JPH0548094Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid level sensor for detecting displacement of the liquid level of liquid stored in various containers.

[Prior Art] Conventionally, for example, a storage container for storing brake oil in an automobile has been equipped with a liquid level sensor for detecting the displacement of the liquid level and notifying the driver. (See Publication No. 1973).

As shown in FIG.
a cap 33 whose bottom surface is open so as to close the cap 2;
The sensor housing 35 includes a cylindrical portion 34 extending from the cap 33 into the storage container 31 and immersed in the liquid L. Sensor housing 3
5 is provided with a housing hole 36 that opens at the upper surface of the cap 33 and extends to the lower end of the cylindrical portion 34, and a reed switch 37 is disposed within this housing hole 36. Further, a ring-shaped float 38 is loosely fitted into the cylindrical portion 34 so as to be movable up and down, and a magnet 39 for driving the reed switch 37 is attached to the inner peripheral surface of the ring-shaped float 38 .

In the liquid level sensor configured as described above, a female thread 33a is formed on the inner surface of the cap 33, and by screwing this female thread 33a into a male thread 32a on the outer periphery of the attachment port 32 of the storage container 31, the cap 33 can be opened. It is designed to be tightened and fixed to the mounting port 32.

Another type of structure for mounting the liquid level sensor to the storage container 31 is one in which the cap 33 is made of synthetic rubber, as shown in FIG. In this type, a locking recess 33b of the cap 33 is fitted into a locking protrusion 32b formed around the mounting opening 32, and the elasticity of the cap 33 causes the locking recess 33b to fit into the locking protrusion 32b. It is designed to be placed in close contact with the

[Problems to be Solved by the Invention] The conventional mounting structure as described above does not pose any particular problem when applied to a liquid level sensor of a brake oil storage container having a small capacity. However, when this mounting structure is applied to a liquid level sensor for a large-capacity storage container such as a power steering oil storage container, it is not possible to ensure sufficient sealing of the mounting portion of the cap 33 with respect to the mounting opening 32. Therefore, it has been difficult to mount the cap 33 in close contact with the mounting opening 32 to prevent liquid leakage.

In addition, in any of the conventional liquid level sensors, the float 38 is floating on the surface of the liquid L, so when the liquid level vibrates, the vibration is directly transmitted to the float 38, and as a result, ,
There was a risk that the liquid level could not be detected accurately.

The purpose of this invention is to not only ensure a reliable seal between the storage container and the cap with a simple assembly process, but also to ensure that the float, which moves up and down along the cylindrical part, is not adversely affected by the vibration of the liquid. It is an object of the present invention to provide a liquid level sensor capable of accurately detecting a liquid level while preventing the liquid from being damaged.

[Means for solving the problem] Therefore, in order to achieve the above object, the present invention has the following features:
a sensor housing including a cap that closes an attachment port of a storage container in which liquid is stored; and a cylindrical portion that extends from the cap into the storage container and is immersed in the liquid;
a switch member disposed in the cylindrical part of the sensor housing; a float fitted in the cylindrical part so as to be movable up and down and provided with a drive member for driving the switch member; an annular locking member that is externally fitted near the cap and is inserted and locked into the installation opening when installed in the storage container; a breakwater cylinder that is fixed to the cylindrical portion and covers the moving path of the float; The gist of the liquid level sensor is a liquid level sensor comprising: a biasing member that contacts a breakwater cylinder and biases the locking member toward the cap side.

[Function] When the liquid level sensor is attached to the storage container, the locking member fitted onto the cylindrical part of the sensor housing engages the locking member which is in contact with the breakwater cylinder which is also fixed to the cylindrical part. It is biased toward the cap by the biasing member. Therefore, the attachment opening of the storage container is pressed into contact with the cap via this locking member.

In addition, when the liquid level sensor is in use, the float's movement path is covered by the breakwater tube fixed to the cylindrical portion, thereby preventing the float from being adversely affected by vibrations of the liquid level outside the liquid level sensor.

[Embodiment] An embodiment in which the present invention is embodied in a liquid level sensor attached to a power steering oil reservoir tank of an automobile will be described below with reference to FIGS. 1 to 3.

1 and 3, a reservoir tank 1, which stores power steering oil (hereinafter simply referred to as oil) L, has a low, generally cylindrical mounting port 2 protruding from its upper surface. A generally circular opening 3 is provided in the upper surface of the mounting port 2, and a pair of semicircular notches 3a are formed at opposing positions.

A sensor housing 4 is inserted through the attachment port 2 of the reservoir tank 1 . As shown in FIGS. 1 and 2, the sensor housing 4 includes a cylindrical cap 5 with a low height and an open bottom.
The cap 5 is formed in a size that closes the opening 3 of the mounting port 2, and a synthetic rubber gasket 6 is attached to its lower surface. A cylindrical portion 7 extending downwardly of the reservoir tank 1 is integrally formed on the lower surface of the cap 5.

The upper end portion of the cylindrical portion 7 is a spring support portion 7a having a large diameter, and a main body portion 7b having a slightly smaller diameter than the spring support portion 7a is formed below the spring support portion 7a. A guide portion 7c having a slightly smaller diameter than the guide portion 7c is formed below the main body portion 7b, and a stopper attachment portion 7d having a slightly smaller diameter than the guide portion 7c is formed below the guide portion 7c. Note that the main body portion 7b in the cylindrical portion 7
A male thread 7e is threaded on the outer periphery of the upper end.

The sensor housing 4 has a housing hole 8 that opens on the top surface of the cap 5 and extends to the lower end of the cylindrical portion 7, and a printed circuit board 9 is disposed within the housing hole 8. The printed circuit board 9 has a detection section 9a for detecting the displacement of the liquid level of the oil L.
and a wide connecting part 9b integrally formed on the upper part of the detecting part 9a.

A reed switch 10 as a switch member having a normally open contact is attached to the lower part of the detection section 9a of the printed circuit board 9. Further, a lead wire 11 is connected to the connecting member 9b of the printed circuit board 9, and this lead wire 11 extends outside the sensor housing 4 through a rubber plug 12 fitted into the upper opening of the housing hole 8. It is connected to the connector 13. The reed switch 10 and lead wire 1
1 are electrically connected by printed wiring formed on the back surface (not shown) of the printed circuit board 9.

A ring-shaped float 15 that moves up and down following the displacement of the liquid level of the oil L is loosely fitted into the guide portion 7c of the cylindrical portion 7, and a magnet serving as a driving member is attached to the upper inner peripheral surface of the ring-shaped float 15. 16 is attached.
When the liquid level is at an appropriate level, the float 15 comes into contact with the lower end of the main body 7b of the cylindrical portion 7, and its upward movement is restricted. At this time, the magnet 16 of the float 15 faces the reed switch 10 and turns the reed switch 10 ON.
make the state Further, when the liquid level falls below the appropriate level, the magnet 16 no longer faces the reed switch 10, and the reed switch 10 is turned off.

A locking member 14 made of a metal plate is externally fitted onto the upper end of the spring support portion 7a of the cylindrical portion 7 of the sensor housing 4. This locking member 14 has a substantially annular shape with a slightly smaller diameter than the opening 3 of the mounting port 2, and has semicircular shapes at opposing positions on the outer periphery thereof,
A pair of projecting pieces 14a that can be inserted into the notch 3a of the opening 3 are integrally formed. Further, the inner circumferential portion of the locking member 14 is bent downward, and a pair of semicircular engaging recesses 14b are formed at positions offset by 90 degrees from the protrusion 14a on the inner circumferential portion. ing. Therefore, both engagement recesses 14 are attached to protrusions (not shown) provided on the outer periphery of the spring support portion 7a.
By engaging b, it is possible to unrotatably lock the locking member 14 to the spring support portion 7a.

An upper breakwater tube 17 with an open bottom surface is attached to the main body portion 7b of the cylindrical portion 7. The upper breakwater cylinder 17 is formed to have a slightly smaller diameter than the opening 3 of the mounting port 2, and is integrally formed with a cylindrical mounting part 18 on its upper surface that communicates the inside and outside of the cylinder. The upper breakwater cylinder 17 is externally fitted onto the cylindrical part 7 at the mounting part 18, and a female thread 18a formed on the inner peripheral surface of the mounting part 18 is screwed into a male thread 7e of the cylindrical part 7. In addition, on the upper outer periphery of the upper breakwater cylinder 17, a plurality of air vent holes 17 are provided to communicate the inside and outside of the upper breakwater cylinder 17.
A is transparent.

On the spring support portion 7a of the cylindrical portion 7, a compression coil spring 19 is interposed as a biasing member between the locking member 14 and the upper breakwater cylinder 17. Therefore, the locking member 14 is urged toward the cap 5 by the compression coil spring 19.

The guide portion 7c of the cylindrical portion 7 is covered with a lower wave-proof tube 20 having an open top surface. The lower breakwater tube 20 is formed to have a slightly smaller diameter than the opening 3 of the attachment port 2, and has an attachment hole 21 passing through its lower surface, into which the stopper attachment portion of the cylindrical portion 7 is attached. 7d is inserted. A stopper ring 22 is attached to the stopper attachment portion 7d that protrudes downward from the attachment hole 21, and the lower breakwater tube 20
This prevents the stopper from falling off from the stopper mounting portion 7d. As mentioned above, the lower breakwater tube 2
0 is fixed, its upper edge is in contact with the lower edge of the upper breakwater tube 17. Note that a liquid flow hole 20a is provided in the bottom of the lower breakwater cylinder 20 to communicate the inside and outside thereof.

By the way, when assembling the liquid level sensor of this embodiment, the locking member 14 and the compression coil spring 19 are fitted onto the cylindrical portion 7 of the sensor housing 4 in this order, and then the compression coil spring 19 is fitted. The upper wave-proof tube 17 is brought into contact with the upper part of the upper wave-break tube 17, and the upper wave-break tube 17 is fitted onto the cylindrical portion 7 and rotated. Then, the female thread 18a of the attachment part 18 is screwed into the male thread 7e of the cylindrical part 7, and the upper wave-proof cylinder 17 is tightened and fixed. In this way, the upper breakwater tube 17 has the function of tightening the compression coil spring 19.

After fixing the upper breakwater tube 17, the float 15 is fitted onto the guide portion 7c of the cylindrical portion 7, and in this state, the stopper mounting portion 7d is inserted into the mounting hole 21 of the lower breakwater tube 20.
Insert into. Then, the stopper ring 22 is attached to the stopper attachment portion 7d that projects downward from the attachment hole 21. Then, the lower breakwater tube 20 is prevented from falling off from the cylindrical portion 7, and the upper edge of the lower breakwater tube 20 comes into contact with the lower edge of the upper breakwater tube 17, causing the float 15 to move. Cover the route.

When attaching the liquid level sensor assembled as described above to the reservoir tank 1, grasp the cap 5 and align the protruding piece 14a of the locking member 14 with the notch 3a of the mounting opening 2 so that the liquid level sensor is attached to the reservoir tank 1. Insert the surface level sensor into the reservoir tank 1 from below. Then, when the gasket 6 attached inside the cap 5 comes into contact with the attachment opening 2, the cap 5 is turned. Then, the locking member 14 also rotates together with the cap 5, and the protruding piece 14a thereof is locked in a portion other than the notch 3a, as shown by the two-dot chain line in FIG. At this time, since the locking member 14 is urged toward the cap 5 by the compression coil spring 19, the locking member 14
The upper end of the mounting port 2 is pressed into contact with the gasket 6 through.

Therefore, when the cap 5 of the liquid level sensor of this embodiment is attached to the attachment port 2 of the reservoir tank 1, unlike the conventional one, the gap between the two is reliably sealed, and the reservoir tank 1 is completely sealed. The oil L in the tank 1 will not leak out.

Further, when the liquid level sensor is used, the float 15 moves vertically along the guide portion 7c of the cylindrical portion 7, following the displacement of the liquid surface. When the liquid level vibrates at this time, in the conventional liquid level sensor, the vibration is directly transmitted to the float 38, and the liquid level detection operation by the float 38 may be adversely affected. However,
In the liquid level sensor of this embodiment, the float 15
Since the moving path of the liquid level sensor is covered by the lower breakwater tube 20, even if the liquid surface outside the liquid level sensor vibrates as described above, the vibration is blocked by the lower wavebreak tube 20. Therefore, the float 15 can accurately detect the liquid level.

Note that the present invention is not limited to the configuration of the above embodiment, and for example, the main body part 7 of the cylindrical part 7
The thickness of the reed switch 1 can be formed to have the same thickness as the guide portion 7c, or the reed switch 1 can be formed without using the printed circuit board 9.
0 can be directly disposed in the accommodation hole 8, etc., and other modifications can be made without departing from the spirit of the invention.

[Effects of the invention] As detailed above, according to the liquid level sensor of the invention, it is possible not only to reliably seal between the storage container and the cap with a simple assembly process, but also to provide a seal between the storage container and the cap. This prevents the float, which moves up and down along the section, from being adversely affected by the vibrations of the liquid.
In addition to being able to accurately detect the liquid level, since the biasing member is brought into contact with the breakwater cylinder to bias the locking member, there is an advantage that there is no need to provide a separate member.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention; Figure 1 is a partial sectional view showing the liquid level sensor attached to the reservoir tank; Figure 2 is an exploded perspective view of the liquid level sensor. 3 are partial plan views of the attachment port of the reservoir tank, and FIGS. 4 and 5 are partial sectional views showing a state in which a conventional reservoir tank is attached to a storage container. 1... Reservoir tank as a storage container, 2...
...Mounting port, 4...Sensor housing, 5...Cap, 7...Cylindrical part, 10...Reed switch as a switch member, 14...Locking member, 15...
...Float, 16...Magnet as a driving member, 1
7... Upper breakwater tube, 19... Compression coil spring as a biasing member, 20... Lower breakwater tube.

Claims (1)

[Claims for Utility Model Registration] A cap 5 that closes the attachment port 2 of the storage container 1 in which liquid L is stored, and a cylindrical portion 7 that extends from the cap 5 into the storage container 1 and is immersed in the liquid L. a sensor housing 4; a switch member 10 disposed within the cylindrical portion 7 of the sensor housing 4; and a drive member loosely fitted into the cylindrical portion 7 to be movable up and down and for driving the switch member 10. 16
A float 15 is fitted onto the cylindrical portion 7 at a position near the cap 5, and when attached to the storage container 1, the float 15 is provided with a
An annular locking member 14 that is inserted into and is locked; Wavebreak tubes 17 and 20 that are fixed to the cylindrical portion 7 and cover the moving path of the float 15; Abutment of the wavebreak tube 17 and the locking A liquid level sensor comprising: a biasing member 19 that biases the stop member 14 toward the cap 5.