US3242692A

US3242692A - Shaft and housing connection

Info

Publication number: US3242692A
Application number: US346912A
Authority: US
Inventors: Edmund G F Sweet
Original assignee: Beatty Bros Ltd
Current assignee: GSW Inc; Beatty Bros Ltd
Priority date: 1963-03-23
Filing date: 1964-02-24
Publication date: 1966-03-29
Anticipated expiration: 1983-03-29

Description

March 29, 1966 E. G. F. SWEET 3,242,692

SHAFT AND HOUSING CONNECTION Filed Feb. 24, 1964 FIG.3 FIG.4

INVENTOR EDMUND 6. F. SWEET ATTORNEYS United States Patent 3,242,692 SHAFT AND HOUSING CONNECTION Edmund G. F. Sweet, Fergus, Ontario, Canada, assignor to Beatty Bros. Limited, Fergus, Gntario, Canada Filed Feb. 24, 1964, Ser. No. 346,912 Claims priority, application Canada, Mar. 23, 1963, 871,576 2 Claims. (Cl. 644) This invention relates to an improvement in the construction of devices having a rotatably mounted prime mover and a driven element connected thereto by means of a drive shaft. More specifically, it relates to the interconnection of the prime mover and the driven element through the drive shaft. A common example of the type of device to which the'invention relates is a device known as a sump pump which has the motor at one end and an impeller assembly at the other end interconnected by means of a rigid tubular housing for a drive shaft.

The example of the sump pump is a very well known one and the problem of aligning the journal from which the motor power is taken with the journal that drives the pump impeller has always been a challenge to manufacturers. The shaft that interconnects the journal in the pump with the journal in the motor has, by custom, been a rigid one and misalignment between the bearings within which the journals rotate has always been a source of bearing noise, wear and second power loss. The same objectionable characteristics are also caused by deviation from perfectly straight of the rigid interconnecting shaft. It will be apparent that the free end of a rigid deviating shaft will wobble or trace out a circular locus as it rotates and any attempt to restrain or contain the deviation in the locus of the free end of the shaft as it rotates in a bearing will cause wear and noise in the restraining bearing.

This invention overcomes difficulties of the prior art and achieves an interconnection of the prime mover and driven element in devices such as sump pumps with a minimum of noise, wear and second power loss. According to the invention, a flexible, resilient drive shaft as distinct from a rigid drive shaft is used to interconnect the prime mover with the driven element. The principal axis of rotation of the bearing for the motor is misaligned with the principal axis of rotation of the bearing for the impeller whereby the principal axis of rotation of the journal associated with the motor is misaligned with the principal axis of rotation of the journal of the impeller. The misalignment of the motor and impeller bearings is at least large enough to flex the resilient drive shaft and maintain the misalignment of the journals constant as the motor rotates the impeller through the flexible resilient drive shaft.

The invention will be clearly understood after reference to the following detailed specification read in conjunction with the drawings.

In the drawings:

FIGURE 1 is a side view, partially in section, of a sump pump according to the invention.

FIGURE 2 is a view along the line 22 of FIG- URE 1.

FIGURE 3 is a schematic illustration of the interconnection of the sump pump motor and the sump pump impeller and,

FIGURE 4 is a view along the line 44 of FIGURE 3.

The sump pump shown in the drawings has a composite housing comprising a motor housing and a pump housing 12 interconnected by a tubular shaft housing 14 that rigidly connects at one end with the motor housing 10 and at the other end with the pump housing 12. The general construction of the motor, the pump and the housing is well known and not referred to in detail in Patented Mar. 29, 1966 this specification. Numeral 15 refers to a standard float switch control for the motor.

The motor rotor is the prime mover of the unit and it is rotatably mounted within the motor housing 10 in a bearing 16 in known fashion. The journal 18, in this case the power take-off from the motor, rotates within the bearing 16 and its free end is rigidly connected to the free end of a flexible, resilient shaft 20 by means of the rigid coupling 22 that has set

screws

24 and 26 that threadedly engage in the body thereof and exert a clamping force on the journalled free end of the shaft 18 and on the free end of the drive shaft 20 respectively.

In this specification, the principal axis of rotation of the bearing 16 is concentric with the bearing surface thereof and the principal axis of the journal is the central longitudinal axis thereof. Because of tolerance between the bearing and journal, the principal axis of the journal may not be coincident with the principal axis of the bearing.

Shaft 20 has a journal 28 sweat-soldered to its other end and journal 28, is, in turn, mounted for rotation in the bearing 30. Bearing 30 is carried by the housing 12 of the pump assembly as indicated. Here again, the principal axis of the bearing 30 is concentric with the surface thereof and the principal axis of the journal 28 is the central longitudinal axis thereof and the two axes are not coincident because of tolerances. The pump impeller 29 is carried by the journal 28.

According to the invention, the principal axis of the bearing 16 for the journal 18 is misaligned with respect to the principal axis of the bearing 30' for the journal 28 whereby, of course, the principal axis of rotation of journal 18 is misaligned with respect to the principal axis of rotation of the journal 28. In FIGURES 3 and 4 of the drawings, which are views taken at right angles to each other, the misalignment is represented by the letter x in FIGURE 3. This view is taken in a plane in which the misalignment is a maximum so that the misalignment in the plane at right angles thereto illustrate in FIGURE 4 is zero.

The shaft 20 is flexed to accommodate the misalignment of the journals and the resilience of the shaft, which tends to cause it to assume a normal position, constantly urges the journal 28 in the direction of the arrow 32 in FIGURE 3. The misalignment of the bearings is great enough that the shaft 20 is fixed during its full rotation of 360 so that the flexibility of the shaft always exerts a force in the direction of the arrow 32 as shown in FIGURE 3. The misalignment of the journals then is always a constant and equal to the dimension x viewed in FIGURE 3. The flexibility and resilience of the shaft 20 thus tend to cause the journal 28 to assume a constant position within its bearing 30 with the result that noise and wear is reduced to a minimum. A drive shaft in a standard sump pump has a diameter of about /2". This is a rigid shaft. By reducing the diameter to A", it becomes flexible. The reduction actually reduces the rigidity of the shaft by 16 times and the eccentricity described above can be incorporated with no increase in pump bearing load. The necessary eccentricity for the invention is less than 16 times the probable misalignment of the free end of the rigid shaft in the pump bearing with the standard design.

The shaft 20 being designed for flexibility is less in weight and in material cost. The invention, therefore, in addition to providing the more quiet operation reduces manufacturing costs. The rigid coupling 22 used with the invention is also a relatively cheap component because a rigid shaft as used in accordance with the practice of the prior art requires a flexible and more expensive coupling to be used in place of the coupling 22. It will also be apparent that tolerances in the components can be relaxed because the amount of misalignment necessary to make this invention Work is not as critical as the alignment that was necessary in connection With the bearings of the prior art wherein rigid shaft was used.

Embodiments of the invention other than the one illustrated will be apparent to those skilled in the art and it is not .intended that this invention should be limited to the embodiment described herein.

What I claim as my invention i825 1. In a device for transmitting power from a rotary prime mover to a driven element, said prime mover having a first journal extending therefrom, a housing enclosing said prime mover, a tubular shaft housing having aligned openings at each end, bearing means mounted in each opening, one of said bearing means being connected to said housing and the other of said bearing means being connected to said shaft housing, said first journal rotating in said first bearing, a second journal rotating in said second bearing, a coupling secured to said first journal, the axis of said one of said bearing means, said first journal and said coupling being concentric to the axis of said shaft housing, the axis of said other of said bearing means and said second journal being eccentric to the axis of said shaft housing, a resilient shaft having one end secured in said coupling and the other end secured in said seoond journal whereby said shaft is flexed and maintained in a stressed condition. I

2. In a device of the class specified in claim 1 in which said shaft is rigidly connected to said first journal.

References Cited by the Examiner UNITED STATES PATENTS 1,145,967 7/1915 Bernhard et a1 308-62 1,260,080 3/1918 Singer 642 3,037,573 6/1962 Larsen 641 X 3,155,187 11/1964 De Loren 64l X BROUGHT ON G. DURHAM, Primary Examiner.

H. C. COE, Assistant Examiner.

Claims

1. IN A DEVICE FOR TRANSMITTING POWER FROM A ROTARY PRIME MOVER TO A DRIVEN ELEMENT, SAID PRIME MOVER HAVING A FIRST JOURNAL EXTENDING THEREFROM, A HOUSING ENCLOSING SAID PRIME MOVER, A TUBULAR SHAFT HOUSING HAVING ALIGNED OPENINGS AT EACH END, BEARING MEANS MOUNTED IN EACH OPENING, ONE OF SAID BEARING MEANS BEING CONNECTED TO SAID HOUSING AND THE OTHER OF SAID BEARING MEANS BEING CONNECTED TO SAID SHAFT HOUSING, SAID FIRST JOURNAL ROTATING IN SAID FIRST BEARING, A SECOND JOURNAL ROTATING IN SAID SECOND BEARING, A COUPLING SECURED TO SAID FIRST JOURNAL, THE AXIS OF SAID ONE OF SAID BEARING MEANS, SAID FIRST JOURNAL AND SAID COUPLING BEING CONCENTRIC TO THE AXIS OF SAID SHAFT HOUSING, THE AXIS OF SAID OTHER OF SAID BEARING MEANS AND SAID SECOND JOURNAL BEING ECCENTRIC TO THE AXIS OF SAID SHAFT HOUSING, A RESILIENT SHAFT HAVING ONE END SECURED IN SAID COUPLING AND THE OTHER END SECURED IN SAID SECOND JOURNAL WHEREBY SAID SHAFT IS FLEXED AND MAINTAINED IN STRESSED CONDITION.