US2279364A - Compressed air internsifier - Google Patents

Description

April 14, 1942- G. N. CADBURY 2,279,364

COMPRESSED AIR INTENS IFIER April 14., 1942- G. N. CADBURY 2,279,364

COMPRESSED AIR INTENSIFIER Filed July 24, 1940 2 Sheets-Sheet 2 L ai N Patented Apr. 14, 1942 COMPRESSED' AIR INTENSIFIER George Norman Cadbury, West Bromwich, England, assignor to E. M. B. Company Limited, West Bromwich, England Application July 24, 1940, Serial No. 347,323 In Great Britain September 1, 1939 (Cl. E30-52) '7 Claims.

This invention has for its object to provide an improved compressed-air intensifier for use with die casting and other machines.

The invention comprises the combination of a ram having a pair of parts of different diameters, a cylinder in which the ram is arranged and which is provided with two parts of appropriately different diameters for accommodating the ram parts, the ram and cylinder being capable of relative sliding movement under the action of compressed air in the direction for compressing air in the cylinder part of smaller diameter, admission and exhaust valve means for controlling the flow of air to and from the larger part of the cylinder, a non-return valve past which air can flow to the smaller part of the cylinder, and delivery and exhaust valve means for controlling communication between the smaller part of the cylinder, the apparatus to be operated, and an outlet therefrom to atmosphere.

In the accompanying sheets of explanatory drawings- Figure 1 is a diagrammatic sectional elevation of a compressed-air intensifier constructed in accordance with the invention.

Figure 2 is a similar View to Figure 1 illustrating a modified form of the invention.

Figure 3 is a part sectional elevation of one of the valves shown in Figure 2.

In carrying the invention into effect as shown in Figure 1, I employ a slidable ram having a pair of coaxial parts a, b, of different diameters, and I arrange this ram in a stationary cylinder having two parts c, d, of appropriately different internal diameters for slidably accommodating the two parts of the ram.

For actuating the ram a, b, compressed air from a supply pipe or passage f is admitted to the interior of the larger cylinder part c through an opening g in one end, communication between this opening and the supply pipe or passage being controlled by a valve h. The other end of the cylinder part c is formed with an opening or openings i for atmospheric air.

In the part c of the cylinder I may arrange a helical spring e which acts on the ram part a and serves to effect or assist the return of the ram to its initial position after it has been actuated.

As shown the valve h is arranged in a chest j which communicates at one end with the supply pipe or passage f, and at the other end with the opening g in the cylinder part c, the valve being adapted to co-operate with a seating in the chest sage enlargement s.

for interrupting communication between the supply pipe or passage and the said opening` The chest j is also provided with an outlet k which is situated between the valve h and the cylinder part c, and through which air can be released from the said cylinder part under the control of another valve m situated in the chest.

The valves h, m are of the poppet type and are provided with depending stems n, o, which at their outer ends project from the valve chest j, so that the valves can be alternatively actuated by a single operating lever p pivoted to the chest at a position between the projecting ends of the valve stems. Instead of separate inlet and outlet valves a single equivalent valve may be used. The lever p is operable by the attendant either directly or through any intermediate means, or in some cases it may be actuated automatically in response to movements of the machine to which air is supplied from the intensifier.

The pipe or passage f also serves to supply compressed air to the interior of the smaller cylinder part d, and for this purpose communi- Cates with or forms an extension of one end of a passage q which at its other end communi- Cates with the smaller cylinder part at a position adjacent to that occupied by one end of the smaller ram part b when the ram is in its initial position as shown, the arrangement being such that the smaller ram part closes the adjacent end of the passage q when the ram commences its operative stroke. In the passage q is also arranged a non-return valve r past which compressed air can flow freely to the cylinder part d. Preferably this non-return valve is made as shown to a hollow cylindrical form With one end closed, and is slidably arranged in an enlargement s of the passage q, so that compressed air can flow freely between the outer periphery of the valve and the inner periphery of the said enlargement. Also the valve r is loaded by a spring t which at one end abuts against the inner side of the closed end of the valve, and at the other end abuts against the adjacent end of the pas- Further, the closed end of the valve r is provided on its outer side with a central enlargement u which co-operates with a seating at the adjacent end of the passage enlargement s to prevent return flow of compressed air from the cylinder part d.

At its delivery end the smaller cylinder part d is provided with an outlet D through which compressed air from the interior of this cylinder part can flow under the control of a valve w` to a delivery pipe or passage :r leading to the machine vdetermined by the regulating valve 3;

to be operated. The valve w is of hollow cylindrical form and is closed at one end, the outer side of this end being provided with a projection 4 adapted to co-operate with and close the outer end of the outlet o under the action of a loading spring y. Also the valve w is slidably arranged in a cylindrical housing a on the cylinder part d, this housing being in communication at its lower end with the delivery pipe or passage cc, and having an outer end provided with an opening v2 leading to atmosphere. The diameters of the adjacent peripheries of the valve w and its hou.,- ing e are made such that a small clearance exists between these peripheries. The loading spring y abuts at one end against the inner side of the closed end of the valve w, and at its other end against the inner side of the .outer end of the housing z. Alternatively the valve w may be loaded by a weight.

when the valve w is in its closed pasaron as Y shown only a small area of its closed end is ex-` posed to the pressure of the air in the cylinder part d. Also the loading of this valve is such that it retains the valve w in the closed position until the pressure of the air in the cylinder part d is increased by the operative stroke of .the ram a, b, to a predetermined extent above that of the air acting on the larger ram part d. Upon the valve Vw .being opened by the air pressure in the cylinder part d, the whole area of the closed end of the valve is exposed to this air pressure, and the Valve is thereby caused to move rapidly into a position in which its open end abuts against the outer end of the housing e and prevents leakage of air through the opening 2. When the air pressure in the cylinder part d is reduced by the return stroke of the ram a, b, the valve w` is returned to its closed position, and the compressed air in the delivery pipe or passage .rcan leak through the clearance between lthe periphery of the valve kand its housing e to atmosphere through the outlet opening 2.

For regulating the pressure at which compressed air is admitted to the intensifier from any convenient source, I may employ any convenient adjustable valve 3.

The compressed air intensier above `described is of simple and compact form and is particularly suitable for obtaining the high air pressures required to inject molten metal, such as aluminium, into the dies of die'casting machines. For this purpose the supply pipe or passage of the intensifier vmay be connected to the compressed air supply main usually provided in a work shop, and the delivery pipe or lpassage is connected to the casting machine.

Startingwith the mechanism with the parts in the relative positions shown in the diagram, the small ,cylinder d is occupied by air at a pressure On opening the valve h air is admitted to the cylinder part c.v By the action of this air on the ram part aithe ram is moved against the action of the spring e. Shortly vafter the ram has begun to move the ram part b closes the adjacent end of the passage q and thereafter compresses 'the air in d; When sumcient pressure is attained in d the valve yw opens the aperture o and closes the aperture 2 and allows the air compressed and displaced by the ram part bto pass along `the passage :c to the die casting machine or other mechanism` to be actuated. During the return action of its spring y. Air can then pass from the die casting or other machine along the passage :c and past the valve w to the outlet aperture 2. When the ram approaches its initial position it uncovers the passage q and the valve r thus allowing the cylinder d to be recharged with air from the passage q.

Referring now to the example shown in Figures 2 and 3, this comprises a slidable ram having a pair of coaxial parts a, b, of different diameters arranged in a corresponding cylinder c, d. Movement of the ram a, b, in one direction is' effected by compressed air acting on the larger part of the ram, and the vreturn is effected by gravity, compressed air or a spring. Air is admitted to and exhausted from the larger or low-pressure part c `of the cylinder under the cont-rol of a pair of poppet type valves h, m, arranged in a chest i,

these valves being operable by a common lever p. The valve h controls communication between a compressed air supply pipe j and `the larger part c 4of the cylinder, whilst the valve m controls communication between the larger part of the cylinder and an outlet 7c to atmosphere. Movement of the lever p in one direction opens the valve h and allows air to passfrom the supply pipe f into the part c of the cylinder. Movement of the lever-p in the opposite direction opens the other valve m and allows air to pass out of the part c of the cylinder to the atmosphere. The smaller or high-pressure part d of the cylinder is provided as in the previous example `with a nonreturn valve 1' past which compressed air from a supply pipe q can flow into that part of the cylinder. l f

The outlet v of the smaller or high-pressure part d of the cylinder has associated with it a pair of valves 5, A6, similar to those above described and associated with the larger part c of the cylinder. These valves 5, 6, are arranged in a chest 1, and are operable by a common lever 8. The valve 5 controls communication between a delivery pipe .fr and an outlet 9 to atmosphere. The valve 6 controls communication between the part d of the cylinder and the delivery pipe x. Movement of the lever 3 in one direction causes the valve 5 to close and the valve 6 Ato open and so allow high-pressure air to be delivered from the part d of the cylinder through the delivery pipe a: to the die-casting or other machine to be actuated. Movement of the lever 8 in the opposite direction causes the valve 6 to .close and the valve V5 to open, allowing air to escape from the machine to atmosphere. The two valve-operat ing levers p, 8 are interconnected, for example by link and lever mechanism I0, so that opening of the valve h for admitting compressed air to the low-pressure part c is accompanied by opening of the delivery valve 6 associated with the high pressure part d of the cylinder, and so thatl the valve m is opened for exhausting air from the low-pressure part c of the cylinder concurrently with the opening of the valve for releasing air from the machine. By interconnecting the operating levers p, 8 of the two pairs of valves I obviate any risk of accidental escape from the intensier, while the latter is not in action, of air admitted by the `pipe q which feeds the vhighpressure part d. The levers p, 8 may be loaded by a spring as I I or a weight tending to hold them in positions in which the exhaust val-ves m, 5, are open and the other valves h, 6, are closed.

For some purposes it is desirable to regulate the rate of flow Vof air from the high-pressure part .d of the intensifier. 'To meet this requirement I provide in association with the delivery pipe x of the high-pressure part d of the cylinder an adjustable valve which comprises a hollow body I2 having an axial bore I3, a bush I4 mounted in one end of the body, and a screw threaded stem I5 having a conical inner end adapted to vary the effective area of a throat IB in the bush, the outer end of the stem being provided with a hand operable hollow actuating head I1 which is suitably graduated to correspond with different rates of ow. Air from the pipe :1: is admitted to an annular chamber I8 surrounding the bush I4 through a lateral opening I9 in a member 20 supporting the bush, and from this chamber air can pass to the throat I6 through radial passages 2| in the bush, the air from the throat passing to the bore I3 of the body l2 for delivery to the machine to be actuated.

For some purposes it is desirable to set a lower limit to the pressure at which air is discharged from the high pressure part d of the intensifier. In other words, it is desirable to ensure that the pressure shall reach a predetermined value before discharge commences after the intensifier has been set in motion. To meet this requirement, I mount an adjustable valve on the high pressure part d oi the intensiiier between the latter and the chest 'I containing the valves 5, 6.

This adjustable valve comprises a hollow cylindrical closure member w mounted in a hollow cylindrical body a. At its closed inner end the closure member w is of conical form and is adapted to co-operate with a complementary seating around anoriiice 29 opening into the high-pressure part d of the intensier cylinder. Behind this oriiice 29 is the outlet v of the intensifier part d and a pipe 22 leading from this outlet to the valve chest l. The closure member 'w is held on its seating by a spring y situated in the interior of the closure member, and the pressure exerted by the spring can be adjusted to any desired amount by a screw 23 in the outer closed end of the valve body a. The screw 23 is adapted to act on the spring y through a thrust piece 24 in the open outer end of the closure member wJ and is provided at its outer end with a hand operable hollow actuating head 25 suitably graduated to indicate the pressures required. Before the closure member w can be lifted off its seating a predetermined pressure must be attained in the high-pressure part d of the intensifier. When this pressure is reached the closure member w opens the orifice 29 and puts the intensifier into communication with the valve chest 1, the closure member being thereafter held oil its seating by the air pressure acting on the full area of the closed end of the closure member. When the air pressure is released the closure member w is returned by its spring y. In the outer end of the valve body a is formed a vent 26, this being acljustable by a screw 21. To prevent air from leaking past` the closure member w to the vent 26 when the closure member is open, the valve body e contains a seating 30 which surrounds the inner end of the vent and against which the outer end of the closure member can abut when in its open position.

For regulating the pressure at which compressed air is admitted to the lowand highpressure parts c, d, of the intensifier adjustable valves 3 may be provided, the pressures being indicated by gauges 28.

The mode of operation of the intensiiier shown in Figures 2 and 3 is similar to that shown in Figure 1. Air is admitted to the high pressure part d from the supply pipe q past the nonreturn valve r. On admitting air from the supply pipe f to the low pressure part c, the air in the high pressure part d is further compressed to the required amount and discharged past the Y' delivery valve 6.

The invention is not limited to the examples above described as subordinate details may be varied to suit requirements. Thus the control valves of the low and high pressure parts of the intensier may take a variety of forms. For example, instead of being of the poppet-type, these valves may have any other suitable form, and if desired a single valve of piston or other convenient type may be used instead of the pair or each pair of poppet-type valves, this single valve beingn adapted to control the pressure air by movement in one direction from a central position and the exhaust by movement in the opposite direction from that position.

Whilst the invention is intended for use more particularly with die-casting machines, it may be used for supplying compressed air to other forms of machines.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A compressed air intensier comprising the combination of a ram having a pair of parts of different diameters, a cylinder in which the ram is arranged and which is provided with two parts of appropriately diierent diameters for accommodating the ram parts, the ram and cylinder being capable of relative sliding movement under the action of compressed air in the direction for compressing air in the cylinder part of smaller diameter, the larger part of the cylinder having a single aperture serving as a common inlet and outlet therefor, valve means for controlling the flow of air to and from the larger part of the cylinder through the single aperture including a casing having a main passageway therethrough communicating with the aperture and provided with a branch to atmosphere, and a pair of valves in the casing respectively controlling the main passageway and the branch, a non-return valve past which air can flow to the smaller part of the cylinder, and valve means fcr controlling communication between the smaller part of the cylinder, the apparatus to be operated, and an outlet therefrom to atmosphere.

2. A compressed air intensier as claimed in claim l, in which the valve means for controlling communication between the smaller part of the cylinder and the apparatus to be controlled is adapted in one extreme position to close a delivery opening in the said cylinder part, and in the other extreme position to close the outlet to atmosphere, the dimensions of the said valve and delivery opening being such that when the latter is closed by the valve only a small part of the area of the valve is exposed to the air pressure in the smaller cylinder part, but when the said delivery opening is open a relatively large area of the said valve is exposed to the said pressure for the purpose described.

3. A compressed air intensifier as claimed in claim l, having in combination with the outlet from the smaller part of the cylinder, a loaded valve made to a cylindrical form, a housing in which the valve is slidably arranged with a clearance between its periphery and the inner surface of the housing, the latter being provided at one end with an outlet opening leading to atmosphere, and at the other end with an opening of considerably smaller diameter than the valve leading to the interior of the smaller cylinder part, and a delivery passage communicating with the housing at a position adjacent to the latter opening, the arrangement being such that in one extreme position of the valve communication between the smaller cylinder part and the delivery passage is interrupted, and the latter communicates with the said outlet opening through the clearance around the valve, whilst in the other extreme position of the valve communication between the smaller cylinder part and the deliverypassage is established, and that between the passage and outlet opening is interrupted.

Il. compressed air intensilierncomprising the combination of a ram having a pair of parts of different diameters, a cylinder in which the ram is arranged and which is provided with two parts of appropriately diierent diameters for accommodating the ram parts, the ram and cylinder being capable of relative sliding movement under the action of compressed air in the direction for compressing air in the cylinder part of-smaller diameter, the larger part of the cylinder having a single aperture serving as a common inlet and outlet therefor, valve means for controlling the flow of air to and from the larger part of the cylinder through the 'single aperture including a casing having a main passageway therethrough communicating with the aperture and provided `with a branch to atmosphere, and a pair of valvesin the casing respectively controlling the main passageway and the branch, a non-return valve past which air can iiow to the smaller part of the cylinder, valve means for controlling comrmunication betweenvther smaller part of -the cylinder, the apparatus to be operated,and anl out` let therefrom to atmosphere, and means connecting the admission and exhaust valve'means asvalve through which air delivered from the v smaller cylinder part can pass.

6. A compressed air intensiiier `as claimed in claim 4 and having in combination with the smaller part of the cylinder, an adjustable valve for determining the minimum pressure at which air can be delivered from the intensier.

7. A compressed air intensifier as claimed in claim 4, in which the Valve means associated with the larger and smaller parts of the cylinder each comprise in combination a pair of poppet type valves, and a lever for actuating both valves, means being provided for interconnecting the two levers so that actuation of the one lever is accompanied by actuation of the other.

GEORGE NORMAN CADBURY.

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