JPS608343B2 - fuel injection pump - Google Patents

Description

[Detailed description of the invention] The present invention relates to improving the performance of fuel injection pumps.

A conventional fuel injection pump is shown in FIGS. 1 and 2. In the figure, 1 is a fuel cam, 2 is a cam 0-F, 3 is a pump spring, 4 is a rack for fuel injection amount control, 5 is an oil supply hole provided in the plunger barrel 7, and 6 is a plunger. It reciprocates within the barrel 7 and rotates around the axis by the fuel injection amount control rack 4.

8 is an oil drain hole provided in the plunger barrel 7, and the upper edge of the oil supply hole 5 and the upper green of the oil drain hole 8 are at the same height. A plunger chamber 9 is a space surrounded by the upper surface of the plunger 6 and the plunger barrel 7.

10G fuel pump main body, 11 is a discharge valve located at the upper part of the plunger chamber 9.

12 is a discharge valve spring, 13 is a fuel injection pipe, and 14 is a plunger lead, which is a notch provided in the plunger 7.

FIG. 3 is an exploded view of the plunger and plunger barrel showing the relative positional relationship between the plunger lead and the oil supply hole 9E depending on the load.

If the plunger 6 rises due to the rotation of the fuel cam,
The oil supply hole 5 and oil drain hole 8 are gradually closed on the side surface of the plunger 6, and the oil pressure in the plunger chamber 9 increases.

When this oil pressure becomes greater than the valve pressure of the discharge valve spring 12, the discharge valve 11 is pushed up to start discharging fuel. If discharge begins before the oil supply hole 5 and oil drain hole 8 are completely closed, this is called preflow. Oil supply hole 5 and 9E oil hole 8
After the is completely closed, the plunger rises further,
When the lead 14 shown in FIG. 2 hits the oil drain hole, the oil pressure in the plunger chamber 9 decreases. Even if this oil pressure decreases, if the discharge valve amount 1 is pushed up, the discharge continues, and if the oil pressure decreases further and the discharge valve 11 closes, the discharge ends. If oil is discharged even after the oil hole 9E is closed by the lead 14, this is called afterflow. Also, “Plunger 6
The moving distance of the plunger from when the oil supply, oil drain hole 5, and seal are completely closed until the lead 14 touches the oil drain hole 8 is called an effective stroke, and is indicated by hH and hL in FIG. 3. The amount of fuel to be discharged is controlled by rotating the plunger 6 by means of the t-pump rack 4, changing the relative position between the lead 14 and the oil drain hole 8, and changing the effective stroke as shown in FIG. conduct. In addition, the conventional salary, 8
E Regarding the size of the oil hole, the oil supply hole needs to be of a certain size in order to {1) prevent the injection period from extending and (2- prevent the pump efficiency from decreasing; (1) A certain amount of size is required to improve the sharpness of the injection.

Changes in the fuel injection amount when the position of the pump rack 4 of the above pump is kept constant and the pump rotation speed is changed, and fuel injection amount when the pump rotation speed is kept constant and the pump rack position is changed. The changes are shown by solid lines in FIGS. 4 and 5, respectively.

As shown in FIG. 4, the injection amount suddenly decreases at low rotation speeds, and as shown in FIG. 5, the increase in injection amount per change in latch position (6qf/6Rc) is small. For this reason, as shown in FIG. 6, when the pump rack is constant, the output torque of the engine may suddenly decrease at low speeds, and the performance at low speeds under load may become unstable.

In order to compensate for this, attempts have been made to correct the fuel injection quantity characteristics using a governor, but due to insufficient governor control power at low speeds and the small 6qf/6Rc shown in Figure 5 and nonlinearity, Therefore, correction using only the governor is difficult. Basically, it is necessary to improve the fuel injection amount characteristics as shown by the broken lines in FIGS. 4 and 5. As a means to increase the increase in injection amount per rack position change in the low load range, there is a two-stage lead that increases the slope of the plunger lead in the low load range, as shown in Figure 7. , this cannot improve the above-mentioned drawback that the injection amount suddenly decreases at low speeds.

The object of the present invention is to provide a fuel that can improve the sudden drop in fuel injection amount at low speed and low load operation, and can increase the increase in fuel injection amount per pump rack position change at low speed and low load operation. The purpose of the present invention is to provide an injection pump, and its features are as follows.

[11 Two sets of pictures and scarlet oil holes of different sizes are provided, and two leads are provided on the plunger. A small picture and oil drain hole are used for a low load castle, and a large supply and oil drain hole are used for a high load castle. and ■ The plunger has two leads with different inclinations, so that the lead with a larger inclination is used in low load ranges, and the lead with a smaller inclination is used in high load ranges.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 8 is a cross-sectional view showing a fuel injection pump according to an embodiment of the present invention, FIG. 9 is a perspective view showing a cross-section of the plunger, plunger lead, and plunger barrel, and FIG. An explanatory view showing a cross section of the scale oil hole, FIG. 11a is a developed view of the plunger head, and FIG. 11b is a developed view of the plunger barrel head showing the position of the oil supply and drain hole.

In the figure, 1 is the fuel cam and 2 is the cam.

3 is a pump spring t, 4 is a rack for fuel injection amount control, 5a is a small diameter oil supply hole provided in the plunger barrel 7, 5b is a large oil supply hole, which is provided in the plunger barrel 71, and a small diameter oil supply hole 5a. The closed area is larger, and the upper green of the small diameter oil supply hole and the upper green of the large diameter oil supply hole are at the same height.
Reference numeral 6 denotes a plunger, which is reciprocated within the plunger barrel 7 by a fuel cam and rotated around an axis by a fuel injection amount control rack 4.

Reference numeral 8a denotes a small oil drain hole, which is provided with a plunger barrel T', has the same closed area as that of the small diameter oil supply hole 5a, and has an upper edge at the same height as that of the small diameter oil supply hole 5a.

8b is a large diameter pseudo oil hole, which is provided in the plunger barrel 7;
The closed area is the same as that of the large diameter oil supply hole 5b, and the upper edge is at the same height as that of the large diameter oil supply hole 6b.

9 is a plunger chamber, which is a space surrounded by the upper surface of the plunger 6 and the plunger barrel 7; 10 is a fuel pump main body; 11 is a discharge valve; 12 is a discharge valve spring L; and 13 is an injection pipe.

14a is a plunger lead with a large inclination, which is a notch provided in the plunger 6 and is used in correspondence with the small diameter oil drain hole 8a.

Reference numeral 14b denotes a small-inclined plunger lead, which is a notch provided in the plunger 6. The notch has a smaller inclination than the large-inclined plunger lead 14a, and is used in correspondence with the large-diameter oil drain hole 8b.

In the case of a low load where the effective stroke is defined by the small oil drain hole 8a and the large inclined lead 14a, the beginning of the small inclined lead should be in the direction of the ball than the large inclined lead so that the large inclined oil drain hole 8b and the small inclined lead 14b do not come into contact with each other. is late.

The deviation in the crane direction is set so that at the reed switching point where the effective stroke begins to be defined by the large-wear E oil hole and the small-inclined lead, the small-scale oil drain hole and the large-inclined lead are also applied at the same time. Turtle 5 is a land for controlling oil supply and drain holes, and plunger 6
is located at the top of the.

The operation in the case of the above configuration will be described.

Here, the above-mentioned Fig. 11 shows the lead at low load (Fig. a).
Figure 12 shows the relative positions of the lead (figure a) and the oil supply and drain holes (figure b) at high loads. Figure 13a shows the relative positional relationship between the small light oil drain hole and the large lead at low load.
indicates the relative positional relationship between the large oil drain hole and the small inclined lead under high load.

When the load is low, if the plunger 6 rises due to the rotation of the fuel cam,
The large-diameter supply and oil competition holes 5b and 8b are closed by the land pipe 5 for controlling the oil supply and scale oil holes, and the area of the oil supply and oil drain holes before discharge is defined by the small oil supply and oil drain holes 5a and 8a.

If the plunger 6 further rises, "small diameter supply, scarlet oil hole 5"
a, 8a are gradually closed, and when the oil pressure in the plunger chamber 9 increases and becomes greater than the barrier pressure of the discharge valve spring 12, the discharge valve 11 is pushed up and the discharge of fuel is started. When the plunger 6 further rises, the large inclined lead turtle 4a engages the small diameter scale oil hole 8a, the small light oil drain hole 8a opens, the hydraulic pressure in the plunger chamber 9 decreases, and the discharge valve 1 closes. Dispensing ends.

At this time, after the large inclination lead 14a is applied to the 4.E oil hole 8a, the small inclination lead 14b is not applied to the Oyo oil drain hole 8b during the current period, and the area of the 9E oil hole is the small diameter oil drain hole 8a.
defined by. [I] When the load is high, the plunger 6 is rotated by the fuel injection amount control rack 4, so the oil hole control land 15 does not close the oil drain holes 5b and 8b, so the discharge The area of the front supply and oil drain holes is defined by the small diameter supply and oil drain holes 5a and 8a and the large rear supply and scale oil holes 5b and 8b.

The plunger 6 is raised to close the large oil feed and oil drain holes 5b and 8b, and the small oil feed and drain holes 5a and 8a, and discharge of fuel is started.

The plunger 6 further rises, the lead 14b engages the large oil drain hole 8b', the large diameter oil drain hole 8b opens, and the discharge ends. At this time, even if the small inclination lead 14b is caught in the large oil hole b, the large inclination lead 14a is not caught in the small diameter oil drain hole 8a, so fuel injection remains as before. The amount of fuel to be discharged is controlled by rotating the plunger 6 by the fuel injection amount control rack 4 and changing the relative position between the oil drain hole 8a and the plunger lead 14a or between the oil drain hole 8b and the plunger lead 14b. As a result, the effective stroke hH, hL as shown in FIG.
This is done by changing the .

Note that the Daihōe and scale oil holes are the same size as the conventional ones, meaning that they are larger than the small diameter feed and 9E oil holes.

In addition, the small slope IJ-N has the same slope as the conventional one,
This means that the slope is small compared to the large lead. The present invention as described above has the following effects.

Figure 14 is a diagram showing the difference in discharge characteristics depending on the rotation speed.
Figure 5 is a diagram showing the characteristics of the preflow amount with respect to changes in the oil supply hole area, Figure 16 is a diagram showing the characteristics of the afterflow amount with respect to changes in the oil drain hole area, and Figure 17 is a diagram showing the characteristics of the fuel injection amount with respect to changes in the rotation speed ( 6qf/6N)
The figure shows the fuel injection amount characteristics (6qf
/8Rc).

{1) In the case of low load, in order to use small-diameter oil supply and oil drain holes, the amount of preflow discharged before the plunger completely closes the oil supply and oil drain holes, and the amount of preflow discharged after the plunger lead hits the scarlet oil hole. The amount of afterflow discharged increases.

Compared to the conventional type, that is, Daijaku Kyu's scale oil hole, the amount of increase in the preflow amount and afterflow amount due to the area reduction varies depending on the rotation speed, and the pressure in the plunger chamber increases due to throttling at low speeds. The discharge speed from the small-diameter oil supply hole and small-diameter oil drain hole in the low-speed range shown by the thin line in the figure is higher than the discharge speed from the large-diameter oil supply hole and oil drain hole shown by the thick line, and the amount of increase is large, but on the other hand, at high speed Since the pressure in the discharge valve chamber becomes higher in the case, even if the pressure in the plunger chamber increases due to the throttle, the amount escaping from the oil hole 9E will increase. The amount of increase is not as large as in the case of a low-speed castle because it is not so large compared to the discharge speed by the oil hole.

Its characteristics are shown in FIG. 15 and FIG. 6. In Figure 5 of Turtle,
In Figure 6, the broken line shows the case of a small-diameter oil supply hole, and the solid line shows the case of a large-diameter oil drain hole. At low speeds, the preflow amount and the afterflow amount increase, so the shortcomings of the fuel injection amount characteristics in the low speed range are improved to the characteristics shown by the solid line in Figure 7 of the Army.

{2i In the case of high loads, a large diameter feed and a scarlet oil hole are used, so the injection characteristics are maintained as before.

'3} In low-load cases, the plunger lead with a large notch is used, so the amount of fuel injection per rack displacement increases, as shown by the solid line in Figure 18, and in high-load cases, the slope is small. Since a conventional plunger lead is used, conventional characteristics are maintained.

■ As a result, the stability of engine performance at low speeds and low loads is improved.

[Brief Description of the Drawings] Fig. 1 is a sectional view showing a conventional fuel injection pump, Fig. 2 is a perspective view showing a sectional view of the plunger lead and plunger barrel, and Fig. 3 is a diagram showing the plunger lead under load. An exploded view of the plunger and plunger barrel showing the relative positional relationship with the chick oil hole, Figure 5 is an edge diagram showing the fuel injection amount characteristics with respect to the pump rotation speed, and Figure 5 is a cross diagram showing the fuel injection amount characteristics with respect to the rack position. Fig. 6 is a diagram showing engine output torque with respect to rotation speed, Fig. 7 is an explanatory diagram showing a two-stage plunger lead, Fig. 8 is a sectional view showing a fuel injection pump according to an embodiment of the present invention, and Fig. 9 The diagram shows the plunger.
A perspective view showing the cross section of the plunger lead and the plunger barrel, Fig. 10 is an explanatory view showing the top surface of the plunger, the plunger barrel supply, and a cross section of the dummy oil hole, Fig. 1a is a developed view of the plunger neck, Fig. li b! The exploded view of the plunger barrel head showing the positions of the oil supply and oil drain holes, and the exploded view of the plunger barrel head shown in Figure 2, a and b, show the relative positions of the lead and thread joints under high load. Fig. 3a is a developed view showing the relative positional relationship between the small diameter oil drain hole and the large inclined lead under low load, and Fig. 3b is an expanded view showing the relative positional relationship between the large diameter dummy oil hole and the small inclined lead under high load. Figure 4 is an edge diagram showing the difference in discharge characteristics depending on the rotation speed, the superimposed diagram is a diagram showing the characteristics of the IJ flow amount with respect to changes in the area of the oil supply hole, and Figure 6 of the blade is a diagram showing the characteristics of the IJ flow rate with respect to changes in the area of the oil drain hole. A diagram showing the characteristics of the afterflow amount ``Figure 17 is a diagram showing the characteristics of the fuel injection amount with respect to changes in the rotation speed, Figure 8
The figure is a diagram showing fuel injection amount characteristics with respect to changes in rack position. Package...Fuel cam 2...Cam roller, 3...4 pump spring, 4...Rack for fuel injection amount control, 5a...・Small diameter oil supply hole 50...Oyoyo oil supply hole, 6...Plunger t 7...Plunger barrel, 8a...Small cost E oil hole ~ 8b...Large wear E oil hole, 9...Plunger chamber
Wataru crab...fuel pump body, 11 states...discharge valve, government 2...
Discharge valve spring, Tortoise 3...Injection pipe 14a...Large plunger lead, Tortoise 4b...Small tilt plunger lead, Force 5...Land for oil supply to oil drain hole control. Fig. 1 Fig. 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 13 Figure 12 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18

Claims (1)

[Claims] 1. A fuel injection pump having an oil supply and drain hole in a plunger barrel, and a plunger lead that controls the amount of fuel injection based on the relative positional relationship between the plunger barrel and the oil drain hole,
One set of large-diameter oil supply and oil drain holes provided on each of the plunger barrels, and one set of small-diameter oil supply and oil drain holes provided on each of the plunger barrels, each having a height corresponding to the large-diameter oil drain holes provided on each of the plunger barrels. a first plunger lead with a small inclination angle that controls the fuel injection amount under load; and a plunger lead formed with a larger inclination angle than the first plunger lead and corresponding to the small diameter oil drain hole for fuel injection under low load. A fuel injection pump characterized by comprising a second plunger lead for controlling the amount of oil, and a control land provided at the head of the plunger for controlling opening and closing of the large-diameter oil supply and drain holes.