JPH0522858Y2 - - Google Patents

Description

[Detailed explanation of the invention] Purpose of the invention [Industrial field of application] The invention is aimed at reducing the amount of alcohol used in automobile engines by mixing alcohol such as methanol or ethanol with other fuels such as gasoline. The present invention relates to an alcohol concentration detection device for detecting the alcohol concentration of alcohol.

[Prior Art] Conventionally, as one type of alcohol concentration detection device, as described in Japanese Patent Application Laid-Open No. 57-101753, two electrode plates facing each other are placed inside an insulating housing. It is known that the alcohol mixed fuel is fixedly stored in the container, the alcohol mixed fuel flows into the storage part, and the impedance between the electrode plates is measured to detect the alcohol concentration in the alcohol mixed fuel.

This type of alcohol concentration detection device was developed by focusing on the fact that the impedance between both electrode plates changes depending on the alcohol concentration in the alcohol mixed fuel filled between the two electrode plates. The alcohol concentration is detected by indirectly detecting the impedance between the two.

[Problems to be solved by the invention] However, in the conventional device, a circuit is configured in a separate location from the main body housing of the detection device, and a circuit board for attaching an electrode plate to the housing, There was a problem in that the circuit boards that constituted the circuits had to be provided separately, and that the number of parts and the wiring for connecting them were required. Another problem was that the signal from between the electrode plates deteriorated while being transmitted from the sensor body to a circuit located far away, making it difficult to accurately detect the alcohol concentration. .

Moreover, since the terminal electrode passes through multiple electrode plates and electrically conducts or insulates them, the configuration is complicated, and poor conductivity and shorts are likely to occur. There was a problem that it may interfere with concentration detection.

Therefore, the present invention aims to solve the above problems, and is an alcohol concentration detection device that has a small number of parts, prevents signal deterioration, has a simple configuration, is less likely to cause malfunctions or shoots, and is less likely to have air bubbles attached. Our goal is to provide the following.

Structure of the invention [Means for solving the problems] In order to achieve the above object, the present invention has the following structure as a means for solving the problems. That is, two electrode plates arranged facing each other are hung on an insulating plate, alcohol mixed fuel is filled between the electrode plates, and a change in impedance between the electrode plates is converted into an electrical signal by a conversion circuit. In an alcohol concentration detecting device for detecting alcohol concentration using a method, the two electrode plates are each formed in a spiral shape and are arranged to face each other, and the two electrode plates are fixed by an insulator member, and the two electrode plates are respectively an overhang is provided, one end of a terminal electrode is fixed to the overhang, the other end of the terminal electrode is fixed and hung on the insulating plate, and the insulating plate is on the opposite side to the side on which the electrode plate is hung. This is the configuration of an alcohol concentration detection device characterized in that at least the conversion circuit is formed as a thick film integrated circuit.

[Function] The alcohol concentration detection device having the above configuration has the following functions:
A conversion circuit as a thick film integrated circuit is integrally formed on the insulating plate on the opposite side to the side on which the electrode plate is hung, thereby reducing the impedance between the electrode plates while shortening the transfer distance between the electrode plate and the conversion circuit. The alcohol concentration is detected by converting changes in alcohol into electrical signals.

One end of the terminal electrode is fixed to the protruding portion, and the other end of the terminal electrode is fixed to and suspended from an insulating plate. Furthermore, air bubbles flow along the spiral electrode plate, preventing the air bubbles from adhering to the electrode.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a sectional view of an alcohol concentration detection device which is an embodiment of the present invention. This alcohol concentration detection device includes a hollow metal or synthetic resin housing 1 provided in a fuel supply path to an alcohol engine (not shown) operated with alcohol mixed fuel. A fuel inlet 2 and a fuel outlet 4 are respectively provided. The fuel inlet 2 is connected to a fuel tank (not shown), and the fuel outlet 4 is connected to means for supplying fuel to an intake system of the engine.

Further, an insulating plate 8 is fitted into the opening 6 formed in the housing 1, and one end of the insulating plate 8 passes through the insulating plate 8 and is connected to the opposite surface 8a of the insulating plate 8. Two protruding terminal electrodes 1
0 and 12 are fixed. Incidentally, a fuel chamber 26 is formed surrounded by the housing 1 and the insulating plate 8, and the fuel chamber 26, the fuel inlet 2, and the fuel outlet 4 are connected to each other.
are in communication.

The electrode plates 14 and 16 are housed in the fuel chamber 26, and the two spirally formed electrode plates 1
The electrode plates 14, 16 are fixed at their center portions with an insulator member 18 so as to form a predetermined interval.
Protruding portions 14a and 16a are provided respectively from the
The ends of terminal electrodes 14 and 16 are fixed to these projecting portions 14a and 16a, respectively.

Next, the electric circuit of the alcohol concentration detection device of this embodiment will be explained.

As shown in FIG. 2, this electric circuit consists of an oscillation circuit 40 that outputs a signal at a predetermined constant frequency, for example, a frequency of 50 KHz, a conversion circuit 42, and the impedance between the electrode plates 14 and 16 by Zh. The equivalent circuit 44 shown in FIG. This conversion circuit 42 connects the oscillation circuit 40 and the equivalent circuit 44, that is, one terminal electrode 10, and the oscillation circuit 40 is connected to a semiconductor integrated circuit IC1 that converts an impedance signal into a voltage signal. In addition, the equivalent circuit 44, that is, the other terminal electrode 1
2 is connected to the semiconductor integrated circuit IC1, and is also connected to one end of the diode D1. The other end of this diode D1 is connected to one end of a capacitor C1 whose other end is grounded, one end of a resistor R1 whose other end is also grounded, and one end of a resistor R2. The other end of the resistor R2 is connected to a semiconductor integrated circuit IC2 that amplifies the DC voltage, one end of a resistor R3, and one end of a resistor R4. The other end of this resistor R4 is connected to the output side of the semiconductor integrated circuit IC2.

On the other hand, the above-mentioned conversion circuit 42 is disposed on the opposite surface 8a of the insulating plate 8.
A conductor pattern 50 corresponding to the conversion circuit 42 is screen printed on a, and a resistor pattern 52 of resistors R1, R2, R3, and R4 is printed on the conductor pattern 50.
After being screen printed and fired, the semiconductor integrated circuits IC1, IC2, diode D1 and capacitor are printed.
A chip component 54 such as C1 is soldered to the conductive pattern 50 to constitute the conversion circuit 42. Further, one ends of the terminal electrodes 10 and 12 are also soldered to the conductor pattern 50, thereby firmly fixing the terminal electrodes 10 and 12 and electrically connecting them to the conversion circuit 42. Note that the accuracy of the resistor pattern 52 can be further improved by laser trimming.

Further, a lid 56 made of metal or synthetic resin is fixed to the opening 6 of the housing 1.
This lid 56, the opening 6 of the housing 1, the insulating plate 8
A space surrounded by the opposite surface 8a is filled with a thermosetting resin sealant 58. Thereby, the conversion circuit 42 is integrally formed with the terminal electrodes 10 and 12 on the opposite surface 8a of the insulating plate 8 by a so-called well-known thick film process, thereby forming a thick film integrated circuit. This prior art thick film process allows conventional processes, equipment, and materials to be applied as they are, and can be manufactured at low cost. Further, by making the housing 1 and the lid 56 metallic, the conversion circuit 42 has a shielded configuration, which blocks electrical noise from the outside, and prevents the conversion circuit 42 from picking up noise. Furthermore, the oscillation circuit 40 and the conversion circuit 42 may be integrally formed as a thick film integrated circuit.

Next, the operation of the alcohol concentration detection device of this embodiment will be explained.

First, alcohol mixed fuel is supplied into the housing 1 through the fuel inlet 2, and
The inside is filled with alcohol mixed fuel, and one electrode plate 1
4 and the other electrode plate 16 is filled with alcohol mixed fuel, and the alcohol mixed fuel flows out from the fuel outlet 4. When the alcohol mixed fuel is filled between the electrode plates 14 and 16, a signal with a constant frequency is output from the oscillation circuit 40, and this signal is transmitted to the semiconductor integrated circuit via the terminal electrode 10, the electrode plates 14 and 16, and the terminal electrode 12. Input to circuit IC1.

On the other hand, the space between the electrode plates 14 and 16 filled with alcohol mixed fuel is represented as an equivalent circuit 44 in which a resistor and a capacitor are connected in parallel, and changes as the alcohol concentration of the filled alcohol mixed fuel changes. It has a certain finite impedance value.

Therefore, the signal output from the oscillation circuit 40 is
It changes according to this impedance value, and the impedance signal is converted into a voltage signal by the semiconductor integrated circuit IC1. This voltage signal is connected to the diode
It is rectified by D1, capacitor C1, and resistor R2 and converted into a DC voltage signal, and further, the semiconductor integrated circuit
It is amplified by IC2 and output as a voltage output signal. This output signal is a signal that corresponds to the alcohol concentration, and the alcohol concentration can be determined by comparing it with an output signal determined using an alcohol mixed fuel whose alcohol concentration is known in advance.
The fuel flow rate to the engine, ignition timing, etc. are controlled based on the determined alcohol concentration. still,
In addition to a circuit that converts an impedance signal into a DC voltage output signal, the conversion circuit 42 may be, for example, a circuit that can obtain a pulse number proportional to impedance or a circuit that can obtain a pulse width proportional to impedance.

As described above, in the alcohol concentration detection device of this embodiment, when the alcohol mixture fuel is filled between the electrode plates 14 and 16, a signal of a constant frequency output from the oscillation circuit 40 is transmitted to the electrode plates 14 and 16 and the terminal electrode. The impedance signal is directly input to a conversion circuit 42 formed integrally with the insulating plate 8 through the impedance signals 10 and 12, and the impedance signal is rectified and amplified by the conversion circuit 42 and output as a voltage output signal.

Therefore, according to the alcohol concentration detection device of this embodiment, since the conversion circuit 42 is integrally formed on the insulating plate 8 as a thick film integrated circuit, the insulating plate 8 on which the electrode plates 14 and 16 are suspended, and the conversion circuit 42 The number of circuit board components can be reduced from two to one, and there is no need for wiring for these connections. In addition, electrode plate 1
Since the minute signals from 4 and 16 are directly input to the conversion circuit 42, signal deterioration is small and, therefore, more accurate alcohol concentration can be detected.

Moreover, since the terminal electrodes 14, 16 are fixed to the protruding parts 14a, 16a, the terminal electrodes 10, 12 can be attached to the electrode plates 14, 16a.
16, there is no need to insulate the terminal electrodes 10, 12 and the electrode plates 14, 16, the structure is simple, and conduction failures, shorts, etc. are less likely to occur. In addition, the electrode plates 14, 16
Since it is sloped, it is difficult for air bubbles to adhere to it, and even if air bubbles adhere to it, it is easy to remove it. If the central axis of the spiral is tilted, it becomes even more difficult for air bubbles to adhere.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention.

Effects of the Invention As detailed above, the alcohol concentration detection device of the present invention directly inputs the input to the conversion circuit, so the conversion circuit is integrally formed as a thick film integrated circuit on an insulating plate on which the electrode plate is suspended. By sharing the insulating board for hanging the board and the conversion circuit board, the number of circuit board parts can be reduced from two to one, and the deterioration of minute signals from the electrode board can be reduced, making it more accurate. Alcohol concentration can be detected. In addition, since the terminal electrode is fixed to the protruding portion, the structure is simplified and poor conduction, shorting, etc. are less likely to occur. Furthermore, since the electrode plate is inclined, air bubbles are less likely to adhere, and even if air bubbles adhere, they can be easily removed and accurate alcohol concentration can be measured.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an alcohol concentration detection device as an embodiment of the present invention, Fig. 2 is an electric circuit diagram of the alcohol concentration detection device, and Fig. 3 is an enlarged perspective view of an electrode plate of the present embodiment. . 1... Housing, 8... Insulating plate, 10, 12
... Terminal electrode, 14, 16 ... Electrode plate, 1
4a, 16a... overhanging portion, 42... conversion circuit, 58... sealing material.

Claims (1)

[Claims for Utility Model Registration] A converting circuit in which two electrode plates arranged opposite to each other are hung on an insulating plate, and alcohol mixed fuel is filled between the electrode plates to convert changes in impedance between the electrode plates. In an alcohol concentration detection device that detects alcohol concentration by converting it into an electric signal, the two electrode plates are each formed in a spiral shape and are arranged to face each other, and the two electrode plates are fixed by an insulator member, and A projecting portion is provided from each of the electrode plates, one end of the terminal electrode is fixed to the projecting portion, the other end of the terminal electrode is fixed and hung to the insulating plate, and the side to which the electrode plate is hung is An alcohol concentration detection device characterized in that at least the conversion circuit is formed as a thick film integrated circuit on the insulating plate on the opposite side.