US3340977A - Rotary supports - Google Patents

Description

Sept. 12, 1967 H. COWAN ROTARY SUPPORTS Z5 SheetseSheet l Filed June 10, 1966 Sept. 12, 1967 H. CQWAN ROTARY SUPPORTS 3 Sheets-Sheet 2 Filed June 10, 1966 Sept. 12, 1967 Y H. COWAN 3,340,977

ROTARY SUPPORTS Filed June 10, 1966 5 Sheets-Sheet 3 United States Patent 3,340,977 ROTARY SUPPORTS Henry Cowan, Lillington, Leamington Spa, England, as-

signor to The Iso-Speedic Company Limited, Warwick, England, a British company Filed June 10, 1966, Ser. No. 556,649 6 Claims. (Cl. 193-37) In my Patent No. 3,245,510, assigned to the assignees hereof, there are disclosed two examples of mechanical goods handling systems of the kind in which a carrier such as a pallet or truck :runs under gravity down an inclined path along which it is guided. The guidance may be provided by wheels on the carrier running on guide rails, or the carrier may run over and be transversely located with respect to a series of rollers which rotate about fixed axes.

In accordance with the invention described in the earlier specification a wheel or roller -for supporting a carrier of such a system has a peripheral portion which rotates with the wheel or roller and surrounds a chamber containing a gear pump in the form of two gear wheels one of which is located on a fixed axis and the other of which is carried by the wheel or roller and rotates when the wheel or roller rot-ates to drive the pump. The arrangement is such that hydraulic fluid in the chamber is continuously circulated by the pump around a closed circuit and the resistance of the fluid to the action of the pump provides a continuous braking effect. Little resistance to rotation of the wheel or roller is provided at low rotational speeds but as the speed of the carrier increases, the resistance increases accordingly, until the component of gravitational force down the inclined path is just balanced.

The system may be used with loads of appreciably different weights and one disadvantage with the prior system is that the limiting velocity will be excessively high for high weights and excessively low for low weights.

In accordance with the present invention the closed circuit around which the hydraulic fluid is pumped in a wheel or roller of the kind protected by the earlier application contains a throttle valve which is automatically actuated by increase in pressure on the outlet side of the pump so that as the speed of rotation of the wheel or roller increases the closed circuit is automatic-ally restricted to provide a greater resistance.

This arrangement provides in effect a self compensating effect so that the limiting velocity will have a reasonable value for both heavy and light loads.

The throttle valve preferably comprises a closure member which is urged by the pressure of the hydraulic fluid in the circuit to move against a resilient loading towards a seating to restrict the effective cross-sectional area of the circuit. The closure member may be, for example, a ball closure member which moves within a tubular conduit forming part of the circuit against the action of a helically coiled compression spring towards an annular seating provided inside the conduit. The fluid flowing through the conduit then has to flow around the ball through the annular space between the ball and the inner wall of the conduit. If the conduit tapers in the direction of flow an infinitely variable restriction is provided as the pressure of the fluid varies. If all the fluid flowing around the closed circuit has to pass through the conduit, the position must not be reached in which there is no annular clearance left between the ball and the inner wall of the tubular conduit and for this purpose an abutment, for an example -an adjustable screw stop, may be provided to limit movement of the ball towards the narrower end of the conduit.

It is not necessary for all the fluid which passes around the hydraulic circuit to pass through the throttle valve and the circuit may be provided by at least twosubcir- Ice cuits in parallel with one another, only one of the subcircuits containing the throttle valve. This is a simpler arrangement and it is not then necessary for the throttle valve to be prevented from closing fully and it can form a straight shut-off valve which, when the pressure on the outlet side of the pump rises to a predetermined value, throttles the flow in the first subcircuit completely. All the fluid will then have to flow through the other subcircuit the effective cross-section of which is necessarily smaller than that of the two subcircuits together. The arrangement will then have only two settings one 'for low rotational speeds in which the fluid flows through both subcircuits and the other, to which there is automatic changeover when the speed or rotation of the wheel or roller reaches and exceeds a predetermined value, in which the fluid can only flow through the unrestricted other subcircuit. I

When the two subcircuits are provided in parallel in this way the shut-off valve may again be in the form of spherical ball which is movable against the action of the helically coiled compression spring in a tubular conduit, which forms one of the subcircuits. The ball however may now move to and fro in a cylindrical portion of the tubular conduit and a seating is provided on which the ball seats and closes the conduit when the pressure is sufficient for the ball to move against the action of the spring to an appropriate extent. In this case the seating may simply be an annular shoulder at the end of the cylindrical portion of the tubular conduit.

Alternatively the throttle valve may be a flap valve which moves against spring loading between fully open and fully close-d positions. Irrespective of the form of the throttle valve, when there are two subcircuits, the second subcircuit may be provided by clearances between at least one of the gear wheels and the wall of the chamber.

The gear pump may take a number of different forms. It may include two gear wheels in the form of externally toothed pinions which mesh with one another such as for example in the two examples illustrated in our earlier specification. Alternatively one of the gear wheels may be internally toothed and the other externally toothed so that they co-operate with a gyral action.

Two examples of systems incorporating wheels and rollers constructed in accordance with the invention are illustrated in the accompanying drawings in which:

FIGURE 1 is a perspective view of one system;

FIGURE 2 is a front elevation of a second system;

FIGURE 3 is a section, of a roller used in the first system, taken on the line IIIIII in FIGURE 4;

FIGURE 4 is a section taken on the line IVIV in FIGURE 3;

FIGURE 5 is a section taken on the line V-V in FIGURE 3;

FIGURE 6 is an enlargement of part of FIGURE 5;

FIGURE 7 is a graph indicating the relationship between speed and resistance in respect of a wheel or roller constructed in accordance with the invention;

FIGURE 8 is a section, through a wheel of the second system, taken on the line VIII-VIII in FIGURE 9;

FIGURE 9 is a section taken on the line IX-IX in FIGURE 8;

FIGURE 10 is a section taken on the line X-X in FIGURE 9, that is the same line as that on which the section of FIGURE 8 is taken but looking in the other direction; and

FIGURE 11 is a section taken on the curved line XIXI in FIGURE 8.

The system illustrated in FIGURES 1 and 3 to 6 inclusive is an improvement of that illustrated in FIG- URES I to III of the previously mentioned specification. The system comprises one or more flat rectangular plywood pallets 12 on which boxes or crates 13 can be stacked and which run down an inclined track over three rows of rollers 14. The rollers 14 are freely rotatable about fixed horizontal axes and are mounted between adjacent pairs of beams 15 of a supporting framework. Lateral guide rollers 16 are mounted at intervals along the outer beams 15 and are rotatable about fixed vertical axes. The rollers 16 are positioned so that they engage the sides of a pallet 12 and prevent the pallet from being displaced laterally on the track.

At intervals along the tracks a roller 14 of the central row of rollers is replaced by a special brake roller 17. Each brake roller 17 is rotatable on an axle 18 which is rigidly and non-rotatably supported in a bracket 19 carried by a part of the framework.

As shown in FIGURES 3 to 6, the roller 17 has a body 20 which is rotatably mounted by means of a needle bearing 21 on a hub 22 formed integrally with the axle 18. One end face of the roller consists of a removable cover plate 23 which is bolted to a peripheral portion 24 of the body 20 by means of three bolts 25. The cover plate 23 together with the peripheral portion 24 form the casing for a gear pump mounted in a chamber 26. The gear pump comprises a sun wheel 27 rigidly fixed on the hub 22 and a planet wheel 28 which meshes with the sun wheel 27 and which is freely rotatable on a pin 29 that is a tight leakproof fit in a bore in the body 20. The sun wheel 27 and planet wheel 28 run with small axial and radial clearances adjacent the inner wall of the pump chamber 26 but the parts of the chamber 26 on each side of the mesh of the sun and planet wheels are interconnected by a narrow passage 30 extending around the sun wheel 27 and formed between a groove in the end face of the peripheral portion 24 and the cover plate 23. The body 20 is surrounded by a solid rubber tyre 31 which stands a little proud of the other rollers 14 in the centre row of rollers.

So far described the system is identical with the first example described in the earlier specification. The Present improvement lies in the provision of a second passage interconnecting the parts of the chamber 26 on the two sides of the mesh between the wheels 27 and 28 in parallel with the passage 30. This second passage is provided by bores 32 and 33 in the inner wall of the chamber 26 and by a cross blind bore 34 interconnecting the inner ends of the bores 32 and 33. The open end of the bore 34 is sealed with a screw plug 35. The bore 33 has an enlarged entrance in which a sleeve 36 having an internal shoulder 37 is a tight push fit. The sleeve 36 projects into the pump chamber 26 far enough for a ball 38 to be contained within the sleeve 36 by the cover plate 23. The sleeve 36 forms the housing of a throtle valve of which the ball 38 is the closure member, the shoulder 37 is the seating, and a helically coiled compression spring 39 provides a loading urging the ball 38 away from its seating. The chamber 26 and passages are filled with oil, except perhaps for a small air bubble to allow for expansion.

In operation as the pallet 12 runs down the track, it accelerates freely while not in contact with a roller 17 but as its underneath frictionally engages the rubber tyre 31 of each roller 17 in turn the roller is caused to rotate. As this happens the body 20 carries the planet wheel 28 around with it and the stationary sun wheel 27 causes the planet wheel 28 to rotate and build up a pressure differential between the oil in the parts of the chamber 26 on the two sides of the mesh between the wheels. At low rotational speeds this pressure differential is insuflicient to overcome the loading of the spring 39 and close the throtle valve so that the oil is pumped both through a first subcircuit provided by the passage 30 and through a second subcircuit provided by the sleeve 36, and the bores 33, 34 and 32. These subcircuits provide a resistance to the pumping action of the gear pump so that the roller 17 is braked. The resistance increases as the speed of rotation increases so that for a given weight of pallet and load, a given inclination of track, and a given viscosity of oil, the roller 17 will accelerate to a terminal velocity which will not be exceeded. The pallet will then be stabilised at the terminal velocity as it engages and runs over each roller 17 in turn. This corresponds to the part A of the curve of FIGURE 7.

In the event of the weight of the load and pallet exceeding a certain value, the stable condition will not arise before the pressure differential is suflicient to move the ball 38 against its spring 39 and seat the ball on its seating 37 so that the second subcircuit is closed and the only path for the oil to flow is around the first subcircuit formed by the passage 30. This introduces a sudden additional resistance in the oil flow, and increases the resistance characteristics of the brake as indicated by the part B of the curve of FIGURE 7. Subsequent increase in rotation speeds increases the effective resistance of the passage 30 to the flow of oil until a stable condition along the part C of the curve of FIGURE 7 is reached. In this way light loads are able to reach a reasonable velocity but appreciably heavier loads are not able to reach an excessive velocity, the change over in the resistance characteristics of the brake occuring automatically in dependence upon the parameters involved.

The gear pump is accessible for servicing or for replacement of the oil by one having a different viscosity, by undoing and removing the bolts 25 and removing the cover plate 23. The oil is securely retained within the gear pump and passages by a static O sealing ring 40 between the cover plate 2.3 and the peripheral portion 24 and by a sealing ring 41 of a channel section positioned between the relatively rotating hub 22 and body 20 with the open face of the ring towards the oil pressure in the pump. The oil in the pump lubricates the needle bearing 21.

The slopes of the portions A and C in the FIGURE 7 curve and the position of the portion B can be altered by changing the oil for one of a different viscosity, and changing the characteristics of the spring 39 respectively.

In practice it may be possible to eliminate the passage 30 entirely and then arrange for the ball 38 to meet a stop before completely closing the passage through the sleeve 36, to provide the high resistance characteristic of the brake. Alternatively, the high resistance characteristics maybe provided entirely by the inefficiency of the pump, that is to use the necessary small clearances between the inner walls of the pump chamber 26 and the peripheral and axial portions of the wheels 27 and 28 for leakage of the oil from the high pressure to the low pressure side of the pump when the throttle valve closes the sleeve 36.

The roller shown in FIGURES 3 to 6 may equally Well be used as a pallet wheel, instead of as a stationary roller, of the alternative type of system in which the pallet runs on wheels down a rigid track.

The second system illustrated in FIGURES 2 and 8 to 11 inclusive is of this alternative type and comprises one or more pallets 42 for carrying goods 43-, each of the pallets being supported at its corners by wheels 44 which run on grooved rails 45 of an inclined track. Each wheel is supported by means of a U-shaped bracket 46.

A wheel is shown in more detail in FIGURES 8 to 11. The wheel is mounted on a shaft 47 which has projecting tongues 48 at each end for nonrotatably locating the shaft 47 between the arms of a U-shaped bracket 46. The wheel body is formed in two parts, a disc 49 which is surrounded by a solid rubber tyre 50, and a cup 51. The cup 51 has a flange 52 which is bolted to the disc 49' by cap screws 53 and is accurately located relatively to the disc by means of a pair of dowels 54. The body is rotatably mounted on the shaft 47 by means of needle bearings 55 and 56 and the shaft is sealed by O sealing rings 57. The two parts of the body are sealed by an O sealing ring 58. A sun wheel 59 is rigidly fixed on the shaft 47 by means of a cross pin 60 and co-operates with an internally toothed rotor 61. The rotor 61, which has one tooth more than the sun wheel 59 is rotatably mounted in a cylindrical bore 62 within the cup 51, the axis of the bore 62 being eccentric to the axis of the shaft 47.

Two kidney shaped slots 63 and 64 are formed in the end face of the disc 49 in register with a pump chamber 65 formed by the clearance between the sun Wheel 59 and the rotor 61. The slots 63 and 64 are interconnected 'by a first subcircuit including bores 66 and 67 which are drilled through the disc 49 and the outer ends of which are sealed by screw plugs 68. The inner ends of the bores 66 and 67 are themselves interconnected 'by a cross bore 69 the outer end of which is sealed by a screwed plug 70.

Each of the slots 63 and 64 is also fitted with a leaf spring 71 one end of which is located by means of a screw 72 and the other end 73 of which forms a closure member overlying the entrance to the corresponding bore 66 or 67 but is held away from the bore to an extent limited by a screw 74 by means of a helically coiled compression spring 75 which takes its reaction from the end of the corresponding plug screw 68. The chamber 65 and bores 66, 67 and 69 are filled with oil, again except perhaps for a small air bubble.

In operation as the wheel is rotated, in this case in either direction, as a pallet 42 runs down the track 45, the rotor 61 is caused by the camming action of the bore 62 and the teeth of the fixed sun wheel 59 to gyrate around the sun wheel, moving by one tooth relatively to the sun wheel 59 upon each revolution of the wheel. The pump itself operates in a conventional fashion and the slots 63 and 64 are angularly related to the eccentricity of the bore 62 such that depending on the direction of rotation one of the slots 63 and 64 always experiences suction and the other port pressure. Consequently at low rotational speeds oil flows continually from the pump chamber 65 through the first subcircuit provided by the bores 66, 67 and 69 back to the chamber 65. The circuit provides a resistance to the flow and as with the first example, as the speed of rotation of the wheel increases an equilibrium condition is reached in which a terminal velocity is established. This corresponds to the portion A on the curve of FIGURE 7.

If the weight of the pallet and load is sufliciently great, the differential oil pressure between the pressure and suction slots will increase sufiiciently to overcome the loading of the spring 75 corresponding to the pressure slot before a terminal velocity is reached. If this happens the part 73 of the leaf spring 71 in the pressure slot will move against the action of the spring and close the entrance to the corresponding bore 66 or 67 and the oil will be forced to the pallet 42 to be provided with a gear pump and any one, two ,or three of the wheels may be free running. Indeed, the illustrated wheel can be converted to a simple free running wheel by removing the rotor 61.

I claim:

1. In a mechanical goods handling system of the kind comprising an inclined track, a goods carrier adapted to move under gravity down said track, and means supporting said goods carrier during said movement; the improved support means which comprises a rotary member rotatably carried by one and peripherally engaging the other of said carrier and said track, said rotary member comprising a hollow portion which turns therewith, means defining with said hollow portion a chamber, first and second meshing gear wheels within said chamber which form with said chamber a gear pump, said first gear wheel being carried on a fixed axis and said second gear wheel being carried by said rotary member and mounted to rotate when said rotary member rotates whereby said pump is driven, means defining a closed circuit connecting the output side of said pump to the input side of said pump, a throttle valve within said circuit and adapted to be automatically actuated by increase in pressure on the outlet side of said pump, and a mass of hydraulic fluid substantially filling said pump chamber and circuit for continuous circulation through said circuit by said pump whereby the resistance of said fluid to the leak from the high pressure side of the pump to the low pressure side through a second subcircuit formed by the clearances 76 between the sun wheel 59 and the rotor 61 at their point of mesh, and between the axial end faces of the sun wheel and rotor and the inner walls of the chamber 65. The resistance characteristics of the wheel will then automatically pass through the part B of the curve of FIGURE 7 to the part C.

An abutment maybe provided in each of the bores 66 and 67 to limit the movement of the part 73 against the spring 75 so that a small leakage through the first subcircuit remains even when the wheel is working on part C of the curve of FIGURE 7.

The wheel of FIGURES 8 to 11 may alternatively be used as a stationary roller in a system of the kind illustrated in FIGURE 1, in which case the tongues 48 at the ends of the shaft 47 will be mounted in the fixed framework.

It is not of course necessary for all the four wheels of action of said pump provides a. braking effect and as the speed of rotation of said rotary member increases said closed circuit is automatically restricted by actuation of said throttle valve to provide a greater resistance.

2. The invention according to claim 1, wherein said throttle valve comprises a seating, a closure member adapted to be urged by the pressure of said hydraulic fluid from the outlet side of said pump to move towards said seating, and means of resiliently urging said closure member away from said seating.

3. The invention according to claim 2, further comprising a tubular conduit forming part of said circuit and wherein said closure member is a ball moving in said tubular conduit and said last named means is a helically coiled compression spring.

4. The invention according to claim 2, wherein said throttle valve is a flap valve.

5. The invention according to claim 1, wherein said circuit consists of at least first and second subcircuits arranged in parallel with one another, said first subcircuit incorporating said throttle valve which is adapted upon rise in the fluid pressure on said outlet side of said pump to a predetermined value to close said first subcircuit completely whereby all said fluid has to flow through said second subcircuit.

6. The invention according to claim 5, wherein said second subcircuit is provided by clearances between at least one of said gear wheels and a part of said chamber.

References Cited UNITED STATES PATENTS 2,618,370 11/1952. Orwin.

3,095,956 7/1963 McGill.

3,180,472 4/ 1965 Isacsson 19337 3,245,510 4/ 1966 Cowan 19335 EVON C. BLUNK, Primary Examiner. ANDRES H. NIELSEN, Examiner.

Claims (1)

1. IN A MECHANICAL GOODS HANDLING SYSTEM OF THE KIND COMPRISING AN INCLINED TRACK, A GOODS CARRIER ADAPTED TO MOVE UNDER GRAVITY DOWN SAID TRACK, AND MEANS SUPPORTING SAID GOODS CARRIER DURING SAID MOVEMENT; THE IMPROVED SUPPORT MEANS WHICH COMPRISES A ROTARY MEMBER ROTATABLY CARRIED BY ONE AND PERIPHERY ENGAGING THE OTHER OF SAID CARRIER AND SAID TRACK, SAID ROTARY MEMBER COMPRISING A HOLLOW PORTION WHICH TURNS THEREWITH, MEANS DEFINING WITH SAID HOLLOW PORTION A CHAMBER, FIRST AND SECOND MESHING GEAR WHEELS WITHIN SAID CHAMBER WHICH FORM WITH SAID CHAMBER A GEAR PUMP, SAID FIRST GEAR WHEEL BEING CARRIED ON A FIXED AXIS AND SAID SECOND GEAR WHEEL BEING CARRIED BY SAID ROTARY MEMBER AND MOUNTED TO ROTATE WHEN SAID ROTARY MEMBER ROTATES WHEREBY SAID PUMP IS DRIVEN, MEANS DEFINING A CLOSED CIRCUIT CONNECTING THE OUTPUT SIDE OF SAID PUMP TO THE INPUT SIDE SAID PUMP, A THROTTLE VALVE WITHIN SAID CIRCUIT AND ADAPTED TO BE AUTOMATICALLY ACTUATED BY INCREASE IN PRESSURE ON THE OUTLET SIDE OF SAID PUMP, AND A MASS OF HYDRAULIC FLUID SUBSTANTIALLY FILLING SAID PUMP CHAMBER AND CIRCUIT FOR CONTINUOUS CIRCULATION THROUGH SAID CIRCUIT BY SAID PUMP WHEREBY THE RESISTANCE OF SAID FLUID TO THE ACTION OF SAID PUMP PROVIDES A BRAKING EFFECT AND AS THE SPEED OF ROTATION OF SAID ROTARY MEMBER INCREASES SAID CLOSED CIRCUIT IS AUTOMATICALLY RESTRICTED BY ACTUATION OF SAID THROTTLE VALVE TO PROVIDE A GREATER RESISTANCE.

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