JP2014219316A - Liquid level detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level detector improved in resistance to magnetic noise acting from the outside.SOLUTION: A liquid level detector 100 is provided with a primary float 60 and a secondary float 70 which are formed so as to float in washer liquid. The primary float 60 is attached to a frame 20 fixed to a washer tank 90 so as to be displaced vertically along a gravity direction. The secondary float 70 is attached to the primary float 60 so as to be displaced vertically. A reed switch axis 23 of the frame 20 stores therein a reed switch 40 that switches from an on-state to an off-state when a magnet 50 approaches.

Description

  The present invention relates to a liquid level detection device used for a container for storing a liquid.

  Conventionally, for example, Patent Document 1 discloses a liquid level detection device including a float formed to float in a liquid, a magnet held in the float, and a reed switch that switches from an off state to an on state by the proximity of the magnet. Has been. In this liquid level detection device, the float is assembled to a main body fixed to the container, and is movable up and down along the direction of gravity.

Japanese Utility Model Publication No. 63-101828

  Now, in the liquid level detection device as in Patent Document 1, the magnet held in the float can be separated from the reed switch accommodated in the main body only by the stroke amount by which the float can be displaced with respect to the main body. Therefore, it has been difficult to secure the distance between the magnet and the reed switch.

  Here, the liquid level detection device can be used in an environment that receives the action of magnetic noise from the outside. As a result, the direction of the magnetic field generated by the magnet may coincide with the direction of magnetic noise acting from the outside. In this case, the magnetic field of the magnet is strengthened by magnetic noise. For this reason, in a liquid level detection device in which the distance between the magnet and the reed switch is insufficient, even if the magnet is farthest from the reed switch, the reed switch cannot be switched from the on state to the off state. End up.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid level detection device with improved resistance to magnetic noise acting from the outside.

  In order to achieve the above object, the invention described in claim 1 includes a stationary body (20) fixed to a container (90) for storing a liquid, a floating body that floats on the liquid, and is assembled to the stationary body. A primary float (60, 260) that can be displaced up and down along the direction of gravity, and a secondary float (70, 270) that is formed to float on the liquid and is assembled to the primary float and can be displaced up and down relative to the primary float. And a magnet mechanism (50) that moves up and down by being held by the secondary float, and a switch mechanism (40 that switches from the off state to the on state by the proximity of the magnet body that is held by the fixed body and generates a magnetic field. ).

  According to the present invention, the secondary float holding the magnet body can be further displaced up and down relative to the primary float assembled to the fixed body so as to be displaced up and down. Therefore, the magnet body is a switch held by the fixed body for a distance equal to or more than the sum of the stroke amount by which the primary float can be displaced relative to the fixed body and the stroke amount by which the secondary float can be displaced relative to the primary float. Can be spaced from the mechanism. Thus, the distance between the magnet body and the switch mechanism can be secured, so that even if the direction of the magnetic field generated by the magnet body matches the direction of the external magnetic noise, the switch mechanism can be separated from the magnet body. Can be switched from on to off. Therefore, it is possible to provide a liquid level detection device with improved resistance to external magnetic noise.

  Note that the reference numbers in the parentheses are merely examples of correspondences with specific configurations in the embodiments to be described later in order to facilitate understanding of the present invention, and limit the scope of the present invention. It is not a thing.

It is a figure which shows the state in which the liquid level detection apparatus by 1st embodiment of this invention was installed in the washer tank. It is a perspective view which shows typically the primary float and secondary float which were mutually assembled | attached. It is a perspective view which shows the structure of a primary float typically. It is a perspective view which shows the structure of a secondary float typically. It is a figure for demonstrating the action | operation of a primary float and a secondary float. It is a figure for demonstrating the action | operation of a primary float and a secondary float. It is a figure which shows the state in which the liquid level detection apparatus by 2nd embodiment of this invention was installed in the washer tank.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description may be abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other part of the configuration. Moreover, not only the combination of the configurations explicitly described in the description of each embodiment, but also the configuration of a plurality of embodiments can be partially combined even if they are not explicitly described, as long as there is no problem in the combination. And the combination where the structure described in several embodiment and the modification is not specified shall also be disclosed by the following description.

(First embodiment)
The liquid level detection device 100 according to the first embodiment of the present invention shown in FIG. 1 is attached to a washer tank 90. The washer tank 90 is mounted, for example, in the engine room of the vehicle and stores washer liquid as a liquid. The liquid level detection device 100 detects a decrease in the liquid level accompanying a decrease in the washer liquid stored in the washer tank 90. The liquid level detection device 100 is inserted into the tank 90 through an opening 91 formed in the washer tank 90.

  First, the configuration of the liquid level detection apparatus 100 will be described. In the following description, the axial direction AD is defined along the direction in which the liquid level detection device 100 is inserted into the opening 91. Further, a vertical direction VD is defined along the gravity direction. A direction substantially orthogonal to the axial direction AD and the vertical direction VD is defined as a width direction WD.

  The liquid level detection device 100 includes a housing 20, a float unit 30, a magnet 50, and a reed switch 40.

  The housing 20 is fixed to the washer tank 90. The housing 20 includes a lid part 21, a reed switch shaft 23, and a restriction part 26. The lid portion 21 is formed larger than the opening 91. The lid 21 liquid-tightly closes the opening 91 from the outside of the washer tank 90. The reed switch shaft 23 extends in a cylindrical shape from the lid portion 21 along the axial direction AD. The reed switch shaft 23 forms a housing chamber 24 that houses the reed switch 40. A flange 25 is formed at the tip of the reed switch shaft 23 in the extending direction. The flange portion 25 is formed in a plate shape whose longitudinal direction is the width direction WD. The restricting portion 26 is a wall portion extending in the vertical direction VD. The restricting portion 26 restricts the rotation of the float portion 30 around the reed switch shaft 23 by contacting the float portion 30.

  The float part 30 is formed of a material having a specific gravity smaller than that of the washer liquid so that it can float on the liquid surface of the washer liquid. Specifically, the float part 30 is formed of a polypropylene resin or the like to which a foaming agent is added. The float part 30 is formed in a columnar shape extending in the axial direction AD. The float portion 30 is provided with a through hole 31 and a convex wall portion 32. The through hole 31 penetrates the float part 30 in the axial direction AD. The inner width of the through hole 31 in the vertical direction VD is set to be larger than the outer width of the flange portion 25 in the width direction WD. On the other hand, the inner width in the width direction WD of the through hole 31 is made smaller than the outer width of the flange portion 25 in the width direction WD. By inserting the reed switch shaft 23 through the through hole 31, the float unit 30 is assembled to the housing 20 and can be displaced vertically with respect to the reed switch shaft 23. The convex wall portion 32 is formed at one end portion close to the lid portion 21 among both end portions in the axial direction AD of the float portion 30. The convex wall part 32 is extended along the up-down direction VD. When the float part 30 tries to rotate around the reed switch shaft 23, the convex wall part 32 maintains the posture of the float part 30 by contacting the restricting part 26.

  The magnet 50 is a permanent magnet such as a ferrite magnet. The magnet 50 has a rectangular cross section and is formed in a prismatic shape extending in the axial direction AD. The magnet 50 is held by the float unit 30 and is located above the reed switch shaft 23. The magnet 50 can move up and down following the liquid level together with the float 30.

  The reed switch 40 is a detection element for detecting the height of the liquid level. The reed switch 40 has a main body portion 43 formed in a cylindrical shape and a pair of leads 41 and 42 extending from both ends of the main body portion 43. The reed switch 40 is accommodated in the accommodating chamber 24 in a posture in which the axial direction of the main body portion 43 is aligned with the axial direction AD. The main body portion 43 is a hollow glass tube and accommodates the end portions of the leads 41 and 42 (hereinafter referred to as “lead end portions”). Each lead end portion is provided so as to be able to bend, and faces each other with a predetermined interval. When a magnetic field is applied to the leads 41 and 42 from the outside, the lead ends are attracted to each other by being magnetized to different magnetic poles. When the lead ends contact in this manner, the reed switch 40 is turned on so that it can be conducted between the leads 41 and 42.

  In the liquid level detection device 100 described above, when the liquid level of the washer liquid is sufficiently high, the float unit 30 is displaced upward with respect to the reed switch shaft 23. In this case, since the magnet 50 is separated from the reed switch 40, the reed switch 40 is turned off. On the other hand, when the washer liquid stored in the washer tank 90 is decreased, the float unit 30 is displaced downward (in the direction of gravity) with respect to the reed switch shaft 23. When the magnet 50 approaches the reed switch 40 in this manner, the reed switch 40 is switched from the off state to the on state by the magnetic field generated by the magnet 50.

  Here, in the engine room where the liquid level detection device 100 is installed, there are a large number of magnets incorporated in a prime mover, a generator, and the like. The magnetic force generated by these magnets acts on the liquid level detection device 100 as external magnetic noise. If the direction of the magnetic field by the magnet 50 matches the direction of the magnetic noise, the magnetic field by the magnet 50 is strengthened by the magnetic noise. As a result, even when the magnet 50 is far from the reed switch 40, the reed switch 40 may remain on. The configuration of the float unit 30 for avoiding such a situation will be described below.

  As shown in FIGS. 1 and 2, the float unit 30 includes a primary float 60 and a secondary float 70 that are formed to float on the washer liquid. As shown in FIGS. 2, 3, and 5, the primary float 60 is assembled to the reed switch shaft 23 and can be displaced in the vertical direction VD. The primary float 60 includes a pair of end plate portions 61 and 63, a connecting portion 66, and a plurality of locking claws 68 in addition to the convex wall portion 32 described above.

  The pair of end plate portions 61 and 63 are formed in a disc shape. The end plate portions 61 and 63 are arranged in a posture in which the plate surface direction is aligned with the vertical direction VD and the width direction WD. The end plate portions 61 and 63 are opposed to both end surfaces 71 and 73 in the axial direction AD of the secondary float 70, respectively. Insertion holes 62 and 64 through which the reed switch shaft 23 is inserted are formed in the end plate portions 61 and 63, respectively. One end plate portion 61 facing the end surface 71 close to the flange portion 25 is in contact with the flange portion 25, thereby preventing the float portion 30 from being detached from the reed switch shaft 23. The convex wall portion 32 described above is formed on the other end plate portion 63 facing the end surface 73 close to the restriction portion 26 (see FIG. 1).

  The connecting portion 66 extends from the end plate portion 61 to the end plate portion 63 along the axial direction AD. The connecting portion 66 is formed in a prismatic shape, and connects the end plate portions 61 and 63 to each other. An insertion groove 67 is formed in the connecting portion 66. The insertion groove 67 is formed by denting the connecting portion 66 downward. The insertion groove 67 extends along the axial direction AD and allows the reed switch shaft 23 to be inserted therethrough. The connecting portion 66 contacts the reed switch shaft 23 due to the upward displacement of the primary float 60. The connecting portion 66 supports a plurality of locking claws 68.

  A plurality (four in the first embodiment) of the locking claws 68 are provided in a shape extending upward from the connecting portion 66. Each locking claw 68 is disposed so as to avoid the reed switch shaft 23. A sliding portion 69 is formed at the distal end of each locking claw 68 in the extending direction. The sliding portion 69 projects from the main body portion 68a of the locking claw 68 extending along the vertical direction VD toward the outside in the width direction WD.

  The secondary float 70 shown in FIGS. 2, 4, and 5 is assembled to the primary float 60 and can be displaced in the vertical direction VD with respect to the primary float 60. The secondary float 70 has a shape that extends along the axial direction AD, and is formed in a columnar shape in which the side surface portion is partially missing. The volume of the secondary float 70 is made larger than the volume of the primary float 60. Thereby, the buoyancy acting on the secondary float 70 from the washer liquid is made larger than the buoyancy acting on the primary float 60 from the washer liquid. In the secondary float 70, a holding hole 78, an insertion groove 75, and a plurality of guide grooves 76 are formed.

  The holding hole 78 is provided at the center in the axial direction AD of the secondary float 70 and is located above the reed switch 40. The holding hole 78 is an opening that penetrates the secondary float 70 in the radial direction. The holding hole 78 is formed slightly smaller than the magnet 50. A magnet 50 is embedded in the holding hole 78.

  The insertion groove 75 is formed by denting the secondary float 70 upward. The insertion groove 75 extends from the end surface 71 to the end surface 73 along the axial direction AD. By inserting the reed switch shaft 23 through the insertion groove 75, the secondary float 70 is positioned so as to cover the reed switch shaft 23 from above and sandwich the reed switch shaft 23 from both sides in the width direction WD.

  A plurality of guide grooves 76 (four in the first embodiment) are provided on the side wall 74 forming the insertion groove 75 in an arrangement corresponding to the locking claws 68. Each guide groove 76 extends along the vertical direction VD. Each sliding portion 69 is accommodated in each guide groove 76. The sliding portion 69 slides in the guide groove 76 accommodated by the relative displacement of the secondary float 70 with respect to the primary float 60. When the secondary float 70 is displaced upward with respect to the primary float 60, the locking claw 68 locks the secondary float 70 by bringing the sliding portion 69 into contact with the peripheral wall portion 77 of the guide groove 76. Thus, the upward displacement of the secondary float 70 is restricted. As described above, the guide groove 76 and the sliding portion 69 cooperate to define a range in which the secondary float 70 is relatively displaced with respect to the primary float 60.

  The secondary float 70 described above is accommodated in a space sandwiched between a pair of end plate portions 61 and 63 arranged in the axial direction AD shown in FIG. Thus, the primary float 60 and the secondary float 70 form a float portion 30 having a cylindrical shape. The cross sections of the primary float 60 and the secondary float 70 combined with each other have a circular shape having a smaller diameter than the opening 91 (see FIG. 1). Therefore, the primary float 60 and the secondary float 70 can pass through the opening 91 together. Further, the insertion holes 62 and 64 and the insertion groove 67 of the primary float 60 and the insertion groove 75 of the secondary float 70 form the through hole 31 in the float portion 30.

  Next, the operation of the primary float 60 and the secondary float 70 will be described in detail with reference to FIG.

  When the liquid level is located below the reed switch shaft 23 as the washer liquid decreases, the secondary float 70 is accommodated in the primary float 60 as shown in FIG. 6A. The primary float 60 and the secondary float 70 are suspended from the reed switch shaft 23 by the action of gravity. In this state, since the reed switch 40 is in a state of being close to the magnet 50, it is turned on.

  From the above state, when the liquid level rises due to the replenishment of the washer liquid, the primary float 60 and the secondary float 70 rise together as a result of the buoyancy acting on the floats 60 and 70, as shown in FIG. 6B. The primary float 60 and the secondary float 70 ascend to a position where the bottom of the insertion groove 67 contacts the reed switch shaft 23 from below. In this way, the amount of displacement that the primary float 60 can move upward with respect to the reed switch shaft 23 is defined as a first stroke amount St1.

  When the liquid level of the washer liquid is sufficiently high with respect to the reed switch shaft 23, as shown in FIG. 6C, the secondary float 70 is further displaced relative to the primary float 60 that has been raised to the maximum. As a result, the secondary float 70 continues to rise up to a position where each sliding portion 69 comes into contact with each peripheral wall portion 77 of each guide groove 76 while the reed switch shaft 23 is detached from the insertion groove 75. In this way, the amount of displacement by which the secondary float 70 can move upward with respect to the primary float 60 is defined as a second stroke amount St2.

  According to the first embodiment described so far, the secondary float 70 can be further displaced relative to the primary float 60 in the vertical direction, so the magnet 50 adds the first stroke amount St1 and the second stroke amount St2. The reed switch 40 can be separated by more than the combined distance. Therefore, the distance between the magnet 50 and the reed switch 40 can be secured. As described above, even when the direction of the magnetic field generated by the magnet 50 matches the direction of the external magnetic noise, the reed switch 40 changes from the on state to the off state due to the separation of the magnet 50 as the liquid level rises. It can be switched. Therefore, it is possible to provide the liquid level detection device 100 with improved resistance to external magnetic noise.

  In addition, according to the first embodiment, the volume of the secondary float 70 is larger than the volume of the primary float 60. Therefore, the buoyancy acting on the secondary float 70 is larger than the buoyancy acting on the primary float 60. Therefore, the primary float 60 can be displaced upward with respect to the reed switch shaft 23 while being assisted by the buoyancy of the secondary float 70 (see FIG. 6B). Furthermore, when the primary float 60 is displaced upward as much as possible with respect to the reed switch shaft 23, the secondary float 70 with buoyancy secured can be reliably displaced upward with respect to the primary float 60 (FIG. 6C). reference). As described above, in the configuration in which the float unit 30 is divided into the primary float 60 and the secondary float 70, the buoyancy of the secondary float 70 is ensured, so that the vertical displacement is made following the liquid level. The reliability of the operation of each float 60, 70 can be enhanced. According to the above, since the distance between the magnet 50 and the reed switch 40 is surely ensured, the certainty of the effect of improving the resistance against external magnetic noise is further enhanced.

  If the secondary float 70 is accommodated in the primary float 60 as in the first embodiment, the primary float 60 and the secondary float 70 are integrally inserted into the opening 91 of the washer tank 90. obtain. Therefore, the process of inserting the floats 60 and 70 from the opening 91 into the washer tank 90 becomes easy. Therefore, even with the liquid level detection device 100 with improved resistance to external magnetic noise, the workability of the work related to installation in the washer tank 90 can be maintained high.

  Furthermore, in 1st embodiment, the float which made the primary float 60 and the secondary float 70 integral form by accommodating the secondary float 70 formed in columnar shape between a pair of end-plate parts 61 and 63. FIG. The unit 30 is realized. If it is the above structure, since it becomes easy to ensure the volume of the secondary float 70 with respect to the primary float 60, the buoyancy which acts on the secondary float 70 can also be ensured. As described above, in order to obtain the reliability of the operation of the floats 60 and 70 while ensuring the workability of the work installed in the washer tank 90, the columnar primary float 60 accommodates the columnar secondary float 70. The above-described configuration is preferable.

  In addition, as in the first embodiment, if the reed switch shaft 23 is inserted into the insertion groove 75 formed by recessing the secondary float 70 upward, the magnet 50 held by the secondary float 70 is The reed switch 40 can be reliably approached (see FIG. 6A). Further, when the magnet 50 is separated from the reed switch 40 due to the relative displacement of the secondary float 70, the reed switch shaft 23 can be detached from the insertion groove 75 (see FIGS. 6C and 5). Therefore, the distance between the magnet 50 and the reed switch 40 can be reliably ensured. As described above, the configuration in which the insertion groove 75 that is recessed upward is formed in the secondary float 70 can further increase the certainty of the switching operation of the reed switch 40. Accordingly, the resistance of the liquid level detection device 100 to magnetic noise can be further improved.

  In addition, as in the first embodiment, if the sliding portion 69 is slid in the guide groove 76, the range in which the secondary float 70 is displaced relative to the primary float 60 can be reliably defined. . In such a configuration, the peripheral wall portion 77 and the like for forming the guide groove 76 requires a larger volume than the locking claw 68 and the like for forming the sliding portion 69. Therefore, of the guide groove 76 and the sliding portion 69, the guide groove 76 is provided in the secondary float 70, and the sliding portion 69 is provided in the primary float 60, whereby the volume of the secondary float 70 is reduced to that of the primary float 60. It becomes easy to make it larger than the volume.

  In the first embodiment, the housing 20 corresponds to the “fixed body” described in the claims, the reed switch shaft 23 forms the “cylinder portion” described in the claims, and the reed switch 40 It corresponds to the “switch mechanism” described in the range. Further, the magnet 50 corresponds to a “magnet body” described in the claims, and the washer tank 90 corresponds to a “container” described in the claims.

(Second embodiment)
The second embodiment of the present invention shown in FIG. 7 is a modification of the first embodiment. In the liquid level detection device 200 according to the second embodiment, the reed switch 40 is switched from the on state to the off state as the liquid level drops. In order to realize such an operation, the magnet 50 is installed below the reed switch shaft 23. Hereinafter, details of the operation of the primary float 260 and the secondary float 270 of the second embodiment will be described with reference to FIG.

  When the level of the washer liquid is sufficiently higher than the reed switch shaft 23, the secondary float 270 is accommodated in the primary float 260. The primary float 260 and the secondary float 270 have the bottom portion of the insertion groove 75 in contact with the reed switch shaft 23 from below by buoyancy acting on the floats 260 and 270. In this state, since the reed switch 40 is in a state of being close to the magnet 50, it is turned on.

  From the above state, when the liquid level is lowered due to the decrease of the washer liquid, the primary float 260 and the secondary float 270 are integrally lowered by the action of gravity. Thus, the primary float 260 and the secondary float 270 are lowered to a position where the bottom of the insertion groove 67 contacts the reed switch shaft 23 from above.

  Further, when the level of the washer liquid is lowered, the secondary float 270 is further displaced downward relative to the primary float 260 that has been lowered to the maximum. As a result, the secondary float 270 continues to descend until each slide portion 69 comes into contact with each peripheral wall portion 77 of each guide groove 76 while the reed switch shaft 23 is detached from the insertion groove 75.

  Also in the second embodiment described so far, since the secondary float 270 can be further displaced relative to the primary float 260, the distance between the magnet 50 and the reed switch 40 can be secured. Therefore, the reed switch 40 can be switched from the on state to the off state by the separation of the magnet 50 as the liquid level drops. Accordingly, even in the second embodiment, the resistance to external magnetic noise can be improved.

(Other embodiments)
Although a plurality of embodiments according to the present invention have been described above, the present invention is not construed as being limited to the above embodiments, and can be applied to various embodiments and combinations without departing from the gist of the present invention. can do.

  In the above-described embodiment, since the liquid level detection device is resistant to magnetic noise, the types of liquid level detection devices can be reduced. More specifically, in the conventional liquid level detection device, since the resistance to magnetic noise is insufficient, the direction of the magnetic force generated by the magnet needs to be opposite to the direction of the magnetic noise. With such an arrangement, the magnetic force and magnetic noise of the magnet cancel each other, so that the malfunction of the reed switch due to the magnetic noise is less likely to occur. However, with the above-described measures, it may be necessary to provide a new type in which the magnet mounting direction is changed for each vehicle model to which the liquid level detection device is mounted. On the other hand, in the liquid level detection device according to the above embodiment, resistance to magnetic noise is ensured by increasing the moving range of the magnet. Therefore, regardless of the vehicle type to which the liquid level detection device is attached, the same type of liquid level detection device that holds the magnet in a specific mounting posture can be employed. For these reasons, there is no need to change the direction of the reed switch, the direction of the magnet, etc. for each vehicle type, and the cost of the liquid level detection device can be reduced by reducing the types.

  In the above embodiment, the casing is assembled as a “fixed body” in the opening of the washer tank. However, the configuration corresponding to the “fixed body” may be changed as appropriate. For example, an assembly in which a bracket or the like is combined with the above-described housing may correspond to a “fixed body”.

  In the above embodiment, the prismatic magnet is used as the “magnet body”, but the shape, material, and the like of the configuration corresponding to the “magnet body” may be changed as appropriate. Furthermore, the posture in which the “magnet body” is held may be changed as appropriate. Furthermore, a “magnet body” may be configured by a plurality of magnets. Further, the configuration corresponding to the “switch mechanism” is not limited to the above-described reed switch, and may be changed as appropriate. Furthermore, the configuration corresponding to the “tubular portion” that houses the reed switch is not limited to the cylindrical reed switch shaft 23, and may be changed as appropriate.

  In the said embodiment, the primary float and the secondary float were formed with the foamed polypropylene resin. However, the material of each float is not limited to the above materials, and may be appropriately changed to, for example, a foamed phenol resin. Further, the primary float material and the secondary float material may be different from each other. Furthermore, the part which forms a latching claw and a guide groove, for example may be formed with the material different from the main-body part of each float.

  In the said embodiment, the columnar float part was formed by accommodating a secondary float in a primary float. However, the shape of each float may be changed as appropriate. For example, the primary float may be accommodated in the secondary float. Further, the volume of the primary float may be the same as or larger than the volume of the secondary float. Similarly, the buoyancy acting on the primary float from the liquid may be greater than the buoyancy acting on the secondary float from the liquid.

  In the above embodiment, when the liquid surface height changes, the relative displacement of the primary float relative to the reed switch shaft occurs before the relative displacement of the secondary float relative to the primary float. However, the relative displacement of the secondary float relative to the primary float may occur prior to the relative displacement of the primary float relative to the reed switch shaft. Further, the relative displacement of the secondary float relative to the primary float and the relative displacement of the primary float relative to the reed switch shaft may occur in parallel.

  In the above embodiment, the guide groove 76 and the sliding portion 69 are provided in order to restrict the relative displacement of the secondary float in the direction away from the primary float. The configuration for restricting such displacement is not limited to the above-described configuration, and may be changed as appropriate. For example, the secondary float may be provided with a sliding portion, and the primary float may be provided with a guide groove. Furthermore, the arrangement and number of guide grooves and sliding portions provided in each float are not limited to four, and may be changed as appropriate.

  As described above, the present invention has been described based on the example applied to the liquid level detecting device that detects the height of the level of the washer liquid stored in the vehicle washer tank. However, the application target of the present invention is the liquid of the washer liquid. It is not limited to detection of surface height. The present invention can be applied to a liquid level detection device in a container for other liquids mounted on a vehicle, such as engine oil, brake fluid, engine cooling water, and fuel. Furthermore, the present invention is applicable not only to vehicles but also to liquid level detection devices used in containers for various consumer devices and various transport machines.

AD axis direction, VD vertical direction, 20 housing (fixed body), 23 reed switch shaft (cylinder part), 40 reed switch (switch mechanism), 50 magnet (magnet body), 61, 63 end plate part, 60, 260 Primary float, 66 connecting part, 69 sliding part, 70,270 secondary float, 71, 73 both end faces, 75 insertion groove, 76 guide groove, 90 washer tank (container), 91 opening, 100, 200 liquid level detection device

Claims (7)

A stationary body (20) fixed to a container (90) for storing liquid;
A primary float (60, 260) formed so as to float on the liquid and assembled to the fixed body and displaceable up and down along the direction of gravity;
A secondary float (70, 270) formed to float on the liquid and assembled to the primary float and displaceable up and down with respect to the primary float;
A magnet body (50) that moves up and down by being held by the secondary float;
A liquid level detection apparatus comprising: a switch mechanism (40) that is switched from an off state to an on state by the proximity of the magnet body that is held by the fixed body and generates a magnetic field.   The liquid level detection device according to claim 1, wherein a buoyancy acting on the secondary float from the liquid is larger than a buoyancy acting on the primary float from the liquid.   The liquid level detection device according to claim 1, wherein a volume of the secondary float is larger than a volume of the primary float. A liquid level detection device in which the primary float and the secondary float are inserted into the container through an opening (91) formed in the container,
One of the primary float and the secondary float (60, 260) is configured to pass at least a part of the other so that it can pass through the opening together with the other (70, 270) of the primary float and the secondary float. The liquid level detection device according to claim 1, wherein the liquid level detection device is contained. The secondary float is formed in a columnar shape,
The primary float connects the pair of end plate portions (61, 63) facing each of both end faces (71, 73) in the axial direction (AD) of the secondary float, and the pair of end plate portions. It has a connection part (66), The liquid level detection apparatus as described in any one of Claims 1-4 characterized by the above-mentioned. The fixed body has a cylindrical portion (23) that extends in a cylindrical shape and accommodates the switch mechanism,
The secondary float forms an insertion groove (75) through which the cylindrical portion is inserted by extending along the axial direction of the cylindrical portion, and the relative float in a direction intersecting the axial direction of the cylindrical portion. The liquid level detection device according to claim 1, wherein the cylindrical portion is separated from the insertion groove. The secondary float has a guide groove (76) extending along the direction of gravity,
The said primary float has a sliding part (69) which slides in the said guide groove and prescribes | regulates the range to which the said secondary float is displaced relatively. The liquid level detection apparatus described.

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