JPS5822994Y2 - fuel injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection pump, and in particular, is designed to obtain complex advance angle characteristics by controlling internal pressure characteristics.

With conventional fuel injection pumps, the fuel pressure inside the pump housing (hereinafter referred to as internal pressure) is controlled only by the internal pressure regulating valve, so as shown in Figure 1, the fuel pressure inside the pump housing is To increase.

Therefore, depending on the timer piston, which is actuated by internal pressure to control the fuel injection timing (advance angle characteristic), only a linear advance characteristic as shown by the solid line in Fig. 2 can be obtained; However, only the characteristics shown by the dotted line in FIG. 2 can be obtained.

Incidentally, in recent years, methods have been taken to reduce NOx emissions by delaying the injection timing as an exhaust gas countermeasure, but with conventional injection pumps, it is impossible to retard the injection timing within a certain rotation range. Therefore, the engine can be retarded only in a certain rotation range without reducing maximum output.
It is difficult to reduce the emissions of x.

Therefore, the present invention has a simple structure by providing a fuel relief passage in the timer piston, internal pressure regulating valve, or other parts operated by the pump internal pressure, and opening and closing this relief passage according to the internal pressure to change the internal pressure characteristics. The purpose of this is to obtain complex advance characteristics in which the fuel injection timing is delayed or advanced only in a certain rotation speed range.

The present invention will be described below with reference to embodiments shown in the drawings.

First, a first embodiment shown in FIGS. 3 and 4 will be described.

Although FIG. 3 is a front sectional view, only the timer piston 10 portion is a right side sectional view.

The timer piston 1 has a high-pressure side fuel passage 1a and is slidable within a timer cylinder 2 provided in a pump housing H.

- The housing H is filled with fuel pressurized by the feed pump 3, and the pressure is led to the chamber 1b on the right side of the timer piston 1 via the high-pressure side fuel passage 1a.

The left side of the timer piston 1 communicates with a low-pressure side fuel passage 4 upstream of the feed pump 3.

As the fuel pressure (internal pressure) on the high pressure side increases,
Overcoming the load of timer spring 5, timer piston 1
moves to the left.

This movement rotates the roller Nilingua through the connecting rod 6.

Face cam 8 and plunger 9 are connected to pump shaft 1
0, the plunger 9 rides on the roller 11 in the ring 7 and moves to the right.

The reciprocating rotation of the plunger 9 distributes and supplies fuel to each cylinder of the engine (not shown).

The internal pressure regulating valve 12 is pushed upward by the internal pressure and is urged downward by the internal pressure regulating spring 13, and opens the passage 14 when the internal pressure exceeds a predetermined value.

The above configuration is exactly the same as that of the conventional injection pump, but in the present invention, a small diameter internal pressure relief passage 1c having a throttling effect is formed in the timer piston 1, and the passage 1c is also formed in the pump housing H. An internal pressure relief passage 15 is formed adjacent to the housing H, and when the timer piston 1 moves to the left by a predetermined amount, the inside of the housing H communicates with the low pressure side fuel passage 4 through the two internal pressure relief passages 1c and 15. I try to let them do it.

In the above configuration, when the internal pressure rises as the rotational speed increases, the pressure in the chamber 1b of the timer piston 1 also rises, overcoming the force exerted by the timer spring 5 and causing the timer piston 1 to rise.
moves from the high pressure side to the low pressure side (left side), and this movement of the timer piston 1 causes the roller ring 7 to move through the connecting rod 6.
is rotated in the opposite direction of pump rotation to advance the injection timing as before.

As the internal pressure rises, the two internal pressure relief passages 1c and 15 communicate with each other at the point when the internal pressure moves to a certain position (the point corresponding to the rotational speed Nl in Figs. 5 and 6), and the fuel on the high pressure side is released. The fuel flows into the low pressure side fuel passage 4, and the rate of increase in internal pressure with respect to the rotational speed decreases, and the advance angle is stopped.

However, since the internal pressure relief passage 1C has a throttling effect, the internal pressure gradually increases as the rotational speed increases, and the timer piston 1 also moves leftward little by little, corresponding to the rotational speed N2 in FIGS. 5 and 6. At the point when the two escape passages 1c, 1
5 is cut off, and the internal pressure characteristics and advance angle characteristics return to the same as before.

Therefore, the internal pressure characteristics and advance angle characteristics are as shown by the solid lines in Figs. In addition, in the rotation range of N2 or higher, the same advance characteristic as the conventional one can be obtained, so that the same output as the conventional one can be obtained.

Next, a second embodiment shown in FIG. 7 will be described.

In the above embodiment, the timer piston 1 has an internal pressure relief passage 1c.
However, here, the internal pressure relief passage 1 is provided in the internal pressure regulating valve 12.
2a, and an internal pressure relief passage 15a is also formed in the housing H adjacent to this passage 12a.

And also by this, 2
The two relief passages 12a and 15a communicate with each other to reduce the rate of increase in internal pressure relative to the rotational speed, resulting in the same effects and effects as in the first embodiment.

In the above embodiment, the internal pressure relief passages 1c and 12a were changed from closed to opened to closed as the rotational speed increased, but this was changed from open to closed to closed.
By changing to the open position, the characteristics shown by the one-dot chain line in FIGS. 5 and 6 can be obtained, and the angle can be advanced in a certain rotation range.

In addition, other than the timer piston 1 or the internal pressure regulating valve 12, parts operated by internal pressure may be used, or new parts may be installed.
A similar effect can be obtained by providing an internal pressure relief passage in them to adjust the internal pressure.

As described above, in the present invention, a passage is formed in a member operated by internal pressure to release high-pressure fuel to the low-pressure side, and this passage is configured to open and close according to increases and decreases in internal pressure (increases and decreases in rotational speed). The internal pressure characteristic, which conventionally had a linear relationship with the rotation speed, can be changed only in a certain rotation speed range as necessary, so it can be changed within a certain rotation speed range without using special springs or mechanisms. This provides an excellent effect in that the injection timing can be advanced or retarded.

[Brief explanation of drawings]

Figures 1A and 2 are characteristic diagrams for explaining the operation of a conventional pump, and Figure 3 is a front cross-sectional view showing the first embodiment of the pump according to the present invention (however, the timer piston 1 button and the timer FIG. 4 is a right side sectional view taken along line A-A in FIG. 3, FIGS. 5 and 6 are characteristic diagrams for explaining the operation of the pump of the present invention, and FIG. The figure is a sectional view showing the main parts of a second embodiment of the pump according to the present invention. DESCRIPTION OF SYMBOLS 1... Timer piston forming a control member, 1c... Internal pressure relief passage, 4... Low pressure side fuel passage, 12... Internal pressure regulating valve forming a control member, 12a... Internal pressure relief passage,...・Pump housing.

Claims (1)

[Scope of utility model registration request] A button on the fuel injection pump including a timer piston that controls fuel injection timing in response to high pressure fuel pressure in the pump housing, and a control member responsive to the high pressure fuel pressure;
An m pressure relief passage is provided to release the high pressure fuel pressure to the low pressure side, the internal pressure relief passage is opened or closed when the control member moves a predetermined amount, and the internal pressure relief passage is opened or closed when the control member moves a further predetermined amount. A fuel injection pump characterized in that the pump is configured to close or open.