JP7765732B2 - Detection device - Google Patents

Description

The present invention relates to a detection device that detects, for example, the level of a liquid.

One example of this type of detection device is disclosed in Patent Document 1. The detection device described in Patent Document 1 comprises a resin magnet holder (rotating member) that houses a magnet and rotates in response to the displacement of a float floating on the surface of the liquid; a magnetic detection element that detects changes in the magnetic field associated with the rotation of the magnet holder; a resin case that rotatably supports the magnet holder and houses the magnetic detection element; and a resin cover that is positioned to cover the magnet holder. The resin cover is welded and fixed to the case by melting four welding protrusions provided at the four corners of the base that forms the main part of the case.

JP 2014-71042 A

In the case of the detection device described in Patent Document 1, the magnet holder, case, and resin cover are all injection-molded products obtained by injection molding resin (molten resin), and to mold the magnet holder, case, and resin cover (i.e., three injection-molded products), a separate mold (i.e., three molds) is required for each component, which increases the cost of parts for manufacturing the detection device and causes an increase in costs.
SUMMARY OF THE INVENTION In order to address the above-mentioned problems, an object of the present invention is to provide a detection device that can suppress increases in costs.

The present invention comprises a rotating member that rotates around an axis in response to the displacement of an object to be detected, a magnet placed in a recess provided in the rotating member, a magnetic detection element that detects changes in the magnetic field that accompany the rotation of the rotating member, a support member that rotatably supports the rotating member, and a non-magnetic member that is arranged to cover at least a portion of the magnet , wherein the support member has a shaft portion that is arranged along the axis, the magnetic detection element is placed in a space provided in the shaft portion, the rotating member is provided with a through portion through which the shaft portion can pass, and the non-magnetic member has a ring portion with ends that surrounds the protruding portion of the shaft portion that protrudes from the through portion, and a plurality of fitting portions that fit into grooves provided in the protruding portion .

The present invention is also characterized in that the ring portion is arranged along an imaginary circumference centered on the axis, and the rotating member has a raised portion formed on the imaginary circumference in correspondence with the missing portion of the ring portion, with a portion of the raised portion fitting into the groove portion.

The present invention is also characterized in that the fitting portions are fitting protrusions partially provided on the inside of the ring portion, and are provided at both end portions of the ring portion and at the middle portion of the ring portion.

The present invention is also characterized in that the inner edge of the magnet is covered by the ring portion, and the outer edge is covered by a locking portion formed on the rotating member.

The present invention is also characterized in that the non-magnetic member rotates in conjunction with the rotation of the rotating member.

The present invention is also characterized by comprising a float that floats on the liquid to be detected and displaces along with the liquid surface, and an arm that connects the float to the rotating member and rotates the rotating member in response to the displacement of the float.

The present invention provides a detection device that can achieve the intended purpose and prevent cost increases.

FIG. 2 is a front view of the detection device according to the present embodiment. FIG. 2 is an exploded perspective view of the detection device according to the embodiment. 2 is a cross-sectional view taken along the line AA in FIG. 1; 2 is a cross-sectional view taken along the line B-B in FIG. 1; 2 is a diagram showing the rotating member and the support member as viewed from the direction of arrow C in FIG. 1 . FIG. 10 is a front view of the detection device according to the embodiment when the position of the float arm is changed. 6 is a cross-sectional view taken along the line DD in FIG. 5; 8 is a diagram showing a state in which the first rib is cut off in FIG. 7 .

One embodiment of the present invention will be described with reference to the drawings.

The detection device F shown in Figure 1 is configured as a liquid level detection device that detects the position (liquid level) of the liquid surface La of the liquid L contained in a tank (not shown). The liquid surface La displaces vertically depending on the increase or decrease in the amount of the liquid L. For example, the detection device F is attached to a vehicle fuel tank and detects the liquid level corresponding to the amount of gasoline used as the liquid L.

In the following, the components of the detection device F may be described using the mutually orthogonal X, Y, and Z axes as appropriate. The Y axis is along the vertical direction in Figure 1. The Z axis is parallel to the axis AX, which will be described later. Furthermore, the direction indicated by the arrows indicating each of the X, Y, and Z axes is the + (plus) direction of each axis, and the opposite direction is the - (minus) direction.

As shown in the appropriate drawings in Figures 1 to 7, the detection device F comprises a float 10, an arm 11, a rotating member 20 that rotates around an axis AX, a magnetic detection element 30, a case 40 serving as a support member, a non-magnetic member 50, a PCB (Printed Circuit Board) 60, a wiring section 70, a grommet 80, and a molding material 90.

As shown in Figure 1, the float 10 floats in the liquid L to be detected and displaces along with the liquid surface La. The float 10 is made of, for example, synthetic rubber.

The arm 11 connects the float 10 and the rotating member 20, and rotates the rotating member 20 around the axis AX in response to the displacement of the float 10. The arm 11 is made of a non-magnetic metal, and holds the float 10 at one end, with the other end attached to the rotating member 20.

The arm 11 has a first portion 11a that is inserted into the float 10 and engages with a first arm engaging portion (described below) provided on the rotating member 20; a second portion 11b that bends at a substantially right angle from one end of the first portion 11a and engages with a second arm engaging portion (described below) provided on the rotating member 20; and a third portion 11c that bends at a substantially right angle from the other end of the first portion 11a opposite the one end and connects to the float 10. Note that the float 10 and arm 11 are not shown in Figure 2.

The rotating member 20 rotates around the axis AX in response to the displacement of the detection target, and has two magnets 21a and 21b and a magnet holder 22 that holds the magnets 21a and 21b (see Figures 2 and 4). The rotating member 20 generates a magnetic field using the magnets 21a and 21b that can be detected by the magnetic detection element 30. This magnetic field changes as the rotating member 20 rotates.

Magnets 21a and 21b are made of known materials such as neodymium or ferrite, and are each placed in a recess, described below. Magnets 21a and 21b are each magnetized with two poles in the radial direction around axis AX, for example, so that a magnetic field is generated between them. Magnets 21a and 21b are each formed along an arc around axis AX, and face each other in the radial direction around axis AX.

The magnet holder 22 is an injection-molded product made from, for example, a synthetic resin material, and is formed in a generally circular ring shape. The magnet holder 22 includes a main body 22a, first and second arm engaging portions 22b and 22c, a raised portion 22d, flexible engaging portions 22e and 22f, and multiple ribs 22g.

The main body 22a constitutes the main part of the magnet holder 22 and has recesses G1 and G2, a recess H1 provided on the bottom surface facing the case 40 (the surface facing the -Z direction), and a through-hole R.

Recesses G1 and G2 are provided to accommodate magnets 21a and 21b, and as shown in Figures 2 and 4, are recessed in the -Z direction. Magnet 21a is accommodated (e.g., press-fitted) in recess G1. Magnet 21b is accommodated (e.g., press-fitted) in recess G2.

As shown in Figures 3 and 4, recess H1 is a portion recessed in a direction away from the case 40. As shown in Figures 3 and 7, recess H1 is annular in shape with the axis AX as its center. The function of recess H1 will be described later. Penetration R is a portion through which the shaft portion (described later) provided on the case 40 can pass. It is provided along the axis AX and is configured as a circular through-hole that penetrates the front and back of the main body portion 22a.

As shown in Figures 1 and 2, the first arm locking portion 22b and the second arm locking portion 22c are provided on the outer periphery of the main body portion 22a. In this embodiment, the first arm locking portion 22b is configured as a portion that can lock the first portion 11a of the arm 11, and the second arm locking portion 22c is configured as a portion that can lock the second portion 11b of the arm 11. The first and second arm locking portions 22b, 22c are located on the side facing the +Z direction from the first and second restriction portions (described below) provided on the case 40. Note that a groove J1 is formed in the first arm locking portion 22b on the side facing the -Z direction, and the first portion 11a is engaged with the first arm locking portion 22b by fitting into this groove J1. Meanwhile, a groove J2 is formed in the second arm locking portion 22c on the side facing the +Z direction, and the second part 11b is fitted into this groove J2, thereby being locked to the second arm locking portion 22c.

In this embodiment, the swing direction of the arm 11 can be changed in response to the displacement of the liquid level La and the float 10, taking into account the shape of the tank containing the liquid L. Specifically, as shown in FIG. 6, the first portion 11a is engaged with the second arm engaging portion 22c, and the second portion 11b is engaged with the first arm engaging portion 22b, thereby changing the swing direction of the arm 11 in response to the shape of the tank. By making the formation width K1 of the first arm engaging portion 22b along the direction of the arm 11 shorter than the formation width K2 of the second arm engaging portion 22c along the direction of the arm 11, it becomes easy to visually check for misassembly of the arm 11 (see FIGS. 1 and 6).

The raised portion 22d is a protruding rib provided on the side facing the +Z direction from the main body portion 221, and is formed in a roughly arc shape so as to cover a missing portion (described below) provided in the non-magnetic member 50.

Engagement portions 22e and 22f are provided on portions of the outer periphery of recesses G1 and G2, respectively, provided in the rotating member 20. Engagement portion 22e covers and engages outer edge portion W3 of magnet 21a housed in recess G1. It has a locking claw E1 that engages outer edge portion W3 and a flexible elastic piece E2 located outside magnet 21a (see Figures 2 and 4). Similarly, engagement portion 22f covers and engages outer edge portion W4 of magnet 21b housed in recess G2. It has a locking claw E3 that engages outer edge portion W4 and a flexible elastic piece E4 located outside magnet 21b. Engagement portion 22e is spaced from recess G1 by a slit M1 formed around its periphery. Engagement portion 22f is spaced from recess G2 by a slit M2 formed around its periphery. With this configuration, the locking portions 22e, 22f formed integrally with the rotating member 20 are flexible and deformable, allowing the magnets 21a, 21b to be accommodated in the recesses G1, G2 with the locking portions 22e, 22f (elastic pieces E2, E4) bent outward. Once accommodated, the outer edge portions W3, W4 of the magnets 21a, 21b can be locked by the elastic restoring force of the locking portions 22e, 22f.

A plurality of ribs 22g are provided between the first and second restricting portions provided on the case 40. As shown in FIG. 5, for example, five ribs 22g are provided at equal intervals between the first and second restricting portions and generally aligned along the X direction. In this embodiment, the ribs are referred to as the first rib R1, second rib R2, third rib R3, fourth rib R4, and fifth rib R5 from left to right in FIG. 5. The ribs R are configured to be able to come into contact with either the first or second restricting portion when the rotating member 20 rotates, and function to determine the rotation angle of the arm 11.

For example, when the first rib R1, second rib R2, third rib R3, fourth rib R4, and fifth rib R5 are all present, if the rotating member 20 rotates in the clockwise direction N1 shown in Figures 2 and 7, the first rib R1 will come into contact with the first restriction portion, thereby restricting the rotation of the rotating member 20. The rotation angle of the arm 11 at this time is angle P1 shown in Figure 7. On the other hand, when the first rib R1, second rib R2, third rib R3, fourth rib R4, and fifth rib R5 are all present, if the rotating member 20 rotates in the counterclockwise direction N2, which is the opposite direction to the clockwise direction N1, the fifth rib R5 will come into contact with the second restriction portion, thereby restricting the rotation of the rotating member 20. The rotation angle of the arm 11 at this time is angle P2 shown in Figure 7.

In this embodiment, the rotation angle of the arm 11 is configured to be changeable. For example, if the first rib R1 of the first rib R1, second rib R2, third rib R3, fourth rib R4, and fifth rib R5 is cut and rib 22g is configured with the second rib R2, third rib R3, fourth rib R4, and fifth rib R5, when the rotating member 20 rotates in the clockwise direction N1 shown in Figures 2 and 7, the second rib R2 abuts against the first restricting portion, restricting the rotation of the rotating member 20. The rotation angle of the arm 11 at this time becomes angle P3, which is larger than the above-mentioned angle P1. In this way, in this embodiment, the rotation angle of the arm 11 can be changed using rib 22g.

The magnetic detection element 30 shown in FIG. 2 detects changes in the magnetic field that accompany the rotation of the rotating member 20. The magnetic detection element 30 can be, for example, a Hall IC (Integrated Circuit) including a Hall element, an operational amplifier, etc. The magnetic detection element 30 outputs a detection signal (e.g., a voltage signal) to the PCB 60 that corresponds to the strength of the detected magnetic field (magnetic flux density). Because the magnetic field formed by the magnets 21a and 21b changes with the rotation of the rotating member 20, the detection signal indicates a value that corresponds to the position of the float 10 that rotates the rotating member 20, i.e., the position of the liquid level La. Note that the magnetic detection element 30 may also be another known magnetic detection element that uses an MR (Magneto-Resistive Sensor) element, etc.

The case 40 is an injection-molded product made of, for example, a synthetic resin material, and rotatably supports the rotating member 20 and houses the magnetic detection element 30. The case 40 has a base portion 41, a shaft portion 42, and first and second restriction portions 43a and 43b.

The base 41 has a generally rectangular shape as shown in FIG. 2, and is located on the bottom surface (surface facing the -Z direction) of the rotating member 20 as shown in FIG. 3. The base 41 has a protrusion 41a provided on the side of the mounting surface on which the rotating member 20 is placed, and a board accommodating portion 41b and a wiring lead-out portion 41c formed on the bottom surface.

The protrusion 41a protrudes in the +Z direction from the mounting surface of the base 41 and is inserted into the recess H1 provided in the rotating member 20. As shown in Figures 2 and 3, the protrusion 41a has an annular shape centered on the axis AX.

When the rotating member 20 rotates in the clockwise direction N1 or counterclockwise direction N2, the recessed portion H1 slides against the protruding portion 41a of the case 40, guiding the rotational movement of the rotating member 20. The protruding portion 41a has a trapezoidal cross section in the radial direction centered on the axis AX. This cross-sectional shape reduces contact resistance when the recessed portion H1 slides over the protruding portion 41a. The rotating member 20 rotates with the protruding portion 41a on the case 40 inserted into the recessed portion H1, preventing the rotating member 20 from shifting in a direction perpendicular to the axis AX (radial direction). Rotation of the rotating member 20 at an angle relative to the axis AX is also prevented. As a result, wear on parts and a decrease in detection accuracy are reduced. Furthermore, the rotating member 20 and case 40 with this structure are highly durable even when subjected to external forces via the arm 11.

The board accommodating section 41b is recessed from the bottom surface of the case 40 in the +Z direction and accommodates a PCB 60 and other components. The board accommodating section 41b is filled with a molding material 90. Note that the molding material 90 is not shown in Figure 2.

The wiring pull-out portion 41c is the portion from which the wiring portion 70 is pulled out of the case 40, and is formed in communication with the board accommodating portion 41b. The wiring pull-out portion 41c is located at the end of the case 40 in the +Y direction. A grommet 80 that holds a portion of the wiring portion 70 is fixed to the wiring pull-out portion 41c as described below.

The shaft 42 protrudes from the base 41 in the +Z direction and is arranged along the axis AX. The shaft 42 here is formed in a roughly cylindrical shape and is inserted (thrusts through) a through-hole R provided in the main body 22a (rotating member 20), with a protruding portion 42a protruding from the through-hole R. The rotating member 20 rotates around the shaft 42. The magnetic detection element 30 is positioned (press-fitted) in a space 42b, which is a void provided inside the shaft 42. This space 42b is a closed space with an open end in the -Z direction that communicates with the substrate accommodating portion 41b and a closed end in the +Z direction.

The first and second restricting portions 43a, 43b are portions for restricting the rotation angle of the arm 11 and are provided on the outer periphery of the base portion 41 (see Figure 2). As shown in Figures 5 and 7, the first and second restricting portions 43a, 43b are located in the -Z direction of the rotating member 20 (arm 11), with the first restricting portion 43a being provided near the first rib R1 and the second restricting portion 43b being provided near the fifth rib R5.

As shown in FIG. 4, the non-magnetic member 50 is positioned to cover the inner edge portions W1 and W2 of the magnets 21a and 21b, which are part of the magnets 21a and 21b. These inner edge portions W1 and W2 are configured as portions of the magnets 21a and 21b located near the shaft portion 42. The non-magnetic member 50 includes a ring portion 51 with ends surrounding the protruding portion 42a of the shaft portion 42 that protrudes from the through-hole R, and multiple fitting portions 52 that fit into the annular groove portion 42c provided in the protruding portion 42a. In this embodiment, both the fitting portions 52 and the raised fitting portion S of the raised portion 22d located on the shaft portion 42 side are configured to fit into the groove portion 42c (see FIG. 3). Note that this raised fitting portion S corresponds to part of the raised portion 22d described in the claims below.

In this case, the ring portion 51 can be a generally C-shaped ring with a missing portion T, which is provided along an imaginary circumference V (see Figure 1) centered on the axis AX. The raised portion 22d of the rotating member 20 is located at this missing portion T. In other words, in this embodiment, as shown in Figure 2, the raised portion 22d is a raised portion on the imaginary circumference V that corresponds to the missing portion T where the ring portion 51 is missing.

The fitting portion 52 is a fitting protrusion partially provided on the inside of the ring portion 51, and has a raised shape that protrudes toward the inside of the ring portion 51. The fitting portions 52 are provided at both end portions of the ring portion 51 and at the center of the ring portion 51. When the rotating member 20 rotates, the fitting portion 52 and raised fitting portion S rotate while fitted into the groove portion 42c. In other words, the non-magnetic member 50 rotates in conjunction with (synchronized with) the rotation of the rotating member 20.

In this case, the ring portion 51 of the non-magnetic member 50 covers the inner edge portions W1 and W2 of the magnets 21a and 21b in the Z direction. Furthermore, the locking claws E1 and E3 (locking portions 22e and 22f) cover the outer edge portions W3 and W4 of the magnets 21a and 21b in the Z direction. In other words, in this embodiment, the inner edge portions W1 and W2 of the magnets 21a and 21b are covered by the ring portion 51, and the outer edge portions W3 and W4 are covered by the locking claws E1 and E3 (locking portions 22e and 22f) integrally formed on the rotating member 20. This allows the non-magnetic member 50 to restrict the position of the magnets 21a and 21b in the direction along the axis AX, providing a retaining function that prevents the magnets 21a and 21b from coming loose from the rotating member 20.

The PCB 60 shown in Figures 2 and 3 implements a circuit that electrically connects the magnetic detection element 30 and the wiring section 70, and is housed in the board housing section 41b of the case 40. The magnetic detection element 30 is electrically connected to the PCB 60 via a substantially L-shaped terminal 31 that extends from the magnetic detection element 30 toward the PCB 60. The PCB 60 has a connection section 61 to which the wiring section 70 is connected, located at a position away from the terminal 31 in the radial direction centered on the axis AX. The wiring section 70 is connected to the connection section 61 by soldering or the like.

The wiring unit 70 is configured to transmit the detection signal from the magnetic detection element 30 to the outside. One end of the wiring unit 70 is electrically connected to the PCB 60, and the other end is electrically connected to a control unit (not shown) located outside the detection device F. The wiring unit 70 is configured by bundling together multiple cords made of a conductive metal such as copper coated with an insulating material.

The wiring unit 70 includes a signal line that transmits the detection signal. The control unit is made up of a microcomputer and acquires the detection signal output from the magnetic detection element 30 and transmitted via the terminal 31, PCB 60, and wiring unit 70. Based on the acquired detection signal, the control unit then calculates the position of the liquid surface La of the liquid L and the amount of liquid L corresponding to that position using a known method. The control unit may also be provided in the detection device F.

The grommet 80 is made of a known elastic material such as nitrile rubber and is attached to the wiring lead-out portion 41c of the case 40. The grommet 80 has insertion holes for passing each of the multiple cords of the wiring portion 70. The grommet 80 acts as a buffer against bending of the wiring portion 70 at the lead-out portion. As shown in FIG. 4, the grommet 80 has recesses corresponding to the protrusions formed on the wiring lead-out portion 41c, and these recesses and protrusions are used to fit into the wiring lead-out portion 41c. However, the relationship of the protrusions and recesses may be reversed. In other words, the grommet 80 may have protrusions and the wiring lead-out portion 41c may have recesses. The mating mechanism between the grommet 80 and the wiring lead-out portion 41c facilitates positioning of the grommet 80 relative to the case 40 and prevents the grommet 80 from falling off the case 40.

The molding material 90 shown in Figure 4 is made of a known material such as epoxy, and is filled into the board accommodating portion 41b, covering the PCB 60 (see Figure 2). The molding material 90 is, for example, black. To make it easier to determine the amount and degree of filling of the molding material 90 in the board accommodating portion 41b, the color of the case 40 is set to a different color (for example, white) from that of the molding material 90. Note that the colors of the molding material 90 and the case 40 are not limited to this example and can be any color as long as they are different enough to be distinguishable from each other.

As described above, this embodiment comprises a rotating member 20 that rotates around axis AX in response to the displacement of the detection target, magnets 21a and 21b disposed in recesses G1 and G2 provided in the rotating member 20, a magnetic detection element 30 that detects changes in the magnetic field associated with the rotation of the rotating member 20, and a non-magnetic member 50 disposed to cover a portion of the magnets 21a and 21b. Therefore, by using a non-magnetic member 50 that is not injection-molded instead of the injection-molded resin cover that has been used in the past, the number of injection-molded parts is reduced compared to the past. This reduces the number of molds required to obtain the injection-molded parts (reducing the number of injection-molding steps), lowers the cost of parts required to manufacture the detection device, and helps prevent cost increases.

Furthermore, in this embodiment, the non-magnetic member 50 includes an open-ended ring portion 51 that surrounds the protruding portion 42a of the shaft portion 42 that protrudes from the through-hole R, and multiple fitting portions 52 that fit into grooves 42c provided in the protruding portion 42a. This reduces the contact area between the non-magnetic member 50 and the shaft portion 42, which has the advantage of improving the durability of the non-magnetic member 50, which rotates in synchronization with the rotation of the rotating member 20.

Furthermore, in this embodiment, the rotating member 20 has a raised portion 22d formed on the imaginary circumference V in a position corresponding to the missing portion T where the ring portion 51 is missing. The raised mating portion S, which is a part of the raised portion 22d, is fitted into the groove portion 42c, thereby allowing the non-magnetic member 50 (multiple mating portions 52) to slide stably within the groove portion 42c, which has the advantage of further improving the durability of the non-magnetic member 50.

The present invention is not limited to the above-described embodiments and drawings. Modifications (including the elimination of components) may be made as appropriate within the scope of the present invention without departing from its spirit.

In the above, the magnets 21a, 21b are configured so that their inner edge portions W1, W2 are covered by the ring portion 51, and their outer edge portions W3, W4 are covered by the locking claws E1, E3 (locking portions 22e, 22f) formed on the rotating member 20. However, for example, the locking claws E1, E3 may be omitted, and the entire magnets 21a, 21b, or most of the magnets 21a, 21b, may be covered by the ring portion 51 (non-magnetic member 50). The key is that the non-magnetic member 50 needs to be positioned so as to cover at least a portion of the magnets 21a, 21b. If the locking claws E1, E3 are omitted, it is preferable to press-fit and fix the magnets 21a, 21b using the elastic pieces E2, E4.

In the above, an example has been shown in which the convex portion 41a provided on the case 40 forms a ring shape centered on the axis line AX, but this shape is not limited to this. For example, the convex portion 41a may have multiple portions arranged intermittently along the circumferential direction centered on the axis line AX. It is preferable that the multiple portions be arranged at equal intervals in the circumferential direction centered on the axis line AX to stably guide the rotational movement of the rotating member 20.

The above describes an example in which the magnet holder 22 holds two magnets 21a and 21b, but the shape, number, and magnetization direction of the magnets are arbitrary as long as they can form a magnetic field in the magnetic detection element 30.

In Figure 3, an example is shown in which the magnetic detection element 30 is positioned on the axis AX, but the placement of the magnetic detection element 30 is arbitrary as long as the detection device F can accurately detect the position of the detection target. For example, the magnetic detection element 30 may be positioned off the axis AX.

In the above explanation, explanations of well-known technical matters have been omitted as appropriate to facilitate understanding of the present invention.

REFERENCE SIGNS LIST 10 Float 11 Arm 20 Rotating member 21a, 21b Magnet 22 Magnet holder 22a Main body 22b First arm locking portion 22c Second arm locking portion 22d Raised portion 22e, 22f Locking portion 22g Rib 30 Magnetic detection element 40 Case (support member)
41 Base portion 42 Shaft portion 42a Protruding portion 42b Space portion 42c Groove portion 50 Non-magnetic member 51 Ring portion 52 Fitting portion 60 PCB
70 Wiring section 80 Grommet 90 Molding material AX Axis line G1, G2 Depression section H1 Recess R Penetration section T Missing section V Virtual circumference

Claims (6)

a rotating member that rotates around an axis in response to the displacement of the detection target;
a magnet disposed in a recess provided in the rotating member;
a magnetic detection element that detects a change in a magnetic field caused by rotation of the rotary member;
a support member that rotatably supports the rotary member;
a non-magnetic member disposed so as to cover at least a portion of the magnet ;
the support member has a shaft portion provided along the axis line,
the magnetic detection element is disposed in a space provided in the shaft portion,
The rotary member is provided with a through-hole through which the shaft portion can pass,
The non-magnetic member is characterized in that it has an end-shaped ring portion surrounding the protruding portion of the shaft portion that protrudes from the through portion, and a plurality of fitting portions that fit into grooves provided in the protruding portion . the ring portion is provided along a virtual circumference having the axis as its center,
the rotating member includes a raised portion formed on the virtual circumference in a manner corresponding to a missing portion of the ring portion,
2. The detection device according to claim 1 , wherein a portion of the raised portion is fitted into the groove portion. 2. The detection device according to claim 1 , wherein the fitting portion is a fitting protrusion partially provided on the inside of the ring portion, and is provided at both end portions of the ring portion and at a middle portion of the ring portion. 3. The detection device according to claim 1 , wherein the magnet has an inner edge portion covered by the ring portion and an outer edge portion covered by a locking portion formed on the rotating member . 5. The detection device according to claim 1 , wherein the non-magnetic member rotates in conjunction with the rotation of the rotary member. a float that floats on the liquid to be detected and displaces together with the liquid surface;
6. The detection device according to claim 1, further comprising an arm that connects the float and the rotary member and rotates the rotary member in response to displacement of the float.