JPH044982Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a liquid level detection device, particularly a small liquid level detection device capable of detecting the liquid level of automobile engine oil.

Conventional technology A conventional liquid level detection device is, for example,
As shown in Japanese Patent No. 16528, it has a structure in which a permanent magnet is mounted on a float floating on the surface of engine oil, and a reed switch is mounted adjacent to this magnet. To explain this structure with reference to FIG. 3, the conventional liquid level detection device includes a case 11 forming an internal cavity 12 into which engine oil flows;
A float 13 that floats in the cavity 12 due to the buoyancy of engine oil, a permanent magnet 14 fixed to the float 13, and a permanent magnet 14 that is fixed to the float 13 when it floats.
a switch 15 that is turned on and off by movement of the switch 15;
It has a passage 16 provided in the case 11 and through which engine oil passes, and a bimetal valve 17 that opens and closes the passage 16.

When the engine is running, when the amount of engine oil in the internal cavity 12 decreases, the liquid level drops, so the float 13 floats on the engine oil.
The position of will also decrease. At this time, the reed switch 15 is switched from the on state to the off state by the movement of the permanent magnet 14, and a drop in the level of the engine oil is detected.

In this case, when the engine is started, the temperature of the engine oil is low and the viscosity is high, so the oil supplied to various parts of the engine does not quickly return to the bottom of the oil pan. Therefore, even if there is a sufficient amount of engine oil, there is a risk that the engine oil level will drop, turning off the reed switch 15, and causing the level detection device to indicate an oil shortage.

Therefore, the internal cavity 1 into which engine oil flows
A structure is adopted in which a passage 16 is provided in the case 11 forming the housing 2, and the passage 16 is opened and closed by a bimetal valve 17. As shown in FIGS. 4 and 5, the bimetallic valve 17 is formed in the shape of a curved disk as a whole, and a center hole 19 into which a mounting screw 18 is attached is in contact with a flat valve seat 20 of the case 11. It has an outer peripheral part 21. The screw 18 installed in the center hole 19 is fixed to the screw hole 23 of the boss 22 of the case 11. When the engine oil in the internal cavity 12 is heated to a certain temperature, the dotted line 17 in FIG.
As shown at a, the bimetallic valve 17 is thermally deformed and reversed by the snap action. Therefore, the outer peripheral portion 21 of the bimetallic valve 17 is separated from the valve seat 20 of the case 11 to open the passage 16. Therefore, the bimetallic valve 17 seals the engine oil into the internal cavity 12 and holds it within the internal cavity 12 until the engine oil reaches a certain temperature, thereby preventing malfunction of the liquid level display due to a drop in the liquid level when starting the engine. It can be prevented. After the engine oil reaches a certain temperature, the passage 16 is opened due to thermal deformation of the bimetallic valve 17, as described above, and the liquid level in the internal cavity 12 becomes the same as the liquid level in the oil pan.

Problems to be Solved by the Invention By the way, in the conventional liquid level detection device described above, when downsizing, the float 13 and the bimetal valve 17 are
The outside diameter was designed to be small. This method allows for some degree of miniaturization, but the bimetallic valve 17
If it is made extremely small, the oil cannot be kept tightly sealed. That is, as is clear from FIG. 4, which shows the state before the screw 18 is tightened,
In the conventional bimetallic valve 17, since it is formed to be curved as a whole, when it is fixed to the boss 22 with the screw 18, there is a gap Δl between it and the upper surface 22a of the boss 22.
is formed. When the screw 18 is tightened in this state, the gap Δl is collapsed, and the bimetallic valve 17 is deformed so that the outer peripheral portion 21 of the bimetallic valve 17 is separated from the valve seat 20 of the case 11. Therefore, if the amount of deformation of the outer peripheral part 21 is large when it is fixed with the screw 18, the outer peripheral part 21 may not come into contact with the valve seat 20, and the bimetal valve 17 may not be installed in the closed state. As is clear from FIG. 6, which shows the state in which the screw 18 is tightened, the valve seat 2
The position of the outer peripheral part 21 of the bimetallic valve 17 is shown by a dotted line, assuming that the outer peripheral part 21 is freely deformed by removing 0. The distance from the upper surface 22a of the boss 22 to the lower end 21a of the outer peripheral part 21 indicated by the dotted line is ΔH,
Assuming that the distance to the valve seat 20 is L, ΔH>L must be satisfied for the bimetallic valve 17 to be in the closed state. However, as mentioned above, when installing the conventional small bimetal valve 17, ΔH<L may occur, and in this case, a gap is created between the outer periphery 21 of the bimetal valve 17 and the valve seat 20, causing the valve to close. Unable to obtain valve status.

The object of this invention is to provide a small liquid level detection device that does not have the above-mentioned drawbacks.

Means for Solving the Problems The bimetallic valve of the liquid level detection device according to this invention has a circular flat part formed in the center with an almost infinite radius of curvature, and a curved part provided around this circular flat part. Or, it has a curved circular periphery and a hole formed in the center of the circular flat part of the bimetallic valve. The bimetal valve is fixed to the case by a mounting screw inserted through this hole.

Function: Since the bimetallic valve is formed with a circular flat part, the influence of the tightening force of the screw is removed, and even if the bimetallic valve is made smaller, its outer periphery remains in sufficient contact with the valve seat of the case.

Embodiment Hereinafter, an embodiment of this invention will be described with reference to FIGS. 1 and 2. In these drawings, parts that are the same as those shown in FIGS. 3 to 5 are designated by the same reference numerals, and explanations thereof will be omitted.

In the liquid level detection device of this invention, as shown in FIG. Circular peripheral part 3
1 is formed. Setting the radius of curvature of the circular flat portion 30 to be almost infinite means that it is sufficient that the circular flat portion 30 is substantially flat, including manufacturing errors. Further, the circular peripheral portion 31 may be a curved surface having a specific curvature, but it also means that it may be a curved surface that is a combination of a plurality of planes. When the connecting portion between the circular flat portion 30 and the circular peripheral portion 31 is formed by bending, or when the circular peripheral portion 31 is curved discontinuously, an annular bending line is generated.

When the bimetal valve 37 is fixed, the circular flat part 3
0 receives the tightening force of the screw 18, but the influence of the tightening force of the screw 18 is removed for the circular peripheral portion 31. Therefore, the bimetallic valve 37 does not deform until the outer circumferential portion 32 of the bimetallic valve 37 separates from the valve seat 20 of the case 11 when the screw 18 is tightened. Therefore, even if the bimetallic valve 37 is made smaller, the circular peripheral portion 31 of the bimetallic valve 37
The outer periphery 32 of the case 11 is in contact with the flat valve seat 22 of the case 11, and the engine oil is pumped into the inner cavity 12 until the engine oil in the inner cavity 12 reaches a certain temperature.
can be held within. When the engine oil is heated above a certain temperature, the bimetal valve 37
is reversed by the snap action caused by thermal deformation, so the outer peripheral part 32 is separated from the valve seat 20 of the case 11 to form a gap, and the liquid level of the engine oil in the internal cavity 12 is connected to the liquid level in the oil pan through the passage 16. becomes the same as

Effects of the invention As mentioned above, in this invention, a circular flat part with an almost infinite radius of curvature is formed at the center of the bimetal valve, and a curved or bent circular peripheral part is provided around this flat part. The influence of the tightening force of the screws is removed, and even if the bimetal valve is made smaller, its outer periphery is in sufficient contact with the valve seat of the case, and engine oil can be retained within the internal cavity.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a bimetallic valve used in the liquid level detection device of this invention, Fig. 2 is a partial view of the liquid level detection device with this bimetallic valve attached, and Fig. 3 is a
FIG. 4 is a partial sectional view of a conventional liquid level detection device. FIG. 4 is a partially enlarged view showing the bimetal valve installed before tightening the screw. FIG. 5 is a plan view of the conventional bimetal valve. 1 is a partially enlarged view of a conventional bimetallic valve fixed by tightening a screw. 11... Case, 12... Internal cavity, 13...
Float, 14... Permanent magnet, 15... Switch, 16... Passage, 18... Screw, 19... Hole,
20... Valve seat, 30... Circular flat part, 31... Circular peripheral part, 32... Circular outer peripheral part, 37... Bimetal valve.

Claims (1)

[Claims for Utility Model Registration] (1) A case forming an internal cavity into which engine oil flows, a float floating within the internal cavity due to the buoyancy of the engine oil, and a permanent magnet fixed to the float; A liquid level detection device including a switch that is turned on and off by the movement of the permanent magnet when the float is floating, a passage provided in the case through which engine oil passes, and a bimetallic valve that opens and closes the passage,
The bimetallic valve has a circular flat part formed with an almost infinite radius of curvature at its center, a curved or bent circular peripheral part provided around the circular flat part, and a circular flat part of the bimetallic valve. a hole formed in the center of the bimetallic valve, and the bimetal valve is fixed to the case by a mounting screw inserted through the hole. (2) The circular peripheral part of the bimetallic valve is in contact with the flat valve seat of the case, and when the engine oil in the internal cavity is heated to a certain temperature, the bimetallic valve is inverted due to thermal deformation and The liquid level detection device according to claim 1, wherein the outer peripheral portion of the bimetallic valve is separated from the valve seat of the case to open the passage.