JP2009041553A - Liquid leak measurement device for fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid leak measurement device capable of accurately, effectively and continuously measuring liquid leak quantity from a fuel injection valve. <P>SOLUTION: In the liquid leak measurement device using capillary, rise of liquid surface is fixed by external test liquid constant quantity supply means and control of connection speed, and test liquid remaining in the capillary is discharged and dried by an air blower means at every measurement to keep measurement conditions constant for every measurement with paying attention to a point that abrupt and unstable rise of liquid surface brought by capacity change due to connection of a work and a measurement part, and test liquid remaining in the capillary cause accuracy drop and efficiency drop of measurement result. Consequently, continuous measurement accuracy can be improved and high measurement efficiency can be provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an apparatus for measuring a liquid leakage amount when a fuel injection valve is closed.

2. Description of the Related Art Conventionally, as a means for measuring a liquid leakage of a fuel injection valve, as in Patent Document 1, a technique has been proposed in which a leaked test liquid is introduced into a thin tube and the amount of liquid level rise is measured.
In addition, as in Patent Document 2, by actively controlling the liquid level in the narrow tube, the liquid level instability that occurs when measurement is performed using the method of Patent Document 1 is attempted to improve efficiency. Has been proposed.
JP-A-5-66173 JP 2004-45249 A

However, in the measurement according to Patent Document 1, the liquid level rises due to the gravitational drop of the test liquid remaining on the inner wall of the narrow tube higher than the liquid level, and if this is being measured, it is determined as the amount of liquid leakage and accurate data is obtained. If it is not obtained and the test solution is lowered until the measurement is completed, the measurement efficiency is improved, but the measurement efficiency is lowered. In addition, an on-off valve for adjusting the liquid level is provided so as to be orthogonal to the midway of the passage from the object to be measured to the measuring capillary. Depending on the liquid filling state at this site, residual bubbles may enter the measuring capillary and rise. It becomes a factor to reduce the accuracy.

Further, according to the above-mentioned Patent Document 2, although the liquid level of the thin tube is stable during the measurement, the operation of canceling the volume change that occurs in the work clamping process at the start of the measurement cycle includes the clamp power source, the measurement thin tube level detection, the volume All of the change mechanisms need to be integrated and controlled, and the overall system is complex and expensive. In addition, since the operation of this volume change mechanism is directly and largely reflected on the level of the capillary tube, the operating characteristics and reliability of this mechanism are measured at the same time as the workpiece, making it impossible to confirm the test liquid filling state. With the long U-shaped liquid passage structure, the influence on the measurement results cannot be excluded.

The present invention has been made in view of the above-mentioned circumstances, eliminates the influence of the test liquid remaining on the inner wall of the thin tube on the measurement, demands high accuracy, and quickly stabilizes the liquid level without having a complicated mechanism. An object of the present invention is to provide a liquid leakage measuring device that can be obtained.

In the liquid leakage measuring apparatus according to claim 1 of the present invention, a fuel injection valve to be measured is connected to a jig, and a measurement preparation liquid is quantitatively supplied to the open upper portion. It has a multi-stage connection structure that rises and is connected to the measuring capillary. At this time, the amount of the measurement preparation liquid to be supplied is controlled to be quantitative, and the connection speed between the work holding part and the measurement thin tube is kept constant, so that the connection path is short and has a simple structure. The liquid level at the start is almost constant and quick around the liquid arrival height due to capillary action of the capillary, which is determined by the target liquid level reference height, i.e., test liquid properties and capillary properties, capillary inner diameter and inner wall wetness, etc. Can be raised. In addition, the test solution remaining on the inner wall of the thin tube is discharged by air blow performed every measurement, and the thin tube is dried, so that the measurement conditions are the same for each measurement and the continuous measurement accuracy can be improved.

As described above, according to the present invention, the test liquid remaining on the inner wall of the thin tube is discharged by air blow to eliminate the influence on the measurement and high accuracy is obtained, and the stability of the liquid level can be obtained quickly by the multistage connection structure.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic overall image of a liquid leakage measuring apparatus according to an embodiment of the present invention.
The fuel injection valve 1 to be measured is mounted on the setting jig 2 with the fuel injection port facing upward. Next, the air cylinder 3 is driven and pressed toward the connecting jig 4.
At this time, the injection port and the lower end of the liquid passage of the connecting jig 4 are sheeted by an O-ring (not shown). The above-described items 1 to 4 form the work holding unit 5.

Next, the test solution is supplied from the measurement preparation solution supply nozzle 6 to the open upper end surface of the connecting jig 4. When the liquid overflows from the upper end surface due to surface tension, the liquid is discharged through the drain pipe 7. This stage is shown in FIG.
Here, the amount of the test solution is adjusted in advance by a flow rate adjusting valve or a fixed discharge valve (not shown).

Next, the work holding unit 5 rises at a driving speed controlled by the actuator 8, and the test liquid supplied to the upper end surface of the connection jig 4 is applied to the lower end of the measurement thin tube 10 held by the measurement thin tube holder 9. Touch and begin to rise in capillaries by capillary action. Thereafter, the upper end surface of the connecting jig 4 is connected to the lower end surface of the measuring thin tube holder 9. Both end surfaces are sheeted by an O-ring (not shown). The actuator 8 may be used by controlling the speed of an air cylinder with a speed controller. However, in order to obtain speed stability, a reciprocating mechanism combining a ball screw and a motor or an electric cylinder may be used.

The process of increasing the liquid level and the significance of the measurement preparation liquid quantitative supply means and the multistage connection means will be described in detail below.

First, the liquid level is brought into contact with the lower end of the capillary tube to promote a relatively gradual liquid level rise by capillary action. The reason is that if the upper end surface of the connecting jig 4 and the lower end surface of the measuring thin tube holder 9 are connected at high speed, bubbles are generated in the liquid in the thin tube due to a sudden pressure change, and the measurement result is adversely affected. This is to prevent it.

At this stage, the liquid level does not need to rise to the height finally reached by capillary action. This is because the volume change due to the sheet of the O-ring after this further pushes up the liquid level. Therefore, at the end of the connection, the amount of liquid that enters the capillary tube is the total amount due to the capillary phenomenon and due to the volume change of the O-ring.

The supply amount of the measurement preparation liquid and the driving speed of the work holding unit 5 are set so that the total amount, that is, the final liquid level after the end of the connection is approximately the same as the natural final reached height determined only by capillary action. Is adjusted.

When the above operation is completed and the reference liquid level is obtained, the test liquid is supplied from the test liquid supply pipe 11 and measurement is started. The liquid surface position rising in the measurement thin tube 10 is detected by the CCD line camera 12 and calculated as a leak amount by the measurement calculation means 13. Here, a CCD line camera is used as the liquid level detection means, but it may be replaced with an optical displacement meter.

FIG. 3 shows the reference liquid level height Ho and the liquid level change amount ΔH during measurement.
The amount of leakage is, for example, mcc / min as a unit required by the measurement arithmetic unit 13 based on a value obtained by multiplying the liquid level change amount ΔH that has risen per unit time t seconds by the inner area of the measurement capillary 10. Calculated output. Here, in order to guarantee the measurement accuracy, the inner diameter dimension of the measurement capillary 10 to be used needs to be confirmed and guaranteed.

After the measurement is completed, the supply of the liquid from the test liquid supply pipe 11 is stopped, the work holding unit 5 and the fuel injection valve 1 are both lowered, the test liquid in the measurement thin tube 10 is discharged by the air blow nozzle 14, and the inner wall of the thin tube is dried. Is done. This air blow eliminates the effects of the gravity drop of the remaining liquid on the inner wall of the thin tube at the next measurement. This completes one cycle of measurement.

1 shows a schematic overview of a liquid leakage measuring apparatus according to an embodiment of the present invention. A state in which the measurement preparation liquid is quantitatively supplied by the measurement preparation liquid supply nozzle 6 onto the jig 4 to which the measurement object 1 is connected is shown. A reference liquid level height Ho and a liquid level change amount ΔH during measurement when the workpiece holding unit 5 is lifted and connected to the measurement thin tube 10 are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Set jig 3 Air cylinder 4 Connection jig 5 Work holding part 6 Measurement preparation liquid supply nozzle 7 Drain pipe 8 Actuator 9 Measurement thin tube holder 10 Measurement thin pipe 11 Test liquid supply pipe 12 CCD line camera 13 Measurement arithmetic device 14 Air blow nozzle Ho Reference liquid level height ΔH Liquid level change

Claims (1)

A fuel leakage measuring device for a fuel injection valve, more specifically,
An optical measuring means for measuring the amount of rise in the liquid level in the measuring capillary with a guaranteed inner diameter;
Calculation means for calculating the amount of liquid leakage based on the transition of the measured value,
A multi-stage connection structure in which a measurement object and a work holding part, a work holding part and the above-mentioned measurement capillary are connected in two stages,
A liquid quantitative supply means for quantitatively supplying the measurement preparation liquid in a pre-adjusted amount;
A constant speed driving means for driving the work holding portion at a speed adjusted in advance and connecting the work holding portion to the narrow tube;
An air blowing means for the thin tube for discharging the test solution remaining on the inner wall of the thin tube and drying the thin tube;
A liquid leakage measuring device comprising:

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