US3348378A - High pressure fail-safe gate-operating apparatus - Google Patents

Description

Oct. 24, 1967 K. F. LEMLEY 3,348,378

HIGH PRESSURE FAIL-SAFE GATE-OPERATING APPARATUS Filed April 25, 1966 INVENTOR. AfW/VfT/v F. LE'MLEV ATTORNEKfi United States Patent 3,348,378 HIGH PRESSURE FAIL-SAFE GATE-OPERATING APPARATUS Kenneth F. Lemley, 144 Woodhaven Lane, Pittsburgh, Pa. 15237 Filed Apr. 25, 1966, Ser. No. 544,987 9 Claims. (Cl. 60-57) a reservoir immediately will be connected with the cylinder to close the gate. That system has proved to be very satisfactory, but when the gate-operating cylinder is quite large the compressed air tank or reservoir has to be made much larger than desired and occupies too much space. This is because the air in the reservoir is at the same relatively low pressure as that delivered by the compressor which normally operates the gate, and therefore there has to be a large volume of this compressed air stored in the reservoir to ensure closing of the gate. 7 It is among the objects 'of this invention to provide apparatus similar to that shown in my Patent 3,225,544, which can utilize a small compressed air reservoir for operating a large gate-operating cylinder, which requires no additional power except an insignificant amount of electricity for closing a valve, and which is entirely automatic.

In accordance with this invention, a-reservoir contains compressed air that is used only for closing agate in emergencies. There is a source of compressed air for Keeping the reservoir charged. Likewise connected to the reservoir is a pressure intensifier that increases the air pressure in the reservoir above the pressure supplied by the source just mentioned. This intensifier includes a cylinder containing a piston for operating the intensifier. A pair of conduits are connected with the cylinder at 0pposite sides of the piston and with a reversing valve. The reversing valve is connected with the compressed air source for connecting it with the conduits alternately in order to reciprocate the piston. Means are provided for operating the reversing valve, preferably from the compressed air in the system.

The preferred embodiment of the invention is illustrated schematically in the single figure of the a'ccornpanying drawing.

Referring to the drawing, it includes a reproduction of all of FIG. 1 of the drawings in Patent 3,225,544. The reproduced parts also have been given the same numbers as in the patent, but some of them will be described more briefly herein. For a more detailed description, if desired, reference may be made to the patent. In the drawing of this aplication, the bottom outlet of a hopper or bin 1 is shown closed by a door or gate 2 that can slide in stationary tracks 3. For reciprocating the gate in order to open and close it, one end of it is pivotally connected by a link 4 to the upper end of a lever 5, the lower end of which is pivotally connected to the outer end of a piston rod 6 attached to a piston 7 in a fluid pressure cylinder 8. The lever is pivotally connected to a suitable support 9. It will be seen that when the piston is moved to the left-hand end of the cylinder the link and lever will pull the gate away from the bottom of the bin to open its outlet. When the piston is returned to the right-hand end of the cylinder, the gate will be closed.-

For accomplishing these movements of the piston in the cylinder, a pipe 11 is (onnected to the right-hand end or gate-closed end of the cylinder, while another pipe 12 is connected to the opposite or gate-open end of the'cylinder. These pipes may be flexible in Whole or in part if desired. Both pipes terminate at control means for selectively connecting a source of compressed air with either of them and for connecting the other pipe with the atmosphere. Such means may include a conventional fluid pressure operated valve 13 having a solenoid- .actuated pilot. As shown, the valve connects pipe 11 with the atmosphere and simultaneously connecting pipe 12 with a line 18 leading from a source of compressed air, such as a compressor 19. When the control valve is reversed, it connects the compressor with pipe 11 and connects pipe 12 with the atmosphere. Thus, by operating .this valve, air pressure can be delivered to either end of cylinder 8 in order to move the piston therein back and forth. The apparatus described thus far is satisfactory as long asthe necessary air pressure is maintained in'line 18.

However, if while the gate is open, the air pressure in the system should happen to drop below the amount necessary to close the gate, thirty pounds per square inch absolute for example, emergency apparatus will come into operation automatically to move piston 7 towards the gate-closed end of the cylinder. Accordingly, pipe 12 is provided with a first valve 23 that normally is closed by a closure member 25. However, the valve contains fluid pressure responsive means for opening it, which may be a plunger 26 slidably mounted in the bottom of the valve, which opens into the upper end of a tube 29 connected with compressed air line 18. As soon as pressure in the line is built up to a predetermined point, it will force the plunger upward and thereby open the valve as shown so that compressed air can flow through pipe 12 to cylinder 8 when control valve 13 .is in the position shown. When the control valve is reversed, air from the cylinder will escape through valve 23 and the control valve to the atmosphere. As long as the gate-operating apparatus is in use, and functioning properly, valve '23 will remain open;

Also connected with the compressed air line -18 is a. reservoir 31, which is charged with compressed air from the compressor. This reservoir is connected by a conduit 32 with pipe 12 between valve 23 and cylinder 8. This conduit contains a second valve 33 that normally is held open by a coil spring 34 pressing the movable closure member 35 away from its seat. This valve likewise contains fluid pressure responsive means, which may be in the form of a plunger 37 in the bottom of the valve. The bottom of the valve is connected by a tube 40 to compressed air line 18, so that While the compressor is opertion of this apparatus, valve 23 is held open and valve 33 is held closed by the compressed air delivered by the compressor through line 18 and tubes 29 and 40. However, in case there is a failure of pressure while the gate is open so that it cannot be closed in the normal ,way by compressed air flowing through valve 23, the drop in pressure below a predetermined value will permit the valve 23 to close and valve 33 to open. The moment valve 23 is opened, compressed air in the reservoir is connected through conduit 32 and pipe 12 with the left-hand end of the operating cylinder to drive piston 7 toward the opposite end of the cylinder and close the gate. After the diffieulty that reduced the air pressure has been corrected so that the proper pressure can be built up in the system again, the air from the compressor Will reopen valve 23, close valve 33 and recharge the reservoir through check valve 41. The reservoir is then ready to operate the piston again if another emergency should ever arise.

Obviously, the capacity of the reservoir should be great enough to provide sufiicient air pressure to force the piston toward the gate-closed end of the cylinder and hold it there. To ensure having sufficient pressure for this purpose, and yet not provide a reservoir that is larger than it needs to be, the proper size for the reservoir can be determined in advance. It can be determined by multiplying the air pressure .per square inch absolute in the charged reservoir by the volume of the reservoir, and dividing the product by the combined volume of the reservoir and cylinder. The result will be the air pressure per square inch absolute available for shifting the piston in its cylinder. In this way a reservoir can be selected that will provide the desired air pressure for operating the piston.

The apparatus described thus far is perfectly satisfactory for its intended purpose, but in installations where cylinder 8 becomes quite large, reservoir 31 also would have to be made much larger, except for this invention. Accordingly, it is a feature of this invention that regardless of the size of cylinder 8, reservoir 31 can be maintained quite small. This is accomplished by providing the apparatus with means for greatly augmenting the air pressure in the reservoir, such as by an intensifier 50 which is formed from two aligned cylinders containing two pistons. The upper cylinder 51 is shown considerably larger than the lower one 52, and therefore the .upper piston 53 is much larger than the lower piston 54. The two pistons are rigidly connected together by a rod 55. The lower part of the small cylinder is supplied with compressed air through an extension 57 of compressed air line 18. This pipe is provided with a check valve 58 that opens toward the intensifier. The same part of the intensifier is connected by a discharge pipe 59, containing a check valve 60, with the reservoir 31.

To move the upper piston 53 up and down in its cylinder in order to reciprocate the lower piston and thereby force air under high pressure through pipe 59 into the reservoir, a conduit 62 is connected to the upper end of .uppr cylinder '51 and another conduit 63 is connected to the lower end of the cylinder. Both conduits lead to a reversing valve 64 of the bi-sta-ble type, in which a pair of valve members 65 and 66 are movable back and forth in chambers 67 and 68 by pistons 69 and 70 and coil springs 71 and 72. When the valve members are held in their left-hand positions by the springs, as shown, a passage 73 connects conduit 62 with the atmosphere by means of chamber 67 and a passage 74. At the same time, an inlet passage 75 from line 18, containing a normally open solenoid shutoff valve 76, is connected through chamber 68 and a passage 77 with the lower conduit 63.

With the valves in the positions shown, air under pressure from compressor 19 is entering the bottom of the large cylinder of the intensifier and thereby forcing the piston therein to rise. When the reversing valve 64 is reversed, the lower conduit 63 is connected with exhaust through chamber 68 and a passage 78, and upper conduit 62 is connected-with inlet passage 75 through chamber 67, so that air pressure from line 18 will be applied to the top of the upper piston 53 to force it down in its cylinder. It .will thus be seen thatit the reversing valve is reversed periodically, the pistons in the intensifier will be reciprocated by air from the compressor and some air from the compressor will be increased in pressure by the intensifier and delivered to the reservoir. Consequently, the air in the reservoir can be maintained at a much higher pressure than the compressor can supply, so that in an emergency there will be a sufiicient volume of compressed air to operate gate cylinder 8 even though the reservoir is relatively small as compared with the gate cylinder.

Another feature of this invention is that air from the compressor is used as the motive power for reversing the reversing valve 64. For this purpose, the conduit 63 is connected by a branch pipe 80 to a pneumatic timer 81 that is connected to the left-hand end of the reversing valve. This timer permits air from the compressor to periodically move pistons 69 and 70 and valve members 65 and 66 in the reversing valve to the right against the resistance of the coil springs pressing against them, whereupon the pistons in the intensifier 50 will be driven downward until the timer allows the coil springs to return the valve member to the left-hand position.

The timer may be formed from two timing valves 82 and 83 connected in .parallcLEach of these valves is provided with an orifice adjustable by a needle 84 to permit air to flow through the valve at a controlled slow rate. The two valves are connected at one end by a pipe 85 connected to branch pipe 80, while their opposite ends are connected by a pipe 86 that in turn is connected with a passage 87 in the reversing valve leading to the two pistons therein. Between passage 87 and timing valve 82 there is a check valve 88. Between the other timing valve and pipe 80 there is another check valve 89. One of these check valves opens toward the reversing valve and the other one opens away from it.

It will be seen that while compressed air is entering the bottom of the large cylinder 51 of the intensifier, it also is flowing slowly through pipes 80 and 85 and timing valve 82 and into the adjacent end of the reversing valve. At about the time the pistons in the intensifier reach the tops of their cylinders, the air pressure against the pistons in the reversing valve becomes great enough to unbalance the valve members therein and shift them to the right, thereby connecting the compressor with the top of the intensifier and connecting the bottom of the large piston 53 with exhaust. Of course, at the same time the timer is connected with exhaust through pipe 80, As the air pressure against the reversing valve pistons slowly discharges through timing valve 83 to exhaust, the intensifier pistons are being moved downward to increase the pressure of the air in reservoir 31. At about the time they reach the lower ends of their cylinders, the air pressure in the reversing valve has been reduced to such a point that springs 71 and 72 can expand and quickly push valve members 65 and 66 back to their original positions, wherein the compressor again will be connected with conduit 63 and the timer, while the upper conduit 62 will be connected with exhaust. This automatic periodic reversal of the reversing valve therefore causes the intensifier to operate like a pump and increase the air pressure in the reservoir.

When the pressure in the reservoir reaches the desired level, provision is made for shutting 01? the intensifier. This may be done by connecting the solenoid coil 90 of the shutolf valve 76 with a normally-open fluid pressure switch 91 responsive to the air pressure in the reservoir. When that pressure rises to the desired value, it will move the diaphragm 92 in the pressure switch to the left and thereby cause a bridging bar 93 to span the electric contacts 94 so that the circuit to the shutoff valve will be closed. This will cause the valve member 95 in that valve to be moved to the right in order to shut oif flow of compressed air to the upper cylinder 51 of the intensifier. Whenever the pressure in the reservoir drops, due to leakage or to use of the air therein, pressure switch 91 will open again and that will allow the shutoif valve to open so that the intensifier can start operating again to build the pressure in the reservoir back up to the desired level.

It will be observed that the intensifier is operated entirely automatically by the same compressor that charges the compressed air reservoir, and that the only additional power required is the electricity used for closing shutoif valve 76, when the pressure in the reservoir is at its maximum.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In fail-safe gate-operating apparatus having a reservoir containing compressed air that is used only for closing a gate in emergencies, and a source of compressed air for charging the reservoir, of a pressure intensifier connected with said reservoir for increasing the air pressure in the reservoir above the pressure supplied by said source, said intensifier including a cylinder containing a piston for operating the intensifier, a pair of conduits connected with the cylinder at opposite sides of the piston, a reversing valve connected with said source for connecting it with said conduits alternately to reciprocate the piston, and means for operating the valve.

2. In fail-safe gate-operating apparatus according to claim 1, said valve connecting one conduit with the atmosphere when it connects the other with said source, and said valve-operating means including a spring urging the valve in one direction and an air line permanently connected with one of said conduits to employ the pressure from said source for moving the valve in the opposite direction.

3. In fail-safe gate-operating apparatus according to claim 2, said fluid pressure line containing a timer comprising an air passage provided with a restricted orifice and a check valve opening toward the reversing valve, and a second air passage provided with a restricted orifice and a check valve opening away from the reversing valve.

4. In fail-safe gate-operating apparatus according to claim 1, said intensifier receiving compressed air from said source, increasing its pressure and delivering it to the reservoir.

5. In fail-safe gate-operating apparatus according to claim 1, a normally-open valve connecting said source with said reversing valve, and means controlled by the pressure in said reservoir for closing said normally-open valve when that pressure rises to a predetermined value.

6. In fail-safe gate-operating apparatus according to claim 5, said normally-open valve being electrically operable, and said pressure-controlled means being a normally-open pressure switch electrically connected with said normally-open valve and closable by a predetermined pressure in said reservoir.

7. In fail-safe gate-operating apparatus according to claim 1, a conduit connecting said source with the intensifier for delivering compressed air thereto to be increased in pressure thereby and delivered to the reservoir,

a normally-open electrically operated valve connecting said source with said reversing valve, said pressure-controlled means being a normally-open pressure switch electrically connected with said normally-open valve and closable by a predetermined pressure in said reservoir, said reversing valve connecting one of said pair of conduits with the atmosphere when it connects the other with said source, and said valve-operating means including a spring urging the reversing valve in one direction and an air line permanently connected with one of said pair of conduits to employ the pressure from said source for moving the reversing valve in the opposite direction and containing a pneumatic timer.

8. Fail-safe gate-operating apparatus comprising a fluid pressure cylinder, a piston therein, a piston rod attached to the piston and extending out of one end of the cylinder for opening and closing a gate, pipes connected to the opposite ends of the cylinder, a source of compressed air, control means for selectively connecting said source with either of said pipes and connecting the other pipe with the atmosphere to move the piston from one end of the cylinder to the other, a normally closed first valve in the pipe that delivers compressed air to the end of the cylinder from which the piston moves to close the gate, said valve containing fluid pressure responsive means for opening it, means for delivering compressed air from said source to said pressure responsive means to hold the valve open during normal operation of the apparatus, a reservoir, a conduit connecting the reservoir with said valved pipe between said valve and cylinder, a normally-open second valve in said conduit provided with fluid pressure responsive means for closing it, means for delivering compressed air from said source to the pressure responsive means of the second valve to hold that valve closed during normal operation of the apparatus, a conduit connecting said source of compressed air with the reservoir, a check valve in said last-mentioned conduit permitting flow of air therethrough only toward the reservoir to charge it with compressed air, a pressure intensifier connected with said reservoir for increasing the air pressure in the reservoir above the pressure supplied by said source, said intensifier including a cylinder containing a piston for operating the intensifier, a pair of conduits connected with the cylinder at opposite sides of the piston, a reversing valve connected with said source for connecting it with said pair of conduits alternately to reciprocate the piston, and means for operating the reversing valve.

9. Fail-safe gate-operating apparatus according to claim 8, including a shut oil valve normally connecting said source with said reversing valve, and means controlled by the pressure in said reservoir for closing said shut-01f valve when that pressure reaches a predetermined maximum.

No references cited.

EDGAR W. GEOGHEGAN, Primary Examiner.

Claims (1)

1. IN FAIL-SAFE GATE-OPERATING APPARATUS HAVING A RESERVOIR CONTAINING COMPRESSED AIR THAT IS USED ONLY FOR CLOSING A GATE IN EMERGENCIES, AND A SOURCE OF COMPRESSED AIR FOR CHARGING THE RESERVOIR, OF A PRESSURE INTENSIFIER CONNECTED WITH SAID RESERVOIR FOR INCREASING THE AIR PRESSURE IN THE RESERVOIR INCLUDING A CYLINDER CONBY SAID SOURCE, SAID INTENSIFIER INCLUDING A CYLINDER CONTAINING A PISTON FOR OPERATING THE INTENSIFIER, A PAIR OF CONDUITS CONNECTED WITH THE CYLINDER AT OPPOSITE SIDES OF THE PISTON, A REVERSING VALVE CONNECTED WITH SAID SOURCE FOR CONNECTING IT WITH SAID CONDUITS ALTERNATELY TO RECIPROCATE THE PISTON, AND MEANS FOR OPERATING THE VALVE.

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