US2539709A

US2539709A - Air circuit and valve for air saving

Info

Publication number: US2539709A
Application number: US43813A
Authority: US
Inventors: Sykes Thomas Robert
Original assignee: Toronto Star Ltd
Current assignee: Toronto Star Ltd
Priority date: 1948-08-12
Filing date: 1948-08-12
Publication date: 1951-01-30
Anticipated expiration: 1968-01-30

Description

Jan. 3U, 195i T. R. SYKES AIR CIRCUIT AND VALVE: FOR AIR sAvING Filed Aug. 12, 1948 atentec `an. 30,

UNITED STATES Artur OFFICE AIB, CIRCUIT AND VALVE FORAIR SAVING Application August 12, 1948, Serial No'. 43,813y

10 Claims. i.

This invention relates to an air circuit and valve for air cylinders and the object of the invention is to provide improved means for saving air and utilizing it for the return stroke of air cylinders where a powerful operating stroke is required and the return stroke requires much less power, as for instance in air presses, air hammers, etc. In this system air at the end of the power stroke is partially exhausted to the other end of the cylinder and to an air reservoir. This stored air provides power for the return stroke when the remaining air is vexhausted from the power stroke.

According to this invention an air recovery circuit is provided'with a compression tank, a compression line from a source of high pressure to a port on one side of the piston head in the air cylinder, an exhaust line from a port on the other side of the piston head to the said compression tank, an exhaust outlet to atmosphere in the exhaus't line, a by-pass from the compression line to the said tank, an outlet to atmosphere in said by-pass, means for opening the said last mentioned outlet and closing the by-pass between said tank and said outlet when pressure in the high pressure side of the cylinder drops to the predetermined Value, and means to connect the high pressure line through from the source'of high pressure to the compression end of the cylinder and the exhaust line to the outlet to I atmosphere, and alternately to disconnect the high pressure line from the source of high pressure and connect it to the by-Dass and disconnect the exhaust line from the outlet to atmosphere and connect it to the pressure tank, whereby the piston will be actuated initially in one direction by high pressure through the pressure line from the high pressure source and subsequently actuated in the other direction by pressure from the pressure tank.

The invention and the means for carrying it out are hereinafter more particularly described and are illustrated in the accompanying diagrammatic drawing.

Diagrammatically shown is an air cylinder I in which is reciprocally mounted a piston generally indicated as 2 having a piston head 2a and piston rod 2b. In the drawing the piston and other moving parts are shown in full lines in the position they adopt on the return stroke of the piston 2 and in dotted lines in the position they assume on thek power stroke. The air saving valves in the air saving circuit, hereinafter described, are shown in vertical cross section, but the various air lines and other parts of the apparatus including the air cylinder itself are shown diagrammatically on a smaller scale for conveniencelof illustration. The source of high pressure air supply may be any suitable air pump not shown lbut which is referred to in the drawing as high pressure air supply for ready understanding of the invention by reference to the drawing. The air control valve is generally indicated as 3, but it in fact as will be seen from subsequent description comprises three separate poppet valves.

The construction and operation of the device can best be described by rst giving a general outline of the operation of the device, On the power stroke high pressure air from the high pressure air supply passes through air line I to port 5 in valve 3, to port 6 (piston i vbeing in raised dotted line position) to line 8, to port 9 in air cylinder I to provide the downward power stroke of the piston 2. Air is exhausted from below piston 2 through port I0, air line It to and through port I2 in the valve 3, through passage I3 to port I4 in cylinder I5, into cylinder I5 (the piston I6 being in raised dotted line position) and out through exhaust port I1 to atmosphere.

On the return stroke piston l is in lower full line position blockingy compressed airrfrom line Il and piston I6 is also in lower position blocking the passage of air'to exhaust port Il. Cornpressed air from tank I8, however, passes through air line I9 to port 2i] in cylinder 3, port 2l in the cylinder of piston I6 to cylinder I5, out through port Ill (piston I6 being in lower full line position) to and through passage i3 out through port l2 to air line II to and through port I9 beneath piston 2 to raise piston 2 on its return stroke.

The construction and operation of the device will now be described in more detail. The pistons 'l and I6 are controlled pneumatically by a three-way control valve generally indicated as 22 and diagrammatically shown in the drawing. This valve may be operated through stem 23 manually, electrically, hydraulically or pneumatically in a manner which is not shown and does not form part of this invention. Air under pressure is admitted to the valve through air line 24 which is connected to the high pressure air supply line 4 Vand to port 25 in the control valve 22. any suitable three-way Valve may be used the details are not shown. When the valve is in open position port 25 is closed. Port 26 then connects with port 2l to atmosphere. When the Valve is in closed position it connects line 2li through port 25 to port 26 and air line 28. Air line 28 connects with air lines 29 andA 30 which enter valve 3 through ports 3l and 32 respectively beneath Since f poppet pistons 'I and I6 respectively. For the present, cylinder 52 at the end of air line 28 will be ignored since it forms another part of the invention hereinafter described in detail. In open position valve 22 relieves pressure through the

lines

28, 29 and 39 from beneath the poppet pistons 1 and I6. When the valve 22 is closed high pressure air passes to

lines

28, 29 and 30 and through ports 3| and 32 raising pistons 1 and I6. It will be observed that piston 1 in the full line position shown in the drawings has high pressure air from the line 4 pressing on top of its upper disc 1a, but the diameter of the lower end 1b is greater than the diameter of the upper disc 1a so that pressure from below through line 29 and port 3| will raise this valve against the pressure above it. This may be assisted by suitably weighted spring 33 shown in dotted lines within the said lower end 1b and bearing on the bottom of cylinder 34 in which said piston reciprocates.

The pressure aboveupper disc Iiia of piston I6 is, at the lower position indicated,l from the cylinder I5. The pressure in cylinder I5 is approximately one-third to one-half less than the' pressure from the high pressure air supply so that pressure in line 39 has no difliculty in raising piston I6. When the two poppet pistons 1 and I6 have been raised by said air pressure as previously described, they will both be in the power stroke position shown in dotted lines in the drawing. When they have lrst beennraised to this position by the operation of valve 22, poppet piston 35 is still in its lower full line position, with its lower end 35b and upper disc 35? closing the cylinder 38 between ports 31 and 38, being held in that position by compression spring 39 which extends through the wall of valve 3 within casing 48 and bears on the upper disc 35a of the piston 35 and against a disc 4| whose position is adjustable by means of a screw 42 in the upper end of casing 48.

However, raising of piston 'I by pressure through line 29 opens port 43 in the upper end of cylinder 34 permitting the high pressure air as previously described to pass into cylinder 34 and out through port 6 to air line 8 thus starting the piston 2 on its power stroke. At the same time this high pressure air from air line 8 will pass through air line 44 to port 45 in valve 3, into cylinder 36 below piston 35, raising it against the pressure of the spring 39 to the dotted line position, closing exhaust port 46 and opening a pas` sage through the cylinder 36 between ports 31 and 38.

On the other hand, when valve 22 is opened air from lines 28, 29 and 3|] is exhausted through ports 3| and 32, pressure from line 4 entering cylinder 34 will then cause poppet piston 1 to drop, cutting off high pressure supply to the air cylinder I, and pressure from the pressure tank I8 will cause poppet piston I6 to drop opening a passage from the pressure tank I8 to air cylinder I beneath piston head 2a as previously described. However, compressed air accumulated on top of the piston head 2a, will hold up poppet piston 35 through line 44 and port 45. However, in this position the compressed air in the upper part of the air cylinder I will pass back through port 9, air line 8 through port 5a in valve 3 to passage 4l', through port 6 to cylinder 34 and through port 48 to passage 49, port 38, into cylinder 33, up to port 31 (piston 35 still being in upper dotted line position), through passage 50 to port I4, into cylinder I5, up to and through port 2| to port 29, air line I 9 and tank I8 thus providing compressed air for tank I 8. It will also be observed that this compressed air will pass from cylinder I5 through port I4, passage I3, port I2, air line II to port I8 in the lower end of the air cylinder I, the piston 2 at this point being in the lower dotted line position. However, at this stage, air pressure above the piston head 2a is still greater than air pressure below the piston so that there will at rst be no ow of air to the piston below the piston head and hence no movement of the piston.

As pointed out above, at this stage pistons 1 and I5 are in their lower position but piston 35 is still raised. Compressed air from the top of the cylinder I is surging back through line 8 and through cylinder 36 in the by-pass. Pressure in line 44 to port 45 beneath piston 35 is still up. Owing to the distance to be travelled and friction losses there will be some time delay before the pressure in cylinder 36 above piston 35 reaches equilibrium with the pressure through line 44 below piston 35. In other words, during the period of flow through the by-pass the pressure beneath the piston 35 will exceed the pressure above it and the piston 35 will remain in raised position. During this period piston 35 will be supported by pressure through line 44 and port 45. However, at a predetermined time before equilibrium is reached pressure of spring 39 bearing on thetop of piston 35 will causeit to drop, as theother pistons previously have done. The spring 39 is adjusted by means already described so that it will force piston 35 down at a point at which the air pressure above the piston 35 is still slightly less than the pressure below said piston. In other words, at a point where the pressure above the operating piston 2 is still slightly greater than the pressure below the said piston 2 and the tank I8. The spring can, for instance, be adjusted so that the transfer piston 35 will drop at a point at which pressure in the tank I8 has been built up to, say, one-third of the high pressure air supply.

It will be noted that by this arrangement whereby there is flow across the top of transfer valve piston 35 as well as pressure applied beneath it, the point at which valve 35 drops, cutting oir the by-pass, depends on. relative pressures above and below the said piston instead o f upon the absolute pressure in the air line, so that proportionate saving in air is the same regardless of the actual pressure used for operating the airpiston.

When piston 35 falls ydisc 35a closes the Ycylinder3| between ports 31 and 38, thus blocking the flow-back of compressed air from cylinder I5. In other words it :acts as Va check valve. At the same time the dropping of piston 35 opens av passage between port 38 through cylinder 36 to port 48 to atmosphere, so that air flowing back through line 8 from above the piston, will be exhausted through port 46, instead of passing through p-ort 31 to the tank I8, resulting in a rapid drop of pressure above the piston 2, permitting pressure from tank I8, through I9, 28, 2|, I5, I4, I3, I2, |I and I0 to force piston 2 up on the return stroke.

It will be observed that the high pressure line for operating the piston consists of aii` line 4, cylinder 34, passage 41 and air line 3. The exhaust line consists of air line II, passage I3, cylinder I5 and air line I9 to tank I8. In this exhaust line is an exhaust opening I1 to at= mosphere.

It will lalso be observed that passage 49, cylinder 36, and passage e form in eiiect a by-pass between the high pressure line and the exhaust line',` said by-pass containing an opening to atmosphere 46. The valve 35 acts as a combined check valve below a predetermined minimum relative to th'e pressure in the lower part of the cylinder..

A pressure reducing valve is provided in line 5l between the pressure tank and the high pressure line/4 is set at slightly less than normal pressure of the tank i8, and is used to iill up the tank I8 -from the high pressure line 4 to give initial operation on the return stroke and to make up for air leakage during long idle periods, but is not otherwise used.

The poppet pistons l and I5 are standard pistons for controlling air supply to air cylinders'.` Piston 35 is lspecially designed for applicants purpose. I j' A further novel feature is the positioning or clamping cylinder 52 and piston 53. This is used? for positioning the workpiece which isr sub'squently to be tamped by the operation of the pis'- ton 2. When air enters line 28 it will advance piston 53 before poppet valve 'I can be raised against pressure in line 4 to permit compressed air to pass through line 8 to provide the power stroke for piston 2. The proportions of the ends of the piston 'l and the strength of the spring 33 can be adjusted so that a predetermined pressure greater than the pressure required to move pis-` ton 53 is required to raise the piston 1, to provide a delayed action. Return movement of piston 53 is provided through lines Il and 54 in the same manner as the return movement of piston '2.

' What I claim as my invention is:

1. An air cylinder having a piston reciprocal in said cylinder; an inlet and outlet port in the cylinder; a source of high pressure air; a pressure line from the high pressure source to one of the ports to carry high pressure air to the high pressure end of the cylinder; a compression tank; an exhaust line from the other port to said compression tank; an exhaust outlet in said exhaust line; a by-pass from the pressure line to the tank; an outlet to atmosphere in the said loy-vv pass: characterized by the provision of two-way valve means operable to connect the pressure line through from the source of high pressure to the high pressure side of the air cylinder and to simultaneously disconnect the pressure line from the by-pass, and vice versa; two-way valve means operable to connect the exhaust line to the ex haust outlet and to simultaneously disconnect said line from the compression tank, and vice versa; means for simultaneously actuating the said two-way valve means; and transfer valve means in the by-pass, actuated by the relative pressures in the cylinder above and below the piston to open said outlet to atmosphere and simultaneously close the by-pass between said tank and said outlet and alternately to close said outlet and simultaneously open the by-pass whereby the piston will be actuated initially in one direction by pressure through the pressure line from the high pressure source and subsequently actuated in the other direction by pressure from the pressure tank through the exhaust line.

-2. The combination claimed in claim 1 in which the means for simultaneously operating the two-way valve means comprises a valve controlled high pressure air line for operating said valve means in one direction and in which said valve means are operated in the reverse direction by pressure in the pressure line and exhaust line respectively.

3. An air cylinderhaving a piston reciprocal in said cylinder; an inlet and outlet port in the cylinder; a source of high pressure air; "a pressure line from the high pressure source to one of the ports to carry high pressure air to the high pressure end of the cylinder; a compression tank; an exhaust line from the other port to said compression tank; an exhaust outlet in said exhaust line; a by-pass from the pressure line to thetank; an outlet vto atmosphere in the said by-pass: characterized by the provision of a two-way poppet valve operable to connect the pressure line through from the source of high pressure to the high pressure side of the air cylinder and to simultaneously disconnect the pressure line from the by-pass, and vice versa; a two-way poppet valve operable to connect the exhaust line to the exhaust outlet and to simultaneously disconnect said line from the compression tank, and vice versa; means `for simultaneously actuating the said two-Way poppet valves; and transfer valve means in the by-pass actuated by the relative pressures in the cylinder above and below the piston to open said outlet to atmosphere and simultaneously close the by-pass between said tank and said outlet and alternately to close said outlet and simultaneously close the by-pass whereby the piston will be actuated initially in one direction by pressure through the pressure line from the high pressure source and subsequently actuated in the other direction by pressure from the pressure tank through the exhaust line.

4. The combination claimed in claimA 3 in which the poppet valves in the pressure line and exhaust lineare actuated pneumatically.

5. The combination claimed in claim 3 in which the poppet valves in the pressure line and exhaust `line are actuated pneumatically and have upper and lower discs, the lower disc of the poppet valve in the high pressure line being of greater area than the upper disc thereof whereby pressure on the upper disc can be overcome by application of pressure on the lower disc.

6. The combination claimed in claim 3 including a positioning cylinder having a piston, a port at each end of the cylinder on either side of the piston, an air line connected to the source of high pressure and the port on one side of the piston, an air line connected to the exhaust line and the other side of the piston, and an operating valve for operating by a single operation the poppet valve means ingthe high pressure line and exhaust line and the said positioning cylinder.

means operable to connect the pressure line through from the source of high pressure to the high pressure side of the air cylinder and to simultaneously disconnect the pressure line from the by-pass, and vice versa; two-Way valve means operable to connect the exhaust line to the eX- haust outlet and to simultaneously disconnect said line lfrom the compression tank, and Vice Versa; means for simultaneously actuating the said two-way valve means; and a transfer poppet valve in the by-pass', actuated by the relative pressures in the cylinder above and -below the piston to open said outlet to atmosphere and simultaneously close the by-pass between said tank and said outlet and alternately to close said outlet and simultaneously close the by-pass whereby the piston will be actuated initially in one direction by pressure through the pressure line from the high pressure source and sub-- sequently actuated in the other direction by pres sure from the pressure tank through the exhaust line.

' 8. The combination claimed in claim '7 in which the poppet transfer valve is spring pressed to normally open the high pressure side of the by-pass to atmosphere and is operated against said spring pressure by pressure from the high pressure side of the cylinder to close said outlet which a spring is provided on the low pressure side of the control poppet ValveY adjusted to supplement the pressure of the low pressure' line to' actuate the transfer Valve when pressure on the high pressure side of the transfer valve has dropped to a predetermined minimum. relative to the pressure on the low pressure side. l l

THOMAS ROBERT SYKES.

REFERENCES CITD The following references are of record in thev le of this patent:

UNITEDv STATES PATENTSv Number Name Date 1,441,088 Hofstetter Jan. 2, 1923" 2,451,706 Aimes Oct. 19, 19`48