JPH04356257A - Dew condensation detector - Google Patents

Abstract

PURPOSE:To prevent contaminant particles such as dust and nicotine from attaching to the bedewing sensor portion of a bedewing detector which detects dew drops in air based on changes in the resistance value between electrodes by providing an electrostatic type filter in the air circulating passage of opposite electrode portions. CONSTITUTION:An electrode-interspace type bedewing detector D for e.g. controlling the defroster of a car air conditioner is fixed at the upper end of the inner face portion of windshield glass and comprises a main body board 10 made by a printed circuit board 11, a first cover member 20 surrounding the board 10 and forming an air introducing space, and a second cover member 30 which is fitted with the first member 20; an electrostatic type filter 40 is disposed in the upper portion of the detector D from the air introducing portion to the opposite electrode portions (bedewing sensor portion)12 of the printed circuit board 11. The electrostatic type filter 40 comprises an electrostatic electrode 43 of a wide area and good ventilation formed by machining of an aluminium thin plate into a mesh and glass fiber layers 41, 42 disposed respectively on the upper and lower faces of the electrode 43.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an electrode gap type dew condensation detector, and is designed to prevent contaminant particles such as dust, cigarette smoke, cleaner particles, etc. from adhering to the dew condensation sensor portion of the dew condensation detector. The present invention relates to the structure of a dew condensation detector.

0002

2. Description of the Related Art Hitherto, dew condensation detectors have been widely used, which have an electrode gap type dew condensation sensor and detect the condensation state of an object to be detected from a change in resistance value between opposing electrodes. For example, Japanese Unexamined Patent Publication No. 198551/1983 discloses a similar structure of a dew condensation detector provided on the inner surface of a front windshield for use in defroster control of an automobile air conditioner.

[0003] Usually, this type of dew condensation detector is fixed to the surface of an object to be detected, such as a window glass surface, as described above.
The sensor section is often provided in an open state to the external atmosphere around the object to be detected.

0004

[Problems to be Solved by the Invention] As mentioned above, in the conventional electrode gap type dew condensation detector, the sensor part (counter electrode part) is provided in an open state to the external atmosphere. Contaminant particles such as dust containing cigarette smoke in the external atmosphere tend to adhere to the surface of the sensor section. Therefore,
This causes a change in the resistance value between the opposing electrodes, causing a problem in that the preset dew condensation detector erroneously detects a low dew condensation level that is different from the target dew condensation level on the detection target surface that should be detected.

For example, as described in the above-mentioned prior art publication, when a dew condensation detector is provided on the inner surface of the front windshield of an automobile, smoke particles when a passenger smokes or the front windshield When the oil film was cleaned on the inside surface of the glass, particles from the cleaner adhered between the electrodes of the condensation sensor and caused conduction between the electrodes, causing the condensation detector to falsely detect condensation and causing the air conditioner to operate unnecessarily. A problem occurs.

For example, the graph in FIG. 9 shows the results of measuring the change in the resistance value of the dew condensation sensor S due to cigarette smoke with respect to the condensation level on the inner surface of the front windshield. Very slight condensation on the window glass surface, then condensation level L3/L4
is a state in which there is some dew condensation on the front windshield surface, and is the dew condensation level at which the air conditioner should be operated in the defrost mode based on the detection signal from the dew condensation detector. Further, at dew condensation levels L5 and L6, there is significant dew condensation on the front windshield surface. Of the five types of dew condensation sensors measured here, four types of dew condensation sensors are shown in Figure 8, for example.
Using the automatic smoking device 100 shown in FIG. 1, the target dew condensation sensor S is fixed in the 12-liter container 100a, one cigarette C is smoked in 24 hours by the automatic smoking part 100b, and the smoke is transferred into the container 100a. The number of cigarettes displayed in FIG. 9 indicates the number of cigarettes smoked by the automatic smoking device 100. Further, the smoke equivalent to 10 cigarettes discharged into the container 100a in this manner corresponds to the cigarette smoke discharged from the vehicle interior in one year.

Looking at the results, as shown in FIG. 9, the resistance value of the dew condensation sensor S changes depending on the degree of contamination. For example, when the dew condensation resistance value of the dew condensation sensor S is set to 0.5 MΩ, When the sensor S is not contaminated with cigarette smoke, condensation is detected for the first time at condensation level L3, but if the condensation sensor S is contaminated with smoke from 8 to 13 cigarettes, almost no condensation will occur on the front windshield surface. When the condensation level L2 is not present, it is mistakenly detected as dew condensation, and the air conditioner is operated in defrost mode. On the other hand, if the detection resistance value of the dew condensation sensor S is set to a high value of 0.7 MΩ, for example, so that condensation is detected only at condensation levels L3 and L4 even if the dew condensation sensor S is contaminated with cigarette smoke, This time, when the dew condensation sensor S is not contaminated by cigarette smoke, a problem arises in that the dew condensation state on the front windshield surface cannot be detected unless the front windshield surface reaches a large condensation state close to the condensation level L6. .

An object of the present invention is to provide a dew condensation detector that does not cause the above-mentioned malfunctions by preventing contaminant particles from adhering to the sensor section of the dew condensation detector itself.

[0009]

[Means for solving the problem] Claims 1 and 2 of the present application
In order to achieve each of the above objects, the described inventions are configured with the following problem-solving means.

(1) Structure of the dew condensation detector according to the invention as claimed in claim 1 The dew condensation detector according to the invention as claimed in claim 1 is based on the change in resistance value between electrodes facing each other with a predetermined gap therebetween. In an electrode gap type dew condensation detector for detecting dew condensation in the air, an electrostatic filter is provided in an air flow path of the counter electrode section.

(2) Structure of the dew condensation detector according to the invention set forth in claim 2 The dew condensation detector according to the invention set forth in claim 2 is based on a change in resistance value between electrodes facing each other with a predetermined gap maintained between them. In an electrode gap type dew condensation detector that detects a state of dew condensation in the air, a blower fan is provided upstream of the air flow path to the counter electrode portion, and an electrostatic filter is provided between the blower fan and the electrode portion. It is composed of

0012

[Function] As a result of each of the dew condensation detectors of the invention recited in claims 1 and 2 of the present application being constructed as described above, the following functions are achieved corresponding to each of the configurations.

(1) Function of the dew condensation detector according to the invention set forth in claim 1 The dew condensation detector according to the invention set forth in claim 1 is first provided with electrodes serving as dew condensation sensors that face each other with a predetermined gap therebetween. , a dew condensation state corresponding to a change in humidity in the air is detected based on a change in resistance value between the opposing electrodes.

[0014] On the other hand, an electrostatic filter is provided in the air flow path of the electrode section provided with the counter electrode, and uses static electricity to adsorb dust such as cigarette smoke in the air supplied to the counter electrode. Make sure to remove it.

(2) Function of the dew condensation detector according to the invention claimed in claim 2 In the dew condensation detector according to the invention claimed in claim 2, like the dew condensation detector according to the invention claimed in claim 1, first, a predetermined gap is established between each other. It is equipped with opposing electrodes that face each other, and detects a dew condensation state corresponding to a change in humidity in the air based on a change in resistance value between the opposing electrodes.

On the other hand, since a blower fan is provided upstream of the air flow path to the counter electrode portion and an electrostatic filter is provided between the blower fan and the electrode portion, the blower fan improves efficiency. Specifically, a large amount of ambient air, such as vehicle interior air, is supplied to the counter electrode section to detect the dew condensation state with good response.

Furthermore, at the time of detection, an electrostatic filter is provided downstream of the blower fan to eliminate dust such as cigarette smoke in the atmospheric air supplied to the counter electrode section, which can cause false detection. Since it is reliably removed by electrostatic adsorption, the state of dew condensation can always be accurately detected.

[0018]

Therefore, according to the dew condensation detector of the present invention, detection due to intrusion of dust can be reliably prevented, and reliability of dew condensation detection accuracy can be ensured over a long period of time.

[0019]

【Example】

(1) First Embodiment A first embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 6.

The dew condensation detector of this embodiment is constructed by applying the present invention to, for example, a dew condensation detector for controlling a defroster of an automobile air conditioner.

First, in FIGS. 1 and 2, reference numeral D indicates a dew condensation detector D in this embodiment. It is being Then, O representing the dew condensation state of the front windshield W from the dew condensation detector D
The N signal and the OFF signal indicating the dew condensation release (or non-condensation) state are input to the control unit of the vehicle air conditioner (not shown), and based on the ON/OFF signal from the condensation detector D, the defroster outlet shown in the figure is activated. The operation of starting and stopping the blowing of air conditioning air from 2 is automatically controlled as desired.

As shown in detail in FIG. 3, the dew condensation detector D includes a main body board 10 made of a printed circuit board 11 and a first cover member that surrounds the main body board 10 and forms a predetermined air introduction space. 20 and the first cover member 20
and a second cover member 30 which is fitted onto the second cover member 30.

The resistance value of the main body board 10 is reduced due to the rectangular printed circuit board 11 fixed to the inner surface of the front windshield W and the adhesion of conductive particles such as moisture particles mounted on the printed circuit board 11. It is composed of a counter electrode section (electrode gap type dew condensation sensor section) 12 and various detection circuit elements 13 and 14.

The counter electrode section 12 is composed of positive and negative electrodes 12a and 12b facing each other with a predetermined gap therebetween.

The first cover member 20 is composed of a short cylindrical member with a rectangular cross section corresponding to the rectangular outer circumference of the printed circuit board 11, and is fixed to the outer circumference of the printed circuit board 11 at its base end. and a pair of four openings 21, 21, 22, 22 on the upper end side thereof.
is formed by cutting out a slit.

Furthermore, the second cover member 30 has a rectangular top plate portion 3 which is crowned and fixed to the upper end side of the first cover member 20 and whose overall width is larger than the cross section of the first cover member 20 by a predetermined width.
1, and side plate portions 32, 32, 3 extending from the outer peripheral edge of the top plate portion 31 toward the main body substrate 10, substantially parallel to the first cover member 20, and halfway up the side wall of the first cover member 20.
3 and 33.

Further, as shown in FIG. 4, the electrostatic filter 40 is provided at least from the air introduction section to above the entire counter electrode section (condensation sensor section) 12 of the printed circuit board 11. For example, a thin aluminum plate is processed into a mesh shape to form a wide-area electrostatic electrode 43 with good ventilation, and glass fiber layers 41 and 42 are disposed on both upper and lower surfaces of the electrostatic electrode 43.

By configuring the dew condensation detector D as described above, atmospheric air near the front windshield W is introduced through the four openings 21, 21, 22, 22, and the opposing electrodes 12a, 12b are The state of dew condensation can be detected from the change in the resistance value between the two, and finally the state of dew condensation on the front windshield W portion can be detected. In this case, contaminant particles such as cigarette smoke particles in the introduced atmospheric air can be shielded to a certain extent by the baffle structure of the side wall of the second cover member 30, so that the counter electrode part (dew condensation) can be shielded to a certain extent. It is possible to prevent contamination of the sensing surface of the sensor section 12, and in particular, in this embodiment, the air circulation section from the openings 21, 21, 22, 22 to the positive and negative opposing electrodes 12a, 12b of the dew condensation sensor section is prevented from being contaminated. Since the electrostatic filter 40 with a large area is installed, dust such as cigarette smoke in the atmospheric air introduced into the positive and negative opposing electrodes 12a and 12b is reliably removed, which is different from the conventional method. Such false detections are reliably prevented.

Now, in the case where the electrostatic filter 40 is provided as described above, the detection responsiveness of the dew condensation sensor S to cigarette contamination is improved compared to, for example, a case where a similar configuration is realized using a separate activated carbon filter. When compared and examined, the graphs shown in FIGS. 5 and 6 are obtained.

Comparing the measured data in the graphs of FIG. 5 and FIG. 6, firstly, in the case of FIG. 6 using the activated carbon filter, it is possible to fall within the target detection accuracy range A regardless of the number of cigarettes smoked. On the other hand, if the electrostatic filter 40 is adopted as in this embodiment, all the measured numbers of cigarettes smoked can fall within the target range A.

Therefore, according to the configuration of the dew condensation detector D of this embodiment, erroneous detection of dew condensation due to the influence of dust in the air inside the vehicle is reliably prevented, and the reliability of detection accuracy is maintained over a long period of time. It becomes possible to secure the following.

As a result, the degree of freedom in designing the aperture structure and aperture ratio of the apertures 21, 21, 22, 22 for introducing atmospheric air of the dew condensation detector D, for example, is improved, and they are not necessarily installed on the window glass surface. This also expands the range of choices for installing the detector.

(2) Second Embodiment Next, FIG. 7 shows the configuration of a dew condensation detector according to a second embodiment of the present invention.

In the dew condensation detector of this embodiment, for example, the detector main body is a box-shaped casing 50, and the main body casing 5
The vertical wall portion on one end side of the casing 50 is formed by a printed circuit board 11 having a counter electrode portion 12 similar to that of the first embodiment, while an opening 52 for introducing atmospheric air is provided on the other end side of the casing 50. is opened to form an air flow path 53 that reaches the printed circuit board 11 from the opening 52.

Further, on the downstream side of the air flow passage 53, air exhaust ports 54a and 54b are formed in the vertical direction of the printed circuit board 11, while on the upstream side, a blower fan 55 is provided, To increase the introduction efficiency of atmospheric air.

In this state, the blower fan 55 and the air exhaust ports 54a, 54b of the air flow passage 53
An electrostatic filter 40 similar to that of the first embodiment is disposed between the air and the air in the vertical direction perpendicular to the air flow, and is constructed as shown in the figure.

According to this configuration of the dew condensation detector D,
In addition to the effect of improving the detection accuracy by the electrostatic filter 40, the effect of the blower fan 55 greatly improves the efficiency of introducing outside air, resulting in the advantage of particularly high responsiveness when detecting dew condensation.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the mounting position of a dew condensation detector according to a first embodiment of the present invention on a vehicle.

FIG. 2 is a side view showing how the dew condensation detector is attached to the front windshield of a vehicle.

FIG. 3 is an exploded perspective view of the main body of the dew condensation detector.

FIG. 4 is a sectional view of the main body of the dew condensation detector.

FIG. 5 is a graph of measurement data showing the detection response of the same dew condensation detector.

FIG. 6 is a measured data graph showing the detection response when an activated carbon filter is used in place of the electrostatic filter of the dew condensation detector of this embodiment.

FIG. 7 is a sectional view showing the configuration of a dew condensation detector main body according to a second embodiment of the present invention.

FIG. 8 is a schematic diagram showing the configuration of a contamination level testing device for measuring the detection characteristics of a conventional dew condensation detector.

FIG. 9 is a graph showing measurement results of detection characteristics of a conventional dew condensation detector using the apparatus shown in FIG. 8;

[Explanation of symbols]

1 is an automobile, 10 is a main body board, 11 is a printed circuit board, 12 is a counter electrode section, 12a and 12b are positive and negative counter electrodes,
20 is a first cover member, 21 and 22 are openings, 30 is a second cover member, 40 is an electrostatic filter, and 55 is a blower fan.

Claims (2)

[Claims] 1. In an electrode gap type dew condensation detector that detects a state of dew condensation in the air based on a change in resistance value between electrodes that face each other with a predetermined gap therebetween, an air flow path in the opposing electrode section is provided. A dew condensation detector characterized by being equipped with an electrostatic filter. 2. In an electrode gap type dew condensation detector that detects a state of dew condensation in the air based on a change in resistance value between electrodes facing each other with a predetermined gap therebetween, air circulation to the opposing electrode portion is provided. A dew condensation detector characterized in that a blower fan is provided upstream of the street, and an electrostatic filter is provided between the blower fan and the electrode section.