U.S. patent number 3,659,064 [Application Number 05/074,650] was granted by the patent office on 1972-04-25 for water surface switch.
This patent grant is currently assigned to C.D.M. Kabushiki Kaisha. Invention is credited to Mitsuo Inoue.
United States Patent |
3,659,064 |
Inoue |
April 25, 1972 |
WATER SURFACE SWITCH
Abstract
A float switch for opening and closing a circuit in response to
the level of a liquid comprising a permanent magnet which is
disposed loosely around a protection tube enclosing a lead switch,
the magnet being slidable along the tube to open or close the
switch contacts depending on the level of the liquid.
Inventors: |
Inoue; Mitsuo (Ibaragi,
JA) |
Assignee: |
C.D.M. Kabushiki Kaisha
(Kishiwada City, Osaka, JA)
|
Family
ID: |
25759687 |
Appl.
No.: |
05/074,650 |
Filed: |
September 23, 1970 |
Current U.S.
Class: |
200/84C; 73/308;
73/322.5 |
Current CPC
Class: |
H01H
36/02 (20130101); H01H 35/022 (20130101); G01F
23/32 (20130101); G01F 23/38 (20130101) |
Current International
Class: |
G01F
23/30 (20060101); H01H 36/00 (20060101); H01H
36/02 (20060101); H01H 35/02 (20060101); G01F
23/32 (20060101); G01F 23/38 (20060101); H01h
035/18 () |
Field of
Search: |
;200/82B,82C,61.52
;73/317,308,322.5,313 ;335/205 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith, Jr.; David
Claims
What I claim is:
1. A float switch for opening and closing the circuit in response
to the level of a liquid comprising a housing, a switch protection
tube mounted in said housing in spaced relation thereto, a lead
switch mounted in said protection tube, said switch having a pair
of contacts, a ring-shaped permanent magnet disposed loosely around
said protection tube for sliding movement therealong, means on said
protection tube for confining the axial movement of said magnet
along said tube, said magnet in one position of said float
resulting from a rise in the liquid level being radially aligned
with said contacts for closing the same and thus said circuit, and
in a second position of said float resulting from a drop in the
liquid level being displaced along said tube at a position
relatively remote from said contacts thereby permitting opening of
the same and thus said circuit.
2. The switch of claim 1 wherein the coefficient of friction
between said permanent magnet and said protection tube is such that
said permanent magnet slides along said tube only when said switch
reaches a predetermined angle of inclination relative to the liquid
level line.
Description
The present invention relates to a water surface switch which aims
at obtaining a floating control switch inexpensive yet reliable by
utilizing a lead switch instead of an expensive mercury switch
hitherto used.
The invention will be fully understood from the following
descriptions with reference to the annexed drawings in which:
FIG. 1 is a partial sectional view of a portion of a water surface
switch according to the invention, showing its position at a
lowered water level during drainage by a pump;
FIG. 2 is a partial sectional view of a portion of the water
surface switch showing its position at a raised water level.
Referring in more detail to the drawings, the invention comprises a
float 1 in which is mounted a ring-shaped permanent magnet 2
disposed loosely around a switch protection tube 9. The magnet is
retained around the tube by a stop member 5 mounted on the bottom
of the tube.
Mounted in tube 9 is a switch 7 which includes contacts 3 and 4.
The contacts are normally separated as shown in FIG. 1. A rubber or
resin coated electric cord 6 extends away from the switch for
electrical connection to the pump motor. The cord 6 is attached to
a weight 8 which controls or limits the bending of the cord. The
weight 8 is fixed vertically so that movement of the switch as the
water level rises or lowers is relative to the weight.
In the operation of the device, when the water surface is lowered
as illustrated in FIG. 1, the contacts 3 and 4 are kept open as the
permanent magnet 2 is moved down the tube to the position thereof
in FIG. 1 where it contacts the stopper 5. Consequently, no
electric current will flow through the motor and the draining pump
will be inoperative.
When the water level, and thus the float, rise to the position
illustrated in FIG. 2, the permanent magnet 2 will slide down along
the outer surface of the lead switch protection tube 9 until it
comes to and stops over the contacts 3 and 4. As a result, the
contacts 3 and 4 are closed by the magnetic force of the magnet 2,
thereby putting the switch circuit in a closed position, and
energizing the pump motor to initiate the draining operation.
As the pump keeps on draining water, the float moves from its FIG.
2 position to its FIG. 1 position. As the float moves downwardly
past an intermediate, horizontal position, the magnet 2 will slide
downwardly over the tube 9 until it contacts the stopper 5.
Consequently, the contacts 3 and 4 will be opened and the pump
motor stopped.
In order to make the permanent magnet 2 properly slide from its
position of FIG. 1 to that of FIG. 2, and vice-versa, the
coefficient of friction between the permanent magnet 2 and the lead
switch protection tube 9 preferably has a certain predetermined
value. At such value, the permanent magnet 2 slides into the
position of FIG. 2 from that of FIG. 1 only after it has reached a
certain upward inclination, and thus the pump will be made to start
its operation when a certain water level is reached. Similarly, the
permanent magnet 2, once having come to its position of FIG. 2,
will move into its position of FIG. 1 only when the lead switch
protection tube 9 has reached a certain level of downward
inclination in accordance with the decrease in the water level. Up
to that point, the pump will continue to be operated.
It will be apparent from the above description that the present
invention is characterized by its relatively low cost of
manufacture, the unfailing opening and closing actions of the
switch because of the utilization of a permanent magnet, and the
certain operation of the pump until the water level is lowered to
such an extent as to stop the pump motor.
* * * * *