a in FIG. That is, in the region where the engine speed is relatively low, the starting supercharging ends and the normal fuel supply state is entered.

Also, when starting at a low atmospheric pressure such as high altitude,
Since the air pressure inside the bellows body 18 becomes relatively higher than the pressure in the chamber 17, the bellows body 18 expands,
The plunger 19 is pushed down and the lever 21 is rotated as shown by the arrow in FIG.
Rotate so as to project from the surface. As a result, the start spring 15 is compressed and strengthens the elastic force that opposes the biasing force of the start lever 6 to the right.

As a result, the rotational speed for pushing the gas burner sleeve 12 and displacing the start lever 6 to give the flyweight 13 the urging force required to reduce the fuel so as to stop the starting supercharging is the same as the above-described normal rotation speed. It is higher than that under atmospheric pressure. Therefore, when the atmospheric pressure is low, the fuel injection amount changes as shown by the characteristic line b in FIG. That is, according to the configuration of the present example, when the engine is started in a low pressure state such as in a highland, the starting supercharging region is expanded to a higher rotation side than usual.

As a result, the fuel pressure in the low pressure state can be increased to increase the starting torque, and good startability can be obtained.

The lever 21 rotates due to the decrease in atmospheric pressure, and the stopper 23 is pushed by the lever 21 to expand the starting supercharging range to the high rotation side and to increase the high rotation range outside the starting supercharging range (running operation range). ), Since the lever 21 pushes the tension lever 7, the control sleeve 3 is moved somewhat in the direction of decreasing the fuel injection amount to improve the combustibility (overrich) in the highland where the oxygen amount is small, and prevent the increase of smoke. ing.

FIG. 4 shows another embodiment of the present invention.

In the structure of this example, the stopper 24 responsive to the bellows mechanism 16
Engages with the start idle spring 14 and strengthens the elastic force of the start idle spring 14 in response to a decrease in atmospheric pressure.

Even with this structure, the same effect as the previous example can be obtained.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a fuel injection pump according to one embodiment of the present invention, FIG. 2 is a partial sectional view showing an example of a starting supercharging changing means, and FIG. 3 is a fuel injection amount, FIG. 4 is a partial cross-sectional view showing another example of the starting supercharging changing means, which is a graph showing the relationship with the engine speed. 1 ... Pump, 2 ... Plunger, 3 ... Control sleeve, 3a ... Pin hole, 4 ... Governor lever mechanism, 5 ... Ball head pin, 6 ... Start lever 6, 7 ... Tension lever, 8 ... … Collector lever, 8a …… Full load adjusting screw, 9 …… Shaft, 10 …… Support spring, 11 …… Control lever mechanism, 12 …… Governor sleeve, 13 …… Fly weight, 14 …… Start idle spring, 15 …… start spring, 16 …… bellows mechanism, 17 …… chamber, 18 …… bellows body, 19 …… plunger, 19a …… sloping part, 19b …… vertical part, 20 …… spring, 21 …… lever, 22 …… Pin, 23,24 …… Stopper.

Claims (1)

[Claims] 1. A fuel injection pump for a diesel engine, comprising a working supercharging mechanism for supercharging fuel in a region where an engine speed at engine startup is equal to or lower than a predetermined value, wherein the pump detects atmospheric pressure. Means and a supercharging area changing means for changing the starting supercharging area, and when the atmospheric pressure is low, the supercharging area changing means is configured to perform the starting supercharging up to a higher rotation area than usual. A fuel injection pump for diesel engines, which is characterized by