US2306200A - Pneumatic bell hoist - Google Patents

Description

Dec. 22, 1942. A. J. WHITCOMB 2,305,200

PNEUMATIC BELL HOIST Filed June 15, 1940 mvENroR.

Ar 'ilzur J. Whifcomb Patented Dec. 22, 1942 PNEUMATIC BELL HOIST Arthur J. Whitcomb, Chicago, 111., assignor to Freyn Engineering Company, Chicago, 111., a

corporation of Maine Application June 15, 1940, Serial No. 340,857

Claims.

The present invention relates to improvements in pneumatic bell hoists.

A blast furnace of usual construction is provided at its top with a large bell and a small bell arranged in series with operating means for hold- 7 ing each of said bells in closed position and for permitting the opening of each bell. Operating means are known involving pneumatic cylinders connected to the large and small bells of a blast furnace, together with control means for admitting air under pressure to said cylinders and for discharging air from said cylinders.

It has been customary to operate the bell cylinders by air taken from the blast furnace cold blast main. This air may be at a pressure on the order of 10 to pounds per square inch, depending upon the size of furnace, character of burden, condition of burden, and other considerations.

In view of the rather moderate air pressure thus available it has been necessary and customary to provide air cylinders of rather large dimensions. The cylinder operating the large bell has been particularly large because of the higher cable pull necessary for closing the large bell and holding it closed. The pull upon the cable connected with the large bell must be sufficient at its maximum to hold the large bell closed when said bell is carrying a maximum load of materials. Not only must the bell be held closed, but there must be a marginal sealing pressure to insure that the bell holds tightly against its seat.

It has been common to supply sufiicient counterweight in connection with the bell operating cylinders so that the large bell will close due only to this counterweight provided there is no burden on the large bell. In any event, only a relatively light air pressure would be required to close the empty large bell and to hold it closed. However, as material is dumped onto the large bell, a greater cable pull is necessary in order to hold the bell closed.

It has not been considered generally desirable to use high pressure air such as air at 100 pounds per square inch for the general operation of the large bell, for three reaons: (a) A substantial amount of air would be required, necessitating a substantial supply source, and/or an air receiver of substantial dimensions. (b) It is more difficult to prevent leakage of air past the pistons and glands when such high pressure is used- This condition does not apply, however, if a pressure such as to pounds per square inch is not exceeded. (0) Air supply from the blast furnace plant system tends to accumulate water due to condensation.

An object of the present invention is to provide a pneumatic bell hoist adapted to utilize air at somewhat increased pressure over that available from the cold blast main without incurring the disadvantages of high pressure air, as mentioned above.

A further object is to provide a pneumatic bell hoist system adapted to use air such as may be had from the cold blast main for conditions where such relatively low pressure air is suitable and for supplementing said relatively low pressure air by means of air under higher pressure.

A further object is to provide a pneumatic bell hoist system which may embody instrumentaliv ties commonly provided in blast furnace plants.

A further object is to provide a pneumatic bellhoist system well adapted to meet the needs of 4, respectively, to the large bell and small bell arranged in series at the top of a blast furnace (not shown).

The numeral 5 indicates a conduit connecting with the cold blast, whereby air from the cold blast may be directed to the large and small bell operating cylinders I and 2. provided with a pressure gauge 6, the shut-off valve I, the check valve 8, and the pressure regulating valve 9. The numeral I0 indicates a safety valve, and the numeral I l indicates a pressure gauge. The conduit 5 is connected to a T I2, from which lead, a pipe I3 for supplying air to the large bell cylinder I and the pipe It for conducting air to the small bell cylinder 2.

Th pipe I3 is provided with the check valve I3a and the shut-off valve I5. Beyond the shutoff valve I5 the pipe I3 connects with the two three-way cocks, one of which is indicated by the numeral I6 and the other of which is indicated by the numeral H. The three-way cock I6 is connected through the pipe I8 to the large bell operating cylinder I, whereby when air under pressure is admitted through the pipe I8 the cylinder three-way cock I6 is also connected to the ex- Said conduit 5 is I will be forced downwardly. Said' haust pipe 26 provided with the speed regulating valve 2|.

The three-way cock I1 is connected to the pipe 22, which is connected with the large bell operating cylinder I in such a way that when air under pressure is admitted through the pipe 22 the large bell operating cylinder I will be raised. Said three-way cock I7 is connected by way of the speed regulating valve 23 and the pipe 26 to exhaust.

The two three-way cocks I6 and I! are connected to be operated in unison by means of the operator 24, which may be an electric motor controlled by any desired mechanism. S-aid operator 24 is adapted to control the vertical position of the rod 25, which is connected through cranks or other mechanism to the two three-way cocks I6 and I1. When said operator is in one position the pipe I3 will be connected throughthe three-way cock I 6 to direct air from said pipe l3 to the large bell cylinder I to force said cylinder downwardly. Under these conditions the three-way cock I! will be in position to discharge air from the large bell cylinder I through the speed regulating valve to exhaust. When the operator 24 is in its alternative position, the pipe I3 will be connected through the three-way cock I! to deliver air under pressure to the cylinder I to raise said cylinder. At this time the threeway cock I6 will be in position to discharge air from the cylinder through the speed regulating valve 2| to exhaust.

The pipe I4 is connected to the small bell cylinder 2 through the shut-off valve 26 and the two three- way cocks 21 and 28. Said three- way cocks 21 and 28 are connected to exhaust through the speed regulating valves 29 and 3E, respectively. Said three- way cocks 21 and 28 are connected to operate in unison in response to the operator 3|, which controls the positions of said three- way cocks 21 and 28 by means of the vertically reciprocable rod 32. The functions of the three- way cocks 21 and 28 are analogous to the functions of the three-way cocks I6 and I7, and no detailed description of these functions is necessary. In other words, each of the cylinders I and 2 has air under pressure applied alternatively to the two sides of its corresponding piston to positively move each of said cylinders reciprocally relative to its corresponding piston. In other words, each of the cylinders I and 2 is double-acting.

As indicated above, a feature of the present invention is the provision of means for supplying air when necessary to supplement the air delivered through the conduit from the relatively low pressure air supply. For providing this air at higher pressure the air receiver 32 is provided, having the air inlet 33 for supplying air under relatively high pressure, which may be on the order of 90 pounds per square inch. The outlet from said air receiver 32 is provided with the pressure gauge 33a and the safety valve 34. A pipe 35 is adapted to conduct air from the air receiver 32 -to the conduit 5, being connected to the conduit 5 in the illustrated embodiment of the invention betwen the check valve 8 and the pressure regulating valve 9. Said pipe 35 is provided with the shut-off valve 36, the check valve 31, the pressure regulating valve 38, the pressure gauge 39 and the safety valve 49. By reason of the pressure regulating valve 38, the pipe 35 maintains a constant low pressure for the conduit 5.

The air receiver 32 is also connected to the pipe I 3 through the pipe 4I. Said pipe M is provided with the shut-01f valve 42, the solenoid valve 43, the pressure regulating valve 44, the check valve 45 and the two-way cook 46. Said two-way cock 46 is connected by means of a crank, or other mechanism, to the reciprocable rod 25, which controls the three-way cocks I6 and It. Said two-way cock 46 will be open when the threeway cock I6 is in position to admit air from the pipe I3 to exert a downward pressure upon the large bell operating cylinder I, at which time the three-way cock I'I will be in position to exhaust air from said cylinder I. The two-way cock 46 will be closed when the three-way plug I! is in position to deliver air from the pipe i3 to exert a lifting efiect upon said cylinder I, at which time the three-way cock I6 will be in position to exhaust air from said cylinder. The solenoid valve d3 is connected electrically to the limit switch 41, which is closed when the large bell cylinder I is in its lowermost position and open when the cylinder I is lifted above its lowermost position. The solenoid valve 43 and the two-way cock 46 will both be open when the large bell operating cylinder is in its lowermost position to direct air under relatively high pressure from the air receiver 32 to the large bell cylinder I to provide a sealing pressure to hold said large bell cylinder I in its lowermost position to hold the large bell (not shown) in tightly closed position.

The pressure regulating valve 44 may function to cut down the -pound pressure of the air receiver 32 to about 40 pounds. The pressure regulating valve 38 may function to cut down the pressure from the air receiver 32 to approximately 15 pounds. The pressure regulating valve 9 may function to insure that the pressure from the cold blast main delivered through the conduit 5 does not exceed approximately 15 pounds. The check valves illustrated in the drawing and referred to hereinabove will, of course, function to prevent the backflow of high pressure air to regions of lower pressure.

The mode of operation of the above described embodiment of the present invention is substantially as follows:

The description may be started with reference to the parts in the positions shown in the drawing. Under these conditions air from the conduit 5, which may have a pressure on the order of 15 pounds per square inch, is delivered to the pipe I4, this relatively low pressure being maintained by the pressure regulating valves 38 and 9. Under these conditions air is admitted from the pipe I4 through the three-way cock 2'! to the cylinder 2 to hold said cylinder in its lowermost position to hold the small bell (not shown) in closed position.

Air from the conduit 5 at the relatively low pressure is also communicated to the pipe I3 and. through the three-Way cock I6 serves to hold the large bell cylinder I in its lowermost position, in which the large bell (not shown) is held in its closed position. The pressure of the air from the conduit 5 is supplemented by the air delivered through the pipe M from the air receiver 32. Though the air in the air receiver 32 may be under relatively high pressure, as'for example about 90 pounds pressure, this pressure will preferably be reduced to approximately 40 pounds by the pressure regulator 44. Therefore the relatively low pressure of, for example, about 15 pounds per square inch communicated to the pipe I3 by the conduit 5 will be supplemented by the relatively high pressure of for example, about 40 pounds per'square inch from the pipe 4|. Inasmuch as the large bell cylinder l is in its lowermost position, the limit switch 41 is closed and the solenoid valve 43 is open. The two-way cook 43 is also open at this time, whereby air under pressure of approximately 40 pounds per square inch is applied to the large bell cylinder I to hold the large bell tightly closed even when said large bell is being loaded with material.

When it is desired to lift the small bell cylinder 2 to dump the small bell, the operator 3! will be moved to swing the reciprocable rod 32 downwardly, whereby air from the pipe i l will be communicated to the small bell cylinder 2 to raise said cylinder, air being discharged from said cylinder through the three-way cock 2'! to exhaust.

When it is desired to open the large bell, the operator 24 will be operated to move the vertically reciprocable rod 25 to its lowermost position, shutting ofi the two-way cook 46 and moving the three-way cock I"! into position to admit air from the pipe I3 through the pipe 22 to cause the large bell cylinder I to lift. Lifting of the large bell cylinder I will open the limit switch 41, resulting in the closure of the solenoid valve 43.

When it is desired to move either of the bell cylinders l and 2 from its top position, the corresponding operator Zd or Si is operated to move its corresponding reoiprocable rod 25 or 32 to its uppermost position, connecting said cylinders to the pipes l3 and M, respectively, to cause the corresponding cylinder to move to its lowermost position. When the large bell cylinder reaches its lowermost position, the limit switch 41 will be closed, opening the solenoid valve 43. Inasmuch as movement of the reciprocable rod 25 to its uppermost position has opened the two-way cook 46, air at the relatively high pressure of approximately 40 pounds is communicated through the three-way cook it to hold the large bell cylinder l firmly in its lowermost position, whereby the large bell is tightly sealed.

The present invention has the advantage that a relatively small amount of high pressure air is required because of the fact that the large bell cylinder I has already been moved to its lowermost position and has already been filled with air at approximately pounds pressure. Only enough high pressure air is required to compress the air already in the large bell cylinder l and occupy the space made available as a result of such compression.

Though a preferred embodiment of the present invention has been described in detail, many modifications will occur to those skilled in the art. It is intended to cover all such modifications that fall within the scope of the appended claims.

What is claimed is:

1. In a pneumatic bell hoist system, in combination, a double-acting bell operating cylinder, a source of compressed air of relatively low pres sure, means for selectively admitting air from said source of relatively low pressure to said cylinder selectively to move said cylinder reciprocally, a source of compressed air at relatively high pressure, and means responsive to the position of said bell operating cylinder for providing connection of said source of high pressure air to said bell operating cylinder only when said cylinder is at the end of its bell-closing stroke.

2. In a pneumatic bell hoist system, in combination, a double-acting bell operating cylinder, a source of relatively low pressure air, valve means associated with said cylinder for con-. necting saidlow pressure source to said cylinder for selectively moving said cylinder reciprocally, a source of high pressure air, a valve for conmeeting said source of high pressure air to said bell operating cylinder through said valve means, and means for operating in combination said valve and said valve means to deliver air from said high pressure source to said cylinder through said valve and said valve means when said cylinder has reached the end of its bellclosing stroke.

3. In a pneumatic bell hoist system, in combination, a bell operating cylinder, a source of relatively low pressure air, valve means associated with said cylinder for connecting said low pressure source to said cylinder for selectively moving said cylinder reciprocally, a source of high pressure air, a valve for connecting said source of high pressure air to said bell operating cylinder through said valve means, means for operating in combination said valve and said valve means, and means responsive to the position of said bell operating cylinder for connecting said source of relatively high pressure air to said bell operating cylinder through said valve and said valve means at the end of the bellclosing stroke of said cylinder.

4. In a pneumatic bell hoist system, in combination, a bell operating cylinder, said cylinder being double-acting, a source of relatively low pressure air, valve means for connecting said cylinder to said source of low pressure air, said valve means having alternative positions for selectively moving said cylinder reciprocally, a source of high pressure air, a valve controlling connection between said source of high pressure air and said valve means, means for operating said valve means and said valve in combination, and means cooperating with said valve and valve means for connecting said source of high ressure air to said cylinder only when said cylinder is in bell-closing position.

5. In a pneumatic bell hoist system, in combination, a double-acting bell operating cylinder,

a source of relatively low pressure air, valve means adapted to be alternatively positioned to cause air from said source of low pressure air to move said cylinder selectively in opposite directions, a source of high pressure air, and means operative only when said cylinder is in hell closing position to supply air from said source of high pressure air to said cylinder.

6. In a pneumatic bell hoist system, in combination, a bell operating cylinder, a source of relatively low pressure air, valve means adapted to be alternatively positioned to connect said source to said cylinder to selectively move said cylinder in opposite directions, a limit switch cooperatively associated with said cylinder, a source of high pressure air, and a pair of valves for connecting said source of high pressure air to said cylinder, one of said valves being operable in combination with said valve means, the other of said valves being responsive to said limit switch.

'7. In a pneumatic bell hoist system, in combination, a bell operating cylinder, a source of relatively low pressure air, valve means adapted to be alternatively positioned to cause air from said source of low pressure air to move said cylinder selectively in opposite directions, a source of high pressure air, 'and'a pair of valves for connecting said source of high pressure air to said cylinder through said valve means, one of said valves being operable in combination with said valve means, the other of said valves being responsive to the position of said cylinder.

8. In a pneumatic bell hoist system, in combination, a bell operating cylinder, a source of relatively low'pressu-re air, valve means adapted to be alternatively positioned to connect said source to said cylinder to selectively move said cylinder in opposite directions, a source of high pressure air, and means for connecting said source of high pressure air to said cylinder only when said cylinder is in bell-closing position.

9. Operating means for a bell of a blast furnace comprising, in combination, a cylinder having a piston therein, means for supplying air under relatively low pressure alternatively to said cylinder at the two sides of said piston to communicate reciprocatory motion to said cylinder, and means for supplying air at relatively high pressure to said cylinder for holding said cylinder tightly in bell-closing position after said cylinder has reached bell-closing position.

10. Operating means for a bell of a blast furnace comprising, in combination, a cylinder having a piston therein, means for supplying relatively low pressure air to one side of said piston for raising said cylinder and for exhausting air from said cylinder at said one side of said piston, and means for supplying air at a relatively high pressure to said cylinder for holding said cylindertightly in bell-closing position after said cylinder has reached bell-closing position.

ARTHUR J. WHITCOMB.

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