JP3173139B2 - Liquid level detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detector suitable for detecting, for example, a liquid level of oil in an oil pan of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a liquid level detector for detecting a liquid level of oil in an oil pan of an internal combustion engine, a reed switch is provided in a cylinder, and a float having a magnet on the outer periphery of the cylinder is vertically movable. An arranged liquid level detector is usually used. However, this type of liquid level detector has a problem that it cannot be installed in a narrow space due to its large size due to having a float.

[0003]

Accordingly, it has been studied to detect the oil level using a thermistor type liquid level detector used for detecting the remaining amount of fuel or the like. With a simple structure in which the thermistor is installed in an open vertical cylinder, bubbles are generated in the oil in the oil pan during operation of the engine. The oil droplets adhere to the thermistor due to the adhesion or the waving of the oil surface, which causes a problem that the detection signal obtained from the thermistor fluctuates greatly and the detection operation becomes unstable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides a thermistor type liquid level detector capable of performing stable and accurate liquid level detection without being affected by bubbles or flying droplets. The purpose is to provide.

[0005]

In order to achieve the above object, a liquid level detector according to the present invention is a liquid level detector using a thermistor, wherein a cylindrical case having one end closed is arranged horizontally horizontally. A thermistor is arranged in the cylindrical case,
A hood portion is integrally extended at the other end of the cylindrical case, a wall portion with a liquid hole is provided in the hood portion to prevent intrusion of waves on the liquid surface, and a flow hole is provided on an outer peripheral portion of the cylindrical case. It is characterized by having been done.

[0006]

[Operation and Effect] The liquid level detector constructed as described above is used, for example, in the oil pan of the internal combustion engine so as to detect the oil level in the oil pan horizontally and horizontally.
At the time of detection, a voltage is applied to the thermistor, and a change in the resistance value caused by a temperature change of the thermistor is detected by a current, and the temperature of the thermistor differs depending on whether the thermistor is in the oil or outside the oil. Is detected.

[0007] During operation of the engine, a large number of bubbles are generated in the oil in the oil pan due to the entrainment of the return oil in the air, and a large number of scattered oil droplets are generated above the oil surface. Are arranged horizontally and horizontally, so that bubbles and oil droplets are unlikely to enter the cylindrical case, and it is possible to prevent the bubbles and oil droplets from adhering to the thermistor and unstable liquid level detection. Also,
Since the hood portion is provided to cover the liquid hole of the cylindrical case, entry of oil droplets and bubbles from the liquid hole is prevented, and the oil surface is formed on the oil surface by the wall provided at the end of the cylindrical case. Waves are prevented from entering, and the thermistor can stably detect the oil level by the oil entering from the liquid hole in the wall.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment of a liquid level detector for detecting an oil level in an oil pan of an internal combustion engine. 1
Is a cylindrical case having one end (left end) closed, and a large-diameter hood portion 2 is integrally extended at the other end (right end). Such a cylindrical case and the hood portion 2 are integrally formed of synthetic resin. Molded.

The closed left end of the cylindrical case is fixed to a mounting bracket (not shown), in which a terminal 3 connected to a lead wire is embedded, and a thermistor disposed in the cylindrical case 1. 5 are fixed to the terminal 3 by welding or soldering.

Further, a wall portion 6 is provided in the hood portion 2 so as to partition the inside, and the wall portion 6 is provided with four liquid holes 7 as shown in FIG. The wall 6 is provided to prevent the penetration of waves generated on the oil surface. To prevent the penetration of waves and improve the inflow of oil, the inner diameter of the liquid hole 7 is
For example, it is formed to 3 mm to 5 mm.

A terminal 8 is fixed inside the wall 6, and the other lead of the thermistor 5 is connected to the terminal 8. Further, a lead wire (not shown) is connected to the terminal 8. A plurality of flow holes 9 are formed in the outer peripheral portion at the left end of the cylindrical case 1. The flow holes 9 are mainly holes for air release or oil flow, and have a small diameter of, for example, 1 mm to 2 mm in order to prevent intrusion of bubbles.

The liquid level detector thus configured is installed horizontally at a predetermined level position in the oil pan in order to detect the oil level in the oil pan of the internal combustion engine.

At the time of detection, a voltage is applied to the thermistor 5 from a detection circuit (not shown), and a change in resistance value due to a temperature change of the thermistor 5 is detected by a current, and the thermistor 5 is in the oil or outside the oil. The oil level is detected based on the temperature of the thermistor 5 which differs depending on the above. The oil mainly enters and exits the cylindrical case 1 through the liquid hole 7 in the wall 6.

During operation of the engine, a large number of bubbles are generated in the oil in the oil pan due to the entrainment of return oil in the air, and a large number of scattered oil droplets are generated above the oil surface. 1 is installed horizontally and horizontally, bubbles and oil droplets are unlikely to enter the cylindrical case 1, and it is prevented that bubbles and oil droplets adhere to the thermistor 5 and the liquid level detection becomes unstable.

Further, since the hood portion 2 is provided so as to cover the liquid hole 7 of the wall portion 6, penetration of oil droplets and bubbles from the liquid hole 7 is prevented, and the hood portion 2 at the end of the cylindrical case 1 is prevented. The wall 6 provided inside prevents the wave generated on the oil surface from entering. Therefore, only oil flows in and out of the liquid hole 7 of the wall portion 6 and the oil surface in the cylindrical case 1 is stabilized.
The oil level can be stably detected via the thermistor 5.

FIGS. 4 and 5 show another embodiment. The shapes of the cylindrical case 1, the hood portion 2 and the like in this example are the same as those in the above-described embodiment, but the net 10 is disposed inside the hood portion 2. The mesh 10 has a mesh of about 0.5 mm, for example.
It is formed in a cup shape by a wire mesh of about 1 mm, and is assembled so as to be inserted into the inside of the hood portion 2 from the outside.

By providing the mesh body 10 inside the hood portion 2 as described above, even the bubbles floating on the oil surface can be effectively prevented from entering the case through the liquid hole 7.

FIGS. 6 and 7 show an embodiment of the liquid level detector of the second invention. One end (left end) of the cylindrical case 11 of the liquid level detector is formed in a closed cylindrical shape so that liquid can pass therethrough, and the other end (right end) of the opening is fitted with a synthetic resin lid 12. Will be closed.

When closing the right end of the cylindrical case with the lid 12, a cylindrical net 18 is inserted into the case along the inner periphery. On the other hand, the thermistor 5 is disposed in the cylindrical case 11, and one end of a lead wire thereof is connected to the metal cylindrical case 1.
1 is welded or soldered to the left end protrusion and connected to a lead wire (not shown). The other end of the lead wire of the thermistor 5 is connected to a terminal 13 attached to the outside of the lid 12.
, And a lead wire 14 is connected to the terminal 13.

At the left end of the cylindrical case 11, a small-diameter flow hole 1 is provided.
7 are formed, and a large-diameter liquid hole 15 is provided at the bottom of the case. In addition, small-diameter flow holes 16 are provided vertically at upper and lower positions on the outer peripheral portion of the lid 12.
The net 18 is located inside the flow holes 16 and 17 and the liquid hole 15.

The liquid level detector constructed as described above is installed horizontally at a predetermined level position in the oil pan via a bracket 19 in order to detect the oil level in the oil pan of the internal combustion engine. .

At the time of detection, a voltage is applied to the thermistor 5 from a detection circuit (not shown), and a change in resistance value due to a temperature change of the thermistor 5 is detected by a current, and the thermistor 5 is in the oil or outside the oil. The oil level is detected based on the temperature of the thermistor 5 which differs depending on the above. Oil flows into and out of the cylindrical case 11 mainly through the liquid hole 15 at the bottom.

During the operation of the engine, a large number of bubbles are generated in the oil in the oil pan due to the entrainment of the return oil in the air, and a large number of scattered oil droplets are generated above the oil surface. 11 is installed horizontally and horizontally, it is difficult for bubbles and oil droplets to enter the cylindrical case 11 and the thermistor 5
The liquid level detection does not become unstable due to bubbles or oil droplets adhering to the surface.

Since the mesh 18 is provided so as to cover the liquid hole 15 and the flow holes 16 and 17 from the inside, the intrusion of bubbles from the liquid hole 7 is prevented, and the liquid hole 15 and the flow holes 16 and 17 are prevented.
Only the oil flows in and out, and the oil surface in the cylindrical case 11 is stabilized, so that the thermistor 5 can stably detect the oil surface. In addition, the net 18 can prevent dust and foreign matter from entering the cylindrical case.

FIGS. 8 and 7 show another embodiment. In this embodiment, instead of the net 18 of the above-described embodiment, a short cylindrical net 20 is provided with a liquid hole in the outer peripheral portion of the cylindrical case 11. At 15 positions, it is mounted by the mounting ring 21. Other structures are the same as those in the above embodiment. Even in the case where the mesh body 20 is attached to the outer peripheral portion of the cylindrical case 11 as described above, the liquid level can be detected stably without exerting the influence of bubbles and scattered oil droplets as in the above embodiment. .

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a liquid level detector of the present invention.

FIG. 2 is a right side view thereof.

FIG. 3 is a sectional view thereof.

FIG. 4 is a cross-sectional view of another embodiment.

FIG. 5 is a front view thereof.

FIG. 6 is a sectional view showing an embodiment of the second invention.

FIG. 7 is a bottom view thereof.

FIG. 8 is a sectional view of another embodiment.

FIG. 9 is a bottom view thereof.

[Explanation of symbols]

1-cylindrical case, 2-hood part, 5-thermistor, 6-
Walls, 7-liquid holes, 9 flow holes.

Claims (3)

(57) [Claims] In a liquid level detector using a thermistor, a cylindrical case having one end closed is disposed horizontally and horizontally, a thermistor is disposed in the cylindrical case, and a hood is provided at the other end of the cylindrical case. The hood portion is provided with a wall portion having a liquid hole for preventing the intrusion of waves on the liquid surface, and a flow hole is provided on an outer peripheral portion of the cylindrical case. Liquid level detector. 2. The liquid level detector according to claim 1, wherein a mesh is disposed inside the hood. 3. A liquid level detector using a thermistor, wherein a cylindrical case closed at one end so as to allow liquid to pass through is disposed horizontally and horizontally, and a thermistor is disposed in the cylindrical case. The other end of the case is closed by a lid, a liquid hole is provided on the bottom of the cylindrical case, a flow hole is provided on an outer peripheral portion of the lid, and bubbles are formed along the inside or outside of the cylindrical case. A liquid level detector, comprising a mesh for preventing intrusion.