Liquid level detection device

Abstract

To provide a liquid level detection device which can easily mount an arm on a holder.SOLUTION: A liquid level detection device includes a float, a rotation part 20 having a holder 22 for holding a magnet, and an arm 11 for connecting the float and the rotation part 20. The arm 11 has a straight part 11c which linearly extends, and an end 11a to be inserted which is an end in a part bent from the straight part 11c and is inserted into the holder 22. The holder 22 has a first arm insertion hole 24a into which the end 11a to be inserted can be inserted, a first arm presser 25a for pressing the straight part 11c, and an arm hook 26 hooked on the straight part 11c. The straight part 11c is sandwiched between the first arm presser 25a and the arm hook 26. The arm hook 26 is positioned between the first arm insertion hole 24a and the first arm presser 25a.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a liquid level detection device.

Background Art

[0002] For example, the liquid level detection device described in Patent Document 1 includes a float that floats on a liquid, a holder rotatably provided with respect to a main body frame, and an arm that rotates the holder according to the displacement of the float. In this liquid level detection device, a shaft hole through which an end portion of the arm penetrates is provided in the arm holder, and a bearing portion that receives the end portion of the arm penetrating through the shaft hole is provided in the main body frame. A push nut is press-fitted into the end portion of the arm that further penetrates through this bearing portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the structure described in Patent Document 1, since a push nut is used as a mechanism for preventing the arm from coming off the holder, there is a risk that the arm attachment process becomes complicated.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a liquid level detection device capable of easily attaching an arm to a holder.

Means for Solving the Problems

[0006] To achieve the above object, the liquid level detection device according to the present disclosure is a float that floats on a liquid and is displaced according to the position of the liquid level of the liquid, a rotating part having a magnet and a holder that holds the magnet, and being rotatable about an axis, A magnetic detection element that detects a change in a magnetic field accompanying rotation of the rotating part; An arm that connects the float and the rotating part and rotates the rotating part in response to displacement of the float; The arm has a straight part that extends linearly and an inserted end that is the end of a bent part from the straight part and is inserted into the holder. The holder has An arm insertion hole into which the inserted end can be inserted; An arm presser that presses the straight part; An arm hook that is hung on the straight part; The straight part is sandwiched between the arm presser and the arm hook; The arm hook is located between the arm insertion hole and the arm presser.

Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a liquid level detection device in which an arm can be easily attached to a holder.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Best Mode for Carrying Out the Invention

[0009] An embodiment of the present disclosure will be described with reference to the drawings.

[0010] The liquid level detection device 1 shown in FIG. 1 detects the position (liquid level) of the liquid surface of the liquid contained in a tank (not shown). For example, the liquid level detection device 1 is attached to the fuel tank of a vehicle and detects the liquid level according to the amount of gasoline as the liquid.

[0011] Hereinafter, when explaining each part included in the liquid level detection device 1, the X, Y, and Z axes orthogonal to each other may be appropriately used. The Y axis extends in the vertical direction of FIG. 1. The Z axis is parallel to the axis AX described later. Also, the direction in which the arrow indicating each axis of the X, Y, and Z axes points is the + (plus) direction of each axis, and the opposite direction is the - (minus) direction.

[0012] As shown in FIGS. 1 to 8 as appropriate, the liquid level detection device 1 includes a float 10, an arm 11, a rotating part 20, a magnetic detection element 30, a case 40 (an example of a support member) that rotatably supports the rotating part 20, a non-magnetic member 50, a PCB (Printed Circuit Board) 60, a wiring part 70, and a grommet 80.

[0013] The float 10 floats on the liquid whose liquid level is to be detected and is displaced together with the liquid surface. The float 10 is formed of, for example, synthetic rubber or the like.

[0014] The arm 11 connects the float 10 and the holder 22 of the rotating part 20, and rotates the rotating part 20 according to the displacement of the float 10. The arm 11 is formed of, for example, a metal that is a non-magnetic body.

[0015] The arm 11 has an inserted end portion 11a inserted into the holder 22, a holding end portion 11b holding the float 10, and a straight portion 11c located between the inserted end portion 11a and the holding end portion 11b. The straight portion 11c is a portion extending linearly. The inserted end portion 11a is located closer to the rotating portion 20 than the straight portion 11c and is the end of a portion bent approximately L-shaped from the straight portion 11c. The holding end portion 11b is located closer to the float 10 than the straight portion 11c and is the end of a portion bent approximately L-shaped from the straight portion 11c.

[0016] The rotating portion 20 is configured to be rotatable about the axis AX with respect to the case 40. The rotating portion 20 has two magnets 21a, 21b and a holder 22 that holds these magnets 21a, 21b. The rotating portion 20 generates a magnetic field that can be detected by the magnetic detection element 30 by the magnets 21a, 21b. This magnetic field changes as the rotating portion 20 rotates.

[0017] The magnets 21a, 21b are made of known materials such as neodymium and ferrite and are respectively disposed in the recesses G1, G2 described later. The magnet 21a and the magnet 21b are magnetized, for example, with two poles in the radial direction centered on the axis AX so as to generate a magnetic field between the two. The magnets 21a, 21b are each formed along an arc centered on the axis AX and face each other in the radial direction centered on the axis AX.

[0018] The holder 22 is generally annularly configured and includes an annular portion 220 provided with a through hole R at its center and an arm support portion 23 integrally formed with the annular portion 220 and supporting the arm 11. The holder 22 is, for example, an injection molded product formed of a synthetic resin material. The shaft portion 42, which will be described later, of the case 40 is inserted into the through hole R.

[0019] As shown in FIG. 4, the annular portion 220 includes recessed portions G1 and G2 that accommodate the magnets 21a and 21b, and locking portions 22e and 22f that lock the magnets 21a and 21b. FIG. 4 is a perspective view of the holder 22 as viewed from the back side (the side of the case 40), and for the sake of explanation, shows a state in which the magnet 21a among the magnets 21a and 21b is accommodated in the recessed portion G1.

[0020] The recessed portions G1 and G2 are provided to accommodate the magnets 21a and 21b, and are portions that are respectively recessed in the +Z direction from the side of the case 40 in the annular portion 220. The magnet 21a is accommodated (press-fitted) in the recessed portion G1. The magnet 21b is accommodated (press-fitted) in the recessed portion G2.

[0021] On the inner circumference of the recessed portion G1, a crush rib Q1 is formed along the axis AX and abuts against the outer circumference of the magnet 21a. In the present embodiment, five crush ribs Q1 are provided. Here, the inner circumference of the recessed portion G1 is a surface along an arc centered on the axis AX, and includes two curved surfaces sandwiching the locking portion 22e described later, one curved surface closer to the axis AX than these two curved surfaces, and two planes along the radial direction of the axis AX. In this way, a crush rib Q1 protruding toward the magnet 21a is provided at an intermediate position of each of the five surfaces included in the inner circumference of the recessed portion G1. The magnet 21a is press-fitted and fixed into the recessed portion G1 in such a manner that it is pushed by each of the five crush ribs Q1 provided across the outer circumference of the magnet 21a. Thereby, when the magnet 21a is inserted into the recessed portion G1, it is possible to suppress the holder 22 from cracking.

[0022] Similarly, on the inner circumference of the recessed portion G2, a crush rib Q2 is formed which is provided along the axis AX and abuts against the outer circumference of a magnet 21b (not shown in FIG. 4 as described above). In the present embodiment, five crush ribs Q2 are provided. Here, the inner circumference of the recessed portion G2 is a surface along an arc centered on the axis AX, and includes two curved surfaces sandwiching a locking portion 22f described later, one curved surface closer to the axis AX than these two curved surfaces, and two planes along the radial direction of the axis AX. Thus, a crush rib Q2 protruding toward the magnet 21b is provided at an intermediate position of each of the five surfaces included in the inner circumference of the recessed portion G2. The magnet 21b is press-fitted and fixed into the recessed portion G2 in such a manner that it is pushed by each of the five crush ribs Q2 provided across the outer circumference of the magnet 21b. Thereby, when the magnet 21b is inserted into the recessed portion G1, it is possible to suppress the occurrence of cracks in the holder 22.

[0023] The recessed portion G2 has a bottom portion G2a corresponding to its bottom. Similarly, the recessed portion G1 has a bottom portion G1a corresponding to its bottom (in FIG. 4, since the bottom portion G1a is not visible due to the magnet 21a, the corresponding position is indicated by a dashed line). A groove U2 is formed in a part of the bottom portion G2a corresponding to the crush rib Q2. The groove U2 is formed in a concave shape around the end portion on the bottom portion G2a side of the crush rib Q2. Although not all shown, five grooves U2 are provided corresponding to each of the five crush ribs Q2.

[0024] The groove U2 can store the shaving powder generated by shaving the crush rib Q2 when the magnet 21b is inserted into the recessed portion G2. Thereby, it is possible to prevent the shaving powder from accumulating over the entire bottom portion G2a and prevent a decrease in the holding force of the magnet 21b by the recessed portion G2.

[0025] Similarly, a groove (not shown) is formed in a part of the bottom G1a corresponding to the crash rib Q1. Five such grooves are provided corresponding to each of the five crash ribs Q1. This groove can prevent chips from accumulating across the entire bottom G1a and prevent a decrease in the holding force of the magnet 21a due to the recessed portion G1.

[0026] The locking portion 22e is a hook-shaped portion provided at a part of the outer periphery of the recessed portion G1, and locks while covering the outer edge portion of the magnet 21a accommodated in the recessed portion G1. Similarly, the locking portion 22f is a hook-shaped portion provided at a part of the outer periphery of the recessed portion G2, and locks while covering the outer edge portion of the magnet 21b accommodated in the recessed portion G2. Slits are formed on both sides of each of the locking portion 22e and the locking portion 22f, whereby the locking portion 22e and the locking portion 22f can be elastically deformed. The magnets 21a, 21b are accommodated in the recessed portions G1, G2 in a state where the locking portions 22e, 22f are bent outward. The magnets 21a, 21b accommodated in the recessed portions G1, G2 have their outer edge portions locked by the elastic restoring force of the locking portions 22e, 22f.

[0027] As shown in FIG. 3, the arm support portion 23 includes a first arm insertion hole 24a, a second arm insertion hole 24b, a first arm retainer 25a, a second arm retainer 25b, an arm hook 26, wall portions 27a, 27b, and a hook protection wall 28.

[0028] The first arm insertion hole 24a and the second arm insertion hole 24b are configured such that the inserted end portion 11a of the arm 11 can be inserted, and are bottomed holes having a depth in the Z direction. The first arm insertion hole 24a and the second arm insertion hole 24b are spaced apart from each other in the direction in which the straight portion 11c of the arm 11 extends. FIG. 3 shows a state where the inserted end portion 11a of the arm 11 is inserted into the first arm insertion hole 24a. Although not shown, by inserting the inserted end portion 11a of the arm 11 into the second arm insertion hole 24b, the arm 11 can be attached to the arm support portion 23 in a direction opposite to the state shown in FIG. 3.

[0029] The first arm retainer 25a and the second arm retainer 25b are each formed in a hook shape and are configured to press the straight portion 11c of the arm 11 from the +Z direction. The first arm retainer 25a and the second arm retainer 25b are located between the first arm insertion hole 24a and the second arm insertion hole 24b. They are positioned in the order of the second arm retainer 25b and the first arm retainer 25a from the first arm insertion hole 24a toward the second arm insertion hole 24b.

[0030] The arm hook 26 is configured to be hung on the straight portion 11c and has an elastic force in a direction to press the straight portion 11c against the first arm retainer 25a and the second arm retainer 25b. Slits S are formed on both sides of the arm hook 26 in the holder 22 (arm support portion 23). Thereby, the portion of the arm hook 26 in the holder 22 is configured to be easily elastically deformed. Further, the arm hook 26 has an inclined surface 26a whose function will be described later.

[0031] The arm hook 26 is located between the first arm retainer 25a and the second arm retainer 25b. Between the first arm insertion hole 24a and the second arm insertion hole 24b, the second arm retainer 25b, the arm hook 26, and the first arm retainer 25a are located. The first arm insertion hole 24a and the second arm retainer 25b, and the second arm insertion hole 24b and the first arm retainer 25a, which sandwich the arm hook 26, are configured in a symmetric arrangement about the arm hook 26 in the direction in which the straight portion 11c extends.

[0032] As shown in Fig. 3, when attaching the arm 11 to the holder 22 in a manner where the inserted end portion 11a is inserted into the first arm insertion hole 24a, while inserting the inserted end portion 11a into the first arm insertion hole 24a, the arm 11 is rotated about the first arm insertion hole 24a from the outside of the arm hook 26 toward the arm hook 26 (in the example of Fig. 3, a counterclockwise rotation about the first arm insertion hole 24a). In the process of rotating the arm hook 26 in this way, the straight portion 11c slides on the inclined surface 26a of the arm hook 26 while pushing the arm hook 26 downward in the -Z direction. As a result, the straight portion 11c can be inserted between the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b. When the straight portion 11c crosses over the inclined surface 26a and reaches a position where it is held by the first arm retainer 25a and the second arm retainer 25b, the arm hook 26 presses the straight portion 11c against the first arm retainer 25a and the second arm retainer 25b by its restoring force. In this way, the straight portion 11c of the arm 11 can be sandwiched between the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b. The movement of the straight portion 11c in the Z direction is restricted by the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b. Also, the first arm retainer 25a and the second arm retainer 25b restrict the movement of the arm 11 in the direction approaching the annular portion 220 (the direction approaching the axis AX), and the arm hook 26 restricts the movement of the arm 11 in the direction away from the annular portion 220 (the direction away from the axis AX). Further, since the inserted end portion 11a is inserted into the first arm insertion hole 24a, the movement of the straight portion 11c of the arm 11 in the extending direction is restricted.

[0033] Although not shown, when attaching the arm 11 to the holder 22 in a manner where the inserted end portion 11a is inserted into the second arm insertion hole 24b, while inserting the inserted end portion 11a into the second arm insertion hole 24b, the arm 11 is rotated around the second arm insertion hole 24b from the outside of the arm hook 26 toward the arm hook 26 (in the example of FIG. 3, a clockwise rotation around the second arm insertion hole 24b). In the process of rotating the arm hook 26 in this way, the straight portion 11c slides on the inclined surface 26a of the arm hook 26 while pushing the arm hook 26 downward in the -Z direction. As a result, the straight portion 11c can be inserted between the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b. When the straight portion 11c gets over the inclined surface 26a and reaches a position where it is pressed by the first arm retainer 25a and the second arm retainer 25b, the arm hook 26 presses the straight portion 11c against the first arm retainer 25a and the second arm retainer 25b by its restoring force. In this way, the straight portion 11c of the arm 11 can be sandwiched between the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b. The movement of the straight portion 11c in the Z direction is restricted by the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b. Also, the first arm retainer 25a and the second arm retainer 25b restrict the movement of the arm 11 in the direction approaching the annular portion 220 (the direction approaching the axis AX), and the arm hook 26 restricts the movement of the arm 11 in the direction away from the annular portion 220 (the direction away from the axis AX). Further, since the inserted end portion 11a is inserted into the second arm insertion hole 24b, the movement of the straight portion 11c of the arm 11 in the extending direction is restricted.

[0034] As described above, according to the liquid level detection device 1, the arm 11 can be easily attached to the holder 22 (arm support portion 23), and the arm 11 is stably supported by the holder 22. And since it is possible to prevent the arm 11 from coming off the holder 22 without using a push nut, it is also possible to reduce the number of parts.

[0035] The wall portion 27a is positioned opposite to the first arm retainer 25a. Also, the wall portion 27b is positioned opposite to the second arm retainer 25b. The wall portions 27a and 27b are in a direction rotatable about the first arm insertion hole 24a or the second arm insertion hole 24b, and restrict the movement of the arm 11 in a direction away from the first arm retainer 25a and the second arm retainer 25b. As shown in FIG. 3, when the inserted end portion 11a of the arm 11 is inserted into the first arm insertion hole 24a, when an external force in a direction in which the arm 11 comes out of the holder 22 (counterclockwise direction about the first arm insertion hole 24a) is applied to the arm 11, the arm 11 contacts the wall portion 27a, whereby the forces applied to the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b are dispersed. In this way, according to the wall portion 27a, it is possible to prevent the arm 11 from coming off from the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b. On the other hand, although not shown, when the inserted end portion 11a of the arm 11 is inserted into the second arm insertion hole 24b, when an external force in a direction in which the arm 11 comes out of the holder 22 (in this case, clockwise direction about the second arm insertion hole 24b) is applied to the arm 11, the arm 11 contacts the wall portion 27b, whereby the forces applied to the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b are dispersed. In this way, according to the wall portion 27b, it is possible to prevent the arm 11 from coming off from the arm hook 26, the first arm retainer 25a, and the second arm retainer 25b.

[0036] The hook protection wall 28 is positioned between the wall portion 27a and the wall portion 27b and faces the arm hook 26. The hook protection wall 28 has a substantially U shape when viewed from the +Z direction and is provided outside the wall portion 27a and the wall portion 27b. Similar to the above, when an external force in a direction in which the arm 11 comes out of the holder 22 is applied to the arm 11, if the arm hook 26 extends, the arm hook 26 hits the hook protection wall 28, thereby suppressing damage to the arm hook 26. In this way, the hook protection wall 28 can suppress damage to the arm hook 26.

[0037] The magnetic detection element 30 shown in FIG. 2 detects changes in the magnetic field associated with the rotation of the rotating part 20. As the magnetic detection element 30, for example, a Hall IC (Integrated Circuit) including a Hall element, an operational amplifier, etc. can be applied. The magnetic detection element 30 outputs a detection signal (for example, a voltage signal) corresponding to the strength of the detected magnetic field (magnetic flux density) to the PCB 60. Since the magnetic field formed by the magnets 21a and 21b changes due to the rotation of the rotating part 20, the detection signal indicates a value corresponding to the position of the float 10 that rotates the rotating part 20, that is, the position of the liquid surface. Note that the magnetic detection element 30 may be other known magnetic detection elements using an MR (Magneto Resistive Sensor) element or the like.

[0038] The case 40 is, for example, an injection molded product formed of a synthetic resin material, supports the rotating part 20 rotatably, and houses the magnetic detection element 30. As shown in FIG. 2, the case 40 has a base part 41 and a shaft part 42. The base part 41 is located on the back side (-Z side) of the rotating part 20.

[0039] As shown in the rear perspective view of FIG. 5, the base part 41 has a substrate housing part 41a and a wiring lead-out part 41b. The substrate housing part 41a is a part formed by being recessed in the +Z direction from the back surface of the case 40 and houses the PCB 60 and the like. A mold material (not shown) that fills and covers the PCB 60 is provided in the substrate housing part 41a. The mold material is made of a known material such as epoxy. The mold material is, for example, black. In order to easily determine the filling amount and filling condition of the mold material with respect to the substrate housing part 41a, the color of the case 40 is set to a color different from that of the mold material (for example, white). Note that the colors of the mold material and the case 40 are not limited to this example and are arbitrary as long as they are different enough to be distinguishable from each other.

[0040] The wiring lead-out part 41b is a part from which the wiring part 70 is led out of the case 40 and is formed in communication with the substrate housing part 41a. The wiring lead-out part 41b is located at the +Y direction end of the case 40. A grommet 80 that holds a part of the wiring part 70 is fixed to the wiring lead-out part 41b.

[0041] The grommet 80 is composed of a known elastomer such as nitrile rubber. The grommet 80 is formed with insertion holes through which each of the plurality of cords of the wiring portion 70 passes. As shown in FIG. 5, the wiring portion 70 of the present embodiment is composed of three cords. Therefore, the grommet 80 also has three insertion holes. The grommet 80 has a concave portion corresponding to the convex portion formed in the wiring lead-out portion 41b, and is fitted into the wiring lead-out portion 41b by utilizing these concave and convex shapes. Note that the relationship between the concave and convex may be reversed. The fitting mechanism between the grommet 80 and the wiring lead-out portion 41b can easily position the grommet 80 with respect to the case 40, and prevent the grommet 80 from falling off the case 40.

[0042] Inside the substrate accommodating portion 41a, positioning protrusions P1 and positioning pins P2, P3 that are integrally formed with the base portion 41 and protrude on the back side (in the -Z direction) are provided. The positioning protrusion P1 and the positioning pins P2, P3 are inserted into through holes or cutouts formed in the PCB 60, and are configurations for determining the position of the PCB 60 with respect to the substrate accommodating portion 41a. The positioning protrusion P1 is larger than the positioning pins P2, P3 and is generally formed in a columnar shape. The positioning protrusion P1 is inserted into a through hole provided in the substantially central portion of the PCB 60, and this positioning protrusion P1 is also shared for fixing to an object (for example, a fuel pump) to which the liquid level detection device 1 is attached.

[0043] Here, in the present embodiment, an example of a three-wire type in which the wiring portion 70 is composed of three cords is shown, but the wiring portion 70 may be a two-wire type composed of two cords. When adopting the two-wire type, the substrate accommodating portion 41a according to the modified example shown in FIG. 6 may have a blocking wall 41c that blocks one insertion hole of the grommet 80 so that the grommet 80 used in the three-wire type (that is, the grommet 80 having three insertion holes) can be shared. By this blocking wall 41c, it is possible to prevent the mold material from leaking out from the insertion hole through which the cord does not pass in the grommet 80.

[0044] As shown in FIGS. 2 and 3, the shaft portion 42 protrudes from the base portion 41 in the +Z direction and is formed in a substantially cylindrical shape with the axis AX as the center. The shaft portion 42 is inserted into a through-hole R provided in the holder 22 and has a protruding portion 42a that protrudes from the through-hole R. Further, as shown in the rear-side perspective view of FIG. 7, a space portion 42b as a void is formed inside the shaft portion 42. This space portion 42b is a closed space in which the -Z-direction end is open and communicates with the substrate housing portion 41a, while the +Z-direction end is closed. The shaft portion 42 further has a surrounding portion 42d (see FIGS. 7 and 8) that surrounds the space portion 42b around the axis AX, and an opposing portion 42e (see FIGS. 2 and 3) that opposes the magnetic detection element 30 in the direction in which the axis AX extends. The opposing portion 42e is located on the back side (-Z-direction side) of the protruding portion 42a and is a portion that closes the +Z-direction end of the space portion 42b. The magnetic detection element 30 is disposed (press-fitted and held) in the space portion 42b provided inside the shaft portion 42.

[0045] Here, FIG. 7 is a perspective view of the vicinity of the shaft portion 42 of the case 40 as viewed from the rear side (-Z direction). FIG. 8 is a partial rear view of the shaft portion 42.

[0046] As shown in FIG. 7, a crush rib Q3 is provided along the axis AX on the inner circumference of the surrounding portion 42d that surrounds the space portion 42b. As shown in FIG. 8, the crush rib Q3 abuts on the outer circumference of the magnetic detection element 30 indicated by the broken line. In the present embodiment, four crush ribs Q3 are provided.

[0047] As shown in FIG. 8, the space portion 42b viewed from the -Z direction has a shape formed by combining a trapezoid with its upper base facing the -Y direction and a rectangle having the same length as the lower base and the long side of this trapezoid. And, among the inner circumferences of the surrounding portion 42d (that is, the outer circumferences of the space portion 42b), no crush ribs Q3 are formed on the surfaces corresponding to the upper base and the legs of the trapezoid, and four crush ribs Q3 are formed on the remaining surfaces. Specifically, among the inner circumferences of the surrounding portion 42d, two crush ribs Q3 are formed on the surface facing the -Y direction, and one crush rib Q3 is formed on each of the pair of surfaces along the Y direction (the surfaces corresponding to the short sides of the rectangle). The magnetic detection element 30 is press-fitted and fixed into the surrounding portion 42d (space portion 42b) in a manner of being pressed by the four crush ribs Q3 provided in this way.

[0048] When the magnetic detection element 30 is press-fitted into the surrounding portion 42d, the magnetic detection element 30 is pressed against the flat surface corresponding to the upper base of the trapezoid by the two crush ribs Q3 provided on the surface facing the -Y direction among the inner circumferences of the surrounding portion 42d, while the position in the Y direction is determined. Thereby, the position accuracy of the magnetic detection element 30 with respect to the axis AX in the Y direction can be improved. Since the axis AX of the present embodiment is set to be unevenly distributed in the -Y direction rather than the center position of the space portion 42b, it is particularly useful to press the magnetic detection element 30 in the -Y direction by the two crush ribs Q3.

[0049] Also, when the magnetic detection element 30 is press-fitted into the surrounding portion 42d, the magnetic detection element 30 is sandwiched by the crush ribs Q3 provided on each of the pair of surfaces along the Y direction among the inner circumferences of the surrounding portion 42d, while the position in the X direction is determined.

[0050] As shown in FIG. 8, a groove U3 is formed in a part of the opposing portion 42e corresponding to the crash rib Q3. The groove U3 is formed in a concave shape around the end portion of the crash rib Q3 facing in the +Z direction. Four grooves U3 are provided corresponding to each of the four crash ribs Q3. This groove U3 can store the shavings generated by shaving the crash rib Q3 when the magnetic detection element 30 is inserted into the surrounding portion 42d (space portion 42b). Thereby, it is possible to prevent the shavings from accumulating over the entire opposing portion 42e and prevent a decrease in the holding force of the magnetic detection element 30 by the surrounding portion 42d.

[0051] The non-magnetic member 50 shown in FIGS. 1 to 3 is a member that prevents the holder 22 from coming off the shaft portion 42 and is configured in a substantially ring shape (substantially C-shaped) with an end. The non-magnetic member 50 is fitted into an annular groove portion formed on the outer periphery of the protruding portion 42a of the shaft portion 42.

[0052] The PCB 60 mounts a circuit that electrically connects the magnetic detection element 30 and the wiring portion 70. The magnetic detection element 30 is electrically connected to the PCB 60 via a substantially L-shaped terminal 31 extending from the magnetic detection element 30 toward the PCB 60. A wiring portion 70 is connected to an end region of the PCB 60 opposite to the terminal 31 by means such as soldering.

[0053] The wiring portion 70 is configured to transmit a detection signal from the magnetic detection element 30 to the outside. One end of the wiring portion 70 is electrically connected to the PCB 60, and the other end is electrically connected to a control portion (not shown) outside the liquid level detection device 1. The wiring portion 70 is configured by bundling a plurality of cords formed by coating a conductive metal such as copper with an insulating material. The wiring portion 70 includes a signal line for transmitting a detection signal. The control portion is composed of a microcomputer and acquires a detection signal output from the magnetic detection element 30 and transmitted through the terminal 31, the PCB 60, and the wiring portion 70. Then, the control portion calculates the position of the liquid level of the liquid and the amount of the liquid corresponding to the position by a known method based on the acquired detection signal. Note that the control portion may be a configuration provided in the liquid level detection device 1.

[0054] The present invention is not limited by the above embodiments and drawings. Within the scope of not changing the gist of the present invention, modifications (including deletion of components) can be appropriately made.

[0055] In the above, an example in which the holder 22 holds two magnets 21a and 21b has been described. However, as long as a magnetic field can be formed in the magnetic detection element 30, the shape, number, and magnetization direction of the magnets are arbitrary. Further, in the above, an example in which the holder 22 holds the magnets 21a and 21b inserted from the back side thereof has been shown. However, the holder 22 may be configured to hold the magnets 21a and 21b inserted from the front side thereof.

[0056] In the above, an example in which both the first arm insertion hole 24a and the second arm insertion hole 24b are provided in the holder 22 so that the direction of the arm 11 with respect to the holder 22 can be selected has been shown. However, one of the holes may be omitted. For example, when the second arm insertion hole 24b is omitted from the holder 22, the arm support portion 23 of the holder 22 only needs to include at least the first arm insertion hole 24a, the first arm presser 25a, and the arm hook 26. Also, in this case, it is possible to omit the wall portion 27b out of the wall portions 27a and 27b. On the other hand, when the first arm insertion hole 24a is omitted from the holder 22, the arm support portion 23 of the holder 22 only needs to include at least the second arm insertion hole 24b, the second arm presser 25b, and the arm hook 26. Also, in this case, it is possible to omit the wall portion 27a out of the wall portions 27a and 27b.

[0057] In the above description, for the sake of facilitating the understanding of the present disclosure, the description of known technical matters has been appropriately omitted. The liquid level detection device 1 described above has the features of the appended claims listed below.

[0058] (Appended Claims) (Appended Claim 1) A float that floats on a liquid and is displaced according to the position of the liquid level of the liquid, A rotating part having a magnet and a holder that holds the magnet and is rotatable about an axis, A magnetic detection element that detects a change in a magnetic field accompanying rotation of the rotating part; An arm that connects the float and the rotating part and rotates the rotating part in accordance with displacement of the float; The arm has a straight part that extends linearly and an inserted end part that is bent from the straight part and is inserted into the holder. The holder Has an arm insertion hole into which the inserted end part can be inserted; An arm presser that presses the straight part; And an arm hook that is hung on the straight part. The straight part is sandwiched between the arm presser and the arm hook. The arm hook is located between the arm insertion hole and the arm presser. A liquid level detection device.

[0059] (Appendix 2) The holder In addition to the first arm insertion hole that is the arm insertion hole, it has a second arm insertion hole into which the inserted end part can be inserted; In addition to the first arm presser that is the arm presser, it has a second arm presser that presses the straight part. The arm hook is located between the first arm presser and the second arm presser. Between the first arm insertion hole and the second arm insertion hole, the second arm presser, the arm hook, and the first arm presser are located. The liquid level detection device according to Appendix 1.

[0060] (Appendix 3) The holder has a wall part that regulates movement of the arm in a direction that can rotate around the first arm insertion hole or the second arm insertion hole and is away from the first arm presser and the second arm presser. The liquid level position detection device according to Appendix 2.

[0061] (Appendix 4) Slits are formed on both sides of the arm hook in the holder. The liquid level detection device according to any one of Appendices 1 to 3.

[0062] (Appendix 5) The holder has a recess for accommodating the magnet. On the inner periphery of the recess, a crush rib is formed along the axis and in contact with the outer periphery of the magnet. The liquid level detection device according to any one of Appendices 1 to 4.

[0063] (Appendix 6) The liquid level detection device further includes a support member for rotatably supporting the rotating part. The support member has a shaft portion extending along the axis. The magnetic detection element is disposed in a space portion provided on the shaft portion. The holder is provided with a through portion through which the shaft portion can penetrate. The shaft portion has an enclosing portion surrounding the space portion. On the inner periphery of the enclosing portion, a crush rib is formed along the axis and in contact with the outer periphery of the magnetic detection element. The liquid level detection device according to any one of Appendices 1 to 5.

[0064] (Appendix 7) The recess has a bottom corresponding to its bottom. A groove is formed in a part of the bottom corresponding to the crush rib formed on the inner periphery of the recess. The liquid level detection device according to Appendix 5.

[0065] (Appendix 8) The shaft portion has an opposing portion opposing the magnetic detection element in the direction in which the axis extends. A groove is formed in a part of the opposing portion corresponding to the crush rib formed on the inner periphery of the enclosing portion. The liquid level detection device according to Appendix 6.

[0066] The present invention can be implemented in various embodiments and modifications without departing from the broad spirit and scope of the present invention. Also, the above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims rather than the embodiments. And various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

Explanation of Reference Numerals

[0067] 1…Liquid level detection device 10…Float 11…Arm 11a…Inserted end portion, 11b…Holding end portion, 11c…Straight portion 20…Rotating portion 21a, 21b…Magnets 22…Holder, 220…Annular portion, 22e, 22f…Locking portions 23…Arm support portion 24a…First arm insertion hole, 24b…Second arm insertion hole 25a…First arm retainer, 25b…Second arm retainer 26…Arm hook, 26a…Inclined surface 27a, 27b…Wall portions 28…Hook protection wall 30…Magnetic detection element, 31…Terminal 40…Case (an example of a support member) 41…Base portion, 41a…Substrate housing portion, 41b…Wiring lead-out portion, 41c…Blocking wall 42…Shaft portion, 42a…Protruding portion, 42b…Space portion 42d…Surrounding portion 42e…Opposing portion 50…Non-magnetic member 60…PCB 70…Wiring portion 80…Grommet AX…Axis R…Through hole G1, G2…Depressed portions G1a, G2a…Bottom portions Q1, Q2, Q3…Crash ribs U2, U3…Grooves S… Slit P1… Positioning projection, P2, P3… Positioning pins

Claims

1. A float that floats on a liquid and is displaced according to the position of the liquid surface of the liquid, a rotating part having a magnet and a holder for holding the magnet, and being rotatable about an axis, a magnetic detection element that detects a change in a magnetic field accompanying the rotation of the rotating part, and an arm that connects the float and the rotating part and rotates the rotating part according to the displacement of the float. The arm has a straight part that extends linearly and an inserted end part that is an end of a bent part from the straight part and is inserted into the holder. The holder has an arm insertion hole into which the inserted end part can be inserted, an arm presser that presses the straight part, and an arm hook that is hung on the straight part. The straight part is sandwiched between the arm presser and the arm hook. The arm hook is located between the arm insertion hole and the arm presser. A liquid surface detection device.

2. The holder has, in addition to the first arm insertion hole that is the arm insertion hole, a second arm insertion hole into which the inserted end part can be inserted, and, in addition to the first arm presser that is the arm presser, a second arm presser that presses the straight part. The arm hook is located between the first arm presser and the second arm presser. Between the first arm insertion hole and the second arm insertion hole, the second arm presser, the arm hook, and the first arm presser are located. The liquid surface detection device according to Claim 1.

3. The holder has a wall part that regulates the movement of the arm in a direction rotatable about the first arm insertion hole or the second arm insertion hole and away from the first arm presser and the second arm presser. The liquid surface position detection device according to Claim 2.

4. Slits are formed on both sides of the arm hook in the holder. The liquid surface detection device according to any one of Claims 1 to 3.

5. The holder has a recessed part for accommodating the magnet. On the inner periphery of the recessed part, a crush rib is formed along the axis and in contact with the outer periphery of the magnet. The liquid surface detection device according to any one of Claims 1 to 3.

6. The liquid surface detection device further includes a support member that rotatably supports the rotating part. The support member has a shaft part that extends along the axis. The magnetic detection element is disposed in a space part provided in the shaft part. The holder is provided with a through-hole through which the shaft portion can pass. The shaft portion has an enclosing portion that surrounds the space portion. On the inner circumference of the enclosing portion, a crush rib is formed along the axis and abuts against the outer circumference of the magnetic detection element. The liquid level detection device according to any one of claims 1 to 3.

7. The recessed portion has a bottom portion corresponding to its bottom. A groove is formed in a part of the bottom portion corresponding to the crush rib formed on the inner circumference of the recessed portion. The liquid level detection device according to claim 5.

8. The shaft portion has an opposing portion that opposes the magnetic detection element in the direction in which the axis extends. A groove is formed in a part of the opposing portion corresponding to the crush rib formed on the inner circumference of the enclosing portion. The liquid level detection device according to claim 6.

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