US2550723A

US2550723A - Reversing valve mechanism

Info

Publication number: US2550723A
Application number: US712768A
Authority: US
Inventors: Stewart R Ross
Original assignee: FRANK A BEST
Current assignee: FRANK A BEST
Priority date: 1946-11-29
Filing date: 1946-11-29
Publication date: 1951-05-01
Anticipated expiration: 1968-05-01

Description

s. R. oss 2,550,723

REVERSING VALVE MECHANISM May 1, 1951 Filed Nov. 29, 1946 INVENTOR STEWART R. ROSS M 1 EM ATTORNEYS Patented May 1, 1951 REVERSING VALVE MECHANISM Stewart E. Ross, Windsor, Ontario, Canada, as-

signor of one-fourth to Frank A. Best, Windsor,

Ontario, Canada Application November 29, 1946, Serial No. 712,768

; This invention relates to novel and improved reversing valve mechanism for converting rotary motion into reciprocating motion in machines which use a fluid medium for power transmission. An object of the invention is to provide novel and improved mechanism whereby the above indicated end is accomplished automatically, in

large part through, mechanism operatively responsive to' the pressure fluid itself.

A further object of the invention is to provide means of the nature indicated in the last preceding paragraph, and in which a reversing valve is automatically and vintermittently "actuated between two operati g positions, through the medium of a relatively incompressible fluid intermittently acted upon and opposed by a relatively compressible fluid.

A further object of the invention is to provide,

ina system comprising a reciprocating, double acting power piston and a reversing valve, novel and improved means effective upon the reversing valve and responsive alternately to rise of pressure in opposed ends 'of the power cylinder, for actuating the reversing valve so as to periodically reverse the operating pressure in the power cylin A further object of the invention is to provide, in -a double acting power cylinder and reversing valve combination, a liquid impelled by pressure from a pressure source, a power piston reciprocable in' a cylinder, reversing valve means for directing said liquid alternately against opposed faces of said piston, and a pair of chambers,

one respectively in communication with each opposed end of saidpower cylinder, and with either of the opposed faces of said reversing valve,

whereby arise in pressure in eitherv said end of.

:said power cylinder becomes effective upon its respective fluid chamber to compress the fluid in said"'chamber to a critical pressure value, at "which point said reversing valve is caused to reverse, and the liquid pressure is transferred to'the opposite end of said power cylinder.

, A further object of the invention is to provide,

in a system comprising a reciprocating, double acting power piston and a reversing valve, novel and improved means effectiv'e upon the reversing valve to'prevent damage to the system. when unexpected resistance is encountered in the power piston output. I

A further'object of the invention is to provide apparatus. of, the nature generally'indicated in the last preceding paragraph, whereby the power piston is permitted to continueto function in re- 7 Claims. (Cl. 121-150) in a system comprising a reciprocating, double '2 p stricted amplitude of stroke, even when unexpected resistance is encountered.

A further object of the invention is to provide apparatus of the nature indicated in the last two preceding paragraphs,

is encountered, even though the power piston has not completed a full power stroke. A further object of the invention is to provide,

acting power piston and reversing valve, novel and improved means effective upon the reversing valve andresponsive alternately to rise of pressure in opposed ends of the power cylinder, for actuating the reversing valve so as to periodically reverse the operating pressure in the power cylinder, in combination with means for estab- 'J' lishing the maximum pressure to which the first said means is responsive.

Other objects and advantages of my invention will be apparent from a study of the following specification, in conjunction with the accompany ing drawing, in which:

Fig. l is a schematic view, mostly in section, showing in conventional fashion various ele.

merits embodying my invention;

V Fig. 2 is a view similar to Fig. 1, but showing; some of the moving parts in a different-operau ing position;

Fig. 3 is a perspective view, somewhat enlarged, showing the reversing piston-valvj f. Fig. 4 is a sectional view taken (an the line 4 4 of Fig. 3; and v Fig, 5 is a fragmentary sectional view, somewhat enlarged, showing more clearly a corressponding portion of 1.

While the inventive subject matter here. in-

volved is susceptibleo'f application to a varietyoi adaptations, it is here described in connection with the operation of a reversing valve associ-.

ated with a double acting hydraulic powered cylinder and piston unit; I,

Referring to the drawing, and particularly to Figs. 1 and 2 which are schematic in nature, there is shown a power cylinder 10 in which a piston H reciprocates so as to impart appropriate driving motion to a connecting rod [2. The system is of the double acting type wherein the pressure is applied alternately and automatically in chambers l3 and M respectively adjacent the opposed pressure heads 15 and I 5 of the piston. Hydraulic pressure is admitted to chamber l3 through eon duit ll and to chamber l4 through conduit [81 both said conduits having individual communi whereby the reversing valve operates to reverse the direction of travel of the power piston when unexpected resistance cation with a valve cylinder 49 within which a reversing valve 20 is reciprocable. As will later be described in greater detail the hydraulic fluid is impelled by a pump 23, and is thereby advanced through conduit 24 to the reversing valve cylinder I9 whence it proceeds through a selected one of the two conduits I! and It to the chambers I3 and I alternatively so as to produce reciprocation of the power piston and connecting rod Conduit 25 provides an exhaust path from the reversing valvecylinder I9 to the liquid sump 26 whence the fluid may again enter the pump 23 through a pickup conduit 2?. As will now be apparent the hydraulic system is-a. completely enclosed one.

The reversing valve 20 including the means for automatic energization and control thereof, will now be described, reference being occasionally had to Figs. '3 and 4. Valve 26 in the embodiment here disclosed is a cylindrical piston element having an accurate leak-proof sliding fit in the hollow interior of cylinder Hi. In lateral extent the valve is somewhat shorter than its housing chamber so that a limited amount of end clearance is available at either or both ends of the cylinder, the extent of such clearance being of course variable, and continuously changeable by the reciprocation of the valve. For convenience in further reference the end chambers on the left and right in cylinder I9 are designated, respectively, by reference characters so and 3I.

Valve 20' is provided with two distinct pairs of liquid flow passages, one

such pair

32 and 33, consisting of helical grooves, each extending around a, respective semi-cylindrical portion of the valve periphery. "Passage 32, inthe position shown in 2, connects'conduit l? with exhaust conduit 25, and. passage 33 connects conduit I8 with condui't 24 from the pump 23,. The other pair or passages 35and 35, are driiled through the midportion; of valve 28, and are so spaced that in the position shown in Fig. 1, they connect, respective- 1y,- conduit- I! with conduit 24 and conduit I8 with conduit'r25. It will be' apparent that when the valve isin the position shown in Fig. 1, pressure fromthe pump is being applied, in chamber I3, totheleit faceIE of piston I I, chamber I4 beiii-g open to exhaust. In the position shown in Pig; 2', pressure is applied, in chamber I4, to the right face, I6. of piston II, while chamber I3 is open to exhaust. Accordingly reciprocation of valve 28 produces reciprocation of piston II and connecting rod I2.

The general features of a double acting piston, in combination with a reciprocating reversing valve, are known to the art. The present structure has been described in some detail to permit the novel aspects of the invention, now to be described, to be better understood. Such novel aspects reside mainly in the self-actuating means wherebyreversal of valve 2-6 is automatically acconiplishedwvithout mechanical linkage or similar devices. The motion of the reversing valve in the present invention is responsive to pressure conditions existing in the power cylinder chambers I3 and; I4, inoperative conjunction with a compressible fluid in respective chambers in communication therewith.

Temporary maintenance of the valve 28; in the position of'Fig. 1 is assured by a spring biased detent plunger 38, the top of which rests. in a depression 38a in the bottom of valve 253. When forcibly dislodged" from this position the valve may be urged to the right until detent plunger 38 seats in a depression 39a in the position shown in Fig. 2. To maintain proper orientation of the valve, so that the various passages will always move to registration with their respective communicating conduits, shallow grooves 39b extend longitudinally along the outer surface of the valve, adjacent to the

detent seats

38a and 39a, the grooves afiording tracks for the detent plungers during reversal of the piston valve. The detent structure at the right end of Fig. l is more clearly shown in the enlarged fragmentary View, Fig. 5.

Communicating with conduit I1, and with left end chamber 30 of the reversing valve cylinder I9 is an air bell 4B. It'is directly connected to cylinder :19 through pipes 4| and 4m and a pipe 42 provides a. shunt passage between the air bell and conduit IT. A needle valve 43 provides means for controlling the passage of liquid through shunt passage 42.

A similar air bell 44 is connected in like manner through

pipes

45 and 45a with chamber 3I, and through a shunt passage 46 with conduit I8, this shunt passage being likewise under the control of a needle valve 4?. In assembling the apparatus a substantial volume of air, or other compressible gaseous fluid, is trapped in the upper portion 48 of bell 40 and in portion 49 of bell 44.

An operational cycle of the device herein illustrated will now be described. Assume that the various moving parts occupy the position shown in Fig. 1. Chamber I3 is open to hydraulic pressure from pump 23 through conduit 24, valve passage 35, and conduit II. Chamber I4 is open to exhaust through conduit-I8, valve passage 36 and conduit 25. Upon starting of pump 23 the initiation of operation increases pressure in chamber I3,,and piston II moves rod I2 to the right. At the same time pressure begins to build up in bellAO through. piping 4i and 42, thereby compressing. the air in the top 48 of the bell. When piston II reaches the right end of its structure, the pressure in bell 40 builds up to such an extent. as to become effective on valve 20 through the branch 4Ia of pipe 4|. The pressure thus developedmoves reversing valve 20 totheright, namely, to the position shown in Fig. 2. This applies pressure within chamber I4 through conduits I 8 and 2. and valve passage-33. It likewise opens the chamber I3 and the air bell 40 to exhaust. The progress of successive cycles will be obvious from what has already been said.

An. additional advantageous feature. of the invention is that if piston rod I2, or any mechanism with which it is operatively associated, encounters any unusual opposition or obstruction, such as might ordinarily cause damage tosome portion of, such mechanism, andv which stops. the power piston in its travel at any position, pressure will build up in one or other of the bells 4001: 44, so as to actuate valve. 20 and reverse piston II and rod I2. The stroke of the rod will of course be shorter than usual. butv the abnormal operation of the device will no doubt become apparent to an operator so that the obstruction may be removed or the mechanism stopped. In any event such operation is preferableto injury to the machine.

The rate of travel of the main power piston may be varied either by increasing the pump pressure, by increasing the size of the conduits feeding" the power cylinder chambers, or by selectively varying the effective liquid carrying capacity of said conduits. The rate of reversal of the valve 20 maybe varied by varying the needle valve setting, or the air chamber capacity of the bells; Differential fi'ects may be obtained by providing one bell with a greater air capacity than the other. i a 1 What'I claim is: 1. A hydraulic motor including a cylinder having a power chamber, a power piston receptacle insaid cylinder, a conduit adapted to admit a relatively,non-compressible fluid to said power chamber for the movement of said power piston in one direction and alternately, to open said power chamber to exhaust, meansfor moving said power piston'in the opposite direction while said power chamber is open to exhaust, an oppositely movable valve in communication with said conduit andadapted, upon oppositevalve movement, to,control alternate entry and discharge of said non-compressible fluid into and from said power chamber, a fluid chamber in communication with said power chamber, a relatively compressible fluid in said fluid chamber and adapted to oppose the entry thereinto of said non-compressible fluid, whereby the entry of said non-compressible fluid into said fluid chamber produces compression of 'the compressible fluid therein, said fluid chamber also being in direct-communication with said valve, whereby compression 'of the thereof, a power piston reciprocable in said cylinder intermediate said power chambers responsive to admission of relatively incompressible fluid alternately to said power chambers, a pair of conduits, one communicating respectively with each said power chamber, for transmitting said incompressible fluid alternately to said power chambers, a reversing valve cylinder including a double acting reversing piston reciprocable therein, reciprocation of said reversing piston admitting said incompressible fluid alternately to each said power chamber while opening said other power chamber to exhaust, a pair of bell chambers each containing a compressible fluid, communication means from each said bell chamber to a respective power chamberwhereby said incompressible fluid in said power chamber is effective to compress said compressible fluid in said bell chamber, additional fluid pressure communication means from each said bell chamber to a respective end of said reversing valve cylinder whereby pressure built up in said bell chamber'is effective against a respective end of said reversing piston, and whereby reversion of said reversing piston is efiected when pressure in one said bell chamber exceeds a predetermined amount.

3. A hydraulic motor including a double acting cylinder having a power chamber at each end thereof, a power piston reciprocable in said cylinder intermediate said power chambers responsive to admission of relatively incompressible fluid alternately to said power chambers, a pair of conduits, one communicating respectively with each said power chamber, for transmitting said incompressible fluid alternately to said power chambers, a reversing valve cylinder including a double acting reversing piston reciprocable therein, reciprocation of said reversing piston admitting said incompressible fluid alternately to each said power chamber while opening said other power chamber to exhaust, a pair of bell chambers each containing a compressible fluid, communication means from each said bell chamber to a respective power chamber whereby said incompressible fluid in said power chamber is effective to compress said compressible fluid in said bell chamber, additional fluid pressure communication" means from each said bell chamber to a respective end of said reversing valve cylinder whereby pressure built up in said bell chamber is effective against a respective end ofsaid reversing piston, and whereby reversion of said reversing piston is effected when pressure in one said bell chamber exceeds a predetermined amount, and restraining .detent means in operative engagement with said reversing piston and efiective to retain said reversing piston at one or other end of its stroke until pressure in a respective bell chamber exceeds said predetermined amount.

4. A hydraulic motor including a double actin cylinder having a power chamber at each end thereof, a power piston reciprocable in said cylinder intermediate said power chambers responsive to admission of relatively incompressible fluid alternately to said power chambers, a pair of conduits, one communicating respectively with each said power chamber, for transmitting said in compressible fluid, alternately to said power chambers, a reversing valve cylinder including a double acting reversing piston reciprocable therein, reciprocation of said reversing piston admite ting said incompressible fluid alternately to each said power chamber while opening said other power chamber to exhaust, a pair of hell cham bers each containing a compressible fluid, communication means from each said bell chamber to a resepective power chamber whereby saidincompressible fluid in said power chamber is effective to compress said compressible fluid in said bell chamber, additional fluid pressure commu nication means from each said bell chamber to a respective end of said reversing valve cylinder whereby pressure built up in said bell chamber is efiective against a respective end of said reversing piston, and whereby reversion of said reversing piston is effected when pressure in one said bell chamber exceeds a predetermined amount, and adjustable flow control means in said communication means between each said bell chamber and said power chamber for predetermining the rate of pressure increase in each said bell chamber.

5. A hydraulic motor including a double acting cylinder having a power chamber at each end thereof, a power piston reciprocable in said cylinder intermediate said power chambers and responsive to admission of relatively incompressible fluid alternately to said power chambers, a pair of conduits, one communicating respectively with each said power chamber for transmitting said incompressible fluid alternately to said power chambers,.a reversing valve cylinder including a double acting reversing piston valve reciprocable therein, reciprocation of said piston valve admitting said incompressible fluid alternately to each said power chamber while opening the other to exhaust, a pair of bell chambers each containing a compressible fluid, a pair of fluid transmitting pipes, one opening to each said bell chamber, and each such pipe having a first branch opening to a respective conduit, and a second branch opening to a respective end of said reversing valve cylinder, whereby fluid pressure flow from a conduit to either said bell chamber through a first said branch is also effective, through said second branch, against a respective end of said pisassume 7 ten valve; and whereby reversicn ci said-piston valve is effected when pressure ina bell cham ber exceeds a predetermined amount.

6; A hydraulic motor including a double acting cylinder having a power chamber at each end thereof, apower piston rei-pro 1a in said (Lyl inder intermediate-saidpowr c mbers and responsiv'e to admission of relatively i'r'lc'o 'ssibl'e fluid alternately to said power chambers; a pair of'c'ondu'its, one con'a'iiiunicating' respectiveli with each said power chamber for transmitting said incompressible fluid alternately to saidpower chambers, a reversing valve cylinder including a double acting reversin piston valve reciprocabie therein; reciprocation of said piston valve as; ting said incompressible fluid alt'ernatel y to'each saidpowe'r chamber while openingth'e othei to exhaust, a pair of bell chambers, each containing a compressible fluid, a pair of fluid transmittin pipes, one opening to each said bell chamber and each such pipe having a first branch opening to a respective conduit, and a second branch-opening' to a respective end of said reversing valve cylinder, whereb fluid pressure flow from a cond-uit to either said bell chambertlirough a first said branch is also effective, through said second branch, against a respective end of said piston valve, and whereby reversion of said piston valve is efiected when pressure in a bell chamber exceeds a predetermined amount, and adjustable flow control means in said first branch for controlling the rate of pressure rise in said bell chamber.

'7. A hydraulic motor including a double acting cylinder having a power chamber at each end thereof, a power piston reciprocable in said c'ylin' der intermediate said power chambers and re-' sponsive to admission of relatively incompressi'ble fi-uid alternately to said power chambers, a; pair of conduits, one'coinrnunicating respectively with e'acli'said' 'p'ower chamber for transmitting said incompressible fluid alternately to said power chambers, a reversing valve cylinderincluding a double acting reversing piston valve reciprocable therein, reciprocation of said piston valve admitting said incompressible fluid alternately to each said power chamber while opening the other to exhaust, a pair of bell chambers, each containing a compressible fluid, a pair of fluid transmitting pipes, one opening to each said bell chamber, and each such pipe having a first branch opening to a respective conduit, and a second branch openingto a respective end of said reversing valve cylinder, whereby fluid pressure flow from a conduit to either said bell chamber through a first said branch is also effective, through said second branch, against a respective end of said piston va1ve,and whereby reversion of said piston valve is eifected when pressure in a bell chamber exceeds a predetermined amount, and restraining detent means in operative engagement with said piston valve and effective to retain said piston valve at one or other end of its stroke until pressure in an associated bell chamber exceeds a predetermined amount.

STEWART R. ROSS.

REFERENCES cries The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,742,407 McCune Jan. 7,- 1930 l,-920',003- Chenault July 25, 1933 1,938,758 Ernst e- Dec. 12,1933 2,072,403 Lausen Mar. 2-, 1937 Barges 2,302,232 MacNeil Nov. 17, 1942