Shaft driven pump without seals

A sealless fluid pump apparatus has a primary pump moving fluid from an inlet through an outlet of the apparatus and a secondary pump adjoining the primary pump. Shaft means driving the two pumps extends through a portion of the housing separating the two adjoining pumps as well as through another portion of the housing separating the two pumps from a motor or other means driving the shaft means. No seals are provided where the shaft means extends through the housing. Rather, the secondary pump operates to resist the flow of fluid between the shaft means and housing into the secondary pump.

BACKGROUND OF THE INVENTION 
The invention relates to apparatus for pumping fluids and more 
particularly, to a design for a shaft driven pump for liquids which 
eliminates the necessity of a seal about the driving shaft where it enters 
the pump casing. 
Pumps are typically either of a shaft or shaftless design. This invention 
relates to the former. Such pumps typically comprise a motor or some other 
driving mechanism, a pump casing or chamber housing a rotor or other 
impeller and a shaft connecting the driving mechanism to the impeller for 
actuating the same. A mechanical seal is generally provided about the 
shaft where it penetrates the pump chamber so as to prevent leakage of the 
fluid being pumped and to otherwise maintain fluid pressure created by the 
impeller to assure efficient pumping. 
There are significant negative aspects associated with such seals. 
Typically, seals are subject to wear or damage necessitating their 
replacement as well as possible replacement of the shaft. Also, contact 
between the seal and the shaft causes frictional drag upon the shaft 
reducing pump efficiency. Moreover, a sufficiently high initial torque 
must be provided to overcome standing friction between the seal and the 
shaft when the latter is initially rotated imposing further constraints on 
the motor or other drive mechanism selected to drive the impeller. 
Various "sealless" pump designs have been proposed to overcome some of 
these problems. For example, U.S. Pat. No. 4,065,232 describes a 
vertically oriented shaft driven "sealless" centrifugal type fluid pump. 
Fluid leaking from the pump chamber rises about the shaft into a sealed 
adjoining upper chamber where gas is introduced to control the level of 
the fluid. A conduit is provided to the inlet of the pumping chamber and 
is used to remove excess fluid from the upper chamber. This system 
requires a gas source as well as auxiliary equipment controlling the 
introduction of gas into and monitoring the level of fluid within the 
upper chamber. 
As will be described subsequently in greater detail, applicant's invention 
involves the use of a second impeller in a sealless pump design to control 
fluid leakage from a primary pumping chamber along the pump drive shaft. 
Of relevance to this aspect of my invention is British Pat. No. 1,389,222. 
That patent describes a vertically oriented shaft driven pump for liquid 
fuels having a primary pump chamber at the bottom of a pump housing, a 
secondary pump chamber above the primary pump chamber and a motor housing 
above the two pumping chambers. A shaft extends from the motor through the 
secondary chamber and into the primary chamber where it drives a primary 
pump centrifugal type rotary impeller. The shaft also drives a secondary 
centrifugal type rotary impeller in the secondary pump chamber which 
removes liquids leaking into the secondary chamber and draws air from the 
motor housing to prevent fumes from the pumped fuel from invading the 
motor. The indicated design does not dispense with seals as a conventional 
mechanical seal is supplied around the shaft between the primary and 
secondary pumping chambers. Lastly, a separate outlet must be provided for 
the removal of fluids (fuel, fumes and air) from the secondary chamber, 
additionally complicating its design and increasing manufacturing costs. 
Also of relevance to the multiple impeller aspect of my invention is a 
class of fluid pumps represented by U.S. Pat. Nos. 4,088,424 and 4,226,575 
used with wet pickup vacuum cleaners and/or rug shampooers. Each patent 
describes a pump apparatus comprising a plurality of impellers mounted 
upon and driven by a common shaft for rotation. The impellers operate in 
two chambers defined by walls of the apparatus housing. A fluid path is 
provided between the chambers by an opening about the impeller drive 
shaft. Fluid entering the apparatus and first chamber through an inlet is 
urged through the opening and into the second chamber where other 
impellers urge the fluid towards an outlet from that chamber and the 
apparatus. The function of at least one impeller in the second chamber of 
each invention is to create a pressurized air barrier preventing the fluid 
being pumped, a mixture of air, moisture and perhaps other liquids, from 
travelling to the base of the impeller drive shaft and into contact with 
the motor or its bearings. The one impeller acts as a blower drawing air 
from an external source and pumping it under pressure into the fluid being 
moved by the remaining impellers causing the pumped fluid to continue 
along a path towards the outlet. The air seal thus formed by the 
pressurized air is undesirable in certain applications as air is mixed 
into the fluid being pumped. It is also believed the system would be 
ineffective against fluids which are entirely or primarily liquid. 
OBJECT OF THE INVENTION 
It is a first object of the invention to provide a novel design for a 
sealless pump. 
It is yet another aspect of the invention to provide a sealless pump of 
simple design which is easy to manufacture. 
It is yet another object of the invention to provide a sealless shaft 
driven liquid pump which does not mix air into the liquid being pumped. 
It is yet another object of the invention to provide a pump of sealless 
design for use with an ice making apparatus which does not entrap air in 
the pumped water. 
SUMMARY OF THE INVENTION 
The aforesaid objects of the invention and other objects are accomplished 
by my invention in which an apparatus is provided having a first or 
primary pump means for pumping fluid in a conventional fashion between an 
inlet and an outlet of an apparatus. The first pump means is driven by 
shaft means extending through a wall of the first pump means. In lieu of a 
conventional mechanical fluid seal, a first fluid gap is provided through 
the wall and about the shaft. Thus, although the shaft is free to rotate 
without the constrictions imposed by a contacting mechanical seal, fluid 
can escape primary pump means through the fluid gap. A second pump means 
is provided in fluid communication with said first gap and driven by the 
same shaft means for resisting the flow of fluid through the first fluid 
gap from the first pump means. 
According to a preferred embodiment of my invention, a housing is provided 
having a first or primary pumping chamber and a second or secondary 
pumping chamber adjoining the primary pumping chamber. A first or primary 
impeller is provided in the primary pumping chamber to form with the 
primary chamber a primary pump which moves fluid entering the apparatus 
through an inlet leading into the primary chamber, to and through an 
outlet leading from the primary chamber and apparatus. Shaft means from a 
motor or other shaft driving means is provided extending through the 
secondary pumping chamber and into the primary chamber to drive the 
primary impeller. A first partition means of the apparatus housing 
separates and forms walls of the adjoining primary and secondary pumping 
chambers. A second partition means of the housing forms a second wall of 
the secondary pumping chamber and separates the primary and secondary 
pumping chambers from the remainder of the apparatus including the motor 
or other shaft driving means. Each partition means has a central opening 
through which the shaft means extends. A fluid gap is provided between the 
surface of the shaft means and the opening of each of the partition means 
where, in conventional designs, a mechanical seal would normally be 
provided. A portion of the fluid entering the primary chamber passes 
through the first gap between the first partition and shaft means and into 
the secondary pumping chamber. A centrifugal type second or secondary 
rotary impeller is provided in the secondary pumping chamber and is also 
driven by the aforesaid shaft means. Fluid entering the secondary chamber 
eventually enters and primes the secondary impeller. The primed secondary 
impeller resists the flow of the fluid into the second chamber and towards 
the second gap between the second partition opening and the shaft means. 
The design requires only the provision of the second pump (i.e. secondary 
pumping chamber and secondary impeller) in place of a conventional 
mechanical seal to control leakage of the pumped fluid along the shaft 
while the primary pump is operating. 
According to one important aspect of the described preferred embodiment of 
the invention, the shaft means is multipieced. A primary rotary impeller 
is provided in the primary pump and has a first shaft extending therefrom 
which is sufficiently long to extend through the first partition means and 
into the secondary pump. A second shaft is provided extending from the 
motor or other drive means and is joined by suitable means with the first 
shaft. 
According to one important feature of the preferred embodiment, the primary 
impeller and first shaft are formed monolithically to simplify assembly 
and reduce costs. 
According to yet another important aspect of the preferred embodiment, the 
second pump is provided with a centrifugal type rotary impeller having a 
central bore through which an end of the first shaft is passed for 
engagement of the second impeller with the first shaft. The first shaft is 
tapered along at least a portion of its length as it extends away from the 
first impeller and the second impeller is press fitted into frictional 
contact engagement with the other surface of the first shaft along the 
tapered portion of its length. This also simplifies assembly and reduces 
costs. 
According to yet another important feature of the invention, where either 
rotary impeller is of the centrifugal type and is formed by a plurality of 
radially extending vanes, a backing plate is also provided so as to limit 
the amount of air drawn by the impeller and mixed with the pumped fluid. 
This is an advantage in some applications such as pumping water for 
icemaking where the mixture of air into the pumped water causes undesired 
clouding of the ice subsequently formed. 
The preferred embodiment of the invention is designed to pump water into a 
reservoir maintained at a level above the primary and secondary pumping 
chambers. Thus a head remains at the outlet when the pump is turned off 
forcing water above the two pump chambers. To prevent water from 
contacting the motor or other drive mechanism, the pump is vertically 
oriented with the primary pumping chamber located at the bottom and the 
motor at the top. A third portion of the housing, a reservoir chamber, is 
provided beneath the motor or drive means and above the primary and 
secondary pump chambers to raise the motor above the water level of the 
reservoir with which the apparatus is used. The secondary pump moves water 
which has entered the reservoir chamber when the apparatus is not pumping, 
from that chamber and through the first fluid gap into the primary pump 
for pumping from the apparatus.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 depicts in an exploded view, a preferred embodiment of the present 
invention which is a small water pump apparatus 10 designed for use with 
an ice maker. A base piece 12, an upper assembly 14 and a partition plate 
44 between the two are the primary components of a housing of the 
apparatus 10. A floor 16 and cylindrical sidewall 18 of a primary pumping 
chamber 20 are formed by interior surfaces of base 12. A fluid inlet 22 is 
provided at the bottom of the base 12 leading to an opening 24 
approximately in the center of the floor 16. Fluid entering the primary 
pumping chamber through the inlet 22 and opening 24 is pumped through an 
opening 26 (See FIG. 6) in the sidewall 18 leading to outlet 28 extending 
from the primary pumping chamber 20 and the apparatus 10. A pair of tabs 
30 each having a bore 32 extending vertically therethrough are provided on 
either side of the base 12 for attachment to upper assembly, as will be 
later described. A primary centrifugal acting rotary impeller 32 is formed 
by a backing plate 34 and a plurality of radial vanes 36 extending from 
the lower surface of the plate 34 as shown in FIG. 1. The vanes 36 are 
curved as they extend radially outward from the "eye" or center of the 
impeller 32 to reduce cavitation and improve pump efficiency. One skilled 
in the art will appreciate that the vanes 36 may also be formed to extend 
outwardly in a straight fashion parallel to radii from the center of the 
impeller 32, if desired. One so skilled will further appreciate that other 
types of rotary impeller and other shaft driven types of pumps may be 
suitable for use as the primary pump. A short hollow shaft 38 extends from 
the upper surface 37 of the backing plate 34. The impeller 32 and shaft 30 
may be formed monolithically from plastic or other suitable materials to 
reduce assembly steps and costs. The impeller portion 32 of the assembly 
30 is positioned with the primary pumping chamber 20 in the base 12 for 
operation. The partition plate 40 has a central opening 42 and upper and 
lower opposing surfaces 44 and 46 between which the opening 42 extends and 
is positioned over the impeller 32 with the short shaft 38 extending 
through the opening 42. A suitable recess 48 is provided in the top of the 
base 12 to receive the plate 40. The lower surface 46 of the plate 40 
defines the upper wall of the primary pumping chamber 20. A second rotary 
impeller 50 having a central bore 52 is positioned over the plate 40 with 
the upper end 38a of the shaft 38 extending through the bore 52. For 
convenience of assembly, the shaft end 38a is preferably slightly inwardly 
tapered along its length and the opening 52 dimensioned to allow the 
secondary impeller 50 to be jam fitted into frictional engagement with the 
shaft 38. Of course, other conventional methods may be employed to fixedly 
mount the impeller 50 to the shaft end 38a. The secondary impeller 50 is 
also of the centrifugal type and is formed by a backing plate 54 and a 
plurality of straight, radially extending vanes 56 projecting upwardly 
from an upper surface 51 of the backing plate 54 (as viewed in FIG. 1) 
away from the primary chamber 20. Again one skilled in the art will 
appreciate that curving vanes similar to the vanes 36 of the primary 
impeller 32 or other rotary impeller configurations may be employed, if 
desired. 
The upper housing assembly 14 of the pump 10 includes a plate 90 mounting a 
motor or other shaft driving means, indicated diagrammatically by a 
cylinder 60. A third, "reservoir" chamber 64 is formed beneath the 
mounting plate 90 by a hollow cylindrical section 62 and the upper surface 
67 of the second partition plate 66. By way of example, the upper surface 
67 of the second partition plate 66 and lower surface of the mounting 
plate 90 may be grooved to receive the edges of a separate cylinder 62 as 
depicted, for one assembly technique, or the mounting plate 90, cylinder 
62 and second portion plate 66 or any adjoining pair fabricated as an 
integral component. 
A shaft 70 is provided extending from the motor or other drive means 60 to 
rotate the primary and secondary impellers 32 and 50. It will be 
appreciated by one skilled in the art that a conventional electric motor 
may be provided as the means 60 or that a mechanical or electromechanical 
linkage may be provided between the shaft 70 and a distantly located power 
source for operation of the apparatus 10. The second partition plate 66 
has a central opening 68 through which the shaft 70 extends. A second 
cylindrical section 72 forms with a lower surface 69 of the second 
partition plate 66 and the upper surface 44 of the first partition plate 
40 a secondary pumping chamber 74 within which the secondary impeller 50 
operates. Thus, the second partition plate 66 forms an upper wall of the 
secondary pumping chamber 74 and serves to separate the two chambers 20 
and 74 from the remainder of the apparatus 10. The primary chamber 20 and 
shaft driven primary impeller 32 comprise a primary pump while the 
secondary chamber 74 and secondary impeller 50 comprise a secondary pump. 
A stationary vertical plate 49 is provided in the second pump to break up 
vortices which tend to form beneath the backing plate 54, but is optimal. 
The apparatus 10 is assembled as follows. After the first partition plate 
40 has been placed over the shaft 38 of the assembly 30, the secondary 
impeller 50 is jammed into frictional engagement with the tapered end 38a 
of the shaft 38. The assembly 30 is hollow along its center and the 
opening 38b of the shaft 38 has been "D" keyed to receive a similarly 
contoured end 70b of the shaft 70. The end 70b of the shaft 70 is fixed to 
the first hollow shaft by suitable means such as a screw 76 extending 
upward through the hollow interior of the assembly 30 and into the end 70b 
of the shaft 70. The upper portion 14 of the housing is then joined to the 
base 12. The second cylindrical section 72 has a slightly recessed lower 
cylindrical surface 72b which fits into a suitably contoured mating 
surface 78 of the base 12 with an O-ring seal 80 therebetween. The base 12 
is held to the upper assembly 14 by suitable means such as a pair of bolts 
82 which are inserted through the bores 32 of the tabs 30 and through 
bores 84 of tabs 86 provided in the mounting plate 90 and are each held in 
place by a nut 88 or other suitable fastening means. The mounting plate 90 
is provided with a pair of larger tabs 90a with bores 90b for mounting the 
apparatus 10 to an appropriate support. Thus assembled, rotation of the 
shaft 70 by the drive means 60 causes similar simultaneous rotation of the 
primary and secondary impellers 32 and 50. 
The assembled pump 10 is depicted in vertical and bottom views in FIGS. 2 
and 3, respectively. The assembled pump 10 has been partially broken away 
in FIG. 2 to reveal the primary impeller 32 positioned in the primary 
pumping chamber 20 and the secondary impeller 50 in the secondary pumping 
chamber 74 above the primary chamber 20 as well as the third reservoir 
chamber 64 between the secondary chamber 74 and the shaft driving means 
60. As can be seen in FIG. 2 and better seen in FIGS. 5 and 4, a first gap 
100 exists between the opening 42 of the first partition plate 40 and the 
outer diameter of the short shaft 38 and a second gap 102 exists between 
the opening 68 of the second partition plate 66 and the outer diameter of 
the short shaft 38. 
Fluid flow during operation of the pump 10 of FIGS. 1-5 is depicted in FIG. 
6 which is a side-sectioned vertical view of the lower portion of the 
apparatus 10. Incoming fluid, indicated by heavey solid lined arrows 106 
enters the pump assembly 10 and primary pumping chamber 20 through the 
inlet 22 and opening 24, respectively. Rotation of the primary impeller 32 
causes a pressure differential to be created with a lower pressure at the 
eye or center of the primary impeller 32 drawing the fluid 106 into the 
primary pumping chamber 20 and a higher pressure at the radial extremities 
of the impeller 32 moving the fluid towards the side wall 18 and through 
the opening 26 and outlet 28. Although most of the fluid will flow through 
the opening 26, a portion of the fluid, indicated by the lighter 
solid-lined arrows 106a will also flow around the radial edge of the 
impeller 32 and through a space 108 between the radial edge of the 
impeller 32 and cylindrical wall 18 of the chamber 20. The fluid 106a, 
pressurized by the impeller 32, flows towards the short shaft 38 and 
through the first fluid gap 100 into the secondary pumping chamber 74. The 
fluid 106a continues travelling between the upper surface 44 of the first 
partition plate 40 and beneath the backing plate 52 of the secondary 
impeller 50, around a space 110 between the radial edge of the secondary 
impeller 50 and the inner surface of the cylindrical section 72 forming 
the sidewall of the secondary pumping chamber 74 and towards the gap 102 
between the second partition plate 66 and the outer diameter of the short 
shaft 38. As this fluid 106a enters the secondary impeller 50 (i.e. enters 
the area swept by the vanes 56), it primes the secondary pump formed by 
the impeller 50 and chamber 74. The centrifugal action of the rotating 
impeller 52 creates a pressure differential in the fluid 106a urging it 
away from the eye of the secondary impeller 50 and the second gap 102. 
Depending upon the design of the secondary pump (i.e. second impeller 50 
and chamber 74), flow of the fluid 106a towards the second gap 102 will be 
slowed or, preferably, halted. In the indicated embodiment, flow of the 
fluid through the second fluid gap 102 will be determined by a number of 
factors including the fluid head at the inlet 22, the relative diameters 
of the two impellers 32 and 50 and the space between the top of the second 
impeller 50 and lower surface 69 of the second partition plate 66. This 
space has been greatly exaggerated in FIGS. 2 and 6 for clarity. One way 
in which to prevent fluid from entering the second gap 102 is to make the 
diameter of the second impeller 32 (as measured normal to the shaft 38) 
sufficiently greater than that of the primary impeller 32. Where no 
appreciable fluid head occurs at the inlet 22, a second impeller 50 
diameter approximately equal to that of the first impeller 32, as 
depicted, will typically suffice. In this case, the fluid will be held at 
some equilibrium radius from the center of the impeller 50 and gap 102 
while the impellers 50 and 32 are being rotated. Furthermore, this is true 
regardless of the speed of rotation of the impellers in the depicted 
embodiment. 
The apparatus depicted in FIGS. 1 through 6 is designed to pump water into 
the holding tank of an associated ice making apparatus (not depicted) 
where the level of the water is typically held above the height of the two 
impellers 32 and 50. Thus, a fluid head is maintained at the apparatus 
outlet 28 and opening 26 which causes water to flow back from the holding 
tank into the apparatus 10 and to rise through the first and second gaps 
100 and 102, respectively, and into the reservoir chamber 74 when the 
impellers 32 and 50 are not being driven. The reservoir chamber 74 raises 
the drive means 60 above the highest level of the water in the associated 
holding tank (not depicted). When the drive means 60 is reactivated, the 
impeller 50 moves fluid from the reservoir chamber 74 through the second 
gap 102 and first gap 100 and into the primary pumping chamber 20, as is 
indicated by the lighter broken-lined arrows 112, until the reservoir 
chamber 74 is drained and an equilibrium fluid position is again reached 
in the second impeller 50. 
The backing plates 34 and 54 of the primary impeller 32 and secondary 
impeller 50, respectively, prevent either impeller from drawing and mixing 
air into the fluid being pumped. In icemaking applications, injected air 
causes pumped water to freeze into a cloudy ice which is less appealing. 
They further improve the efficiency of the two impellers 32 and 50. 
There are no mechanical seals to wear or to otherwise impede movement of 
the shaft portions 38 and 70. The secondary impeller 50 contributes 
virtually no drag until that impeller is primed. Moreover, even when 
primed, the secondary impeller 50 generates less drag than normally will 
be generated by a conventional mechanical seal. As more fluid enters the 
area swept by the secondary impeller 50, it becomes better primed and its 
pumping action more efficient. The depicted embodiment operates to prevent 
the upward migration of the water through the second fluid gap 102 over 
the entire operation range of the apparatus, even where the outlet 28 has 
been sealed. 
Turning now to FIG. 7, there is shown an alternate design upper housing 
assembly 114 which is substantially identical to the upper housing 
assembly 14 of FIG. 1. A reservoir chamber 162 of the alternate assembly 
114 has been considerably diminished in size by the provision of a 
cylindrical section 162 having an inner diameter only slightly larger than 
the outer diameter of a pump driving shaft 170. Also, an outlet 92 has 
been provided in the side of the cylinder 162 to carry away liquid which 
may surge upward from the primary and secondary pumping chambers (i.e. 
chambers 20 and 74, respectively, of FIG. 1) when rotation of the shaft 
170 is halted. Such a housing 114 may also be useful where the secondary 
pump is designed to slow but not completely stop the flow of fluid through 
the second fluid gap 102. The lower edge 166a of the second partition 
plate has been shown contoured to mate with a cylindrical section 72 but 
may be formed integrally therewith. Shaft driving means are again 
indicated diagrammatically by a cylinder 160. 
It will be appreciated by one skilled in the art that where there is no 
danger that a fluid head will be created at either the inlet 22 or outlet 
28 of the apparatus 10 which will force the fluid being pumped above the 
secondary pumping chamber 74 when the shaft 70 is not being driven and if 
the secondary impeller 50 is designed to produce a maximum pressure in the 
fluid at least as great as the maximum pressure produced by the primary 
impeller 32, the reservoir chamber 64 will not be needed to protect the 
drive means 60 from the fluid being pumped. It should further be 
appreciated that for the envisioned use of the depicted preferred 
embodiment (i.e. in conjunction with an ice maker) that the major 
components of the embodiment (with perhaps the exception of the fasteners 
76, 82, and 88, the O-ring 80 and shaft 70) can be easily formed formed 
molded plastic material for ease of construction and assembly and reduced 
cost. 
While a preferred embodiment of the invention has been described and some 
modifications thereto suggested, other modifications to the operation and 
components of the preferred embodiment will no doubt appear to those 
skilled in the art. Therefor, the above description of the invention 
should be considered exemplary only and not as a limitation upon its scope 
which is more properly defined by the following claims.