US3897172A

US3897172A - Motor control assembly for submersible sump pump

Info

Publication number: US3897172A
Application number: US347161A
Authority: US
Inventors: Malcolm S Hall
Original assignee: WAYNE HOME EQUIPMENT CO Inc
Current assignee: WAYNE/SCOTT FETZER Co A CORP OF
Priority date: 1973-04-02
Filing date: 1973-04-02
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29

Abstract

A control assembly for a sump pump including an electric motor and a motor case, the assembly comprising a housing closing the end of the motor case opposite the pump and having a switch compartment including a peripheral wall formed integrally therewith, and a closure member secured to the wall and closing the compartment. A float lever is pivotally coupled at its fulcrum to the chamber and has inner and outer ends which extend inwardly and outwardly of the compartment, respectively. A float assembly is coupled to the outer float lever end for pivoting the float lever between first and second positions in response to a fluid level, a first magnetic element is coupled to the inner float lever end and a second magnetic element is coupled to the closure member. The first and second magnetic elements magnetically engage when the float lever is adjacent its first position and are disengaged when the float lever is adjacent its second position. A switch is provided for energizing the motor including at least one operating lever and two simultaneously operable sets of switch contacts, the switch being mounted within the compartment with the switch lever in operative engagement with the float lever and being operated between conductive and non-conductive conditions in response to movement of the float lever. The switch operating levers are spring biased toward normally open positions thereby biasing the float lever toward the first position thereof. The force required to move the lever from its first to its second position is increased by the magnetic elements, and the force required to move the lever from its second to its first position is reduced when the lever approaches its first position by reason of the magnetic elements and the spring biasing means of the switches whereby actuation of the switch between conductive and non-conductive states is essentially instantaneous.

Description

United States Patent [191 Hall [ 1 MOTOR CONTROL ASSEMBLY FOR SUBMERSIBLE SUMP PUMP [75] Inventor: Malcolm S. Hall, Fort Wayne, Ind.

[73] Assignee: Wayne Home Equipment Co. Inc., Fort Wayne, Ind.

[22] Filed: Apr. 2, 1973 [21] Appl. No.: 347,161

[52] 11.8. Cl 417/40; 200/67 [51] Int. Cl. F04B 49/00 [58] Field of Search 417/40; 200/67 F, 84 C, 200/84 R; 73/317319, 305; 74/182 [56] References Cited UNITED STATES PATENTS 1,939,697 12/1933 Hunning ZOO/67 F 2,239,071 4/1941 Zeller 200/67 F 2,521,472 9/1950 McMahon 200/84 C 2,576,561 11/1951 Binford r r 200/34 C 2,577,165 12/1951 Thorshiem 200/84 C 2,680,167 6/1954 Shewmon 200/84 R 2,741,896 4/1956 Geiger 74/182 2,853,877 9/1958 Smith 73/305 2,927,174 3/1960 Walshin 417/40 3,005,068 10/1961 Pollak 417/40 3,050,605 8/1962 Pollak 200/84 R 3,442,219 5/1969 Fitzgerald 417/40 FORElGN PATENTS OR APPLlCATlONS 1,170,038 5/1964 Germany 200/84 C Primary Examiner--William L. Freeh July 29, 1975 electric motor and a motor case, the assembly comprising a housing closing the end of the motor case opposite the pump and having a switch compartment including a peripheral wall formed integrally therewith, and a closure member secured to the wall and closing the compartment. A float lever is pivotally coupled at its fulcrum to the chamber and has inner and outer ends which extend inwardly and outwardly of the compartment, respectively. A float assembly is coupled to the outer float lever end for pivoting the float lever between first and second positions in response to a fluid level, a first magnetic element is coupled to the inner float lever end and a second magnetic element is coupled to the closure member. The first and second magnetic elements magnetically engage when the float lever is adjacent its first position and are disengaged when the float lever is adjacent its second position. A switch is provided for energizing the motor including at least one operating lever and two simultaneously operable sets of switch contacts, the switch being mounted within the compartment with the switch lever in operative engagement with the float lever and being operated between conductive and nonconductive conditions in response to movement of the float lever. The switch operating levers are spring biased toward normally open positions thereby biasing the float lever toward the first position thereof. The force required to move the lever from its first to its second position is increased by the magnetic elements, and the force required to move the lever from its second to its first position is reduced when the lever approaches its first position by reason of the magnetic elements and the spring biasing means of the switches whereby actuation of the switch between conductive and non-conductive states is essentially instantaneous.

16 Claims, 6 Drawing Figures PATENTEDJULZQIQYS 8 17 2 sum 3 Down UP Force X Fluid T Level 316m Length Bouyunce Force MOTOR CONTROL ASSEMBLY FOR SUBMERSIBLE SUMP PUMP BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch assembly for use in a submersible sump pump, and in particular to such anassembly which utilizes a pair of magnetic elements and spring biasing means to effect essentially instantaneous operation of the motor control device between conductive and non-conductive states in response to predetermined fluid level changes.

2. Description of the Prior Art Motor control assemblies for use in submersible, electrically driven sump pumps are well known of which US. Pat. No. 2,927,174, issued to Walshin is typical. Such assemblies typically are provided with a fluid level responsive element, such as a float, which is operatively coupled to an electrical switch for turning the pump ON" and OFF. Typically, such assemblies are fluidtightly sealed units externally secured to the pump motor. In some instances, these motor control assemblies have been provided with magnetic elements and/or springs to improve the operation thereof, and, specifically, to insure that the control switches of the unit operate quickly and positively between conductive and non-conductive states.

SUMMARY OF THE INVENTION for use with a sump pump submersible in a fluid, the

pump including an electric motor having a motor case and means coupled to one end of the motor for pumping fluid. The motor control assembly comprises a motor end housing fixedly secured to and closing the end of the motor case opposite the pumping means, the end housing including a switch compartment having a peripheral wall formed integrally with the end housing and a compartment closure member secured to the wall and closing said compartment. A float lever is provided having a fulcrum pivotally coupled to the compartment and having inner and outer ends extending inwardly and outwardly of the compartment, respectively. Means are coupled to the outer float lever end for pivoting the float lever between first and second positions in response to a fluid level. A first magnetic element is coupled to the inner float lever end, and a second magnetic element is coupled to the closure member, the first and second magnetic elements being magnetically engaged when the float lever is adjacent its first position and being disengaged when the float lever is adjacent its second position. Switch means for electrically connecting and disconnecting the motor from a source of electrical energy is mounted within the compartment and includes at least one operating lever and two simul taneously operable sets of switch contacts. The switch means is positioned with its operating lever in operative engagement with the float lever inner end, the switch contacts being conductively coupled and separated in response to movement of the switch lever between its second and first positions, respectively. The switch lever is spring biased towards its first position thereby biasing the float lever towards its first position. The switch contacts are moved to their contacting, conductive position when the float lever has moved a distance sufficient to disengage the first and second magnetic elements, whereby the force requiredto move the lever from its first position to its second position is increased until said magnetic elements are separated and substantially reduced thereafter, and the force required to move the lever from its second to its first position is re duced when the lever approaches its first position by reason of the magnetic attraction between the first and second magnetic elements whereby actuation of the switch is essentially instantaneous and positive between both conductive and non-conductive states thereof. This eliminates short cycling" of the sump pump. That is, the magnetic elements prevent turning the pump ON and OFF in response to minor changes in the fluid level, ripples, and the like.

In a specific embodiment of the invention, the motor end casing and the peripheral wall of the switch compartment are molded of a single piece of a suitably moldable plastic, such as high density polyamide resin (nylon). Further, in a specific embodiment of the invention, the float control lever extends outwardly of the compartment through an opening in the compartment and a fluid-tight seal is provided between the float lever and the compartment by means of a resilient diaphragm or bellows type seal.

The motor control means includes a pair of singlepole, single throw switches, or in the alternative a double-pole, single throw switch, and the sump pump is driven by a single-phase electric motor whereby full electrical isolation is provided between the motor and a source of operating potential when the switch contacts have been opened. This feature of the invention also prevents damage to the sump pump motor caused by electrical surges in the power source coupled thereto.

Also in a specific embodiment of the invention, the compartment closure member includes an arm portion which extends outwardly of the motor casing, the arm portion providing a motion limiting abutment for a float used to operate the float lever.

In yet another specific embodiment, the motor control assembly includes a unique float member including two vertically spaced apart, buoyant bodies to enable operation of the control assembly between ON and OFF states in response to fluid level having larger level differentials.

It is therefore an object of the invention to provide an improved motor control assembly for use in a submersible, electrically driven sump pump.

It is another object of the invention to provide such an assembly having a switch compartment formed integrally with the motor end casing.

It is still another object of the invention to provide such an assembly which utilizes two sets of switch contacts to provide complete electrical isolation between an electric motor used to drive the sump pump and a source of operating potential when the sump pump has been automatically turned OFF.

It is yet another object of the invention to provide such an assembly which utilizes a pair of magnetic elements and a spring biasing means whereby the motor control assembly exhibits a unique hysteresis characteristic such that operation of the switch contacts between their conductive and non-conductive states and vice-versa is positive and essentially instantaneous.

It is another object of the invention to provide such an assembly having a unique float which enables operation of the assembly in response to wide fluid level differentials.

Another object of the invention is to provide such as assembly which is exceptionally simple in construction, inexpensive to manufacture and reliable in operation.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side plan view of the motor control assembly of the present invention shown affixed to an electrically driven sump pump with the switch compartment portion thereof being cut-away to show details of the motor control assembly;

FIG. 2 is an end, sectional view of the motor control assembly taken generally along section line 2-2 of FIG. 1;

FIG. 3 is a top, plan view of the motor control assembly shown with the closure member thereof removed;

FIG. 4 is an electrical schematic showing the connection of the sump pump electric motor to a source of operating potential; and

FIG. 5 and FIG. 6 are diagrams useful in explaining the operation of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown a motor control assembly indicated generally at 10 which is fixedly secured to sump pump 12 submersible in a fluid (not shown). Pump 12 includes electric motor 14 and fluid pumping means 16, such as a centrifugal pump, operatively coupled to end 18 thereof. Motor 14, which may be of the shaded pole type, includes casing 20 having upper end 22 to which assembly 10 is fixedly secured.

Assembly 10 comprises motor end housing 24 which includes a housing portion 26 having annular recess 28 therein. Resilient seal 30 is received within recess 28 and provides a fluid-tight seal between end housing 24 and casing end 22 when the latter is received within recess 28 as shown. End housing 24 is secured to casing 22 by means of elongated threaded fasteners 32. End casing 24 is further provided with bearing means 34 for rotatably supporting rotor shaft 36 of motor 14.

Formed integrally with end casing 24 is peripheral, upstanding wall 40 having a relatively wide, hollow wall portion 42 at one end thereof, wall 40 defining switch compartment 44 having recessed floor 46.

Closure member 48 is secured to distal edge 45 of wall 40 closing compartment 44. Gasket 50 is fitted be tween closure member 48 and wall 40 to provide a fluid-tight seal therebetween. Closure member 48 further includes arm portion 52 which extends horizontally outwardly of end housing 24. Arm portion 52 is of generally upwardly concave cross-section and includes circular opening 54 adjacent the end 56 thereof.

Formed through peripheral wall portion 42 and the contiguous portion of closure member 48 is cylindrical opening 60 of stepped-diameter. Elongated float lever 62 extends outwardly of compartment 44 through opening 60, lever 62 having inner end 64, an outer end 66 and fulcrum 68. Float lever 62 is pivotally coupled at its fulcrum 68 to peripheral wall 40 by means of suitable pivot pin 70 as shown.

Preferably, wall 42 is provided with a pair of laterally spaced-apart support portions as at 74. Each of portions 74 is provided with a nib as at 76 and closure member 48 is provided with a pair of laterally extending guides 78, fulcrum pin being clampingly engaged between guides 78 and nibs 76 and is slideably received through float lever 62. Float lever 62 further includes longitudinally extending rib 80 for reinforcement. End 66 of float lever 62 is provided with a circular enlargement 82 having therethrough a clearance wall 84.

Buoyant float 86 includes upper and lower cylindrical,

buoyant bodies

88, 90 which are fixedly coupled together in vertically, spaced-apart relationship via flexible float stem 92. A first, tapered float mounting pin 94 is secured to and extends vertically upwardly from float body 88 and a second tapered float mounting pin 96 is secured to and extends vertically downwardly from float body 90, as shown. Mounting pin 94 extends through clearance hole 84 and jam nut 98 is press-fitted thereon to thereby secure float 86 to float Iev er 62. Flexible strap 100, which may be made of any suitable flexible and resilient material such as rubber, synthetic rubber or plastic, is fitted to mounting pin 96 and secured to motor casing 12 via a suitable threaded fastener 102. Strap 100 is secured to float mounting pin 96 by means of second jam nut 104 press-fitted thereon. Strap 100 functions as a substantially frictionless guide for float 86, strap 100 maintaining float 86 in a vertical orientation. The double float body structure of the float 86 further effects a float having buoyancy characteristics similar to a very long float but wherein the maximum and minimum actuation forces generated thereby in response to rising and falling liquid levels occur at substantially separated liquid levels thereby to enhance operation of the motor control 10 by enabling operation thereof between ON and OFF conditions at greater fluid level differentials. Referring to FIG. 6, there is shown graphically the buoyancy force of float 86 versus the level of the fluid in which it is located. In FIG. 6, it is assumed that the float 86 remains stationary. Assuming that the buoyant forces required to operate control assembly 10 between ON and OFF conditions occurs at points X and Y, it will be seen that these points are separated relative to fluid level in direct proportion to the length of stem 92.

Coupled to float lever end 64 is a small, cylindrical magnet 110. Float lever end 64 has therethrough a small clearance hole (not shown) and magnet is coupled thereto by means such as a rivet 112. Preferably, a small wafer spring 114 is fitted between magnet 110 and float lever end 64, spring 114 functioning as a retainer and a spacer. Further, rivet 112 is preferably loosely fitted through the clearance hole (not shown) in float lever end 64 whereby magnet 110 is capable of swiveling movement.

A second magnetic element 116, a rectangular plate of non-magnetized magnetic material, is secured to closure member 48 by means of stem formed integrally with closure member 48. Preferably, stem 120 includes an enlarged base portion 122 having a tapered surface 124 and element 116 is secured thereto by means of jam nut 126 such that magnetic element 116 is disposed at a small angle as shown. This enhances the mechanical engagement of element 116 with magnetic element 110 by orienting the cooperating surfaces of the magnetic elements 110, 116 in mutual parallelism,

orthogonal to the relative movement therebetween at the time of contact.

. are rendered electrically contacting when operating levers 134 are depressed downwardly (as viewed in FIG.

1).

Switches

130, 132 are positioned such that their operating levers 134 are in abutting contact with a protuberance 150 on float lever 62 whereby pivotal move-'' ment of operating lever 62 from the position thereof illustrated in FIG. 1 to a second position assumed when float 86 is moved upwardly as shown in dashed lines in FIG 1 effects actuation of

switches

130, 132 from their non-conductive to their conductive states. The electrical connections to motor 14 are not illustrated in FIGS. 1 through 3. However, it will be apparent that switches 130,132 in conjunctionwith an electrical cord 148 provide a means for electrically connecting the motor 14 to a source of operating potential (not shown). Cord 148 is fitted through a cord opening 149 in closure member 48 and a fluid-tight seal therebetween is provided by a resilient grommet 151. Motor 14 is a singlephase. shaded pole motor whereby switches 130, 132 effect complete electrical separation between the motor 14 and a source of operating potential (not shown) when switches 130, 132 are in their normally open position.

It will further be observed that the operating levers 134, by reason of their being spring biased upwardly, also bias float lever end 64 upwardly.

Cylindrical opening 60 is provided with annular recess 152 and float lever 62 has therein annular recess 154 disposed concentrically of annular recess 152. Resilient, flexible diaphragm or bellows type seal 156 has inner and outer

annular portions

158, 160 sealingly received in

recesses

154, 152, respectively, to thereby fluid-tightly seal opening 60.

Referring now to FIG. 5, there is shown a force versus motion chart of themotor control assembly 10. The motion indicated in FIG. 5 is the movement of float lever end 64 and the force is that exerted by float 86. Initially, at point A, the fluid (not shown) surrounding float 86 is at a low level and float 86 is at its lowest position. As the fluid begins to rise, the float initially remains at rest. When sufficient buoyancy is generated to lift the weight of float 86, float 86 rises and all slack in the motor control assembly is first taken up. However, further movement of the float lever end 64 in a downward direction is prevented by the magnetic engagement of magnetic elements 110, 116. As the fluid continues to rise, the buoyant force on float 86 and therefore the downward force against float lever end 64 increases without producing any further movement of the float lever end 64. When the buoyant force generated by the float 86 exceeds the magnetic engaging force between magnetic elements 110, 116 and the spring biasing force generatedby the spring biasing means (not shown) inside

switches

130, 132, magnetic elements 110, 116 are forcibly separated. This occurs at point C. As soon as magnetic elements 110, 116 separate, the magnetic engaging force therebetween is substantially reduced. Correspondingly, the buoyant force generated by float 86 now substantially exceeds the spring biasing force against float lever end 64 generated by

switches

130, 132. As a result, float 86 moves rapidly upwardly and float lever end 64 moves rapidly downwardly against switch actuating levers 134. If the

switches

130, 132 are positioned such that they operate from their non-conductive, noncontacting conditions to their closed, conducting conditions at point D, it will be seen that the switches are operated from their nonconductive to their conductive states virtually instantaneously once the magnetic engagement of magnetic elements 110, 116 is broken. Float 86 continues to move upwardly by reason of thebuoyant force thereagainst until it mechanically abuts arm portion 52 at which point further increases in the buoyant force thereagainst produce no further movement in float lever 62. This occurs between points E and F.

When the fluid lever surrounding the sump pump 10 begins to decrease, float 86 does not move until the buoyancy thereof is insufficient to hold same in abutting contact with arm portion 52. At point E, the buoyancy force is again equal to the weight (downward force) and spring biasing force exerted by

switches

130, 132. Any further drop in the fluid level surrounding sump pump 12 results in downward movement of the float 86 with corresponding upward movement of the float lever end 64. This movement continues from point E to point G, at which point switches 130, 132 still have not been operated from their closed to their opened positions by reason of the positioning thereof with respect to float lever end 64. However, at point G, magnetic elements 110, 116 move closely together. Correspondingly, magnetic attraction or magnetic field interaction therebetween becomes significantly stronger, and magnetic elements 110, 116 are drawn closer together. This attracting force is additive to the weight of float 86 and the spring biasing force of switches 130, I32. Correspondingly, the magnetic attracting force causes float lever end 64 to move upwardly. As this occurs, the magnetic elements 110, 116 move closer together and their magnetic attractive force increases. Correspondingly, float lever end 64 is caused to move abruptly upwardly until magnetic elements 110, 116 come into physical contact. This occurs at point H in FIG. 5. It will be observed that

switches

130, 132, by reason of their positioning relative to float lever end 64, are caused to operate from their conductive to their non-conductive states at point J. Correspondingly, it will be observed that the operation of

switches

130, 132 from their conductive to their non-conductive states is also essentially instantaneous. To complete the operating cycle of the motor control assembly 10, further lowering of the fluid level allows float 86 to continue to drop until it reaches the limits of its mechanical movement. This occurs between points H and I in FIG. 5. Further lowering of the fluid level does not result in any further lowering of the float 86 and, correspondingly, an increase in the downward force of the float 86 only causes a return to point A in FIG. 5.

From the above description, it will be observed that the magnetic elements 110, 116 effect a unique hysteresis curve for the operation of

switches

130, 132. Preferably, motor end casing 26 and wall 40 are molded in a single piece from a paramagnetic material such as a high density, polyamide (nylon). Similarly, closure member 48 is molded of the same material. A paramagnetic material is preferred for the motor end casing 24 and closure member 48 so that these elements do not effect the magnetic attraction between magnetic elements 110, 116. The motor control assembly of the present invention is further seen to provide improved operating characteristics by reason of the unique hysteresis loop thereof which is effected by the magnetic elements 110, 116. Further, because the motor control assembly utilizes two sets of switch contacts, it provides for complete electrical isolation between the electric motor 14 used to drive the sump pump 12 and a source of operating potential whenever the sump pump 12 has been turned OFF". This prevents damage to the motor 14 which might otherwise result from power surges in the electrical lines connected thereto. The entire assembly is simple in construction and economical to produce. The entire electrical control is contained within a fluid-tightly sealed compartment and the compartment is provided as an integral part of the motor end casing 24. All parts of the motor control assembly with the exception of the magnetic elements,

electrical switches

130, 132 and seals can be molded from a suitable plastic material.

Also, from the above description, it will be observed that the motor control assembly includes an electrical switch means comprising the switch 130, a mechanical means comprising the float lever 62, a float means comprising the float 86 and the mechanical means or float lever 62, and magnetic means comprising the magnets 110 and 116.

Further, the unique float 86 used with the motor control assembly 10, by reason of its vertically, spacedapart

buoyant bodies

88, 90 and the weight to volume ratios thereof cooperate with the aforesaid unique hysteresis curve, as provided by the magnetic elements 110 and 116 to provide a motor control assembly which can be operated at widely separated fluid levels. While there have been described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.

What is claimed is:

1. In combination with a sump pump submersible in a fluid, the pump including an electric motor having a motor casing and means coupled to one end of said motor for pumping fluid, a fluid level responsive motor control assembly comprising a motor end housing fixedly secured to and closing the end of said motor casing opposite said pumping means, a switch compartment including a peripheral wall formed integrally with said end housing and a compartment closure member secured to said wall and sealably closing said compartment, a float lever having a fulcrum pivotally coupled to said compartment adjacent said peripheral wall and having inner and outer ends extending inwardly and outwardly of said compartment, respectively, means coupled to said outer float lever end for pivoting said float lever between first and second positions in response to a fluid level, a first magnetic element coupled to said inner float lever end, a second magnetic element coupled to said closure member in vertical registry with said first magnetic element, said first and second magnetic elements being magnetically and physically engaged when said float member is adjacent said first position thereof and being disengaged when said float lever is adjacent said second position thereof, switch means for electrically connecting and disconnecting said motor to and from a source of electrical energy, said switch means having at least one operating lever and two simultaneously operable sets of switch contacts and being operative between conductive and non-conductive conditions in response to movement of said switch lever, said switch means being fixedly mounted in said compartment with said switch lever in operative engagement with said inner end, said switch means being normally spring biased to one of said conductive and non-conductive conditions, said switch means being operable to one of said con-ductive and non-conductive conditions when said float lever has moved a distance from said first to said second positions thereof just sufficient to physically disengage said first and second magnetic elements, and to the other of said conductive and non-conductive conditions in synchronism with engagement of said first and second magnetic elements, the force required to move said lever from said first position to said second position being increased by said physically engaged magnetic elements until said magnetic elements are separated whereby said lever is maintained in said first position by magnetic field interaction of said magnetic elements and the magnetic force developed thereby until said fluid level has changed sufficiently to produce a change in the buoyant force of said means which exceeds said magnetic force.

2. The assembly of claim 1 wherein said compartment has a cylindrical opening therethrough, said lever extending outwardly of said compartment through said opening, said lever having a cylindrical enlargement thereon adjacent its fulcrum, said enlargement having a diameter smaller than the diameter of said opening and disposed therein, first and second annular grooves in the cylindrical surfaces of said opening and said enlargement, respectively, a resilient, annular, diaphram seal having inner and outer annular portions, said first and second annular portions being received in said first and second annular grooves, respectively, thereby fluid-tightly sealing said compartment.

3. The assembly of claim 1 wherein said switch means includes a pair of normally open, single-pole, single throw switches, each of said switches including a said operating lever, said float lever having a protuberance thereon disposed in abutting engagement with said operating lever.

4. The assembly of claim 1 wherein said closure member includes an arm portion extending horizontally outwardly of said end housing, said float lever pivoting means including a fluid float coupled to said lever outer end, said float abutting said arm portion when said float lever is in said second position thereof.

5. The assembly of claim 1 wherein said float lever arm is elongated and of generally rectangular crosssection, said float lever arm including a reinforcing rib formed integrally therewith and extending longitudinally thereof, said first magnetic element being a cylindrical magnet coupled to the upper surface of said float lever arm, a coupling pin fixedly secured to said first magnetic element and through an over-sized clearance hole in said float lever arm first end, the distal end of said coupling pin being enlarged to a diameter larger than said clearance hole, said second magnetic element being a generally flat plate of non-magnetized magnetic material fixedly secured to the under surface of said closure member in vertical registry with said first magnetic element, said float lever further including a fulcrum pin extending horizontally therethrough in a direction perpendicular to the longitudinal dimension thereof, said fulcrum pin being clampingly received between said peripheral wall and said closure member.

6. The assembly of claim 1 wherein said float lever pivoting means includes a buoyant float, said float in cludingupper and lower buoyant float bodies and means for coupling said bodies together in fixed vertically spaced-apart relationship.

7. The combination of claim 6 wherein said float is pivotally coupled to said float lever outer end and further including a float guide including a resilient, flexible strap coupled at one end thereof to said lower bouyant body and at the other end thereof to said motor.

8. The assembly of claim 1 wherein said end housing, peripheral wall, closure member, and float lever are made of a nonmagnetic material.

9. The assembly of claim 6 wherein said end housing, peripheral wall, closure member and float lever are molded of a high density, thermoplastic polyamide.

10. In combination with a sump pump submersible in a fluid, the sump pump including an electric motor having a motor casing and means coupled to one end of said motor for pumping fluid, a fluid level responsive motor control assembly which comprises:

electrical switch means being electrically and mechanically connected to said motor; float means comprising a float and mechanical means operably connected thereto for laterally positioning said float in relation to said fluid, said mechanical means including means for permitting vertical movement of said float in response to the buoyancy thereof and changes in said fluid level, and means for transmitting said vertical movement to said switch means thereby to actuate said switch means to conducting and non-conducting conditions; and

magnetic means, including a first magnetic element being operably connected to said mechanical means and a second magnetic element being operably connected to said motor, for providing a restraining force to prevent movement of said mechanical means thereby preventing movement of said float with a change in said fluid level, and preventing actuation of said switch means from one of said conditions to the other of said conditions until the change in said fluid level and the buoyancy of said float generate a force greater than and opposite in direction to said restraining force, said mechanical means including a float lever being horizontally disposed above said float, having one end thereof connected to the upper end of said float, being pivotally mounted to said motor about a horizontal axis transverse to the longitudinal axis of said float lever and distal from said one end thereof to permit said vertical movement of said float, and engaging said switch means distal from said pivotal mounting to provide said actuating of said switch means;

said connection of said first magnetic element to said mechanical means comprising the connection of said first magnetic element to said float lever at a position remote from said pivotal mounting and disposed to enter into magnetic field interaction with said second magnetic element when said fluid is at a first level and said switch means is in one of said conditions.

11. The sump pump of claim 10 in which said motor includes an upper motor housing having an upstanding wall on the upper surface thereof that defines a switch compartment;

said switch compartment includes an opening adjacent to said one end of said float; said pivotal connection of said float lever is intermediate of said one end and the distal end of said float lever and is in said switch compartment proximal to said opening, whereby said one end of said float lever and a first portion thereof adjacent thereto is disposed outside said switch compartment and said distal end of said float lever and a second portion thereof adjacent thereto is disposed inside of said switch compartment; and

said first and second magnetic elements are located inside said switch compartment, include cooperating surfaces adjacent to each other, and are positioned with respect to said pivotal mounting and said distal end to provide contacting of said cooperating surfaces by substantially orthogonal movement of one of said surfaces relative to the other of said surfaces and thereby to achieve maximum magnetic field interaction.

l2. The sump pump of claim 10 in which said connection of said float lever to said float comprises a swivable connection; and

a flexible strap being substantially horizontally disposed, having one end thereof connected to the lower end of said float, and having the other end thereof connected to said motor.

13. The sump pump of claim 10 in which said magnetic field interaction includes physical contact of said magnetic elements.

14. The sump pump of claim 13 in which said magnetic elements each include a cooperating surface, said physical contact is therebetween, and said cooperating surfaces are disposed to provide substantially orthogonal relative movement of said cooperating surfaces when said cooperating surfaces enter into said physical contact.

15. The sump pump of claim 14 in which said operable connection of one of said magnetic elements comprises swivel mounting thereof, whereby conforming contact of said cooperating surfaces is assured.

16. A sump pump of the type which includes a submersible pump, an electric motor being operably connected to said pump, an electrical switch being electrically and mechanically connected to said motor, and float .means for submersion into a fluid, said float means being operably connected to said switch for actuation thereof to conducting and non-conducting conditions in response to changes in the level of said fluid, the improvement which comprises:

said float means includes first and second vertically spaced floats, having a weight to volume ratio such that said float means will float with one of said floats partially submerged in said fluid, for actuation of said switch to one of said conditions when said fluid is at a first level wherein said one float is partially submerged; and

magnetic means, including a first magnetic element being operably connected to said float means and a second magnetic element being operably connected to said motor, for providing a restraining force to said float means thereby to prevent movement of said float means and actuation of said switch to the other of said conditions by said float means until the level of said fluid changes and the other of said floats is partially submerged.

Claims

1. In combination with a sump pump submersible in a fluid, the pump including an electric motor having a motor casing and means coupled to one end of said motor for pumping fluid, a fluid level responsive motor control assembly comprising a motor end housing fixedly secured to and closing the end of said motor casing opposite said pumping means, a switch compartment including a peripheral wall formed integrally with said end housing and a compartment closure member secured to said wall and sealably closing said compartment, a float lever having a fulcrum pivotally coupled to said compartment adjacent said peripheral wall and having inner and outer ends extending inwardly and outwardly of said compartment, respectively, means coupled to said outer float lever end for pivoting said float lever between first and second positions in response to a fluid level, a first magnetic element coupled to said inner float lever end, a second magnetic element coupled to said closure member in vertical registry with said first magnetic element, said first and second magnetic elements being magnetically and physically engaged when said float member is adjacent said first position thereof and being disengaged when said float lever is adjacent said second position thereof, switch means for electrically connecting and disconnecting said motor to and from a source of electrical energy, said switch means having at least one operating lever and two simultaneously operable sets of switch contacts and being operative between conductive and non-conductive conditions in response to movement of said switch lever, said switch means being fixedly mounted in said compartment with said switch lever in operative engagement with said inner end, said switch means being normally spring biased to one of said conductive and nonconductive conditions, said switch means being operable to one of said con-ductive and non-conductive conditions when said float lever has moved a distance from said first to said second positions thereof just sufficient to physically disengage said first and second magnetic elements, and to the other of said conductive and non-conductive conditions in synchronism with engagement of said first and second magnetic elements, the force required to move said lever from said first position to said second position being increased by said physically engaged magnetic elements until said magnetic elements are separated whereby said lever is maintained in said first position by magnetic field interaction of said Magnetic elements and the magnetic force developed thereby until said fluid level has changed sufficiently to produce a change in the buoyant force of said means which exceeds said magnetic force.

5. The assembly of claim 1 wherein said float lever arm is elongated and of generally rectangular cross-section, said float lever arm including a reinforcing rib formed integrally therewith and extending longitudinally thereof, said first magnetic element being a cylindrical magnet coupled to the upper surface of said float lever arm, a coupling pin fixedly secured to said first magnetic element and through an over-sized clearance hole in said float lever arm first end, the distal end of said coupling pin being enlarged to a diameter larger than said clearance hole, said second magnetic element being a generally flat plate of non-magnetized magnetic material fixedly secured to the under surface of said closure member in vertical registry with said first magnetic element, said float lever further including a fulcrum pin extending horizontally therethrough in a direction perpendicular to the longitudinal dimension thereof, said fulcrum pin being clampingly received between said peripheral wall and said closure member.

6. The assembly of claim 1 wherein said float lever pivoting means includes a buoyant float, said float including upper and lower buoyant float bodies and means for coupling said bodies together in fixed vertically spaced-apart relationship.

10. In combination with a sump pump submersible in a fluid, the sump pump including an electric motor having a motor casing and means coupled to one end of said motor for pumping fluid, a fluid level responsive motor control assembly which comprises: electrical switch means being electrically and mechanically connected to said motor; float means comprising a float and mechanical means operably connected thereto for laterally positioning said float in relation to said fluid, said mechanical means including means for permitting vertical movement of said float in response to the buoyancy thereof and changes in said fluid level, and means for transmitting said vertical movement to sAid switch means thereby to actuate said switch means to conducting and non-conducting conditions; and magnetic means, including a first magnetic element being operably connected to said mechanical means and a second magnetic element being operably connected to said motor, for providing a restraining force to prevent movement of said mechanical means thereby preventing movement of said float with a change in said fluid level, and preventing actuation of said switch means from one of said conditions to the other of said conditions until the change in said fluid level and the buoyancy of said float generate a force greater than and opposite in direction to said restraining force, said mechanical means including a float lever being horizontally disposed above said float, having one end thereof connected to the upper end of said float, being pivotally mounted to said motor about a horizontal axis transverse to the longitudinal axis of said float lever and distal from said one end thereof to permit said vertical movement of said float, and engaging said switch means distal from said pivotal mounting to provide said actuating of said switch means; said connection of said first magnetic element to said mechanical means comprising the connection of said first magnetic element to said float lever at a position remote from said pivotal mounting and disposed to enter into magnetic field interaction with said second magnetic element when said fluid is at a first level and said switch means is in one of said conditions.

11. The sump pump of claim 10 in which said motor includes an upper motor housing having an upstanding wall on the upper surface thereof that defines a switch compartment; said switch compartment includes an opening adjacent to said one end of said float; said pivotal connection of said float lever is intermediate of said one end and the distal end of said float lever and is in said switch compartment proximal to said opening, whereby said one end of said float lever and a first portion thereof adjacent thereto is disposed outside said switch compartment and said distal end of said float lever and a second portion thereof adjacent thereto is disposed inside of said switch compartment; and said first and second magnetic elements are located inside said switch compartment, include cooperating surfaces adjacent to each other, and are positioned with respect to said pivotal mounting and said distal end to provide contacting of said cooperating surfaces by substantially orthogonal movement of one of said surfaces relative to the other of said surfaces and thereby to achieve maximum magnetic field interaction.

12. The sump pump of claim 10 in which said connection of said float lever to said float comprises a swivable connection; and a flexible strap being substantially horizontally disposed, having one end thereof connected to the lower end of said float, and having the other end thereof connected to said motor.

16. A sump pump of the type which includes a submersible pump, an electric motor being operably connected to said pump, an electrical switch being electrically and mechanically connected to said motor, and float means for submersion into a fluid, said float means being operably connected to said switch for actuation thereof to conducting and non-conducting conditions in respOnse to changes in the level of said fluid, the improvement which comprises: said float means includes first and second vertically spaced floats, having a weight to volume ratio such that said float means will float with one of said floats partially submerged in said fluid, for actuation of said switch to one of said conditions when said fluid is at a first level wherein said one float is partially submerged; and magnetic means, including a first magnetic element being operably connected to said float means and a second magnetic element being operably connected to said motor, for providing a restraining force to said float means thereby to prevent movement of said float means and actuation of said switch to the other of said conditions by said float means until the level of said fluid changes and the other of said floats is partially submerged.