US2501483A - Hydraulic power system - Google Patents

Description

March 21, 1950 N. w. TAYLQR HYDRAULIC POWER SYSTEM Filed Appil 3, 1948 m R 3 0 T M MT N. :WN a v E H a u N Ul- W R .Il U F N T w m f w o up .o 1 7 mw .1 A 3 V W P I-l m \\lNv. m- H M M w Alm 0 .5f ll\\% (u al Z 3 )1 7 EN \..V my A71 4 0 8 4 4 4 4 H m J 3 llll 4 l w l 4 Patented Mar. 21, 1950 UNITED STATES PATENT OFFICE HYDRAULIC POWER SYSTEM Norman W. Taylor, Cleveland Heights, Ohio, as-

signor to The Warner & Swasey Company, Cleveland, Ohio, a corporation of Ohio Application April 3, 1948, Serial No. 18,809

7 Claims. 1

This invention relates to a hydraulic power system valve, and particularly to a valve adapted to be employed in the hydraulic operating circuit to a hydraulic motor which actuates a movable element of an apparatus.v

The apparatus with which the valve embodying the invention can be advantageously employed might be any type of apparatus wherein the hydraulic motor raises and lowers a movable element of the apparatus and which element is subject to different loads or forces at dilerent times and particularly with respect to its lowering movement. As examples of apparatus wherein the valve may be advantageously employed reference is made without limitation to a hydraulic hoist, elevator, the hydraulically actuated pivoted boom of a derrick or of a material handling machine. Inasmuch as the valve may be employed with special utility in the operating circuit of a hydraulic motor that actuates the raising and lowering of a pivoted boom, it will be described herein with particular reference to such an environment. Especially is this the case where the weight of the load raised or lowered by the boom may be different at diierent times and also where the application of the load with respect to the pivotal axis of the boom may change for different operations of the boom.

An object of the invention is to provide an improved and novel valve for use in the operating circuit to a hydraulic motor that actuates the raising and lowering of a movable element of an apparatus and which valve ordinarily provides for a substantially constant predetermined rate of lowering movement or travel of the element at all times irrespective of the load acting on the element during the lowering movement.

Another object is to provide i'n the operating circuit to the hydraulic motor that actuates the raising and lowering of a movable element of an apparatus, a valve which ordinarily maintains during the lowering movement of the element a substantially constant rate of discharge from the exhaust side of the motor, and should back pressure reacting on the exhaust side of the motor develop in the valve in excess of a predetermined pressure, said valve will function automatically and momentarily to reduce from full line pressure the input pressure to the motor until the back pressure falls to or below said predetermined pressure.

Another object is to provide a valve which can be used in the operating circuit to a hydraulic motor that raises and lowers an element of an apparatus and which valve automatically provides for a faster raising operation of the motor and raising movement of the element than the lowering operation and movement thereof and also provides for a substantially constant speed lowering operation of the motor and lowering movement of the element, irrespective of the load applied to the element during its lowering movement.

A further objectv of the invention is to provide in the hydraulic raising and lowering operation of a movable element of an apparatus means for maintaining a substantally uniform lowering rate of movement of the element irrespective of loads, thus providing for safety of operation.

Further and additional objects and advantages not hereinbefore referred to will become apparent during the description of an embodimnt of the invention which is to follow.

Referring to the accompanying drawing;

Fig. 1 illustrates said embodiment of the invention and shows the valve diametrically located in the operating circuit to a hydraulic motor; the section through the valve being taken substantially along line I-l of Fig. 2 and the two plunger valves in the valve being shown in their normal positions.

Fig. la is a sectional view of the valve shown in Fig. l but with the two valve plungers thereof moved automatically from their normal positions and into the positions they may momentarily have during lowering operation of the motor when the back pressure on the exhaust side of the motor exceeds a predetermined pressure and the line pressure on the input side of the motor is momentarily and automatically reduced substantially from full line pressure.

Fig. 2 is a sectional view taken substantially on line 2 2 of Fig. l, and

Fig. 3 is a sectional view taken substantially on line 3-3 of Fig. 2.

The valve embodying the invention is shown arranged in the operating circuit to a hydraulic motor l0 of the reciprocating piston type. The piston I l of the motor slides in the motor cylinder and actuates through a piston rod I2 the raising and lowering of an element I3 of an apparatus. This element I 3 may be in the form of a.

pivoted boom that is raised and lowered at different times under diierent load conditions. During raising operation of the motor l@ to raise the element i3 the piston Il moves upwardly in the motor cylinder, as viewed in the drawing, while during lowering operation of the motor to lower said element said piston moves downwardly in the motor cylinder. The motor cylinder is provided adjacent its opposite ends with ports i4 and l5 to which are connected, respectively, hydraulic lines I6 and l1 that extend to the valve of the invention.

The said valve comprises a valve housing I8 having therein adjacent its lower end, as viewed in the drawing, an L-shaped chamber i9 and adjacent its upper end a chamber 28. The chamber I9 is connected to the line I6 and the chamber 25 is connected to the line l1. .The .valve housing i8 also is provided with a chamber 2l. The chambers i9 and 2l of the valve housing-are'connected by lines 22 and 23, respectively, to any suitable form oi selector valve for selecting 'the direction of operation of the motor.

In Fig. l, and for purposes of illustration only, the line 22 is shown `asconnected .to .a .port 24 .and the line23 to aport 25 `formed in the housing 26 of aselect-or valve and communicating with theinterior .of said housing. The selector valve has rockably mounted `therein a diametrically eX- tending valve vbody '21 which is ,provided with a through ,passage 28 in communication at its midpoint with .a supply .line ,29 extending from a suitable source .of ,supply .of hydraulic -pressure medium. The valve .body 21 may be .rocked by ahandle 13G to .a position wherein the through passage 28 in lthe valve body is in communication with the .port .24 and out of .communication with the port .25 jf-orlowering operation .of the hydraulic motor or to a position wherein said through passage communicates with the port `and .is out of communication .with the portj24 for raising operation of the hydraulic .mot-or. The interior of the valve 'housing .is .connected by a port 3l to an .exhaustfline Sla which functions for Vboth 4of the operative .positonso'f the valve body just referred to. Also the valve body .might be moved to a third or idle position wherein the `passage 2% is .in communication with 'the exhaust port 3l `while'both ports T24 .and 25. are out of communica- `tion with .either the inlet or exhaust sides of the valve.

.The valve'housing L8 adjacent .to the chamber .2li is shown .as -provided `withva through passage closed at its opposite ends by threaded plugs 32 .and .S3 and forminga chamber .34 for a plunger valve .35 that is provided with .three land .portions 38, y3l .and .38., which are slidable in said plunger valve chamber. A spring 39. of prede. termined .strength `is mounted in a central recess of the plug .3.3 and bears against the right hand Y.end of the plunger valve as viewed in Fig. 1

,and acts .to maintain said plunger valve normally in the .position .shown -in Fig. l. The vplunger valve chamber 34 `in 4the normal position of the `v`plunger valve 35 .is in .communication by means of a port 4i! with the chamber 20. The plunger lvalve chamber 34 -also when .the plunger valve is in its normal position is in communication by means of .a .port 4i with .a chamber 42. The chamber 42 is connected also to the left hand end .of the .plunger valve chamber .34, as viewed in the drawing bya small passage 43 which extends to .the left `side of the iland `3.6 of the plunger valve when said valve 'is .in its normal position.

. The chamber 42 is also .connected by a port 44 to the chamber 2l, the effective area of the port 44 being controlled by the tapered end of a needle valve 45 having a threaded stem portion that is adjustably screwed in a threaded opening in the valve housing I8 and which portion projects outwardly of said housing. It will be understood that the needle valve 45, depending upon its particular adjusted position, controls the effective area of the port 44 and provides an adjustable orifice connection between the chambers 42 and 2i. The needle valve 45 may be locked in adjusted position by means .of a threaded cap 46 screwed onto the projecting threaded end of the needle valve.

The valve housing i8 is provided intermediate the chambers i9 and 2l with a circular recess extending into the body from one side thereof and .forming ya chamber 41 for a plunger valve 48 that .is provided with spaced lands 49 and 5U slidable Yin the .chamber 41. The open end of the recess or chamber 41 is closed by a threaded plug 5i which vmounts a spring 52 of predetermined strength corresponding to the strength of spring 39 and which spring 52 bears against the right hand. end of the plunger valve 48 and normally maintains rsaid valve in :the position shown in Fig. l. The recess or ,plunger valve chamber 41 at its left hand end is 'connected by a port 53 to the chamber 42. The ,plunger valve chamber 41 is connected to .the chamber 2l by a port 54 Awhich in the normal position of the plunger valve d3 is closed by the land'5. The plunger or valve chamber 4l is also connected by 'a third port 55 with the chamber i9 and said port 55 is located at .all times ,intermediate the lands 49 and 56.

' The valve housing 18 intermediate the cham- `hers 2li and?! is provided with a'bore 5E closed at its right hand end, vasviewednFigBI by a plug 51 screwed into thevalve housing. The bore 56 adjacent its left hand end, as viewed in Fig. 3, has a valve seat 58, it being noted that the left hand `end of the 'bore' 55 communicates through the valve seat with the chamberf'l. The bore 5E .adjacent the valve seat 58 communicates by a port .'59 with vthe chamber 2), while said bore56 adjacen't its right 'hand end is also in communication with the chamber 2l] by ra Yport 5U. A valve 'Bl is slidable in the `bore 5.6 and is held seated on the seat 5S by a relatively weak spring 62, one end of which -abuts the valve Bl and the other end oi which extends into a `recess formed in the plug 5l.

.The operation of thevalve heretofore described .will now be explained. It will lbe .assumed that 1 hydraulic lpressure is Aon the vthrough passage 218 of the selector valve .body .21 .and that said body is .in the .position shown in ZFig. l and .that the hydraulic motor lll is operating in .the lowering direction. It will .further be `assumed that the needle valve 45 .has been adjusted to the desired adjustment and .that the plunger valves 35 and .4.8 are .in their normal positions as indicated in Fig. l. At this time iull line pressure is flowing from theselector valve 26 .through line .22, chamber l, line l5 and port I4 to the upper side of ythe piston l-i of the hydraulic motor. The hydraulic medium below the :piston il is being yexhausted ythrough port l5. line I1 and into chamber 25. The hydraulic medium in .chamber 2c .acts Athrough port .69 -in conjunction with spring -52 to maintain the valve .6l on its seat 53 and thus to vinterrupt Ycommunication between the chamber 2l and chamber 2D by way .of the bore 56. However, since .the chamber .2D .communicates with the plunger valve chamber 34 the hydraulic Vmedium beneath the piston II will be exhausted through the chamber 20, port 40 and pass between the lands 36 and 3`| of the plunger valve 35 into the chamber 42. The exhausting hydraulic medium will then pass from the chamber 42, through the needle valve controlled port 44 into the chamber 2|. It will be recalled that the needle valve controls the effective area of the port 44, and hence controls the rate of iiow of the hydraulic medium through the port 44. The hydraulic medium exhausted to the chamber 2| then flows through line 23, port 25 to the interior of the selector valve and thence to the discharge line 3|a. If the action of the full line pressure on the upper side of the piston Il, in conjunction with the load of the element I3 acting on the piston, tends to cause the piston to move in a lowering direction at a rate that will cause the hydraulic medium to exhaust into the chamber 42 faster than it can be exhausted therefrom to the chamber 2l through the needle valve controlled port 44, then back pressure will be created in the chamber 42 and such back pressure acting through the passage 43 on the left-hand end Aof the plunger valve 34 will overcome, when it reaches a predetermined pressure, the action of the spring 39 and shift the plunger valve 35 toward the right from the position shown in Fig. 1 to the position shown in Fig. la, wherein the land 36 of the plunger valve 35 closes the ports 4U and 4| and interrupts the exhaust of the hydraulic medium from the chamber '20. This back pressure that may be built up in chamber 42 also acts simultaneously through port 53 to shift plunger valve 48 against the predetermined resstance of the spring 52 from the position shown in Fig. l and into the position shown in Fig. la to move land 50 of said plunger valve to the right of port 54 and thus place the chamber 2| in communication with the chamber I9 through the ports 54 and 55 and the plunger valve chamber 41. Consequently the incoming line pressure is Icy-passed from chamber I9 to chamber 2| and thence to exhaust to reduce the pressure acting on the upper side of the piston I I and thus to decrease the rate of lowering movement of the piston I and the element I3.

Theoretically the hydraulic medium below the piston I I under the conditions just referred to is trapped and the downward movement of the piston would cease. However, this condition is a momentary one, since as soon as the land 36 of the plunger valve 35 has moved to the position shown in Fig. la, the pressure f the hydraulic medium in chamber 42 quickly falls to a point where the spring 39 shifts the plunger valve to its normal position of Fig. 1. Also at this time the spring 52 functions to shift the plunger valve 48 from the position of Fig. la to its normal position Vof Fig. 1. Therefore the chamber 2U after being momentarily closed from communication with the chamber 42 is again in communication therewith while the chamber i9 after being momentarily in communication with the chamber 2| is again out of communication therewith and full line pressure is flowing to the upper side of the piston.

It will be understood that during the lowering operation of the motor the pressure in chamber 42 is maintained substantially constant since the discharge area for the hydraulic medium in said chamber 42 is of a predetermined size by the 'adjustment of the needle valve, thereby allowing the medium to flow from the chamber 42 to the chamber 2| at a substantially uniform rate.

Consequently'the 'lowering movement of the pis'- t'on of the motor I0 is substantially at a uniform predetermined rate, irrespective of the load imposed on the piston duringsuch lowering movement. I

When it is desired to loperate the motor l0 in the raising direction the selector valve body 21 is placed in registry with the port 25, whereupon line pressure flows through the' line 23 and into the chamber 2|. A negligible portion of this pressure will flow from the chamber 2| through the port 44 around the needle valve, through chamber 42, ports 4| and Minto the chamber 2B. However, the hydraulic pressure medium in chamber 2l acting on valve `II will overcome the weak spring 62 and unseat said valve and hence the major portion of the medium` following the line of least resistance will flow from the chamber 2| through the port '59 directly into the chamber 2|! from whence it flows through line Il to the underside yof the piston ll. At this time the cylinder of the motor above the piston is being exhausted through line liychamber I9, line 22, and through the selector valve to discharge. At all times during the raising operation of the motor the plunger valves 35 and 48 remain in their normal positions as shown in Fig. 1. The raising movement being effected at full line pressure is more rapid than the substantially uniform lowering movement of the piston of the hydraulic motor and consequently the element actuated by the motor is raised more rapidly than it is lowered.

The term chamber as used herein to designate the yenclosed spaces I9, 25, 2|, 34, 42 and 41 in the housing I8 is intended to include any enclosed space such as a bore, a compartment, a passage, a cavity or the equivalent. For convenience and to render the claims more readily understandable the chambers I9, 2|), 2| and 42 will be referred to in'the claims, respectively, as through passage, ow chamber, cavity and pressure chamber. Although valves 35 and 4B have been shown and described as plunger valves, it will be understood that various other form of valves subject to the pressure in pressure chambei' 42 might be employed in their place and stead to accomplish the same purposes as do said plunger valves'.

Although a preferred embodiment of the invention has been illustrated and described herein it will be understood that the invention is susceptible of various modifications and adaptations within the scope of the appended claims.

Having thus described my invention I claim:

1. In a hydraulic power system, in combination, a hydraulic motor for' eiecting the raising and lowering of .a movable element of an apparatus and including a cylinder and a piston movable therein, a hydraulic circuit adapted to be connected to a'source of hydraulic pressure and including a direction selector valve and a hydraulic control valve in said circuit intermediate said selector valve and said motor, said control valve comprising a housing having therein a ow chamber and a through passage, said chamber and said passage being connected respectively by said circuit to said motor on opposite sides of the piston thereof, said passage being connected by said circuit to said selector valve, a cavity in said housing and connected by said circuit to said selector valve, a pressure chamber in said housing, means inA said housing providing communication between said pressure chamber and said ow chamber, pressure actuated valve means operatively 7l associated with said last means for controlling communication between lsaid chambers and normally held .in open position by a predetermined force .and subject to the pressure .in saidpres'sure chamber to be moved thereby when said pressure exceeds said force to diminish the communication between said chambers, :means placing said pressure chamber and said cavity .in communication, a valve controllingv the effective area of said communication between said pressure chamber and said cavity, means placing said passage and said cavity communication, and a pressure actuated valve operatively associated with said last means and normally .held in closed position by a predetermined force and subject to the pressure in `said pressure chamber to be moved thereby when `said pressure vexceeds said -forceto establish communication between said passage and said cavi-ty.

v2. A hydraulic power system as dened iii-claim i Iand wherein said housing is provided witha bore closed at its outer end and having its inner end communicating with said cavi-ty., said .bore being provided with a valve seat adjacent its inner end, means located intermediate the inner and outer ends of said bore and placing said bore in 'communication with said vflow chamber, a valve in said bore, and means maintaining said iatter valve against said 'seat with a predetermined press-ure whereby when said cavity is 'subiect to f-ull line pressure 'said valve in said bore is unseated and the incoming hydraulic pressure is icy-passed from said 'cavity through said bore to said -ilow chamber from whence it passes to said motor.

3. In a hydraulic power system, in combination, a hydraulic motor tor effecting the raising and lowering of a movable element of an apparatus and including a cylinder and a piston movable therein, a hydraulic 'circuit connected to said motor and adapted to be connected to a source of supply of hydraulic pressure and includ-ing a direction selector valve and a hydraulic control valve located intermediate said motor and said selector valve, said control valve comprising a housing having therei-nja il'ow chamber connected through said circuit to said motor on one side of the piston while 'said moto-r on the opposite side of the piston is connected through said circuit to said selector valve, a cavity in said housing and connected through sai-d circuit to said selector valve, a plunger valve chamber in said housing, means placing said plunger valve chamber in communication with. said flow chamber, a pressure chamber in said housing, means placing said pressure chamber in communication with said valve chamber intermediate the ends thereof and with said cavity, a valve controlling the eiective area of communication between said pressure chamber and said cavity, a plunger valve mounted in said valve chamber and normally maintained by a predetermined force in a position wherein communication exists between said valve chamber and said now and pressure chambers, and additional means providing communication be tween said pressure chamber and an end of said valve chamber whereby whenever pressure builds up in said pressure chamber exceeding said pre determined force said plunger valve is shifted causing reduction of communication between said flow and pressure chambers.

4. A hydraulic power system as defined in claim 3 and wherein said housing is provided with a bore closed at its outer end and having its inner end communicating with said cavity, sa.id bore being provided with a valve seat adjacent its ine ner end, means located intermediate theinnerand outer ends of said bore and placing said bore ih communication with Isaid Ilcw chamber, a valve Ain said bore, and mean-sv maintaining `said valve against said seat with a predetermined pressure whereby when 'said cavity is subject to full line pressure said valve -in vv'said bore is unseated and the incoming hydraulic `pressure medium is bypassed through said bore from said cavity to said flow 'chamber rom whence it passes to said one side of the .motor piston.

`5f. In ahydraulicpower system, :in combination, a hydraulic motor for effecting Athe raising and lowering fof a movable element vof an appara-tus and :including :a cylinder `and a piston, a hydraulic circuit connected to vsaid motor 'and adapted to be connected to a source of supply of hydraulic pressure and including a direc-tion selector valve and a hydraulic control valve located intermediate said motor and said selector valve, said control valvecomprisin'g a housing having therein a flow 'chamber Vand Ia thorough passage, said flow chamber and said passage being connected respectively to said motor through said circuit on opposite sides of said piston, said passage being connected through said circuit to 'said selector valve, a cavity in said housing and connected through said circuit to said selector valve, a plunger valve chamloer in said housing, means placing said plunger valve chamber in communication with said flow chamber, a second Iplunger valve chamber in said housing, means placing said second plunger valve chamber in communication with said passage and said cavity, a pressure chamber in said housing, means placing said Vpressure chamber in communi'cation with said irst plunger valve chamber intermediate rthe ends thereof and with said second .plunger valve chamber adjacent an end thereof and with said cavity, a valve controlling the 1effective area of communication between said pressure cham-ber and said cavity, plunger valves mounted in 4said plunger valve chambers and normally maintained by a predetermined force in positions wherein communication exists between said iirst plunger valve chamber and said flow and pressure chambers and is interrupted between said second plunger valve chamber and said cavity, and additional means providing communication between said pressure chamber and an end of said iirst plunger valve chamber whereby whenever pressure builds up in said pressure chamber exceeding said predetermined force both of said plunger valves are shifted causing interruption of 'communication between said iiow and pressure chambers and placing said passage and said cavity in communication through said second plunger valve chamber.

6. A hydraulic power system as defined in claim 5 and wherein said housing is provided with a bore closed at its outer end and having its inner endV communicating with said cavity, said bore being provided with a valve seat adjacent its in# ner end, means located intermediate the inner and outer ends of said bore and placing said bore in communication with said iow chamber, a valve in said bore, and means maintaining said latter valve against said seat with a predetermined pressure whereby when said cavity is subject to `full line pressure said valve in said bore is unseated and the incoming hydraulic pressure medium is byepassed through said bore from said cavity to said now chamber from whence it passes to said motor.

'L Ahydraulic power system as dened in claim and wherein said valve that controls the et` iective area of communication between said pressure chamber and said cavity is an adjustable Number valve having provision for manually seating the 1,923,595 same in different adjusted positions to vary the 2,166,940 said eiective area, of communication. 2,272,684

NORMAN W. TAYLOR. 5

REFERENCES CITED Number The following references are of record in the 7751261 le of this patent:

Name Date Temple Aug. 22, 1933 Conradson July 25, 1939 Vickers Feb. 10, 1942 FOREIGN PATENTS Country Date France Oct. 8, 1934

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