JPS6226575Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for electrically detecting the amount of oil in an oil pan of an internal combustion engine. In particular, the present invention relates to an oil pan oil amount detection device for an automobile internal combustion engine.

[Conventional technology]

Conventionally, in this type of detection device, as shown in FIG. 1, a pipe body 2 is installed vertically at the inner bottom of an oil pan 1, and reed switches 3 and 4 are installed inside the pipe body 2 at the upper or lower part, respectively. Furthermore, a float 6 containing a permanent magnet and floating on oil 5 is loosely inserted into the tube body 2. 7 is a float stopper, and 8 and 9 are lead wires which are electrically connected to the reed switches 3 and 4, respectively.

[Problem that the invention attempts to solve]

In a conventional device with such a configuration, the oil pan 1
When the amount of oil in the tank falls below a predetermined level, the reed switch 4 is closed and an oil shortage is detected. However, when the automobile travels on a rough road, the oil 5 shakes due to vibrations, causing the float 6 to vibrate up and down, resulting in a drawback that the tube body 2 is easily broken. Further, when the depth of the oil pan 1 differs depending on the vehicle type, a detection device unique to each vehicle type is required, resulting in a drawback of poor versatility. Furthermore, if iron powder or iron scraps are mixed into the oil 5, the iron powder or the like will adhere to the permanent magnet of the float 6, resulting in malfunction.

On the other hand, a technology has been proposed in which a pair of electrodes is attached to the tips of the electrodes, and a resistance-capacitance oscillation circuit is used that uses the capacitance formed between the electrodes as the amount of displacement to detect changes in the oil amount in the oil pan (in practice). Gansho 56-
35930, Utility Model Publication No. 60-29618).

However, since this electrode is made of brass and is inserted directly into the oil, there is a problem that iron powder or iron chips in the oil may adhere to the electrode surface and cause malfunction. Since minute changes in the oil level in the oil pan appear as changes in the capacitance value, changes in the oil amount cannot necessarily be detected accurately, and there is a problem in that the system lacks versatility for different oil pans.

This invention solves the above-mentioned drawbacks; it does not break due to vibration, is versatile for different oil pans, and can accurately detect changes in oil volume without malfunctioning. The purpose is to provide equipment.

[Means for solving problems]

The present invention includes a first electrode and a second electrode opposite to this electrode on the bottom or side of an oil pan of an internal combustion engine, and the first electrode and the second electrode are connected to each other. An oil pan oil amount detection device, which is formed in a structure in which oil inside the oil pan flows between electrodes, and includes a circuit for detecting capacitance between the first electrode and the second electrode. , each surface of the first electrode and the second electrode is covered with a non-conductive film, one of the first electrode and the second electrode is formed into a cylindrical shape, and the other one is formed into a cylindrical shape. It is characterized in that the electrode is arranged in the shape of a rod inside the cylinder.

[Effect]

The capacitance of the capacitor formed between the first electrode and the second electrode changes as the amount of oil filled between the two electrodes changes.

By detecting this change in capacitance, the amount of oil in the oil pan can be detected.

The surfaces of the first and second electrodes are coated with a non-conductive film, which prevents impurities from adhering to them, and since they are formed in a cylindrical shape, they can be used accurately without being affected by small fluctuations in the oil level. Changes in oil amount can be detected.

〔Example〕

The following will be discussed in detail based on the drawings of the embodiment.

FIG. 2 is a structural diagram of an apparatus according to an embodiment of the present invention, and FIG. 3 is an enlarged sectional view of the main parts thereof. 11 is a first electrode, and 12 is a second electrode. A cylindrical first electrode 11 is vertically disposed on the inner bottom of the oil pan 1, and a rod-shaped second electrode 12 is disposed at the center of the cylinder. The heights of these two electrodes 11 and 12 are determined according to the height of the oil level when a predetermined amount of oil is stored in the oil pan 1. first electrode 1
Holes 13 and 14 are formed in the upper and lower parts of the oil pan 1, respectively, into which the oil 5 inside the oil pan 1 flows. Further, the base of the first electrode 11 is screwed and fixed to a nut 16 welded to the inner bottom of the oil pan 1.

Lead wires 8 and 9 are electrically connected to the base ends of the first electrode 11 and the second electrode 12, respectively. Further, each surface of the first electrode 11 and the second electrode 12 is covered with a plastic film which is a non-conductive film. 17 and 18 are insulating spacers, which connect the first electrode 11 and the second electrode 12.
and electrically insulate these two electrodes 1
The distance between 1 and 12 is fixed at a predetermined interval. A capacitor is formed by the first electrode 11 and the second electrode 12. Depending on the change in the amount of oil in the oil pan 1, the amount of oil filled between these two electrodes 11 and 12 changes, and when the electrodes 11 and 12 come into contact with air due to lack of oil, the dielectric constant changes, so the capacitor's static The capacitance also changes.

Due to the plastic film coating, even if conductive impurities such as iron powder are mixed into the oil, the capacitance changes depending on the amount of oil filled.

FIG. 4 is an electrical circuit diagram of a device according to an embodiment of the present invention. 20 is the above capacitor, and inductor 2
1 in parallel to form a resonant circuit. This becomes a resonant circuit that determines the oscillation frequency of the oscillator 22, and the output signal of the oscillator 22 is given to a filter 23. The signal that has passed through the filter 23 is rectified by a detector 25 and applied to a relay winding 26. A relay switch 27 is opened and closed by a relay winding 26.

In such a device, when there is a predetermined amount of oil in the oil pan 1, the output of the oscillator 22 passes through the filter 23 and appears at the relay winding 26.
When the oil in oil pan 1 decreases, capacitor 2
A first electrode 11 and a second electrode 1 forming a
The area between 2 and 2 in contact with the air becomes larger, and the capacitance changes. As a result, the output frequency of the oscillator 22 changes and no longer passes through the filter 23, so that no signal appears in the relay winding 26. This closes the relay switch 27 and activates an alarm circuit (not shown) connected to this switch 27.

As is well known, the capacitance of capacitors with the same electrode structure is proportional to the dielectric constant of the dielectric interposed between the electrodes. The dielectric constant of air is approximately 1
The dielectric constant of lubricating oils commonly used in internal combustion engines is 2.2 to 4.7. Therefore, capacitor 2
A first electrode 11 and a second electrode 1 forming a
If everything between 2 is in contact with air, a change in capacitance of 2 to 4 times will occur. The structure of the example has a capacitance of about 200 pF, and the oscillator 22
If the output frequency is set to about 2MHz, the reduction will be approximately 50%.
It is possible to easily obtain a filter 23 or a detector 25 that can noticeably detect a decrease in the capacity of the waveform.

FIG. 5 is a circuit diagram of another embodiment. In this example, the output frequency of the oscillator 22 is constant, and the pass frequency of the filter 23 is changed by the capacitor 20. 28 is an inverter that inverts the presence or absence of a signal, and a light emitting diode 29
give to The light emitting diode 29 is an alarm display placed at the driver's seat.

Although an example is shown in which the first electrode and the second electrode are installed vertically on the inner bottom of the oil pan, they are not limited to vertical installation and may be installed obliquely. It may be installed vertically or diagonally.

[Effect of idea]

As described above, the present invention has a simple structure, high mechanical strength, and is effective in preventing malfunctions caused by changes in capacitance caused by iron powder in oil adhering to the electrodes. can get.

In addition, since the electrode is formed in a cylindrical shape, it is possible to detect large changes in oil level without being affected by minute fluctuations in the oil level caused by vehicle vibrations, and to make accurate measurements. Can also be used for oil pans.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of a conventional device. FIG. 2 is a structural diagram of a device according to an embodiment of the present invention. FIG. 3 is an enlarged sectional view of the main part. FIG. 4 is an electric circuit configuration diagram of an embodiment of the present invention. FIG. 5 is an electric circuit configuration diagram of another example device. 1... Oil pan, 5... Oil, 8, 9... Lead wire, 11... First electrode, 12... Second electrode, 13, 14... Hole, 16... Nut, 17,
18...Spacer, 20...Capacitor, 21...
...inductor, 22 ... oscillator, 23 ... filter, 25 ... detector, 26 ... relay winding, 27
...Relay switch, 28 ...Inverter, 29
...Light emitting diode.

Claims (1)

[Claims for Utility Model Registration] A first electrode and a second electrode opposite to this electrode are provided on the bottom or side of an oil pan of an internal combustion engine, and the first electrode and the second electrode are connected to each other. is formed in a structure in which oil inside the oil pan flows between these two electrodes, and includes a circuit for detecting capacitance between the first electrode and the second electrode. In the amount detection device, each surface of the first electrode and the second electrode is coated with a non-conductive film, and one of the first electrode and the second electrode is formed into a cylindrical shape. An oil pan oil amount detection device characterized in that the other electrode is arranged in the shape of a rod inside the cylinder.