JPH10246665A - Fuel gage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fuel gage which can enhance the measuring accuracy of a fuel volume by a method wherein an inner float which keeps a water line constant is installed inside an outer float. SOLUTION: When a fuel level F is low, a curled wire 9 shrinks, the expansion and contraction load of the curled wire 9 is small, and the water line of an outer float 11 and that of an inner float 13 become nearly identical. On the other hand, when the fuel level F is raised, the expansion and contraction load of the curled wire 9 is applied to the outer float 11, and the water line of the outer float 11 is raised. However, the inner float 13 in which a Hall IC 25 is built is moved freely inside the outer float 11 to the long direction of a support. In addition, the curled wire 9 which connects the inner float 13 to the outer float 11 is composed of only a core wire, its expansion and contraction load is small. As a result, even when the water line of the outer float 11 is moved, the water line of the inner float 13 is kept nearly constant. Thereby, it is possible to reduce a measuring error due to the expansion and contraction load of the curled wire 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel gauge, and more particularly to a fuel gauge applicable to measurement of a fuel capacity of a vehicle.

[0002]

2. Description of the Related Art Conventionally, a magnetic fuel gauge is known as a fuel gauge for measuring the fuel capacity of a vehicle.

[0003] This type has a vertical direction of 2
The two columns of soft magnetic material are placed opposite to each other, and the two magnets are arranged so that the magnetization direction is perpendicular to the longitudinal direction and opposite to each other between the upper end and the lower end of the two columns. Two magnets are arranged.

[0004] A float that floats in accordance with the fuel level is inserted into the two columns, so that the float can move only in the longitudinal direction of the column. A yoke is inserted into the element insertion portion formed inside the float so as to approach and oppose the opposing surfaces of the two columns, and a Hall IC is inserted between the yokes. Then, one end of a curl wire is connected to the terminal of the Hall IC, the lower end of the curl wire is fixed to a support, and the signal output line beyond the curl wire is drawn out of the fuel tank.
The curl wire is wound around the column to prevent the curl wire from surrounding and hindering the movement of the float.

In the magnetic fuel gauge having such a structure,
A closed magnetic path is formed by the two magnets and the two columns. By arranging two yokes in this closed magnetic path, the magnetic flux emitted from the upper magnet and the magnetic flux emitted from the lower magnet form closed magnetic paths, respectively, and the magnetic flux generated by these closed magnetic paths in the gap between the yokes. Leak in directions that cancel each other.

Here, if permanent magnets having the same shape and the same energy product are used for the respective magnets, positive and negative magnetic flux densities which change symmetrically with respect to the center position of the magnetic circuit are generated in the gap between the yokes. This change in magnetic flux density can be detected by a Hall IC that generates a voltage output proportional to the magnetic flux density. Since the Hall IC is integral with the yoke and fixed inside the float, when the liquid level of the fuel in the fuel tank changes, the float moves following the liquid level and the distance to the magnet changes. I do. Further, there is an advantage that the position of the float with respect to the support, that is, the liquid level can be detected from the output voltage of the Hall IC that moves with the float.

[0007]

However, since the curl wire has a curl shape and thus has elasticity, the elastic force increases when the curl wire elongates as the fuel level rises. . As a result, the force for pulling the float downward increases, and the float moves downward with respect to the liquid level. As a result, the position of the Hall IC with respect to the liquid level necessarily moves downward, so that there is a problem that the fuel capacity calculated based on the output of the Hall IC presents a value lower by this movement.

[0008] The present invention has been made in view of the above,
It is an object of the present invention to provide a fuel gauge that can contribute to improving the accuracy of fuel capacity measurement.

[0009]

According to the first aspect of the present invention,
In order to solve the above problem, a float that floats according to the liquid level of fuel is provided with a detecting unit that detects the position of the float, and in a fuel gauge that measures a fuel capacity according to the detected float position, A first float provided with the detection means and floating in accordance with the liquid level of the fuel, and a second float including the first float and floating in accordance with the liquid level of the fuel; The gist is to keep the draft line of the first float constant even when the draft line of the float moves.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, the first float is provided with a wire that can be extended and contracted between the detecting means and the second float in accordance with the fuel level. It is the gist to have.

[0011]

According to the first aspect of the present invention, the first float is provided with the detecting means, and the second float is configured to include the first float, and the draft line of the second float is provided. Even when the vehicle moves, the draft line of the first float is kept constant, so that it is possible to contribute to improvement in the accuracy of measuring the fuel capacity.

According to the present invention, the first float is provided between the detecting means and the second float.
Since the wire has a wire that can be expanded and contracted according to the fuel level, the load on the wire associated with the first float can be reduced, and as a result, it is possible to contribute to improving the measurement accuracy of the fuel capacity.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a magnetic fuel gauge 1 to which a fuel gauge according to an embodiment of the present invention can be applied. The fuel tank for mounting on the vehicle is
Many have a special shape in order to improve capacity efficiency, for example, some have a shape adapted to a rear seat of a vehicle. In this case, the fuel tank is thin and has an oblique shape with respect to the vertical direction. Since the magnetic fuel gauge 1 of the present embodiment is mounted on such a fuel tank, the magnetic fuel gauge 1 is mounted on the fuel tank at an angle of about 35 degrees with respect to the vertical direction.

In FIG. 1, a magnetic fuel gauge 1 includes two soft magnetic material columns 3a, 3 having a longitudinal direction extending in the vertical direction.
The magnets 5a, 5b are positioned so that the magnetization directions are perpendicular to the longitudinal direction and opposite to each other between the upper end and lower end of these two columns 3a, 3b. Are arranged respectively. The magnets 5a and 5b are, for example, 9 m
Made of SmCo magnet of mx 9mm x 10mm, 10m
It is magnetized in the direction of m. The columns 3a and 3b are made of SUS430, which is a magnetic material having high corrosion resistance, and have a length of 4 mm.
The shape is 50 mm, width 10 mm and thickness 2.5 mm.

A float 7 that floats in accordance with the fuel level F is inserted into these two columns 3a and 3b.
The columns 3a and 3b can be moved only in the longitudinal direction.

Then, one end of a curled wire 9 which has been subjected to a curl shape processing is connected to the terminal of the Hall IC formed inside the float 7 and the other end of the curled wire 9 is
a, 3b. The curl wire 9 is attached to the support 3
It is wound around a and 3b to prevent the curl wire 9 from surrounding and hindering the movement of the float 7.
Further, the signal extraction line beyond that is connected to an external fuel meter drive circuit.

Next, the internal structure of the float 7 will be described with reference to FIGS. 3 to 5 show a cross-sectional view of the float 7 taken along the line CC ′, a line DD ′, and a line EE, respectively.
'A cross-sectional view is shown. As shown in FIG. 2, the float 7 includes an outer float 11, an inner float 13, and a base 1.
5, a contact plate 17 and a wire holder 19.

Since the outer float 11 and the inner float 13 both generate sufficient buoyancy, NBR
Consists of rubber foam. The base 15 is inserted into the inner float 13 as shown in FIG.
Is fixed to the inner float 13. Also,
As shown in FIG. 4, the inner float 13 and the base 15
The pillars 3a, 3b are provided in the through holes 23a, 23b formed in
Is penetrating. In the portion sandwiched between the through holes 23a and 23b, the same SUS as the Hall IC 25 and the columns 3a and 3b is used.
430 includes yokes 27a and 27b. As shown in FIG. 5, the base 15 is provided with columns 3a and 3b.
It is made of a polyacetal resin having a very small sliding resistance in order to reduce friction with the resin.

The Hall IC 25 is a magnetoelectric conversion element that outputs a voltage proportional to the magnetic flux density, and includes a Hall element and an amplifier circuit. The Hall IC 25 has a magnetic sensing direction, and outputs a voltage proportional to the magnitude of the magnetic flux density in the horizontal direction as shown in FIG. Float 7
Can be detected with respect to the columns 3a and 3b, that is, the liquid level F.

The contact plate 17 and the wire holder 19 are both formed of polyacetal resin.
As shown in (1), they are fixed to the outer float 11 by claws 29 and 31, respectively. As shown in FIGS. 2A and 2C, the contact plate 17 and the wire holder 1
9, the outer float 11 is positioned with respect to the columns 3a, 3b by the projections 33 provided on the columns.
To prevent tilting. Thus, the vertical movement of the outer float 11 is not hindered, and the interference between the outer float 11 and the inner float 13 is prevented. As shown in FIGS. 2B and 2C, a hook 35 is provided below the wire holder 19, and after the curl wire 9 is inserted through the hook 35, the curl wire 9 is fixed with an adhesive 37. .

Next, FIG. 7 shows a cross-sectional structure of the curl wire 9. The curled wire 9 has a structure in which three core wires composed of a conductor 39 and an insulator 41 covering the periphery thereof are twisted, and a sheath 43 is provided around the core wire. The insulator 41 and the sheath 43 are made of FEP resin which has fuel resistance and whose elasticity change at room temperature and low temperature is very small. The thickness of both the insulator 41 and the sheath 43 is 0.2 mm. Between the hook 35 and the Hall IC 25, three core wires from which the sheath 43 of the curl wire 9 has been removed are exposed. These core wires are hooked on the notches 45 to be displaced to the upper portion of the wire holder 19, and the poles 3a, 3b After winding about one turn, it is connected to the terminal of the Hall IC 25. These components are housed in a case 47 to form the magnetic fuel gauge 1.

FIG. 8 shows the change characteristics of the magnetic flux density in the direction connecting the columns 3a and 3b. As shown in FIG.
It is strong near b (the polarity is different near the magnet 5a and near the magnet 5b), and becomes almost zero at the middle point. That is, since the positions of the columns 3a and 3b and the magnitude of the magnetic flux density are determined on a one-to-one basis, the Hall IC 2 that moves together with the float 7
5, the position of the float 7 with respect to the columns 3a and 3b, that is, the liquid level F can be detected.

Here, FIGS. 9 and 10 show a manufacturing process of the magnetic fuel gauge 1. First, as shown in FIG. 9A, the contact plate 17 is attached to the outer float 11.
Is inserted and fixed by the claws 29. Next, as shown in FIG. 9B, the columns 3a and 3b are inserted into the outer float 11 and the inner float 13. Next, as shown in FIG. 9C, the curled wire 9 is inserted through the hook 35 of the wire holder 19, and is fixed to the hook 35 with an adhesive 37. The length of the curl wire 9 passed through the hook 35 is such that the inner float 13 can move freely in the outer float 11 and can be wound about once around the columns 3a and 3b. Furthermore, the curl wire 9 on the side passed through the hook 35
The sheath 43 is removed to expose the three core wires.

Next, as shown in FIG.
5 is connected by soldering to the side of the curled wire 9 from which the sheath 43 has been removed. Next, as shown in FIG. 10 (e), the curl wire 9 is wound in a curl around the columns 3a and 3b, and the base float and the claws 21 and 31 of the wire holder 19 are placed on the outer float 11 and the inner float. On the 13th side, the columns 3a and 3b are inserted. Next, FIG.
(F) As shown in FIG.
3 and fixed with claws 21. Next, FIG.
As shown in (g), the wire holder 19 is inserted into the outer float 11 and fixed by the claws 31.

Next, the operation of the magnetic fuel gauge 1 will be described with reference to FIG. As shown in FIG. 11A, when the liquid level F is low, the curl wire 9 contracts.
The expansion / contraction load of the curl wire 9 is reduced, and the draft line of the outer float 11 and the inner float 13 at this time is almost the same as the draft line in a state where the curl wire 9 is not connected.

On the other hand, as shown in FIG. 11 (b), when the fuel is poured into the fuel tank and the liquid level F rises, the curl wire 9 is moved to the wire holder 19 integrated with the outer float 11.
, The elastic load of the curl wire 9 is applied to the outer float 11, and the draft line of the outer float 11 rises. However, the inner float 13 incorporating the Hall IC 25 is movable in the longitudinal direction of the columns 3a and 3b within the outer float 11, and the curl wire 9 connecting the inner float 13 and the outer float 11 is a sheath 43. Since the core wire has been removed, the expansion and contraction load is sharp. Therefore, even when the draft line of the outer float 11 moves, the curl wire 9 extends, and the inner float 13 can move in the longitudinal direction of the columns 3a and 3b.
Is kept substantially constant, and the measurement error due to the expansion and contraction load of the curl wire 9 is greatly reduced.

In this embodiment, a case has been described in which a magnetic fuel gauge is applied as a fuel gauge.
The present invention is not limited only to such a case, and is applicable to a variable resistance fuel gauge, a capacitance fuel gauge, and the like, and the same effects can be obtained.

[Brief description of the drawings]

FIG. 1 shows a magnetic fuel gauge 1 according to an embodiment of the present invention.
FIG. 3 is a diagram showing the configuration of FIG.

FIG. 2 is a magnetic fuel gauge 1 according to the embodiment of the present invention.
FIG. 4 is a diagram showing an upper cross section (a), a side cross section (b), and a lower cross section (c) of the float 7 of FIG.

FIG. 3 is a cross-sectional view of the float 7 of FIG. 2 taken along the line CC ′.

FIG. 4 is a sectional view taken along line DD ′ of the float 7 of FIG. 2;

FIG. 5 is a sectional view taken along line EE ′ of the float 7 of FIG.

FIG. 6 is a diagram showing output characteristics of the Hall IC 25;

FIG. 7 is a view showing a cross-sectional structure of a curl wire 9;

FIG. 8 is a diagram showing a change characteristic of a magnetic flux density of columns 3a and 3b.

FIG. 9 shows a contact plate 1 on an outer float 11
Before mounting (7), when the columns 3a and 3b are inserted into the outer float 11 and the inner float 13 (b), when the curl wire 9 is inserted through the hook 35 (c), the base 15 is connected to the curl wire 9 It is a figure which shows (d) after performing.

FIG. 10 shows a state where the base 15 and the wire holder 19 are attached to the inner float 13 and the outer float 11 (e), the base 15 is attached to the inner float 13 (f), and the wire holder 19 is attached to the outer float 11 (g). FIG.

FIG. 11 is a diagram illustrating a state of the magnetic fuel gauge 1 when the fuel level F is low (a) and a state (b) of the magnetic fuel gauge 1 when the fuel level F is high.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic fuel gauge 3a, 3b Post 5a, 5b Magnet 7 Float 9 Curl wire 11 Outer float 13 Inner float 15 Base 19 Wire holder 25 Hall IC

Claims (2)

[Claims] 1. A fuel gauge for detecting a float position provided on a float that floats in accordance with a liquid level of a fuel, and measuring a fuel capacity in accordance with the detected float position, wherein the float comprises: A first detecting means for detecting a level of the fuel;
And a second float enclosing the first float and floating according to the level of the fuel, wherein the draft of the first float is also drawn when the draft line of the second float moves. A fuel gauge characterized by keeping the line constant. 2. The fuel gauge according to claim 1, wherein the first float has a wire between the detection means and the second float, the wire being stretchable according to a fuel level. .