US2823775A - Hoist motor and brake control - Google Patents

Description

Feb. 18, 1958 2 Sheets-Sheet. 1

Filed Feb. 28, 1955 8 m w 5 mm m 5 4 m w a 5 mm E R 4 I u U V 8 i m 2 a KZL 4m I ATTORNEYS United States Patent f HOIST MOTOR AND BRAKE CONTROL Robert E. Zwayer, Bryan, Ohio, assignor to ARO Equipment Corporation, Bryan, Ohio, a corporation of Ohio Application February 28, 1955, Serial No. 490,968

9 Claims. (Cl. 192-3) This invention relates generally to a control valve for hoists and the like.

It is a primary object of this invention to provide a balanced pneumatic valve capable of performing both throttling and reversing functions in cooperative relation with a reversible pneumatic motor.

It is another object of this invention to provide a balanced valve of special construction wherein a plunger is reciprocably movable in a bore and carries a pair of valve heads spaced relative to the length of the bore to effect selective opening and closing of the ends thereof, said borehaving particularly positioned intake and exhaust ports regulated by movement of said plunger for controlling the operation of a reversible air motor.

It is a further object to provide a control valve of the type aforesaid, wherein actuating means for reciprocating the plunger operatively cooperates with braking means for the reversible air motor, the valve heads and the intake and exhaust ports being precisely located for achieving accurate timing between the operation of the motor and the brake.

It is another object to provide a control valve for an air motor driven hoist, wherein smooth performance is achieved during load lowering by means of a novel porting arrangement serving to dissipate a substantial portion of the energy developed by the descending load through the motor as compressed air rather than through brake means as heat.

It is a still further object to provide a control valve for a reversible air motor of a power driven hoist having brake means operatively associated therewith, wherein selective speed control may be achieved during load lowering by means of (1) the brake, (2) operation of the motor as an energy-consuming pump by compression of exhaust air, and (3) positive motor drive.

it is still another object to provide an air motor driven hoist having spring loaded brake means, wherein low resistance at the controls is offered to the operator through the use of a single balanced control valve, the force due to air pressure at one end of the valve being balanced by an equal and opposite force from air pressure at the other end of the valve, thereby permitting the operator to effect manual operation against the force of the brake spring only.

With these and other objects in view, my invention consists in the construction, arrangement, and combination of the various parts of my control valve for hoists and the like, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in the accompanying drawing, wherein:

Figure l is aside elevational view, partly in perspective, showing a pneumatic hoist embodying the valve construction of the present invention;

Figure 2 is an enlarged vertical sectional view taken substantially as shown at 2-2 on Figure 1, showing the operating control in a neutral position and the motor brakeapplied; v

Figure 3 is a fragmentary vertical sectional view, on

2,823,775 Patented Feb. 18, 1958 an enlarged scale, taken through the right hand end of the hoist of Figure 1;

Figure 4 is a diagrammatic view of the pneumatic motor and related valve porting, showing the cooperation thereof with the valve of this invention;

Figure 5 is a vertical sectional view taken substantially as shown at line 55 on Figure 3, showing the valve in a neutral position;

Figure 6 is a sectional view similar to Figure 5, showing the valve in an operating position for elevating a load;

Figure 7 is a fragmentary view similar to Figure 2 showing the motor brake in an applied position just prior to release;

Figure 8 is another sectional view similar to Figure 5, showing the valve in an operating positon for lowering a load;

Figure 9 is another fragmentary view similar to Figure 7, showing the brake in a disengaged position;

' Figure 10 is a sectional view similar to Figure 8, show ing the valve in operating position for lowering a load at a more rapid rate.

Referring now to the accompanying drawing, I have used the reference numeral 10 to indicate a hoist housing. As indicated diagrammatically in Figure 4, the housing 10 provides a stator 12 and a rotor 14 which is mounted on a motor shaft 16. The rotor 14 is provided with a plurality of vane slots 17 which receive radially slidable vanes 18. The vanes 18 move outwardly in their slots in response to centrifugal force when the rotor 14 is driven, and contactingly engage the inner surface of the stator 12. The rotor 16 is eccentrically positioned relative to the stator 12, in the conventional manner of pneumatic motor constructions.

A sprocket and suitable step-down gearing, not illustrated herein but shown and described in co-pending Shatf application, Serial No. 381,319, filed September 21, 1953, having a common assignee with the present invention, serve to raise and lower a chain 26 as the motor rotor 14 rotates in one direction or the other. A suspending hook 22 and a chain hook 24 are connected in the usual manner with the housing 10 and the chain 20, respectively, as shown in Figure 1.

A cover plate 26 is provided over the right hand end of the housing 10, as viewed in Figure 1. The plate 26 forms a bore 28 therein, in which is positioned a sleeve 30. A pair of plugs 32 (see Figure 5) are screw-threadedly received within the cover plate 26 at opposite ends of the bore 28.

The plate 26 is provided with a compressed air inlet fitting 34 which is adapted to be connected to a suitable source of air under pressure. The inlet 34 communicates with an intake passageway 36, having its end portions 38 and 39 terminating at the opposite ends of the bore 28.

A pair of intake ports 40 and 42 (see Figure 5) communicate through the sleeve 30 with a pair of flow conduits 44 and 46, respectively, as indicated diagrammatically in Figure 4. The conduits 44 and 46 lead to opposite sides of the hoist motor. A pair of exhaust ports 48 and 50 (see Figure 5) communicate through the sleeve 30 with the bore 28. The exhaust ports 48 and 50 are connected by a passageway 52 (see Figure 3) to a cavity 54 in the bottom of the motor stator 12. The cavity 54 communicates with a passageway, not shown, around the stator to a plurality of discharge ports for exhaust to the atmosphere at 57 (see Figure 3), in conventional manner. In addition, primary exhaust ports, indicated diagrammatically in Figure 4 at 56, provide communication from the top of the stator to atmosphere through 57. A similar porting arrangement of this same general type is shown and described in co-pending Shaft application, Serial No. 381,319, filed September 21,

'aseexzvs 1953, having a common assignee with the present invention.

A plunger 60 is slidable in the sleeve 30, and serves to selectively cover the exhaust ports 48 and 50.- Stem portions 62 and 64 extend from the ends of the plunger and terminate in heads 66 and 68. Sealing rings 70 and 72 carried by the heads 66 and 68 contactingly engage the inner wall of sleeve 30.

The bottom of the plunger 60 is provided with rack teeth 74 which mesh with a pinion 76 journaled on a pin 78. A gear sector 80 is mounted on a rock shaft 82 which is connected to a control lever 84. Flexible elements 86 and 88- are suspended from the ends of the lever 84- for rocking the shaft 82.

In Figure 2, I have illustrated a brake drum 90 which is rotatably carried by the motor shaft 16. A pair of brake shoes 92 and 94 of semi-cylindrical form are pivotally secured at their upper ends to a fixed support member 96. A pair of fiber brake liners 98 are carried by the brake : shoes 92 and 94. A resilient loading clamp 100 serves to bias the brake shoes 92 and 94 inwardly toward the brake drum 90 so as to effect tight contacting engagement between the brake liners 98 and the outer surface of the brake drum 90.

An actuator element 102 is carried by the rock shaft 82, and when rotated thereby to the positions illustrated in Figures 7 and 9, serves to engage downwardly extending portions of the brake shoes 92 and 94 for separating them against the biasing force of the clamp 100. The rock shaft 82 is normally centered, as seen in Fig ure 2, by means of the bent lower ends of the brake shoes 92 and 94 pressing against the flat sides of the actuator element v102 due to the force exerted by the resilient loading clamp 100. The arrangement of parts for the center position of the rock shaft 82 is shown in Figure 5.

The practical operation of the hoist valve construction disclosed by the present invention will best be described by reference to Figures through of the drawing. In Figure 5, the plunger 60 is shown in its neutral position slightly off center relative to the ends of the sleeve 30. As shown, the exhaust port 48 is completely closed by the valve plunger 60, and :the exhaust port 50 is substantially fully closed but cracked open a very slight amount. The valve heads 66 and 68 serve to effect closure of both ends of the sleeve 30. A flow of compressed air from the inlet 34 into the sleeve .30 is thereby prevented, and no air is supplied to .the intake ports 40 and 42. It should be noted thatalthough the plunger 60 is disposed slightly off center, the control lever 84 andthe gear sector 80 regulated thereby are balanced in a center position.

In Figure .6, theplunger 68 is shown inashifted position toward the left. This movement .is effected when the operator pulls down -on.the flexible element 86 a slight distance to rotate the rock shaft-82 in a clockwise direction as seen in Figure .6. The pinion 76 is rotated in a counter-clockwise direction,.and .the :plunger :60 .is moved to the left. The head '66 no longer effects closure of the sleeve end, and compressed air flow will enter the sleeve 30 and pass through the intake port 40, and -.c0nduit 44 to the air motor. This will effect forward drive of the motor and a load-secured'to the chain hook 24. will beelevated.

It is important to notezthat load elevation will'occur in this manner before thebrake has lbeenreleased, thereby preventing a risk of load slippage before ssufi'icient power is provided by the air motor.

As clearly'indicated inFigure 4 .of the drawing, v.the' flow pattern is from air-entry at intake port 40 tohirexhaust at port 42, which now acts as .ancxhaustport; The exhaustvport 50 is, of course, now fully open to,complete the exhaust fiowfrom the portal 'The exhaust port 48 is fully-closed. 3

In Figure 7 of the drawing, the corresponding brake operation is shown for comparison with the simultaneous operative positioning of the control valve. As shown, the brake shoes 92 and 94 are about to be released from the brake drum by the actuator element 102, which is rotated by the rock shaft 82. It will be apparent that when the operator pulls theflexible element 86 further downward, the brake will be released, the valve head 66 will be moved to permit maximum air supply to the sleeve 30, and the motor will impart full power for effecting load elevation.

In Figure 8 of the drawing, I have Shown the relationv ship of parts for eifecting load lowering. The operator has drawn the flexible element 88 downwardly a slight amount, effecting rotation of the rock shaft 82 and consequent shifting of the plunger 60 to the right. As shown, both of the valve heads 66 and 68, although moved beyond the centered closure position of the plunger, still eifect flow closure of both ends of the sleeve 30. No air is admitted to the motor. It should be noted that both of the exhaust ports 48 and are fully closed by the valve plunger 60.

As seen in Figure 9 of the drawing, the brake will at this time begin to be released by the actuator element 102, and the load will be permitted to descend slowly under brake speed regulation only. The :descending load now runs the motor as a pump, and the compression of exhaust air dissipates a greater part of the energy developed by the descending load through the motor rather than through the brake as mechanically generated heat. The load may thereby descend at a slow rate of descent by the combined opposing forces exerted by the brake and the motor operating as a pump.

In order to increase the rate of load descent, the operator pulls down on the flexible element 88 so as to further rotate the rock shaft 82 and move the valve plunger further to the right to the position shown in Figure 10. The exhaust port 48 is now slightly cracked open, thereby reducing the resistance or pump elfect of the motor, and permitting a more rapid lowering of the load. As the valve plunger is moved still further toward the right, the exhaust port 48 will be opened more fully, and the lowering speed correspondingly increased as the motor offers still less resistance through compression of exhaust air. When the plunger 60 has been moved sufficientlyfar to the right to permit the valve head 68 to open the end of the sleeve 30, compressed air will be fed to the motor through the intake port -42 thereby driving the load down.

It will be apparentrthat I have providedbythe present invention a balanced control valve .cornbiningthrottling and reversing functions in cooperation witha reversible air motor having mechanicallybraking means associated therewith. Byprecisely locating the valve heads, and the intake and exhaust ports, to achieve accurate timing between the motor and the brake, I provide smooth load elevation without risk of slippage atlow motor power..

Further, efiective speed control is achieved during load lowering throughmechanical braking, exhaust air compression or pump action by the motor, and positive motor drive.

Changesmay be made .in theconstruction and arrangement of the parts of my control valve for hoists and the.

compressed air communicating with said bore at the 0ppo-' site open endsthereoflaplunger reciprocably slidable in said bore and carrying a pair of valve'heads spaced relative to the length of said bore so as to effect selective opening and closing of the ends of said bore when reciprocated, means for reciprocating said plunger in said bore, said body providing a pair of intake ports communicating with said bore and adapted to transmit a flow of compressed air from said bore to the forward and reverse *actuating sides respectively of said reversible air motor, and said body providing a pair of exhaust ports communicating with said bore and through said bore one with a forward and the other with a reverse intake port, said plunger serving to selectively closed and open said exhaust ports when reciprocated, whereby upon movement of said plunger in one direction or the other to open alternatively the ends of said bore and supply compressed air to a corresponding intake port, said exhaust ports will be opened :and closed by said plunger in a selective manner for operation of said air motor as a pump when driven in a reverse direction.

2. In combination with a reversible air motor having a source of compressed air, a valve structure comprising a valve body forming an open-ended bore, said source of compressed air communicating with said bore at the opposite open ends thereof, a plunger reciprocably slidable in said bore and carrying a pair of valve heads spaced relative to the length of said bore so as to effect selective opening and closing of the ends of said bore when reciprocated, means for reciprocating said plunger in said bore, said body providing intake ports communicating with said bore and adapted to transmit a flow of compressed air from said bore to the forward and reverse actuating sides respectively of said reversible air motor, said body providing exhaust ports communicating with said bore and through said bore with corresponding forward and reverse intake ports, said plunger serving to selectively close and open said exhaust ports when reciprocated for effecting throttling of said air motor, and brake means operatively associated with said reversible air motor for effecting speed regulation thereof, said plunger reciproeating means also serving to operatively regulate said brake means, thereby permitting cooperative timing of said air motor and brake means.

3. In combination with a reversible air motor having a source of compressed air, a valve structure comprising a valve body forming an open-ended bore, said source of compressed air communicating with said bore at the opposite open ends thereof, a plunger reciprocably slidable in said bore and carrying a pair of valve heads spaced relative to the length of said bore so as to effect selective opening and closing of the ends of said bore when reciprocated, said body providing intake ports communicating with said bore and adapted to transmit a flow of compressed air from said bore to the forward and reverse actuating sides respectively of said reversible air motor, said body providing exhaust ports communicating with said bore and through said bore with corresponding forward and reverse intake ports, said plunger serving to selectively close and open said exhaust ports when reciprocated for effecting throttling of said air motor, brake means operatively associated with said reversible air motor in normally engaged relation for effecting speed regulation thereof, and actuator means operative both to reciprocate said plunger and to disengage said brake means, thereby permitting cooperative timing of said air motor and brake means.

4. In combination with a reversible air motor having a source of compressed air, a valve structure comprising a valve body forming an open-ended bore, said source of compressed air communicating with said bore at the opposite open ends thereof, a plunger reciprocably slidable in said bore and carrying a pair of valve heads spaced 7 relative to the length of said bore so as to effect selective opening and closing of the ends of said bore when reciprocated, said body providing intake ports communieating with said bore and adapted to transmit a flow of compressed air from said bore to the forward and reverse actuating sides respectively of said reversible air motor, said body providing exhaust ports communicating with said bore and through said bore with corresponding forward and reverse intake ports, said plunger serving to selectively close and open said exhaust ports when reciprocated for effecting throttling of said air motor, brake means operatively associated with said reversible air motor in normally engaged relation for effecting speed regulation thereof, and actuator means operative both to reciprocate said plunger and to disengage said brake means, whereby reciprocation of said plunger to effect air throttling and reversing of said motor also serves to effect predetermined cooperative regulation of the braking of said motor in accurately timed sequence therewith.

5. In combination with a reversible air motor having a source of compressed air, a valve structure comprising a valve body forming an open-ended bore, said source of compressed air communicating with said bore at the opposite open ends thereof, a plunger reciprocably slidable in said bore and carrying a pair of valve heads spaced relative to the length of said bore so as to effect selective opening and closing of the ends of said bore when reciprocated, said body providing a pair of intake ports communicating with said bore and adapted to transmit a flow of compressed air from said bore to the forward and reverse actuating sides respectively of said reversible air motor, said body providing a pair of exhaust ports intermediate said intake ports and communicating with said bore and through said bore one with a forward and the other with a reverse intake port, said plunger serving to selectively close and open said exhaust ports when.

regulation thereof, and actuator means operative both to reciprocate said plunger and to disengage said brake means, whereby reciprocation of said plunger to effect air throttling and reversing of said motor also serves to effect predetermined cooperative regulation of the braking of said motor in accurately timed sequence therewith.

6. In combination with a reversible air motor having a source of compressed air, a valve structure comprising a valve body forming an open-ended bore, said source of compressed air communicating with said bore at the opposite open ends thereof, a plunger reciprocably slidable in said bore and carrying a pair of valve heads spaced relative to the length of said bore so as to effect closure of the ends of said bore when said plunger is disposed in a slightly off-center neutral position, means for reciprocating said plunger in said bore, said body providing a pair of spaced intake ports communicating with said bore and adapted to transmit a flow of compressed air from said bore to the forward and reverse actuating sides respectively of said reversible air motor, said body providing a pair of spaced exhaust ports intermediate said intake ports and communicating with said bore, each of said exhaust ports when open communicating through said bore with a corresponding one of said intake ports, said plunger serving to completely close one of said exhaust ports and crack open the other of said exhaust ports a very slight amount when in neutral position, and serving to selectively close and open said exhaust ports when reciprocated; whereby upon movement of said plunger in one direction from its neutral position to open one end of said bore and supply compressed air to the forward intake port, said closed exhaust port will remain closed and said slightly open exhaust port will be fully opened, thereby providing full forward driving power to said motor; and whereby upon movement of said plunger in the other direction from its neutral position to open the other end of said bore and supply compressed air to the reverse intake port, both of said exhaust ports will first be closed and one of said exhaust ports thereafter progressively opened, thereby 7 effecting variable operation of said motor as a pump to compress exhaust air.

7; In combination with a reversible air motor havinga source of compressedair; a valve structure comprising a valve body forming an open-ended bore, said source ofcompressed air communicating with said bore. at the opposite open endsthereof, a plunger reciprocably slid able insaid bore and carrying apair of valve heads spaced relative to the length of said bore so as to efiect closure of the ends: of saidhere when said plunger is disposed'i'n a slightly off-center neutral position, said body providing a pair of spaced intakeports communieating with said bore and adapted to transmit a How ofcompressed air from said bore to the forward and reverse actuating; sides respectively of said reversible air motor, said body providing a pairof spaced exhaustports intermediate saidintakeports and communicating with said here, each of said exhaust ports.v when open communicating through said" borewith a corresponding one of said intakeports, said plunger serving to completely close one of said exhaust ports andtcrackopen the other of said exhaust ports a very slight amount when in neutral position, and serving to selectively close and open said exhaust ports when reciprocated; whereby upon movement ofv said plunger in one direction from its neutral position to open one-end of said bore and supply compressed air to the forward intake port, said closed exhaust port will: remain closed and said slightly open exhaust. port will be fullyopened, thereby providing full forward driving power'to said' motorgand whereby upon movement; of said. plunger in the other direction from itsneutral position to open the other end of said bore and supply compressed airto the reverse intake port, both of said: exhaust ports will first beclosed' and one of said exhaust: ports thereafter progressively opened, thereby effecting variable. operation of said motor as a pump to compress exhaust air; brake means operatively associated with. said reversible air motor in normally engaged relation for effecting. speed. regulation thereof; and actuator means, operative both to reciprocate said plunger and. to, disengage saidtbrake means, whereby reciprocationofsaidi plunger'to effect air throttling and: reversing? of said motor'also serves to eifect predeterminedcooper-a tive regulation of the braking ofi said=- motor inaccurately" nation with'a reversible air motor of the type having" brake means operativel'y associated therewith, said valve comprisinga balanced reciprocable plunger operative toeflect selective:v porting of compressed air for combined reversing and throttling of said airmotor, and actuator means operative bothtoreciprocate said plunger and to regulate said brake means, whereby speed control may be achieved-selectively'by means ofsaid brake, by operation ofsaid airmotor as-an energy-consuming pump, and by positive drivingoperation of said motor.

9. 111a hoist construction, a control valve in combine tion with areversibleairmotor ofthe type having brake means operatively associated therewith, saidvalve comprising an air pressure balanced reciprocable plunger operativete'efiect selective porting of compressed air for combined' reversing and throttling of said air motor, forward motor operation serving to effect load elevating operation of said-hoist and reverse operation of saidair motor serving to effect load lowering operation of said hoist, and actuator means operative both to reciprocate References Cited in the file of this patent UNITED STATES i PATENTS 583,822 Shem, -N June 1, 1897' 2,4011258' Livers, Mar. 28*;1'946 2,4455'8'5) Shaft u July 20, 1948 2,694,384 Evans Nov. 16, 1954' ,7Q2;0 9 e lQff --.--r--,-- 15;.

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