JP2010038550A - Liquid level detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid level detection device for simplifying a manufacturing process by simplifying a structure of a contact member, and suppressing manufacturing cost. <P>SOLUTION: This liquid level detection device 1 includes a float arm 2 moving following fluctuation of a liquid level, an arm holder 3 for holding the float arm 2 and a circuit board 5, contact members 8, 9 to be in sliding contact respectively with a plurality of electrodes 13 and a fixed electrode 14 provided on the circuit board 5, and a frame 4 for holding the contact members 8, 9 and supporting the float arm 2 rotatably. In the device 1 for outputting an electric signal whose resistance value is changed by bringing the contact member 8 into contact with at least one of the plurality of electrodes 13 following fluctuation of the float arm 2, the contact members 8, 9 are equipped in a body with contacts 6, 7 to be slid along the circuit board 5 and terminal parts 10, 11 for transferring electric signals from the contacts 6, 7 to the outside, and the terminal parts 10, 11 are equipped with hollow parts 10a, 10b formed by bending. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid level detection device, and in particular, includes a contact member formed integrally with a contact for sliding an electrode on a circuit board and a terminal portion for transmitting an electric signal from the contact to the outside. The present invention relates to a liquid level detection device.

  A conventional liquid level detection apparatus includes a float arm having a float that moves with a change in liquid level, a hard circuit board, a resistor provided on the circuit board, and the resistor provided on the circuit board. A plurality of electrodes to be connected to each other, an arm holder for holding the float arm and the circuit board, a contact member for sliding contact with the plurality of electrodes, and holding the contact member and allowing the float arm to rotate And a frame for supporting, and outputs an electrical signal in which the resistance value of the resistor is changed by the contact member contacting at least one of the plurality of electrodes in accordance with the variation of the float arm.

The contact member of the liquid level detection device is provided by insert formation in a connector portion formed in the frame. The configuration of the contact member is a configuration including a contact made of an elastic material having a thickness of 0.15 mm that is in contact with the plurality of electrodes, and a terminal portion having a thickness (for example, 0.5 mm) thicker than the contact, The contact point is fixed to the terminal part by crimping or welding to adopt a structure that improves electrical connection reliability.
JP-A-2005-241553

  However, in this liquid level detection device, since the contact member is composed of two members and a structure in which both members are joined using a technique such as crimping or welding, the number of parts is large. In addition to complicating the manufacturing process of the liquid level detection device, there is a problem that the manufacturing cost is increased.

  Therefore, the present invention pays attention to the above-mentioned problems, and provides a liquid level detection device that simplifies the manufacturing process by simplifying the structure of the contact member and can reduce the manufacturing cost.

  In order to achieve the above-mentioned object, the present invention provides a float arm having a float that moves in accordance with a change in liquid level, a rigid circuit board, a resistor provided on the circuit board, and the circuit board provided on the circuit board. A plurality of electrodes connected to the resistor, a fixed electrode different from the plurality of electrodes, an arm holder for holding the float arm and the circuit board, and a sliding contact with each of the plurality of electrodes and the fixed electrode A contact member that holds the contact member and rotatably supports the float arm, and the contact member contacts at least one of the plurality of electrodes as the float arm varies. In the liquid level detection device that outputs an electrical signal in which the resistance value of the resistor is changed, the contact member includes a contact that slides on the circuit board and the contact. And a terminal portion of the for transmitting the electrical signal to the outside together, the terminal portions are those having a hollow portion formed by bending.

  In addition, a part of the hollow portion is embedded in the frame.

  Further, two hollow portions are provided in the terminal portion.

  As described above, according to the present invention, there is provided a liquid level detection device that can achieve the intended purpose, simplify the manufacturing process by simplifying the structure of the contact member, and reduce the manufacturing cost. Can be provided.

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

  The liquid level detection device 1 of the present embodiment includes a float arm 2 provided with an unillustrated float that floats on the liquid level and moves with the fluctuation, an arm holder 3 that holds the float arm 2, and an arm holder. 3 and a frame 4 that rotatably supports the float arm 2. The arm holder 3 is provided with a circuit board 5, and the frame 4 is provided with contact members 8 and 9 having first and second contacts 6 and 7. The contact members 8 and 9 are integrally formed with terminal portions 10 and 11.

  The float arm 2 is a metal wire having rigidity and includes the float at one end and an end 2a formed by bending at the other end. This end 2a is the center at which the float arm 2 rotates.

  The arm holder 3 is made of a synthetic resin and has a disk shape in the present embodiment. The float arm 2 and the circuit board 5 are held. The arm holder 3 includes a hole 3a through which the end 2a of the float arm 2 passes. Further, a cylindrical shaft portion 3b is provided on the back surface of the arm holder 3 so as to correspond to the hole 3a. Two elastically deformable locking pieces 3d having locking claws 3c are provided at the tip of the shaft portion 3b. The locking piece 3d provided with the locking claw 3c is for rotatably mounting the arm holder 3 to the frame 4.

  Two arm holding portions 3e having an inverted L shape are formed on the upper surface of the arm holder 3. The arm holding portion 3e is fixed with the float arm 2 interposed therebetween. The arm holding portion 3e is elastically deformable and has an opening 3f smaller than the diameter of the float arm 2. The float arm 2 is sandwiched and fixed from the opening 3f. Although two arm holding portions 3e are formed, either one may be used to fix the float arm 2, and which arm holding portion 3e is used depends on the liquid level detection of the present invention. What is necessary is just to select suitably according to the use conditions of the apparatus 1. FIG.

  Further, a wall 3g extending to the frame 4 side is formed on the outer periphery of the arm holder 3. A protrusion 3h protruding outward is formed on a part of the wall 3g. The protrusion 3 h is a rotation restricting portion that abuts the frame 4 and restricts the rotation range of the arm holder 3.

  A positioning wall portion 3 i for determining the fixing position of the circuit board 5 is formed on the back surface of the arm holder 3. The positioning wall portion 3 i is provided so as to surround the circuit board 5. In addition, a wall 3j for raising the bottom is formed in the positioning wall 3i so that the surface of the circuit board 5 has substantially the same height as the back surface of the arm holder 3. In addition, the arm holder 3 is provided with two elastic pieces 3m provided with claws 3k in order to fix the circuit board 5, and the elastic pieces 3m provided with the two claws 3k make the circuit board 5 elastic. It is pressed against the positioning wall 3i on the side where the piece 3m is not provided.

  The frame 4 is made of a synthetic resin, and is formed of the same material as that of the arm holder 3 in this embodiment. The frame 4 is fixed to an attachment member such as a stay provided for fixing the liquid level detection device 1 in the fuel tank. The frame 4 is provided with a cylindrical projecting portion 4a having a bearing portion 4b formed of a through hole at the center for mounting the arm holder 3 rotatably. The opening of the bearing portion 4b on the back surface of the frame 4 serves as an engaging portion 4c to which the locking claw 3c of the arm holder 3 is locked.

  In addition, the frame 4 has a quadrangular shape in the present embodiment, and includes protrusions 4d at the four corners. Two of the protrusions 4d are rotation restricting portions with which the protrusions 3h of the arm holder 3 abut, and restrict the rotation of the arm holder 3. A wall 4e is provided around the frame 4 so as to connect the protrusions 4d. The wall 4e and the wall 3g of the arm holder 3 can be brought into contact with each other, and excessive blurring is suppressed when the arm holder 3 rotates. The frame 4 includes a connector portion 4f, and contact members 8 and 9 are embedded and fixed to the connector portion 4f by insert molding.

  The circuit board 5 is a hard circuit board, and ceramic is used in this embodiment. A through hole 5 a is formed at the center of the circuit board 5. The through hole 5a is formed through the shaft portion 3b of the arm holder 3 and the protruding portion 4a of the frame 4. The circuit board 5 is housed in a positioning wall 3i formed on the arm holder 3, and is fixed to the arm holder 3 by claws 3k provided on the elastic piece 3m.

  Two resistors 12 a and 12 b are provided on the circuit board 5. The resistors 12a and 12b are made of ruthenium oxide or the like. A plurality of electrodes 13 connected to the resistors 12a and 12b are provided. The material of the electrode 13 is made of silver palladium alloy or the like. The electrodes 13 are independent of each other and are connected by resistors 12a and 12b. The electrode 13 forms a first sliding path through which the second contact 7 of the contact member 9 slides.

  On the circuit board 5, a fixed electrode 14 that is different from the plurality of electrodes 13 and is electrically connected via a resistor 15 is formed. The fixed electrode 14 is also made of the same material as the electrode 13. The fixed electrode 14 forms a second sliding path through which the first contact 6 of the contact member 8 slides. The resistor 15 is also made of the same material as the resistors 12a and 12b. The shape of the electrodes 13 and 14 with which the first and second contacts 6 and 7 come into contact is a point-symmetric shape with respect to the rotation center where the circuit board 5 rotates together with the arm holder 3. Since it is rectangular, even if the circuit board 5 is inverted 180 degrees and attached, there is no problem in detecting the liquid level, so that there is no problem of incorrect circuit board assembly.

  Further, the surface of the circuit board 5 on which the electrodes 13 and 14 are provided is opposed to the frame 4, and as a result, is covered with the frame 4, and the side on which the electrodes 13 and 14 are provided is exposed to the outside. Therefore, contact with other parts is prevented, and disconnection of the electrodes 13 and 14 can be prevented.

  The first and second contacts 6 and 7 are formed on the contact members 8 and 9, respectively. The contact members 8 and 9 are plate-shaped, and the material thereof is white in this embodiment. The first and second contacts 6 and 7 have a plurality of contact points, and in the present embodiment, three are provided. Further, in order for the first and second contacts 6 and 7 to contact the electrodes 13 and 14 satisfactorily, they are bent upward in the middle of the contact members 8 and 9 in FIG. Moreover, the front-end | tip part is bend | folded below in FIG. 4 so that the 1st, 2nd contacts 6 and 7 can slide the electrodes 13 and 14 favorably. The arm holder 3 is pushed in a direction away from the frame 4 with respect to the rotation axis direction by the elastic force of the contact members 8 and 9.

  The contact members 8 and 9 are integrally formed with the terminal portions 10 and 11 as described above. The terminal portions 10 and 11 are male and are connected to a female terminal (not shown) that is electrically connected to an external circuit.

  The thickness of the contact members 8 and 9 is 0.15 mm. This is because the first and second contacts 6 and 7 are in good contact with the electrode 13. Moreover, since the thickness of the terminal portions 10 and 11 is required to be about 0.5 mm in order to make good contact with the female terminal, the terminal portions 10 and 11 bend the contact members 8 and 9. In addition, hollow portions 10a and 11a are formed. The hollow portions 10a and 11a are formed by bending the end portions of the contact members 8 and 9 forming the terminal portions 10 and 11 along the center line of the contact members 8 and 9 in the longitudinal direction. , 11, two are provided. Thus, by bending the terminal portions 10 and 11 to form the hollow portions 10a and 11a, the reliability of electrical connection with the female terminal can be improved.

  Further, a part of the hollow portions 10 a and 11 a is embedded in the frame 4. The first and second contact points 6 and 7 side of the hollow portions 10a and 11a have water tightness, and when the contact members 8 and 9 are insert-molded, the resin is contained in the hollow portions 10a and 11a. Prevent entry.

  In addition, by embedding a part of the hollow portions 10a and 11a in the frame 4, the strength of the terminal portions 10 and 11 can be ensured, and damage such as bending at the time of contact with the female terminal can be prevented. Can do.

  In the liquid level detection device 1, the float arm 2 and the arm holder 3 rotate with the fluctuation of the float. As a result, the circuit board 5 fixed to the arm holder 3 rotates. With this rotation, the first contact 6 comes into contact with at least one of the electrodes 13. As a result, an electrical signal in which the resistance values of the resistors 12a and 12b are changed is output to the external circuit.

  The liquid level detection device 1 configured as described above provides a liquid level detection device that simplifies the manufacturing process by simplifying the structure of the contact members 8 and 9, and can reduce the manufacturing cost. Can do.

The front view of 1st Embodiment of this invention. The side view of the embodiment. Sectional drawing of the AA line in FIG. Sectional drawing of the BB line in FIG. Sectional drawing of CC line in FIG. Sectional drawing of the DD line | wire in FIG. The front view of the flame | frame of the embodiment. The rear view of the arm holder of the embodiment. The front view of the contact member of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid level detection apparatus 2 Float arm 3 Arm holder 4 Frame 4a Protrusion part 5 Circuit board 6 1st contact 7 2nd contact 8, 9 Contact member 10,11 Terminal part 10a, 11a Hollow part 12a, 12b Resistor 13 electrode

Claims (3)

A float arm having a float that moves in accordance with a change in liquid level, a hard circuit board, a resistor provided on the circuit board, and a plurality of electrodes provided on the circuit board and connected to the resistor; A fixed electrode different from the plurality of electrodes, an arm holder for holding the float arm and the circuit board, a contact member in sliding contact with the plurality of electrodes and the fixed electrode, and holding the contact member And a frame that rotatably supports the float arm, and the contact member is in contact with at least one of the plurality of electrodes as the float arm fluctuates to change the resistance value of the resistor. In the liquid level detection device that outputs a signal, the contact member transmits a contact that slides on the circuit board and the electrical signal from the contact to the outside. Integrally provided with terminal portions of the eye, said terminal portion, a liquid level detecting apparatus characterized by comprising a hollow portion formed by bending. The liquid level detection device according to claim 1, wherein a part of the hollow portion is embedded in the frame. The liquid level detection device according to claim 2, wherein two hollow portions are provided in the terminal portion.

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