JPH0339700Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a float guide shaft structure for a float-type liquid level sensor, in which the lowering stop position of the float can be appropriately selected without increasing the number of parts, and The present invention relates to a float guide shaft structure for a float type liquid level sensor that allows smooth vertical movement of a float.

<Prior art> For example, in the case of various liquid tanks used in automobiles, etc., a liquid level sensor is installed to turn on a remaining level warning light, etc. to prompt refilling before the tank becomes empty. There are things that are being done.

As a liquid level sensor, a so-called reed switch using a magnetically sensitive element is housed in a cylindrical float guide shaft, and a float equipped with a magnet for operating the reed switch is moved in the axial direction of the float guide shaft. A float-type liquid level sensor that can be freely fitted onto the outside is known. In this liquid level sensor, the float also moves up and down in response to the up and down movement of the liquid level in the tank, but when the float descends to a predetermined lowering stop position, the reed switch is activated by the magnet, It is necessary to continue issuing a warning signal at the location.

By the way, for example, in the case of a windshield fluid tank, the shape is different for each car model, so the remaining level warning position is also different, and it is necessary to prepare various liquid level sensors to change the lowering stop position of the float for each car model. Must be.

Therefore, a device in which the descending stop position of the float can be changed without changing the shape of the float guide shaft of the liquid level sensor is disclosed in Japanese Utility Model Application No. 61-46428. In this case, the lowering stop position of the float is changed by changing spacers of different heights, so it is necessary to prepare various types of spacers. Therefore, there is a problem that not only the number of parts increases but also the assembly becomes complicated.

Further, as disclosed in Japanese Utility Model Application No. 55-60632, a plurality of grooves are provided on the float guide shaft at intervals in the direction of movement of the float, for example, C
By engaging the ring in one of these grooves, the lowering stop position of the float can be appropriately selected. Therefore, since only one type of C-ring is required as a stopper for determining the lowering stop position of the float, the number of parts does not increase.

However, since multiple grooves are provided and one of them is used, if the float is tilted with respect to the axial direction when it moves up and down, the inner edge of the float will engage with the remaining groove. There is a risk that the float may get caught and malfunction.

<Problems to be solved by the invention> In view of the problems of the prior art, the main purpose of the present invention is to make it possible to appropriately select the lowering stop position of the float without increasing the number of parts, and to An object of the present invention is to provide a float guide shaft structure for a float type liquid level sensor that can operate smoothly.

<Means for Solving the Problems> According to the present invention, such an objective is to provide a float guide shaft that includes a float guide shaft that accommodates a magnetically sensitive element and a magnet that operates the magnetically sensitive element, and that at least part of the float guide shaft is provided with a magnet that operates the magnetically sensitive element. A float guide shaft structure of a float type liquid level sensor having an annular float fitted on the outer circumference so as to be movable in the axial direction, the float guide shaft having a predetermined shape on the outer circumference corresponding to the movement range of the float. A plurality of axial protrusions protruding with an angular pitch and a predetermined height, and a plurality of annular grooves provided at intervals in the axial direction between the protrusions on the outer peripheral surface of the float guide shaft. and a stopper member fixed to the float guide shaft by engaging with at least one of the annular grooves, and the protrusion restricts mutual contact between the annular inner peripheral edge of the float and the outer peripheral surface of the float guide shaft. This is achieved by providing a float guide shaft structure for a float type liquid level sensor, which is characterized in that the movement range of the float is defined by a stopper member.

<Operation> This prevents mutual contact between the annular inner circumferential edge of the float and the outer circumferential surface of the float guide shaft, so even if the float is tilted in the axial direction, the stopper will not engage. This prevents the inner edge of the float from getting caught in the remaining annular groove.
The float can move up and down smoothly. In addition, by engaging the stopper member with one of the plurality of annular grooves spaced apart in the axial direction, the position of the stopper member can be adjusted as appropriate, and the float can be floated with one type of float guide shaft. It becomes possible to select and change the lowering stop position of the

<Embodiments> The present invention will now be described in detail with reference to specific embodiments with reference to the accompanying drawings.

FIG. 1 is an overall partially cutaway view of a liquid level sensor to which the present invention is applied. A tank 1 for automobile window wash fluid is formed into a substantially box-like shape with a closed structure having, for example, a water inlet with a lid (not shown). As clearly shown in Figure 1,
A liquid level sensor 2 is installed at the bottom of the tank 1.
The tank 1 is erected from the bottom wall 1a toward the top of the tank 1. The liquid level sensor 2 has a housing 3 made of synthetic resin, and the housing 3 is fixed to the bottom wall 1a of the tank 1 via a packing 4. Note that the inside of the housing 3 is hollow;
Moreover, it is opened outward from the bottom wall 1a of the tank 1.

A cylindrical float guide shaft 5 extending upward is integrally formed in the upper part of the housing 3. The float guide shaft 5 is formed in a hollow shape so as to communicate with the outside of the tank 1 through the inside of the housing 3, and a so-called reed switch 6 using a magnetically sensitive element is installed at a predetermined position inside the float guide shaft 5. It is accommodated. Note that a connecting wire 6a of the reed switch 6 passes through the housing 3 and extends to the outside of the tank 1, and is electrically connected to, for example, a control unit, also not shown, via a connector, not shown. Then, a housing cover 1 is installed to cover the opening surface of the housing 3.
0 is attached by elastically engaging a hole 10a provided in the outer circumference with a claw 3a provided in the housing 3, so that the connecting wire 6a connects the intermediate portion between the housing 3 and the housing cover 10. It is clamped and fixed by. .

A hollow cylindrical float 7 is loosely fitted into the float guide shaft 5 so as to be movable in the axial direction, and an annular magnet 8 is fixed by molding to the inner circumference of the float 7 to operate the reed switch 6. has been done.

Further, the lower part of the float guide shaft 5 is gradually expanded in diameter toward the housing 3 to form an enlarged diameter stepped portion 5a that is larger in diameter than the outer diameter of the float 7. A cylindrical float cover 11 having an inner diameter substantially the same as the outer diameter of the enlarged diameter stepped portion 5a is fitted concentrically to surround the float guide shaft 5 and the float 7. A protrusion 12 is integrally provided at the free end of the float guide shaft 5, and a hole bored in the center of the top plate 11a of the float cover 11 is engaged with the protrusion 12. There is. Since the lower open end 11b of the float cover 11 reaches the outer circumferential surface of the enlarged diameter stepped portion 5a, the float 7
does not come off from the float guide shaft 5.

Incidentally, a plurality of slits 13 are bored in the top plate 11a of the float cover 11 in the circumferential direction, and grooves 13 are formed in the outer peripheral surface of the enlarged diameter stepped portion 5a along the axis.
4 is recessed, the inside and outside of the float cover 11 communicate with each other via the slit 13 and the groove 14. Therefore, the liquid level in the float cover 11 and the liquid level in the tank 1 are maintained at the same level.

FIG. 2 is an exploded perspective view showing the float guide shaft 5. As clearly shown in FIGS. 1 and 2, the outer peripheral surface of the float guide shaft 5 has, for example, six protrusions 16. They are integrally protruded along the axis at equal angular pitches. Further, a plurality of annular grooves 15 are provided at intervals in the axial direction on the outer circumferential surface between the protrusions 16 at the lower part of the float guide shaft 5 as engagement means.

An annular stopper member 17 is fixed to the float guide shaft 5 with its inner peripheral portion 18 engaged with one of the annular grooves 15. The stopper member 17 is
For example, it is made of synthetic resin and has an annular shape with approximately the same thickness as the width of the annular groove 15, but its outer diameter is larger than the diameter of the inner peripheral edge 19 at the lower end of the float 7, and its inner diameter is the same as the width of the annular groove 15. It is made slightly smaller than the outer diameter of the outer circumferential surface 20 of the guide shaft 5. Also,
As clearly shown in FIG. 2, the same number of grooves 21 corresponding to the protrusions 16 are cut into the inner peripheral portion 18. To attach this stopper member 17 to the float guide shaft 5, the groove 21 is aligned with the protrusion 16, and the float guide shaft 5 is inserted while elastically deforming the inner peripheral portion 18. Then, the deformation of the inner peripheral portion 18 engages with one of the annular grooves 15 and restores its original shape, whereby the stopper member 17 is fixed to the float guide shaft 5.

Therefore, when the float 7 is lowered, the lowering of the float 7 is stopped by the stopper member 17, and by changing the position of the stopper member 17, the lowering stop position of the float 7 can be appropriately determined.

In the liquid level sensor 2 configured in this way, the float 7 moves up and down in accordance with the up and down movement of the liquid level in the tank 1, and when the float 7 descends to the position of the reed switch 6, When the reed switch 6 is activated, the signal is input to a control unit (not shown) via the connection line 6a, and a remaining amount warning signal is output from the control unit.

By the way, since the capacities of tanks 1 of different shapes are different from each other, the lowering stop position of the float 7 is different from each other. However, according to the liquid level sensor 2 according to the present invention, the stopper member 17 is placed in each annular groove. The liquid level sensor 2 of the same shape can be used for various types of tanks 1 because it can be handled by engaging and fixing with any one of the tanks 15.

Furthermore, when the float 7 moves up and down, the float 7
The inner circumferential surface of the float guide shaft 5 comes into sliding contact with the protrusion 16, and the contact area becomes smaller than when it comes into sliding contact with the outer circumferential surface 20 of the float guide shaft 5, so the surface tension decreases and the outer circumferential surface of the float guide shaft 5 20
Therefore, the float 7 can move up and down smoothly.

By the way, if the float 7 is tilted with respect to the axial direction when descending, the inner peripheral edge 1 of the float 7
9 may engage with the annular groove 15 and the float 7 may not be able to descend. It is possible to prevent the peripheral edge 19 and the annular groove 15 from engaging with each other.

FIG. 3 is an explanatory diagram showing the relationship between the outer circumferential surface 20 and the protrusion 16 of the float guide shaft 5 and the inner circumferential edge 19 of the float 7. In the figure, the inner circumferential edge 19 of the float 7 is adjacent protrusions 1
6 are in contact with each other. Float guide shaft 5
The centers of curvature of the outer circumferential surface 20 and the inner circumferential edge 19 of the float 7 are respectively 01 and 02, the radius of curvature of the outer circumferential surface 20 of the float guide shaft 5 is r1, and the radius of curvature of the inner circumferential edge 19 of the float 7 is r2. A
is the contact point between the protrusion 16 and the inner circumferential edge 19 of the float 7, and the distance between 01 and A is a. Also, let the distance between 01 and 02 in the figure be x, and the distance between 01 and 02 is on the line connecting 01 and 02, and the 2
The shortest distance between the outer peripheral surface 20 of the float guide shaft 5 and the inner peripheral edge 19 of the float 7 on the equal dividing line L is δ
shall be. In addition, bisector L, line segment 01 and line segment 0
Let the angles formed with 2A be θ and α, respectively.

By the way, the inner peripheral edge 19 of the float 7 is in the annular groove 1.
In order to avoid engagement with 5, δ in FIG. 3 may be set to a positive value.

As shown well in Figure 3, δ=r2−(x+r1)…(1) There is a relationship between

Note that x=r2 cosα−a cosθ (2), and α=sin ⁻¹ (a sinθ/r2) (3).

Therefore, by substituting equation (3) into equation (2), and substituting equation (2) into equation (1), we get δ=r2−r1+a cosθ −r2 cos(sin ^-1 (a sinθ/r2 ) becomes.

Therefore, it is sufficient to determine θ that allows the protrusions 16 to be arranged at equal angular pitches according to each dimension of r1, r2, and a so that δ>0. For example, r
When 1 = 3.45 mm, r2 = 4.6 mm, and a = 3.7 mm, θ = 30° can be selected, and the protrusions 16 are provided at 6 locations.

In this embodiment, the protrusions 16 are arranged at six locations, but for example, according to the conditions of the above calculation formula, θ=
20° can also be selected, and in this case there will be 9 protrusions 16, so it goes without saying that the number of protrusions 16 is arbitrary, as long as each dimension relationship satisfies the above formula. . Further, the number of annular grooves 15 and their intervals can also be determined arbitrarily.

Further, in this embodiment, the liquid level sensor is used in the window washer liquid tank, but any tank using a float type liquid level sensor may be used, and it can be used in various types of tanks.

<Effects of the invention> As described above, according to the invention, by providing a plurality of annular grooves as engagement means on the float guide shaft of the liquid level sensor, the descending stop position of the float can be appropriately adjusted using only one type of stopper member. Therefore, it is possible to apply one type of liquid level sensor to tanks of different shapes without increasing the number of parts.

In addition, by suitably providing a plurality of protrusions along the axis at equal angular pitches on the float guide shaft, the inner circumference of the float slides only on the protrusions.
Not only can the inner circumferential edge of the float be prevented from engaging and getting caught in the annular groove, but also it is suitably prevented from sticking to the outer circumferential surface of the float guide shaft and causing malfunction, and the float can move smoothly. The effects are extremely large.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway view showing the entire float type liquid level sensor based on the present invention. FIG. 2 is an exploded perspective view showing an enlarged view of the float guide shaft of the float type liquid level sensor. FIG. 3 is an explanatory diagram showing the relationship between the float guide shaft, the protrusion, and the float. DESCRIPTION OF SYMBOLS 1...tank, 1a...bottom wall, 2...liquid level sensor, 3...housing, 3a...claw, 4...packet, 5...float guide shaft, 5a...diameter enlarged step, 6... ...Reed switch, 6a... Connection wire, 7
... Float, 8 ... Magnet, 10 ... Cover, 10a ... Hole, 11 ... Float cover, 1
1a...Top plate, 11b...Open end, 12...Protrusion, 13...Slit, 14...Groove, 15...Annular groove, 16...Protrusion, 17...Stopper member, 1
8...Inner peripheral part, 19...Inner peripheral edge, 20...Outer peripheral surface, 21...Groove.

Claims (1)

[Claims for Utility Model Registration] (1) A float guide shaft containing a magnetically sensitive element;
A float guide shaft structure for a float-type liquid level sensor, comprising: a magnet for actuating the magnetically sensitive element; and an annular float fitted around an outer peripheral portion of at least a portion of the float guide shaft so as to be movable in the axial direction. The float guide shaft includes a plurality of axial protrusions that protrude at a predetermined equal angular pitch and a predetermined height on an outer circumferential surface corresponding to a movement range of the float, and a plurality of axial protrusions on the outer circumferential surface. A plurality of engagement grooves are provided at intervals in the axial direction between the protrusions, and a stopper member is fixed to the float guide shaft by engaging with at least one of the engagement grooves. and the mutual contact between the annular inner circumferential edge of the float and the outer circumferential surface of the float guide shaft is regulated by the protrusion, and the movement range of the float is defined by the stopper member. The float guide shaft structure of the float type liquid level sensor is characterized by: (2) When the inner peripheral part of the float is in contact with two of the protrusions that are adjacent to each other, the radius of curvature of the outer peripheral surface of the float guide shaft is r1, the radius of curvature of the inner peripheral part of the float is r2, The distance from the center of the float guide shaft to the point of contact between the inner peripheral part of the float and the protrusion is a, the bisecting angle between the adjacent contact points at the center of the inner peripheral part of the float is α, When the bisecting angle between the contact points at the center of the float guide shaft is θ, the relational expression r2−r1+a cosθ−r2cos {sin ⁻¹ (a sinθ/r2)}>0 is satisfied. A float guide shaft structure for a float type liquid level sensor according to Claim 1 of the Utility Model Registration Claim, characterized in that the relative dimensions of each part are defined as follows.