US3893262A

US3893262A - Particulate transfer control device

Info

Publication number: US3893262A
Application number: US470227A
Authority: US
Inventors: James A Giese
Original assignee: Fruehauf Corp
Current assignee: Fruehauf Corp
Priority date: 1974-05-15
Filing date: 1974-05-15
Publication date: 1975-07-08
Anticipated expiration: 1992-07-08
Also published as: DK212175A; ZA752546B; DE2521670C2; BE829003A; CA1015006A; GB1499594A; JPS50146993A; NO751714L; SE7505528L; JPS5820756B2; BR7502977A; FR2271149A1; NL7505613A; ES437701A1; DE2521670A1

Abstract

The invention pertains to control means for apparatus for pneumatic transfer of a particulate material of the type having an air flow-way intersected by a particulate flow-way. The control means includes respective closure means for the air flowway and particulate flow-way and a fluid-actuated sequencing mechanism for sequentially operating the closure means. When both closure means are open, the sequencing mechanism may be operated by a single control to cause closing of the particulate flow-way first, followed by closing of the air flow-way.

Description

United States Patent Giese 1 July 8, 1975 [54] PARTICULATE TRANSFER CONTROL 3.54:1,444 [2/1970 Mehta 51/12 X 3,768,210 10/1973 Johnson 51/12 [75] Inventor: James A. Giese, Houston, Tex

[73] Assignee: Fruehauf Corporation, Detroit, Primary EXami'1er'D0na|d Kelly Mi h Attorney, Agent, or Firm-Br0wning & Bushman [22] Filed: May 15, 1974 I N 47 227 [57] ABSTRACT [2 App The invention pertains to control means for apparatus for pneumatic transfer of a particulate material of the [52] U.S. Cl 51/12; 51/12 t pe having an air flow-way intersected by a particu- [51] Int. Cl. 824C 7/00 late flow-way. The control means includes respective [58] Field of Search 51/8 R, 12 closure means for the air flow-way and particulate flow-way and a fluid-actuated sequencing mechanism [56] References Cited for sequentially operating the closure means. When UNITED STATES PATENTS both closure means are open. the sequencing mecha- 2 521 931 9/1950 Mead 51 12 may be operamd by a Single Comm cause 3O7OI924 [/1963 Hastrui) I I I I I M 51/12 X closing of the particulate flow-way first, followed by 3,089.285 5/1963 Moore 51 12 x closing of the air y- 3,l39,705 7/1964 Histed 51/12 X 3.201.901 8/1965 Pauli 51/12 7 Clam, 5 Drawmg F'gures 1 PARTICULATE TRANSFER CONTROL DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention pertains to apparatus for pneumatic transfer of particulate materials and in particular to abrasive blasting apparatus. Such apparatus is commonly called sand blasting apparatus because sand is one of the most popular abrasives used. Such equipment generally comprises a heavy duty hose and nozzle. The hose is connected to the outlet of an air directing member having an air flow-way therethrough. Compressed air is supplied to the air flow-way and flows through the flow-way, hose, and nozzle at a rapid rate and under high pressure. The apparatus also includes an abrasive container adjoining a particulate directing member which has a particulate flow-way therethrough communicating with the air flow-way. Sand or other particulate abrasive is deposited in the air flow-way through the particulate flow-way in the path of the compressed air. The air thus picks up the sand and carries it along the hose and out through the nozzle on the end of the hose with a considerable velocity. The operator uses the nozzle to direct the sand against a target. The air flow-way and particulate flow-way usually form a generally T-shaped flow-way system.

One of the problems associated with this type of equipment is that, when the air flow is cut off to temporarily stop the operation, the particulate material continues to flow into the air flow-way and accumulate there. Then when the air flow is resumed the flow-way is partially or totally blocked by the particulate. In sand blasting equipment, for example, this can cause a very strong burst of material from the hose accompanied by a whipping action of the hose. Not only is the blast itself dangerous, but the whipping of the hose can injure the operator. The accumulation of sand in the air flow-way can also cause damage to the blasting equipment itself, particularly if the air flow-way becomes so thoroughly blocked that air can not flow at all. Similar conditions can occur upon start-up of the equipment if the sand begins to flow before the air has begun to flow at a sufficient volume, and velocity.

2. Description of the Prior Art Several different systems have been devised to combat the problems described above. In particular. U.S. Pat. No. 3,148,484 to Meek discloses a sand blasting device in which the sand is prevented from flowing into the hose until the air has reached a certain pressure. This device, however, is relatively complicated mechanically. Some of its moving parts are subject to interference by sand. Furthermore, it fails to adequately solve the problem of continued sand flow after shutdown of the air flow.

Another approach to the problem is to provide separate controls for the air and sand. Still another solution is proposed by U.S. Pat. No. 3,139,705 to Histed, which shows an electronic device for automatically shutting off the flow of sand if the air flow is accidentally stopped.

SUMMARY OF THE INVENTION The present invention offers a new solution to this problem which is simpler and more convenient, and solves the problem in a more complete and satisfactory manner. The control means of the invention includes respective closure means for the air flow-way and the particulate flow-way. A sequencing mechanism having control fluid passageways therein is operatively connected to the closure means. A single switch or the like is provided for selectively causing a control fluid to flow in a desired flow pattern in the control fluid passageways.

In its most basic form, the invention provides for the selection of a first flow pattern to be used when the closure means are both open and it is desired to close them so as to shut down the equipment. When the control fluid is caused to flow in this first pattern, the sequencing mechanism operates to cause the closing of the particulate flow-way first, followed by closing of the air flow-way, by their respective closure means. It is therefore an object of the invention to provide for closing of the particulate flow-way first, followed by closing of the air flow-way, upon shutdown.

In a preferred embodiment, the invention provides for selection of a second flow pattern to be used when both closure means are closed and it is desired to open them to start up the equipment. When the control fluid flows in the second pattern, the sequencing mechanism causes opening of the air flow-way first followed by opening of the particulate flow-way. Therefore another object of the invention is to provide for opening of the air flow-way first followed by opening of the particulate flow-way upon start-up of the apparatus.

Yet another object of the invention is to provide control means by which both the air flow-way and the particulate flow-way can be opened or closed in a desired sequence by operation of a single switch or the like.

In the preferred embodiment, the sequencing mechanism is devised, by virtue of the relative sizes of the passageways therin, so as to control the relative speed with which the two closure means are opened and closed. In particular, at shut-down the closing of the air flow-way proceeds at a slower rate than that of the particulate flow-way, while at start-up the opening of the particulate flow-way proceeds at a slower rate than that of the air flow-way. Thus a further object of the invention is to provide control means having a sequencing mechanism capable of controlling the relative speed of operation of the two closure means.

Each of the closure means preferably comprises a movable operator such as a diaphragm or piston operative to open the flow-way in response to greater pressure on one side thereof and to close the flow-way in response to greater pressure on the other side. Appropriate ones of the control fluid passageways in the sequencing mechanism are directly connected to areas on appropriate sides of the movable operators so that the control fluid can enter and leave these areas to operate the closure means. Thus still another object of the invention is to provide control means wherein the control fluid of the sequencing mechanism operates movable operators which in turn cause opening and closing of the flow-away.

Other objects and advantages of the invention will be made apparent by the following detailed description of the preferred embodiments and by the drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a pneumatic particulate transfer apparatus incorporating the control means of the invention.

FIG. 2 is a view partly in section and partly in elevation taken along the lines 2-2 of FIG. I.

FIG. 3 is a sectional view of the sequencing mechanism taken along the lines 33 of FIG. 1.

FIG. 4 is a detailed sectional view of a portion of the particulate flow-way closure means in closed position.

FIG. 5 is a diagramatic illustration of the apparatus of FIGS. 1-3 as used with sand blasting equipment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, there is shown a pneumatic transfer apparatus designed for use with sand blasting equipment and incorporating the control means of the invention. It should be understood, however, that similar transfer apparatus, including the control means of the invention, could be used with other types of equipment in which a particulate material is picked up and moved along a flow-way by a stream of air or other fluid.

The apparatus 10 has an air directing portion, comprising

fittings

30 and 40, and having air flow-way 12 extending therethrough. A particulate flow-way 14 extends through a particulate directing portion comprising slider member 54, resilient annulus 46, and fitting 40, and intersects the air flowway 12 at a right angle. A source of compressed air 16 is connected to the inlet [8 of the air flow-way 12 by means of a hose 20. Another hose 22 is connected to the outlet 24 of the air flow-way 12. A nozzle 26 is provided on the other end of hose 22. In use the operator uses this nozzle 26 to direct the blasting sand onto a target.

The air flow-way 12 extends in a generally horizontal direction from its inlet 18 in fitting 30 to a first vertically directed section 28. A diaphragm housing, comprising upper and

lower members

32 and 34 respectively, is connected to the fitting 30 so that a bore 36 in the lower member 34 registers with the vertically directed section 28 of the air flow-way 12. The bore 36, the diaphragm area 38 defined by the diaphragm housing, and bores 39 in the lower housing member 34 define a continuation of the air flow-way, bores 39 registering with a second vertically directed section 40 of the air flow-way 12 in the fitting 30. The remainder of the air flow-way is substantially horizontal, extending through the fitting 30 and the adjoining pipe-like fitting 40 to the outlet 24 in the fitting 40.

A diaphragm 42 clamped between the upper and lower

diaphragm housing members

32 and 34 is operative, responsive to the distribution of pressure in the areas adjacent its upper and lower sides to open and close the air flow-way l2 upstream of the particulate flow-way 14 by opening and closing the bore 36. Thus it serves as an air flow-way closure operator. The diaphragm 42 is biased downwardly by a compression spring 44 in the upper housing member 32 so that if the pressure in area 38 above the diaphragm is greater than or equal to the pressure in bore 36, the air flow-way 12 is closed. If the pressure in bore 36 exceeds that in area 38, the diaphragm will move upwardly opening the air flow-way as shown in FIG. 2.

The particulate flow-way 14 has three sections. The first of these, bore 48, passes through the fitting 40 to intersect the air flow-way 12. The second section 50 of the particulate passageway passes through an annulus 46 of resilient material held in an annular ridge 52 extending from the outer part of fitting 40 concentric with bore 48. The third section 60 of the particulate passageway extends through slider member 54 which has an annular end 56 which abuts one axial edge of the resilient annulus 46. The other edge of annulus 46 rests on the portion 58 of the outer surface of the fitting 40 which lies between the bore 48 and the ridge 52. The annular end 56 of the slider member 54 is of sufficiently small outer diameter to fit within the ridge 52 when the end 56 bears down against the resilient annulus 46. Annulus 46 is bevelled as 45 and 47 to prevent end 56 and ridge 52 from cutting into the elastomer.

The slider member 54 has a piston 60 extending radially therefrom which serves as a particulate flow-way closure operator. An open-ended casing 62 surrounds the piston 60 and a portion of the remainder of slider member 54 to form a snug slideway for the piston 60 and the adjacent portion of the slider member 54. The inner surface of the casing 62 is sealed against the portion 70 of the slider member 54 by

seals

72, 74, 76 to provide a closed area 66 on one side of the piston 60. The casing 62 is connected to the fitting 40 by studs 64. When pressure is applied to the area 66 above the piston in excess of the pressure, usually atmospheric, below the piston, the slider member 54 is moved downwardly. The end 56 bears against the resilient annulus 46 axially compressing it and forcing the resilient material to flow radially inwardly closing the section 50 of the particulate passageway through the resilient annulus 46 as shown in FIG. 4. An annular recess 68 is provided in the lower side of piston 60 to receive the ridge 52 when piston 60 moves down. When the area 66 is vented, the resilient material tends to resume its normal shape forcing the slider member 54 upwardly and allowing opening of the particulate passageway.

The control means of the present invention also comprises a sequencing mechanism having a network of control fluid passageways therein. The sequencing mechanism operates by means of a control fluid, preferably air from source 16, flowing through the control fluid passageways in given patterns.

The sequencing mechanism includes an upstanding part 78 of the upper member 32 of the diaphragm housing, a line 80 by which the sequencing mechanism can be connected to a source of control fluid, a valve 82 in the line 80, and a line 84 which actually serves as an extension of one of the passageways in part 78 by which it is connected to the closed area 66 above piston 60.

Referring now to FIG. 3, it will be seen that the upstanding part 78 has a main control fluid passageway therein comprising

bores

86 and 88 and small branch bore 98. Bore 86 is formed by boring through portion 78 and then plugging the ends of the bore. Bore 88 extends inwardly from the top of portion 78 to intersect bore 86 and the opening of bore 88 serves as an inlet for the main control fluid passageway. Line 80 is connected to the opening of bore 88. An air closure passageway 90 connects the main control fluid passageway with the area 38 above the diaphragm. A one way valve 92 in the air closure passageway 90 allows control fluid to flow therethrough from area 38 to the main control fluid passageway but not in the opposite direction. A bleed hole 94 of substantially smaller diameter than the air closure passageway 90 also connects the main control fluid passageway with area 38.

A particulate closure passageway comprising bore and line 84 connects the main control fluid passageway to the area 66 above the piston 60. One way valve 96 is disposed in the particulate closure passageway so as to allow control fluid to flow therethrough from area 66 to the main control fluid passageway but not in the opposite direction. A bleed hole 102 of substantially smaller diameter than the particulate closure passageway connects the main control fluid passageway to bore 100 of the particulate closure passageway and thus to the area 66.

A two way valve 82 is disposed at a convenient location in line 80 between part 78 and the source of control fluid. Valve 82 comprises a hollow valve body 106 with a valve element 104 is disposed therein and rotatable in the valve body 106 by means of a handle 114. Valve body 106 has three spaced apart radial bores 108, 110, and 116 therein. The

bores

110 and 116 are connected by suitable connections to the respective upstream and downstream parts of line 80. Bore 108 is open to atmosphere. The valve element 104 has a bent passageway 112 therethrough. in the position shown in solid lines in FIG. 2 the valve element 104 is turned so that the ends of passageway 112 are aligned respectively with

bores

108 and 116 while bore 110 is blocked by the solid portion of the valve element 104. By turning the handle 114 the valve element 104 can be rotated to place passageway 112 in the position shown in dotted lines in FIG. 2 so that the ends of passageway 112 are respectively aligned with

bores

116 and 110.

As shown in FIG. 2, both the air flow-way and the particulate flow-way are opened by their closure means. In order to close the closure means and thus shut down the apparatus the valve element 104 would be turned to the position shown in dotted lines in FIG. 2 opening line 80. Pressurized control fluid would then flow through the control fluid passageways in its first flow pattern. Thus it would first flow into the main

control fluid passageway

88, 86. The control fluid would flow freely through particulate closure passageway 98, l00, 84 past one-way valve 96 and into the area 66 above the piston 60. Piston 60 would move down closing the particulate flow-way relatively quickly. Meanwhile, the flow of control fluid into the air closure passageway 90 would be blocked by the one-way valve 92. The control fluid would slowly bleed into the area 38 above the diaphragm bleed hole 94. Area 38 would gradually become pressurized, slowly pushing the diaphragm down to close the air flow-way after closing of the particular flow-way. Thus the sequencing mechanism not only controls the order in which the two flowways are closed, but also the relative speed with which they are closed. It will also be appreciated that the machine operator would accomplish this sequencing by a single movement of one switch, namely the valve handle 114.

In order to re-open the flow-ways and start up the equipment, the valve handle 114 would be turned to place the valve element 104 once again in the position shown in solid lines in FIG. 2. This causes the control fluid to flow in a second flow pattern in the control fluid passageways. The solid line position of valve element 104 vents the upstanding part 78 to atmosphere so that the pressurized control fluid in

areas

38 and 66 tends to begin flowing out of these areas. The fluid in area 38 flows freely through air closure passageway 90 past one-way valve 92, through bore 88, line 80, and valve 82 to atmosphere. This quickly relieves the pressure in area 38. The pressure of the air in bore 36 and the upstream part of air flow-way l2 pushes the diaphragm 42 up so that the air flow-way 12 is quickly opened and air begins to flow therethrough. Meanwhile the flow of control fluid from area 66 through particulate closure passageway has been blocked by oneway valve 96. Thus the control fluid must bleed slowly through bleed hole 102 from the particulate closure passageway 100 to the bore 86 and thence to atmosphere. As the pressure in area 66 is thus gradually relieved, the resilient annulus 46 assumes its uncompressed shape slowly pushing the slider member 54 up and opening the particulate flow-way 14 after air has begun to flow through air flow-way 12. Once again both the order and relative speed of operation of the two closure means are controlled by the sequencing mechanism and this is accomplished by a single adjustment of valve handle 114 by the operator.

As mentioned above, the control means of the invention is particularly advantageous and convenient since its control fluid can be compressed air supplied by tapping the source of air to the air flow-way.

It will be appreciated that many modifications of the embodiment described above can be made without departing from the invention, the scope of which is limited only by the appended claims.

I claim:

1. A control means for use with apparatus for pneumatic transfer of a particulate material of the type including an air directing portion having an air flow-way therethrough, means supplying said air flow-way with compressed air, and a particulate directing portion having a particulate flow-way therethrough communicating with said air flow-way to deposit said particulate material in said air flow-way, said control means comprising:

air flow-way closure means operative to open and close said air flow-way;

particulate flow-way closure means operative to open and close said particulate flow-way; and

a sequencing mechanism operatively connected to said air flow-way closure means and to said particulate flow-way closure means and having control fluid passageways and including means responsive to a first flow pattern of said control fluid in said control fluid passageways, when said air flow-way closure means and said particulate flow-way closure means are both open, to cause closing of said particulate flow-way by said particulate flow-way closure means first. followed by closing of said air flow-way by said air flow-way closure means;

and means for selectively causing said control fluid to flow in said first pattern.

2. Control means according to claim 1 wherein said sequencing mechanism includes means responsive to a second flow pattern of said control fluid in said control fluid passageways when said closure means are both closed to cause opening of said air flow-way by said air flow-way closure means first, followed by opening of said particulate flow-way by said particulate flow-way closure means, said control means further comprising means for selectively causing said control fluid to flow in said second pattern.

3. Control means according to claim 2 wherein said means responsive to said first flow pattern is further operative to cause the closing of said air flow-way to proceed at a slower rate than the closing of said particulate flow-way and wherein said means responsive to said second flow pattern is further operative to cause the opening of said particulate flow-way to proceed at a slower rate than the opening of said air flow-way.

4. Control means according to claim 1 wherein said air flow-way closure means includes an air flow-way closure operator having first and second sides and movable in response to pressure on said first side thereof greater than pressure on the second side thereof to cause closing of said air flow-way;

wherein said particulate flow-way closure means includes a particulate flow-way closure operator having first and second sides and movable in response to pressure on said first side thereof greater than pressure on said second side thereof to cause closing of said particulate;

and wherein said sequencing mechanism has therein:

a main control fluid passageway, an inlet for delivering said control fluid to said main control fluid passageway, an air closure passageway connecting said main control fluid passageway with a first area on said first side of said air flow-way closure operator, a one-way valve in said air closure passageway operative by pressure in said main control fluid passageway greater than the pressure in said first area to close said air closure passageway, a first bleed hole of smaller diameter than said main control fluid passageway connecting said main control fluid passageway to said first area, and a particulate closure passageway of greater diameter than said bleed hole connecting said main control fluid passageway with a second area on said one side of said particulate passageway closure operator.

5. Control means according to claim 4 wherein said sequencing mechanism further includes a one-way valve in said particulate closure passageway operative by pressure in said second area greater than the pres sure in said main control fluid passageway to close said particulate closure passageway, and has therein a second bleed hole of smaller diameter than said main control fluid passageway connecting said particulate closure passageway to said main control fluid passageway.

6. Control means according to claim 1 wherein said control fluid is comprised of compressed air from said supplying means, and wherein said control means includes means for selectively injecting compressed air from said supplying means into the control fluid passageways of said sequencing mechanism.

7. Control means according to claim 1 wherein said pneumatic transfer apparatus is abrasive blasting apparatus and said particulate material is abrasive.

Claims

1. A control means for use with apparatus for pneumatic transfer of a particulate material of the type including an air directing portion having an air flow-way therethrough, means supplying said air flow-way with compressed air, and a particulate directing portion having a particulate flow-way therethrough communicating with said air flow-way to deposit said particulate material in said air flow-way, said control means comprisIng: air flow-way closure means operative to open and close said air flow-way; particulate flow-way closure means operative to open and close said particulate flow-way; and a sequencing mechanism operatively connected to said air flowway closure means and to said particulate flow-way closure means and having control fluid passageways and including means responsive to a first flow pattern of said control fluid in said control fluid passageways, when said air flow-way closure means and said particulate flow-way closure means are both open, to cause closing of said particulate flow-way by said particulate flow-way closure means first, followed by closing of said air flow-way by said air flow-way closure means; and means for selectively causing said control fluid to flow in said first pattern.

4. Control means according to claim 1 wherein said air flow-way closure means includes an air flow-way closure operator having first and second sides and movable in response to pressure on said first side thereof greater than pressure on the second side thereof to cause closing of said air flow-way; wherein said particulate flow-way closure means includes a particulate flow-way closure operator having first and second sides and movable in response to pressure on said first side thereof greater than pressure on said second side thereof to cause closing of said particulate; and wherein said sequencing mechanism has therein: a main control fluid passageway, an inlet for delivering said control fluid to said main control fluid passageway, an air closure passageway connecting said main control fluid passageway with a first area on said first side of said air flow-way closure operator, a one-way valve in said air closure passageway operative by pressure in said main control fluid passageway greater than the pressure in said first area to close said air closure passageway, a first bleed hole of smaller diameter than said main control fluid passageway connecting said main control fluid passageway to said first area, and a particulate closure passageway of greater diameter than said bleed hole connecting said main control fluid passageway with a second area on said one side of said particulate passageway closure operator.

5. Control means according to claim 4 wherein said sequencing mechanism further includes a one-way valve in said particulate closure passageway operative by pressure in said second area greater than the pressure in said main control fluid passageway to close said particulate closure passageway, and has therein a second bleed hole of smaller diameter than said main control fluid passageway connecting said particulate closure passageway to said main control fluid passageway.