JPH04284162A - Adjustment of initial lift qnantity in two-stage valve-opening pressure fuel injection nozzle - Google Patents

Abstract

PURPOSE:To reduce the dispersion of the initial fuel injection quantity between fuel injection nozzles. CONSTITUTION:A cylinder device 3 supplies the fuel having the pressure higher than the initial valve opening pressure and lower than the main valve opening pressure into a two-stage valve-opening pressure fuel injection nozzle 2. As for the supply quantity of the fuel supplied into the two-stage valve-opening pressure fuel injection nozzle 2 from the cylinder device 3, the position of the large diameter piston part 5a of the cylinder device 3 is detected by a position sensor 7, and a calculating means 18 performs calculation on the basis of the detection signal. The calculated supply quantity is recorded by a recorder 19. Then, the initial lift quantity is adjusted so that the supply quantity recorded by the recorder 19 is set within the range of allowable values.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the initial lift amount in a two-stage valve-opening pressure fuel injection nozzle.

0002

[Prior Art] In a two-stage valve-opening pressure fuel injection nozzle (hereinafter sometimes simply referred to as a fuel injection nozzle), when the fuel pressure exceeds the initial valve opening pressure, the needle valve initially lifts and the initial injection is performed. When the fuel pressure rises further and exceeds the main valve opening pressure, the needle valve is fully lifted and main injection is performed. When adjusting the initial lift amount of the needle valve in such a two-stage valve opening pressure fuel injection nozzle, the initial lift amount of the needle valve is actually measured and adjusted so that this measured value falls within the specified tolerance. (Refer to Japanese Unexamined Patent Publication No. 59-46364).

0003

However, when the initial lift amount of the needle valve is controlled by a permissible value, there is a problem that large variations occur in the initial injection amount among the fuel injection nozzles.

[0004] When this point was investigated, it was found that the cause was as follows. That is, the relationship between the lift amount of the needle valve and the fuel injection amount is different between the fuel injection nozzles A and B, as shown in FIG. 4, because there are manufacturing errors of the injection holes in each fuel injection nozzle. In this case, in a range where the lift amount is approximately the initial lift amount, the rate of increase in the fuel injection amount relative to the lift amount is large. For this reason, the initial lift amount is determined by the vertical tolerance Lmax, Lmin.
When managed, the maximum value Qmax and minimum value Q of the fuel injection amount
This results in a large difference between min and min. As a result, large variations occurred in the initial injection amount between each fuel injection nozzle.

The present invention was made based on the above findings, and an object of the present invention is to provide a method for adjusting the initial lift amount in a two-stage valve-opening pressure fuel injection nozzle that can suppress variations in the initial injection amount to a small level. do.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an initial lift of the needle valve when the pressure of the fuel pumped from the fuel injection pump becomes equal to or higher than the initial valve opening pressure.
When the fuel pressure exceeds the main valve opening pressure, the needle valve fully lifts. When adjusting the initial lift amount of the two-stage valve opening pressure fuel injection nozzle, the needle valve fully lifts when the fuel pressure exceeds the initial valve opening pressure. It is characterized by supplying fuel having a pressure lower than the valve opening pressure and adjusting the initial lift amount of the needle valve so that the amount of fuel supplied per unit time is within a predetermined range. be.

[0007]

[Operation] Fuel having a pressure higher than the initial valve opening pressure and lower than the main valve opening pressure is supplied to the fuel injection nozzle, and the amount supplied per unit time is measured. Then, the lift amount of the needle valve is adjusted so that the supply amount per unit time falls within a predetermined range.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 shows a fuel supply device 1 used when carrying out the adjustment method of the present invention, and this fuel supply device 1 supplies fuel at a predetermined pressure to a two-stage valve-open pressure fuel injection nozzle 2. It is structured as follows.

In FIG. 1, reference numeral 3 indicates a cylinder device. This cylinder device 3 consists of a cylinder 4 and a piston 5, and the cylinder 4 has a large diameter cylinder hole 4a.
and a small diameter cylinder hole 4b. A large-diameter piston portion 5a of the piston 5 is slidably provided in the large-diameter cylinder hole 4a, and a small-diameter piston portion 5b of the piston 5 is slidably provided in the small-diameter cylinder hole 4b. The large diameter piston part 5a and the small diameter piston part 5b are integrally connected by a rod 5c.

The interior of the cylinder 4 is divided into three chambers by a piston 5. That is, the pressurized fuel introduction chamber 6 is divided by the large diameter cylinder hole 4a and the large diameter piston part 5a, and the large diameter cylinder hole 4a, the small diameter cylinder hole 4b, the large diameter piston part 5a, and the small diameter piston part 5b.
The return fuel introduction chamber 7 is defined by the small-diameter cylinder hole 4b and the small-diameter piston portion 5b, and the fuel pressurizing chamber 8 is defined by the small-diameter cylinder hole 4b and the small-diameter piston portion 5b.

The pressurized fuel introduction chamber 6, the return fuel introduction chamber 7, and the fuel pressurization chamber 8 are connected to the pump 10 by a directional control valve 9.
and the fuel tank 11. That is, when the directional control valve 9 is in the illustrated state, the pressurized fuel introduction chamber 6 is connected to the fuel tank 11, and the return fuel introduction chamber 7 and the fuel pressurization chamber 8 are connected to the pump 10. When the directional control valve 9 is switched from the illustrated state, the pressurized fuel introduction chamber 6 is connected to the pump 10, and the return fuel introduction chamber 7 and the fuel pressurization chamber 8 are connected to the fuel tank 11. However, a check valve 12 is installed immediately before the fuel pressurizing chamber 8.
is installed, the fuel in the fuel pressurizing chamber 8 will not leak into the fuel tank 11.

In the above configuration, when the pressurized fuel supply chamber 6 is connected to the pump 10, the piston 5 is moved from the large diameter cylinder hole 4a side to the small diameter cylinder hole 4b side by the fuel introduced into the pressurized fuel introduction chamber 6. be forced to move. Then, the fuel in the fuel pressurizing chamber 8 is pressurized to a high pressure based on the difference in area between the large diameter piston part 5a and the small diameter piston part 5b. The pressurized fuel is force-fed to the fuel injection nozzle 2. In this case, the pressure of the fuel fed to the fuel injection nozzle 2 can be adjusted by adjusting the pressure of the fuel supplied from the pump 10 to the pressurized fuel introduction chamber 6 using the pressure regulating valve 13.
Can be adjusted. Normally, the pressure of the fuel supplied to the fuel return nozzle 2 is higher than the initial valve opening pressure of the fuel injection nozzle 2 and lower than the main valve opening pressure, for example, 10% lower than the initial valve opening pressure.
The pressure is adjusted to be about Kg/cm2 higher. Note that the pressure of the fuel supplied to the fuel injection nozzle 2 is measured by a pressure gauge P.

When the directional control valve 9 is switched from the above state, fuel is supplied from the pump 10 to the return fuel introduction chamber 7 and the fuel pressurizing chamber 8. Therefore, the piston 5 returns from the small diameter cylinder hole 4b side toward the large diameter piston hole 4a side. As a result, the fuel in the pressurized fuel introduction chamber 6 is returned to the fuel tank 11.

Furthermore, between the pressurized fuel introduction chamber 6 and the directional control valve 9, there is a throttle 14a for suppressing the pulsation of the fuel supplied from the pump 10 to the pressurized fuel introduction chamber 6, and a A hydraulic block 14 is installed in which a check valve 14b for allowing fuel to flow out from the chamber 6 into the fuel tank 11 without resistance is installed in parallel. A hydraulic block 15 similar to the hydraulic block 14 and having a throttle 15a and a check valve 15b is also installed between the return fuel introduction chamber 7 and the directional switching valve 9.

Further, the cylinder device 3 is provided with a position sensor 17 made of a magnetic scale or the like along the large diameter cylinder hole 4a. This position sensor 17 is
This is for detecting the position of the large diameter piston portion 5a, and its output is output to the calculation means 18. Arithmetic means 18
calculates the supply amount Q of fuel supplied from the cylinder device 3 to the fuel injection nozzle N based on the output signal from the position sensor 17. That is, if the positions of the large-diameter piston portion 5a before and after the passage of unit time are respectively A1 and A2, and the cross-sectional area of the small-diameter cylinder hole 4b is S, then the fuel supply amount Q per unit time is S・(A2-A1). become. The supply amount Q calculated by the calculating means 18 is stored in the recorder 19.
is output to. The recorder 19 records the supply amount Q and graphs it as shown in FIG.

Next, a case will be described in which the initial lift amount of the fuel injection nozzle 2 is adjusted using the fuel supply device 1 having the above configuration. The directional control valve 9 is switched from the illustrated state to supply fuel from the pump 10 to the pressurized fuel introduction chamber 6. As a result, the fuel in the fuel pressurizing chamber 8 is pressurized and the fuel is supplied to the fuel injection nozzle 2.

Since the pressure of the fuel supplied to the fuel injection nozzle 2 is higher than the initial valve opening pressure and lower than the main valve opening pressure, the needle valve (not shown) of the fuel injection nozzle 2 is initially lifted. At the same time, the fuel is injected from the fuel injection nozzle 2. In this case, the amount of injection injected from the fuel injection nozzle 2 is constant because the pressure of the supplied fuel is constant and the lift amount of the needle valve is constant (initial lift amount). Therefore, the amount of fuel supplied to the fuel injection nozzle 2 (the amount of fuel supplied per unit time) also becomes constant, and is recorded by the recorder 19 as shown in A, B, and C in FIG.

If the supply amount Q per unit time is between the preset upper and lower limits, as shown in FIG. be done. As shown in FIG. 2B, when the supply amount is larger than the upper limit value, the initial lift amount of the fuel injection nozzle 2 is corrected to be smaller. Then, the above-mentioned supply amount measurement is performed again. This is repeated until the supply amount Q falls between the upper limit value and the lower limit value. When the supply amount is smaller than the lower limit value as shown in FIG. 2C, the initial lift amount of the fuel injection nozzle 2 is corrected to be larger. After that, the process is the same as in case A above.

As is well known, the initial lift amount is adjusted by changing the thickness of a shim or the like that regulates the initial lift amount.

As described above, by adjusting the initial lift amount based on the supply amount Q, variations in the initial injection amount in each fuel injection nozzle 2 can be reduced. In other words, the supply amount Q per unit time and the actual fuel injection amount are:
If the mutual pressures are equal, they will be almost the same. Therefore, when the initial lift amount of the needle valve is adjusted by the supply amount Q, as shown in FIG. can. Note that the upper limit and lower limit of the supply amount are determined by experiments, and are determined to be such values that variations in the initial injection amount will not be a problem as long as they are within these ranges.

The present invention is not limited to the above embodiments, but can be modified as appropriate without departing from the gist thereof. For example, instead of the fuel supply device 1 in the embodiment described above, fuel may be supplied to the fuel injection nozzle 2 by another supply device. In addition, in the above embodiment, the pressure of the fuel supplied to the fuel injection nozzle 2 is maintained constant during the measurement period of the supply amount, but if it is difficult to do so, for example, the pressure of the fuel supplied to the fuel injection nozzle 2 is maintained constant. The pressure may be gradually increased, and it may be detected whether the supply amount at a predetermined pressure falls between an upper limit value and a lower limit value.

[0022]

As explained above, according to the method for adjusting the initial lift amount of the present invention, fuel having a pressure higher than the initial valve opening pressure and lower than the main injection valve opening pressure is supplied to the fuel injection nozzle, and the unit Since the initial lift amount of the needle valve is adjusted so that the amount supplied per hour is within a predetermined range, it has the effect of suppressing variations in the initial injection amount at each fuel injection nozzle. can get.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a fuel supply device for implementing the adjustment method of the present invention.

FIG. 2 is a diagram showing the relationship between measurement time and the amount of fuel supplied per unit time when fuel at a constant pressure is supplied to the fuel injection nozzle in the apparatus shown in FIG.

FIG. 3 is a diagram showing the relationship between the lift amount of the needle valve and the amount of fuel supplied per unit time when fuel is supplied to the fuel injection nozzle with the apparatus shown in FIG. 1;

FIG. 4 is a diagram showing the relationship between the lift amount of the needle valve and the fuel injection amount.

[Explanation of symbols]

1 Fuel supply device 2 Fuel injection nozzle 3 Cylinder device 18 Arithmetic means 19 Recorder

Claims (1)

[Claims] Claim 1: A two-stage opening system in which the needle valve initially lifts when the pressure of fuel pumped from the fuel injection pump exceeds the initial valve opening pressure, and fully lifts when the fuel pressure exceeds the main valve opening pressure. When adjusting the initial lift amount of the valve-pressure fuel injection nozzle, fuel having a pressure higher than the initial valve-opening pressure and lower than the main valve-opening pressure is supplied to the two-stage valve-opening pressure fuel injection nozzle. A method for adjusting an initial lift amount in a two-stage open valve pressure fuel injection nozzle, the method comprising adjusting the initial lift amount of a needle valve so that the supply amount is within a predetermined range.