JPH0245652A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To achieve the reduction of noise and NOx by setting the primary injection stroke and the min. sectional area of a fuel leak part to each arbitrary value. CONSTITUTION:A parallel groove 35 is formed on the outer peripheral surface 25 of the head part 24 of a plunger 14, and the min. sectional area Amin of the fuel leak part which communicates to the parallel groove 35 and the plunger top surface can be adjusted, and the primary injection stroke can be adjusted. Therefore, the two-stage injection characteristic and the initial stage injection characteristic in an arbitrary operation region can be improved by setting the min. sectional area Amin of the fuel leak part and the primary injection stroke to each arbitrary value, and the reduction of noise and NOx can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection pump for an internal combustion engine.

(Prior art and its problems) In general, in diesel engines, the ignition delay period of the fuel spray is longer during low-speed operation than during high-speed operation. Therefore, during low-speed operation, combustion occurs rapidly after ignition, resulting in There is a problem in that the rate of pressure rise within the combustion chamber becomes large, which causes large combustion noise.

In order to suppress such combustion noise, considering the cause of its occurrence, it is necessary to suppress the rate of pressure rise in the cylinder due to combustion.
In other words, it is effective to cause the mixture to burn slowly in the cylinder, and to achieve this, for example, the method disclosed in Japanese Utility Model Application Publication No. 59-30555 is proposed.
A technology that employs a staged injection method is known.

By the way, recently, low noise and low NOx in any driving range have been introduced.
Although there is a demand for a fuel injection pump that can achieve nitrogen oxide (nitrogen oxide) conversion, a fuel injection pump that can perform such two-stage injection has not yet been known.

Patent application No. 62-29256 as prior art related to this case
There is No. 7.

(Objective of the Invention) An object of the present invention is to provide a fuel injection pump that can achieve low noise and low NOx in any operating range.

(Structure of the Invention) (1) Technical Means The present invention makes it possible to pressurize and force-feed fuel by reciprocating a plunger within a barrel. The fuel injection amount is adjusted by forming a communicating reed in the form of a diagonal groove and appropriately rotating the plunger and the barrel relative to each other to adjust the communication timing between the reed and the boat on the barrel side. In the fuel injection pump, a parallel groove is formed on the circumferential surface of the head A of the plunger so that it can communicate with the boat on the barrel side within a relative rotation range of the barrel and the plunger,
The minimum cross-sectional area A min of the fuel leak part that communicates this parallel groove with the top surface of the plunger is set to be adjustable, so that the plunger head closes the boat on the barrel side and the parallel groove communicates with the boat on the barrel side. The primary injection stroke S1 in which the plunger slides when not in use is adjustable, and the primary injection stroke St and the minimum cross-sectional area A of the fuel leak part are adjusted.
This fuel injection pump is characterized in that the two-stage injection characteristic and the short initial injection rate control can be exhibited in any operating range by appropriately setting the value n.

(2) Effect primary injection stroke S1 and fuel leak portion minimum cross-sectional area A
By setting 1n to an arbitrary value, two-stage injection characteristics and initial injection rate control type characteristics can be exhibited in an arbitrary operating range, and low noise and NOx can be achieved.

(Implementation Project) (1) First Embodiment FIG. 1 shows a fuel injection pump for a diesel engine according to a first embodiment of the present invention.
0 is a pump body with an integrated take-up flange; 11 is a barrel fitted and fixed in the pump body 10;
A horizontally long rectangular slit boat 12 (barrel side boat) extending in the circumferential direction is formed on one side of the barrel 1, that is, the left side in the figure.

A plunger insertion hole 13 is formed in the axial center of the barrel 11 so as to communicate with the slit boat 12. A plunger 14 is fitted into the plunger insertion hole 13 so as to be slidable within a relative rotation range, and the plunger 14 is reciprocated in the axial direction by the spring force of the plunger spring 15 and the cam action of the fuel cam 16. By moving the engine, the fuel sucked into the high pressure chamber 18 formed on the top surface 17 is pressurized, and the fuel is delivered to the injector (not shown) provided in each cylinder of the engine (not shown) via the delivery valve 2o. It is designed to be fed under pressure.

In addition, in FIG. 1, the reference numeral 21 is a plunger rotating wheel that is attached to the plunger 14 so as to be able to engage with it in the circumferential direction. By appropriately pushing and pulling the rack gear 23, the rack gear 23 is relatively rotated within the barrel 11,
It is adapted to carry out a predetermined metering action. That is, as shown in FIGS. 2 and 3, on the outer circumferential surface 25 of the head 24 of the plunger 14, there is approximately one oblique groove-shaped lower lead 26 (lead) spaced appropriately from the top surface 17. It is also formed around the circumference. Further, this lower lead 26 is connected to the plunger 1 through a fuel relief hole 27 extending in the axial direction of the plunger.
4 is communicated with the top surface 17 of 4. Note that 28 in FIG. 1 is a supply pipe through which fuel flows to the slit boat 12.

Therefore, by rotating the plunger insertion hole 13 relative to the barrel 11, the relative communication timing between the lower lead 26 of the plunger 14 and the slit boat 12 of the barrel 11 is changed, and the closing period of the slit port 12 is changed. The adjustment adjusts the fuel injection plate.

As shown in FIGS. 4 and 5, the delivery valve 20 includes a valve body 30, a valve seat 31, and a delivery spring 3.
2 (FIG. 1), the valve body 30 is biased against the valve seat 31 to open and close.
As shown in A sectional view), an annular collar 33 is integrally formed, and has a function of sucking back fuel by the amount of sucking back stroke 7111 in FIG. 4 when the delivery valve 20 is closed (fuel injection end timing). It is equipped with Note that the collar 33 of this embodiment is not provided with the conventionally known Angleich cut.

A metering mechanism consisting of a combination of such a slit boat 12 and a lower lead 26 communicating with the slit boat 12 is conventionally known, but this embodiment is not limited to this. It also has the ability to exhibit two-stage injection characteristics and initial injection rate control characteristics in any operating range. Although this adjustable injection characteristic is not variable once set, it can be set to any operating range depending on the characteristics required by the engine.

In FIG. 2, a substantially horizontal parallel groove 35 is cut into the head 24 of the plunger 14 by two points from the outer periphery 25 (FIG. 3). The lead part lead 26 is cut by zl. This parallel groove 35 is formed at a height B at a position below the top surface 17 by a dimension Y. In addition, a throttle passage 36 opens at the center of the parallel groove 35 to E (FIG. 3), and the minimum cross-sectional area Am1n of the fuel drain part of the throttle passage 36 is as follows.
A*In, -B x E - (1). In FIG. 2, reference numeral 50 is a fuel cut lead.

The throttle passage 36 is not limited to the case shown in Fig. 2, but also shown in Figs. 2a and 3.
It is also possible to form a throttle passage as shown in Figures 2a, 2b and 3b. That is, Fig. 2a, Fig. 3
When the vertical groove 40 that communicates with both the parallel groove 35 and the lower lead 26 is formed as shown in FIG. Next, as shown in FIGS. 2b and 3b, the parallel groove 35
When a is formed in a continuous annular shape over the entire circumference of the plunger 14, the vertical groove 40 and the parallel groove 35a communicate on both sides, and the minimum cross-sectional area of the fuel leak part of the throttle passage 30b is A min
, becomes Am1n, -2·B X E −·−(1°).

Next, the positional relationship between the parallel groove 35 and the slit boat 12 is such that the top surface 17 and the upper edge of the slit boat 12 are aligned, and are spaced apart by a primary injection stroke Sl, which will be described in detail later.
Secondary injection stroke S with plunger 14 raised
It separates the 2. The size of the slit boat 12 is width b,
The height is set to a. Therefore, the primary injection stroke S1 becomes 5L-Ya (2). Note that the slit boat 12 is not limited to the oval shape with the left and right end portions shown in the drawing having arcuate shapes, but may be rectangular with a rectangular cross section.

Once the minimum cross-sectional area A win of the fuel leak part and the primary injection stroke Sl shown in equations (1) and (2) above are set, they cannot be changed, but they can be adjusted according to the fuel injection characteristics required by the engine. It can be set to any value,
As will be described in detail later, the minimum cross-sectional area A1n of the fuel leak part
By changing the value of the primary injection stroke Sl, it is possible to exhibit two-stage injection characteristics or to exhibit initial injection rate control type characteristics in an arbitrary operating range.

The lower lead 26 is inclined at an angle θL at a position lowered by X from the rr4 surface, and is cut from the outer periphery 25 at an appropriate depth, and the fuel escape hole 27 and the lower lead 26 are connected to the communication hole 37. It communicates with

Note that in the case of this embodiment in which the delivery valve 20 is not provided with the aforementioned Angleich cut, there is no injection delay (load timer function) due to the Angleich cut.

Barrel 11 with said slit port 12 and parallel groove 35
In FIG. 7 showing a two-stage injection stroke by the plunger 14 with a
The lower edge of the slit boat 12 coincides with the lower edge of the slit boat 12, and in this state, even if the plunger 14 rises, the fuel in the high pressure chamber 18 is not compressed.

Next, in (b), when the top surface 17 and the working edge of the slit boat 12 coincide, the slit boat 12 is closed by the plunger 14, and as the plunger 14 rises, the high pressure chamber 1
8 starts to be compressed, and the primary injection I1 starts from θ1 of (X) showing the injection pattern. This primary injection 11 is injected during the primary injection stroke Sl until the parallel groove 35 communicates with the slit boat 12, and in (c) the parallel groove 35
When the upper edge and the lower edge of the slit boat 12 match, the slit boat 12 passes through the fuel relief hole 27 and the throttle passage 36.
The high pressure chamber 18 communicates with the high pressure chamber 18, the compression process of the fuel in the high pressure chamber 18 is once completed, and the primary injection I is completed at θ2 in (X).

In the state of (d), the slit boat 12 and the high pressure chamber 18 are communicating through the parallel groove 35 and the fuel relief hole 27, so even if the plunger 14 rises, the fuel in the high pressure chamber 18 is not compressed, and (X) Fuel injection stops in the △θ° section.

Eventually, at (e), the lower edge of the parallel groove 35 and the slit boat 1
When the upper edges of 2 coincide, the high pressure chamber 18 is sealed again.
Secondary injection 12 starts at θ3 of (X). This secondary injection I
2 continues over the section S2, and at (r), the lower lead 26 and the lower edge of the slit boat 12 coincide, and the slit boat 1 passes through the lower lead 26 and the communication hole 37 (FIG. 2).
2 and the high pressure chamber 18 communicate with each other, that is, at θ4 of (X) 2
Next injection I2 ends.

Therefore, 80 and △θ′ of (X) are Δθ=SI
+a+B −(3) Δθ゛゛a+B ...(4) It becomes.

As described above, the primary injection If is generated by the primary injection stroke S1, and the rotational speed at which the two-stage injection characteristic (X) begins to occur changes as described below.

In the two-stage injection stroke shown in Figure 7, the primary injection stroke S
1 and the minimum cross-sectional area of the fuel leak part Am1n, which are arbitrarily set, will be explained with reference to FIG. 8, which is a graph of engine speed N (rpm) - output W.

In FIG. 8(a), where the primary injection stroke S1 is large and the minimum cross-sectional area A min of the fuel leak part is large, the primary injection stroke S1 is large, so two-stage injection is performed even in the low rotation range where the plunger speed is slow. This results in a two-stage injection pattern over the entire area. The primary injection stroke S1 in FIG. 8(b) is large, and the minimum cross-sectional area of the fuel leak part A 1n,
When is small, a two-stage injection pattern is generated in the low rotation range of region DI, and an initial injection rate control type characteristic in which primary injection I1 and secondary injection I2 are continuous is exhibited by the throttling action in the medium and high speed region of region D2. do.

When the primary injection stroke S1 in FIG. 8(C) is small and the minimum cross-sectional area A1n of the fuel leak part is large,
Because the plunger speed is slow in the low rotation range of region D3, primary injection I1 does not occur, and as the rotation speed N increases, 1
The next injection amount Q1 increases, and a two-stage injection pattern occurs in region D4. When the primary injection stroke S1 in FIG. 8(d) is small and the minimum cross-sectional area A1n of the fuel leak part is small, the first stage injection is performed in the low speed range of region D5, and the second stage injection is performed in the middle speed region of region D6. The initial injection rate control type characteristics are exhibited in the high-speed injection region D7.

Therefore, by arbitrarily setting the primary injection stroke S1 and the minimum cross-sectional area A sin of the fuel leak part, two-stage injection characteristics or initial injection rate control type characteristics can be achieved in any rotation speed range and load range. , low noise, low NOx
(nitrogen oxides).

(2) In the first embodiment described above, the two-stage injection characteristic or the initial injection rate control type characteristic can be exhibited in any operating range as shown in Fig. 8, but the primary injection stroke S[, Minimum cross-sectional area of fuel leak part A
Although the injection characteristics cannot be changed once m1n is set to a certain value, in this second embodiment, the primary injection 11 and the secondary injection I2 can be made variable so as to exhibit the optimal two-stage injection characteristics over the entire range. The points are distinctive. 9 and subsequent drawings showing the barrel 11 of the second embodiment are the same as FIG. 1. The parts indicated by No. 1 indicate the same or equivalent parts.

In FIG. 9, a window hole 51 is formed in the barrel 11, leaving a portion of the connecting wall 50 (FIG. 1O) open. A sleeve 52 is fitted into this window hole 51. Sleeve 52
A protrusion 53 projects from the upper surface of the barrel 11, and the protrusion 53 fits into a recess 54 of the barrel 11 so as to be slidable up and down. Therefore, the oblong slit port 5 is located between the protrusion 53 and the four parts 54.
5 (barrel side boat) is formed so that the height X can be freely adjusted. The sleeve 52 is formed with a cylindrical surface 56 having the same diameter as the plunger insertion hole 13 of the barrel 11.

The plunger 14 that fits into the barrel 11 in FIG.
As shown in Figure 1, the fuel suction lead 6 is placed above the parallel groove 35.
0 is the formation. The fuel intake lead 60 is cut to a depth of Z2 (FIG. 12), and an intake port 61 communicating with the fuel escape hole 27 is opened. In FIG. 13, which is a sectional view taken along line a-a in FIG. 9, an eccentric pin 63 is fitted into the four parts 62 of the sleeve 52, and the pin 63 is operated by means such as hydraulic pressure, electronic control, and negative intake pressure. By sleeve 52
can be raised and lowered freely. Note that the technology for making the sleeve 52 freely move up and down is disclosed in Utility Model Publication in 1983 by the applicant.
It is described in detail in No.-3418.

FIG. 13 shows the state at low speed when the sleeve 52 is sliding upward, and FIG. 16 shows the two-stage injection stroke in this state.

When the slit port 55 and fuel suction lead 60 are in communication as shown in FIG. 16(a), the chamber 18 passes from the slit port 55 through the suction port 61 and reaches the state shown in FIG. 16(b).
Fuel flows into the prestroke Lp, and the prestroke Lp is constant over the entire operating range. Parallel grooves 35 in FIGS. 16(b) to 16(C)
The stroke until the slit boat 55 communicates with the
The next injection stroke is S1. At low speed in Figure 15,
Since the sleeve 52 has risen the most, the primary injection stroke S1 is the longest.

In FIG. 16(d), the fuel in the chamber 18 is not compressed and the parallel groove 35 is closed.FIGS. 16(c) to 16(r)
The fuel is pumped again in the secondary injection stroke S2 until the lower lead 26 and the slit boat 55 communicate with each other. This secondary injection stroke S2 changes with rotation of the plunger 14 due to rack operation.

At high speed as shown in FIG. 15, the sleeve 52 is lowered by the pin 63, and the height X of the slit port 55 extends downward and becomes higher. The injection stroke in this state is as shown in FIG. 14, and the primary injection stroke Sl is shortened by the downward extension of the slit port 55. On the other hand, in the case of the same rack position, the secondary injection stroke S2 becomes shorter.

In the second embodiment described above, as the engine speed increases, the sleeve 52 descends and the primary injection stroke Sl
The secondary injection stroke S2 changes i■.

For example, when the sleeve 52 moves down by ΔX at the equal rack position, the primary injection stroke S1 and the secondary injection stroke S2 will each decrease by Δχ. However, the primary injection stroke St changes only by the displacement of the sleeve 52, but the secondary injection stroke S2 continuously changes by both the displacement of the sleeve 52 and the rack operation.

Since the prelift Lp is always constant, the primary injection start timing is also constant.

Both the primary injection timing and the secondary injection timing are constant in each rotation speed range and each load range.

Regarding the injection pattern, the interval Δθ'' between the primary injection 1 and the secondary injection 12 can be adjusted by changing the height X- of the slit boat 55 and the width B of the upper 8 groove 35.

Furthermore, by changing the minimum cross-sectional area A1n of the fuel leak part, two-stage injection characteristics can be achieved, and an initial stage where primary injection 11 and secondary injection (2) are continuous and primary injection 11 is controlled. It can be switched to exhibit injection rate control type characteristics.

If the minimum cross-sectional area Am1n of the fuel leak part is large,
As shown in Fig. 17, an optimal two-stage injection pattern occurs in the entire operating range, and the minimum cross-sectional area of the fuel leak part A min in Fig. 18 is achieved.
, is small, an initial injection rate control pattern occurs in the high-speed region Da.

Therefore, since the sleeve 52 is made movable by the pin 63, stable two-stage injection or initial injection rate control characteristics can be exhibited over the entire range, and low noise and low NOX (nitrogen oxides) can be achieved.

The slit boat 55 is not limited to the case shown in FIG. 9, but may be formed between the stepped portion 70 on the barrel 11 side and the stepped portion 71 on the sleeve 52 side as shown in FIG. 19. 20, the upper surface 73 of the window hole 51
A slit boat 5 is inserted between the step portion 74 on the sleeve 52 side and
5 may be formed.

(Effect of the invention) As explained above, in the fuel injection pump according to the present invention,
A parallel groove 35 is formed on the outer circumferential surface of the head of the plunger 14 so that it can communicate with the boat on the barrel side within the relative rotation range of the barrel 11 and the plunger 4, and this parallel groove 35 communicates with the top surface of the plunger to prevent fuel leakage. Minimum cross-sectional area A ll1in
is set to be adjustable, and the primary injection stroke S1 in which the plunger slides in a state where the plunger head closes the boat on the barrel side and the parallel groove 35 does not communicate with the boat on the barrel side is adjusted ML function. By setting the primary injection stroke S1 and the minimum cross-sectional area of the fuel leak part As1n to arbitrary values, two-stage injection characteristics and initial injection rate control characteristics can be exhibited in any operating range, resulting in low noise. and low N
oxidation can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention, FIG. 2 is a side view of a plunger, FIGS. is the second
The view in the direction of the ■ arrow, Figures 3a and 3b are structural diagrams showing other embodiments of the plunger, Figures 4, 5 and 6 are structural diagrams of the delivery valve, and Figure 7 is a schematic diagram of the structure of the delivery valve. Stroke diagram showing the stage injection stroke, Figure 8 is a graph of rotation speed vs. output, Figure 9 is a graph of rotation speed vs. output.
Figure 10 is a side view of a barrel according to a second embodiment of the invention;
The figure is a sectional view taken along the line X-X in FIG. 9, FIG. 11 is a side view of the plunger of the second embodiment, FIG. 12 is a view taken along arrow a in FIG. 11, and FIG. 13 is a-a in FIG. 9. Cross-sectional view, Figure 14 shows 2 at high speed.
A stroke diagram showing the stage injection stroke, Fig. 15 is a structural diagram at low speed, and Fig. 16 is a stroke diagram showing the two stage injection stroke at low speed.
7 and 18 are rotation speed-output graphs, and FIGS. 19 and 20 are structural diagrams showing another embodiment. 10...
Pump body, 11... Barrel, 12... Slit boat, 14... Plunger, 20... Delivery valve, 26... Lower lead, 27... Fuel relief hole, 3
5...Parallel groove, 36...Vertical groove, 52...Sleeve, 63...Bin patent applicant Yanmar Diesel Co., Ltd. Figure 20

Claims (1)

[Claims] (1) Fuel can be pressurized and pumped by reciprocating the plunger within the barrel, and an oblique groove-shaped lead communicating with the top surface of the plunger is formed on the outer peripheral surface of the head of the plunger, In a fuel injection pump that adjusts the amount of fuel injection by appropriately rotating the plunger and the barrel relative to each other and adjusting the communication timing between the lead and the port on the barrel side, the outer peripheral surface of the head of the plunger A parallel groove that can communicate with the port on the barrel side is formed in the relative rotation range of the barrel and the plunger, and a minimum cross-sectional area Amin. is set to be adjustable, and the primary injection stroke S1 in which the plunger slides in a state where the plunger head closes the port on the barrel side and the parallel groove does not communicate with the port on the barrel side is set to be adjustable; This primary injection stroke S1 and the minimum cross-sectional area of the fuel leak part Ami
n. 2 in any operating range by setting appropriately.
A fuel injection pump characterized by exhibiting staged injection characteristics and initial injection rate control characteristics.