Tip-over detection sensor

Abstract

A small-sized tip-over detection sensor (10) for detecting tipping and tipping in all-directional tilting directions comprises: a hollow non-magnetic shell (12) having a concave curved surface (12a) open upward and a cover member (12b) sealing the upper end thereof in a liquid-tight manner; a cubic magnet magnetized in the longitudinal direction or a disk-shaped flat magnet magnetized in the radial direction (13), which is accommodated in a hollow portion (12c) defined by the curved surface of the shell and the cover member; a magnetic fluid (14), which is magnetically attracted to the magnetic pole portions (13a, 13b) at both radial ends of the magnet in the hollow portion; and a reed switch (15) which is disposed in the shell. A pair of reeds (15a, 15b) are integrally arranged near the central axis of the shell below; when upright, the central axis extends in the vertical direction, and the magnet is near the central axis of the curved surface of the shell due to gravity, and the magnetization direction extends in the length direction of the reed switch. Each magnetic pole portion of the magnet magnetizes the corresponding reed of the reed switch located directly below it, one reed (15a) is magnetized to the N pole and the other is magnetized to the S pole to be turned on, and when tilted from the upright state, the magnet slides along the curved surface of the shell and deviates from the central axis, and only one magnetic pole portion of the magnet is located near the central axis. The magnetic pole portion magnetizes each reed to the same pole to disconnect the reed switch.

Description

Technical Field

[0001] The present invention relates to a rollover detection sensor for detecting the rollover of various appliances such as a fan heater, a kettle, or an automatic two-wheeled vehicle. Background Art

[0002] In the past, various devices such as fan heaters and kettles were equipped with overturning detection sensors to detect overturning during use. Motorcycles were equipped with overturning detection sensors to prevent gasoline from leaking out when overturning. As such overturning detection sensors, many overturning detection sensors with simple structures and using reed switches that do not require power supply are known.

[0003] For example, Patent Document 1 discloses a tilt sensor in which a permanent magnet and a magnetic fluid are contained in a hollow non-magnetic housing having an inclined surface at the bottom, and a magnetic sensing element (reed switch) that senses the magnetic force of the permanent magnet is disposed below the bottom. In this tilt sensor, when the object whose tilt is to be detected is in an upright state, the permanent magnet is disposed at the center of the bottom of the housing, whereby one reed of the reed switch is magnetized and the contacts of the reed switch are closed.

[0004] When the object tilts from the upright position, the permanent magnet deviates from the center of the bottom surface of the housing, and the two reeds of the reed switch are not magnetized, and the contacts of the reed switch are open. Therefore, the tilt of the object can be detected by the change of the contacts of the reed switch from the closed state to the open state. Such a switch is called a normally closed type or a b contact.

[0005] If an auxiliary magnet is placed under the reed switch, the two reeds of the reed switch are magnetized to the same poles by the permanent magnet and the auxiliary magnet respectively when the object is in an upright state, and a repulsive force is generated between the two reeds, thereby maintaining the contacts of the reed switch in an open state. However, if the permanent magnet is separated from the center of the bottom surface of the housing due to the tilt of the object, only the auxiliary magnet magnetizes one reed of the reed switch, so the contacts of the reed switch are locked. Such a switch is called a normally open type or a contact.

[0006] Patent document 2 shows a tilt sensor using a reed switch. Figure 7The housing 101 made of non-magnetic aluminum has a hollow portion 102 bonded and sealed by an adhesive at the portion where the cup-shaped housing 101a and the cover 101b overlap each other. A substantially disk-shaped permanent magnet 103 with a magnetic fluid 103a coated on the surface is contained in the hollow portion 102. The housing 101 is inserted into the upper portion of a pedestal 104 made of a plastic molded product and fixed by a resin 104a. A reed switch 105 as a magnetic induction element is arranged on a printed circuit board 106, and its reed terminal is welded, and a lead 106a is led out from the printed circuit board 106. The rear cover 107 is fixed by engaging claws 107a raised from a pair of opposing sides thereof with a recess formed inside the pedestal 104. The amorphous magnetic sheet 108 attached to the top of the pedestal 104 adjusts the response angle of the tilt sensor based on its attachment position.

[0007] According to such a tilt sensor, in a horizontal state (upright state), the two reeds constituting the reed switch 105 are magnetized to the same pole by the magnetic force of the permanent magnet 103, so they repel each other and are in a disconnected state. As the tilt occurs, the permanent magnet 103 moves in the hollow portion 102 of the non-magnetic housing 101 along the tilt direction, whereby one reed of the reed switch 105 changes to the opposite pole, so that the two reeds are attracted to each other and become conductive. In this case, the reed switch 105 is acted upon by the magnetic force of the permanent magnet 103 whether it is in the disconnected state or in the connected state. Therefore, according to the tilt of the tilt sensor, no matter which state the reed switch is in, the reed switch 105 is always magnetically affected by the magnetic force of the permanent magnet.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Utility Model Publication No. 63-70017

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 1-170808 Summary of the invention

[0012] Problems to be solved by the invention

[0013] In the tilt sensor of patent document 1, since the reed switch is arranged vertically in the upright state, the tilt sensor as a whole becomes larger in the vertical direction. In addition, when the permanent magnet is arranged in the center of the bottom surface of the housing, the contacts of the reed switch are turned on by magnetizing one reed of the reed switch, and the permanent magnet moves away with the tilt, so that the contacts of the reed switch will not be disconnected by the magnetic influence of the permanent magnet. Therefore, in the on state, the other reed is not magnetized by the permanent magnet, and it is possible that the on state cannot be stably maintained, and in the off state, the reed loses its magnetic force and becomes an off state, so whether in the on state or in the off state, for example, it is possible that the on state or the off state cannot be maintained due to the influence of an external magnetic field or vibration. In addition, in the case of having an auxiliary magnet, in the off state, the two reeds are magnetized to the same poles and repel each other to stably maintain the off state, but in the on state, only one reed is affected by the magnetism and becomes the on state, so sometimes it is impossible to maintain the on state due to the influence of an external magnetic field or vibration.

[0014] In the tilt sensor of Patent Document 2, since the reed switch 105 is horizontally arranged on the printed circuit board 106 in an upright state, the tilt sensor as a whole is configured to be small in the vertical direction. In addition, each reed of the reed switch 105 is magnetically affected by the magnetic force of the permanent magnet 103 regardless of whether it is in the on state or the off state, so that the on state and the off state are stably maintained respectively.

[0015] However, the inventors of the present invention have tried to manufacture a conventional tilt sensor, changed the angle of the reed switch 105 relative to the longitudinal direction, and measured the on angle and off angle of the reed switch 105 in various tilt directions. Figure 8 The measurement results are shown.

[0016] exist Figure 8 In FIG. 1 , the length direction of the reed switch 105, i.e., the upper direction, is set to 0 degrees, and the angle in the tilt direction is taken clockwise. The line connecting the connection angle in the tilt direction is represented by a solid line, and the line connecting the disconnection angle is represented by a dotted line. Figure 8 It can be seen that the tilt in the longitudinal direction of the reed switch 105 can be detected, but the tilt in the direction orthogonal to the longitudinal direction of the reed switch 105 is not detected. Figure 8 There is a substantially undetectable blind area within the angle range indicated by the symbol A. That is, the existing tilt sensor has a problem of being unable to detect tilt or overturn in all directions.

[0017] In view of the above problems, an object of the present invention is to provide a tip-over detection sensor which is compact and capable of detecting a tilt or tip-over in all directions of tilt.

[0018] Means used to solve problems

[0019] In order to achieve the above-mentioned purpose, the tip-over detection sensor of the present invention is constructed to include: a shell, which is installed on the object whose tip-over is to be detected and is composed of a non-magnetic body, and the shell is a hollow shell having a concave curved surface and the upper surface of the curved surface is closed liquid-tightly, and the curved surface expands toward the upper side around the central axis; a magnet having magnetic poles in the length direction or a flat disk-shaped magnet magnetized in the radial direction, and the magnet is accommodated in a hollow portion divided by the curved surface and the closed upper surface of the shell; a magnetic fluid is sealed in the hollow portion and is magnetically attracted to the magnetic pole portions at least at both ends of the magnet; and a reed switch is arranged in such a way that the contact is at the center or near the center of the bottom of the shell, and when the object is upright The central axis of the shell extends in the vertical direction, and the magnet whose magnetic pole portion is covered by the magnetic fluid is located near the central axis under the action of gravity. Its magnetization direction extends approximately parallel to the length direction of the reed switch. The vicinity of the central axis is the lowest position of the curved surface of the shell. Each magnetic pole portion of the magnet magnetizes the corresponding reed of the reed switch located directly below the magnet, thereby, one reed is magnetized to the N pole and the other reed is magnetized to the S pole and attracts each other, so that the reed switch is turned on. When the object tilts from the upright state, the magnet slides along the curved surface of the shell and deviates from the central axis of the shell, and only one magnetic pole portion of the magnet is located near the central axis of the shell. Thus, the magnetic pole portion magnetizes each reed of the reed switch to the same pole and disconnects the reed switch.

[0020] According to the above structure, when the object to be detected to have overturned is in an upright state, the central axis of the shell extends in the vertical direction, and the magnet is located at the lowest position of the curved surface of the shell, i.e., near the central axis, under the action of gravity. At this time, the magnet is attracted due to the magnetic influence, so that its two magnetic poles are respectively opposite to each reed portion of the reed switch, and the direction of the magnetic poles is located at a position extending approximately parallel to the length direction of the reed switch. Therefore, the two magnetic poles of the magnet magnetize the reeds of the relative reed switches respectively, so that one reed of the reed switch is magnetized to the N pole and the other reed is magnetized to the S pole. As a result, the two reeds of the reed switch are attracted to each other, and the reed switch is turned on. At this time, the two reeds of the reed switch are magnetized by the magnetic influence of the magnet and attracted to each other, so that the turned-on state can be stably maintained, for example, it is not easily affected by external magnetic fields or vibrations.

[0021] In contrast, if the overturned object to be detected is tilted, the housing and the reed switch will also tilt accordingly, and the central axis of the housing will tilt. Therefore, as the housing tilts, the magnet in the hollow portion of the housing deviates from the central axis along the curved surface of the housing. At this time, the magnet follows the tilting direction of the housing, and its magnetic pole direction rotates relative to the central axis. As a result, one magnetic pole portion is located near the central axis of the bottom surface of the housing, and the other magnetic pole portion is separated from the central axis. Therefore, one magnetic pole portion of the magnet is located near the center of the two reeds of the reed switch facing each other near the central axis of the bottom surface of the housing, and one magnetic pole portion magnetizes the two reeds of the reed switch to the same pole. As a result, the two reeds of the reed switch repel each other, and the reed switch is disconnected. At this time, the two reeds of the reed switch are magnetized and repel each other respectively under the magnetic influence of the magnet, so that the disconnected state is stably maintained.

[0022] Here, since the bottom surface of the hollow part of the shell is divided into a concave curved surface facing upward, when the magnet moves along the curved surface due to gravity as it tilts, the magnetic fluid covering its magnetic pole portion sometimes also has a lubricating function, so that it can move smoothly along the curved surface, thereby enabling more accurate tilt detection. The reed switch is horizontally arranged in an upright state, so the overall height of the tip-over detection sensor is low and the overall structure is small.

[0023] In the present invention, since the curved surface of the housing of the tipping detection sensor is preferably formed into a hemispherical surface, it can always perform constant tilt tracking regardless of the tilt angle, and can detect the tilt more accurately. A magnet having two magnetic poles on the surface with the largest area can also be used.

[0024] The tip-over detection sensor of the present invention is preferably such that the amount of magnetic fluid is selected in such a way that the magnetic fluids magnetically attracted to the magnetic poles of the magnet in the hollow portion of the housing do not contact each other on the side or upper and lower surfaces of the magnet. Thus, the magnetic force lines coming out of one magnetic pole of the magnet and entering the other magnetic pole around the outside of the magnet do not pass through the inside of the magnetic fluid, so the magnetic force lines passing through the reeds of the reed switch located below are increased, and the reeds of the reed switch can be magnetized more efficiently to improve the sensitivity to tilt.

[0025] The tip-over detection sensor of the present invention is preferably such that the total length of the reed switch is longer than the length of the magnet. Therefore, when the tilt angle increases, the magnet moves largely along the curved surface of the housing under the action of gravity, and when the other magnetic pole portion is located near the edge of the curved surface, one magnetic pole portion is located approximately near the central axis of the curved surface, and one magnetic pole portion is opposed to the center of the reed switch to magnetize the two reeds.

[0026] Effects of the Invention

[0027] According to the present invention, it is possible to provide an extremely excellent fall detection sensor which is small in size and can detect a tilt or fall in all directions of tilt. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a cross-sectional view showing one embodiment of the fall detection sensor of the present invention.

[0029] Figure 2 Yes means Figure 1 A schematic cross-sectional view of the main parts of a tip-over detection sensor.

[0030] Figure 3 It means that it can be used for Figure 1 Diagram of the magnet shape and magnetization direction of the tip-over detection sensor.

[0031] Figure 4 It means in Figure 1 In the tip-over detection sensor, a cross-sectional view and a top view are shown of the relationship between the curved surface of the shell and the magnet when the object is tilted at angles of 0, 10, 20, and 30 degrees at 0 and 45 degrees relative to the length direction of the reed switch.

[0032] Figure 5 It is roughly expressed in Figure 1 A cross-sectional view and a top view of the tip-over detection sensor are provided for the operation at angles of 0 and 30 degrees when an object is tilted at respective tilt directions of 0, 45, and 90 degrees relative to the longitudinal direction of a reed switch.

[0033] Figure 6 Yes means Figure 1 Graph of the on angle and off angle of the tip-over detection sensor in various tilt directions.

[0034] Figure 7 It is a schematic cross-sectional view showing the structure of an example of a conventional fall detection sensor.

[0035] Figure 8 It means Figure 7 Graph of the turn-on and turn-off angles for various tilt directions of the tip-over detection sensor. DETAILED DESCRIPTION

[0036] The following is based on Figures 1 to 3 The embodiments shown are used to explain the present invention in detail.

[0037] Figure 1 and Figure 2 One embodiment of the tip-over detection sensor of the present invention is shown. Figure 3 It means that it can be used for Figure 1FIG. 1 is a diagram showing the shape and magnetization direction of a magnet of a tip-over detection sensor. As shown in the figure, the tip-over detection sensor 10 of the present embodiment includes a base 11, a housing 12, a magnet 13, a magnetic fluid 14, a reed switch 15, and a printed circuit board 16.

[0038] The base 11 is made of, for example, a resin material, preferably a non-magnetic material, and is fixed to the object 17 whose overturning is to be detected by screws (not shown). Hereinafter, the object 17 whose overturning is to be detected is simply referred to as the object 17. The base 11 has a housing accommodating portion 11a opened upward on the upper surface, and has a recessed portion 11c near the center of the housing accommodating portion 11a via a step portion 11b.

[0039] The housing 12 is made of a non-magnetic material such as a resin material or aluminum, and has a concave curved surface 12a that expands upward around the central axis O. The upper surface of the curved surface 12a is closed liquid-tightly to define a hollow portion 12c. In the present embodiment, a cover member 12b is provided to cover the upper surface, and a hollow portion 12c is defined between the curved surface 12a and the cover member 12b. The curved surface 12a is rotationally symmetrical about the central axis O, and is formed as a hemispherical surface with a curvature radius r, for example, so as to describe a gentle curve in the cross section (see Figure 2 ).

[0040] The housing 12 may also be integrally formed of the same material. In the present embodiment, the cover member 12b is formed as a plate-shaped member of a non-magnetic material, and is liquid-tightly joined to the upper end of the curved surface 12a of the housing 12 by ultrasonic welding or an adhesive. The cover member 12b is joined to the upper end of the curved surface 12a of the housing 12 after the magnet 13 and the magnetic fluid 14 are accommodated in the hollow portion 12c of the housing 12. The magnet 13 and the magnetic fluid 14 are sealed in the hollow portion 12c of the housing 12.

[0041] The housing 12 has a recessed portion 12d near the center of its lower surface. The recessed portion 12d is formed at a position corresponding to the recessed portion 11c of the base 11 when the housing 12 is fitted into the housing accommodating portion 11a of the base 11, and the recessed portion 12d has a printed circuit board 16 fitted around it, and has a second recessed portion 12e positioned in the housing 12.

[0042] The magnet 13 is a permanent magnet such as ferrite or neodymium. Figure 3 Shape shown. Figure 3 The magnet 13 shown in (A) is in the shape of a rectangular parallelepiped bar and has magnetic poles at both ends in the longitudinal direction. Figure 3 The magnet 13 shown in (B) is a rectangular shape magnetized in the thickness direction of the magnet, and two magnetic poles are formed on the surface. Figure 3 (C) is a flat disk-shaped magnet 13 magnetized in the radial direction, and has two magnetic pole faces formed on the outer peripheral surface. Figure 3 (D) is a disk-shaped magnet 13 magnetized in the thickness direction and having two magnetic poles on a plane. For example, Figure 1 The magnet 13 shown is formed into a flat disk shape, and is magnetized so that the magnetic poles 13a and 13b at both ends in the diameter direction become the N pole and the S pole, respectively. Figure 2 As shown, the outer diameter D of the magnet 13 is selected to be smaller than the curvature radius r of the curved surface 12a.

[0043] The magnetic fluid 14 is a well-known structure, and when it is accommodated in the hollow part 12c of the housing 12 together with the magnet 13, it is magnetically attracted by the magnet 13. The magnetic fluid 14 is interposed between the magnet 13 and the curved surface 12a of the housing 12, and as described later, when the magnet 13 moves along the surface of the curved surface 12a of the housing 12 as the object 17 tilts, it acts as a lubricant. The magnetic fluid is a fluid in which paramagnetic ultrafine particles of iron oxide are dispersed in materials such as isoparaffin, alkylnaphthalene, polyalphaolefin, and perfluoropolyether. The magnetic fluid can use the magnetic fluid used in vacuum seals, bearings, speakers, etc.

[0044] Here, when the magnetic fluid 14 is accommodated in the hollow portion 12c of the housing 12 together with the magnet 13, the amount and viscosity of the magnetic fluid 14 are appropriately selected so that the portions near the magnetic poles 13a and 13b at both ends of the magnet 13 do not contact each other between the two magnetic poles 13a and 13b of the magnet 13 on the side and upper and lower surfaces of the magnet 13 and act as a magnetic shield for the magnet 13. The viscosity of the magnetic fluid 14 is 30 mPa·s to 10000 mPa·s. The magnetic fluid used in the present invention is preferably 30 mPa·s to 500 mPa·s, although it also depends on the volume balance with the magnet. In the case of accelerating the tipping detection time, 30 mPa·s to 100 mPa·s is preferred. As the tipping detection sensor 10 used in an environment with vibration such as a motor vehicle, 100 mPa·s to 500 mPa·s is preferred. The viscosity of the magnetic fluid 14 can be appropriately selected according to the installation location or the operating environment of the tip-over detection sensor 10. As a result, the magnetic force lines connecting the magnetic poles 13a and 13b on the outside of the magnet 13 are prevented from passing through the magnetic fluid 14, so that the magnetic force lines on the outside of the magnet 13 that have a magnetic influence on the reed switch 15 described later increase.

[0045] The reed switch 15 is a well-known structure, and its length direction is perpendicular to the central axis O of the housing 12, and the pair of reeds 15a and 15b are arranged in a manner such that they are located near the central axis O, and are mounted on the printed circuit board 16. Figure 1As shown in FIG. 1 , the reed switch 15 is arranged so that the contact of the reed switch 15 is located at the center or near the center of the bottom of the housing 12, that is, the central area. The total length of the reed switch 15 is longer than the diameter D of the magnet 13 and is selected to be the maximum inner diameter of the hollow portion 12a of the housing 12, that is, Figure 2 The inner diameter of the upper end shown is less than 2r.

[0046] On the printed circuit board 16, a pair of leads 15c and 15d extending from both ends of the reed switch 15 are respectively welded to the contact parts 16a and 16b, and the lead wires 16c and 16d are respectively connected to the contact parts 16a and 16b. The lead wires 16c and 16d are led out to the outside through the base 11, which is not shown in the figure. The printed circuit board 16 is embedded in the second recessed part 12e of the housing 12, and the lower end of the housing 12 is embedded in the housing accommodating part 11a of the base 11, thereby being positioned and fixed relative to the housing 12. In this way, each reed 15a and 15b of the reed switch 15 is arranged near the central axis O of the housing 12.

[0047] The base 11 of the tip-over detection sensor 10 of this embodiment is fixed to the object 17 whose tip-over is to be detected by screws or the like. When the object 17 is not tipped over but is upright (upright state), the central axis O extends in the vertical direction, and the magnet 13 is located at the lowest position of the curved surface 12a of the housing 12, that is, near the central axis O, due to gravity. In this state, the magnetic poles 13a and 13b of the magnet 13 want to get closer to the reeds 15a and 15b of the reed switch 15 by magnetic attraction, so as to Figure 1 and Figure 2 As shown, the magnetic pole direction of the magnet 13 is located at a position extending substantially parallel to the longitudinal direction of the reed switch 15 .

[0048] The reeds 15a and 15b of the reed switch 15 are magnetized by the corresponding magnetic poles 13a and 13b of the magnet 13, respectively, so that the reeds 15a and 15b are magnetized to different poles and attract each other, and the reed switch 15 is turned on. At this time, the reeds 15a and 15b are magnetized by the magnetic poles 13a and 13b of the magnet 13, respectively, so that the turned-on state of the reed switch 15 is stably maintained, and it is not easily affected by external magnetic fields or vibrations, etc., so that the possibility of malfunction is eliminated.

[0049] When the object 17 falls over from the upright state, the fall detection sensor 10 also tilts at the same tilt angle as the object 17 as the object 17 tilts. Therefore, the housing 12 and the reed switch 15 tilt at the same tilt angle, but the magnet 13 and the magnetic fluid 14 in the hollow portion 12c of the housing 12 deviate from the central axis O along the surface of the curved surface 12a of the housing 12 due to gravity, and always stay at the lowest position in the vertical direction of the curved surface 12a.

[0050] Here, refer to Figure 4 and Figure 5 The operation of the magnet 13 in various tilting directions will be described. Figure 4 It means in Figure 1 In the tip-over detection sensor, when the curved surface 12a is tilted at an inclination direction of 0 degree and 45 degree relative to the length direction of the reed switch 15, the relationship between the curved surface 12a of the shell 12 and the magnet 13 when the inclination angle of the object is respectively 0 degree, 10 degree, 20 degree and 30 degree, is a cross-sectional view and a top view in each inclination direction.

[0051] The top (I) represents the upright state with an inclination angle of 0 degrees, which is the same as Figure 1 and Figure 2 The second (II) represents a case where the tilt direction is 45 degrees and the tilt angle is 10 degrees. If the curved surface 12a is tilted 10 degrees in the direction of the arrow (tilt direction 45 degrees) in the top view, the magnet 13 rotates slightly from 0 degrees toward the tilt direction to the horizontal direction, and deviates in the direction opposite to the tilt direction along the curved surface 12a. As a result, the magnetic pole portion 13b, which is the S pole of the magnet 13, approaches the reed switch 15, and its magnetic attraction force increases. On the other hand, the magnetic pole portion 13a, which is the N pole, moves away from the reed switch 15, and its magnetic attraction force decreases. Therefore, as shown in the cross-sectional view, the reeds 15a and 15b of the reed switch 15 approach the magnetic pole portion 13b of the magnet 13 and are magnetized to the same pole.

[0052] Similarly, the third (III) and the fourth (IV) represent the cases where the tilt angles are 20 degrees and 30 degrees, respectively, and the magnet 13 is offset along the surface of the curved surface 12a. As a result, the magnetic pole portion 13b of the magnet 13 remains close to the reeds 15a and 15b near the center of the reed switch 15, while the magnetic pole portion 13a moves further away from the reed switch 15, and its magnetic attraction force is further reduced. Therefore, as shown in the cross-sectional view, the reeds 15a and 15b of the reed switch 15 are magnetized to the same pole by approaching the magnetic pole portion 13b of the magnet 13, and the magnet 13 rotates in the horizontal direction in the direction opposite to the tilt direction due to the further reduction of the magnetic attraction force, and is stable in the direction of 45 degrees.

[0053] Figure 5 The figure shows the relationship between the curved surface 12a of the shell 12 and the magnet 13 when the curved surface 12a is inclined at 0 degrees, 45 degrees and 90 degrees relative to the length direction of the reed switch 15, and the object has an inclination angle of 0 degrees and an inclination angle of 30 degrees, respectively, and are a cross-sectional view and a top view in the inclination direction.

[0054] The top (I) represents the upright state with an inclination angle of 0 degrees, which is the same as Figure 1 , Figure 2 and Figure 4 (I) The same state. The second (II) represents the case of an inclination direction of 0 degrees and an inclination angle of 30 degrees. If the curved surface 12a is inclined by 30 degrees in the direction of the arrow (inclination direction of 0 degrees) in the top view, the magnet 13 does not rotate in the horizontal direction, but is offset in the inclination direction along the curved surface 12a. Thus, similarly, the magnetic pole portion 13b, which is the S pole of the magnet 13, approaches the reed switch 15 and the magnetic attraction force increases. On the other hand, the magnetic pole portion 13a, which is the N pole, moves away from the reed switch 15 and the magnetic attraction force decreases. Therefore, as shown in the cross-sectional view, the reeds 15a and 15b of the reed switch 15 are magnetized to the same pole by approaching the magnetic pole portion 13b of the magnet 13.

[0055] Similarly, the third (III) and fourth (IV) indicate a 45 degree tilt direction (with Figure 4 In the case of 90 degrees, the magnet 13 is offset along the surface of the curved surface 12a and rotates in the horizontal direction toward the side opposite to the tilting direction. As a result, the magnetic pole portion 13b of the magnet 13 remains close to the reeds 15a and 15b near the center of the reed switch 15, and the magnetic pole portion 13a is separated from the reed switch 15, and its magnetic attraction force is further reduced. Therefore, as shown in the cross-sectional view, the reeds 15a and 15b of the reed switch 15 are magnetized to the same pole by approaching the magnetic pole portion 13b of the magnet 13, and the magnet 13 is rotated in the horizontal direction to the direction opposite to the tilting direction due to the further reduction of the magnetic attraction force, and is stable in the direction of 45 degrees.

[0056] In this way, in the tip-over detection sensor 10, the magnet 13 moves along the surface of the curved surface 12a of the housing 12 in all directions of the tilt of the object 17, following the tilt direction and tilt angle. Therefore, by magnetizing the same poles as the reeds 15a and 15b near the center of the reed switch 15, the reeds 15a and 15b repel each other and the reed switch 15 is turned off. At this time, the magnetic pole 13a or 13b of the magnet 13 exerts a magnetic influence on the two reeds 15a and 15b and is magnetized, so that the off state of the reed switch 15 is stably maintained and is not easily affected by external magnetic fields or vibrations.

[0057] According to the tip-over detection sensor 10 of the present invention, it is possible to detect tilt or tip-over in all directions of tilt of the reed switch 15, which cannot be detected by the conventional tip-over detection sensor. When the reed switch 15 detects tilt or tip-over, the reed switch 15 is turned off, so that when tilt or tip-over is detected, the reed switch 15 can automatically stop the operation of the object 17. For example, in the case where the object 17 is a fan heater, a kettle or other equipment, the operation of these equipment can be automatically stopped by the reed switch 15. Since the reed switch 15 is airtightly sealed in a container such as glass, for example, it is possible to provide a tip-over detection sensor 10 that is not easily affected by the surrounding corrosive atmosphere, etc., that is, it is possible to provide a so-called environmentally resistant tip-over detection sensor 10.

[0058] The material and size of the magnet 13 are appropriately selected according to the size of the reed switch 15. The interval between the lowermost position of the curved surface 12a of the housing 12 in the upright state and the reed switch 15 is appropriately selected based on the magnetic properties and size of the permanent magnet 13 and the operating value of the reed switch 15.

[0059] Next, the results of measuring the ON angle and OFF angle in various tilt directions of the prototype of the tip-over detection sensor 10 are shown. The radius of the curved surface 12a of the housing 12 is set to A neodymium magnet with a diameter D of 5 mm and a thickness of 1 mm, which was magnetized in the radial direction, was used as the magnet 13. A reed switch RD-18B manufactured by Japan Alife (the applicant) was arranged at a position 5 mm away from the bottom of the central axis O of the curved surface 12a, and a prototype of the tipping detection sensor 10 was produced.

[0060] Using this prototype, the tip-over detection sensor was tilted in the tilt directions of 45, 90, 135, 180, 225, 270, and 315 degrees, with the longitudinal direction of the reed switch 15 being 0 degrees, and the tilt angle at which the reed switch 15 was turned off (off angle) and the tilt angle at which the reed switch 15 was turned on again (on angle) were measured. The results showed that Figure 6 The results of the measurements are shown. Figure 6 In FIG. 1 , the solid line connects the on angles in each measured value, and the dotted line connects the off angles. Based on the measurement results, it is confirmed that the off and on of the reed switch 15 are measured in all directions of the tipping detection sensor 10, and the tipping detection sensor 10 of the present invention detects tipping in all directions.

[0061] The present invention can be implemented in various ways within the scope of the present invention. For example, in the above-mentioned embodiment, the magnet 13 is exclusively formed into a flat disk shape, but it can also be a rectangular parallelepiped shape. In this case, the center of the magnet 13 is open up and down, thereby, the magnet 13 coated with the magnetic fluid 14 can move more smoothly along the surface of the curved surface 12a of the housing 12.

[0062] In the above embodiment, as an example, the curved surface 12a of the housing 12 is formed as a hemispherical surface, but it is not limited thereto and may be a smooth concave curved surface whose curvature radius changes continuously. Thus, the magnet 13 can be ensured to move smoothly along the surface of the curved surface 12a of the housing 12.

[0063] Explanation of symbols

[0064] 10… tip-over detection sensor; 11… stand;

[0065] 11a ... housing accommodating portion; 11b ... stepped portion; 11c ... recessed portion;

[0066] 12 ... housing; 12a ... curved surface; 12b ... cover member; 12c ... hollow portion; 12d ... recessed portion; 12e ... second recessed portion;

[0067] 13…Magnet;

[0068] 13a, 13b ... magnetic poles; 14 ... magnetic fluid;

[0069] 15…reed switch; 15a, 15b…reed; 16…printed substrate;

[0070] 16a, 16b ... contact portion; 16c, 16d ... lead wires;

[0071] 17 ... Overturned object (object) should be detected.

Claims

1. A tip-over detection sensor, comprising: A housing, which is mounted on the object to be detected to have fallen over and is made of a non-magnetic body, and is a hollow housing having a concave curved surface whose upper surface is sealed in a liquid-tight manner, and the curved surface expands in diameter upward around a central axis; a magnet having magnetic poles in the longitudinal direction or a flat disk-shaped magnet magnetized in the radial direction, the magnet being accommodated in a hollow portion defined by the curved surface and the closed upper surface of the housing; A magnetic fluid is sealed in the hollow portion and is magnetically attracted to the magnetic poles at at least two ends of the magnet; as well as A reed switch configured so that the contacts are at or near the center of the bottom of the housing, The curved surface of the shell is a hemispherical surface or the curved surface of the shell is a smooth concave curved surface with a continuously changing radius of curvature. When the object is upright, the central axis of the shell extends in the vertical direction, and the magnet whose magnetic pole portion is covered by the magnetic fluid is located near the central axis under the action of gravity, and its magnetization direction extends approximately parallel to the length direction of the reed switch. The vicinity of the central axis is the lowest position of the curved surface of the shell, and each magnetic pole portion of the magnet magnetizes the corresponding reed of the reed switch located directly below the magnet, thereby, one reed of the reed switch is magnetized to the N pole and the other reed is magnetized to the S pole and attracts each other, so that the reed switch is turned on. When the object is tilted from an upright position, the magnet follows the tilting direction and tilting angle and slides along the curved surface of the shell and deviates from the central axis of the shell, and only one magnetic pole portion of the magnet is located near the central axis. As a result, the magnetic pole portion magnetizes the reeds of the reed switch to the same pole, thereby disconnecting the reed switch in all-round tilting directions of the object.

2. The tip-over detection sensor according to claim 1, wherein: The curved surface of the housing is formed into a hemispherical surface.

3. The tip-over detection sensor according to claim 1 or 2, wherein: The upper surface of the curved surface is closed liquid-tightly by a cover member.

4. The tip-over detection sensor according to claim 1, wherein: A magnet having two magnetic poles on the face having the largest area of ​​the magnet is used.

5. The tip-over detection sensor according to claim 1 or 4, wherein: The amount of the magnetic fluid is selected so that the magnetic fluids magnetically attracted to the magnetic poles of the magnet in the hollow portion of the housing do not contact each other on the side surfaces or the upper and lower surfaces of the magnet.

6. The tip-over detection sensor according to claim 1, wherein: The overall length of the reed switch is longer than the length of the magnet.

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