U.S. patent number 3,874,594 [Application Number 05/354,508] was granted by the patent office on 1975-04-01 for tank cleaning machine with selective wash programming.
This patent grant is currently assigned to Butterworth System Inc.. Invention is credited to Kenneth John Hatley.
United States Patent |
3,874,594 |
Hatley |
April 1, 1975 |
TANK CLEANING MACHINE WITH SELECTIVE WASH PROGRAMMING
Abstract
A tank washing machine, suitable for cleaning the tanks of
marine oil tankers, in which washing liquid is discharged from a
nozzle mounted on a housing which is rotatable about a first axis
(e.g., vertical) in relation to other normally fixed parts of the
machine. The nozzle is pivotable or rotatable about a second axis
(e.g., horizontal) which is at an angle to the first axis. A single
driving means (preferably a single turbine powered by wash liquid)
is connected, via gears and a clutch mechanism, to rotate the
housing about the first axis and via other gears to pivot or rotate
the nozzle about the second axis, the ratio of the angular speeds
of the nozzle and housing about their respective axes being
constant, but the absolute angular speeds being varied in
accordance with a selected program (e.g., as determined by the
profile of a cam) so that distant tank walls are sprayed as
effectively as proximate walls, during use.
Inventors: |
Hatley; Kenneth John (Surry,
EN) |
Assignee: |
Butterworth System Inc.
(N/A)
|
Family
ID: |
10137131 |
Appl.
No.: |
05/354,508 |
Filed: |
April 25, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Apr 28, 1972 [UK] |
|
|
19907/72 |
|
Current U.S.
Class: |
239/227;
134/167R; 239/240 |
Current CPC
Class: |
B05B
3/0445 (20130101); B05B 3/16 (20130101) |
Current International
Class: |
B05B
3/16 (20060101); B05B 3/02 (20060101); B05B
3/04 (20060101); B05B 3/00 (20060101); B05b
003/04 () |
Field of
Search: |
;239/225,227,237,240
;134/24,167R ;416/167 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wood, Jr.; M. Henson
Assistant Examiner: Mar; Michael Y.
Attorney, Agent or Firm: Paris; F. Donald
Claims
I claim:
1. A tank washing machine suitable for cleaning tanks of oil
tankers, comprising a wash liquid supply pipe in communication with
a nozzle housing rotatable about its longitudinal axis, a nozzle
fixed to said nozzle housing, said nozzle being rotatable about an
axis at an angle to its own longitudinal axis and at an angle to
the axis of rotation of said housing, a turbine having turbine
blades actuated by the flow of wash liquid from said wash liquid
supply pipe, means operably driven in response to the impingement
of said wash liquid on said turbine blades and including program
means for causing said tanks to be cleaned in accordance with a
predetermined programmed wash cycle, said program means operably
connected for changing the speed of said turbine, and means
connecting said turbine to drive said nozzle and nozzle housing for
automatically varying the speed of each of said nozzle housing and
said nozzle during operation as a function of said predetermined
programmed wash cycle of said program means.
2. A machine according to claim 1 wherein the nozzle housing is
co-axial with the wash liquid supply pipe.
3. A machine according to claim 2 wherein said turbine is located
at the opposite end of said wash liquid supply pipe from said
nozzle housing and is connected thereto by means of a rotatable
shaft.
4. A machine according to claim 2 wherein the nozzle is rotatable
about an axis disposed at an angle of 90.degree. to the axis of
rotation of the nozzle housing.
5. A machine according to claim 4 wherein the axis about which the
nozzle is rotatable is disposed at substantially 90.degree. to its
longitudinal axis.
6. A machine according to claim 1 wherein said turbine blades have
a variable pitch and said program means are operably connected
therewith through means comprising a slidable rod co-axial with the
axis of the turbine, and means for connecting said rod with said
program means and said turbine blades so that sliding of said rod
is in accordance with said program means for varying the pitch of
said turbine blades in response thereto.
7. A machine according to claim 6 wherein said program means
comprises a rotatable cam having profile corresponding to said
predetermined programmed wash cycle, and liner means connected at
one end for sensing said profile and at the opposite end for
causing said rod to slide as a function of the sensed profile.
8. A machine according to claim 6 wherein the nozzle oscillates
about its axis of rotation.
9. A machine according to claim 8 comprising a slidable and
rotatable clutch member having faces at opposite ends thereto, each
of said faces adapted to engage with two other rotatable clutch
members respectively, and gear means connected to said other
rotatable clutch members and to the nozzle and nozzle housing so
that when an adjacent face of said slidable clutch member
disengages from engagement with one of said other clutch members
the opposite face thereof engages with the other of said clutch
members which causes a reversal in the direction of rotation of the
nozzle and nozzle housing.
10. A tank washing machine for cleaning storage tanks, comprising a
nozzle having a longitudinal axis and mounted for pivotal movement
about a first axis substantially perpendicular to said longitudinal
axis, a housing for pivotally mounting said nozzle and being
rotatable about a second axis disposed at an angle relative to said
first axis, conduit means for supplying tank wash liquid to said
nozzle, common drive means connected for rotating said housing and
for causing said nozzle to pivot in a predetermined fixed angular
velocity relationship, predetermined tank wash profile means for
defining a desired automatic wash program for cleaning said tank,
said tank wash profile means connected with said common drive means
for regulating the speed thereof as a function of said tank wash
profile means and for automatically varying the absolute rate of
angular velocity of said housing and said nozzle in accordance with
said tank wash profile means, said tank wash profile means
comprising cam means having a cam surface defining said wash
program, and cam follower means for tracking said cam surface and
connected with said common drive means for regulating the speed
thereof in response to the tracked cam surface.
11. A machine according to claim 10 wherein said common drive means
includes a turbine actuated by the flow of wash liquid.
12. A machine according to claim 11 wherein said turbine includes
turbine blades, and comprising lever means for varying the angle
between said turbine blades and the direction of flow of wash
liquid impinging thereon in accordance with the cam surface as
sensed by said cam follower.
13. A machine according to claim 12 wherein said turbine blades
have a variable pitch.
14. A machine according to claim 13 wherein said means for varying
the relative angle between said turbine blades and the wash liquid
impinging thereon comprises a slidable rod co-axial with the axis
of said turbine, and lever means connecting said rod to said
turbine blades for causing the pitch of said turbine blades to vary
in relation to the pitch of said turbine blades a vary in relation
to the sliding movement of said rod.
15. A machine according to claim 14 wherein said slidable rod is
operably connected to a first end of pivotably mounted lever means,
said lever means carrying at the opposite end thereof said cam
follower means disposed in operable tracking contact with said cam
surface.
16. A machine according to claim 15 wherein said cam means is
rotatably mounted.
17. A tank washing machine adapted for cleaning the interior of a
cargo storage tank, comprising variable speed drive actuated by
wash liquid, said speed varying automatically in accordance with a
predetermined wash program for said tank, predetermined wash
program means operably connected with said drive means for causing
the speed of said drive means to automatically vary in accordance
with said wash program for said tank, nozzle means for use in
cleaning said tank and means connecting said drive means to said
nozzle for automatically varying the speed thereof in accordance
with said wash program, whereby said tank is cleaned in a
predetermined optimum manner.
Description
This invention relates to machines for cleaning tanks.
Many machines have been described for cleaning tanks, e.g., tanks
of oil tankers. Usually the tank washing is carried out by the use
of jets of water ejected through a nozzle. On some machines the
nozzle is mounted on a housing which rotates slowly about a
vertical axis and at the same time the nozzle oscillates more
slowly about the horizontal axis. In this manner substantially the
whole of the tank wall area receives jets of water from the
nozzle.
Such machines however, have one serious defect and that is their
inability to equalize the wash water over the whole tank surface.
This occurs because the nozzle is suspended relatively close to the
underside of the tank top, and it is normal for the nozzle to
elevate a fixed amount about the horizontal axis for every turn
about the vertical axis. If the nozzle housing is rotated at a
constant rate the nozzle will take as long to travel from the
vertically downward position to the horizontal position as it will
do to travel from the horizontal position to the vertically upward
position, thereby supplying as much wash water to the top metre or
so of the tank as the whole of the rest of the tank.
We have now reduced this problem with the machine of this invention
which employs a variable speed turbine, and this results in
variations in the rotational speed of the nozzle housing and the
speed of oscillation of the nozzle about the horizontal axis.
The present invention provides a method of cleaning a tank
employing a tank cleaning machine of the type having a nozzle which
is rotatable or pivotable about a first axis substantially
perpendicular to the longitudinal axis of the nozzle, the nozzle
being mounted in a housing which is rotatable about a second axis
at an angle to the said first axis, the method comprising driving
the nozzle and the housing about their respective axes from the
same drive means with their angular velocities in a constant ratio,
and varying their absolute angular velocities in a predetermined
manner in accordance with a selected program.
In another aspect, the invention comprises a tank washing machine
comprising a nozzle which is rotatable or pivotable about a first
axis substantially perpendicular to the longitudinal axis of the
nozzle and which is mounted on a housing which is rotatable about a
second axis at an angle to the said first axis, a conduit for
supplying a tank wash liquid to the nozzle, a common drive means
connected for rotating the housing and rotating or pivoting the
nozzle in such a manner that the angular velocity of the housing
will be in a fixed ratio in relation to the angular velocity of the
nozzle, and means for varying the absolute rate of rotation of the
housing and of the nozzle, about their respective axes, in
accordance with a selected program. Preferably, the selected
program is provided by the interaction of a cam and a cam follower
which are driven from the said drive means, and the relative
movements of the cam and cam follower are employed to influence the
power output from the drive means, e.g. by varying the relative
angle between the blades of a drive turbine powdered by the wash
liquid and the angle of impingement of the wash liquid on the
blades.
According to this invention a tank washing machine suitable for
cleaning tanks of oil tankers comprises a wash liquid supply pipe
in communication with a nozzle housing rotatable about its
longitudinal axis, a nozzle fixed to the nozzle housing, said
nozzle being rotatable about an axis at an angle to its own
longitudinal axis and at an angle to the axis of rotation of the
housing, a turbine actuated by the flow of wash liquid, means
whereby, whilst the turbine is rotating, the relative angle between
the turbine blades and the flow of wash liquid impinging on the
turbine blades may be varied (e.g., by changing the altitudes of
the blades, and/or by changing the direction of liquid flow onto
the blades employing flow nozzles) and means whereby the speed of
rotation of the turbine controls the speed of rotation of the
nozzle housing and the speed of the rotation of the nozzle.
The wash liquid supply pipe is usually designed so that when the
machine is installed in position for use, at least a large part of
the pipe projects substantially vertically into the tank from the
roof of the tank. Preferably it carries an annular plate for fixing
to the hole in the roof of the tank. Part of the supply pipe may if
desired be bent, e.g., through 90.degree., so that when the machine
is fitted in position part of the supply pipe outside the tank is
for example horizontal so that it can be connected easily to the
source of wash liquid.
The nozzle housing communicates with the wash liquid supply pipe
and usually it is co-axial with this pipe, and therefore usually
rotates about a substantially vertical axis when the machine is in
position in the tank.
The nozzle is rotatable about an axis at an angle to the axis of
rotation of the housing, and usually this angle is a substantial
angle, e.g., 90.degree.. Thus, in the preferred embodiment when the
axis of rotation of the nozzle housing is substantially vertical
when the machine is in position in the tank, the axis of rotation
of the nozzle is substantially horizontal. Usually the axis about
which the nozzle is rotatable is substantially 90.degree. to its
own longitudinal axis. Generally the nozzle does not rotate
completely about its axis of rotation, but oscillates about this
axis.
The turbine is actuated by the flow of wash liquid, and the turbine
should preferably be located at the entrance to, or in the wash
liquid supply pipe.
The angle which the turbine blades make with the flow of wash
liquid affects the speed of rotation of the turbine, and preferably
it is the angle which the blades make with the longitudinal axis of
the turbine which is altered. Means can be provided which are
capable of continuously varying the angle of the turbine blades. In
the preferred embodiment this means of varying the angle of the
blades of the turbine comprises a slidable rod, co-axial with the
axis of the turbine, the sliding of which rod along the axis of the
turbine causes by means of linked levers, the variation of the
angle the blades of the turbine make with the plane at right angles
to the axis of the turbine.
The angle which the turbine blades make with the flow of wash
liquid can however be varied by having fixed turbine blades and
altering the angle at which the wash liquid impinges on the blades.
This arrangement would involve a number of substantially radial
vanes placed in the wash liquid supply pipe immediately before the
turbine, and a device for altering the angle which these blades
make with the longitudinal axis of the wash liquid supply pipe,
thereby altering the angle at which the wash liquid impinges upon
the fixed blades of the turbine.
The speed of rotation of the turbine controls the speed of rotation
of the nozzle housing and the speed of rotation of the nozzle. In
the preferred embodiment of the invention, the turbine is connected
to a rotatable shaft which rotates with the turbine blades.
Rotation of this rotatable shaft through gears and other rotatable
shafts causes rotation of the nozzle housing and the nozzle. By
this means variation in the speed of the turbine blades results in
variations in the speeds of rotation of the nozzle housing and of
the nozzle.
In the preferred embodiment of the invention the slidable rod which
varies the angle of the blades of the turbine is linked to a
pivoted lever, the other end of which is moved by a rotatable cam.
Rotation of the cam causes longitudinal shifting of the slidable
rod and hence variation of the angle of the turbine blades. By
using cams of different profile one can alter the variation in the
speed of the turbine blades.
So that the nozzle can oscillate rather than completely rotate the
machine is preferably provided with means for reversing the
direction of rotation of the nozzle periodically. This may be
achieved by means of a slidable and rotatable clutch with two
faces, each face of which can engage separately with two other
rotatable clutches. This slidable clutch is caused to slide
periodically so that it engages first one and then the other of the
other two clutches. By means of gears, rotation of one of these
clutches causes the nozzle housing and nozzle to rotate in one
direction, whereas rotation of the other clutch in the same
direction causes the nozzle housing and nozzle to rotate in the
opposite direction. Alternatively, the direction of rotation of the
nozzle about the horizontal axis may be reversed while maintaining
the direction of rotation of the nozzle housing in the same
direction.
The direction of rotation of the nozzle can of course be reversed
by other means, e.g., by means of a rotating partially toothed
wheel engaging first one gear train, and then another gear
train.
It is a preferred feature of this invention that the speed of
rotation or oscillation of the nozzle is very much less than the
speed or rotation of the nozzle housing. This is obviously achieved
by gear reduction and in practice the speed or rotation of the
nozzle housing is usually from 10 to 200 times, e.g. 20 to 60
times, that of the speed of rotation or oscillation of the
nozzle.
The tank cleaning machines of this invention will now be described
with reference to the accompanying drawings in which:
FIG. 1 shows a general elevation of a machine according to the
invention, with certain parts cut away to show the interior
thereof,
FIG. 2 is a vertical section through the top part of the machine of
FIG. 1.
FIG. 3 is a section through III--III of FIG. 2.
FIG. 4 is a section through IV--IV of FIG. 2.
FIG. 5 is a sectional elevation of the turbine and turbine shaft of
the machine of FIGS. 1 and 2.
FIG. 6 is a section through VI--VI of FIG. 5.
FIG. 7 is a vertical cross-section through the top part of another
machine in accordance with the invention.
FIG. 8 is a vertical cross-section through the bottom part of the
machine whose top part is depicted in FIG. 7, and
FIG. 9 is a horizontal cross-sectional plan on lines IX-IX of FIG
8.
Referring to FIG. 1 of the drawings, the machine 1 is mounted by
means of annular plate 2 on the top of a tank 3 with the wash
liquid supply pipe 4 passing into the interior of the tank 3. At
the lower end of the machine there is a rotatable housing 5 which
is connected to a drive tube 6 which is co-axial with and can
rotate inside the supply pipe 4. Co-axial with and inside the drive
tube 6 is a shaft 7, the lower end of which terminates in a worm 8.
This worm meshes with a worm wheel 9 which is connected to the
nozzle 10.
Referring to FIG. 2 of the drawings the turbine 11 is housed in the
horizontal portion of the wash liquid supply pipe 4 and is
connected to the hollow shaft 12 which rotates with the turbine.
Inside shaft 12 and co-axial therewith is another shaft 13, the
function of which is to be described later. Fixed to shaft 12 is
gear 14 which meshes with gear 15. Gear 15 is keyed at 16 (see also
FIG. 3) to shaft 17, but the shaft 17 is free to slide axially
through the gear 15. Attached to shaft 17 is a clutch member 18
which is capable of engaging with another clutch member 19 which is
fixed to bevel gear 20. Bevel gear 20 and another bevel gear 21 are
fixed to and mounted on a hollow shaft 22. Clutch member 18 is also
capable of engaging with a clutch member 23 which is fixed to a
bevel gear 24. The bevel gear 24 and clutch member 23 are mounted
on the hollow shaft 17, but the shaft is free to shift
longitudinally with respect to the gear 24 and clutch member 23.
Bevel gear 20 meshes with a bevel gear 25 mounted on shaft 7, and
bevel gear 21 meshes with a bevel gear 26 mounted on the drive tube
6.
Hollow shaft 17 has an internal annular shoulder 27 which serves as
journal bearing for a rod 28 which is co-axial with shaft 22. One
end of rod 28 is provided with a screw thread 29 which meshes with
an internal thread 30 of shaft 22. The other end of rod 28 is
connected to a rack 31 which has an extension 32 which can slide
longitudinally in a guide 33 (see also FIG. 4).
Mounted on rod 28 are two annular axially adjustable stops 34 and
35, in between which are compression springs 36 and 37 located
either side of the annular internal shoulder 27 of shaft 17.
Rack 31 meshes with a gear 38, which rotates when the rack moves
longitudinally. Gear 38 is coupled via shaft 39 to a cam 40. The
cam 40 moves a lever 41 pivoted at 42 which is provided at one end
with a bearing 44. This bearing 44 engages with two stops 43 on the
shaft 13. Alternatively lever 41 may be moved manually by
displacement of fulcrum pin 42.
Referring now to FIGS. 5 and 6 of the drawings the shaft 13
terminates in a square end 45. Three of the four turbine blades 46
are shown and attached to each at the inward end of each is a
pivoted lever 47 to which is fixed a pin 48. Each pin 48 engages in
a slot 49 (oblique to the longitudinal axis) in the square end 45
of the shaft. Longitudinal movement of rod 13 results in shifting
of the levers 47 thereby altering the inclination of the blades 46
about their axes, two of which are shown at 50.
The operation of the tank cleaning machine is as follows:
Wash liquid, usually water, enters the wash liquid supply pipe 4
and impinges on the blades 46 of the turbine causing the turbine 11
to rotate. The wash liquid passes down the vertical section of the
wash liquid supply pipe 4 and eventually passes out through the
nozzle 10.
Rotation of the turbine blades 46 causes shaft 12 to rotate and
with it gears 14 and 15, and shaft 17. Since clutch member 18 is
fixed to shaft 17 this clutch member also rotates, and as shown in
FIG. 2 it engages clutch member 19 which also rotates with clutch
member 18. Rotation of the clutch member 19 means that bevel gears
20 and 21 and shaft 22 on which the gears 20 and 21 are mounted
also rotate. Rotation of gears 20 and 21 also causes rotation of
bevel gears 25 and 26, and shaft 7 and tube 6 respectively. Due to
the difference in the gear ratio between gears 20/25 and 21/25
shaft 7 and tube 6 will rotate at different speeds. This in turn
means that worm 8 and housing 5 respectively will rotate at
different speeds. In practice it is usual for the gear ratios to be
chosen so that shaft 7 and hence worm 8 rotates slightly slower
than housing 5. This in turn means that worm gear wheel 9 rotates
even slower.
Whilst shaft 22 rotates its internal screw thread 30 meshes with
the screwed end 29 of rod 28. As shown in FIG. 2 this causes rod 28
to shift slowly towards the left. Rotation of this rod 28 is
prevented by means of the guide 33 preventing rotation of extension
32 of rack 31. As rod 28 moves towards the left the stop 35
gradually compresses spring 37 and at the same time spring 36 which
is initially compressed between should 27 and stop 34, becomes less
compressed. This continuous compression of spring 37 and relaxation
of spring 36 will result eventually in the clutch member 18
suddenly shifting from right to left so that it engages clutch
member 23. Since clutch member 18 is fixed to shaft 17, rotation of
the clutch members 18 and 23 occurs and with it rotation of bevel
gear 24 which is usually of the same size as and having the same
number of teeth as bevel gear 21. This means that bevel gear 26 now
rotates in the opposite direction as also does bevel gear 25
(through bevel gear 20 fixed to shaft 22 which carries bevel gear
21). It can be seen therefore that when bevel gear 25 reverses
direction so will shaft 7, and worm 8. This reversal of direction
also means a reversal of direction of rotation of worm wheel 9, and
this means that if nozzle 10 has been slowly rising it will now
slowly descend, and vice-versa.
As rod 28 moves longitudinally so will rack 31. This engages gear
38, rotation of which causes cam 40 to rotate. Rotation of the cam
causes pivoted lever 41 to pivot about the fulcrum pin 42. By means
of the bearing 44 and stops 43 movement of lever 41 causes shaft 13
to move longitudinally. As explained previously movement of shaft
13 causes inclination of blades 46 to alter, thereby altering the
angle which the blades 46 make with the flow of wash liquid. This
causes the speed of the turbine 11 to alter, and hence the speed of
rotation of housing 5 and speed of oscillation of nozzle 10.
By adjusting the position of stops 34 and 35 and by changing cams
so that different profiles are used representing different selected
washing programmes, one can readily alter the speed of rotation of
housing 5 and also the speed of oscillation of nozzle 10 to meet
the requirements of the particular tank being cleaned.
Reference is now made to FIGS. 7, 8 and 9 which illustrate the
principal constructional features of a different design of machine
in accordance with the invention. In FIGS. 7, 8 and 9, features
which are common also to the embodiment of FIGS. 1 to 6 are given
the same reference numeral.
In the embodiment of FIGS. 7, 8 and 9, the relative rotation or
angular speeds of the housing 5 and the worm 8 (and consequently
the worm gear 9) are derived by a reduction gear arrangement,
described below, in the housing 5 rather than from a reduction gear
arrangement in the top of the machine as is the case with the
previous embodiment, and the reduction gear arrangement in the
housing 5 is driven by means of a single drive shaft 50 rather than
the combination of the shaft 7 and drive tube 6 of the previous
embodiment.
Referring particularly to FIG. 7, it will be seen that the meshed
bevel gears 20, 25 of FIG. 2 are absent, and that the clutch member
19 is attached to the inwardly-directed face of bevel gear 21.
Bevel gear 21 and bevel gear 24 are both meshed with a bevel gear
26 (which may alternatively be in the form of a crown gear wheel,
not shown, as will be apparent to those skilled in this art), and
bevel gear 26 drives the single shaft 50 which extends downwards
into the rotatably-mounted housing 5.
From the description of the first embodiment, it will be apparent
that when the clutch member 18 is engaged with clutch member 19,
the rotation of the shaft 50 will be in the opposite direction to
that when the clutch member 18 is engaged with the clutch member 23
on the bevel gear 24. Accordingly, the shaft 50 will rotate a
predetermined number or revolutions in one direction and then a
predetermined number of revolutions in the opposite sense as the
clutch member 18 engages alternately with the clutch members 19 and
23. All the other functions of the parts shown in FIG. 7 are
substantially the same as the parts shown in FIG. 2, including the
arrangement previously described, by which the speed of rotation of
the turbine 11 controls the speed of rotation of the shaft 17 and
of whichever of the bevel gears 21, 24 is engaged by the clutch,
and of the bevel gear 26.
Reference is now made to FIGS. 8 and 9 from which it will be seen
that the shaft 50 is attached to the rotatably-mounted housing 5 by
means of a key and keyway 50a and locked nut 50b. The housing 5 is
mounted for rotation about the stationary vertical liquid supply
pipe 4 on bearings 4a, of which only some are shown in FIG. 8.
The liquid supply pipe 4 supports a stationary tube 51 which
terminates at its lower end in an annular recess between the shaft
50 and the housing 5. The tube 51 is provided with an external gear
ring 52. A spur wheel 53 is mounted for rotation on a stub shaft 54
which extends upwardly from the base of the housing 5 parallel
with, and offset from the axis of shaft 50, and the spur wheel 53
meshes with the gear ring 52, so that rotation of the shaft 50 and
the attached rotatable housing 5 causes planetary rotation of the
spur wheel 53 about the axis of the shaft 50. Attached to the spur
wheel 53 and mounted for rotation on the stub shaft 54 is a second,
smaller pinion wheel 55 which meshes with a spur gear 8a on the
worm 8 which is mounted, in any known suitable way, for rotation
about the stationary tube 51. The rotation of the worm 8 causes
rotation of the worm wheel 9 and hence causes changes in the
elevation or attitude of the nozzle 10 in the same way as in the
embodiment of FIGS. 2 to 6.
The gear ratios between the stationary gear ring 52 and the meshing
spur wheel 53, between the spur wheel 53 and the smaller pinion
wheel 55, and between the pinion wheel 55 and the spur gear 8a can
easily be selected to provide a desired ratio between the
rotational or angular speed of the shaft 50 and the speed of the
worm 8. Although the reduction gear arrangement within the housing
5 of the embodiment of FIGS. 7 and 8 is more expensive to make than
the simple worm-and-gear wheel assembly in the housing 5 of the
embodiment of FIGS. 1 to 6, in many cases, the overall cost of the
machine of FIGS. 7 and 8 may be cheaper than that of the machine of
FIGS. 1 to 6 since only one drive shaft (50) is required compared
with the two shafts 6 and 7, and for some duties, these shafts may
be about 12 feet long. Nevertheless, the type of tank cleaning
machine of this invention which may be preferred by the ultimate
user may be determined by operational factors which outweigh
advantages of the FIG. 7 embodiment.
The top section of the machine of FIGS. 7 and 8 can be made smaller
since the size limitations on the bevel wheels 21, 24 and 26 are
less stringent in the absence of the other two bevel wheels 20, 25
of FIGS. 1 to 6. It will be seen in FIG. 8 that the thrust of the
water jet is shared equally between bearings or sets of bearings
(which are illustrated, but not all indicated by reference
numerals) on each side of the jet reaction line. It will be clear
to those skilled in the art that bearings or sets of bearings may
be provided and so arranged in the housing 5 of FIG. 1 that the
water jet thrust is shared between a plurality of bearings.
In order to enhance further the washing operation which can be
performed by machines in accordance with the invention, the worm 8,
as shown in FIG. 8, is free to slide axially a short distance along
the support tube 51 between a lower shoulder 57 in the housing 5
and an upper shoulder 58 in the housing 5. A suitably short
distance is one-half of the product of the speed reduction ratio of
the gear-train 52, 53, 55, 8a and the pitch of the worm, or
approximately this product.
When the direction of rotation of the shaft 50 is reversed due to
the previously-described change of engagement of the clutch member
18 with the clutch members 19 and 23, the change in direction of
the reaction of the worm 9 on the worm 8 will cause the worm 8 to
move axially along the shaft 50 in the space between the lower
shoulder 57 and the upper shoulder 58. The final position of the
worm 8 will be at an abutting location with one or other of the
shoulders 57 or 58, thereby imparting to the worm gear 9 and the
attached nozzle 10 a starting position on reversing the direction
of angular movement which is non-coincident with their positions
prior to reversal of direction of angular motion, due to lost
motion in the gear train 52, 53, 55, 8a, 8, 9 as outlined above,
and equal to about one-half of the effective pitch of the gear
train. The non-coincident position of the nozzle 10 at each
reversal is advantageous in mitigating any tendency of the wash
water jet leaving the nozzle 10 to make substantially repetitive
wash patterns in the tank thereby further improving the
thoroughness of washing that can be effected by the machine of the
invention. It will be apparent to those skilled in the art that the
worm 8 of the embodiment of FIGS. 1 to 6 can also be arranged for
limited axial movement relative to the housing 5 for the same
purpose.
In FIG. 9, there are shown the flow apertures 60 at the end of the
nozzle 10 within the housing 5 through which wash water passes from
regions 61 of the housing 5 to the nozzle 10. Wash water is
supplied to the regions 61 from the wash water supply pipe 4, as
shown in FIG. 8, via apertures 62 at the lower end of the pipe 4
within the rotatable housing 5 from which it passes into the spaces
63 of the housing 5 which communicate via apertures, not shown,
with the regions 61. Although the manner in which wash water or
other wash liquid is passed to the nozzle 10 has been particularly
described with reference to FIGS. 8 and 9, it will be appreciated
by those skilled in the art that the same or a similar arrangement
can be used in other embodiments of the invention.
In the foregoing description, reference has been made only to the
principal parts of the machines of the invention, but it will be
understood by those skilled in the art that there will be other
parts such as bearings between relatively rotatable parts, and
glands and seals to prevent undesirable leakage of liquids.
It will be appreciated by those skilled in the art that features
which have been described or mentioned with particular reference to
one of the two illustrated embodiments may be incorporated in the
other of the two embodiments, without departing from the invention
as defined in the appended claims.
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