JP2003121245A - Level detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance resolution, and to reduce a size, while suppressing the number of magnetic induction elements and resistors. SOLUTION: In this level detector arranged in a circuit board (support board) 2 along a moving direction of a float 3 having a single magnet 6, and provided with reed switches (magnetic induction elements) Rsw1-Rsw3 turned on by the magnet 6, so as to detect a level of a measured object by turning on/off selectively the respective reed switches Rsw1-Rsw3 in accompaniment to moving of the float 3, a lapping area where one portion of an arranging position of the reed switch Rsw2 is arranged to be overlapped along a longitudinal direction of the circuit board 2 with respect to an arranging position the reed switch Rsw3 is provided in the circuit board 2, and the respective reed switches Rsw1-Rsw3 are arranged in the circuit board 2 to turn the reed switches Rsw3, Rsw2 on mutually when the float 3 reaches to the lapping area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of magnetic responsive elements each composed of a reed switch, and selectively operating the magnetic responsive elements with a magnet that moves with displacement of an object to be measured such as a liquid surface. The present invention relates to a level detecting device.

[0002]

2. Description of the Related Art As a level detecting device, a plurality of reed switches, which are magnetic sensitive elements, are arranged in rows on a long and narrow circuit board, and a plurality of resistors corresponding to the reed switches are provided in the circuit. The circuit board is mounted on a substrate, the circuit board is arranged in a cylindrical guide tube, and a float having a flat cylindrical magnet is arranged on the outer circumference of the guide tube, so that the object to be measured such as the liquid surface is displaced. And the float moves along the guide tube to sequentially turn on / off (operate) the reed switches arranged on the circuit board to add or subtract the resistance value of the resistor to measure the measured value. Some detect the level of an object. This level detecting device is disclosed in, for example, Japanese Patent Laid-Open No. 11-201209.

[0003]

In such a level detecting device, the reed switches are arranged in a row along the longitudinal direction of the circuit board, and the resistor bodies selected by the reed switches are arranged. The level of the object to be measured is detected by adding and subtracting the resistance value, but many reed switches and the resistors are required to improve the resolution of the detection level, and the device itself inevitably becomes large in size. There was a problem that it would end up.

In view of the above-mentioned problems, the present invention provides a level detecting device capable of reducing the number of magnetically sensitive elements and resistors while improving the resolution and downsizing.

[0005]

In order to solve the above problems, the present invention is provided with a float having a single magnet and a support substrate arranged along the moving direction of the float and operated by the magnet. A level detection device comprising at least two or more magnetically sensitive elements, wherein each of the magnetically sensitive elements selectively operates in accordance with the movement of the float to detect the level of an object to be measured. The support substrate is provided with a lap region configured such that a part of the position of the second magnetic responsive element with respect to the position of the magnetic responsive element overlaps in the longitudinal direction of the support substrate. The first and second magnetically sensitive elements are disposed on the support substrate so that the first and second magnetically sensitive elements operate with each other when the float reaches the first and second magnetic sensitive elements. The first and second detection circuits are configured by connecting the first and second resistors in series to the second magnetically sensitive element, respectively, and the first and second detection circuits are connected in parallel and A power supply unit having a reference resistance is connected in series to the first and second detection circuits.

Further, a float having a single magnet, and at least two floats arranged on the support substrate along the moving direction of the float and operated by the magnet.
A level detection device comprising one or more magnetically sensitive elements, wherein each magnetically sensitive element selectively operates in accordance with movement of the float to detect the level of an object to be measured. The support substrate is provided with a wrap region configured such that a part of the position of the second magnetically sensitive element with respect to the position of the element overlaps in the longitudinal direction of the support substrate, and the float region is provided in the lap region. The first and second magnetically sensitive elements are arranged on the support substrate so that the first and second magnetically sensitive elements operate with each other when Sensitive elements are connected in series, and first and second resistors respectively corresponding to the first and second magnetic sensitive elements are connected in series to the first and second magnetic sensitive elements and are connected in series. Reference resistance for the connected magnetically sensitive elements The power supply unit with those formed by connecting in series.

Further, the first and second magnetically sensitive elements are composed of either a normally open type or a normally closed type reed switch.

The first and second magnetically sensitive elements are normally closed reed switches.

Further, the magnetically sensitive element is disposed on the front and back surfaces of the support substrate along the moving direction of the float, and the lap region is formed at a position where the magnetically sensitive element is provided on the front and back surfaces of the support substrate. It is composed.

[0010]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing the overall structure of a level detecting device A according to an embodiment of the present invention. The level detecting device A includes a guide tube 1, a circuit board (supporting board) 2, a float 3 and This is a vertical type level detection device mainly composed of a stop collar 4 and an electric cord 5.

The guide tube 1 has a long tubular shape and constitutes a housing portion 1a for housing the circuit board 2 therein. A holding member 1b for disposing the circuit board 2 substantially perpendicular to the mounting surface of the guide tube 1 is provided at the upper end of the guide tube 1. The outer periphery of the guide tube 1 constitutes a slide guide for allowing the float 3 to move vertically.

The circuit board 2 is composed of a multi-layer board, and has reed switches Rsw (which will be described later in detail), which are magnetically sensitive elements, arranged on the front and back surfaces, and each reed switch R.
A resistor, which will be described later, corresponding to sw is provided. A wiring pattern is formed by printing on the circuit board 2, and each reed switch Rsw and each resistor are electrically connected by the wiring pattern.

The float 3 has a flat cylindrical shape, and moves vertically along the outer periphery of the guide tube 1 with the displacement of the liquid surface which is the object to be measured. The float 3 has a single ring. The magnet 6 is embedded.

The stop collar 4 has a mounting portion 4a for disposing and fixing it on a fuel tank for a vehicle, for example, and a lead-out portion 4b of the electric cord 5 is provided at the upper end portion thereof.

The electric cord 5 is for transmitting power to the circuit board 2 (reference voltages Vs and GND) and an output signal (output voltage Vout) from the circuit board 2 to the outside. It is a three-wire type electric cable for power supply and output voltage.

A level detecting device A is constituted by the above-mentioned respective parts. Next, the circuit configuration of the level detecting device according to the first embodiment of the present invention will be described with reference to FIGS.

The level detection device A includes a power supply unit 10 and
The circuit board 2 includes the level detecting section 11 and each of the sections.

The power supply unit 10 includes a first terminal 10a for applying a reference voltage Vs (for example, 5V) supplied from a constant current source circuit (not shown), and a reference resistor (divided voltage) connected to the first terminal 10a. Resistance R1 and a second terminal 10b for extracting a value obtained by dividing the reference voltage Vs by the reference resistance R1 and the combined resistance Rv of the level detection unit 11 as the output voltage Vout.

The level detecting section 11 includes first, second and third detecting circuits 11a, 11b and 11c, and each detecting circuit 1
1a, 11b, 11c are connected in series to the power supply unit 10.

The detection circuits 11a, 11b, 11c are resistors R2, R3, R for determination for determining the liquid level.
4 and a normally open reed switch Rsw connected in series with each of the resistors R2, R3 and R4.
1, Rsw2, Rsw3, and each detection circuit 1
1a, 11b, and 11c are connected in parallel to form the level detection unit 11. Then, one end of the level detection unit 11 is connected to the reference resistor R1 of the power supply unit 10, and the other end of the level detection unit 11 is connected to the GND level.

The circuit configuration of the level detecting device A described above is as follows.
This can be shown by the equivalent circuit of FIG. Therefore, each reed switch Rsw of each detection circuit 11a, 11b, 11c
1, Rsw2, Rsw3 divides the reference voltage Vs by the combined resistance Rv of the resistors R1, R2, R3 obtained by sequentially operating according to the level of the liquid level, and the reference resistance R1 of the power supply unit 10, This divided voltage is output voltage Vou
It will be taken out as t.

Next, the case of detecting the liquid level by the circuit configuration shown in the first embodiment will be described in detail with reference to FIGS. 4 and 5. FIG. 4 shows the arrangement positions of the reed switches Rsw1 to Rsw3 on the circuit board 2 according to the liquid surface levels 1 to 6 and the resistors effective when the reed switches Rsw1 to Rsw3 are turned on (operated). R2, R3
The resistance value of R4 is shown. Incidentally, R1 = 500Ω, R
2 = 50Ω, R3 = 400Ω, and R4 = 1500Ω.

That is, the liquid levels 1 to 6 in the figure are
By the magnet 6 embedded in the float 3 that moves vertically with the liquid level, the reed switch Rsw
A boundary line for selectively operating 1 to Rsw3 is shown. The liquid levels 3 and 5 include a part of the arrangement position of the reed switch Rsw2 with respect to the arrangement position of the reed switch Rsw3 and a part of the arrangement position of the reed switch Rsw1 with respect to the arrangement position of the reed switch Rsw2. , The magnet 6 that is overlapped in the longitudinal direction of the circuit board 2 and that is embedded in the float 3 causes the reed switch Rsw3
And reed switch Rsw2 and reed switch Rsw
2 and reed switch Rsw1 are simultaneously turned on (operation)
Lapping areas S1 and S provided on the circuit board 2 for
It is set so as to substantially match with 2.

In the embodiment of the present invention, the wrap areas S1 and S2 are set on the front and back surfaces of the circuit board 2. That is, the reed switch Rsw3 and the reed switch Rsw1 are provided on the surface of the circuit board 2 and the reed switch Rsw.
The sw2 is arranged on the back surface of the circuit board 2, and in the circuit board 2, a part of the arrangement position of the reed switch Rsw2 with respect to the arrangement position of the reed switch Rsw3 and a lead with respect to the arrangement position of the reed switch Rsw2. The reed switch Rsw1 and the reed switch Rsw2, and the reed switch Rsw2 and the reed switch Rsw3 are turned on at the same time by the magnet 6 which is partially overlapped with the position of the switch Rsw1 in the longitudinal direction of the circuit board 2 and is embedded in the float 3. Lap area S1,
S2 will be set.

The liquid levels 1 to 6 will be described in more detail with reference to FIG. 5 based on the above description. In the case of the liquid level 1, the reed switches Rsw1 to Rsw3 are all off and the level detector 11 is turned off. The combined resistance Rv in FIG. 2 is ∞, and the potential between the second terminal 10b and GND (hereinafter referred to as the output voltage Vout) in this case is 5v.

In case of liquid level 2, reed switch R
By turning on only sw3, the combined resistance Rv in the level detection unit 11 becomes 1500Ω, and the output voltage Vout in this case is 3.75V (Vout = Vs · Rv / (R1
+ Rv).

In case of liquid level 3, reed switch R
When the sw3 and the reed switch Rsw2 are both turned on, the combined resistance Rv in the level detection unit 11 is 31.
6Ω (Rv = R3 · R4 / (R3 + R4)), and the output voltage Vout in this case is 1.94V.

In case of liquid level 4, reed switch R
By turning on only sw2, the combined resistance Rv in the level detection unit 11 becomes 400Ω, and the output voltage Vout in this case becomes 2.22V.

When the liquid level is 5, the reed switch R
When the sw2 and the reed switch Rsw1 are both turned on, the combined resistance Rv in the level detection unit 11 is 44.
Ω, and the output voltage Vout in this case is 0.40V.

When the liquid level is 6, the reed switch R
When only sw1 is turned on, the combined resistance Rv in the level detection unit 11 becomes 50Ω, and the output voltage Vout in this case becomes 0.45V.

In FIG. 5, the combined resistance Rv is a value rounded to the first decimal place, and the output voltage Vout is a value rounded to the third decimal place.

The level detecting device A is provided on the circuit board 2 along the moving direction of the float 3 having a single magnet 6, and is provided with three reed switches Rsw1 to Rsw3 which are operated by the magnet 6. Regarding a level detection device for detecting the liquid level by selectively operating the reed switches Rsw1 to Rsw3 with the movement of the float 3, a part of the disposition position of the reed switch Rsw2 with respect to the disposition position of the reed switch Rsw3. When,
A wrap region S configured such that a part of the arrangement position of the reed switch Rsw1 and the arrangement position of the reed switch Rsw2 overlap each other in the longitudinal direction of the circuit board 2.
1, S2 are provided on the circuit board 2, and when the float 3 reaches the wrap regions S1, S2, the reed switch Rsw3 and the reed switch Rsw2, and the reed switch Rsw2.
And the reed switch Rsw1 operate together,
The reed switches Rsw3 to Rsw1 are arranged on the circuit board 2, and the resistors R4, R3 and R2 are connected in series to the reed switches Rsw1 to Rsw3, respectively.
The second and third detection circuits 11a, 11b and 11c are configured, and the first, second and third detection circuits 11a, 11b,
11c is connected in parallel to form the level detecting section 11, and the level detecting section 11 is connected in series with a power supply section 10 having a reference resistor R1.

Therefore, the three reed switches Rsw1.
Since it is possible to detect the six liquid surface levels 1 to 6 by the Rsw3 and the resistors R1 to R3, it is possible to improve the resolution of liquid surface level detection with a small number of reed switches and resistors. Further, continuous level detection is possible as compared with the conventional level detection device in which each reed switch is simply selectively operated.

Further, each reed switch Rsw1 to Rsw.
Since 3 is a normally open type, it is possible to detect the liquid level with a simple circuit configuration.

Further, each reed switch Rsw1 to Rsw.
3 are arranged on the front and back surfaces of the circuit board 2 along the moving direction of the float 3 and each reed switch Rsw.
1 to Rsw3 form the lap regions S1 and S2 at the positions where the circuit board 2 is arranged on the front and back surfaces, and increase the resolution of level detection of the liquid surface and the circuit board 2
Size of the float 3 in the moving direction and the circuit board 2
The size in the width direction can be reduced, and the size of the level detection device A itself can be reduced.

Next, the circuit configuration of the level detecting apparatus A according to the second embodiment of the present invention will be described with reference to FIGS. 6 to 8. The same or corresponding portions as those in the first embodiment described above are designated by the same reference numerals. The detailed description will be omitted.

The difference between the second embodiment of the present invention and the first embodiment is that in the circuit configuration of the level detecting device A,
Normally closed reed switches Rsw1 ', Rs
w2 ′ and Rsw3 ′ are connected in series, and the resistors R2 ′ to R3 ′ corresponding to the reed switches Rsw1 ′ to Rsw3 ′ are connected to the reed switches Rsw1 ′ to Rsw1 ′ to Rsw1 ′.
The reed switches Rsw1 ′ to Rsw3 ′ connected in series to the Rsw3 ′ are connected to the reference resistance R1 of the power supply unit 10 at one end of the series connected reed switches Rsw1 ′ to Rsw3 ′, and the resistors R2 ′ to R2.
3 ′ is connected to the GND level on the side not connected to the reed switches Rsw1 ′ to Rsw3 ′. still,
R2 ′ = 1500Ω, R3 ′ = 400Ω, R4 ′ = 50
Ω.

As shown in FIG. 7, the level detector A has six liquid level levels 1 to 6 as in the first embodiment.
The liquid levels 3 and 5 are the lap area S on the circuit board 2.
1 and S2.

Therefore, the combined resistance R when the liquid level is 1
v becomes 43Ω, and the output voltage Vout at this time is 0.40V
Becomes Further, the combined resistance Rv at the liquid level 2 is 31
It becomes 6Ω, and the output voltage Vout at this time becomes 1.94V. The combined resistance Rv for the liquid level 3 and the liquid level 4 is 1500Ω, and the output voltage Vout at this time is 3.75V. The combined resistance Rv for liquid level 5 and liquid level 6 is ∞, and the output voltage Vout at this time is
Is 5V.

Even in the circuit configuration of the level detecting device A according to the second embodiment, it is possible to set the level in four stages, and it is possible to improve the resolution by using a small number of reed switches and resistors. Further, although the same output voltage Vout is obtained at the liquid level levels 3 and 4, when the level detection device A is used as a fuel detection device for a vehicle, the output voltage Vout corresponding to the liquid level levels 3 and 4 is obtained. Is used as the intermediate data, it is possible to stabilize the display state in the display means such as the fuel gauge that does not require the importance of the intermediate data.

Further, in the level detecting device A according to the second embodiment, a normally closed reed switch R is used.
Since sw1 'to Rsw3' are used, the liquid level can be detected with a simple circuit configuration.

In each of the embodiments described above, the circuit board 2
Reed switches Rsw1 to Rsw3, Rsw on the front and back of the
Although 1'to Rsw3 'are arranged, in the present invention according to claim 1 and claim 2, at least two reed switches are provided on one side of the circuit board in the width direction of the circuit board. The circuit board is arranged in a shifted state, and the circuit board is arranged such that a part of the position of the second magnetically sensitive element overlaps with the position of the first magnetically sensitive element in the longitudinal direction of the circuit board. It may be one that forms a wrap region that constitutes it.

Further, in each of the above-described embodiments, the power supply unit 10 having the reference resistor R1 on the circuit board 2 is configured, but in the present invention, the power supply unit 10 is provided separately from the circuit board 2. It may be provided, and in such a case, the level detection unit can be further downsized.

In addition, in the circuit configuration of the above-described first embodiment, the normally open reed switch R is used.
Although sw1 to Rsw3 are used, in the present invention according to claim 1, a normally closed reed switch may be used, and the resolution of the liquid level detection level can be increased as in the first embodiment. It will be possible.

[0046]

According to the present invention, a float having a single magnet, and at least two or more magnetic sensitive elements disposed on a support substrate along the moving direction of the float and turned on or off by the magnet. A level detection device for detecting the level of an object to be measured by selectively turning on or off each magnetically sensitive element according to the movement of the float, the number of magnetically sensitive elements and resistors being suppressed. However, it is possible to provide a level detection device which can improve resolution and can be miniaturized.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a level detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration of a first embodiment of the level detecting device.

FIG. 3 is a diagram showing an equivalent circuit of the level detection device of the above.

FIG. 4 is a view for explaining level detection of the first embodiment of the level detection device of the above.

FIG. 5 is a diagram for explaining a combined resistance and output voltage in level detection according to the first embodiment.

FIG. 6 is a diagram showing a circuit configuration of a second embodiment of the same level detecting device.

FIG. 7 is a diagram for explaining level detection of the second embodiment of the same level detecting device.

FIG. 8 is a diagram illustrating a combined resistance and an output voltage in level detection according to the second embodiment.

[Explanation of symbols]

1 Guide tube 2 Circuit board (supporting board) 3 Float 6 Magnet 10 Power supply section 11 Level detection section 11a First detection circuit 11b Second detection circuit 11c Third detection circuit R1 Reference resistors R2 to R3 Resistor R2 ' ~ R3 'resistors Rsw1 to Rsw3 reed switch (magnetic sensitive element) Rsw1' to Rsw3 'reed switch (magnetic sensitive element) A level detection device S1, S2 wrap region

Claims (5)

[Claims] 1. A float having a single magnet,
At least two or more magnetically sensitive elements that are disposed on the support substrate along the movement direction of the float and that are operated by the magnets, and each of the magnetically sensitive elements operate selectively as the float moves. In the level detecting device for detecting the level of the object to be measured, a part of the disposition position of the second magnetic sensitive element with respect to the disposition position of the first magnetic sensitive element is the longitudinal direction of the support substrate. A wrap region configured to be overlapped in a direction is provided on the support substrate, and the first and second magnetically sensitive elements operate so that the first and second magnetically sensitive elements operate when the float reaches the wrap region. A second magnetically sensitive element is disposed on the support substrate, and the first and second magnetically sensitive elements are connected in series to the first and second magnetic sensitive elements, respectively.
A second resistor is connected to form first and second detection circuits, the first and second detection circuits are connected in parallel, and the first and second detection circuits are provided with a reference resistance. A level detection device comprising a power supply unit connected in series. 2. A float having a single magnet,
At least two or more magnetically sensitive elements that are disposed on the support substrate along the movement direction of the float and that are operated by the magnets, and each of the magnetically sensitive elements operate selectively as the float moves. In the level detecting device for detecting the level of the object to be measured, a part of the disposition position of the second magnetic sensitive element with respect to the disposition position of the first magnetic sensitive element is the longitudinal direction of the support substrate. A wrap region configured to be overlapped in a direction is provided on the support substrate, and when the float reaches the wrap region, the first and second magnetically sensitive elements operate to each other. Second magnetic sensitive elements are arranged on the support substrate, the first and second magnetic sensitive elements are connected in series, and first and second magnetic sensitive elements respectively correspond to the first and second magnetic sensitive elements.
Is connected in series to the first and second magnetically sensitive elements, and a power supply unit having a reference resistance is connected in series to the magnetically sensitive element group connected in series. And level detector. 3. The level detection device according to claim 1, wherein the first and second magnetically sensitive elements are constituted by either a normally open type or a normally closed type reed switch. 4. The level detecting device according to claim 2, wherein the first and second magnetically sensitive elements are constituted by normally closed reed switches. 5. The magnetically sensitive element is disposed on the front and back surfaces of the support substrate so as to be along the moving direction of the float, and the lap region is provided at a position where the magnetically sensitive element is provided on the front and back surfaces of the support substrate. The level detection device according to claim 1, wherein the level detection device is configured.