Abstract: A liquid level detection device includes a magnet holder having a magnet housed inside a holder body in which a shaft recess is formed; a sensor housing having a shaft portion protruding from the housing body and rotatably supporting the magnet holder; a float arm whose one end is fixed to a magnet holder and whose another end is attached to a float; a Hall IC provided in the sensor housing and detecting a displacement of the magnet; an annular protrusion protruding around the shaft portion from a front surface of the housing body and facing a bottom surface of the holder body; and a recess formed on the bottom surface of the holder body and into which a protruding end of the protrusion is inserted.

Abstract: A liquid level detection device unit includes a liquid level detection device configured to detect a liquid level of liquid stored in a tank, and a fixing member fixing the liquid level detection device to inside of the tank. The liquid level detection device includes a device body, at least one terminal electrically connected to a detection unit in a housing of the device body, and a detection wire in which one end is electrically connected to an exposed part of the terminal exposed from the housing. At least one through opening is provided on an attachment surface of the fixing member so as to face the exposed part of the terminal and prevent the liquid from staying in a connection portion between the terminal and the detection wire.

Abstract: Provided is a soldering method for soldering a tip end of an electric wire to a soldering portion of a metallic terminal which allows the soldering to be performed with excellent workability. The method includes a damming structure forming step forming a damming structure at a periphery of the soldering portion to dam a solder which is supplied in a molten state with a flux to the soldering portion to keep the solder at the soldering portion, an electric wire setting step setting the tip end of the electric wire at the soldering portion ready for soldering, and a solder supplying step supplying the solder in the molten state with the flux to the soldering portion to perform the soldering.

Abstract: A liquid level detection device unit includes a liquid level detection device configured to detect a liquid level of liquid stored in a tank, and a fixing member fixing the liquid level detection device to inside of the tank. The liquid level detection device includes a device body, at least one terminal electrically connected to a detection unit in a housing of the device body, and a detection wire in which one end is electrically connected to an exposed part of the terminal exposed from the housing. At least one through opening is provided on an attachment surface of the fixing member so as to face the exposed part of the terminal and prevent the liquid from staying in a connection portion between the terminal and the detection wire.

Abstract: A liquid level detecting device includes a sensor housing, a holder held rotatably by the sensor housing, a float arm fixed to the holder, a float attached to the float arm and following a surface level of liquid stored in a tank, a magnet provided in the holder, and a Hall element detecting a displacement of the magnet. The float arm is fixed to the holder so as to extend in a direction perpendicular to a rotation axis of the holder. The sensor housing has stoppers which restrict a rotation angle range of the holder to a first rotation angle by bringing a portion of the float arm, which is positioned between a tip of the float arm and the rotation axis, into contact with one of the pair of first stoppers.

Abstract: A liquid level detecting device includes a sensor housing having a circular rotation recess, a circular holder which is fitted in the rotation recess and held rotatably by the sensor housing, a float arm, a float, a magnet, and a Hall element. The sensor housing has a lock groove and a pair of insertion holes. The holder has a pair of flanges which project in opposite directions from an outer circumferential surface of the holder and are engaged with the lock groove and prevented from coming off the rotation recess by setting the flanges opposed to the respective insertion holes, fitting the flanges into the rotation recess, and then rotating the flanges. The holder has a pair of support projections which come into contact with a bottom surface of the rotation recess.

Abstract: A liquid level detecting device includes a sensor housing, a holder, an arm fixing portion provided in the holder, a float arm, a float, a magnet provided in the holder, and a Hall element. The arm fixing portion includes a lock hole configured to receive a lock end portion of the float arm, a holding portion having a holding groove, and a retaining portion having a claw. The holding portion has a holding piece that extends parallel with a front surface of the holder and thereby forms the holding groove. The holding piece has a holding projection that projects toward the front surface of the holder so that a projection length of the holding projection increases gradually as the holding piece goes away from the lock hole.

Abstract: A liquid level detection device includes a magnet holder having a magnet housed inside a holder body in which a shaft recess is formed; a sensor housing having a shaft portion protruding from the housing body and rotatably supporting the magnet holder; a float arm whose one end is fixed to a magnet holder and whose another end is attached to a float; a Hall IC provided in the sensor housing and detecting a displacement of the magnet; an annular protrusion protruding around the shaft portion from a front surface of the housing body and facing a bottom surface of the holder body; and a recess formed on the bottom surface of the holder body and into which a protruding end of the protrusion is inserted.

Abstract: A mounting structure includes a mounting object member and a liquid level detecting device. The liquid level detecting device includes a device main body which is mounted on a mounting surface of the mounting object member and a holder which is attached to the device main body and is rotated according to a variation of a liquid level of liquid stored in a tank. The mounting object member has a pair of lock portions which lock side portions of the device main body respectively and a pair of projections. The device main body has a pair of hooks. The hooks have respective claws. The hooks are formed closer to the mounting surface in a thickness direction of the device main body than a holder movable area of the device main body.

Abstract: A liquid level detecting device includes a sensor housing, a holder which is held rotatably by the sensor housing, a float arm which is fixed to the holder, a float which is attached to a tip portion of the float arm and varies in position following a surface level of liquid stored in a tank, a magnet provided in the holder, and a Hall element which is provided in the sensor housing and detects a displacement of the magnet of the holder. The magnet is a plastic magnet in which magnetic powder and a resin are mixed. A surface of the plastic magnet is coated by a coating layer.

Abstract: A method for purifying methacrylic acid, including mixing raw material methacrylic acid and methanol; precipitating a crystal of methacrylic acid from the mixed solution; and separating the crystal and mother liquor, wherein the raw material methacrylic acid and methanol are mixed so that a concentration of methanol in the mixed liquid is 3.0 to 3.75% by mass, and the crystal of methacrylic acid is precipitated from the mixed solution in a cooling crystallization vessel.

Abstract: A method for purifying methacrylic acid, including mixing raw material methacrylic acid and methanol; precipitating a crystal of methacrylic acid from the mixed solution; and separating the crystal and mother liquor, wherein the raw material methacrylic acid and methanol are mixed so that a concentration of methanol in the mixed liquid is 3.0 to 3.75% by mass, and the crystal of methacrylic acid is precipitated from the mixed solution in a cooling crystallization vessel.

Abstract: Provided is a soldering method for soldering a tip end of an electric wire to a soldering portion of a metallic terminal which allows the soldering to be performed with excellent workability. The method includes a damming structure forming step forming a damming structure at a periphery of the soldering portion to dam a solder which is supplied in a molten state with a flux to the soldering portion to keep the solder at the soldering portion, an electric wire setting step setting the tip end of the electric wire at the soldering portion ready for soldering, and a solder supplying step supplying the solder in the molten state with the flux to the soldering portion to perform the soldering.

Abstract: A liquid level detecting device includes a sensor housing, a holder held rotatably by the sensor housing, a float arm fixed to the holder, a float attached to the float arm and following a surface level of liquid stored in a tank, a magnet provided in the holder, and a Hall element detecting a displacement of the magnet. The float arm is fixed to the holder so as to extend in a direction perpendicular to a rotation axis of the holder. The sensor housing has stoppers which restrict a rotation angle range of the holder to a first rotation angle by bringing a portion of the float arm, which is positioned between a tip of the float arm and the rotation axis, into contact with one of the pair of first stoppers.

Abstract: A liquid level detecting device includes a sensor housing having a circular rotation recess, a circular holder which is fitted in the rotation recess and held rotatably by the sensor housing, a float arm, a float, a magnet, and a Hall element. The sensor housing has a lock groove and a pair of insertion holes. The holder has a pair of flanges which project in opposite directions from an outer circumferential surface of the holder and are engaged with the lock groove and prevented from coming off the rotation recess by setting the flanges opposed to the respective insertion holes, fitting the flanges into the rotation recess, and then rotating the flanges. The holder has a pair of support projections which come into contact with a bottom surface of the rotation recess.

Abstract: A liquid level detecting device includes a sensor housing, a holder, an arm fixing portion provided in the holder, a float arm, a float, a magnet provided in the holder, and a Hall element. The arm fixing portion includes a lock hole configured to receive a lock end portion of the float arm, a holding portion having a holding groove, and a retaining portion having a claw. The holding portion has a holding piece that extends parallel with a front surface of the holder and thereby forms the holding groove. The holding piece has a holding projection that projects toward the front surface of the holder so that a projection length of the holding projection increases gradually as the holding piece goes away from the lock hole.

Abstract: A liquid level detecting device includes a sensor housing, a holder which is held rotatably by the sensor housing, a float arm which is fixed to the holder, a float which is attached to a tip portion of the float arm and varies in position following a surface level of liquid stored in a tank, a magnet provided in the holder, and a Hall element which is provided in the sensor housing and detects a displacement of the magnet of the holder. The magnet is a plastic magnet in which magnetic powder and a resin are mixed. A surface of the plastic magnet is coated by a coating layer.

Abstract: A mounting structure includes a mounting object member and a liquid level detecting device. The liquid level detecting device includes a device main body which is mounted on a mounting surface of the mounting object member and a holder which is attached to the device main body and is rotated according to a variation of a liquid level of liquid stored in a tank. The mounting object member has a pair of lock portions which lock side portions of the device main body respectively and a pair of projections. The device main body has a pair of hooks. The hooks have respective claws. The hooks are formed closer to the mounting surface in a thickness direction of the device main body than a holder movable area of the device main body.

Abstract: Provided is a crystallization method by which a highly-pure methacrylic acid crystal can be produced with high productivity. The method for purifying methacrylic acid according to the present disclosure involves using crude methacrylic acid having a maleic acid concentration of 2000 ppm by mass or less and an acrylic acid concentration of 2000 ppm by mass or less and setting the slurry temperature to ?10 to 10° C. in order to crystallize methacrylic acid. A suspension-type jacket-cooling-system crystallization vessel is used as the crystallization apparatus, and an absolute value of the difference between a crystallization temperature and a temperature of a cooling medium in the jacket is preferably 15° C. or less.

Abstract: A sensor includes: a Hall IC that outputs an electrical signal depending on a liquid level which is a detection object; a condenser used together with the Hall IC; a plurality of lead frames that includes a terminal portion to which a lead wire is connected, and a base portion to which a lead of the Hall IC is connected; and an inner member that holds the plurality of lead frames. In the inner member holding the lead frame, a space portion recessed in a concave shape is formed, and the Hall IC is accommodated in the space portion. Further, a condenser is mounted between a pair of the leads present in the space portion.