US3473642A

US3473642A - Speed control device

Info

Publication number: US3473642A
Application number: US648030A
Authority: US
Inventors: William C Lorden; Kennedy Mcconnell; Lucius B Donkle Jr
Original assignee: Interlake Steel Corp
Current assignee: Interlake Steel Corp
Priority date: 1967-06-22
Filing date: 1967-06-22
Publication date: 1969-10-21
Anticipated expiration: 1986-10-21

Description

Oct. 21, 1969 w. c. LORDEN ETAL SPEED CONTROL DEVICE 3 Sheets-Sheet 5 Filed June 22. 1967 5 NM ii WNW.

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ABSTRACT OF T'riE DESCLGSURE A braking device for retarding movement along a conveyor with snubbing action provided by crank means driving reciprocating fluid rams.

This invention relates to the art of braking device for retarding gravity flow and particularly relates to such improved braking devices for use on gravity flow conveyors for retarding the velocity of objects traveling along the conveyors.

Various techniques have been employed for retarding and limiting the speed of objects moving along conveyors. Many of the devices are relatively expensive and many are of limited functional value. Some of them are also provided with several operating parts, certain of which are not as durable as desired. It is, therefore, the principal object of this invention to provide an improved braking device for a conveyor which is functionally adequate, durable in operation and of relatively low cost design utilizing a minimum of working parts and no particularly delicate operating parts.

In order to obtain proper braking action, it is desirable to have a braking device which has a braking force which increases in proportion to the force and speed with which a load traveling on a conveyor contacts it. It is another object of this invention to provide such a braking device.

It is another object of the invention to provide a braking device of the type mentioned which is functionally operative in two directions of travel of a load operating on it.

It is another object of the invention to provide a braking device which is of simple construction so that it is easy to maintain in operation.

In order to accomplish the above objects, it is still another object of the invention to provide a braking device for a conveyor utilizing fluid operative pistons slidably guided in cylinders, the pistons being connected to a crank at least one crank associated with a roller frictionally driven by a load moving on a conveyor whereby the roller causes a cranking action to in turn reciprocate a piston in a cylinder against the pressure of fluid in the cylinder.

It is another object of the invention to provide an improved piston and cylinder design utilizing metered flow of fluid for permitting appropriate reciprocation of the piston in the cylinder.

It is another object of the invention to provide a braking device employing a piston and cylinder of the type mentioned utilizing fluid in the form of liquid and air, whereby the fluid is metered from one side of the piston to the other to allow the proper movement of the pistons and still retain the necessary fluid pressure for proper braking action.

Other objects and advantages of the invention should become apparent upon reference to the accompanying drawings in which:

FIG. 1 shows a perspective view of a conveyor employing braking devices made in accordance with the inven tion;

States Patent 3,473,642 Patented Oct. 21, 1969 FIG. 2 shows a top plan view of a preferred embodiment of braking device of the type indicated in use in FIG. 1;

FIG. 3 shows a sectional view along the line 3-3 of FIG. 2;

FIG. 4 shows a sectional view along the line 44 of FIG. 2; and

FIG. 5 shows a sectional view along the line 55 of FIG. 3.

As particularly indicated in FIG. 1, a gravity conveyor 1 is mounted with a slope which would ordinarily cause the object or load 2 to move down the conveyor 1 in the direction of the arrow 3. The conveyor 1 is of conventional construction having guide rails 4 arranged in pairs with freely rotatable rollers 5 mounted between the pairs of rails 4 with the upper portions of the rollers projecting slightly above the upper surface of the rollers 5. The conveyor is shown in a combination of three roller widths, but it can be of any desired width including rollers of suitable lengths to accommodate the width desired.

Unless arrested or retarded in movement, the load 2 is free to accelerate down the conveyor 1. Oftentimes, the acceleration causes excessive speed resulting in damaging impacts to the load upon its being stopped intermediate or at the end of the conveyor. In order to retard this acceleration and reduce the speed of the load 2 to a desired level, braking devices 6 made according to the invention are suitably positioned at desired intervals along the length of the conveyor 1. Although only two braking devices 6 are indicated on the length of the conveyor 1 shown, the number of braking devices 6 required depends upon the length of the conveyor, its slope, the weight of the loads 2 and the spacing of the braking devices 6 from each other.

Each of the braking devices 6 is provided with a rubber rimmed braking roller 7 which ordinarily projects slightly above the level of the rollers 5 of the conveyor so that a load 2 rolling down the conveyor will have its lower surface contacting these brake rollers 7 and cause their rotation. It is the resistance to rotation of these brake rollers 7 provided by the mechanisms in the braking devices 6 which retards the movement of the load 2 to decrease its speed as the load 2 comes in contact with one or more of the brake rollers 7.

A preferred embodiment of braking device 6 is indicated in FIGS. 2 through 5. Its basic frame consists of two side plates 8 and 9 which extend parallel to each other and are spaced in this parallel position by means of spacer sleeves 10 extending transversely of the side plates 8 and 9. Certain of the spacer sleeves 10 are held assembled to the side plates 8 and 9 by means of bolt fasteners 11 extending through the spacer sleeves 10 and openings in the side plates 8 and 9. In addition, two of the spacers it) are mounted on shafts 12 and 13 which are used to mount the braking devices 6 on the conveyor 1. The shaft 12 extends through slots 8a and 9a in the side plates 8 and 9, respectively and beyond the lateral margins of these side plates 8 and 9. Additional spacer sleeves 14 are provided on these projecting ends of the shaft 12 and these ends extend through openings in the rails 4 and are secured in place by means of threaded fasteners 15 secured on their threaded ends. The threaded fasteners 15 are secured on the shaft 12 in a manner to provide a looseness between the

spacer sleeves

14 and 10 so that the side plates 8 and 9 along with the mechanisms attached thereto can pivot on the shaft 12 to raise or lower the brake rollers 7.

In the vicinity of the shaft 12, there are attached to the outside surfaces of the side plates 8 and 9 adjustment plates 16 and 17. The shaft 12 extends through round openings 13 in these adjustment plates 16 and 17 so that the adjustment plates 16 and 17 cannot shift transversely relative to the shaft 12. Further, the shaft 12,

once positioned in rails 4 is likewise prevented from shifting relative to the rails 4. If it is necessary to adjust the relative height of the brake roller 7, it is necessary to move the side plates 8 and 9 of the braking device 6 up or down relative to the shaft 12 along the slots 8a and 9a until the desired position is reached. During this movement, the side plates 8 and 9 must likewise shift relative to the adjustment plates 16 and 17 because the shafts are in a fixed position relative to these adjustment plates 16 and 17. In order to accommodate this motion, the bolt fasteners 11 are loosened so that the adjustment plates 16 and 17 are free to shift relative to the side plates 8 and 9 as they are guided in slotted openings 19 and 20. When the proper position is reached, the bolt fasteners 11 are tightened to fix the positions of the adjustment plates 16 and 17 relative to the side plates 8 and 9.

At the end of the braking device 6 supported by the shaft 13, the shaft 13 extends through slotted openings 8b and 9b which permit relative movement up and down of the side plates 8 and 9 relative to the shaft 13 as they pivot on the shaft 12. One end 21 of a tension spring 22 is secured around the shaft 13 and its other end 23 is secured around one of the spacer sleeves 10. The normal position of the braking device 6 is one whereby the slots 8b and 9b have their ends clear of the shaft 13 so that there can be relative movement in both directions of the braking device 6 relative to the shaft 13. As a load 2 comes down the conveyor 1, enough free movement against the pressure of the spring 22 must be provided so that the upper periphery of the brake roller 7 can lower slightly to properly contact the lower surface of the load 2. The slotted openings 8b and 9b should be long enough so that there is sufiicient travel in both directions that the brake roller 7 can return to its raised position after the load 2 has passed over it. The force of the spring 22 must be sufiicient to strongly urge the brake roller 7 against the undersurface of the load 2 and thereby minimize slippage between the brake roller 7 and the load 2.

To provide relative continuity of support along the conveyor 1, auxiliary rollers 25 are suitably journaled on shafts 26 and these rollers 25 are positioned at levels approximately equal to the levels of the rollers of the conveyor 1.

The brake roller 7 is mounted on a shaft 27 which is suitably journaled in bearings 28 secured to the side plates 8 and 9. The shaft 27 is secured at one end 27a by means of a pin 27b to a crank arm 29. The other end 270 of the shaft 27 is secured by means of a pin 27d to another crank 24. The angular positions of the cranks 24 and 29 are approximately 90 relative to each other.

The brake roller 7 is indicated as an annulus 7a mounted on a central portion 27e of the shaft 27. The shaft 27 has an enlarged integral flange 32 which carries bolts 322 connected through the annulus 7a and a side plate 31 to clamp the annulus 7a to the flange 32 and retain it in a fixed position on the shaft 27.

The crank 24 is pivoted on a pin 33 to the outer end 34 of a piston rod 35 having an inner end secured to a piston 36 which is slidable along the interior surface 37 of a cylinder 38. The cylinder 38 is appropriately sealed at both ends so that fluid contained within the cylinder 38 is prevented from leaking out. As the crank arm 24 rotates with the shaft 27 driven by the brake roller 7 the piston rod 35 reciprocates in and out of the cylinder 38 to cause the piston 36 to reciprocate back and forth along the interior surface 37 of the cylinder 38. The piston is provided with a small opening 39 extending entirely through it from one end to the other. As the piston 36 reciprocates back and forth, fluid is forced through the opening 39 from one side to the other depending upon which direction the piston 36 is traveling.

The inner end 38a of the cylinder 38 is pivoted on a pin 38b journaled in a bracket 380 which is secured to the side plate 9. The pivotal arrangement permits the cylinder 38 to reciprocate angularly on the pivot pin 3817 as the crank arm 34 is rotated with the shaft 27 In a similar manner the crank arm 29 is pivoted on a pin 40 to the outer end 41 of a piston rod 42 having an inner end connected to a piston identical to the piston 36 in a cylinder 43 identical to cylinder 38. Similarly, this cylinder 43 has an inner end 43a journaled on a pin 43b to a bracket 430 secured to the side plate 8 to provide a pivotal motion of the cylinder 43 on the pin 43b to permit angular reciprocation of the cylinder 43 as the crank arm 29 rotates with the shaft 27.

In operation, as a load 2 engages the brake roller 7, it rotates to cause the shaft 27 to rotate and thereby rotate the crank arms 24 and 29 to cause out of phase reciprocation of the

piston rods

35 and 42 and their respective pistons. For example, piston 36 will move longitudinally along the cylinder 38. As it does, fluid will tend to be compressed in the direction of travel of the piston 36 and thereby forced through the opening 39 in the piston 36 in a direction opposite to the travel of the piston 36. The cross sectional size of the opening 39 will determine how quickly the fluid can pass through it. If nothing more than air is contained within the cylinder 38, it is possible to obtain somewhat satisfactory operation because the opening 39 can be made of a size to retard the flow of air through it sufiiciently that the brake roller 7 is retarded in its motion as the crank arms 24 and 29 rotate. A more desirable condition is to have a two-stage cushioning effect whereby the initial resistance to rotation of the brake roller 7 is less than the resistance thereafter. In order to accomplish this, the cylinder 38 is partially filled to a level indicated at 44 with liquid. such as oil. As indicated, the level of the oil at 44 is below the level of the opening 39 in the piston 36. Therefore, initially, movement of the piston 36 to the left, as indicated in FIG. 3, will cause the air to exit through the opening 39 in the direction to the right, as indicated in FIG. 3. As the piston 36 moves to the left, the oil level rises so that oil will be raised to the level of the opening 39 and the oil along with the air will tend to be urged through the opening 39. As movement of the piston 56 continues to the left, there will be more tendency for greater amounts of the oil to pass through the opening 39 because the ratio of oil to air on the left side of the piston 36 will be increased. As the oil begins to flow through the opening 39, because of its greater viscosity than air, the resistance to movement of the piston 36 will increase and provide a greater resistance to rotation of the brake roller 7 to begin the second stage of resistance to rotation mentioned. Upon reverse movement of the piston 36, the same type of action occurs, the oil level on the right side of the piston 36 is below that of the opening 39 and air will be initially exhausted to the left of the opening 39 until the oil level rises in the right chamber of the cylinder 38 and begins to flow alone or with the air through the opening 39.

As rotation of the brake roller 7 continues, the oil undoubtedly becomes churned in the cylinder 39 so that there is a continuous flow of oil and air back and forth through the opening 39 to provide a somewhat constant resistance to rotation of the brake roller 7.

Whereas one cylinder 38 and its components might be considered acceptable for operation, it is preferred that at least two

cylinders

38 and 43 be employed with their crank arms 24 and 29 at approximately out of phase angularly with each other. The reason for this is that the end points, as for example when the

piston rods

35 and 42 are either fully extended or fully retracted and in longitudinal alignment with their crank arms 24 and 29. respectively, these represent turnaround points where. with only one cylinder, these would be points of theoretical zero resistance to rotation of the brake roller 7. By

having the out of phase relationship of the crank arms 24 and 29, there is always a crank arm positioned beyond one of these end points with the result that there is always a certain amount of resistance to the rotation of the brake roller 7. Other out of phase angular relationships can be employed. A 90 relationship seems to be desirable because it is midway between the end points which are 180 from each other.

In order to assure proper two-stage operation of the

cylinders

38 and 43, it is desirable to have an initial level 44 of the oil below the level of the orifice 39, as indicated in FIG. 3. In this manner, the first impact of a load 2 on the brake roller 7 is resisted by a cushion of air, rather than by the oil. The resistance is less at this time because the air can travel in higher volume through the orifice 39. After the load has been retarded a bit, then it is proper to provide a higher braking force which is introduced by the flow of the oil. In this manner, the braking action is somewhat gradual and provides a very uniform and desirable slowing-down of the load 2 Without injurious abrupt jolting.

What has been shown and described is a preferred embodiment of the invention and is one which can be produced economically with relatively inexpensive components of durability which are capable of operating for long periods of time without any significant adjustment or replacement of parts. The

cylinders

38 and 43 are relatively inexpensive and of a type readily purchased for use as a door check, commonly found on storm doors and the like for homes. Further, it has been found that the range of braking action can be varied by varying the cross sectional size of the opening 39 in the piston 36 to provide faster or slower bleeding of the air and liquid or other fluid from one side of the piston to the other. Ordinarily, for any conveyor system, it is known in advance as to the weight range of the loads 2 involved and, so, cylinders having a pre-calculated size of opening or orifice 39 can be used. If the range of load weights is changed, it is only necessary to replace the relatively

low cost cylinders

33 and 43 with others having the required size of orifice 39.

We claim:

1. A Speed control device comprising, a frame, a roller rotatably mounted on said frame, and snubbed crank means in driven connection with the roller to snub rotation of the roller, said snubbed crank means being in the form or" a crank driven by the roller, said crank being in driving connection to a fluid ram which snub movement of the crank by fluid pressure buildup in the ram in opposition to the driving force of the crank, said fluid ram comprising a piston slidably mounted for reciprocating movement in a cylinder having fluid therein for reacting against the piston, and metering means in the fluid ram for metering fluid from one end of the cylinder to the other against fluid pressure buildup in the cylinder caused by movement of the piston in the cylinder in response to driving movement of the crank, said metering means being a port extending through the piston from one end to the other relative to the direction of movement of the piston in the cylinder, said cylinder being filled with a combination of two fluids both in communication with said metering means, one fluid having a low viscosity and the other having a high viscosity.

2. A speed control device comprising, a frame, a roller rotatably mounted on said frame, and snubbed crank means in driven connection with the roller to snub rotation of the roller, said snubbed crank means being in the form of a crank driven by the roller, said crank being in driving connection to a fluid ram which snubs movement of the crank by fluid pressure buildup in the ram in opposition to the driving force of the crank, said fluid ram comprising a piston slidably mounted for reciprocating movement in a cylinder having fluid therein for reacting against the piston, and metering means in the fluid ram for metering fluid from one end of the cylinder to the other against fluid pressure buildup in the cylinder caused by movement of the piston in the cylinder in response to driving movement of the crank, said metering means being a port extending through the piston from one end to the other relative to the direction of movement of the piston in the cylinder, said cylinder being filled with a combination of two fluids both in communication with said metering means, one fluid being a gas and the other being a liquid.

3. A speed control device comprising, a frame, a roller rotatably mounted on said frame, and snubbed crank means in driven connection with the roller to snub rotation of the roller, said snubbed crank means being in the form of a crank driven by the roller, said crank being in driving connection to a fluid ram which snubs movement of the crank by fluid pressure buildup in the ram :in opposition to the driving force of the crank, said fluid ram comprising a piston slidably mounted for reciprocating movement in a cylinder having fluid therein for reacting against the piston, and metering means in the fluid ram for metering fluid from one end of the cylinder to the other against fluid pressure buildup in the cylinder caused by movement of the piston in the. cylinder in response to driving movement of the crank, said metering means being a port extending through the piston from one end to the other relative to the direction of movement of the piston in the cylinder, said cylinder being filled with a combination of two fluids both in communication with said metering means, one fluid being lighter in weight and lower in viscosity than the other, and said cylinder ordinarily being positioned with the metering means through the piston being above the static level of the heavier fluid.

4. A speed control device comprising, a frame, a roller rotatably mounted on said frame, and snubbed crank means in driven journalled connection with the roller to snub rotation of the roller, said snubbed crank means being in the form of a crank driven by the roller, said crank being in driven connection to a fluid ram which snubs movement of the crank by fluid pressure buildup in the ram in opposition to the driving force of the crank, said snubbed crank means having two crank arms positioned angularly out of phase with each other and each connected to separate fluid rams, said out of phase relationship insuring continuous snubbing action through a full cycle of rotation of the roller, said fluid ram comprising a piston slidably mounted for reciprocating movement in a cylinder having fluid therein for reacting against the piston, and metering means in the fluid ram for metering fluid from one end of the cylinder to the other against fluid pressure buildup in the cylinder caused by movement of the piston in the cylinder in response to driving movement of the crank, said metering means being a port extending through the piston from one end to the other relative to the direction of movement of the piston in the cylinder, said cylinder being filled with a combination of two fluids both in communication with said metering means, one fluid being lighter in weight and lower in viscosity than the other, and said cylinder ordinarily being positioned with the metering means through the piston being above the static level of the heavier fluid, said frame having mounting means for adjustably locating the roller in mounted position on a conveyor.

References Cited UNITED STATES PATENTS 3,376,965 4/1968 Tregoning et a1. 193-35 ANDRES H. NIELSEN, Primary Examiner