US2615102A

US2615102A - Bin level switch

Info

Publication number: US2615102A
Application number: US186663A
Authority: US
Inventors: Charles W Mcmath
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-09-25
Filing date: 1950-09-25
Publication date: 1952-10-21
Anticipated expiration: 1969-10-21

Description

Oct. 21, 1952 C. w. McM -1 2,615,102

BIN LEVEL SWITCH Filed Sept. 25, 1950 2 swears-4mm 1 CHARLES IL/ MfMnr/l IN V EN TOR.

ATTORNEY Oct. 21, 1952 c. w. MCMATH 2,615,102

BIN LEVEL SWITCH V. H 1 Filed Sept. 25, 195.0 2 SHEETS-SHEET 2 CHARLES W M9MATH INVENTOR.

AT T ORNE V Patented Oct. 21, 1952 UNITED STATES PATENT OFFICE f BIN LEVEL SWITCH Charles W. McMath, Fort Worth, Tex; I Application September 25, 1950, Serial No. 186,663

, 6 Claims. 1

This invention relates to switches and more particularly to pressure switches.

In many applications pressure responsive switches are employed to indicate or warn when a tank or bin is filled to a predetermined level. For example, such switches are employed to give warning when a gravel bin is filled with gravel to its capacity. The switches may also be employed to stop operation of loading equipment, which fills the bin with the gravel or other material, when the bin is filled to a certain level. Such switches should be adjustable in order that they may be adjusted to operate properly when attached to tanks or bins filled with different materials which exert different pressures on the switches. Moreover, the switches should be easily assembled and disassembled to facilitate maintenance and should be rugged in construction to withstand rough usage to which they are subjected.

Accordingly, it is an object of my invention to provide a new and improved. switch.

It is another object of my invention to provide a new and improved pressure responsive switch. It is another object of my invention to provide a new and improved pressure responsive switch for use with tanks or bins to indicate when the tank or bin is filled or emptied. I

It is still another object of my invention. to provide a new and improved pressure responsive switch having a diaphragm which is subjected to a very narrow range of movement.

Briefly stated, my new and improved pressure responsive switch comprises a base section adapted to be connected to a tank, bin or other receptacle r conduit and extend through an aperture in a wall thereof. A diaphragm is secured to the base section and has an inner surface subjected to the pressure exerted by the material or substance contained in the tank, bin or conduit.- In order to protect the diaphragm, a backing plate is provided which abuts the outer surface of the diaphragm. A mechanical linkage connects the backing plate to a micro-switch. An adjustable spring is operatively associated with the linkageto providea means selectively to vary the pressure to which the diaphragm must be subjected to actuate the micro-switch.

For abetter understanding of my-invention, r'eference may-be had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims. I

Figure. 1 is a sectional view of the switch shown in itsoperational environment;

ing flange l3, integral with and at one endof,

central portion II, is provided with a plurality of spaced apertures through which are adapted to extend screws M which engage in suitable tapped holes in wall [2. An annular resilient gasket 15 of rubber or other suitable material is interposed between flange l3 and wall l2. Gasket i5 is provided with a plurality of spaced apertures which register with the apertures in flange l3 and wall I 2.

An inwardly extending annular flange 16in tegral with and at the other end of central portion H is provided with an inner bevel surface I! and a plurality of spaced threaded apertures l8 between central portion H and beveled surface H. A diaphragm clamping ring I9 is alsoprovided with a beveled surface 20 which cooperates with beveled surface I! to secure a disc shaped diaphragm 2| to flange l6 of base section l0. Ring 19 is securedto flange It by screws 22 which extend through suitable apertures 23 in ring [9 and engage threaded apertures 18 of flange l6. Ring l9 and flange l6 cooperate to maintain the central portion of diaphragm 2| in a plane normally parallel to the outer surfacev 24 of flange I6. Diaphragm 2| may be made of a relatively stiff or slightly yielding material such as reinforced rubber, or a metal sheet of brass, copper, steel or other suitable material since very little diaphragm movement isneeded in normal operation of the device.

, The complementary beveled surfaces [1 and 20 of the flange l6 and ring, l9, respectively, are

effective to create the required uniform tension on the diaphragm 2| during its installation and to maintain such tension subsequent to installation.

A disc shaped cover plate 25 is secured to base section ID by means of screws 26 which extendthrough suitable apertures in plate 25 and engage in threaded holes 21 in base section 10. A supporting block28 having spaced legs 29and 30 is securedtoplate 25 by a screw 3| which ex tends through a suitable aperture in plate .25

and engaging in a threaded hole 32 in the upper end of block 28. A lever 33 is pivotally secured between legs 29 and 30 by means of a pin 34 which extends through registering apertures 35, 36 and 31 in legs 29, 30 and lever 33, respectively.

A ribbed backing plate 38 is secured to the free end of lever 33 by means of a screw 39 which extends through central apertures in backing plate 38 and a spacing sleeve 40 and engages in a threaded aperture 4| in lever 33. The upper end of screw 39 is spaced a very short distance from cover plate 25 to limit the movement of backing plate 38, and therefore of diaphragm 2 I, toward cover plate 25. Also secured to theinner surface of cover plate is a spring supporting block 42 which is secured to plate 25 by a screw 43. Block 42 is provided with a slot in which is rigidly secured, by soldering or any other conventional means, one end of a leaf spring 44. The free end of leaf spring 44 abuts and bears against lever 33 yieldingly to urge the free end of lever 33 away from cover plate 25. An adjusting screw 45 extends through a threaded aperture in cover plate 25 and bears against spring 44 to vary the force spring 44 exerts on lever 33. A look nut 46 is provided for screw 45 to lock it in a desired position.

Intermediate its ends, lever 33 is provided with a threaded aperture in which is engaged a screw 41 which is disposed to engage the push rod 48 of a conventional micro-switch 49 when lever 33 is moved pivotally toward plate 25. The microswitch 49 is secured in a housing comprising sections 50 and by means of pins 52 and 53- which extend through suitable apertures in sections 50, 5| and micro-switch 54. The housing sections 50 and 5| are secured to each other by means of bolts 55. Each section 50 and 5| is provided with a flange 56 provided with a pair of apertures through which extend screws 5| which engage in threaded holes 58 in cover plate 25'to secure the sections 5|! and 5| to plate 25. Cover plate 25 is also providedgwith an aperture 59 through which extend in telescoped relation the push rod 48 of micro-switch 43 and its sleeve 36. The housing sections 50 and 5| are provided with apertures 8! and 62 through one of which may extend the

conductors

63 and 64 which are connected to micro-switch 49.

Conductors

63 and 64 may be connected to any suitable electric circuit to control a warning or indicating device, a motor; or any other desired electricall controlled element In operation, the above described pressure responsive'switch is preferably secured to a vertical wall i2 of a tank, bin or conduit which wall may be vertical or any slope greater than the angle of repose of the material in the bin, or the like. When the bin or the like is filled to such av height with material that thematerial abuts and exerts a force on diaphragm 2|, the dia-' phragm 2| will yield inwardly toward plate 25 provided that the force exerted. by the material,

on diaphragm 2| overcomes the force exerted by spring 44 on lever33 as well as the force needed to flex diaphragm 2| and actuate micro-switch 49; t will be obvious that screw 45 will be employed to make the spring 44 exert an appropriate pressure on lever 33. When diaphragm 2| yields and moves, backing plate 38 will also move pivoting lever 33 toward plate 25. During this movement of lever 33, screw 4'! will, move push rod 48 to actuate micro-switch 42': to make or break an electric circuit. The pivotal movement of lever" 33 is limited since screw 39 will abut plate 25 after lever 33 has moved a predetermined distance. When the material in the bin falls to a level in which it no longer exerts sufiicient pressure on diaphragm 2|, the force exerted by spring 44 will move backing plate 38 to its original position illustrated in Figure 1. Diaphragm 2| will move back to its original position due to its resiliency.

It will be noted that diaphragm 2| does not extend, inwardly beyond flange 6 of base section l0 so that the material in the bin does not lie in the path of movement of the material to impede its movement and at the same time increase the abrasive wear of diaphragm 2|. Moreover, the. method of securing diaphragm 2| to base section, l0. obviates the need for bolt holes which would weaken the diaphragm 2|. The backing plate 38 protects diaphragm 2| from excessive force such as might result from the falling of rocks against diaphragm 2| in gravel bin installations.

The mechanical linkage is very simple, having only one pivot thus reducing friction losses to a minimum. In addition, the range of movement of diaphragm 2| is quite narrow permitting the use of a relatively taut diaphragm which eliminates sagging and the resulting tendency of, the diaphragm to trap or hold material in a hollow or fold caused by the sagging.

The arrangement and connection of parts of the above described pressure responsive switch Base facilitates installation and maintenance. section I 0 can be secured to wall l2 from the outside of the bin thus obviating the necessity of having access to the interior of the bin. The micro-switch 49 can be removed for inspection, repair or replacement without disturbing the other components of the system since screw 41 merely bears against push rod 48 of the switch. Should adjustment or repair of the mechanical linkage be necessary, cover plate 25 only need be removed since diaphragm 2| is not connected to backing plate 38 or any part of the mechanical linkage.

While I have described and illustrated a preferred embodiment of my invention, it will be obvious that various changes and modifications can be made without departing from my invention and I, therefore, aim in the appended claims to cover all such changes and modifications as !all within the true spirit and scope of myinvention.

What is claimed is l. A pressure responsive device comprising a hollow base section; a resilient diaphragm secured to said base section and closing of! one end of said base section; a cover plate secured to said base section and closing off the other end of said base section; a backing plate movably disposed in said base section and abutting said diaphragm; a lever. having one end pivotaily connected to' said cover, plate and the other end secured-tosaid'backing plate; means biasingsaid backing plate toward said diaphragm;- astop operatively associated with said backing plate for limiting movement of said backing plate toward said cover plate; and a switch mounted on said cover plate exteriorly of said base section, said cover platebeing provided with an aperture, said switch having an operatin member extending through said aperture into said base section, said operating member being operatively associated with said backing plate and responsive to movement of said backing plate toward said cover plate.

- 2. A pressure responsive device comprising a hollow base section; a resilient diaphragm se cured to said base section and closing on one end of said base section; a cover plate secured to said base section and closing oiT the other end of said base section; a backing plate movably disposed in said base section and abutting said diaphragm; a lever having one end pivotally connected to said cover plate and the other end secured to said backing plate; means biasing said backing plate toward said diaphragm; a stop operatively associated with said backing plate for limiting movement of said backing plate toward said cover plate; and a switch mounted on said cover plate exteriorly of said base section, said cover plate being provided with an aperture, said switch hav ing an operating member extendin through said aperture into said base section, said operating member being operatively associated with said lever and responsive to pivotal movement of said lever toward said cover plate.

3. A pressure responsive device comprising a hollow base section; a resilient diaphragm secured to said base section and closing on one end of said base section; a backing plate movably disposed in said base section and having one side abutting one side of said diaphragm, said backing plate substantially closing off said one end of said base section; a cover plate secured to said base section and closing off the other end of said hollow base section; a switch mounted on said cover plate exteriorly of said base section, said cover plate being provided with an aperture, said switch havin an operating member extending through said aperture into said base section; a lever pivoted at one ned to said cover plate and connected at its opposite end to the center of said backing plate and having engagement with said operating member for actuating said switch upon movement of said backing plate toward said cover plate, means biasing said backing plate toward said diaphragm and means for adjusting the tension on said biasing means.

4. A pressure responsive device comprising a hollow base section having an internally beveled flange on one end, a ring attached to the interior of said flange having a bevel corresponding to the bevel of said flange; a resilient diaphragm having its perimeter secured between the bevels of said ring and flange and closing off one end of said base section; a backing plate movably dis posed in said base section and having one side abutting one side of said diaphragm, said backing plate being substantially equal in diameter to the diameter of the effective area of said diaphragm; a cover plate secured to said base section and closing off the other end of said hollow base section; a switch mounted on said cover plate exteriorly of said base section, said cover plate being provided with an off-center aperture, said switch having an operating member extending through said aperture into said base section; a pivoted lever connecting said backing plate and said operating member for actuating said switch upon movement of said backing plate toward said cover plate; and means operatively associated with said lever for biasing said backing plate away from said cover plate.

5. In a pressure responsive device: a base section having a central aperture provided with an internally beveled flange, a ring having a bevel confronting the bevel of said flange, a resilient diaphragm secured at its perimeter between said ring and flange and closing off said central aperture at one end of said base section; a backing plate movably disposed in said base section relative to said central aperture and abutting said diaphragm, said backing plate having substantially the same radius as the effective area of said diaphragm; a cover plate secured to said base section and closing off said central aperture at the other end of said base section; a switch mounted on said cover plate exteriorly of said base section, said cover plate having an oil center aperture, said switch having an operating member extending through said aperture into said central aperture of said base section, a pivoted lever connecting said operating member and said backing plate for actuating said switch upon movement of said backing plate toward said cover plate and means for biasing said backing plate toward said diaphragm.

6. The device of claim 5, and a stop means operatively associated with said backing plate for limiting movement of said backing plate toward said cover member.

CHARLES W. MCMATH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 993,977 Frasier May 30, 1911 1,379,803 Covert May 31, 1921 2,441,480 Francis May 11, 1948 FOREIGN PATENTS Number Country Date 352,144 Great Britain July 9, 1931