JPH03215715A - Liquid level sensor - Google Patents

Abstract

PURPOSE:To reduce the size of the sensor and to improve the accuracy and durability by providing a rotational angle decreasing mechanism between a float arm and a contact. CONSTITUTION:A float 2e moves up and down with a liquid level and when a float arm 2c sways through a support shaft 2b within a range of a slide angle theta3=110 deg., the angle of rotation is reduced to half through a small-diameter gear 3 and a large-diameter gear 5 which constitute the rotational angle decreasing mechanism 6 and a contact arm 7 sways through a support shaft 4 within a range of a sway angle theta4=55 deg.. This swaying causes the contact 2f on the contact arm 7 to move on a resistance body 2d and the resistance value varies to a value corresponding to the liquid level, so that the liquid level is detected. Further, a signal line is connected to the resistance body 2d and contact 2f and the signal line is led out of a fuel tank through the opening part of a container. Consequently, the sensor is reduced in size and improved accuracy and durability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid level sensor, which is particularly attached to a fuel tank of a vehicle that uses liquid fuel such as gasoline or diesel oil to detect the remaining amount of fuel. This relates to a liquid level sensor used for

[Conventional technology]

Conventionally, as this type of liquid level sensor, Figs.
The configuration shown in Figure 0 was used.

Level sensors used in fuel tanks of vehicles such as passenger cars generally have the configurations shown in FIGS. 5 and 6. FIG. 5 is a side view showing the positional relationship between the level sensor and the fuel tank, and FIG. 6 is an enlarged view of the level sensor main body.
is opened, and the sensor main body 2 is attached to this opening 1a. As shown in FIG. 6, the sensor body 2 includes a support 2a, a float arm 2C swingably supported on the support 2a by a spindle 2b, and a resistor 2d formed on the support 2a. It consists of a float 2e attached to the tip of the float arm 2c, and a contact 2f fixed to the support shaft 2b of the float arm 2c.

In this level sensor, float 2e is caused by fluctuations in the liquid level.
When the flow arm 2c moves up and down, the arm 2c swings within a predetermined angular range around the fulcrum 2b.

Due to this rocking, the contactor I-2f slides on the resistor 2d, and when the resistance value of the resistor 2d changes, a sensor circuit (not shown) detects this and outputs a level signal indicating the amount of liquid level fluctuation. It can be taken out.

In the above level sensor, the resistor 2d is a wire-wound resistor with a coil wound around an insulating substrate, but since the insulating substrate is a flat plate, the coil does not shift even when the contact slides, and the coil is in contact with the coil in the liquid. Because of this contact, metal abrasion powder generated by friction is washed away with the liquid, preventing acceleration of wear and providing good sensor accuracy and durability. Furthermore, since the resistor substrate is flat, a thick film resistor can be used as the resistor instead of a coil, thereby further improving sensor accuracy.

On the other hand, the level sensors shown in FIGS. 7 and 8 are of a type used in deep fuel tanks of large vehicles such as trucks and dump trucks. Figure 7 is its side view, Figure 8 is the 7th
It is a sectional view taken along the line A-A in the figure, and the sensor main body 2 has a container l.
The support body 2g extends down to the middle part of the support body 2g.
A float arm 2c is swingably attached to the lower end of the float arm 2c, and the swinging motion of the float arm 2c is converted into a rotational motion that rotates a rotating shaft 2h disposed within the support body 2g by a rotation conversion mechanism using gears (not shown). A contact I-2f fixed to the rotating shaft 2h at the upper end of the support 2g is made to slide on the curved resistor 2d.

Float 2e and float arm 2c due to fluctuations in the liquid level.
When the rotary shaft 2h swings, the rotating shaft 2h rotates and rotates the contact 2f at its upper end, thereby changing the contact position between the contact 2f and the resistor 2d. Therefore, like the level sensor described above, fluctuations in the liquid level can be detected by the sensor circuit.

This type of level sensor is suitable for detecting the liquid level in a deep container because the swinging axis of the float arm 2C is located in the middle of the container 1, so the swinging angle of the float arm can be made large. ing.

Figures 9 and 10 show modified examples of the level sensor for the deep-bottomed container, and the rotating shaft 2h is similar to the example in Figures 7 and 8.
Rather than using a resistor provided outside the container, the swing of the float arm 2c is directly detected by a resistor 2d placed inside the container 1. In this type, like the level sensor explained in FIGS. 5 and 6, the contact between the coil and the contact is made in the liquid, so the coil,
Contacts have excellent wear resistance.

[Problem to be solved by the invention]

By the way, as mentioned above, since the depth of the container is small in the level sensor for a shallow container, the swing angle θ1 of the float arm can be relatively small (for example, 55 degrees). Types with a coil wound around them or types with a resistor coated on a substrate are used, and it is possible to obtain level sensors with relatively high accuracy using these types. Since the swing angle θ2 of the arm is large (for example, 110 degrees), the coil must be placed on a curved substrate as shown in FIGS. 8 and 9, which inevitably leads to insufficient accuracy. I don't get it.

Therefore, it is possible to use a thick film resistor or a flat coil resistor, but as shown in Fig. 11, in the case of a swing angle of 110 degrees, if the swing fulcrum is the same, the swing angle is 55 degrees. Since the size of the thick film resistor is much larger than in the case of the conventional case, as shown by the two-dot chain line, it is difficult to insert and attach it into the container.

Of course, it is possible to obtain a contact point on a small thick-film resistor by reducing the swing radius of the float arm, but in that case, the trajectory of the contact movement on the thick-film resistor will have a large curvature. Therefore, there is a problem that a desired change in resistance value cannot be obtained.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide a liquid level sensor suitable for deep-bottom containers that is small in size and has excellent accuracy and durability.

[Means to solve the problem]

In order to solve the above problems, a liquid level sensor made according to the present invention includes a float that moves up and down according to fluctuations in the level of liquid stored in a container, and a float that is supported at one end and whose other end is supported. It is equipped with a float arm that is swingably mounted in a container, a contact that is moved by the swing of the float arm, and a resistor that the contact is in sliding contact with. and a liquid level sensor in which the liquid level is transmitted to a contact via a float arm, and the contact is moved on a resistor to detect the liquid level as a change in resistance value, between the float arm and the contact. It is characterized by the inclusion of a rotation angle reduction mechanism.

[For production]

In the above configuration, the rotation angle reducing mechanism drives the contact at a small rotation angle with respect to the float arm having a large movement angle, thereby making it possible to obtain a desired change in resistance value on a small resistor.

[Example] Embodiments of the present invention will be described below based on the drawings.

1 to 3 show a first embodiment of a liquid level sensor according to the present invention, and show the front, side, and back sides of the level sensor body, respectively.

In FIGS. 1 to 3, the level sensor main body 2 is attached to the intermediate part of the container by a shaft (not shown), as in the conventional example shown in FIG. Shaft 2b, float arm 2c, resistor 2d,
It has a float 2e and a contact 2f.

A small diameter gear 3 is formed concentrically on the support shaft 2b that swingably supports the float arm 2C.
is meshed with a large-diameter gear 5 formed concentrically with the other support shaft 4 of the support body 2a.

The small diameter gear 3 and the large diameter gear 5 constitute a rotation angle reducing mechanism 6, and in this embodiment, the gear ratio of the small diameter gear 3 and the large diameter gear 5 is set to 1=2, and the rotation angle of the support shaft 2b is A rotation of half the rotation angle is transmitted to the support shaft 4. One end of a contact arm 7 is fixed to this large-diameter gear 5, and a contact 2r is formed at the other end of the contact arm 7 to slide into contact with a resistor 2d fixed to a support 2a.

With the above configuration, the float 2e moves up and down according to the liquid level, and the float arm 2C moves at a sliding angle θ about the support shaft 2b.
= 110 degrees, the rotation angle is reduced to 1 by the small diameter gear 3 and the large diameter gear 5 that constitute the rotation angle reduction mechanism 6.
/2, and the contact arm 7 swings about the support shaft 4 within a range of swing angle θ4=55°. This swing causes the contact 2f on the contact arm 7 to move to the resistor 2d.
The resistance value changes to a value corresponding to the liquid level, and the liquid level is detected. Although not shown, a signal line is connected to the resistor 2d and the contact 2f, and this signal line is led out of the fuel tank through the opening of the container.

FIG. 4 is a rear view showing a second embodiment of the liquid level sensor according to the present invention, in which a link connection is used as the rotation angle reducing mechanism 6 instead of a gear connection.

That is, as shown in the figure, a pin 8 is provided on the back surface near the base end of the float arm 2C, and a link 9 is fixed to the support shaft 4 of the other contact arm 7 on the back side of the support body 2a. The bottle 8 is engaged with the elongated hole 9a.

With this configuration, when the float arm 2c swings, the pin 8 in the elongated hole 9a comes into contact with the inner wall of the elongated hole 9a, causing the link 9 to swing around the support shaft 4. At this time, the pin 8 in the elongated hole 9a Slide on the inner wall. Now, the distance Ll between the support shaft 2b and the support shaft 4,
Distance Lt between support shaft 2b and pin 8, long hole 9 relative to support shaft 4
By appropriately setting the position of a, etc., the float arm 2
The swing angle θ4 of the contact arm 7 with respect to the swing angle θ
can be attenuated to 1/2, and the same effect as in the first embodiment can be obtained. In addition, in the illustrated embodiment,
L. The relationship between L2 and L2 changes depending on the rotation angle, and the reduction ratio increases when the liquid level is high and low, and decreases when the liquid level is at an intermediate level.
When d has a linear resistance characteristic, an effect is obtained in which the change in sensor output increases when the liquid level is at an intermediate level.

〔effect〕

As explained above, according to the present invention, since the rotation angle reducing mechanism is interposed between the float arm and the contact, it is possible to convert the large swing angle of the float arm into a small contact circuit. To obtain a level meter that is compact, has excellent durability, and has high accuracy by making it possible to use a thick film resistor or a small flat coil resistor even in a deep-bottomed container, thereby obtaining a desired change in resistance value. It is something that can be done.

[Brief explanation of drawings]

1 is a front view showing a first embodiment of the liquid level sensor according to the present invention; FIG. 2 is a side view of the sensor shown in FIG. 1; FIG. 3 is a rear view of the sensor shown in FIG. 1; Figure 5 is a rear view showing a second embodiment of the liquid level sensor according to the present invention, Figure 5 is a schematic structural diagram of a conventional liquid level sensor for shallow bottom containers, and Figure 6 is the liquid level of Figure 5 A front view of the sensor body, Fig. 7 is a schematic structural diagram of a conventional liquid level sensor for a deep-bottom container, Fig. 8 is a sectional view taken along line A-A in Fig. 7, and Fig. 9 is a diagram of another conventional deep-bottom liquid level sensor. A schematic structural diagram of a liquid level sensor for a container; FIG. 10 is an enlarged view of the main part of the sensor of FIG. 9; and FIG. 11 is an explanatory diagram of the rotation locus of the contact relative to the thick film resistor. 1... Container, 2... Level sensor body, 2a...
Support body, 2c...Float arm, 2d...Resistor, 2e...Float, 2f...Contact, 6...
・Rotation angle reduction mechanism. 1st mouth l' 2nd figure 3rd figure 4 figure 8 figure 9

Claims (1)

[Scope of Claims] A float that moves up and down in response to fluctuations in the level of liquid stored in a container; a float arm that supports the float at one end and is swingably attached to the container at the other end; It is equipped with a contact that is moved by the swinging of the float arm, and a resistor that the contact is in sliding contact with. A liquid level sensor that moves on a resistor and detects the liquid level as a change in resistance value, characterized in that a rotation angle reducing mechanism is interposed between the float arm and the contact. Liquid level sensor.