JPH035541B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle inspection method in which the cross-sectional shape of a spray stream of fuel oil or the like injected from a nozzle such as an internal combustion engine injection valve is compared with a reference shape to determine the quality of the nozzle.

2. Description of the Related Art In internal combustion engine fuel injection valves and the like, the shape of the spray flow is observed in order to judge whether the characteristics are good or bad. The conventional method in this case is to directly observe the spray flow using a strobe light emitting device or the like that emits light in synchronization with the fuel injection, and to inspect the quality of the spray flow based on the shape of the spray flow.

However, when using the conventional method as described above, it is only possible to observe the spray flow shape from the side.
Although it was possible to observe the shape of the fuel injection in the axial direction, the injection angle, the degree of breakage of the spray flow, the inclination, etc., it was not possible to inspect the shape of the spray flow in the cross-sectional direction.

The present invention has been made in view of the above, and an object of the present invention is to provide a nozzle inspection method capable of inspecting pass/fail by comparing the cross-sectional shape of the spray flow from the nozzle with a reference cross-sectional shape. .

The method of the present invention converts light from a light source into a film-like light screen consisting of parallel light rays so as to intersect the traveling direction of a spray flow from a nozzle, and a light screen portion including a cut surface of the light screen by the spray flow. is imaged by an image sensor, and the shape of the cut surface imaged by the image sensor is compared with a reference shape to inspect the quality of the nozzle.

The present invention will be explained below with reference to Examples.

FIG. 1 is a block diagram showing an embodiment to which the method of the present invention is applied. In this embodiment, a case will be explained using as an example a case where the quality of a fuel injection valve for an internal combustion engine having a nozzle orifice with a circular cross section is inspected. . Therefore, the reference shape in this example is circular.

1 is a fuel injection valve of a diesel engine. The fuel injection valve 1 is equipped with a lift sensor 2 consisting of a differential transformer or the like that detects the amount of movement of the needle valve, and is moved by the pressure of fuel oil sent from a fuel injection pump (not shown). The amount of movement of the needle valve is detected. 3 is a semiconductor laser or
The light source consists of a He-Ne laser or the like. Reference numeral 4 denotes an optical screen conversion device that converts the projected laser beam from the light source 3 into a film-like optical screen consisting of parallel rays, and includes, for example, a collimator lens 5 that receives the laser beam from the light source 3 and converts it into parallel rays, and a collimator. It is composed of a slit plate 6 into which the light projected from the lens 5 is incident. The optical screen converter 4 is installed so that the optical screen 7 projected from the optical screen converter 4 intersects the axis of the fuel injection valve 1. In this embodiment, the axis of the fuel injection valve 1 and the optical screen 7 are set to be perpendicular to each other.

On the other hand, 8 is an image sensor that images, through an optical system, a portion where the spray flow ejected from the fuel injection valve 1 crosses the optical screen 7, that is, a predetermined area portion including at least the cut surface of the light screen 7 caused by the spray flow. . The image sensor 8 is provided with, for example, 64 closely spaced photoelectric conversion elements, each of which constitutes one row of eight image pickup elements and one column of eight elements, which photoelectrically convert incident light. The image sensor 8 is further triggered by an external signal to sequentially scan the output of the photoelectric conversion element in the row direction starting from the first light receiving element in the first row and output it at a predetermined time interval, and also outputs a scanning pulse. A scanning circuit is provided to do this.

On the other hand, the image sensor 8 is provided so as to image the cut surface of the light screen 7 caused by the spray flow from a predetermined angular direction, and converts incident light with an elliptical cross section into light with a circular cross section and enters the image sensor 8. The cut surface is imaged through a cylindrical lens 9. Therefore, although the image sensor 8 images the cut surface from an oblique direction, the cylindrical lens 9 allows the image sensor 8 to image the shape of the cut surface as it is. The reason why the image is taken through the cylindrical lens 9 is that the cut surface cannot be imaged from the front by the image sensor 8, and even if the cross-sectional outline of the spray flow is circular, the This is because the sensor 8 is provided obliquely, so if the cut surface is directly imaged, it will appear as an ellipse, and this is to be corrected.

On the other hand, the output of the lift sensor 2 is supplied to a level comparator 10 to detect that the lift of the needle valve moved by the supply of fuel oil to the fuel injection valve 1 exceeds a predetermined value. The output of the level comparator 10 is supplied to a differentiation circuit 11, which differentiates the rising edge of the output signal of the level comparator 10. The output pulse of the differentiating circuit 11 is supplied to a waveform shaping circuit 12 for waveform shaping. The output pulse of the waveform shaping circuit 12 is supplied to the variable delay circuit 13, and after being delayed for a predetermined time, it is supplied as a trigger signal to the scanning circuit of the image sensor 8, and the output of the photoelectric conversion element of the image sensor 8 is sent to the first row. From then on, output is performed sequentially at the period of the scanning pulse.

Here, the delay time of the variable delay circuit 13 is such that after the needle valve reaches the set level of the level comparator 10 by supplying fuel oil at a constant pressure to the fuel injection valve 1, the spray flow injected from the fuel injection valve 1 is It is set to be longer than the time it takes for the light to reach the optical screen 7. Therefore, after the fuel oil is supplied to the fuel injection valve 1 and the spray flow becomes stable, the image sensor 8 outputs an image of the shape of the spray. Note that, as described above, the scanning order in this case is set to be performed sequentially from the first row.

The output signal from the photoelectric conversion element of the image sensor 8 is supplied to a level comparator 14. The output of level comparator 14 is supplied to counter 15 . On the other hand, the scanning pulse output from the scanning circuit of the image sensor 8 is supplied to the octal counter 16. Octal counter 16 output every 8 counts of the number of scan pulses
The output pulse is supplied to the delay circuit 17 and the write address counter 19. The delay time of the delay circuit 17 is set to compensate for the access time of the memory circuit 20, which will be described later, and the output pulse of the delay circuit 17 is supplied to the counter 15 as a reset pulse. The count value of the counter 15 is supplied to the memory circuit 20, and the write address counter 19
The data are sequentially stored in the addresses of the storage circuit 20 designated by the .

On the other hand, 21 is the standard cross-sectional shape A of the spray flow from the fuel injection valve 1 as shown in FIG.
64 squares B divided into rows and 8 columns overlap ×
This is a storage circuit in which a value obtained by counting the number of mark portions for each row is stored in advance from the first row to the eighth row. Since the cross-sectional shape of the nozzle injection hole of the fuel injection valve 1 in this embodiment is supposed to be circular,
The reference cross-sectional shape A is a circle.

The memory circuits 20 and 21 include a pulse generator 2
The output pulse of the read address counter 22 which counts the output pulses from 3 and specifies the read address of the memory circuits 20 and 21 is supplied;
The storage circuits 20 and 21 are arranged so that the stored contents at the same address designated by the output of the read address counter 22 are read out.

Reference numeral 24 denotes a comparison circuit to which the stored contents read from the storage devices 20 and 21 are respectively inputted, and which compares whether or not the quotient of both inputs is within a certain range, and generates an output when the quotient is outside the certain range.

In one embodiment of the present invention configured as described above, the fuel injection valve 1 is connected to the fuel injection pump (not shown).
By force-feeding fuel oil at a constant pressure, the needle valve of the fuel injection valve 1 moves, and fuel oil is sprayed from the fuel injection valve 1. The atomized stream of this atomization passes through the optical screen 7 and advances. The cross-sectional shape of the optical screen 7 due to this spray flow, that is, the cross-sectional shape of the spray flow at the position of the optical screen 7 is imaged by the image sensor 8 . This imaging output is sequentially scanned to the first row, second row, etc. by a scanning pulse output from the scanning circuit of the image sensor 8 triggered by the output of the delay circuit 13.
It is output to the level comparator 14. In this case, the needle valve of the fuel injection valve 1 is connected to the level comparator 10.
After the set delay time by the variable delay circuit 13 has elapsed from the time when the position corresponding to the set level has elapsed, the imaging output is taken out. Therefore, at the time when the imaging output of the image sensor 8 is taken out, the spray stream injected from the fuel injection valve 1 has reached the optical screen 7 and is in a stable state.

The imaging output of the image sensor 8 is output in synchronization with the period of the scanning pulse, is supplied to the level comparator 14, is binarized according to the set level of the level comparator 14, and is output. The high potential output from level comparator 14 is counted by counter 15. In this case, simultaneously with the supply of the imaging output to the level comparator 14, the scanning pulses are supplied to the octal counter 16 and counted. The octal counter 16 generates an output pulse every time it counts eight scanning pulses,
The counter 15 is reset by a pulse obtained by delaying this output pulse by the delay circuit 17. Therefore, the count value of the counter 15 is the same as that of the image sensor 8.
The number corresponds to the number of photoelectric conversion elements in each row that generate output corresponding to the cross-sectional shape of the spray flow detected by the photoelectric conversion elements. Note that a boundary value for determining a spray flow is determined by the set level of the level comparator 14.

On the other hand, the output pulse of the octal counter 16 is supplied to the write address counter 19, and the output of the write address counter 19 is incremented every time the output pulse of the octal counter 16 occurs, and the count value of the counter 15 is stored in the storage circuit 20. The addresses to be stored are sequentially designated, and the count value of the counter 15, that is, the number of photoelectric conversion elements of each row of the image sensor 8 that generates an output corresponding to the cross-sectional shape of the spray flow, is calculated from the first row. Sequentially up to the 8th line,
It will be stored in the memory circuit 20. Therefore, when all the outputs of the photoelectric conversion elements of the image sensor 8 are scanned, the memory circuit 20 stores data corresponding to the cross-sectional shape of the spray flow on the optical screen 7, as shown in FIG. It will be remembered.

Then, the pulse generator 23 generates an output pulse. The output pulses of the pulse generator 23 are counted by the read address counter 22, and the contents of the memory circuits 20 and 21 are sequentially read out starting from the first address and outputted to the comparator 24.
be compared. Here, the comparator 24 divides the input output data from the memory circuits 20 and 21, determines whether the quotient is within a certain range, and generates an output when it is outside the certain range. Therefore, when the cross-sectional shape of the spray flow on the optical screen 7 is not substantially similar to the reference shape corresponding to the data stored in advance in the memory circuit 21, a signal is output from the comparator 23, and the fuel injection It is possible to determine whether the valve is good or bad.

In the above-described embodiment of the present invention, the nozzle hole of the fuel injection valve has a circular cross-section, but the same applies to other cross-sectional shapes.

In addition, in the embodiment of the present invention described above, in order to prevent the optical screen conversion device 4 and the cylindrical lens 9 from being contaminated by the fuel spray flow from the fuel injection valve 1, the screen conversion device 4 and the spray flow are Maintenance is also easy if an air curtain is formed between the cylindrical lens 9 and the spray stream.

In the above-described embodiment of the present invention, the case where the quality of the fuel injection valve 1 for an internal combustion engine is determined is taken as an example, but the same applies to other nozzles.

As explained above, according to the present invention, the optical screen is provided so as to intersect with the axis of the nozzle, the shape of the cut surface of the optical screen due to the spray flow from the nozzle is imaged by the image sensor, and the spray flow imaged by the image sensor is Since the quality of the nozzle is inspected by comparing the cross-sectional shape with the reference shape, it is possible to determine the quality of the nozzle more accurately than the conventional inspection by observing the spray flow from the side.

Also, there is no scattering of the spray stream,
In addition, the spray flow cross section can be detected in a non-contact manner.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment to which the method of the present invention is applied. FIG. 2 is a diagram for explaining the storage contents of the memory circuit in the above embodiment. 1...Fuel injection valve, 2...Lift sensor, 3...
... light source, 4 ... light screen conversion device, 7 ... light screen, 8 ... image sensor, 9 ... cylindrical lens, 10 and 14 ... level comparator, 13
and 17...Delay circuit, 15 and 16...Counter, 19...Write address counter, 2
0 and 21...Storage circuit, 22...Read address counter, 24...Comparator.

Claims (1)

[Claims] 1. Convert the light from the light source into a film-like light screen consisting of parallel light rays so as to intersect the traveling direction of the spray flow from the nozzle, and use the light screen portion including the cut surface of the light screen by the spray flow as an image sensor. and comparing the shape of the cut surface imaged by the image sensor with a reference shape,
A nozzle inspection method characterized by inspecting the quality of a nozzle.