JP2012225800A - Liquid level detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detection device capable of downsizing a fixing structure of a holder for holding a float arm.SOLUTION: The liquid level detection device including a contact member 32 sliding on a circuit board 31 due to displacement of a float arm 2 attached to a float 1 and a case 6 for storing the circuit board 31 and the contact member 31 also includes: a first holder 4 including holding parts 41a, 41b for holding the float arm 2 and a rotary shaft 42; a bearing part 610 rotatably pivoting the rotary shaft 42 and arranged in the case 6; a second holder 5 for holding the contact member 32; a welding protrusion 43 attached to the end part of the rotary shaft 42 so as to be combined with the second holder 5; and a combining hole part 51 formed on the second holder 5 and combined with the welding protrusion 43: and is configured by welding and fixing the welding protrusion 43 of the first holder 4 and the combing hole part 51 of the second holder 5.

Description

  The present invention includes a float arm that converts a vertical motion associated with a displacement of the liquid level of the float into a rotational motion, and a detection unit (sensing unit) that detects the liquid level along with the rotational motion of the float arm. The present invention relates to a liquid level detection device, and more particularly to a liquid level detection device characterized by a fixing structure of a float arm and a holder that holds a part constituting a detection unit.

  As a conventional liquid level detection device, a float arm that rotates according to a change in the liquid level, a detection unit that outputs a remaining amount signal indicating the remaining amount of the liquid level in accordance with the rotation operation of the float arm, It is equipped with. The detection unit includes a resistor on the circuit board and a contact member (sliding contact) that slides on the resistor as the float arm rotates.

  The float arm and the contact member (sliding contact portion) are configured such that a holder having the contact member (sliding contact portion) is fixed to the shaft of a connecting portion holding the other end of the float arm by press-fitting or the like. Thus, the float arm and the contact member (sliding contact portion) are configured to be interlocked. (For example, see Patent Document 1)

JP-A-6-43008

  As described in Patent Document 1, in recent years, from the standpoint of environmental problems, there is an increasing demand for using high-concentration alcohol fuel as a vehicle fuel. When high-concentration alcohol fuel is used, Since the resistor and contact member (sliding contact part) are immersed in the fuel liquid, the corrosion of the resistor and contact member (sliding contact part) becomes significant, and the liquid level is accurately determined. There is a problem that it cannot be detected. In consideration of this point, the detection portion composed of the circuit board and the contact member (sliding contact portion) is housed in a sealed state by a case.

  However, in order to secure a contact area between the holder and the shaft portion of the float arm in order to secure the holder to the shaft portion of the float arm by means such as press fitting, the conventional liquid level detection device The thickness required a large thickness in the rotation axis direction of the float arm.

  For this reason, there has been a problem that it is difficult to reduce the size of the holder in the rotation axis direction. Moreover, in the liquid level detection apparatus which accommodated the detection part (sensing part) in the sealed case, there existed a problem of affecting the size of a case.

  That is, if the liquid level detection device becomes thicker or larger, problems such as difficulty in entering the fuel tank may occur when the liquid level detection device is inserted into the fuel tank. It has been desired to reduce the size of the apparatus.

  In view of the above-described problems, an object of the present invention is to provide a liquid level detection device capable of reducing the size of a fixing structure of a holder that holds a float arm.

  In order to solve the above-described problems, the present invention provides a float that floats on a liquid surface, a float arm that is displaced by the float, a circuit board that includes a resistor, and the displacement of the float arm. In a liquid level detection device comprising a contact member (sliding contact portion) that slides on a circuit board, and a case that houses the circuit board and the contact member (sliding contact portion), the float arm is held. A first holder having a holding portion and a rotating shaft, a bearing portion that rotatably supports the rotating shaft and is provided in the case, and holds the contact member (sliding contact portion) and the rotating shaft A second holder fixed to the rotary shaft and rotated together with the rotary shaft, provided at the end of the rotary shaft to be connected to the second holder (welding protrusion), provided on the second holder, The coupling hole provided in the second holder by welding the welding projection provided on the first holder, the coupling hole provided on the first holder. It is a liquid level detection device characterized by welding and fixing a part.

  By comprising in this way, the length in the axial direction of a rotating shaft can be set short by providing the holding | maintenance part which hold | maintains a float arm in a 1st holder, and the rotating shaft used as a rotation spindle separately. Therefore, it is possible to reduce the thickness of the liquid level detection device, and the fixation by welding between the first holder that holds the float arm and the second holder that holds the sliding contact portion can be firmly held.

  2. The liquid level detection device according to claim 1, wherein the first holder and the second holder are formed of resin materials having different color tones. (Claim 2)

  By comprising in this way, it can be identified easily whether the assembly position of each component by the welding state of the welding projection of the 1st holder and the joint projection of the 2nd holder is favorable. .

  The first holder is provided with a positioning portion at the boundary between the rotating shaft and the welding projection, and the second holder is provided with an alignment portion that engages with the positioning portion. The liquid level detection device according to claim 1 or 2, wherein the liquid level detection device is a liquid level detection device. (Claim 3)

  With this configuration, the assembly position of the first holder and the second holder can be determined in a predetermined state by the positioning portion and the alignment portion, whereby the resistor provided on the circuit board and the plurality of resistors are arranged. Can be assembled and held without any displacement of the set position with the contact member (sliding contact part) provided in the second holder, and can send out a stable liquid level detection signal. it can.

  The liquid level detection device according to any one of claims 1 to 3, wherein at least a part of the case is formed of a transparent material. (Claim 4)

  With such a configuration, it is possible to determine the assembled state of each holder from the outside, and it is possible to satisfactorily determine whether or not the state of welding after assembly is appropriate.

  In the present invention, a float that floats on the liquid surface, a float arm that is displaced by the float, a circuit board that includes a resistor, and a contact member that slides on the circuit board as the float arm is displaced (sliding contact) Part), a liquid level detection device comprising a case for housing the circuit board and the contact member (sliding contact part), a first holder comprising a holding part for holding the float arm and a rotating shaft; A bearing portion rotatably supported on the rotating shaft and holding the contact member (sliding contact portion), and a second holder fixed to the rotating shaft and rotating together with the rotating shaft; A welding projection provided at the end of the rotary shaft for coupling with the second holder, and a coupling provided on the second holder and coupled with the welding projection of the first holder A hole, and the welding protrusion provided on the first holder is welded and fixed to the coupling hole provided on the second holder by welding. By separately providing the holding part that holds the float arm and the rotating shaft that serves as the rotation support shaft, the axial length of the rotating shaft can be set short, so the liquid level detection device can be made thinner. The first holder holding the float arm and the second holder holding the contact member (sliding contact portion) can be firmly fixed by welding, thereby achieving the intended purpose. can do.

It is a front view of the liquid level detection apparatus which concerns on the 1st Embodiment of this invention. 2 is a cross-sectional view taken along line AA in FIG. 3 is a cross-sectional view taken along line BB in FIG. FIG. 4 is an exploded perspective view showing a main part of each holder. FIG. 5 is an exploded perspective view showing a part of FIG. 4 in cross section.

  Hereinafter, a first embodiment to which the present invention is applied will be described with reference to the accompanying drawings.

  The liquid level detection device F of the present invention includes a float 1, a float arm 2 that holds the float 1, a detection unit (sensing unit) 3 for detecting the amount of liquid, a first holder 4 that holds the float arm 2, and a detection unit. 3 includes a second holder 5 that holds a part of the components 3 and a case (main body) 6 that houses the detector 3.

  The float 1 floats on the liquid surface and is displaced with the displacement of the liquid surface.

  The float arm 2 is made of metal, and the float 1 floating on the liquid surface is attached and held at one end, and the first holder 4 is held at the other end. At this time, the end 2b of the float arm 2 is bent in a substantially L shape with respect to the main portion 2a of the float arm 2, and the bent end 2b and the main portion 2a adjacent to the end 2b are located. Two portions are provided so as to be held by holding portions (mounting portions) 41 a and 41 b provided in the first holder 4.

  The float arm 2 fluctuates according to the fluctuation of the liquid level, and rotates about the rotation shaft 42 provided in the first holder 4.

  The detection unit (sensing unit) 3 outputs a remaining amount signal indicating the remaining amount of the liquid surface as the float arm 2 rotates, and in this embodiment, the circuit board 31 and the contact member 32 It is configured.

  The circuit board 31 includes a ceramic substrate, which is an insulating base material, and a resistor (not shown) and a plurality of sliding electrodes. The plurality of sliding electrodes are each electrically connected to the resistor independently. The contact member 32 slides on the plurality of sliding electrodes.

  The contact member 32 is made of a conductive metal, has a plurality of contact points, and the base side of the contact member 32 is fixedly held by the second holder 5.

  The first holder 4 is formed of a synthetic resin and has two holding portions that hold the end 2b of the float arm 2 and the main 2a of the float arm 2 adjacent to the end 2b. 41a and 41b are provided, and a rotation shaft 42 that serves as a rotation support shaft of the float arm 2 is provided.

  In addition, a welding projection 43 provided for coupling to the second holder 5 is provided at the end of the rotation shaft 42 in the first embodiment, and the boundary between the rotation shaft 42 and the welding projection 43 is provided. Is provided with a positioning portion 44. An annular packing 7 is disposed so as to surround the root of the rotating shaft 42.

  The second holder 5 is formed of a synthetic resin, and fixes and holds the base side of the contact member 32 as described above.

  The second holder 5 is provided with a coupling hole 51 that is coupled to the welding projection 43 of the first holder 4, and an alignment portion 52 that is engaged with the positioning portion 44 of the first holder 4. Yes.

  The case 6 includes a first case 61 having a frame shape and a second case 62 having a lid shape. The case 6 houses the circuit board 31 and the contact member 32 constituting the detection unit 3 in a sealed state.

  The first case 61 is formed of a light-shielding synthetic resin material that does not transmit light, for example, a black resin material. The first case 61 is provided with a bearing portion 610 that rotatably supports the rotary shaft 42 provided in the first holder 4. The bearing portion 610 is a through hole.

  The first case 61 is integrally formed with a female connector 611 formed of a recess. The first case 61 is provided with a terminal 612 so as to be exposed from the connector portion 611. Further, the other end of the terminal 612 is exposed to the inside of the first case 61 and is electrically connected to the circuit board 31 by solder (not shown) or the like. The terminal 612 is electrically connected to a male connector (not shown), and outputs a signal output from the detection unit 3 to the outside.

  The second case 62 is formed of a transparent synthetic resin material that transmits light so that the inside can be seen, for example, a transparent resin material.

  Further, the first case 61 is provided with a storage portion 613 for storing the packing 7 attached to the rotating shaft 42. The storage portion 613 is formed by a cylindrical wall portion, and is provided on the outer wall surface side of the first case 61 so as to surround the opening of the bearing portion 610 formed of a through hole.

  The packing 7 serving as a sealing member is mounted between the rotating shaft 42 and the storage portion 613. In this embodiment, the packing 7 is formed of a fluorine-based rubber material, has a ring shape (annular shape), and has a V-shaped cross section, for example. The cross-sectional shape of the packing 7 is a generally used O-ring shape (round cross-sectional shape), an X-shaped cross-sectional shape, or a shape and size arranged in the storage portion 613. What is necessary is just to select suitably by etc. Thus, by providing the packing 7 which is a sealing member, the rotating shaft 42 can be disposed in a watertight manner with respect to the bearing portion 610 of the first case 61.

  As described above, in the liquid level detection device F in the present embodiment, the float 1 that floats on the liquid level, the float arm 2 that is displaced by the float 1, the circuit board 31 that includes the resistor, and the float arm 2 A liquid level detection device comprising a contact member 32 (sliding contact portion) that slides on the circuit board 31 with displacement and a case 6 that houses the circuit board 31 and the contact member 32 (sliding contact portion). F, a first holder 4 having holding portions 41a and 41b for holding the float arm 2 and a rotating shaft 42, a bearing portion 62 that rotatably supports the rotating shaft 42 and is provided in the case 6, and a contact member 32 (sliding contact portion) is held on the rotating shaft 42 and is rotated together with the rotating shaft 42, and welding is provided at the end of the rotating shaft 42 to join the second holder 5. Sudden 43 and a coupling hole 51 that is provided in the second holder 5 and is coupled to the welding projection 43 of the first holder 4, and the welding projection 43 provided in the first holder 4 is welded. Since the length of the rotating shaft 42 in the axial direction can be set short by welding and fixing the coupling hole 51 provided in the second holder 5, the liquid level detecting device F can be made thin. Thus, the first holder 4 that holds the float arm 2 and the second holder 5 that holds the contact member 32 (sliding contact portion) can be firmly fixed by welding.

  At this time, the end 2b of the float arm 2 is bent in a substantially L shape with respect to the main part 2a of the float arm 2, and the bent end 2b and the main part 2a adjacent to the end 2b are provided. The two places are provided so as to be held by holding parts (mounting parts) 41a and 41b provided in the first holder 4, but the surface of the first holder 4 provided with the holding parts 41a and 41b is By being provided on the outer peripheral wall side of the case 6 (first case 61), the float arm 2 can be easily assembled and fixed from the outside to the holding parts 41a and 41b. Can be performed satisfactorily.

  In addition, since the first holder 4 and the second holder 5 are formed of resin materials having different color tones, it is possible to easily determine whether or not the assembly position of each component according to the welded state is good.

  The first holder 4 is provided with a positioning portion 44 at the boundary between the rotating shaft 42 and the welding projection 43, and the second holder 5 is provided with an alignment portion 52 that engages with the positioning portion 44. As a result, the assembly position by welding and fixing the first holder 4 and the second holder 5 can be determined in a predetermined state by the positioning portion 44 and the alignment portion 52, and thereby the resistance provided on the circuit board 31. The body and the plurality of sliding electrodes can be assembled and held without any deviation of the set position with the contact member 32 (sliding contact portion) provided in the second holder 5 for stable liquid level detection. A signal can be sent out.

  Further, by molding the second case 62, which is at least a part of the case 6, with a see-through synthetic resin material, it is possible to determine the assembled state of the holders 4 and 5 from the outside. The state of welding or the like can be determined well. In this embodiment, the case 6 is formed so that at least a part thereof can be seen through, but in some cases, the cases 61 and 62 may be formed of an impermeable resin material.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in the above-described embodiment, the cylindrical shape provided in the first holder 4 is used. The positioning portion 44 for positioning and detent is provided at the root location (boundary location) of the rotating shaft 42, but the outer shape of the rotating shaft 42 is formed in a polygon such as a hexagonal column, for example. By forming the coupling hole 51 of the second holder 5 according to the shape, the first holder 4 and the second holder 5 can be coupled in a non-rotating state. Further, as a means for fixing the float arm 2, the shape and thickness of the first holder 4 are taken into consideration, and the shape of the float arm 2 and the shape of the holding portion of the first holder 4 are arbitrarily set to reduce the thickness (small size) Can be realized and the assembly workability can be improved.

F Liquid level detection device 1 Float 2 Float arm 3 Detection unit 4 First holder 5 Second holder 6 Case 7 Packing 31 Circuit board 32 Contact member 41a, 41b Holding unit 42 Rotating shaft 43 Welding projection 44 Positioning unit 51 For coupling Hole portion 52 Positioning portion 61 First case 62 Second case 610 Bearing portion 611 Connector portion 612 Terminal 613 Storage portion

Claims (4)

  A float that floats on a liquid surface, a float arm that is displaced by the float, a circuit board that includes a resistor, a contact member that slides on the circuit board as the float arm is displaced, the circuit board, and the circuit board In the liquid level detection device including a case for storing the contact member, a first holder including a holding portion for holding the float arm and a rotation shaft, and rotatably supporting the rotation shaft to the case. A bearing portion provided, a second holder that holds the contact member and is fixed to the rotation shaft and rotates together with the rotation shaft, and a weld provided to be coupled to the second holder at an end of the rotation shaft And a coupling hole provided in the second holder and coupled to the welding projection of the first holder, and provided in the first holder. Liquid level detecting apparatus characterized by being welded and fixed to said coupling hole provided in the second holder to wear projections by welding.   The liquid level detection device according to claim 1, wherein the first holder and the second holder are formed of resin materials having different color tones.   The first holder is provided with a positioning portion at a boundary between the rotating shaft and the welding projection, and the second holder is provided with a positioning portion that engages with the positioning portion. The liquid level detection device according to claim 1 or 2. The liquid level detection device according to claim 1, wherein at least a part of the case is formed of a transparent material.

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