JP2010230426A - Mounting structure of liquid level detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of a liquid level detector capable of suppressing the increase of costs and releasing the charge of a conductive arm to the outside. <P>SOLUTION: In a mounting structure of a liquid level detector 10 to a mounted member 20, the liquid detector 10 includes: a main part 15; a float floating on a liquid; a rotation part 13 rotatable with respect to the main part 15; and a conductive arm 12 which connects the float and the rotating unit 13 to convert the vertical motion of the float into the rotational motion of the rotating unit 13. The mounted member 20 includes a conductive part 25 which is conductive and is grounded, and has a structure in which an end part 121 of the arm 12 on the rotation part 13 side is grounded to the conductive part 25 with the liquid level detector 10 attached to the mounted member 20. With these structures, it is possible to suppress the increase of costs and release the charge of the conductive arm 12 to the outside. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mounting structure for a liquid level detection device for detecting a liquid level.

  Conventionally, in order to monitor the liquid level position of fuel stored in a fuel tank of an automobile, a liquid level detection device that electrically detects fluctuations in the liquid level has been used. The liquid level detection device is attached to a member to be attached such as a sub tank in the fuel tank.

  The liquid level detection device connects the main body, the float that floats on the liquid level, the rotating part that can rotate with respect to the main body part, and the float and the rotating part to convert the vertical movement of the float into the rotational movement of the rotating part. An arm for conversion; and a detecting means for detecting a rotation angle of the rotating portion with respect to the main body. The change in the liquid level is detected by detecting the change in the rotation angle of the rotating part with respect to the main body part.

  This liquid level detection device includes an electric resistance type liquid level detection device that detects a change in the rotation angle of the rotating part as a change in electric resistance, and a magnetoelectric conversion in which the change in the rotation angle of the rotating part is detected as a change in the magnetic flux density of the magnet. There is a magnetic liquid level detection device that detects an element.

  In any liquid level detection device, the fuel in the tank moves up and down and friction is generated between the float and the fuel, so static electricity is generated in the float. In general, since the arm is formed of a conductive material such as metal, the static charge moves from the float to the arm and accumulates on the arm. When the electric charge accumulated in the arm is discharged from the arm, the liquid level detection signal from the liquid level detection device is disturbed, so that the accuracy of the liquid level detection may be lowered.

  In order to suppress the discharge from the arm, in the electric resistance type liquid level detection device, the rotating part is formed of a conductive material, and the arm charge is always externally transmitted through the conductive rotating part, the sliding contact and the electric resistor. The structure which escapes is disclosed (patent document 1).

Japanese Patent No. 3941735

  However, the liquid level detection device described in Patent Document 1 has a problem that the manufacturing cost of the liquid level detection device increases because the entire rotating portion is made of conductive resin.

  In addition, since the fuel also moves up and down in the sub-tank, which is a member to be attached, and friction occurs between the sub-tank and the fuel, static electricity is also generated in the sub-tank. For this reason, a conductive part is provided in at least a part of the sub-tank, and the conductive part is grounded to release the charge of the sub-tank to the outside.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a mounting structure for a liquid level detection device capable of releasing the electric charge of a conductive arm to the outside while suppressing an increase in cost. And

  The present invention employs the following technical means to achieve the above object.

  According to invention of Claim 1, in the attachment structure of the liquid level detection apparatus with respect to a to-be-attached member, a liquid level detection apparatus is a rotation part which can rotate with respect to a main-body part, the float which floats on a liquid level, and a main-body part. And a conductive arm that connects the float and the rotating part to convert the vertical movement of the float into a rotating movement of the rotating part, and the mounted member includes a conductive conductive part that is grounded, In the state where the liquid level detection device is attached to the member to be attached, the arm has a structure in which the end portion on the rotating portion side contacts the conductive portion.

  According to this configuration, in a state where the liquid level detection device is attached to the attached member, the end portion on the rotating portion side of the conductive arm is brought into contact with the conductive portion grounded on the attached member. For this reason, the arm can be grounded through the conductive portion with a simple configuration in which the end portion of the arm is brought into contact with the conductive portion of the attached member. Therefore, the charge of the conductive arm can be released to the outside without increasing the cost.

  According to the invention of claim 2, the attached member includes an attached portion to which the main body portion is attached, and the end portion is arranged at the rotation center of the rotating portion.

  According to this configuration, the main body portion of the liquid level detection device is attached to the attached portion of the attached member, and the end portion on the rotating portion side of the arm is disposed at the rotation center of the rotating portion. For this reason, in a state where the liquid level detection device is attached to the attached member, regardless of the rotational position of the arm with respect to the main body, the relative arrangement of the end on the rotating portion side and the conductive portion of the attached member in the arm The relationship does not change. Therefore, the end of the arm can be brought into contact with the conductive portion of the attached member regardless of the rotation position of the arm with respect to the main body, without complicating the configuration. As a result, the charge of the conductive arm can be released to the outside while suppressing an increase in cost.

  According to the invention of claim 3, the end portion protrudes toward the attached member side from both the main body portion and the rotating portion, and the cantilever that bends in the abutting direction in which the end portion abuts the end portion at the conductive portion. It is characterized in that the part is a contact part.

  According to this configuration, since the cantilever that bends in the contact direction is a portion where the end of the arm contacts the conductive portion, the contact direction between the end of the arm and the portion where the end of the arm contacts Can be absorbed by the bending in the contact direction of the cantilever beam. In addition, since the cantilever can have a larger area than the end of the arm, the positional deviation in the surface direction perpendicular to the contact direction can be absorbed by the spread of the surface of the cantilever. Therefore, it is not necessary to form the end portion of the arm and the portion with which the end portion comes into contact with high accuracy, so that an attachment structure in which the end portion of the arm is brought into contact with the conductive portion can be realized while suppressing an increase in cost.

  According to invention of Claim 4, the to-be-attached member has a stopper for suppressing that the free end of a cantilever is excessively displaced to a contact direction.

  According to this configuration, since the stopper for suppressing the free end of the cantilever beam from being excessively displaced in the contact direction is provided, damage due to the excessive displacement of the cantilever beam can be suppressed. Therefore, it is possible to secure a mounting structure for bringing the end of the arm into contact with the conductive portion for a long time.

  According to the invention of claim 5, the cantilever has one or more curved portions that are curved along a direction connecting the support end and the free end in the cantilever.

  According to this configuration, not only the support end but also the bending portion becomes a bending node of the cantilever beam, and therefore stress concentration due to the bending of the cantilever beam occurs not only in the support end but also in the bending portion. For this reason, since this stress concentration is distributed to the support end and the curved portion, damage due to the stress concentration of the cantilever can be suppressed.

  Further, since the cantilever is gently bent at the bending portion, the stress concentration due to the bending of the cantilever is relaxed at the bending portion. For this reason, the damage by the stress concentration of a cantilever can be suppressed more. As a result, an attachment structure in which the end portion of the arm is brought into contact with the conductive portion can be secured for a longer period.

  According to the invention of claim 6, the end of the arm is formed in any one of a spherical shape, a curved surface shape and a pointed shape.

  According to this configuration, since the end portion of the arm has one of a spherical shape, a curved surface shape, and a sharp shape, the end portion of the arm and the conductive portion of the attached member are simply formed by the surface and the surface. The friction torque between the end portion of the arm and the conductive portion of the attached member can be reduced as compared with the case of surface contact. For this reason, damage due to friction of both the end of the arm and the conductive portion of the attached member can be suppressed, and a mounting structure in which the end of the arm is brought into contact with the conductive portion can be ensured for a longer period of time.

It is a front view which shows the attachment state of the fuel level gauge by one Embodiment of this invention. It is the II-II sectional view taken on the line in FIG. It is an enlarged view of the sub tank in the III section in FIG. It is an enlarged view of the IV section in FIG. It is an enlarged view of the edge part side of the arm of FIG. It is an enlarged view which shows the 1st modification of FIG. It is an enlarged view which shows the 2nd modification of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the mutually same or equivalent part in a figure.

(Constitution)
FIG. 1 is a front view showing an attached state of a fuel level gauge according to an embodiment of the present invention. The fuel level gauge 10 shown in FIG. 1 is attached to the sub tank 20 in the fuel tank 30 and detects the liquid level positions L1 and L2 of the fuel LQ stored in the fuel tank 30.

  The fuel level gauge 10 connects the main body 15, the float 11 floating on the liquid level of the fuel LQ, the rotating part 13 that can rotate with respect to the main body 15, and the float 11 and the rotating part 13. And an arm 12 that converts the vertical movement of the rotation into the rotational movement of the rotating unit 13. The float 11 is made of an insulating resin or the like, and has an apparent specific gravity so as to surely float on the liquid surface of the fuel LQ. The rotating portion 13 and the main body portion 15 are also formed from an insulating resin or the like, and the arm 12 is formed from a conductive material such as a metal rod. When the float 11 moves up and down as the fuel level of the fuel LQ fluctuates, this movement is transmitted to the rotating unit 13 by the arm 12 and converted into a rotating motion of the rotating unit 4 with respect to the main body unit 15.

  The liquid level position L1 of the fuel LQ indicates a substantially empty state in the fuel tank 30, and the liquid level position L2 of the fuel LQ indicates a full tank state. FIG. 1 shows the fuel level gauge 10 in the case of the liquid level position L1, and the float 11 in the case of the liquid level position L2 and the liquid level position L2 is indicated by a two-dot chain line. When the fuel LQ changes between the nearly empty liquid level position L1 and the fully filled liquid level position L2, the float 11 moves up and down in conjunction with the change, and the rotating part 13 moves with respect to the main body part 15 in a predetermined manner. It is comprised so that it may rotate within the rotation range.

  As shown in FIGS. 1 and 2, a ceramic substrate 16 on which an electric resistor 17 is formed is fixed to the main body portion 15, and an electric resistance is connected to the rotating portion 13 while being electrically connected to the electric resistor 17. A sliding contact 14 that slides on the body 17 is fixed. For this reason, when the rotating part 13 rotates with respect to the main body part 15, the sliding contact 14 slides on the electric resistor 17 with this rotation. The electric resistor 17 and the sliding contact 14 are configured such that the electric resistance changes depending on the sliding position of the sliding contact 14 with respect to the electric resistor 17, and the fuel LQ is measured by measuring the change in the electric resistance. It is comprised so that the liquid level position of can be detected.

  As shown in FIGS. 1 and 3, attached portions 21 and 22 to which the main body portion 15 of the fuel level gauge 10 is attached are formed in the sub tank 20. The attached portion 21 is inserted into the opening 151 formed in the main body portion 15, and the main body portion 15 (that is, the fuel level gauge 10) is attached to the sub tank 20. The attached portion 22 is in contact with the tip of the arm portion 152 formed on the main body portion 15 so that the main body portion 15 does not come off the sub tank 20 in the upward direction of FIGS. It is.

  The basic configuration of the fuel level gauge 10 mounting structure with respect to the sub tank 20 has been described above. Hereinafter, a characteristic configuration of the mounting structure will be described with reference to FIGS.

(Characteristic configuration)
As shown in FIG. 2, the end portion 121 on the rotating portion 13 side of the arm 12 is disposed at the rotation center (rotation center axis) RC of the rotating portion 13, and the end portion 121 is positioned on both the main body portion 15 and the rotating portion 13. Rather than the sub tank 20 side (right side in FIGS. 2 and 4). The end 121 is formed in a sharp shape as shown in FIGS.

  The sub tank 20 is formed of a conductive resin or the like and is grounded. As shown in FIGS. 2 and 4, the sub tank 20 is a conductive material that bends in the abutting direction DF where the end 121 abuts against the concave portion 23 of the sub tank 20. The cantilever 25 is provided. One end of the cantilever 25 is supported by the support end 251 by the main body portion of the sub tank 20, and the other end is a free end 252. The cantilever 25 is formed integrally with the sub tank 20 from a conductive resin or the like. Therefore, the conductive cantilever 25 is grounded through the grounded conductive sub tank 20.

  The cantilever 25 is a portion where the end 121 of the arm 12 abuts in the conductive sub-tank 20, and the cantilever 25 is positioned more than the end 121 of the arm 12 as shown in FIGS. 2 and 3. A large area. As shown in FIG. 4, the cantilever 25 is provided with four curved portions 253 that are curved along the direction connecting the support end 251 and the free end 252, and the cantilever 25 has the curved portion 253. In FIG. 4, the structure is curved alternately left and right (in a gentle zigzag shape). In addition to the support end 251, the curved portion 253 is also a bending node of the cantilever beam 25. However, since the cantilever beam 25 is gently bent at the curved portion 253, the cantilever beam 25 is bent. The stress concentration is caused by relaxation in the curved portion 253. Note that the number of the bending portions 253 is not limited to four, and may be one or more.

  In FIG. 4, the bottom surface 24 of the recess 23 is formed in each shape of the recess 23 and the cantilever 25 so as to serve as a stopper for suppressing the free end 252 of the cantilever 25 from being excessively displaced in the contact direction DF. The relative arrangement of the bottom surface 24 of the recess 23 and the free end 252 of the cantilever 25 is set.

  With the fuel level gauge 10 configured as described above attached to the sub tank 20, as shown in FIGS. 2 and 4, the end 121 is brought into contact with the cantilever 25.

  The fuel level gauge 10 corresponds to the liquid level detection device described in the claims, the sub tank 20 corresponds to the mounted member and the conductive portion described in the claims, and the bottom surface 24 corresponds to the stopper described in the claims. To do.

(Function and effect)
Next, the operation and effect of the structure for attaching the fuel level gauge 10 to the sub tank 20 according to the present embodiment will be described with reference to FIGS.

  In the mounting structure according to the present embodiment, as a characteristic configuration, as shown in FIGS. 2 and 4, the end 121 on the rotating unit 13 side of the conductive arm 12 in a state where the fuel level gauge 10 is mounted on the sub tank 20. Is brought into contact with a conductive cantilever 25 grounded in the sub tank 20. Therefore, the arm 12 can be grounded through the cantilever 25 with a simple configuration in which the end 121 of the arm 12 is brought into contact with the cantilever 25 in the sub tank 20. Therefore, the charge of the conductive arm 12 can be released to the outside without increasing the cost.

  Further, as shown in FIG. 3, the main body portion 15 of the fuel level gauge 10 is attached to the attached portions 21 and 22 of the sub tank 20, and the end 121 on the rotating portion 13 side of the arm 12 is shown in FIGS. 2 and 4. As shown in FIG. 4, the rotation part 13 is disposed at the rotation center RC. For this reason, in a state where the fuel level gauge 10 is attached to the sub tank 20, regardless of the rotation position of the arm 12 with respect to the main body portion 15, the end portion 121 on the rotating portion 13 side in the arm 12 and the cantilever 25 of the sub tank 20 The relative arrangement relationship of is not changed. Therefore, the end 121 of the arm 12 can be brought into contact with the cantilever 25 of the sub tank 20 regardless of the rotation position of the arm 12 with respect to the main body 15 without complicating the configuration. As a result, the cost of the conductive arm 12 can be released to the outside while suppressing an increase in cost.

  Further, since the cantilever 25 bent in the abutting direction DF shown in FIGS. 2 and 4 is a portion where the end 121 of the arm 12 abuts in the conductive sub tank 20, the end 121 of the arm 12 and the arm The positional deviation in the abutting direction DF with the portion (cantilever 25) with which the twelve end portions 121 abut can be absorbed by the deflection in the abutting direction DF of the cantilever 25. 2 and 3, since the cantilever 25 has a larger area than the end 121 of the arm 12, the surface direction perpendicular to the contact direction DF (the surface direction of the cantilever 25). Can be absorbed by the spread of the surface of the cantilever 25. Therefore, since it is not necessary to form the end 121 of the arm 12 and the cantilever 25 with high precision, the mounting structure in which the end 121 of the arm 12 is brought into contact with the conductive cantilever 25 increases the cost. It can be realized with restraint.

  Further, in FIG. 4, since the bottom surface 24 of the recess 23 is provided as a stopper for preventing the free end 252 of the cantilever 25 from being excessively displaced in the contact direction DF, the excessive displacement of the cantilever 25 Damage due to can be suppressed. Therefore, it is possible to secure a mounting structure for bringing the end 121 of the arm 12 into contact with the cantilever 25 for a long period of time.

  Further, in FIG. 4, not only the support end 251 but also the curved portion 253 also becomes a bending node of the cantilever 25, and therefore stress concentration due to the bending of the cantilever 25 is not limited to the support end 251. This also occurs in the curved portion 253. For this reason, since this stress concentration is distributed to the support end 251 and the curved portion 253, damage due to the stress concentration of the cantilever 25 can be suppressed. In addition, since the cantilever 25 is gently curved at the bending portion 253, stress concentration due to the bending of the cantilever 25 is relaxed at the bending portion 253. For this reason, the damage by the stress concentration of the cantilever 25 can be suppressed more. As a result, an attachment structure in which the end 121 of the arm 12 is brought into contact with the cantilever 25 can be secured for a longer period.

  Furthermore, as shown in FIG. 5, since the end 121 of the arm 12 has a sharp shape, it is compared with a case where the end 121 of the arm 12 and the cantilever 25 are simply brought into surface contact with each other. Thus, the friction torque between the end 121 of the arm 12 and the cantilever 25 can be reduced. For this reason, damage due to friction of both the end 121 of the arm 12 and the cantilever 25 can be suppressed, and a mounting structure for bringing the end 121 of the arm 12 into contact with the cantilever 25 is ensured for a longer period of time. it can.

(Modification)
In the above example, the end 121 of the arm 12 has a pointed shape. However, as shown in FIG. 6, the end 122 of the arm 120 can also have a spherical shape, as shown in FIG. The end portion 124 of the arm 123 can also have a curved shape. Even in these cases, the end portions 122 and 124 of the arms 120 and 123 and the end portions 122 and 124 of the arms 120 and 123 are compared with the case where the end portions 122 and 124 of the arms 120 and 123 are simply brought into surface contact with each other. The friction torque with the cantilever 25 can be reduced. Therefore, it is possible to suppress damage due to friction of both the end portions 122 and 124 of the arms 120 and 123 and the cantilever beam 25, and the end portions 122 and 124 of the arms 120 and 123 are brought into contact with the cantilever beam 25. The mounting structure can be secured for a longer period.

  In the above example, the entire sub-tank 20 including the cantilever beam 25 is made conductive, and these are grounded. However, if the cantilever 25 is grounded as a conductive material, the grounded conductive material is used. It is also possible to have a structure in which the conductive portion is partially provided in the sub tank 20. Even in such a mounting structure, the same effect as described above can be obtained.

  In the above example, the end 121 of the arm 12 is brought into contact with the cantilever 25. However, if the conductive portion is grounded in the sub tank 20, the end 121 of the arm 12 is brought into contact with the conductive portion. An attachment structure can also be used.

  In the above-described example, the end 121 of the arm 12 is arranged at the rotation center (rotation center axis) RC of the rotation unit 13, but it can also be arranged at a position removed from the rotation center RC. In this case, the relative positional relationship between the end 121 of the arm 12 and the sub tank 20 varies depending on the rotational position of the arm 12 with respect to the main body 15. Therefore, a conductive structure that is grounded is provided in the sub-tank 20 within a range that can cover this, and the end portion 121 of the arm 12 is brought into contact with the conductive part.

  It should be noted that not only the combination of the parts that clearly indicate that the combination is possible in the above-described embodiment or modification, but also the above-described implementation even if it is not clearly indicated if there is no problem with the combination. It is also possible to partially combine forms and modifications.

DESCRIPTION OF SYMBOLS 10 Fuel level gauge (liquid level detection apparatus), 11 Float, 12 Arm 121 End part, 13 Rotating part, 14 Sliding contact, 15 Main body part, 151 Opening 152 Arm part, 16 Ceramic substrate, 17 Electrical resistor 20 Sub tank ( (Attached member, conductive part), 21, 22 attached part, 23 recess 24 bottom surface (stopper), 25 cantilever (conductive part), 251 support end 252 free end, 253 curved part, LQ fuel, L1, L2 liquid Surface position RC Center of rotation

Claims (6)

In the mounting structure of the liquid level detection device to the mounted member,
The liquid level detecting device connects the main body, a float floating on the liquid level, a rotating part rotatable with respect to the main body, and the float and the rotating part to move the float up and down. A conductive arm that converts the rotational movement of the rotating part,
The attached member includes a conductive part that is grounded,
An attachment structure for a liquid level detection device, wherein the arm has a structure in which an end on the rotating portion side contacts the conductive portion in a state where the liquid level detection device is attached to the attachment member. The attached member includes a attached portion to which the main body portion is attached;
The mounting structure for a liquid level detection device according to claim 1, wherein the end portion is disposed at a rotation center of the rotating portion. The end portion protrudes toward the attached member side from both the main body portion and the rotating portion,
The mounting structure for a liquid level detection device according to claim 1, wherein the cantilever that bends in a contact direction in which the end abuts is a portion in which the end abuts in the conductive portion. .   4. The liquid level detection device according to claim 3, wherein the attached member has a stopper for preventing the free end of the cantilever from being excessively displaced in the contact direction. 5. Mounting structure.   5. The liquid surface according to claim 3, wherein the cantilever has one or more curved portions that are curved in a direction connecting the support end and the free end in the cantilever. Detection device mounting structure.   6. The liquid level detection device according to claim 1, wherein the end portion of the arm is formed in any one of a spherical shape, a curved surface shape, and a pointed shape. Mounting structure.

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