US1919402A

US1919402A - Steam driven fluid compressor

Info

Publication number: US1919402A
Application number: US454555A
Authority: US
Inventors: Benjamin H Thompson
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1930-05-22
Filing date: 1930-05-22
Publication date: 1933-07-25
Anticipated expiration: 1950-07-25

Description

Jul 25, 1933. r B. H.-THOMPSON STEAM DRIVEN FLU'ID COMPRESSOR F iled May 22, 1930 6 7 53 3 42 1 m 52 o 52 m 5 9 MM 4. I0 in mm 5 8 .T A 4 2o I s 4 W 5 7 6 l 5 2 O O 4 3 5 I 5 a INVENTC DR BENJAMlN H.THOMPEON %KK%W ATTO NEY .IQ: 4

Patented July 25, 1933 entree STATS EGUSE AIR BRAKE COMPANY, OF WILIK 7 GE PENNSYLVANIA ATENT me BENJAMIN THOMPSON; or ARDARA,'PENNSYLVANIA, AssIeNon T mnnwns'rrnor- ERDING, PENNSYLVANIA, A oonronarron STEAM nnrvnn rte-"in oolyrrninsson- Application filed May 22,

Thisinvention relates to steam actuator fluid pressure compressors and more particularly to the direct acting type in winch the engine pistons aredirectly connected'to the air compressing pistons.

controlling the reversing movement of said pistons.

The principal object of my invention 1s to provide an improved valve mechanism for controlling the operation of the engine pistons or a Fluid pressure compressor of the above type. and more particularly to an improved valve mechanism having no mecha 11- cal connection to the operating parts of the engine or compressor.

Other objects and advantages will appear in the following more detailed description of mi." invention.

in the accompany 3 drawing; Figure l is a central, vertical diagrainnia i section of a compound steam actuated fluid pressure compressor enibodying my inisintion; Fig. 2 a hugnnnnrrlic view oi the control valve port on oi the compressor shown in Fig. 1 but with the operating part shown in the opposite position; Fig. 3 is a sectional View of an anxilia Y valve employed in the control valve portion of the con'ipressor; and t an end elevation of said auxiliary valve.

As shown in the drawing, the compressor. coniprises arasing formed of a motor por-v tion 1, an air compressor portion 2, an intermediate section 3 interposed between the

pertions

3 and 2. a lower cover portion i, and a top cover portion B said portions'heing together in the relation shown in the drawing. i

A high pressure steam piston 6 is contained in a cylii'ider T of the portion 1 and is connected by a rod 8 with a low pressure air piston 9 contained in a cylinder 10 of the portion 2, while a low pressure steam piston 11 is contained in a cylinder 12 of the portion 1 and is connected by a rod 13to a high pressure 1930; Serial no; 454,555

air piston 14: contained in a cylinder 15in the portion 2. The air compressing portion of the compressor is of the usual well known type having inlet valves 16 to thelovv pressure air cylinder 10, combined exhaust and inlet valves 17 from the'low pressure air cylinder 10 to the high pressure air cylinder'1'5 and exhaust valves 18 from the high pressure air cylinder A control valve por'tion i's' provided in the top cover'5 for governing the supply and exhaust of steam to and from thefst'e'a in cyl inders and for controlling the reversing of the motor pistons 6 and 11- andcomprises a series of connected

piston heads

19,20, 21 22 of the same area, a piston head 23 ot'agreater area and a piston head :24 having an "preferably disposed in; a single bushing 64 mounted in the casing 34, but since the'piston area intermediate the areas of pistons 22 and 23 isof larger diameter'than piston 24:, the

piston 24-isdisp0sed in another bushing" 32 having an outside diameter larger than that of the piston 23. The bushing 32 is carried by a cover plate 33 and has an extension adapted to slide into a suitable recess in the control valve casing 34. lVith the cover 33 and the bushing 32 removed from the casing 34, the series of connected

pistons

19, 20; 21, 22, 23 and 24 are adapted to be assembled, in the bushing 640f casing 34, as a unit, through the right hand end of said casing. WVith said pistons thusassembled, the cover 33 with the bushing 32 is'mounted in place as shown in the drawing. Projecting from the outer face ofpiston 19 is a boss 25, andprojecting from said boss is a'stem 26 of smaller diameter, said stem26 being 'providedat its outer end' with a button 'shaped head 27. The stem 26 is adapted to at one time and by engagementwith-the boss '25 at" another time, the distance between said button and boss being greater than the thickness of the end of the valve 28so as to provide lost motion between the valve 28 and the control pistons.

The valve 28 is mounted in a bushing 29 in a cover 35 adapted to be secured to the casing 34, said bushing being adapted to slide into a suitable recess formed in the casing, in the drawing.

Adjacent the bore 30 in the valve 28 is a diagonal bore 31 of a diameter slightly larger than the diameter of the button 27 on the stem 26. lVith the control pistons in the position shown in Fig. 2, and with the. cover 35 removed from the casing, the valve 28, which may be assembled in said cover, is connected to the stem 26 by sliding the bore 31in the "alve 28 over the button 27. When said button is thus placed within the valve, the cover 35 and said valve are. centralized with the control pistons, so that stem 26 enters the bore 30 in the valve,after which the cover is socured to the casing and operating engagement as shown between the controlpistons and the valve 28 is thereby attained.

I In operation, with the control valvepistons in thegposition shown in Fig. 1 of the drawing-steam supplied to pipe 36 flows through passage 37 to chamber 38 between the pistons 21 and 22 and from thence through passage 39 to chamber 40 at the left hand side of piston 19 and from said chamber through passage 41,to the chamber above the high pressure piston 6, thus causingsaid piston to move downwardly,as indicated by the arrow on therod 8. i y f j V Vhenthe high pressure piston 6 nears the end of its downward stroke, a groove 42 in the cylinderwall, which connects with a passage 43, is uncovered by said piston and permits high pressure steam to flowfrom the upper side of said piston through passage 43 to chamber 44 at the outer face of the control piston-24. The piston 24 being of greater area than piston 19, which at all times is subjectto highsteam pressure, the unbalanced steam pressure acting on piston 24' shifts the

control pistons

19, 20, 21,22, 23 and 24 toward their left hand position, as'shown in Fig. 2

of the drawing.

Due to. thelostmotion betweenthe control pistons and the valve 28, the initial movement of the control pistons isindependent of said valve and when boss 25 ust engages said valve, the passage 41 is lapped by the control piston 19 thereby cutting off the steam supsure steam is permitted to flow from the upper side of the high pressure piston 6 to chamber 45 and therein act on the pistons 23 and 24. The piston 23 being of greater area than piston 24, the unbalanced steam pressure 1s thus increased just as the boss 25 engages the valve 28 and is adapted to oflset the resistance to movement of the valve 28 so as to ensure positive and full reverse movement of the control pistons and valve 28 to the extreme .20 and passage 41, so that steam at intermediate pressure is permitted to flow from the upper side of the high pressure piston 6 to the upper side of the low pressure piston 11 and cause the piston 11 to move downwardly. At the same time, high pressure steam flows to the chamber-at the lower side of the high pressure steam piston G-by way of pipe 36,

passage37, chamber 38 intermediate the con: trol pistons 21 and 22, and passage 47, and causes the high pressure steam piston G to move toward its upper position.

The movement of the valve 28 to the left hand position as effected by the control pistons, causes an annular passage 54 to connect a passage from the groove 53 in the upper end of the high pressure steam cylinder to passage 55 which connects to chamber 56 between the control pistons 22 and 23, so that steam at intermediate pressure from the upper side of the high pressure steam piston 6 is permitted to be effective in the control piston-chamber 56. As hereinbefore described, high pressure steam from the upper side of the high pressure steam piston is supplied through passage 46 to control piston chamber 45 to ensure movement of the control pistons to the left hand position, but upon reversal of theengine pistons, the pressure in chamber 45 becomes intermediate pressure such as acts to operate the low pressure steam piston. Thus, upon full movement of the control pistons and the valve 28 to the left h and position, the control pistons are maintained in said position by an unbalanced steam pressure equal to the difference between the high and intermediate steam pressure times the difference in area of the piston 19 and the piston 24.

With the valve 28 in its left hand position as shown in Fig. 2, when the high pressure steam piston 6 uncovers the groove 53 in the cylinder wall as the piston approaches the end of its upward stroke, high pressure steam is permitted to flow through passage 65, annular passage 54 around the valve 28 and passage 55 to control piston chamber 56 and act on the pistons 22 and 23. The piston 23 having a relatively large area, the high steam pressure acting thereon unbalances the control pistons and causes them to move to their right hand positions, as shown in'Fig. 1 of the drawing. V

In the right hand position of the control pistons, the chamber at the upper side of the low pressiu'e steam piston is connected to the exhaust passage 48 through passage 51 and control piston chamber 52, and steamat in- 19 tcrmediate pressure is permitted to flow from the lower side of the high pressure steam piston through passage 47, control piston cham her 49 and passage 50 to the lower side of the lowpressnre steam piston and move said pis- 5 ton upwardly. At the same time, steam at high pressure flows from the supply pipe 36 through passage 37, control piston chamber 38, passage 39, chamber 40 at the outer side of the control piston 19 and passage 413:0 the of the high pressure steam piston 6 to chainward stroke and uncovers groove l2, steam ber 56 intermediate the controlpistons Q2 and 23 by way of passage 47, chamber l9,

intermediate the

pistons

26 and 21, passage annular passage and passage *As hereinbefore described, high pressure steam is supplied to the control piston chamber 56 to ct t reverse movement of the control pistons to the right hand position but by moving the valve 28. steam at intermediate pressure is supplied to piston chamber 56 and the con- .trol pistons are maintained in their right hand position by the high steam pressure acting on the piston 19, When the high pres sure steam piston G nears the end of its downt high pressure is supplied to'chamher 4L4 istons to their left hand positiomas hereinbefore described in oetail. i

From the above description of the operation of my improved control valve mechanism tor a steam actuated motor, it will he noted that the piston 23 is the reversing ele ment, the piston 24 being employed to start the reverse movement from the right hand position to the left hand position. Essentially.;however, piston 24 is employedto permit obtaining of an unbalanced steam prcs-' :4} sure condition for shifting the control valve,

Ziicchanism from the left hand position to the right hand position, which would be impossihle if high pressure steam were permitted to be effective in the control valve piston chamber 4-5 through passage 4:3 when the high the outer'tace of the control piston 2i and. said piston then operates to shift thecontrol pressure steam piston (Sis moving upwardly.

It will further be noted that the valve 28 is employed for controllin the pressure in the control piston chamber 56 in accordance with the direction 01" movement of the high pressure steam piston (3 and is operative, at one time to permit intermediate steam pressure to be supplied to said chamber to permit reverse movement to the left hand position and at another time to permit high pressure steam to be supplied to said chamber to cause reverse movement to the right hand position.

- Lost motion between the control pistons and the valve 28 is provided so as to ensure a substantially complete reverse movement of the control pistons before said valve is moved so as to ensure full reversing and prevent pos sihlestalling of the motor. With. this construction, there is no dead center upon which the control valve mechanism can. stop which would. prevent it from starting.

One particular adv ntage of my improved control valve mechanism is the absence of any mechanical connection between the moving par-ts of the air compressor'or air compressor motor and the moving parts of the control valve on thetop cover portion.

The passage e'l-Bconnects to a recess 60 in the bushing 32 containing the control piston 24 in the right hand position shown in Fig. Due to thisconstriultion a cushion is ro- 1" F vided to resiliently stop the movement oi' the control pistons in moving to the right. A

cushion is also provided to resiliently stop the control pistons in their movement to the left. It will be noted that the cover 35 containing the valve. 28 is provided with boss 61 slidably extending into a bore in said valve and said boss. is provided with a slot 62, which in the position of the valve m chanism shown in 1 is partly uncoveredby the open end of said valve. When said valve is being moved from the righthand position tothe left hand position, steam is permitted to escape from the chamber 63 at the left hand side of said and the piston. 24 laps the recess-60 when llL openings 42 and 53, respectively, in thehigh' pressure steam cylinder. These elongated openings are. adapted to time the reversing movement of the control valve, in respect to theposition of the highpressure steam piston 6 in its cylinder, in'the manner hereinbetore described, and may bevaried in length to change saidtiming if desired. For illustration, I have shown my invention associated with a steam actuated motor employed for operating a fluid pressure Y tioned limit its scope, since it can be equally well employed with any motor employing an expansible' gas as an operating medium.

lVhile one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what Iclaim as new and desire to secure by Letters Patent, is:

1. A fluid pressure actuated motor comprising a cylinder, a motor piston mounted in said cylinder, a reversing valve comprising a plurality of connected abutmcnts for con trolling the supply and exhaust of fluid under pressure to and from said cylinder for operating said motor piston, a pair of connected pistons of dii'tercnt areas for moving said abutments, a passage for connecting one side of one of said diiterential area pistons to one side of said motor piston for initiating the reverse movement of said valve, another passage adapted to connect the adjacent sides. of said differential area pistons to said one side of said motor piston for completing the reverse movement of said valve, and a valve loosely connected to and operated by said difl'erential area pistons for controlling comi'nunication from said cylinder to the oppo-- site side of the other of said differential area pistons.

2. A fluid pressure actuated motor comprising a cylinder having a port adjacent each end, a piston disposed in said cylinder and movable over the port at each end of said cylinder, valve means having a reverse position for controlling the supply and eX- haust o1 fluid under pressure to and from the opposite sides oi? said piston, a movable abutment connected to said valve means and operat ve by fluid under pressure supplied through one of said ports to move said valve means to reverse position, another movable abutment connected to the first mentioned movable abutment, a passage adapted to be uncovered by movement oil the second men abutment for supplying fluid under pressure to one side of the second mentioned abutment for increasing the force moving said valve means to reverse position, and means operative upon movement of said valve means to reverse position to supply fluid under pressure from the other of said ports to the other side of the sccond mentioned abutment for returning said valve means to their initial position.

A fluid pressure actuated motor comprising a cylinder having a port adjacent each end, a piston disposed in said cylinder and movable over the port at each end of said cylinder, valve means having a reverse position for controlling the supply and exhaust of fluid under pressure to and from the opposite sides of said piston, a pair of movable abutments of different diameters connected to said valve means and movable by fluid under pressure supplied through one of said ports to the outer side of one of saidabutments to initiate the reverse movement of said valve means and to open a passage from one side of said piston for supplying fluid under pressure to the adjacent sides of said abutments for increasing the movingforce .on said valve means, and means operativeupon movement of said valve means toreverse position to supply fluid under pressure from the other of said ports to the outer side of the second mentioned. abutment for returning said valve means to their. initial position.

4. A fluid pressure actuated mot-oncomprising a cylinder having a port adjacent each end, a double acting motor piston movably disposed in said cylinder, and means for controlling the operation of said piston, said means comprising a valve device for controlling the supply and exhaustof fluid under pressure to and from the opposite sides of said piston, a reversing piston having a chamber at one side in constant communication with one of said ports and adapted to move said valve device in one direction, auother reversing piston having a chamber at one side adapted to be connected to the other of said ports for moving said valve device in the reverse direction, and a valve movable by said valve device for'controlling communication to the chamber of the second mentioned reversing piston.

5. A. fluid pressure actuated motor comprising a cylinder having a port adjacent each end, a double acting motor piston movably disposed in said cylinder, and means for controlling the operation of said piston, said means comprising a valve device for controlling the supply and exhaust of fluid under pressure to and from the opposite sides of said piston, a reversing piston having a chamber at one side in constant communication with one of said ports and adapted to move said valve device in one direction, another reversing piston connected to the first mentioned reversing piston for moving said valve device in the reverse direction and having a chamber at one side, a valve controlled by said reversing pistons and adapted to connect the last mentioned chamber to the other of said ports, and means for connecting a chamber intermediate said reversing pistons to one side of said motor piston upon a predetermined movement of said valve device by the first mentioned reversing piston.

6 A fluid pressure actuated motor comprising a cylinder having a port adjacent each end, a. double acting motor piston mov- "abiy disposed in said cylinder, and means for controlling the operation of said piston, said means comprising a valve device for controlling the supply and exhaust of fluid under her at one side adapted to be connected to the other of said ports for moving said valve i0 device in the reverse direction and means comprising a valveloosely connected to said valve device and movable thereby for opening communication-from the last mentioned chamber to the other of said ports upon a predetermined movement'of said valve device by the first mentioned reversing piston.

BENJAMIN H. THOMPSON.