JPS5936664Y2 - distribution type fuel injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distributed fuel injection pump for an internal combustion engine in which a history characteristic (hysteresis) is given to the fuel injection amount over a normal rotational speed range from the time the engine is started.

A distribution type fuel injection pump used in an internal combustion engine such as a diesel engine pressurizes and distributes fuel to each cylinder of a multi-cylinder internal combustion engine using a plunger that rotates and reciprocates in conjunction with the output shaft of the engine. By displacing the control sleeve into which the plunger is slidably fitted, the amount of fuel discharged from the plunger is changed to control the amount of fuel injected by the pump.

Conventionally, as shown in Fig. 1, the speed regulating mechanism of this type of pump is generally configured to move around a common fixed fulcrum 3 in response to the movement of the governor shaft 2 caused by the expansion of the flyweight 1 as the engine speed increases. The control sleeve 8 is displaced by rotating a start lever 4 and a tension lever 5, which are rotatably attached to each other, against the forces of a start spring 6 and a governor spring 7, respectively.

The injection quantity characteristics of the conventional distribution type injection pump having such a configuration when the control lever (not shown) is set to the starting position (same as the full load position) are as shown by the solid line in FIG.
The injection amount changes along the line a-b where the fuel is supercharged by the start spring 6 which presses the start lever 4 in the fuel increasing direction when the engine is started, and then when the flyweight 1 changes as the engine speed increases. A state in which the expansion force exceeds the force of the start spring 6 and the start lever 4 rotates in the direction of fuel reduction. After passing b - c, the star I lever 4 contacts the tension lever 5 and the injection amount remains approximately constant. c.
-d.

Finally, start spring 6 and tension lever 5
Since the strength of the idle spring 9 that presses the engine in the fuel increasing direction is relatively weak, the actual injection amount changes from the fuel supercharging state a - d to the full load fuel amount state c - d at a relatively low engine speed N'1. Particularly during a cold start, it may take a long time for the engine to fully detonate, or there is a risk that the engine may stop before it fully detonates.

Therefore, if the strength of the start spring 6 and the start idle spring 9 is designed to be larger so that the injection amount reaches the state c - d at a higher rotation speed N1 as shown by the broken line in Fig. 2, it is possible to start the engine. In a normal rotational speed range other than the above, the amount of injection becomes excessive, resulting in severe smoke generation, resulting in fuel consumption and pollution problems.

Therefore, when starting the engine, the state of fuel supercharging is maintained up to a higher rotational speed N'1 as shown by the broken line, while in the normal operating speed range N'1-N1 other than when starting the engine, as shown by the solid line. There is a need for an injection pump that can exhibit conventional injection quantity characteristics.

The present invention has been developed in view of the above-mentioned circumstances, and an embodiment thereof will be described with reference to FIG.

In the figure, the governor shaft 2 is the camshaft 1 of the injection pump.
The flyweight 1 is slidably attached to the pump body 11 so as to be displaced by opening and closing of the flyweight 1, which is driven according to the rotational speed of the engine.

A start lever 4 made of a magnetic material is rotatably attached to a pin 12 on the pump body 11, and a pin 4a at one end engages with a recess in a control sleeve 8 into which a plunger 13 is slidably fitted. One end of a start spring 6 is attached to the other end so that the start lever 4 always comes into contact with the free end of the governor shaft 2.

The plunger 13 is provided coaxially with the camshaft 10 and rotates and reciprocates to distribute fuel under pressure to each cylinder of the engine via a delivery valve.

A tension lever 5 is rotatably attached to the pin 12 to which the start lever 4 is attached.
is brought into contact with one side of the other end, that is, the free end, of the start spring 6 and acts as a supporting member thereof, and
When the start lever 4 rotates about the pin 12 due to movement of the governor shaft 2, it comes into contact with the upper end of the start lever 4 and rotates together.

The fuel injection amount is adjusted by rotating the start lever 4 or the tension lever 5 about the pin 12 and displacing the control sleeve 8 by the pin 4a.

The start spring 6 acts to rotate the start lever 4 so as to move the control sleeve 8 in the fuel increasing direction (to the right in the figure) in order to increase the amount of fuel at the time of starting.

A governor spring 7 is attached to the other end of the tension lever 5 via a start idle spring 9, and the governor spring 7 is connected to the accelerator pedal of the vehicle via a control lever (not shown), and is used when starting the engine or at maximum rotation. In the position, move the tension lever 5 to the main body 1.
It is designed to be pulled until it hits a full load stopper 14 provided at 1.

A stop lever 15 is rotatably provided on the pump body 11 via a torsion coil spring (not shown).
It is composed of a lever part 15a provided at J, and an actuating part 15b which is provided integrally with the lever part 15a and is disposed inside the pump body facing the upper end of the start lever 4. The portion 15b presses the start lever 4, causing the lever 4 and the tension lever 5 to rotate about the pin 12, and the control sleeve 8
The engine is moved to the no-injection position regardless of the position of the control lever to stop the engine, and is normally held in the non-injection position by the action of the torsion coil spring.

According to the present invention, the actuating part 15 of the stop lever 15
A permanent magnet 16 is attached to the tip of b, and the operating part 1
The upper end of the start lever 4, which faces the start lever 5b, is attracted and held by the magnet 16 from when the engine is stopped until it reaches a constant rotational speed after starting the engine.

The operation of such a configuration will be explained with reference to FIGS. 4 and 5.

FIG. 4 shows the attraction force F and displacement of the start lever 4 by the magnet 16 with respect to the engine speed N of the injection pump of the present invention, and FIG. 5 shows the injection amount Q with respect to the engine speed N.

This state occurs when the control lever (not shown) connected to the governor spring is set to the starting position, that is, the full load position, and when the engine starts, the governor moves as the flyweight 1 expands as the rotational speed increases. shaft 2
A pressing force of 2 acts on the start lever 4, but due to the magnetic force of the magnet 16, the attracted force F and the displacement of the start lever 4 change as shown by the rightward arrow in FIG.
Correspondingly, the injection amount Q also changes as shown by line A in Fig. 5, while when the engine speed decreases, the injection quantity Q changes along line A as shown by the leftward arrow in Fig. 4. It changes along →B→2, and depicts a so-called hysteresis characteristic.

Specifically, when the engine starts, the start lever 4 does not displace even when it reaches the rotation speed N1 at which the conventional supercharging state at startup ends, and remains attracted to the magnet 16 until it reaches a higher predetermined rotation speed N2. Therefore, supercharging is performed by an increased amount Q1 over the rotational speed N1 to N2.

Next, at N2, the pressing force of the governor shaft 2 exceeds the attraction force F2 of the magnet 16, and the restart lever 4
Since it rotates clockwise as shown in Fig. 3 while deflecting the start spring 6, as shown in Fig. 4, the attracted force F and the displacement are along the direction I → Mouth →. The injection amount decreases by Ql.

The 0 point corresponds to when the start lever 4 contacts the tension lever 5, and in the low range, the tension lever 5 is pressed by the governor shaft 2, but as the control lever is set to the full load position as described above, the governor Since the tension of the spring 7 is large, it does not rotate and the injection amount is kept substantially constant.

In addition, if the rotation speed increases further than point C, the tension lever 5 is rotated only by the centrifugal force of the flyweight 1 (
(The start lever 4 also rotates together), and a general speed regulating action is performed.

On the other hand, when the engine speed decreases and reaches the speed N2, the start lever 4 is still in contact with the tension lever 5, and the start lever 4 is at the displacement D1 and is away from the magnet 16. The attracting force F by the magnet 16 is weaker than the attracting force F2 in the attracting state during the favorable operation, and the governor shaft 2 due to the expansion of the flyweight 1
Since the pressing force has not yet weakened, the start lever 4 is not attracted to the magnet 16 and the injection amount does not increase.

As the rotational speed further decreases and the governor shaft 2 retreats to the left in FIG. 3, the compound eye attraction of the start lever 4 due to the magnet 16 gradually increases as shown in the curve Rho 2, and its position changes to the corresponding curve opening → When the rotational speed reaches N1, the attracted force becomes equal to F2, and the start lever 4 is attracted to the magnet 16.

As described above, the start lever 4 and the magnet 16 are at the same rotation speed N2 when the engine speed is rising and when it is falling.
As shown in FIG. 4, the attracted force exerted on the start lever 4 differs depending on the positional relationship between Curve B during normal driving, including when descending.
This shows the history characteristic (hysteresis) that changes along the curve.

As explained above, according to the present invention, a magnet is attached to the tip of the stop lever located inside the main body of a distribution type fuel injection pump for an internal combustion engine, and the stop lever is placed in the main body of the internal combustion engine. By attracting and holding the start lever on the magnet to maintain the supercharged state of fuel at the time of starting the aircraft, and injecting an appropriate amount of fuel after the start lever separates from the magnet, This not only improves engine startability but also ensures an appropriate amount of injection in the normal rotational speed range, ensuring comfortable operation without smoke generation.

The above explanation was based on the case where the engine was started with the control lever set at the full load position, but in this invention, when the engine stops, the start lever is displaced to the fuel supercharging position by the magnet of the stop lever. This makes starting the engine extremely easy, as starting supercharging can be obtained even if the control lever is set to the no-load position without pressing the accelerator pedal.

[Brief explanation of drawings]

Fig. 1 is a partial diagram of a conventional distribution type fuel injection pump, Fig. 2 is a graph of the injection quantity characteristics of the conventional injection pump, Fig. 3 is a partial cross-sectional front view of an embodiment of the present invention, and Fig. 4 is a graph of the injection quantity characteristics of the conventional injection pump. FIG. 5 is a graph showing the suction force and displacement of the start lever with respect to the engine speed of the injection pump of the present invention. FIG. 5 is a graph showing the injection amount characteristics with respect to the engine speed of the injection pump of the present invention. 1...Fly weight, 4...Start lever 5...Tension lever, 6...
...Start spring, 7...Governor spring, 8...Control sleeve, 9...
...Start idle spring, 13...
Plunger, 14... Full load stopper, 15... Stop lever, 16...
Hyaku magnet.

Claims (1)

[Scope of utility model registration request] A stop lever and a start lever disposed inside the main body of a distribution injection pump for internal combustion engines are attracted to each other by a magnet attached to one of the levers, and both levers are attached to each other from the time the engine is started until a predetermined rotational speed is reached. A distribution type fuel injection pump characterized in that the fuel supercharging state is maintained at the time of starting the engine by adsorbing and holding the levers to each other, and an appropriate amount of fuel can be injected after the levers are disengaged.