US2831554A - Control device for hoists - Google Patents

Description

April 1958 H. c. REYNOLDS I 2,831,554

CONTROL DEVICE FOR norsrrs Filed July so, 1951 2 Sheets-Sheet 1 1 'I IIIIIF INVENTOR HAROLD C. REYNOLDS HIS ATTORNEY H. c. REYNOLDS 2,831,554

A ril 22, 1958 CONTROL DEVICE FOR HOISTS Filed July 30, 1951 2 Sheets-Sheet 2 as as L as 3 9o 86 86 8B 90 87 HAROLD 0. REYNOLDS HIS ATTORNEY United States CGNTRUL DEVICE FUR HOISTS Application July 30, 1951, Serial No. 239,263

3 Claims. (Cl. 192-3) This invention relates to pneumatic hoists and more particularly to control devices for pneumatic hoists.

In the operation of overhead pneumatic hoists it is highly desirable to have a simple, sensitive controlling means easily accessible to the operator. A common type of controlling means having these features is the pendent throttle type of control wherein the supply air for the hoist passes through a manually operated throttle valve and thence directly to the driving motor of the hoist. However, this type of control is not applicable to the hoists of large capacity because the volume of air passing through the pendent throttle is so large that a sensitive control is not possible and the throttling valve of necessity must be large and bulky. For this reason it has, heretofore, been the practice to equip large capacity hoists with the less-desirable pull chain type of control.

It is an object of this invention to provide a control device for pneumatic hoists of largecapacity utilizing a manually operated control valve of the pendent throttle type.

Another object of the invention is to construct a control device for pneumatic hoists having automatic means for limiting the upward and downward travel of the hoist cable.

A further object of the invention is to construct a control device which will prevent the hoist from picking upthe load before the brake is released.

Other objects of the invention will be in part obvious and in part pointed out hereinafter.

in the drawings in which similar reference numerals refer to similar parts,

Figure 1 is a side elevation of a hoist equipped with applicants control device;

Figure 2 is a sectional view of the valve casing taken along the line 2-2 in Figure 3 looking in the direction of the arrows,

Figure 3 is a vertical section of the valve casing taken along the line 33 in Figure looking in the direction of theyarrows,

Figure 4- is a sectional View of the brake for the hoist taken along the line 4-4 in Figure 1 looking in the direction of the arrows,

Figure 5 is a transverse-vertical section of the valve casing taken along the line 55 in Figure 3 looking in the direction of the arrows and Figure 6 is a sectional view of the manual control valve for the hoist taken along the line 66 in Figure 1 looking inthe direction of thearrows.

A fluid-actuated hoist, constructed in accordance with the teachings of the applicants invention, is shown in Figure l and is designated generally by the numeral 16. The hoist it) comprises a pressure-fluid driven motor 11, preferably of the reciprocating piston type, a cable drum 12 upon which the hoist cable 13 is Wound and a gear casing 14 housing the gears (not shown) that transmit the power of the motor to the cable drum. At one end of the hoist casing there is a valve casing 29 containing control mechanisms which, in conjunction with the manatent by spool valves 34-.

ually operated throttle valve 16 depending from the hoist, control the operation of the hoist. A braking mechanism 15 of the pressure fluid-actuated type is also provided to effect locking and unlocking of the cable drum 12.

The valve casing Ell is shown (Fig. 3 and Fig. 5) appended the motor casing ll and at its uppermost portion is provided with a cylindrical opening 21. Seated within this opening 21 is a bearing 22 having a rotary valve 23 for distributing pressure fluid to the cylinders of the motor ill. The lower portion of the valve casing 2 is provided with a receiver chamber 2 5 having a pair of openings 25 i a pair of valve chambers 26. Seated within each opening 25 is a bushing 27 having an opening 28 therein and a cylindrical extension 29 which projects into a valve chamber 26. The extensions on the bushings have apertures iii) in the walls thereof to communicate the interiors Fall of the extensions 29 with the valve chambers 26. The valve chambers 26 communicate with the distributing valve 23 through passageways 32. and with the atmosphere through the passageways 33.

Referring now to Figure 5 communication between the chamber 24 and the valve chamber as is controlled Each spool has a pair of rings 35 attached thereto and so arranged that one: ring abuts the inner surfaces of the bushings 27 adjacent the openings 28. A spring 37 constantly urges the valves 34 toward their closed positions. For the purpose of controlling the action. of the valves diaphragms 38 and 3% are secured to valve lifters 4b. The diaphragms 38, 39 divide the valve chambers 26 into three compartments; an outermost or end compartment ll for control fluid; an intermediate compartment 42 in communication with the atmosphere through the passageway 33%; and an innermost compartment 43 for the supply fluid for the hoist. The intermediate compartment 4%.; is communicated with the innermost compartment 43 whenever the valve 34 is open through the internal bore 44 and access holes 4-5 in the valve lifters ib. When the valve 34 is closed the inner surfaces as of the valve lifters ltl abut the extensions 29 on the bushings 27 and the ring 35 of the spool and block ofl comunication between the compartments 4-2 and t3.

Whenever the diaphragms .33, 39 and the valve lifters as are in their outermost positions, the valves 34, urged by the spring 37, will abut the openings 9.3 and prevent flow of pressure fluid from the receiver chamber 25 to the compartments i3. Whenever the diaphragms are in their innermost positions, the inner surfaces 46 of the valve lifters ill will abut the rings 35 of the valves 34 and move the valves into their open position, thereby communicating the compartments 4,3 with the receiver chamber 24. The movement of the valves is effected by admitting fluid under pressure to the end compartments 41 of the valve chambers where the pressure of the fluid acts against the diaphragms 39 and exerts its force in opposition to the springs 47 tending to move the valve lifters and the diaphragms to their outermost position. The admission of the control air to the end compartments 41 of the valve chambers is controlled by a manually operated valve 16, depending from the hoist so as to be within the hoist operators reach and having a hand gripping portion 4b and a pair of levers 49 which may be conveniently actuated by the operator with his thumb or finger.

The control fluid is obtained by bleeding-oh to the valve 16 a portion of the supply fluid brought to the receiver chamber 24 by the conduit 54). This is accornplished by means of passageway 51 (Figure 3) in the valve casing 20 communicating with the receiver chamber 24. The pressure fluid passes through the passageway to communicate the chamber with 51, through a ceramic filter 52 secured within a housing 53, into the compartment 54 shown in the Figure 2, and thence through the passageway 55 and the conduit 56 to the manually operated valve 16.

The pressure fluid is delivered to a chamber 57 in the valve 16 having a pair of openings 58, each communicating with a conduit 59 leading to the end compartments 41 of the valve chambers. The passage of fluid from the chamber 57 to the conduits 59 is controlled by a pair of valves 60 constantly urged towards their seats by springs 61. At their opposite ends the valves- 66 are provided with pistons 62, residing in bores 63 and abutting the thumb levers 49 so that movement of either thumb lever moves the corresponding piston inwardly causing the valve to move ofr its seat and to communicate. the

chamber 57 with the desired conduit 59. Each of the bores 6.3 is communicated with a passageway 65 leading to the atmosphere whenever the valves 60 are in their closed position so that pressure fluid in the conduits may escape through the passageways 65 to the atmosphere. The passageways are so positioned that when the valves 60 are opened, the pistons 62 block off the passageways 65 and prevent the escape of fluid to the atmosphere.

The conduits 59 communicate with a cylindrical chamber 66 in the valve casing 26 at the opposite ends thereof and the outermost compartments 41 through passageways 67. Pressure fluid is thus permitted to flow through the conduits 59 to the end compartments 41, of the valve chamber where the fluid acts upon the diaphragms 39. The cylindrical chamber 66 has a shuttle valve 68 located therein which is freely slidable within the chamber 66 and at each limiting position of its travel closes ofl one of the conduits 59. Whenever there is a flow of fluid through either conduit 59 a portion of the fluid flowing therethrough will be communicated with the shuttle valve 68 thereby causing the shuttle valve 68 to slidably move to its opposite limiting position where the valve closes ofl the other conduit 59. In moving to the opposite extreme position of its travel, the shuttle valve 68 uncovers a conduit 69 which leads to the pressure fluid-actuated brake of the hoist.

The brake 15 (Figure 4) comprises a casing 70 housing a large internal gear 71 which engages a smaller gear 72 connected to the rotating mechanism of the hoist drum 12. In order to lock the hoist drum against rotation a brake band 73 is provided around the periphery of the internal gear 71. As is customary, one end 74 of the brake band 73 is securely fixed while the other end 75 of the brake band is movable so that movement of the end of the brake band either tightens or loosens the brake band on the surface of the internal gear 71. To effect such movement of the brake band, a cylinder 76 is provided having a piston 77 residing therein and connected to the free end 75 of the brake band 73 by means of a piston rod 79 so that movement of the piston 77 results in move ment of the end of the brake band. 'The piston 77 is constantly urged in a direction for tightening the brake band by a spring 80 and movement in the opposite direction for releasing the brake band is effected by admitting pressure fluid into the cylinder 76 through the passageway 69. Whenever the shuttle valve 68 uncovers the passageway 69, pressure fluid flows through the conduit into the cylinder 76 and acts against the piston to force the piston to move against the tension of the spring 80 to loosen the brake band 73 from the internal gear 71, thereby allowing rotation of the hoist.

In Figure 5 the control device is shown in a position for raising the load on the hoist. Pressure fluid from an external source (not shown) passes through the conduit 5!) into the receiver chamber 24. A portion of this supply fluid flows through the passageway 51, through the filter 52., the passageway 55 and the conduit 56 to the manually operated control valve 16. As it is desired to raise the load on the hoist, the operator presses the righttit) 4 hand thumb lever 49 which lifts the valve 60 011 its seat thereby communicating the chamber 57 with the righthand conduit 59. Fluid then flows through the conduit 59 and passageway 67 into the end compartment 41 of the valve chamber 26. g

A portion of this control air is directed against the shuttle valve 68 and causes it to move to its extreme leftwardly position as shown in the figure, thereby uncovering the passageway 69 and allowing the fluid to flow through the conduit 69 to the cylinder 76. The pressure fluid continues to he admitted to the cylinder 76 until there is sutficient pressure in the cylinder acting on the piston 77 to overcome the force of the spring and to release the brake 15.

Because the tension of the spring 47 is selected to prevent the opening of the valve 34 until after the brake has been released there is a delay before the actuation of the valve 34 by the diaphragm 39 while the pressure in the chamber 41 increases to a value suflicient to overcome the force of the spring. Once suflicient pressure has been admitted to the chamber 41 it acts on the diaphragm 39 to move the valve 34 ofl its seat. Supply fluid then flows from the receiver chamber 24 through the opening 28 into the valve chamber 26 from which it passes through the passageway 32 to the distributing valve 23 for distribution to the motor. The air exhausted from the motor passes through the left-hand passageway 23 into the valve chamber 26, then through the internal bore 44 to the lefthand intermediate compartment 42 of the valve chamber 26 and out through the passageway 33 to the atmosphere.

The area of the diaphragm 39 is greater than that of the diaphragm 38 by an amount which, when acted upon by a maximum control fluid pressure, will compensate for the force exerted in an opposite direction by the spring 47. Inasmuch as the pressure of the control fluid at the time of unseating the valve 34 is not at a maximum, the pressure in the chamber 41 is somewhat higher than the pressure of the supply fluid entering through the valve 34, however, subsequent increments in control fluid pressure will result in substantially the same pressure increments in the supply fluid because the diflerential between the pressure of the control fluid and that of the supply fluid decreases as more fluid is admitted to the chamber 41 until at full throttle the supply pressure is equal to the pressure of the control fluid. Thus a sensitive control of the hoist is obtained since for any given change in the pressure of the control fluid, a corresponding and substantially equal change occurs in the pressure of the fluid being supplied to the motor of the hoist.

The diaphragms 38, 39 in the left-hand valve chamber 26 are in their extreme leftwardly positions because the tension on the spring 47 has so moved them and that the end compartment 41 is devoid of controlling fluid since the compartment is in communication with the atmosphere through the conduit 59 and the passageway 65 in the manually operated valve 16.

Whenever it is deisred to lower the load on the hoist, the left-hand thumb lever 49 is pressed by the operator whereupon the same sequence of operation takes place to open the left-hand valve 34 and to admit pressure fluid to the motor to cause it to rotate in the opposite direction. The control fluid in the end compartment 41 is exhausted to the atmosphere through the passageway 65 m the manually operated valve 16.

The hoist is provided with means for limiting the upward and downward travel of the hoist cable on the cable drum and this means comprises a pair of automatic cable control devices 81 communicating the end compartments 41, with the atmosphere. Whenever the cable is excessively wound or unwound the control devices 81 exhaust the pressure fluid in the end compartments 41, thus permitting the spring 37, to close the valves 34 and stop the flow of motive fluid to the motor. To this end a lever 82, pivoted on a pin 83, is provided on the hoist casing. lever is so located that upon an excessive unwinding of the cable from the hoist drum a stop 84, fastened to the cable adjacent one end, comes into contact with the lever and causes it to pivot about the pin 83. Such pivotal movement of the lever causes the opposite end thereof to contact a valve plunger 85 in the valve casing 86 thereby lifting a valve 87 off its seat 88 and communicating the left-hand end compartment 41 with the atmosphere through the conduit 89 and ports 90 in the valve casing 86. A similar controlling device is provided so that when the lever 82 is enegaged by the hook 91 and pivoted thereby the control fluid in the right-hand end compartment 41 will be exhausted to the atmosphere in a similar manner. In this way the upward and downward travel of the hoist cable is limited.

I claim:

1. A speed control device for hoists comprising in combination a pressure fluid actuated motor for the hoist, a conduit for conveying pressure fluid to the motor, a pressure control valve acting proportionately to control fluid pressure for controlling the flow and pressure of the fluid passing through the conduit to the motor, a pressure fluid actuated braking mechanism for the hoist, a conduit for conveying control pressure fluid to the pressure control valve and to the fluid actuated braking mechanism, a manually operated control valve in the lastmentioned conduit to regulate the flow and pressure of the fluid passing to the pressure control valve and to the pressure fluid braking mechanism, and means for delaying the operation of the pressure control valve until after the actuation of the braking mechanism.

2. A speed control device for hoists comprising in combination a pressure fluid actuated motor for the hoist, a conduit for conveying pressure fluid to the motor, a pressure control valve acting proportionately to control fluid pressure for controlling the flow and pressure of the fluid passing through the conduit to the motor, a conduit for conveying control pressure fluid to the pressure control valve, a manually operated control valve in the last-mentioned conduit to regulate the flow and pressure of the fluid passing to the pressure control valve, and means for automatically exhausting the control fluid from the pressure control valve to close the valve and thereby prevent excessive winding and unwinding of the hoist cable.

3. A speed control device for hoists comprising in combination a pressure fluid actuated motor for the hoist, a conduit for conveying pressure fluid to the motor, a pressure control valve acting proportionately to control fluid pressure for controlling the flow and pressure of the fluid passing through the conduit to the motor, a pressure fluid actuating braking mechanism for the hoist, a conduit for conveying control pressure fluid to the pressure control valve and to the fluid actuated braking mechanism, a manually operated control valve in the lastmentioned conduit to regulate the flow and pressure of the fluid passing through the last-mentioned conduit, means for delaying the operation of the pressure control valve until after the actuation of the braking mechanism, and automatic means for exhausting the control fluid from the pressure control valve to close the valve and thereby prevent excessive winding and unwinding of the hoist cable.

References Cited in the file of this patent UNITED STATES PATENTS 991,059 Hammond et al. May 2, 1911 1,553,614 Hukill Sept. 15, 1925 1,596,269 Jimerson et a1. Aug. 17, 1926 2,171,204 Vickers Aug. 29, 1939 2,246,923 Meunier June 24, 1941 2,328,684 Schnell Sept. 7, 1943 2,376,918 Hughes May 18, 1945 2,477,836 Stevens Aug. 2, 1949 2,566,708 Trevaskis Sept. 4, 1951 FOREIGN PATENTS 560,201 Great Britain Mar. 24, 1944

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