JPS62215832A - Liquid-level meter - Google Patents

Abstract

PURPOSE:To obtain a highly accurate level meter, constituted so that a rotor- shaped magnetic body having a conductive surface moves on a resistor film while contacts with said film and outputs the resistance value corresponding to the position of the float magnetically attracted to the magnetic body fixed to the float. CONSTITUTION:A magnetic body 9 and a rotary contact 7 attracts to each other with the movement of a float 8 and the rotary contact 7 moves in matching relation to the float 8. Now, when gasoline enters a fuel tank, the float 8 floats because of its low specific gravity and the permanent magnet 9 mounted to the inner hole side part of the float 8 attracts the rotary contact 7 to move on a resistor plate 6 along with the flotation of the float 8. Therefore, the connection position of the resistor plate 6 and a conductor part 9 changes along with the movement of the rotary contact 7 and the float 8. That is, a liquid level 10 is converted to a resistance value and can be taken out to the outside as a level signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Fuel gauges are used in automobiles, airplanes, and many other transportation vehicles to measure the amount of fuel remaining in a fuel tank. The majority of these fuel meters are liquid level meters that measure the height of the fuel liquid in the tank.It also measures the amount of fuel such as petroleum or organic chemical synthesis liquid stored in storage tanks. Many level meters are used for this purpose, and the present invention provides a new method for the level meters currently in use.

One of the technologies that have been used in the past is the widely used in-vehicle fuel gauge. This has a structure in which a float is suspended on gasoline in the fuel tank, and contacts mechanically linked to the float move on the winding resistance, and the output resistance value changes as the float height changes. It has become. These fuel gauges have errors ranging from a few percent to several tens of percent due to the shape of the fuel tank not being proportional to the liquid level, poor resolution due to winding resistance, and other reasons.However, recently, automobiles have been using engine-related sensors, etc. Highly accurate fuel gauges are required due to computer control and the increasing demands of vehicle users.

The liquid level meter of the present invention has a simple structure and provides a new method for realizing a fuel meter with one-to-one accuracy.

The present invention will be described in detail below regarding a level meter used as an on-vehicle fuel gauge, but it is clear that the present invention can be used not only as an on-vehicle fuel gauge but also as a wide range of general liquid level meters.

An embodiment of the present invention will be explained in detail with reference to the drawings.

Flange 1 for attachment to the fuel tank in Figure 1
has connector 2 to take out the signal to the outside.
is an obsession. A terminal 3 insulated from the flange l extends from this connector on the opposite side of the connector when viewed from the flange. A cylinder 4 is fixed to the flange l, and a rectangular tube 5 is further fixed to the inside of the cylinder 4. This rectangular tube 5 has fixed plates 14 and 15 on the cylinder 4.
is fixed.

In addition, both open ends of the square tube 5 are sealed from the outside by a lower base column 11 and an upper base seal 13 to prevent liquids such as gasoline and moisture from entering the interior.A resistance plate is provided on the inner surface of the square tube 5. 6 is the trick. The resistive plate 6 will be explained in detail in FIG. A rotating contact 7 is arranged to roll on the resistance plate 6.

A donut-shaped float 8 with a magnetic material 9 attached inside is placed on the outside of the rectangular column, and a penetrating portion near the center of the float is connected to a rectangular tube 5.
It is installed so that it passes through.

The resistance plate 6 contained inside the rectangular tube 5 has a resistance film and a conductive film formed on the surface of an insulating material such as ceramics or glass according to a certain pattern. An elongated strip-shaped film 23 in the center shown at No. 2112 is a resistive film. The lower end portion 25 of this film overlaps the conductor film 22. Rotating contact 27 (first
7) in the figure is in contact with the conductive film 24 and the resistor WA23.
Connect with. The ends 26 and 27 of the conductive film are electrical terminals to the outside, and the lead wire 12 is connected to the connector 2.
connected to.

The rotating contact 27 is connected to the resistive film 23! The resistance value measured at the terminals 26 and 27 changes by moving it while touching the H film 24. The magnetic bodies 7 and 9 are in the shape of a rectangular parallelepiped, for example, so that the magnetic bodies 7 and 9 attract each other in opposite directions, and the magnetic body 7 has a cylindrical shape. The magnetic material 9 is made of, for example, a permanent magnet of rare earth metal. For example, some rare earth metals have a product of coercive force and saturation magnetic flux of about 26 MGQe, which provides a strong attractive force.

The attractive force or repulsive force between two point magnetic poles is generally expressed by the following equation.

here 〃. :Vacuum permeability 2I・gz “Magnetization 0 strength r: distance between magnetic poles It is.

For example, samarium cobalt permanent magnet 31111
3+11111X51111 and 31φx3mm
When a combination of l soft irons arranged with their longitudinal directions parallel to each other and magnetized perpendicularly to the longitudinal direction and separated by a gap of 1.0 gw, the attraction force will be approximately 100 gw, which is a sufficiently large force. As the float 8 moves, the magnetic body 9 and the rotating contact 7 attract each other, and the rotating contact 9 moves in accordance with the float 8. 8 float is hollow,
When gasoline enters the tank, it floats to the surface because of its light specific gravity.

A permanent magnet 9 attached to the inner side of the float attracts the rotating contact 7 and moves the resistance plate 6 as the float floats. Therefore, as the rotary contact 27 in FIG. 2 moves, the connection position between the resistor part 23 and the conductor part 24 can be changed with the movement of the float 8. Therefore, it is possible to change the liquid level and resistance value and take them out as a level signal. I can do it.

Here, the relationship between the float and the rectangular tube 5 is designed so that the center of the floating force of the float 8 is at the contact surface between the float 8 and the rectangular tube 5. The surface of the square tube 5 that comes into contact with the float 8 is in contact a! Surface finishing and surface plating are applied to minimize friction.

When the float 8 moves, it receives the force of the following formula.

However, Ff: floating blade (volume of the part of the float dripping into the liquid x specific gravity of the liquid) % = Weight of the float W,: Weight of the magnetic body 9 W2: Weight of the magnetic body 7 F: Float 8 Friction at the contact surface of the rectangular tube ■ Force F2: Rotational friction force between the rotating contact 7 and the resistance plate 6 In order for the float 8 to move upward as the liquid level rises, F, ) W, + W, 10W2+F, 10F2(υ
Must.

The weight of the float is reduced by selecting a lightweight material for the volume of the hollow float and making the wall thickness appropriate.
can be made lighter. The specific gravity of gasoline is approximately 0.7
When the entire float is submerged in the liquid, it is called the maximum floating blade, and this is calculated as the product of the above volume and the specific gravity of gasoline. The actual buoyancy is the total volume of the float submerged in the liquid multiplied by the density of the gasoline.

The weight of the magnetic body 9 is proportional to its volume, and the magnetic flux density is proportional to the area facing the magnetic body 7, so the permeance coefficient is appropriately selected to make it as thin as possible and to increase the surface area. Fifth
The figure shows two examples of magnetic material configurations. 51 is a rotating contact made of a magnetic material, 52 is a flow of magnetic flux, 53 is a permanent magnet fixed to a float, and 54 is a tube wall separating both magnets. In FIG. 5(a), the magnetization is in the direction facing the permanent magnet, and in FIG. 5(b), the magnetization is in the direction parallel to the tube wall. (a)
In the case of (b), it spreads in the horizontal direction, and in the case of (b), it increases in the direction perpendicular to the tube wall.

The attraction force between magnetic bodies is small, and the attraction force between magnetic bodies is small when both magnetic bodies (fifth
53) in the figure, a large force can be obtained by using rare earth cobalt, which has a large product of coercive force and magnetic flux density.

This size is due to the fact that the mutual positions of the magnetic bodies are maintained even when a large acceleration is applied from the outside, and the frictional force between the side surface of the float where the magnetic body 9 is located and the side surface of the rectangular tube 5 caused by the attractive force. and magnetic body 7, resistance plate 6, and rotating contact 7
The sum of the rotational frictional force and the buoyancy of the float 8 is 1)
The formula must be chosen to be sufficiently consistent.

As the ml force increases, the measurement accuracy as a liquid level meter deteriorates. In order to overcome the frictional force of F10F2, the float needs to sink into the liquid by the following length 4C from the resting stateF, +F2 ≦ J) -3-Al (2) Here! = Density of gasoline S: Surface area of float If the accuracy required for a liquid level meter is ε, then (2> Equation is expressed as F, 10F2 ≦fφS−ε・l, which is satisfied. It is necessary to select the friction force etc.
Figure 4 shows a diagram in which the above liquid level meter is used as a fuel sensor in a fuel tank. to read. 31 as shown in Fig. 3 for the positional deviation of the rotating contact in Fig. 2.
, 36 changes.

Although the present liquid level meter as a fuel gauge has been described above, the present invention is applicable not only to fuel gauges but also to all types of liquid level gauges, and is highly accurate, has a simple structure, and is an economically effective liquid level meter for industrial use. A level meter is obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the device according to the present invention, FIG. 2 is an enlarged front view of a portion of FIG. 1, FIG. 3 is an equivalent circuit diagram of FIG. 2, and FIG. FIG. 5 is a diagram illustrating a part of the magnetic circuit in FIG. 1, showing an example of how the device is mounted. Patent applicant Kubotek Co., Ltd. 1st cause 2nd 凰茅 + 8 0su (-b) 5th month

Claims (1)

[Claims] A rotating body-shaped magnetic body whose surface is conductive at least moves on the resistive film while being in contact with the magnetic body, and its position with the magnetic body changes the floating position of the float due to the magnetic attraction force with the magnetic body fixed to the float. A liquid level meter that is held and outputs a resistance value corresponding to the float position.