JP2008292162A - Float switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a float switch that ensures positioning accuracy of an incorporated magnet by the shape of a magnetic float part and also has smooth and good following and response properties to variation of the level or the specific gravity of liquid. <P>SOLUTION: A float switch 41 comprises: a magnetic float 13 that incorporates a magnet 14 and moves up and down corresponding to variation of the level or the specific gravity of liquid; and a stem part 15 that guides up-and-down movement of this magnetic float 13 and incorporates a switch for detecting the approach of the magnet 14. The float switch 45 is characteristically provided with a plurality of recessed portions 43 on the face opposite the stem part 15 in the magnetic float 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a float switch that detects a change in a liquid surface position or a liquid specific gravity, and turns on / off a detection switch built in a stem when a magnetic float reaches a predetermined position, and is widely used particularly for industrial and household appliances. Relates to the float switch.

  FIG. 5 is a perspective view showing a float switch of a first conventional example, FIG. 6 is a longitudinal sectional view taken along line GG of the float switch of the first conventional example, and FIG. It is a horizontal sectional view in the HH line of the float switch of the prior art example. Details of the stem section were omitted. First, the float switch 11 according to the first conventional example will be outlined with reference to FIG. 5, FIG. 6, and FIG. The float switch 11 is composed of a magnetic float 13 incorporating a magnet 14 and a stem portion 15 incorporating a magnetic sensitive switch 25. The magnetic float 13 moves up and down along the guide surface 17 of the stem portion 15 in accordance with the vertical movement of the liquid surface 23, and a switching operation is performed by turning on and off the magnetic sensitive switch 25 built in the stem portion 15. A stopper 19 is provided at the lower end of the stem to prevent the magnetic float 13 from falling off.

  FIG. 8 is a first horizontal sectional view showing a float switch of a second conventional example, and FIG. 9 is a second horizontal sectional view showing a float switch of a second conventional example. With reference to FIG. 8 and FIG. 9, the float switch 26 according to the second conventional example disclosed in Patent Document 1 will be outlined. The overall configuration of the float switch of the second conventional example is similar to that of the first conventional example. Only a characteristic horizontal section is shown. As shown in FIG. 8, the float switch 26 is provided with a plurality of sticking prevention protrusions 31 on a guide surface 27 facing the magnetic float 13 of a stem portion 29 incorporating a magnetically sensitive switch. As shown in FIG. 9, a plurality of sticking prevention protrusions 39 may be provided on the inner peripheral surface 37 on the magnetic float 35 side facing the stem portion 15. With these sticking prevention protrusions 31 and 39, a stable clearance can be maintained between the magnetic float and the stem portion.

Japanese Patent Application Laid-Open No. 11-94631

  However, in the first conventional example, since the clearance between the guide surface 17 of the stem portion 15 and the magnetic float 13 is large, the magnetic float 13 is inclined when the magnetic float 13 moves up and down. For this reason, there exists a problem that the position accuracy of a liquid level detection is bad.

  Further, when the float switch 11 itself is tilted when used in a vehicle or the like, there is a problem that the friction resistance between the guide surface 17 and the magnetic float 13 is increased, and the followability / responsiveness of the magnetic float 13 is deteriorated.

  In the second conventional example, the plurality of sticking prevention protrusions 31 and 39 are provided on the surfaces of the stem parts 15 and 29 or the magnetic floats 13 and 35 facing each other. There is a problem that the molding die structure of 15, 29 or magnetic floats 13 and 35 becomes complicated and the cost of parts increases. In addition, due to the structure in which the float switch 11 is provided with a protrusion, it is necessary to increase the distance between the magnet 14 and the magnetic sensitive switch 25, and there is a problem that the clearance between the magnet and the magnetic sensitive switch cannot be reduced.

  According to the present invention, the shape of the magnetic float portion ensures the positioning accuracy of the built-in magnet, and can obtain a float switch having good followability and response smoothly with respect to fluctuations in the liquid level or liquid specific gravity. Another object of the present invention is to provide a structure with improved detection position accuracy and no malfunction by reducing the clearance between the magnet and the magnetically sensitive switch.

  The present invention has a magnet built-in, a magnetic float that moves up and down in response to a change in liquid level or a change in specific gravity of the liquid, and a stem that incorporates a switch that guides the vertical movement of the magnetic float and detects the approach of the magnet. A plurality of recesses are provided on a surface of the magnetic float facing the stem portion.

  Further, the present invention is characterized in that the concave portion has a groove shape along a buoyancy direction acting on the magnetic float.

  In the present invention, a part of the magnet is exposed in the recess.

  In the present invention, it is possible to secure the positioning accuracy of the magnet built in the magnetic float and increase the measurement accuracy. In addition, it is possible to obtain a float switch with smooth and good followability and response to fluctuations in the liquid level or liquid specific gravity, and the detection position accuracy is reduced by reducing the clearance between the magnet and the magnetically sensitive switch. As a result, the malfunction can be reduced. Furthermore, even if the clearance between the stem portion guide surface and the magnetic float is made smaller, not only the detection positional accuracy can be maintained, but also the molding cost of the stem portion or magnetic float is simplified, so that the cost of parts can be reduced. effective.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing a float switch according to an embodiment of the present invention, FIG. 2 is a horizontal sectional view taken along line AA of the float switch according to the embodiment of the present invention, and FIG. FIG. 4 is a horizontal sectional view taken along the line HH of the float switch according to the embodiment of the present invention, and a longitudinal sectional view taken along the line BB of FIG. 2. FIG. It is a horizontal sectional view in the HH line of the float switch, and is a longitudinal sectional view in the CC line of FIG.

  The float switch 41 is configured by combining a magnetic float 13 incorporating a magnet 14 and a stem portion 15 incorporating a magnetic sensitive switch 25. A harness 21 for the magnetically sensitive switch 25 is provided at the upper end of the stem portion 15.

  In the float switch 41, the magnetic float 13 moves up and down along the guide surface 17 of the stem portion 15 according to the vertical movement of the liquid surface and the change in the specific gravity of the liquid, and the magnet 14 has a magnetic sensitivity built in the stem portion 15. Switching operation is performed by turning on and off the switch 25. A stopper 19 is provided at the lower end of the stem portion 15 to prevent the magnetic float 13 from falling off.

  On the surface of the magnetic float 13 facing the guide surface 17 of the stem portion 15 (that is, the inner peripheral surface), four concave portions 43 are provided in the circumferential direction. The recess 43 has a groove shape or slit shape along the axial direction of the magnetic float 13 (that is, the buoyancy acting direction), and a part of the magnet 14 is exposed as shown in FIG. Yes. When the magnet 14 of the magnetic float 13 is insert-molded, the recess 43 can function as a portion that accommodates a mold for holding the magnet 14.

  That is, when the magnetic float 13 containing the magnet 14 is insert-molded, it is necessary to sandwich the magnet 14 with the upper and lower molds and fix the position. At this time, the arm portion that extends from the mold side and holds the magnet 14 can be configured to be the plurality of slit-shaped recesses 43 described above. The other inner peripheral surface of the magnetic float 13 is formed so as to coincide with the inner diameter of the ring-shaped magnet 14 so that the gap with the stem portion 15 can be easily reduced. Compared to the conventional example, the magnet 14 And the magnetic sensitive switch 25 have a small clearance.

  As described above, according to the float switch 41, the detection accuracy can be improved by reducing the clearance, and the manufacturing cost can be reduced. Therefore, there is an effect that the component cost can be greatly reduced. In particular, the magnetic float 13 can be manufactured by insert molding while holding the magnet 14 with a mold using the slit-shaped concave portion 43 which is a shape for followability and responsiveness, which will be described later. Can be improved.

  In addition, if a plurality of recesses 43 are formed in the circumferential direction in this way, frictional resistance, surface tension, and capillary action generated in the gap between the stem portion 15 and the magnetic float 13 can be suppressed. The followability and responsiveness are improved, and the detection accuracy can be increased.

  Although the embodiment has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there may be a design change or the like without departing from the gist of the present invention. For example, the detection of the flow and the switch may be not only liquid level detection but also liquid specific gravity detection.

The perspective view which shows the float switch of embodiment of this invention. The horizontal sectional view in the AA line of the float switch of embodiment of this invention. It is a horizontal sectional view in the HH line of the float switch of an embodiment of the invention, and is a longitudinal sectional view in the BB line of FIG. It is a horizontal sectional view in the HH line of the float switch of an embodiment of the invention, and is a longitudinal sectional view in the CC line of FIG. The perspective view which shows the float switch of the 1st prior art example. The longitudinal cross-sectional view in the GG line of the float switch of the 1st prior art example. The horizontal sectional view in the HH line of the float switch of the 1st conventional example. The 1st horizontal sectional view which shows the float switch of a 2nd prior art example. The 2nd horizontal sectional view showing the float switch of the 2nd conventional example.

Explanation of symbols

11, 26, 41 Float switch 13, 35 Magnetic float 14 Magnet 15, 29 Stem portion 17, 27 Guide surface 19 Stopper 21 Harness 23 Liquid surface 25 Magnetically sensitive switch 31, 39 Protrusion portion 33, 37 for preventing sticking Inner peripheral surface 43 Recess

Claims (3)

  A magnetic float that has a built-in magnet and moves up and down in response to a change in liquid level or a change in specific gravity of the liquid, and a stem that has a built-in switch that guides the vertical movement of the magnetic float and detects the approach of the magnet. A float switch having a plurality of recesses on a surface of the magnetic float facing the stem portion.   The float switch according to claim 1, wherein the concave portion has a groove shape along a buoyancy direction acting on the magnetic float.   The float switch according to claim 1 or 2, wherein a part of the magnet is exposed in the recess.

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