U.S. patent number 3,824,771 [Application Number 05/362,685] was granted by the patent office on 1974-07-23 for gas and particulate solid material separating and solid material discharging apparatus.
This patent grant is currently assigned to Central Texas Iron Works, Inc.. Invention is credited to John K. Williams.
United States Patent |
3,824,771 |
Williams |
July 23, 1974 |
GAS AND PARTICULATE SOLID MATERIAL SEPARATING AND SOLID MATERIAL
DISCHARGING APPARATUS
Abstract
Apparatus for separating particulate solid material from a
stream of gas, such as air, entraining such material includes a
blower, a solids collection receptacle, ducting connected to the
blower and to the receptacle and communicating with a source of gas
with entrained particulate solid material, the blower, receptacle
and ducting providing a substantially closed system in which gas is
recirculated, the solid material being separated from the
circulating gas and deposited in the collection receptacle. A
portion of the circulating gas, usually not exceeding 30 percent by
volume, is bled from the circulatory system and discharged to
maintain the average pressure in the circulating system at a
desired low value so as to prevent leakage blow-out of gas and
entrained dust or fine solids. Means for bleeding gas off from the
system is situated within structure housing the blower and a
separation chamber. The solids collecting receptacle is mounted so
as to be bodily movable away from the blower and ducting housing
structure and so as to respond to such bodily movement by tipping
to dump accumulated solids. The gas cleaning apparatus is disclosed
in connection with mobile surface sweeping equipment including a
pick-up head having means for regulating the flow of air from a
pressure chamber against the surface being cleaned and into a
suction chamber in the pick-up head.
Inventors: |
Williams; John K. (Waco,
TX) |
Assignee: |
Central Texas Iron Works, Inc.
(Waco, TX)
|
Family
ID: |
26889075 |
Appl.
No.: |
05/362,685 |
Filed: |
May 22, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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193514 |
Oct 28, 1971 |
3755851 |
Sep 4, 1973 |
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Current U.S.
Class: |
55/429; 15/340.1;
55/447 |
Current CPC
Class: |
A47L
11/40 (20130101); A47L 5/14 (20130101); A47L
11/24 (20130101); E01H 1/0863 (20130101) |
Current International
Class: |
A47L
5/14 (20060101); A47L 5/12 (20060101); A47L
9/10 (20060101); E01H 1/00 (20060101); E01H
1/08 (20060101); B01d 050/00 () |
Field of
Search: |
;55/337,429,432,459,447
;15/340 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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232,087 |
|
Jan 1961 |
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AU |
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474,627 |
|
Aug 1969 |
|
CH |
|
Primary Examiner: Nozick; Bernard
Attorney, Agent or Firm: Baldwin, Wight & Brown
Parent Case Text
This is a division of application Ser. No. 193,514 filed Oct. 28,
1971 now U.S. Pat. No. 3,755,851 issued Sept. 4, 1973.
Claims
I claim:
1. In apparatus for separating gas from particulate solid material
entrained therein, a support; a housing mounted on said support and
having one face thereof extending generally vertically; a blower in
said housing; first duct means in said housing extending through
said one housing face and to the blower intake; second duct means
in said housing extending through said one housing face and to a
source of gas with particulate solid material entrained therein;
means comprising a solids collection receptacle for separating gas
from particulate solid material entrained therein, said solids
collection receptacle having an open face; means mounting said
receptacle on said support normally with said open face thereof
covering said one face of said housing with both of said duct means
communicating through said one housing face with the interior of
said receptacle, whereby gas in said receptacle is withdrawn
therefrom through said first duct means and through said blower
intake with resultant drawing of gas and entrained solid material
through said second duct means into said receptacle to pass
therethrough with separation of solids from gas and passage of gas
out through said first duct means into said blower intake; and
operating means for moving said receptacle away from said one face
of said housing, said receptacle mounting means including position
control means responsive to movement of said receptacle away from
said one face of said housing for bodily elevating said receptacle
relatively to said housing and to said support to a position spaced
above said support, and for also tipping said receptacle to
discharge solid material from the elevated receptacle through said
receptacle open face.
2. Apparatus according to claim 1 in which said means mounting said
receptacle on said support comprises a relatively long link pivoted
at one end to said support at a point relatively remote from said
one face of said housing and at a relatively low level and pivoted
at its other end to said receptacle at a point relatively close to
said receptacle open face and at a relatively high level; and a
relatively short link extending above said relatively long link
when said receptacle is positioned, as normally, with its open face
covering said one face of said housing, said relatively short link
being pivoted at one end to said support remote from said one face
of said housing and being pivoted at its other end to said
receptacle close to said open face thereof.
3. Apparatus according to claim 1 in which said receptacle mounting
and position control means comprises two links both connected at
opposite ends to said support and to said receptacle
respectively.
4. Apparatus according to claim 3 in which said two links, said
support, and said receptacle together constitute a four bar
linkage.
5. Apparatus according to claim 3 in which said operating means
comprises a power operated extensible assembly pivoted at its
opposite ends respectively to said support and to an intermediate
point of one of said links.
6. In apparatus for separating gas from particulate solid material
entrained therein, a support; a housing mounted on said support and
having one face thereof extending generally vertically; a blower in
said housing; first duct means in said housing extending through
said one housing face and to the blower intake; second duct means
in said housing extending through said one housing face and to a
source of gas with particulate solid material entrained therein;
means comprising a solids collection receptacle for separating gas
from particulate solid material entrained therein, said solids
collection receptacle having an open face; means mounting said
receptacle on said support for bodily movement from a normal
position to a discharging position, said receptacle open face
facing towards and covering said one face of said housing with both
of said duct means communicating through said one housing face with
the interior of said receptacle when said receptacle is in its
normal position, whereby gas in said receptacle is withdrawn
therefrom through said first duct means and through said blower
intake with resultant drawing of gas and entrained solid material
through said second duct means into said receptacle to pass
therethrough with separation of solids from gas and passage of gas
out through said first duct means into said blower intake, said
receptacle open face being displaced from said one face of said
housing and facing away from said one face of said housing when
said receptacle is in its discharging position; and operating means
for moving said receptacle from said normal position thereof to
said discharging position thereof, said receptacle mounting means
including position control means responsive to movement of said
receptacle from said normal position thereof to said discharging
position thereof for tipping said receptacle to discharge solid
material therein through said receptacle open face.
7. Apparatus according to claim 6 in which said receptacle mounting
and position control means comprises a four bar linkage, itself
comprising said receptacle, said support, and two links each
connected to said receptacle and to said support respectively.
8. Apparatus according to claim 6 in which said means mounting said
receptacle on said support comprises a relatively long link pivoted
at one end to said support at a point relatively remote from said
one face of said housing and at a relatively low level and pivoted
at its other end to said receptacle at a point relatively close to
said receptacle open face and at a relatively high level; and a
relatively short link extending above said relatively long link
when said receptacle is positioned, as normally, with its open face
covering said one face of said housing, said relatively short link
being pivoted at one end to said support remote from said one face
of said housing and being pivoted at its other end to said
receptacle close to said open face thereof.
Description
This invention is illustrated in connection with apparatus for
separating gas from particulate solid matter entrained in a stream
of the gas. This apparatus provides improvements in previously
known separation apparatus in which particulate solid matter is
picked up in a stream of gas, e.g., air, and conducted in a
substantially closed recirculating air stream system to separating
means including a receptacle into which solid matter separated from
the air stream is deposited. Such recirculating systems are used,
for example, in connection with street or other surface cleaning
equipments in which the cleaning action is performed mainly if not
entirely by air stream action, as distinguished from by brushing
the surface mechanically. While such recirculating systems are
intended to be, and in practice essentially are, closed, it is
inevitable that some, although relatively very little, air is drawn
from outside the system into the suction side of the system which
thereby increases the total amount of air in the system. Since the
system is essentially of fixed volume, the drawing in of additional
air tends to increase the average pressure throughout the system.
This increase in pressure will cause some air with entrained dust
to be discharged from the high pressure side of the circulation
system through leaks in the ducting or collection receptacle or
from the pressure chamber of the pick-up head. Air leaking under
pressure carries with it entrained dust or other particles,
discharging of which to the atmosphere is naturally undesirable, in
fact in many situations, intolerable.
Gas and particulate solid matter separating apparatus as outlined
above is claimed in my co-pending parent application Ser. No.
193,514, now U.S. Pat. No. 3,755,851 dated Sept. 4, 1973.
An object of the invention is to provide means for mounting the
solids collection receptacle of a gas and particulate solids
material separation apparatus in such manner that the receptacle
may be moved bodily away from a blower and ducting housing included
in such apparatus and, as an incident to such bodily movement, will
be tipped to discharge collected solids.
Other objects of the invention will become apparent from a reading
of the following description of a preferred embodiment, the
appended claims, and the accompanying drawings, in which:
FIG. 1 is a somewhat schematic side elevational view of mobile
surface sweeping equipment comprising a truck and apparatus for
separating entrained solids from air supported thereon;
FIG. 2 is a top plan view of the equipment shown in FIG. 1;
FIG. 3 is a longitudinal vertical section on the line 3--3 of FIG.
2;
FIG. 4 is a vertical section on the line 4--4 of FIG. 2;
FIG. 5 is a vertical section on the line 5--5 of FIG. 2;
FIG. 6 is a horizontal section on the line 6--6 of FIG. 3;
FIG. 7 is an enlarged scale horizontal section on the line 7--7 of
FIG. 4, an air bleed-off valve being shown in position for bleeding
air from a main air circulatory system;
FIG. 8 is a view similar to FIG. 7, but showing the valve in a
different position, for reverse flow cleaning of a filter;
FIG. 9 is a perspective view, with parts broken away, showing the
inside of a housing with a blower and ducts and separator chamber
being illustrated;
FIG. 10 is an enlarged scale cross section of a pick-up head;
FIG. 11 is a fragmentary longitudinal section of the pick-up head
on the line 11--11 in FIG. 10, with parts broken away, and drawn on
a smaller scale than FIG. 10;
FIG. 12 is a perspective view of an angle plate member included in
the pick-up head construction; and
FIGS. 13A, 13B and 13C are diagrammatic elevational views showing
successive positions of a solids collection receptacle during a
dumping operation.
A representative embodiment of the invention is shown as being
mounted on a mobile truck or the like permitting the equipment to
be moved over a street or other surface to be cleaned. In general,
surface cleaning is effected by directing a blast of air against
the surface to entrain particulate solid matter in an airstream
which is then delivered to equipment for separating the solid
particulate matter from the airstream and for then returning the
air under pressure so as to recirculate continuously in the
cleaning of the surface. The equipment is shown as being mounted on
a wheeled truck T having a frame 1 for supporting the equipment for
picking up solid particles in the airstream and separating the
particles from the air. An operator's seat 2 and steering wheel 3
are shown conventionally. The truck T may be driven by any
conventional means.
Considering the surface cleaning and air and solids separating
equipment generally, a blower B receives its intake of air from a
solids collection receptacle SCR, thereby reducing the pressure in
the receptacle to a relatively negative pressure. The blower
delivers air under pressure through a duct 4 to a pressure chamber
PC in a hollow pick-up head structure PH, the construction of which
is described more particularly hereinafter. An air blast is
delivered from the pressure chamber PC downwardly against the
surface to be cleaned and thence to a suction chamber SC in the
pick-up head. Air with entrained particulate matter flows from the
suction chamber SC to the solids collection receptacle SCR through
a suction duct 5 and further ducting means to be described later.
The air with entrained solid matter entering the collection chamber
SCR is reversed in its flow in the receptacle so that some of the
solid matter drops out of the airstream into the bottom of the
receptacle. Air thus at least partially cleaned flows to the blower
intake via supplemental separating structure generally designated 6
in FIGS. 3, 6 and 9 and which will be further described
hereinafter. Air flows from the supplemental separating structure 6
to the blower intake, thus completing the circulation which is
repeated continuously over the same system route.
Considering the illustrative construction more particularly, a
housing generally designated 7 encloses the blower B and provides
ducting required for the air to flow over the recirculating path
generally described above. The housing 7, which is mounted on the
support 1, includes side walls 8 and 9, a front wall 10, a bottom
wall 11, and a top wall 12. The rear face of the housing 7 is open,
that is unwalled.
Mounted in the housing 7 are two vertical partitions 13 and 14
extending fore-and-aft between the front wall 10 and the open rear
face of the housing. Rotatably mounted in the space between the
partitions 13 and 14 is the blower impeller 15 driven through a
shaft 16 by an engine 17 and clutch 18 generally indicated in FIG.
2. As shown in FIGS. 4 and 9, a curved shroud 19 is mounted between
the partitions 13 and 14 so as partially to surround the impeller
15. Also, as shown in FIG. 4, are transition members 20 and 21
mounted between the partitions 13 and 14 and extending downwardly
from the shroud 19 to the pressure duct 4 leading to the pressure
chamber PC of the pick-up head PH. Air discharged peripherally by
the impeller 15 is thus delivered downwardly through the pressure
duct 4 to the pressure chamber PC.
The space 22 in the housing 7 between the housing side wall 9 and
the partition 14 serves as part of duct means communicating with
the suction duct 5 and suction chamber SC of the pick-up head PH,
the space 22 being open at the rear face of the housing 7.
As shown in FIGS. 2, 3, 6 and 9, the space between the partition 13
and the housing side wall 8 serves as a separation chamber 23 which
is useful for removing from air flowing to the blower any entrained
solid matter which was not deposited in the collection receptacle
SCR.
The chamber 23 is open at its rear to the receptacle SCR and
communicates with the blower intake through an inlet opening 24 in
the partition 13. Mounted in the separation chamber 23 is a curved
partition 25 with a rearward-downward extension 26 projecting to
the rear of the housing 7 as clearly shown in FIG. 3. The curved
partition 25 follows generally the curvature of a curved part 10a
of the housing front wall 10.
Mounted in the separation chamber 23 is a curved baffle 27
generally following the curvature of the partition 25. The upper
edge 28 of the baffle 27 is spaced substantially below the top 12
of the housing 7, whereas the lower or opposite edge 29 of the
baffle 27 is spaced from but is relatively very close to the
mergence of the curved partition 25 with its extension 26. The
relatively large spacing of the baffle edge 28 from the top 12 of
the housing provides for free flow of air from the collection
receptacle SCR tangentially into the separation chamber 23 so as to
create a swirling or vortex action which centrifugally concentrates
any remaining solid particles out against the wall 10a, 25 of the
separation chamber 23. The concentrated solids are skimmed out
through a skimmer slit 30 defined by the lower edge 29 of the
curved baffle 27 and the adjacent part of the partition 25.
The solids collection receptacle SCR is mounted on the support 1 by
means permitting it to be raised and dumped as later to be
described. At this point it is sufficient to explain the
construction of the collection receptacle SCR as it is related to
its functioning as part of the circulating system for separating
solids from air. The receptacle includes a top wall 31, side walls
32 and 33, a rear wall 34, and an obtusely angled bottom wall 35.
The front face of the receptacle is open, that is unwalled. When
the receptacle is in operative position, its open front face
permits free communication between the receptacle and the duct
space 22 in the housing 7 between the side wall 9 and the partition
14 of the housing. The open front face of the receptacle also
places the receptacle into communication with the separator space
23 included between the housing partition 13 and housing side wall
8 as described above. As shown in FIG. 6, the housing 7 is provided
with a laterally offset wall extension 36 which closes the open
front face of the collection receptacle SCR beyond the housing wall
9.
As shown in FIGS. 3, 6 and 9, the collection receptacle SCR is
fitted with a screen partition 37 extending fore-and-aft and
generally in alignment with the housing partition 13 and dividing
the receptacle into two sections. Air with entrained solid matter
enters the receptacle SCR from the duct space 22 and flows through
the screen 37 before being returned to the blower intake 24 by way
of the supplemental separation chamber 23. The screen 37 is useful
for intercepting a considerable portion of the entrained solid
matter before the circulating air is returned to the blower.
One form of pick-up head suitable for use in connection with an air
cleaning apparatus of the kind described above is shown in FIGS. 10
and 11, although other pick-up head constructions may be used. The
pick-up head PH as shown in FIGS. 10 and 11 includes a stepped top
plate wall 38 provided with longitudinal flanges 39 and 40, and end
panels 41. A horizontal wall 42 is welded or otherwise secured to
the inside of the flange 39 spaced below the top wall 38 and
extends toward the longitudinal center of the pick-up head PH. The
horizontal wall 42 mounts two flexible or yieldable U-shaped
members 43 formed with spaced downwardly extending aprons or
curtains 44. The members 43 are secured to the wall 42 by clamping
strips 45 and bolts 46.
Underneath the opposite edge of the pick-up head PH, that is
adjacent to the flange 40, is mounted another flexible member 47
generally U-shaped in cross section and comprising aprons or
curtains 48. A channel-shaped strip 49 and bolts 50 clamp the
member 47 to the bottom face of the top wall 38.
The end panels 41 are provided with skids 41a which rest upon the
surface being cleaned and support the pick-up head PH. The curtains
44 and 48 and the end panels 41 together enclose a working air
space including both the pressure chamber PC and the suction
chamber SC. The curtains assist in supporting the pick-up head, but
the curtains 48 are flexible enough to yield upwardly and admit
cans and other objects into the pick-up head working space. As
shown in FIGS. 1 and 6, the pick-up head PH is towed along in the
direction of cleaning movement progress by draw bars 51 connected
at their rear ends to the pick-up head PH and connected at their
front ends to the truck frame 1.
Extending generally centrally and longitudinally inside the pick-up
head and transversely to the direction of cleaning movement
progress is an inclined partition generally designated 52 which
separates the suction chamber SC from the pressure chamber PC. The
partition comprises a plate 53 secured to the inner face of the
step-down part 38a of the top plate wall 38, and an inclined flange
42a extending along the front edge of the horizontal plate 42. The
flange 42a is parallel to and spaced from the lower portion of the
plate 53 so as to provide an elongated orifice slit 54 for
discharging blast air from the pressure chamber PC against the
surface being cleaned at a downward-forward inclination and thence
into the suction chamber SC. The spacing of the lower part of the
plate 53 from the flange 42a and hence the width of the slit 54 are
fixed by two spacers 55 at the respective ends of the orifice slit
between the plate 53 and the flange 42a, and two intermediate
spacers 56 between the plate 53 and the flange 42a. The end spacers
55 have downwardly-inwardly sloping edges as shown in FIG. 11.
These edges direct blast air emerging from the slit orifice
inwardly and away from the respectively adjacent ends of the
suction chamber toward the longitudinal center of the latter.
At each end of the suction chamber SC is an angle plate member 57
secured to the inside of the adjacent end panel 41. One angle plate
member 57 is shown in FIG. 12 as having its vertical web 57a
secured to the inner face of the one end panel 41 and having its
horizontal web 57b extending inwardly from that panel into the
suction chamber. The other angle plate member 57 (not shown) is
similarly mounted on the other end panel 41. The horizontal webs
57b of the members 57 are chamfered 45.degree. at 57c as shown also
in FIG. 12. The plate members 57 divert blast air from ends of the
suction chamber toward its center and thus prevent blow-out of
blast air at the ends of the suction chamber.
In operation, air delivered under pressure by the blower B flows
downwardly through the pressure duct 4 into the pressure chamber PC
of the pick-up head. Air under pressure in the pressure chamber
flows at high velocity in the manner of a blast through the slit
orifice 54 to impinge upon the surface being cleaned at an angle so
as to dislodge particles from the surface and disperse them in the
suction chamber SC. Air with entrained particulate solid material
is then drawn from the suction chamber up through the suction duct
5 into the duct space 22 in the housing 7 and thence into the
collection receptacle SCR between the receptacle side wall 33 and
the screen 37, a considerable portion of the entrained solid
material descending to the bottom of that part of the receptacle by
gravity. The screen 37 intercepts non-descended solid particles
from the airstream as it passes into the part of the collection
receptacle between the screen 37 and the side wall 32 of the
receptacle. The airstream flows from the latter part of the
receptacle into the supplemental separation chamber 23 and thence
through the blower intake 24, thus completing the recirculation
flow path. Very fine solid particles remaining in the airstream
flowing from the receptacle SCR into the supplemental separation
chamber 23 are largely removed by the centrifugal action resulting
in skimming off of fine solid particles through the skimmer slit 30
and returning of those particles downwardly along the partition
extension 26 to the collection receptacle.
Although the recirculation system described above is essentially a
closed system, as a practical matter some air in addition to that
being circulated inevitably is drawn into the system where under
suction conditions, principally at the ground/curtain interface.
Air may also be drawn in in lesser degree through any leaks in
imperfectly sealed joints in the housing 7 defining the suction
duct space 22, and where the collection receptacle SCR fits against
the housing 7 without perfect sealing. Whatever additional air is
drawn into the closed system tends to raise the average system
pressure above atmospheric pressure. This means that there must be
some discharge of air from the system to compensate for that drawn
in. Emitting air through leakage or say under the curtains 44
adjoining the pressure chamber PC would result in blowing dirty air
into the atmosphere which would obviously be undesirable and which
would result in sacrificing advantages otherwise obtainable by the
use of the closed circulating system.
The construction illustrated and described above has provision for
discharging or bleeding off air in an amount approximately equal to
that drawn in incidentally so as to maintain the average system
pressure at a desired low level. The air discharged or bled off is
delivered to the atmosphere without discharging significant amounts
of dust or other particles freely to the atmosphere. This is
accomplished by by-passing or bleeding some of the circulating air,
which may contain some entrained solid particles, through a filter
by means of equipment now to be described.
A by-pass or pressure relief plenum structure generally designated
64 is mounted on the housing 7 adjacent the top of the curved part
10a of the housing front wall 10. The plenum structure 64 includes
a top wall 65, a bottom wall 66, a curved end wall 67, an outer
side wall 68, and an inner side wall 69. The plenum bottom wall 66
abuts the curved part 10a of the housing front wall 10 as shown in
FIGS. 4, 5 and 9. The side walls 68 and 69 conform at their rear
ends to the curvature of and they abut the curved wall part 10a of
the housing front wall. The plenum structure 64 includes an
additional wall 70 which is spaced inwardly from the wall 69 as
shown in FIGS. 7 and 8 so as to provide a flow passage 71 leading
tangentially into the round part of the plenum.
A pressure relief or by-pass opening 72 is formed in the blower
casing adjacent the juncture of the housing front wall 10 and the
top wall 12 as shown in FIGS. 2, 4 and 9. The pressure relief
opening 72 communicates with the flow passage 71 of the plenum
64.
A suction port 73 is formed in the housing 7 adjacent the
convergence of the front wall 10a with the housing top wall 12 so
as to communicate with the ducting space 22 previously described as
being between the housing wall 9 and the partition 14. The port 73
is also adapted to communicate with the plenum 64 at a zone spaced
circumferentially from the tangential reception of air entering the
plenum from the passage 71.
At the center of the plenum 64 is a gas bleed outlet extending
through a spigot 74 on which is mounted the open end part of a
filter bag 75 of foraminous material.
A segment-shaped by-pass control valve 76 is pivoted at 77 at the
center of curvature of the plenum wall 67 and is operable by a
handle 78 located above the plenum 64 as shown in FIGS. 2 and 3 so
as to be movable to two positions as shown respectively in FIGS. 7
and 8.
Normally, that is during most periods of operation, the valve 76
will be positioned as shown in FIG. 7 so that there is free opening
for air with entrained dust to move from the relief opening 72 and
passage 71 into the plenum circular part tangentially. In this
position of the valve 76, an edge 76a of the valve is closely
adjacent to the plenum wall 68 so as to prevent free communication
between the plenum and the port 73, but leaves a narrow skimmer
slit between the valve edge 76a and the plenum wall 68. The slit
provides for controlled restricted communication of the port 73
with the plenum 64 at a zone spaced circumferentially approximately
180.degree. from the tangential reception of by-passed air by the
plenum. Some of the dirt laden air flowing circularly in the plenum
will be relieved of its dust by centrifugal force concentrating the
dust particles in the outer part of the plenum from which they are
passed through the skimmer slit at the valve edge 76a with a small
amount of air. The air and dust passing through the skimmer slit
are returned to the system through the port 73, suction duct space
22, and collection receptacle SCR. However, the major part of the
air received in the plenum 64 from the relief opening 72 flows to
the plenum center and out through the bleed outlet 74 into the
filter bag 75. The bag traps and retains practically all of the
entrained dust while the bled-off air passes out through the bag to
the atmosphere without harmful and unpleasant results.
After operating for some time with the valve 76 in the position
shown in FIG. 7 with bleeding off of surplus air as described
above, the filter bag 75 normally will accumulate a considerable
amount of dust or other pqrticles which, if not removed, would
reduce the efficiency of the filter. Accordingly, it is desirable
to provide for cleaning the filter. Of course, this could be done
by removing the bag 76 and replacing it with a clean bag, but this
would involve additional trouble and expense and extra equipment.
The present construction provides for cleaning the filter bag 75 by
the simple expedient of moving the valve 76 to the position shown
in FIG. 8 in which the valve edge part 76b opposite the edge 76a
blocks off the passage 71 and the valve edge part 76a is widely
spaced from the plenum wall 68 so as to place the curved part of
the plenum and also the interior of the filter bag 75 in
substantially unrestricted communication with the port 73 and hence
with the suction duct space 22 and receptacle SCR. The inside of
the bag 75 is thereby subjected to suction which causes the bag to
give up dust or other particles residing in the bag. Removal of the
particles from the bag is enhanced by flexing of the bag resulting
from reversal of flow of air into the bag from the atmosphere, as
distinguished from the normal flow outwardly through the bag into
the atmosphere. The air drawn into the bag 75 from the atmosphere
entrains the dust dislodged from the bag walls and carries it by
suction flow through the port 73 and duct space 22 into the
receptacle SCR.
The setting of the valve 76 in the FIG. 8 position for cleaning the
filter bag is used only periodically and for relatively short
periods as compared to the operation under the normal conditions
when the valve is positioned as shown in FIG. 7. The frequency of
reverse cleaning the filter by positioning the valve as shown in
FIG. 8 may be reduced by connecting the bottom of the filter bag to
the suction side of the recirculatory system. In the form shown,
the bottom of the bag 75 is connected to a tube 75a communicating
with the suction chamber SC in the pick-up head PH. Dust or solids
in the filter bag which do not adhere to the bag side walls but
drop to the bottom of the bag are thus returned directly to the
suction side of the system while the valve 76 is in its normal
position as shown in FIG. 7. Suction removal of solid particles
from the bottom of the bag 75 is improved by provision of a disk
cover 75b on the tube 75a formed with a restricted air passage hole
75c. Air drawn by suction from the bag 75 into the suction chamber
SC must flow at a high velocity through the hole 75c so as
efficiently to entrain particles and carry them into the tube 75a
and thence to the suction chamber SC.
The solids collection receptacle SCR is mounted so as to be
supported on the truck frame 1 and to be moved from its normal
position shown in FIG. 1 bodily away from the housing 7 and
simultaneously to be tipped so as to discharge material collected
in the receptacle to the rear and through the open face 78 of the
receptacle. In the normal position of the receptacle, its open
front face 78 communicates directly with the suction duct space 22
and with the separation chamber 23 in the housing 7. When the
receptacle is moved bodily away from the housing 7 and is tipped,
the housing contents are dumped or discharged through the open face
78 of the receptacle, thus dispensing with the necessity of
providing a separate clean-out door or gate.
As shown in FIG. 1, control means for tipping the receptacle when
it is moved away from the housing includes a relatively long link
79 pivoted at 80 to a bracket 81 on the support 1, and pivoted at
82 to the receptacle SCR relatively close to the receptacle open
face 78 and near the top of the receptacle.
A relatively short link 83 extending above the link 79 is pivoted
at 86 to the receptacle side wall 32 close to the receptacle top
wall 31. The links 79 and 83 together with the support 1 and the
receptacle SCR constitute a four-bar linkage.
Means for operating the control linkage includes a power operable
extensible assembly generally designated 87 and in the present
instance illustrated as an assembly of a cylinder 88 and piston rod
89 operable under fluid pressure from a source, not shown. The
cylinder 88 is pivoted at 90 on the support 1, and the piston rod
is pivoted at 91 to an intermediate part of the link 79. Fluid
pressure extension of the piston rod 89 operates through the links
79 and 83 and other components of the four-bar linkage to move the
receptacle SCR from the normal position shown in FIG. 1
successively through the positions shown in FIGS. 13A, 13B and 13C,
thus moving the receptacle SCR bodily away from the housing 7. As
illustrated in FIGS. 13A, 13B and 13C, the control linkage responds
to movement of the receptacle away from the housing by bodily
elevating the receptacle relatively to the housing 7 and to the
support 1 to a position spaced above the support, and by also
tipping the receptacle so far as to dump the contents through the
same open face 78 as was positioned against the open face of the
housing 7 during normal operation. The linkage and operating means
located adjacent the side 32 of the collection receptacle SCR have
been described. For balancing forces, a similar mechanism is
provided at the side 33 of the receptacle.
When the receptacle SCR is in its normal position with its open
front face adjacent the generally vertically extending open rear
face of the housing 7, flanges 92 surrounding the front face of the
receptacle abut sealing gaskets 93 which surround the rear face of
the housing 7. This provides a sufficiently good seal to prevent
inward leakage of more air than can be compensated for by the
bleeding off of air through the filter 75. The screen 37 is secured
to the receptacle SCR walls 31, 34 and 35 by strips 94. As shown in
FIGS. 3 and 6, two flanged strips 95 extend along the front edge of
the screen 37. When the receptacle is in its normal position as
shown in FIGS. 1, 3 and 6, the flanges of the strips 95 fit over
and embrace a rearward extension 13a of the housing partition 13.
In this manner, the front edge of the screen 37 is supported
against lateral deflection, for example in the event of piling of
dust and even heavier particles against one side of the screen.
Although the invention has been described in its application to air
blast surface cleaning, it will be understood that apparatus
according to the invention may be used for separating particulate
solid material from air or other gas generally, and not only in
connection with street or other surface cleaning operations. The
construction illustrated and described embodies the invention in a
preferred form, but it is intended that the disclosure be
illustrative rather than definitive, the invention being defined in
the claims.
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