US 3632925 A
A new and improved float responsive switch controls the level of a liquid in a tank. The vertical motion of the float as responding to the liquid level is changed to a rotary motion through use of magnetic responses, which rotary motion in turn activates selectively a microswitch controlling the level of the liquid.
Claims available in
Description (OCR text may contain errors)
United States Patent Inventor Katsqii Fujiwara No. 191, Nishitani, Hiraoka-cho, Kakogawa-shi, l-lyogo-ken, Japan App]. No. 843,591 Filed July 22, 1969 Patented Jan. 4, 1972 Priority Nov. 18, 1968 Japan 43/84298 FLOAT RESPONSIVE SWITCH UNIT 12 Claims, 9 Drawing Figs.
US. Cl 200/84 C, 73/317, 73/319, 77/322 int. Cl. 1101b 35/18 Field of Search ZOO/84.3, 84; 340/244 B; 73/3 i 7, 3l9, 322
 References Cited UNITED STATES PATENTS 2,356,652 8/1944 Connolly et al ZOO/84.3 UX 2,620,4l2 12/ i952 Ford ZOO/84.3 UX 2,666,823 l/l954 Wilson 200/843 UX 2,717,934 9/1955 Collins ZOO/84.3 UX 2,822,442 2/1958 Jones Z O/84.3 UX
Primary Examiner-David Smith, Jr. Attorney-McGlew and Toren ABSTRACT: A new and improved float responsive switch controls the level of a liquid in a tank. The vertical motion of the float as responding to the liquid level is changed to a rotary motion through use of magnetic responses, which rotary motion in turn activates selectively a microswitch controlling the level of the liquid.
PATENTED JAN 4:972
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, mm 5 0F 7 INVENTOR 9 su 3'1 F'US'IWRCQ ATTORNEYS FLOAT RESPONSIVE SWITCH UNIT The present invention is particularly adapted to be responsive to minor or slight changes in the level of a liquid in a container or tank.
It also is provided with a partition wall or insulating casing to maintain insulation of the mechanism from the influence of undesirable outside forces.
Float switches have been known in the prior art. The differences between the instant invention and those of the prior art lie basically in that instead of opening and closing either the liquid intake or outlet .valves directly by means of mechanical linkage operating in response to the float movement, the float movement activates electrical or magnetic control means. Thus, it is possible to achieve maximum operational response to the desired liquid level. The operation of the present invention, because it does not rely only on levers and mechanical links, can either be set to closely control minute changes in the liquid level or to respond only to major variations in the liquid level. As will be discussed in detail, the
size or shape of the mechanical cams used to induce switch operation can be adjusted to accomplish this result. The prior art devices did not have this flexibility and were either responsive only to major or very minor water level variations.
This eliminates the fear of inadvertent responses when this would not be desired.
Further, the rotary shaft is connected to the float, and the float is not directly connected to the activating mechanism. This means that repairs and maintenance are easier and that there is much less danger of repeated breakdowns.
A further advantage of the present invention is that the activating mechanism is not subjected to the direct pressure of the raising and lowering float or the liquid.
The switch mechanism of the present invention is also useful no matter what the dimension of the float is or what the length of the mechanical linkage is. It has an absence of supporting points and thus is both simple and efficient.
BRIEF EXPLANATION OF DRAWINGS Turning now to the drawings there is shown embodiments of the present invention.
FIG, 1 shows a longitudinal section of the float switch according to the invention in an installed state, the float being in the upper position and the circuit being closed.
FIG. 2 shows a section similar to FIG. 1, the float being in the lower position, the circuit being opened.
FIG. 3 shows the right side view of FIG. I, with a partial section taken along the line A-B of FIG. 1 and the switch cover removed.
FIG. 4 shows a partial section along the line C-D of FIG. 1.
FIG. 5 shows the left side view, wherein a partial section is taken along the line EF of FIG. 1.
FIG. 6 is a longitudinal section of a modification of the embodiment of FIG. 1.
FIG. 7 is a right side view of FIG. 6 with a partial section taken along the line G-H of FIG. 6 and the switch cover removed.
FIG. 8 is a plan view showing an application of the present invention.
FIG. 9 is a plan view showing a further application of the present invention.
The present invention relates to a float switch which is used to regulate a liquid level. The float switch according to the present invention will be explained with reference to liquid level control valves consisting of the combinations of the float switch with the electromagnetic valves.
In the prior art, valves which are controlled with the floats have been well known. However, the main valve of prior art liquid level control valves is opened and closed directly by means of a float, responsive to slight or small variations of the water level and consequently the control of liquid level is difficult. Further the prior art liquid level control valves have a lever mechanism with many supporting points which often get out of order. Repair or the part exchange is hard work because the main valve is mounted inside of the apparatus. Further, in prior art liquid level control valves, in order to open a main valve having a large diameter, it is necessary to make the size of float larger or the length of valves lever larger. Increasing the size of the float or the length of valves lever depending upon the pressure used makes the mechanism more complicated and larger, so that the handling as well as the maintenance becomes more difficult.
The present invention aims to avoid the above-mentioned difficulties by transferring the rotary motion imparted to the float-supporting shaft due to raising or sinking of the float out of the apparatus by means of a transmission mechanism utilizing magnetism to actuate a microswitch mounted outside of the apparatus connected to an electromagnetic valve. The rotating float support shaft reacting to raising or rotating action through a lever reacting to raising or sinking of the float surrounded by a casing. A first or outer magnetizable substance is attached to the shaft in such a manner that said substance rotates following said rotary shaft. Further a second or internal magnetic substance is provided in such a manner that said internal magnetic substance is opposite to said outer magnetizable substance but separated by a partition wall formed on a part of said casing in order to completely bar fluid from entering said casing. Thus there are provided two shafts, on each of which a magnetic substances is mounted and con nected in such a manner that due to mutual magnetic action'of both magnetic substances, the internal magnetic substances rotates, following up the outer magnetizable substance. With the rotary motion of said internal magnetic substance led out of the apparatus by means of a transmission mechanism constructed as above, the microswitch is actuated through a mechanism, such as a cam situated along the rotation axis of said magnetic substances, so that the electromagnetic valve is opened and closed.
Below, the present invention is explained according to the embodiments shown in FIGS. I to 5.
Numeral l is a float switch casing and 2 is a rotary shaft, which being rotatably inserted in casing l by means of a bushing 3. One end of said shaft 2 is provided with a concave notch, in which the convex part of the float mount 4 is inserted and both are connected with each other by means of a cotter pin 5. Further, on said float mount 4 downwardly depending lever arm 6 is secured with screw, with a float 7 connected to the lowermost extremity. As float 7 moves in up or down along line 7a, it will cause shaft 4 to rotate along line of arrow 4a about its longitudinal axis.
On the other end of said rotary shaft 2 is a flange part 8, having a square or otherwise shaped profile, which transmit the rotary motion imparted to shaft 2 by the raising or sinking of the float 7 to an outer or magnetizable substance 9 formed as a hollow cylinder. The outer magnetizable substance 9 is covered with a cylindrical shell 10 consisting of nonmagnetic material attached to shell 10. Numeral 11 is a cap-shaped protecting partition wall consisting of nonmagnetic material, disposed opposite to the outer magnetizable substance 9 defining a small clearance I2 between the magnetic substance 9 and cap 11.
Numeral 13 is a slide ring consisting of plastics such as Teflon, provided with a notch, in which the edge of the cylindrical nonmagnetic shell 10 is engaged in such a manner that said cylindrical shell slides smoothly while said clearance 12 is maintained.
In a hollow cylindrical chamber surrounded by said partition wall 11, in internal or second magnetic substance 14 corresponding to said outer magnetizable substance 9 is provided. This magnetic body I4 is completely shut out from the inside of the main casing l, in which the float 7 is contained, by said partition wall 11. Due to the rotation of the outer magnetizable substance 9 a magnetic reaction takes place, so that the internal magnetic substance 14 rotates following up the outer magnetizable substance 9. The internal magnetic substance 14 is held on shaft 15a by a bearing 15 while the shaft 15a, on which said magnetic substance is mounted, is connected with a shaft 18, on which a cam 17 is mounted, by means of a connecting piece 16. Numeral 19 is a microswitch, which by means of the cam 17 raises and lowers a switch lever 20 and actuates the on-off operation of the microswitch l9. Numeral 21, 22 are blocks on which the cam and the switch are placed, while 23 is a cover.
Because the cylindrical shell covering the outer magnetizable substance 9 on said magnetic clutch rotates, while its edge is inserted in the notch of said slide ring 13, there is always a small clearance 12 maintained between the inside of said outer magnetizable substance 9 and the partition wall 11. Thus the smooth rotation of said outer magnetizable substance 9 will endure for a long time because by means of said cylindrical shell 10 it is prohibited that dusts or iron chips attracted by the internal magnetic substance 14 would enter into said clearance 12.
The float switch according to the present invention is explained with the embodiment according to FIG. 8. The construction of FIG. 8 is such that valve 27 opens when the liquid level rises, and on the other hand, closes when the liquid level lowers.
Numeral 24 is a liquid inlet, while 25 is a tank, on the wall of which tank a float switch according to the present invention is attached and the float 7 is installed in said tank. Numeral 26 is a liquid outlet, while 27 is an electromagnetic valve, which is connected with the float switch. As the liquid coming in from the inlet 24 is accumulated in the tank 25 and the water level goes up, the float 7 also goes up due to its buoyancy. At this time, the rotary shaft 2 FIG. 1 is rotated by the lever 6 due to the buoyancy of the float, and at the same time, the outer magnetizable substance 9 and the cylindrical shell 10 connected with the connection piece of said rotary shaft 2 are rotated.
Consequently, the internal magnetic substance 14 reacting to the outer magnetizable substance 9 also rotates, following the latter due to the mutual magnetic combination action by both magnetic substances. This causes the selectively adjustable cam 17 also to rotate, wherein as shown in FIG. 3, the switch lever of the microswitch 19 is moved by means of said cam 17, and the electric circuit is closed. Thus, the electromagnetic valve 27 connected with said microswitch 19 in casing 23 is opened, wherein the liquid is led out of the apparatus through the liquid outlet 26. As the water level in the tank decreases, the float 7 also goes down. When said float 7 reaches a state shown in dotted lines in FIG. 5, the cam 17 rotates due to similar effect as above, and the switch lever 20 of the microswitch 19 takes a position as shown by dotted lines in FIG. 3, wherein the switch 19 is opened and the electromagnetic valve 27 is closed.
In short, the embodiment of FIG. 8 is best suited for exhausting condensed water for example, from steam machines because it is free from the influence of working pressure. In case of the embodiment shown in FIG. 9, the situation is simply reversed, whereby when the float goes down, the switch is closed, and when the float goes up the switch is opened, which can be used as so-called water supply equipment. In the cases shown in FIGS. 6 and 7, instead of the combination of cam mechanism and microswitch, the following mechanism is applied. Numeral 30 is a rotary body, while 31 is a shaft on which said rotary body is mounted and to which rotary motion is imparted just as described before with regard to shaft 18. A groove is provided on said rotary body 30 filled by a metal plate 32 consisting of well-conductirig material, such as copper, and secured with bolts and nuts. Numerals 33, 34 are terminal plates which are pressed against the rotary body 30 by springs 35, 36. As shown in FIGS. 6 and 7, the terminal plates 33, 34 are connected with each other through metal plate 32 so that both terminal rods 37, 38 are connected with each other, whereby the switch is closed.
When the float 7 goes down, the rotary body rotates as in case of the aforementioned embodiment, so that the metal plates 32 is disengaged from both terminal plates 33, 34, and the switch is opened. Therefore, it is necessary to make the rotary body 30 of a nonconductive material. Further, it is possible to construct this embodiment so that when the float 7 goes down, the switch is closed, or when the float 7 goes up the switch is opened, by simply changing the mounting of float lever 6.
While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.
What is claimed is:
l. A float responsive switch unit responsive to the position of a moving arm, comprising first magnetic means movable in response to movement of said arm, said first magnetic means having an inner portion connected to said arm and an outer portion following an arcuate path upon movement of said arm, second magnetic means magnetically coupled to said first magnetic means for moving in response to the shifting position of said first magnetic means, one of said magnetic means being permanently magnetized, regulator means responsive to said second magnetic means, a wall disposed between said first and second magnetic means, said wall having track means engaging said first magnetic means at said outer portion along the path of movement of said first magnetic means for guiding said first magnetic means and maintaining a clearance between said first magnetic means and said wall.
2. A mechanism as in claim 1, wherein said first magnetic means includes a first magnetic member and moving means holding said first magnetic member and responding to movement of said arm for moving said first magnetic member through a circular path, said track means following a circular path for engaging said first magnetic means near said first magnetic member.
3. A mechanism as in claim 1, wherein said first magnetic means includes a first magnetic member rotatable about an axis in response to movement of said arm, said first magnetic member being mounted to travel in a circular path about the axis in response to movement of said arm, said second magnetic means having a second magnetic member mounted for circular movement about the axis, one of said magnetic members being adapted to travel about a larger circular path than the other and surrounding the path of the other, said wall having a cap shaped section with a cylindrical portion extending coaxial to the axis and between the paths.
4. An apparatus as in claim 3, wherein said track means includes a circular track, and wherein the magnetic means having the magnetic member whose path surrounds the other path has a concave shape for receiving the cap-shaped section.
5. An apparatus as in claim 4, wherein said circular track includes a circular groove, said track engaging the periphery of said concave-shaped means with said groove.
6. An apparatus as in claim 3, wherein the path of said first magnetic member surrounds the path of said second magnetic member. 4
7. An apparatus as in claim 3, wherein said first magnetic member includes a magnetizable material and said second magnetic member includes a permanent magnet.
8. An apparatus as in claim 1, wherein said valve means are electromagnetic and said control means include electric switches for actuating said valve means.
9. An apparatus as in claim 3, wherein said first magnetic means and said wall form with said track means an enclosure for excluding particles from the space between said first magnetic means and said wall.
10. An apparatus comprising, a tank adapted for containing a flowable liquid, electromagnetic valve means to vary the level of the liquid in the tank, a float adapted to rest on the surface of the liquid and movable in a vertical plane as the liquid level varies, and a float switch mechanism to actuate said valve means, said switch mechanism including magnetic means reflecting changes in the liquid level in the tank, float responsive means connecting said magnetic means to said float, and valve control means connecting said magnetic means to said valve means, said magnetic means including a first magnetic material movable in response to the position of said float in the tank and a second magnetic material outside of said tank movable in response to the shifting position of said first magnetic material, valve control means actuated by said second magnetic material for controlling said valve means to stabilize the liquid level, said first magnetic material being concave and covering said second magnetic means, said tank having a wall including a hollow cylindrical cap disposed between said first and second magnetic materials, said cap including a cylindrical shell, track means on said wall engaging the outer periphery of said concave material to maintain a fixed clearance between said shell and said first magnetic substance.
11. The combination as defined in claim 10, wherein said float responsive means includes a shaft rotatable about a longitudinal axis perpendicular to the vertical plane of movement of said float, one end of said shaft extending outward of said housing and one end extending inward of said switch housing, a float mounting housing affixed to the outwardly extending end of said shaft, a lever fixedly connecting said float to said rotatable shaft in said float housing so that as said float raises or sinks said shaft rotates around its longitudinal axis, a flange on said shaft embedded in said first magnetic material and a bushing in said switch housing supporting said shaft for longitudinal rotation, said valve control means including a second rotatable shaft fixedly connected to said second magnetic material, a cam fixedly mounted to said second rotatable shaft, a microswitch mounted on said switch casing and a switch actuating lever in said microswitch engaging said cam, said track means including a slide ring and a notch in said slide ring, said flange engaging said notch.
12. A float-actuated switch mechanism comprising, support means, a rotary shaft rotatably held by said support means, said rotary shaft having mounted thereon a radial arm, said arm carrying a float, said rotary shaft having an end and a concave magnetizable member mounted on said end, said concave member having a circular periphery, said concave magnetizable member having an inner and an outer surface and being rotatable coaxially with said rotary shaft, a cylindrical portion of nonmagnetic material covering said member, a capshaped partition wall extending into the inner surface of said concave magnetizable member and forming an annular clearance therewith, said partition wall having a base portion extending radially outward therefrom, said base portion having a slide ring, said slide ring having an annular notched groove coaxial with said concave member for rotation therein of the periphery of said concave member, said concave member engaging said slide ring so as to form with said partition an enclosure for preventing entrance of particles therein, a magnet mounted for rotation on the other side of said partition wall in response to rotation of said magnetizable member, and switch means responsive to rotation of said magnet.