JP2731239B2 - Oil sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an oil sensor that detects the presence or absence of lubricating oil from a difference in resistance between air and lubricating oil.

[Problems to be Solved by the Related Art and the Invention] Generally, in a general-purpose engine, a vehicle engine, or the like, if the operation is continued without noticing that the lubricating oil is in an insufficient state, damage such as seizure is caused. An oil sensor that constantly monitors the oil level is provided to stop the engine or turn on a warning light to prevent damage to the engine if the amount of lubricating oil is insufficient.

An oil sensor of this type is disclosed in, for example,
No. 93417, those using a reed switch as disclosed in JP-A-62-26379, or those using a hydraulic switch, etc., but in oil sensors using a reed switch, a reed switch is used. , A float, a magnet, etc., are required, the configuration is complicated, and it must be assembled in the crankcase in advance, which is inconvenient to handle.

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

On the other hand, in other technical fields, a sensor that measures the resistance of a fluid to detect a fluid fluctuation amount and the like is known.

This so-called fluid sensor is composed of a sensor inner electrode and a sensor outer electrode surrounding the sensor inner electrode at a predetermined interval, a so-called sensor body.From a change in the resistance value between the two electrodes immersed in the fluid, It detects volume fluctuation of the fluid or the concentration of the fluid.

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

When mass-producing this fluid sensor, it is necessary to mold the sensor body with a die such as die-casting, but it is necessary to consider the draft angle of the hollow portion into which the sensor internal electrode is loosely inserted at the time of molding. . However, if this draft is increased, the distance between the sensor inner electrode and the inner wall of the hollow portion of the sensor body, that is, the distance between the electrodes changes as the distance from the electrode tip portion to the base portion changes, and the electrode tip portion changes. In addition, different resistance values are detected at the electrode base.

Therefore, when the fluid sensor is used as an oil sensor, if the distance between the electrodes is large, the oil in the oil pan during the operation of the engine is affected by the undulation of the oil. In addition, if the distance between the electrodes is small, the viscosity of the oil, etc.,
The oil remains between the electrodes and cannot be detected even if the oil in the oil pan decreases. To address this,
In order to keep the resistance value within a certain range by making the distance between the electrodes of the oil sensor approximately equal from the electrode tip to the base end,
Although it is necessary to reduce the draft angle to some extent, the casting process takes time and production efficiency is reduced.

On the other hand, in die-cast molding, the surface roughness of the solid product after molding is large, and in particular, the hollow wall surface that defines the distance between the electrodes of the sensor body needs to be post-processed. There is a problem that causes a rise in product cost.

Further, since the conventional fluid sensor is mainly composed of a metal material, it is heavy and is inconvenient to handle at the time of shipping.

On the other hand, the oil sensor only needs to detect the presence or absence of lubricating oil, and does not need to detect fluctuations in the amount of lubricating oil, and does not 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 is not only easy to mold, does not require post-processing, is excellent in mass productivity, and
An object of the present invention is to provide an oil sensor that can make the distance between electrodes substantially constant, can appropriately detect the presence or absence of oil, is lightweight, has good handleability, and can reduce costs. I have.

[Means and Actions for Solving the Problems] An oil sensor according to the present invention includes a sensor body which also serves as a sensor outer electrode in which a sensor inner electrode is loosely inserted and which is provided at a predetermined interval around the sensor inner electrode. It is characterized by the fact that conductive resin is injection-molded into a material, which not only facilitates the molding of the sensor body, but also eliminates the need for post-processing and makes the distance between the electrodes substantially constant. The presence or absence of oil can be properly detected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The drawings show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an oil sensor, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. FIG.

(Configuration) The symbol A in the figure is an oil sensor.
The sensor body which also serves as the external electrode of the sensor is injection-molded using a conductive resin containing a conductive material such as carbon.

A screw head 1a is formed on the head of the sensor body 1, a flange 1b is formed below the screw head 1a, and a screw portion 1c is formed below the neck. Further, the sensor body 1
A hollow portion 1e penetrating from the head (base) side in the direction of the tip portion 1d is formed, and an air vent hole 1f opening in the hollow portion 1e is formed in the middle of the sensor body 1. .

Further, a step 1g is formed on the base side of the hollow portion 1e of the sensor body 1, and a sensor electrode guide 2 is formed on the step 1g.
Step 2a is hooked. This electrode guide 2 in the sensor
Is made of a high-resistance insulating resin material having heat resistance.

A groove 2b is provided under the neck of the step 2a of the sensor inner electrode guide 2, and the sensor body 1 is inserted into the groove 2b.
The O-ring 3 for sealing between the inner wall of the hollow portion 1e and the groove 2b is interposed. Further, the tip of the sensor inner electrode guide 2 forms a tapered surface 2c that converges in the tip direction,
Further, the diameter of the body between the tapered surface 2c and the groove 2b of the sensor inner electrode guide 2 is set to the hollow portion of the sensor body 1.
It is formed to be the same as or slightly smaller than the inner diameter of 1e.

Also. The entire circumference of the sensor inner electrode guide 2, or
At least a portion of the hollow portion 1e exposed on the tip portion 1d side, that is, the tapered surface 2c and the tip surface thereof, in order to prevent lubricating oil from adsorbing, heat resistance, insulation, non-lipophilicity of fluororesin or the like. Is coated.

The base of the sensor inner electrode 4 made of a metal pipe or the like is fitted into the center of the sensor inner electrode guide 2. The sensor inner electrode 4 is molded integrally with the sensor inner electrode guide 2 and has a rib 4a for retaining the ring at its base. Furthermore, this sensor inner electrode 4
A small hole 4c for solder immersion which communicates with the hollow portion 4b is formed in the tip end surface of the hole.

The inner sheath 5a of the heat-resistant shield wire 5 inserted from the top side of the sensor inner electrode guide 2 is inserted into the hollow part 4b of the sensor inner electrode 4, and the core wire 5b protruding from the tip of the inner sheath 5a. Is in contact with the bottom of the hollow portion 4b, and is connected and fixed to the bottom of the hollow portion 4b by solder permeating through a small hole 4c formed in the tip end surface of the sensor internal electrode 4 during the automatic soldering process. ing.

Further, a shield wire 5d exposed from the tip of the jacket 5c of the shield wire 5 is spread on the top surface of the sensor internal electrode guide 2, and a conductive washer 6 is brought into contact with the upper surface thereof. A conductive clip washer 7 whose outer periphery bites into the inner wall of the hollow portion 1e of the sensor body 1 to prevent it from coming off is brought into contact with the upper surface, and the shield wire 5d and the sensor body 1 bite into the clip washer 7. It is conducted through the section.

A plug 8 made of an insulating material such as an epoxy resin is fitted and fixed on the upper surface of the clip washer 7, and the hollow portion 1 e of the sensor body 1 is inserted through the plug 8.
And between the shield wire 5 and the jacket 5c of the shield wire 5.

On the other hand, a pin connector 9 connected to the control device 15 is connected to the other end of the shield wire 5, and the outer periphery of the pin connector 9 is covered with a waterproof cap 10.

Reference numeral 11 denotes an oil pan provided at the bottom of the crankcase of the engine, and a sensor mounting opening 11a for screwing and fixing the oil sensor A via a packing 12 is formed on one side of the oil pan 11.

(Operation) Next, the operation of the embodiment having the above configuration will be described.

First, a predeterminedly assembled oil sensor A is inserted through a sensor mounting opening 11a formed on one side of an oil pan 11 of an engine via a packing 12, and is screwed and fixed by a screw portion 1c of the sensor body 1 (FIG. 3). State).

 Further, the pin connector 9 is connected to the control device 15.

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

If the lubricating oil is sufficiently stored in the oil pan 11 during operation of the engine, the tip of the sensor body 1 and the sensor inner electrode 4 is immersed in the lubricating oil, and the electrode between the sensor body 1 and the sensor inner electrode 4 The resistance of the lubricating oil is detected based on the distance.

Since the resistance value of the lubricating oil is smaller than the space insulation resistance value between the electrodes, the lubricating oil shortage determining means of the control device 15
In 15a, the presence or absence of lubricating oil is determined based on the difference between the two resistance values.

Therefore, the oil sensor A is not required to detect the amount of the lubricating oil, but only to detect the presence or absence of the lubricating oil in the oil pan up to a predetermined level. The resistance value becomes extremely small compared to the resistance value of the lubricating oil due to the inclusion of a conductive material such as carbon, and the resistance value of the sensor body 1 is included in the range of the detection error.

On the other hand, by using a conductive resin as the material of the sensor body 1, not only weight reduction can be realized, but also injection molding becomes possible, handling becomes easy, and the manufacturing cost of the mold is reduced.

Furthermore, since the sensor body 1 is formed from resin, the draft angle can be reduced, and the distance between the electrodes between the sensor inner electrode 4 and the inner wall surface of the hollow portion 1e of the sensor body 1 can be reduced from the base to the tip of the shaft. It can be kept almost constant and appropriate, and the resistance value of the lubricating oil can be detected at a substantially constant value, so that the detection accuracy is improved.

Further, since the sensor body 1 is made of a resin product, the surface roughness is small. Therefore, for example, not only the post-processing of the sliding contact surface of the hollow portion 1e with the O-ring 3 is unnecessary, but also the surface roughness is reduced. The detection accuracy is further improved by being included in the error range of the distance between the electrodes.

In addition, since the sensor body 1 contains carbon,
Sufficient mechanical strength can be ensured, and vibration resistance and durability are improved.

On the other hand, when the lubricating oil stored in the oil pan 11 runs short and the tip of the oil sensor is exposed from the lubricating oil surface, the space insulation resistance value is determined by the distance between the sensor body 1 and the electrode 4 inside the sensor. Is detected, the lubricating oil shortage judging means 15a of the control device 15 displays an alarm on the lubricating oil shortage displaying means 15b, stops the engine and informs the operator of the lubricating oil shortage, and Prevent burn-in and the like.

Further, if the mounting level of the front end surface of the oil sensor A is variably set, only the warning display can be operated without stopping the engine before the shortage of the lubricating oil occurs.

The present invention is not limited to the above embodiment. For example, the electrode 4 in the sensor may be formed of a conductive resin.

[Effects of the Invention] As described above, according to the present invention, a sensor body that also serves as a sensor external electrode, into which a sensor internal electrode is loosely inserted, and which is provided at a predetermined interval around the sensor internal electrode, is provided.
Since the conductive resin is formed on the material, it is easy to mold and does not require post-processing, it is also excellent in mass productivity, and it can detect the presence or absence of oil properly, and it is lightweight and easy to handle, In addition, excellent effects such as reduction of production cost can be achieved.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an oil sensor, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. FIG. 1 ... Sensor body, 4 ... Sensor electrodes.

Claims (1)

(57) [Claims] A sensor body in which a sensor inner electrode is loosely inserted and which is also used as a sensor outer electrode opposed to the sensor inner electrode at a predetermined interval around the sensor inner electrode is formed by injection molding a conductive resin material. Oil sensor.