JPH0511453Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a tilt sensor that can be mounted on, for example, agricultural machinery or construction machinery to detect the slope of agricultural machinery under harsh outdoor environmental conditions. Regarding sensors.

[Conventional technology]

2. Description of the Related Art There is a tilt sensor that is mounted on a machine used under severe environmental conditions, such as a tractor, to detect the tilt of the tractor.

This inclination sensor is used to, for example, sound a buzzer or the like to issue an alarm when the inclination of the tractor exceeds a certain value, thereby preventing the tractor from tipping over.

Among the above-mentioned tilt sensors, a capacitive tilt sensor that electrically detects the tilt of a tractor or the like is known. The applicant has proposed a capacitive tilt sensor that can accurately detect the tilt of a tractor or the like even under severe environmental conditions (Utility Application No. 61-27187).

Figure 4 is a diagram showing a capacitance type tilt sensor of a previously proposed invention; Figure A is a cross-sectional view of this tilt sensor, and Figure B is a cross-sectional view taken along line b of Figure A. It is a diagram.

In the figure, 1 is a printed wiring board made of a heat-resistant material such as a glass cloth-based epoxy resin laminate. A differential electrode 3 consisting of a pair of fan-shaped electrode plates 3a and 3b is formed on this printed circuit board 1. 2 is a common electrode plate with appropriate rigidity;
Reference characters a and 2b are the legs of this common electrode plate 2. This common electrode plate 2 has legs 2a and 2b connected to the printed circuit board 1.
It is inserted into a hole (not shown) formed in and fixed by soldering, so that it is held parallel to the differential electrode 3 at a constant interval. Reference numeral 6 denotes a case made of a plastic material having appropriate flexibility, and together with the printed circuit board 1 constitutes a container. Reference numeral 4a denotes an injection port for injecting a dielectric liquid 5 such as silicone oil into a container consisting of a case 6 and a printed circuit board 1, and a rubber stopper 4 is inserted into this injection port 4a.

Differential electrode 3, common electrode 2, and case 6
are formed substantially concentrically, and their opposing surfaces are parallel to each other. The dielectric liquid 5 is at a level of approximately 1/2 of the effective volume within the container consisting of the case 6 and the printed circuit board 1 from the injection port 4a;
That is, as shown in FIG. 4B, it is filled up to the level of the center line D of the concentric circles of the differential electrodes 3 and the like. Thereafter, the rubber stopper 4 is inserted into the injection port 4a. Then, the space between the rubber stopper 4 and the case 6 is sealed with an adhesive to prevent dust and the like from entering the container.

Reference numeral 7 designates an electrostatic shield plate provided on both sides of the printed circuit board 1 to block external influences, 8 a housing, and 8a a lid.

FIG. 3 is a diagram showing an example of a circuit that obtains a voltage depending on the tilt angle.

In the figure, OSC is an oscillator mounted on a printed circuit board 1. Common electrode 2, dielectric liquid 5
and a capacitor C1 consisting of a sector-shaped electrode 3a;
A capacitor C2 consisting of a common electrode 2, a dielectric liquid 5 and a sector electrode 3b is connected to an oscillator OSC, respectively.
becomes an oscillating element.

Signals of oscillation frequencies corresponding to the capacitance values of the capacitors C1 and C2 are respectively supplied to frequency-voltage conversion circuits CV1 and CV2 as capacitance-voltage conversion circuits mounted on the printed circuit board 1. Then, voltages corresponding to the oscillation frequencies of the capacitors C1 and C2 are supplied from the frequency-voltage conversion circuits CV1 and CV2 to the differential amplifier circuit DA. Then, capacitor C1 and capacitor C2
A voltage DV corresponding to the difference in oscillation frequency between the two capacitors C1 and C2, that is, the difference in capacitance value between the capacitors C1 and C2, is obtained at the output side of the differential amplifier DA. This voltage DV is
A control circuit (not shown) is supplied. And this control circuit controls this voltage DV
When the angle of inclination of the tractor or the like exceeds a predetermined value, a buzzer (not shown) is activated to issue an alarm.

The capacitive tilt sensor configured as described above can withstand severe temperature changes ranging from, for example, -40°C to +80°C due to the expansion and contraction of the gas inside the container consisting of the case 6 and the printed circuit board 1. Pressure fluctuations are absorbed by the expansion and contraction of the case 6 and the rubber stopper 4, and there is almost no fluctuation in the electrode spacing.

[Problem that the invention attempts to solve]

As mentioned above, in the conventional capacitive tilt sensor, the rubber stopper 4 is closed during use of the tilt sensor.
If dust or the like gets into the container into which the dielectric liquid is being injected through the gap between the injection port 4a and the injection port 4a, there is a risk that an error will occur in the detection of the inclination. Inlet 4
It is necessary to seal the rubber stopper 4 with adhesive after inserting it into the hole A, which has the drawback of complicating the operation. Furthermore, if the dielectric liquid adheres to the vicinity of the injection port 4a, there is a drawback that the sealing of the rubber stopper 4 with the adhesive becomes incomplete.

[Means for solving problems]

This invention has a printed wiring board 9 as a part thereof, a thin wall portion 10a, and a dielectric liquid 5.
a case 10 in which the dielectric liquid 5 is sealed, and an injection port 9 provided in the case 10 for injecting the dielectric liquid 5.
In a capacitive tilt sensor consisting of a capacitance detection electrode 2 and 3 provided in a case 10, an injection port 9a is provided on a printed wiring board 9, and during soldering work of the printed wiring board 9. The injection port 9a is sealed with solder.

[Effect]

In this way, in the present invention, an injection port 9a for injecting dielectric liquid into the case 10 is provided in the printed wiring board 9, and this injection port 9a is sealed with solder during soldering work of the printed wiring board 9. As a result, there is no need to use a rubber stopper like in the past, and there is no need for adhesive, reducing material costs. Moreover, the injection port 9a can be sealed at the same time as the soldering of the printed wiring board 9. Since the work can be carried out, work efficiency is improved.

〔Example〕

FIG. 1 is a sectional view of one embodiment of this invention, and FIG. 2 is an explanatory view of the main part of the example shown in FIG. In the figure, the differences from the example in FIG. 4 are the printed wiring board and the case, and the other parts are the same and are given the same reference numerals.

In the figure, 9 is a printed wiring board made of a heat-resistant material such as a glass cloth base epoxy resin laminate. A pair of fan-shaped electrodes 3a and 3b similar to the example shown in FIG. 4 are formed on the printed wiring board 9. The legs 2a and 2b of the supply electrode 2 are inserted into the leg insertion holes 15a and 15a formed in the printed wiring board 9 so that the supply electrode 2 is parallel to and concentric with the fan-shaped electrodes 3a and 3b. 1
5b, soldered and fixed. This printed wiring board 9 has approximately two
Two holes 16a and 16b are formed near both ends of the equally dividing center line, into which screws 12a and 12b of the case 10, which will be described later, are inserted. In this printed circuit board 9, a plated dielectric liquid injection port 9a is formed between one hole 16a and one leg insertion hole 15a. 10
This is a case in which a dielectric liquid container is formed together with the printed circuit board 9. This case 10 includes a substantially circular base 10b and a partition wall 10c formed around the periphery of the base 10b. Screws 12 formed in
Projections 15a and 15b are formed into which portions a and 12b are inserted. The screws 12a and 12b are connected to the protrusion 15
a, 15b, holes 16a, 16b of printed circuit board 9
Then, it is screwed into the nut 13 via the O-ring 14. Then, the case 10 is the printed circuit board 9
is fixed to form a container. An injection port 9a formed on the printed circuit board 9 is inserted into the formed container.
Then, a dielectric liquid such as silicone oil is injected to approximately 1/2 of the effective area inside the container. When the injection of the dielectric liquid is completed, the injection port 9a is opened during the soldering work of the printed circuit board 9.
is sealed by soldering. The container described above is then sealed.

Note that the inclination of the tractor or the like detected by the inclination sensor shown in FIG. 1 may be displayed using a display device.

Note that the injection port 9a formed on the printed circuit board 9
The position is not limited to the illustrated example, but may be any position that is at least one-half level of the container consisting of the case 10 and the printed circuit board 9.

[Effect of idea]

According to this invention, the case 10 has a thin wall portion 10a.
is formed, and pressure fluctuations in the gas inside the tilt sensor are absorbed by expansion and contraction of the thin wall portion 10a, resulting in the effect of reducing measurement errors.

Further, according to this invention, since the dielectric liquid injection port 9a is formed in the printed circuit board 9, this injection port 9a is used when soldering the printed circuit board 9.
A can be reliably sealed with solder. Therefore,
Since there is no need for a rubber stopper to block the injection port, and there is no need to insert the rubber stopper into the injection port, there are advantages in that material costs can be reduced and work efficiency can be improved.

Furthermore, in the past, it was necessary to fix the rubber plug inserted into the injection port 9a with adhesive, but if dielectric liquid adhered to the vicinity of the injection port, sufficient adhesion could not be achieved, resulting in an incomplete seal. However, with this invention, even if the dielectric liquid adheres to the vicinity of the injection port, it dries quickly due to the heat generated during the soldering process of the printed wiring board, so the solder can be reliably applied. It also has the effect of being firmly fixed to the injection port 9a and achieving a completely sealed state.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of this invention, Fig. 2 is an explanatory diagram of the main part of the example shown in Fig. 1, Fig. 3 is a diagram showing an example of a circuit for obtaining a voltage according to the inclination angle, and Fig. 4. 1 is a diagram showing a conventional example. 2 is a common electrode, 3a and 3b are fan-shaped electrodes, 5 is a dielectric liquid, 9 is a printed wiring board, 9a is an injection port, 10 is a case, and 10a is a thin wall portion.

Claims (1)

[Scope of Claim for Utility Model Registration] An airtight container that includes a printed wiring board as a part and has a thin wall portion and is filled with a dielectric liquid, and a device provided in the airtight container for injecting the dielectric liquid. In a capacitive tilt sensor comprising an injection port and a capacitance detection electrode provided in the sealed container, the injection port is provided on the printed wiring board, and during the soldering work of the printed wiring board. A capacitive tilt sensor in which the injection port is sealed with solder.