JPH02310427A - Oil sensor - Google Patents

Abstract

PURPOSE:To reduce a cost and to improve reliability by forming an inner electrode for sensor which is movably inserted at the shaft center of a cylindrical outer electrode for sensor, with a conductive resin as the base material. CONSTITUTION:A sensor body 1 which is used also as the outer electrode for sensor is injection-molded with the conductive resin containing a conductive material like a carbon, etc., as the base material. A stepped part 1g is formed at the base part of hollow part 1e on the body 1, and a stepped part 2a of an inner electrode guide 2 for sensor is hooked on that stepped part 1g. This guide 2 is formed with a high resistance insulation resin having a heat resistance as the base material. Further, the inner electrode 4 for sensor is fitted in the shaft center of guide 2, and the electrode 4 is injection-molded with the conductive resin containing several percent conductive material like the carbon, etc., as the base material. With such an arrangement, the cost is reduced and reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oil sensor that detects the presence or absence of 1IVl lubricating oil from the difference in resistance between air and lubricating oil.

[Problems that conventional techniques and inventions attempt to solve] Generally,
General-purpose engines, vehicle engines, etc., are equipped with oil sensors that constantly monitor the lubricant level to prevent damage such as seizure if they continue to operate without paying attention to the lubricant shortage. If there is a shortage, the engine is stopped or the three warning lights are turned on to prevent engine damage.

As this type of oil sensor, for example, JP-A-62-
93417 and Japanese Patent Application Laid-Open No. 62-26379, there are oil sensors that use a switch or oil pressure switch, but oil sensors that use a reed switch do not use a reed switch. It requires component parts such as a switch, a float, and a magnet, which complicates the structure and requires that it be assembled in the crankcase in advance, making it inconvenient to handle.

Furthermore, an oil sensor using a hydraulic pressure switch cannot be used in a splash lubrication type engine that is not equipped with an oil pump, and has a problem with its versatility.

On the other hand, in other technical fields, sensors are known that measure fluid resistance and detect fluid fluctuations.

This so-called fluid sensor consists of an inner sensor electrode and an outer sensor electrode that surrounds the inner sensor electrode at a predetermined interval, and changes in the volume of the fluid due to changes in resistance between the two electrodes immersed in the fluid. Alternatively, it is used to detect fluid concentration or the like.

As described above, since the conventional fluid sensor detects the resistance value fluctuation of the fluid, it is necessary to use a metal material with relatively good conductivity for both the electrodes.

When mass-producing this fluid sensor, the electrodes in the sensor must be plastic-processed or VI-molded from a metal material, but in either case, post-processing is required, which poses a problem in increasing productivity. .

Furthermore, when the fluid sensor is used as an oil sensor for an engine, the tip of the electrode in the sensor made of a metal material tends to swing due to the influence of engine photography, and the guide member supporting the base of the electrode in the sensor It imposes a large burden and poses problems in terms of vibration resistance.

On the other hand, the engine oil sensor only needs to detect the presence or absence of lubricating oil, and there is no need to detect fluctuations in lubricating oil supply, so there is no need to use the conventional fluid sensor described above.

[Object of the Invention] The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an oil sensor that is not only easy to mold but also requires no post-processing, has excellent mass productivity, is lightweight, and has good vibration resistance. It is an object.

[Means and effects for solving the problems] The oil sensor according to the present invention has an inner electrode formed of a conductive resin and inserted loosely into the axial center of a cylindrical outer electrode of the sensor. Not only is it easier to mold the electrode, but post-processing is no longer necessary.

[Embodiments of the invention] Hereinafter, the present invention will be explained in detail based on the drawings.

The drawings show an embodiment of the present invention, and FIG. 1 shows an example of an oil sensor. 2 is a cross-sectional view taken along ■--■ in FIG. 1, FIG. 3 is a cross-sectional view taken along ■--■ in FIG. It is.

(Structure) Reference numeral A in the figure is an oil sensor, and a sensor body that also serves as the outer 1 m of the oil sensor A is injection molded into wood from a conductive resin containing a conductive material such as carphone.

A screw head 1a is formed at the head of this sensor body 1, seven flange 1b is formed at the lower part of the screw head 1a, and a threaded part 1C is formed at the lower part of the neck.

Further, a hollow portion 1e is formed in the sensor body 1 and extends from the head (base) side toward the tip portion 1d, and the hollow portion 1e1. : An open air bleed hole 1f is provided.

Further, in the sensor body 1, a step portion 1q is formed on the base side of the hollow portion 1e, and a step portion 2a of the in-sensor electrode guide 2 is hooked to this step portion 1q.

This in-sensor electrode guide 2 is made of a heat-resistant, high-resistance insulating resin material.

Further, a tg2b is provided as a ring at the lower part of the neck of the stepped portion 2a of the sensor internal electrode guide 2, and an O-ring is provided in this groove 2b for sealing between the inner wall of the hollow portion 1C of the sensor body 1 and the groove 2b. 3a is interposed. Further, the distal end of the intra-sensor ff1A guide 2 forms a tapered surface 2C that converges in the distal direction, and the diameter of the body between the tapered surface 2C of the intra-sensor electrode guide 2 and the tf42 b is as described above. The inner diameter of the hollow portion 1e of the sensor body 1 is the same as or slightly smaller than the inner diameter of the hollow portion 1e of the sensor body 1.

Also, in order to prevent lubricating oil from adsorbing on the entire circumference of the sensor electrode guide 2, or at least on the portion exposed to the tip 1d side of the hollow portion 1e, that is, on the tapered surface 2C and its tip surface. It is coated with heat-resistant, insulating, and non-oleophilic materials such as fluororesin.

Further, an internal sensor electrode 4 is fitted into the axial center of the internal electrode guide 2, and its tip faces toward the tip 1d of the sensor body 1.

Like the sensor body 1 described above, the sensor internal electrode 4 is injection molded from a conductive resin containing several percent of a conductive material such as carbon.

Further, a flange 4a is formed on the base side of the sensor internal electrode 4, and this flange 4a is fitted into four parts 2dk of a predetermined depth drilled in the base end surface of the sensor internal electrode guide 2, and a ring is inserted into the bottom surface of this recess 2d. 0 inserted into the provided stepped portion 2e.
The bottom surface of the flange 4a is sealed via the ring 3b.

Furthermore, a core wire 5b protruding from the tip of the inner sheath 5a of the heat-resistant shield wire 5 is coated on a protrusion 4b integrally formed at the base end of the sensor electrode 4, and is fastened to the protrusion 4b with a caulking ring 6. There is.

Further, an insulating washer 7 made of rubber or the like is brought into contact with the top surface of the electrode guide 2 in the sensor.
7, a shield wire 5d protruding from the outer sheath 5C of the shield wire V5 is spread out, and a conductive washer 8 is brought into contact with the upper surface of the shield wire 5d. A conductive clip washer 9 that bites into the inner wall of the hollow portion 1e and stops handling is brought into contact with the
The shield wire 5d and the sensor body 1 are electrically connected to each other through the biting portion of the clip washer 9.

Further, a plug 10 made of an insulating material such as EVO:1 resin is fitted and fixed on the upper surface of the clip washer 9, and is connected to the hollow portion 1C of the sensor body 1 through the plug 10. and the outer sheath 5 of the shield wire 5
There is a seal between C and C.

On the other hand, a pin connector 11 connected to a control device 15 is connected to the other end of the shield wire 5, and the outer periphery of this pin connector 11 is covered with a waterproof cap 12.

Reference numeral 13 denotes an oil pan provided at the bottom of the engine crankcase, and on one side of the oil pan 13 is formed a sensor attachment port 13a into which the oil sensor A is screwed and fixed via a gasket 14.

(for production) Next, the operation of the embodiment with the above configuration will be explained.

Insert the pre-assembled oil sensor △ into the sensor mounting port 13a formed on one side of the oil pan 13 of the engine via the gasket 14, and then insert the oil sensor △ into the threaded portion 1C of the sensor body 1.
The pin connector 11 is screwed and fixed, and the pin connector 11 is connected to the control device 15.

Next, when the key switch (not shown) is turned ON and the engine is driven, a voltage is applied to the lubricating oil shortage determining means 15a of the control device 15, and the oil sensor starts detecting lubricating oil shortage.

When lubricating oil is sufficiently stored in the oil pan 13, the tip 1d of the sensor body 1 and the sensor inner mold 4
The tip of the sensor 44 is immersed in the lubricating oil, and the resistance of the lubricating oil is detected between the sensor body 1 and the sensor electrode 4.

Since the resistance value of this lubricating oil is smaller than the space insulation resistance value between the sensor body 1 and the sensor internal electrode 4, the lubricating oil shortage determination means 15a of the control device 15 uses the difference between the two resistance values to lubricate the lubricating oil. Determine the presence or absence of oil.

That is, the sensor body 1 and sensor electrode 4 are resin products and are resistors themselves, but by containing a conductive material such as carbon, the volume resistivity is extremely small compared to the resistance value of the lubricating oil. Can be a value. Also,
The oil sensor A does not detect the lT1ff oil level, but only detects whether lubricating oil is at a specified level in the oil pan 13.
and the resistance value of the electrode 4 in the sensor are included in the detection error range.

In addition, by using conductive resin as the material for the sensor body 1 and sensor electrode 4, it is not only possible to achieve weight reduction, but also injection molding is possible, making handling easier.
In addition, the manufacturing cost of the mold is reduced, and post-processing is not required, resulting in improved production efficiency.

Furthermore, since the sensor body 1 contains carbon, sufficient mechanical strength can be ensured, and the photographic resistance and durability are improved.

On the other hand, when the engine is running, the sensor internal electrode 4 is easily photographed due to engine vibrations, which places a burden on the sensor internal electrode guide 2 that holds the base of the sensor internal electrode 4. Since it is made of resin, it is lightweight, which significantly reduces the above-mentioned burden.

In addition, when the lubricating oil stored in the oil pan 13 becomes insufficient and the tip of the oil sensor A is exposed from the lubricating oil surface, the space insulation resistance increases due to the distance between the sensor body 1 and the sensor internal electrode 4. The value is detected and the control device 1
The lubricating oil shortage determination means 15a of No. 5 displays a warning on the lubricating oil shortage display means 15b or stops the engine to inform the operator of the lubricant shortage, and also prevents the engine from seizing up. .

Further, by variably setting the mounting level of the tip surface of the oil sensor A, it is possible to operate only a warning display without stopping the engine before rll lubricant shortage occurs.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, the sensor outer electrode may be attached to the inner wall of the hollow portion 1e of the sensor body 1 without also serving as the sensor body 1. [Effects of the Invention] 2. As explained above, according to the present invention, the inner sensor electrode loosely inserted into the axial center of the cylindrical outer sensor electrode is formed of a conductive resin material, and molding is easy. Not only is it easy and eliminates the need for post-processing, but it also has excellent productivity, is lightweight, has improved vibration resistance, and not only can high reliability of the product be obtained, but it can also reduce production costs. Excellent effects are produced.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view of an oil sensor, FIG. 2 is a sectional view taken along ■--■ in FIG. 1, and FIG. 3 is a sectional view taken along FIG. 4 is a partial sectional view showing the oil sensor installed in the oil pan. 1... Electrode outside the sensor, 4... Electrode inside the sensor.

Claims (1)

[Claims] An oil sensor characterized in that an inner sensor electrode is loosely inserted into the axis of a cylindrical outer sensor electrode and is made of conductive resin.