JPH0426422B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a device for detecting the degree of contamination of an air filter that collects minute dust from the air.

[Prior art]

Conventionally, the degree of dirt on an air filter has been determined by measuring the pressure loss, since pressure difference occurs across the air filter surface due to clogging of the air filter. In recent years, several methods have been proposed for detecting the level of dirt using light. For example, JP-A-57-
There are known examples such as 42480, but these are all
This is based on light transmittance, in which a light emitting part is provided on one side of the air filter and a light receiving part is provided on the other side so that light passes through the filter, and the degree of contamination is measured from the amount of transmitted light. Further, the light emitting section light receiving section is a fixed detection device attached to the vicinity of the filter. This detection device can measure accurately when the filter is small, but it cannot be used if a light emitting element, light receiving element, or mirror cannot be installed on both sides of the filter. The disadvantage is that a large number of detection devices must be installed.

In addition, there are light emitting and light receiving elements on both sides of the filter surface.
When measuring dirt on an arbitrary filter surface while placing a mirror and moving the detection device, there is a drawback that the device becomes large-scale in order to maintain airtightness before and after the air filter.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art, and to detect and move the dirt from one side of the air filter by measuring the scattered light from the air filter surface instead of transmitting the light through the air filter. Our aim is to provide equipment that can do this.

[Key points of the invention]

This invention utilizes the fact that the reflectance of glass fibers changes when microscopic dust in the air is attached to and collected on the glass fiber network of the air filter. , so that light is applied from one side of the air filter to capture the reflected light from the glass fiber surface, and a small filter with the same fabrication surface as the air filter to be measured is used for compensation in order to accurately capture the reflected light. It is.

That is, the air filter dirt detection device according to the present invention is a device that detects dirt on the filter by irradiating light onto the air filter to be measured and converting the received light energy into a current voltage, the device includes a light emitting element directed toward the filter to be measured; A measuring element consisting of a light receiving element, a compensation filter equivalent to the filter to be measured, and a compensation element consisting of a light emitting element and a light receiving element directed toward the compensation filter are located on one side of the air filter to be measured and are movable. The apparatus is equipped with a calculation means for simultaneously taking in detection signals from the measuring element and the compensation element and calculating a ratio thereof, and means for displaying the dirt determination of the filter to be measured based on the signal ratio of the calculation means. It is prepared.

According to this configuration, the reflected light of the filter to be measured depends on its dirt, so the amount of scattered light increases with the degree of dirt, and the amount of light received by the light receiving element decreases. On the other hand, by using a clean compensation filter, reflected light can be received by the compensation element at the same time, and this detection signal corresponds to a clean state. In the device of the invention, the detection section is moved along the filter to be measured, receives reflected light from the filter to be measured and the compensation filter in the same environment, and calculates the ratio of the detection signals. Since the signal ratio is continuously detected and the value of the signal ratio changes depending on the degree of dirt, dirt can be easily determined.

[Embodiments of the invention]

FIG. 1 is a system diagram of one embodiment of the present invention, and shows a detection end 22 and a compensation filter 2, each of which has a light-emitting element 3 and a light-receiving element 5 that move along a guide 21 at a constant distance from the air filter 1 to be measured. A compensation unit 9 having a light emitting element 4, a light receiving element 6, an amplifier 8 for amplifying the voltage converted from the light receiving element, a light generation source 7 and an optical fiber 10 for supplying light to the light emitting element are built in, and a moving means 18 is installed. It consists of a detection section 11 with a An amplifier 13 and a digital converter 1 provide an analog voltage signal from this detection section depending on the signal transmission distance.
4, the calculation unit 15 calculates, for example, the ratio ri (=Vi/Vo) between the compensation voltage Vo and the measured voltage Vi, and stores it in the storage device 16. After the measurement is completed,
The stored values are displayed on the cathode ray tube 19 or the list 20 by a display, for example, by changing the symbols in ascending order of the values to display the difference in dirt. Furthermore, when a metal surface of the measurement film is detected, ri becomes an extremely large value and can be determined as an abnormal value, which allows for instructions to move the measurement point or to delete the measurement value. The detection end 22 and the light-receiving and light-emitting elements of the compensator 9 are fixed to the filter surface in a direction in which the angle of incidence and the angle of reflection are approximately equal, so as not to shift due to vibration.

[Modifications and application examples of the invention]

In FIG. 1, the detection section 11 is provided with a moving means 18 and moved on a guide 21 to sequentially measure the dirt on the filter.
10498 may be loaded on an automatic filter changing device known in the art.

It is now possible to use the measurement and measurement result signal as a start signal for an automatic exchanger, and to determine the order in which filters should be replaced.In equipment with a large number of filters, it is possible to replace them in the order of their degree of contamination, instead of replacing them all at once. .

According to this embodiment, in two spaces separated by an air filter, dirt can be detected only from one side without installing a detector or sensor on the opposite side, and an extra through hole is required in the filter partition wall. There is no need to worry about air bypassing dirt.

When there are a plurality of air filters, it is possible to sequentially measure dirt by moving the detection device of the present invention on one side.

Furthermore, by converting the compensating filter into one manufactured in the same manner as the measuring filter before starting the measurement, it is possible to prevent changes in measurement accuracy due to differences in the material and structure of the filter.

[Effects of the Invention] As explained above, the present invention provides an apparatus for detecting contamination of the filter by irradiating light onto the air filter to be measured and converting the received light energy into current and voltage. A measuring element consisting of an element and a light-receiving element, a compensation filter equivalent to the filter to be measured, and a compensation element consisting of a light-emitting element and a light-receiving element directed toward the compensation filter are positioned and movable on one side of the air filter to be measured. It has a calculation means which is mounted on the detection part and which calculates the ratio of the detection signals from the measuring element and the compensation element while simultaneously taking in the detection signals, and the dirt on the ratio measuring filter is determined and displayed based on the signal ratio by this calculation means. Since the structure is equipped with a means for adjusting the filter, it is possible to receive the scattered light from the filter to be measured that changes depending on the degree of contamination in the same environment as the filter to be measured, and at the same time to receive the scattered light from the compensating filter that is not dirty. Incorporating both detection devices,
Since the dirt determination can be made by continuously calculating the ratio of both signals, an excellent effect can be obtained in that dirt determination can be made immediately and continuously while moving the ratio measuring filter over a wide range.

[Brief explanation of drawings]

FIG. 1 is a system diagram of one embodiment of the air filter dirt detection device according to the present invention. 1...Air filter to be measured, 2...Compensation small filter, 3...Light emitting element, 4...Light emitting element, 5
. . . Light receiving element, 6 . . . Light receiving element, 7 .
3...Amplifier, 14...Digital converter, 15...
...Arithmetic unit, 16...Storage device, 17...Display device,
18... Transportation means, 19... Braun tube, 20...
...Printer, 21...Guide, 22...Detection end.

Claims (1)

[Claims] 1. In a device that irradiates light onto an air filter to be measured and converts received light energy into current and voltage to detect dirt on the filter, a measuring element comprising a light emitting element and a light receiving element directed toward the filter to be measured;
A compensation filter equivalent to the filter to be measured, and a compensation element consisting of a light emitting element and a light receiving element directed toward the compensation filter are mounted on a movable detection unit located on one side of the air filter to be measured, The present invention is characterized by comprising a calculation means for simultaneously taking in the detection signals from the measuring element and the compensation element and calculating a ratio thereof, and means for displaying the dirt determination of the ratio measuring filter based on the signal ratio obtained by the calculation means. Air filter dirt detection device.