US2984982A

US2984982A - Fluid transmission with control system therefor

Info

Publication number: US2984982A
Application number: US8083A
Authority: US
Inventors: Lawrence F Jaseph
Original assignee: Dover Corp
Current assignee: Dover Corp
Priority date: 1960-02-11
Filing date: 1960-02-11
Publication date: 1961-05-23
Anticipated expiration: 1978-05-23

Description

May 23, 1961 L.. F. JASEPH 2,984,982

FLUID TRANSMISSION WITH CONTROL SYSTEM THEREFOR Filed Feb. ll, 1960 2 Sheets-Sheet l I n ,/soLENolD 195 Hihi' VALVE 159 [65 226 m1111111; soLENolo VALVE 2o Y 9 Y, l sa 69 51 65 57 59 INVENTOR.

LAWRENCE 1'. JAsEPH BY WMM/Z @W May 23, 196 1 F. JASEPH 2,984,982

FLUID TRANSMISSION WITH CONTROL SYSTEM THEREFOR Filed Feb. ll, 1960 2 SheeLs-Shee'tl 2 15 219 223 47 l l1 214 L...} 215 22l Y' f /57 l "www ,83 Il; t 87 201 149 l 1 1 169 4 9 203 FIG. 5

i Y k ,95 l 9 [6l '62 i [97 207 mi 7 l49 22 209 INVENTOR LAWRENCE E JASEPH YBY MM2/,7j

ATTORNEY United States Patent O FLUID TRANSMISSION WITH CONTROL SYSTEM THEREFOR Lawrence F. JaSePh, Memphis, Tenn., assignor to Dover Corporation, Washington, D.C.

Filed Feb. 11, 1960, Ser. No. 8,083 15 Claims. (Cl. 60-52) l This invention relates to improvements in valves, and 1n particular, to improvements in valves to be used in hydraulic elevator systems for controlling the fluid ow during the raising, leveling and stopping of the elevator.

Hydraulic elevators are commonly equipped with a jack cylinder and an elevator car supporting plunger reciprocable therein. For raising the elevator car, hydraulic fluid is supplied under pressure to the jack cylinder by means of a pump. In the elevator system is commonly located valve means for controlling the ilow of the uid during the raising, leveling and stopping of the elevator car. It is towards the improvement of this valve means that the present invention is directed. Heretofore, in its usual form, this valve means comprised a check valve and a by-pass valve, which operated in conjunction with the other parts of the system, generally, as follows: To' raise the elevator, the pump Iwas started and during the initial starting period, the iluid was bypassed to a reservoir until the pump obtained speed. Then the by-pass valve was gradually closed by suitable control means causing the check valve to open and permit fluid to flow to the jack cylinder, whereupon the elevator would rise. Subsequently, when it was desired to reduce the speed of the elevator car as for leveling the elevator car at a desired landing or floor, the by-pass valve was opened to a predetermined size to permit a part of the fluid to be lby-passed to the fluid reservoir While allowing the jack to be actuated by the difference remaining from the pump discharge. This opening of the by-pass valve was usually accomplished by energizing a solenoid valve. In this above-described type of arrangement in which the part of the flow that is by-passed back to the reservoir is regulated, there are many disadvantages, particularly, with the present day high speed elevators and among these disadvantages are the following: Considerable variation in leveling speed occurs when the pump delivery changes, either because of hydraulic slip, motor speed variation, or belt slip as the load on the elevato'r is changed. Also, the stopping distance varies with the load and there is a starting delay.

The present invention overcomes the above-mentioned disadvantages by providing a valve means which regulates the flow that actually passes to the jack cylinder instead of regulating the part of the llow that is by-passed back to the reservoir. In carrying out the present invention, in general, said valve means comprises a novel checkvalve and a novel by-pass valve, which check-valve operates in conjunction with the by-pass valve to permit a desired controlled amount of fluid to ow therethrough to the jack cylinder regardless of elevator load or other heretofore-mentioned variations and the excess of uid or the heretofore-mentioned variations are taken care of by the by-pass valve.

Thus, one of the objects of the present invention is to provide a how-regulating valve which is adapted to perform in a hydraulic elevator system the functions of closing oit the by-pass `luid passage to the reservoir and opening the main fluid passage to the elevator jack to start the Patented May 23, 1961 elevator in an upward direction, subsequently, reducing the volume of the uid ilow through said main passage to a smaller amount for leveling of the elevator car and maintaining this smaller amount constant regardless of variations in the pump delivery, etc., and iinally, closing olf the fluid ow altogether to the elevator jack to hold the elevator car in position.

A further object is to provide such a valve with which a uniform slow-down and stop of the elevator car is obtained regardless of load.

A further object is to provide such a valve having rapid action of the by-pass valve therein.

A further object is to provide such a valve which is adapted to minimize the starting delay of the elevator car.

A further object is to provide such a valve having the advantage over previous valves of this general type of the achievement of the iinal stop by de-energizing a solenoid valve, rather than by energizing one.

A further object is to provide valve means for providing a constant flow of iluid through an out-put conduit thereof regardless of the variations of the input thereto.

A further object is, generally, to improve the design and construction of @ow-regulating valves for elevators.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawings, wherein:

Fig. l is `a sectional View of the valve of the present invention taken as on a vertical plane substantially through the middle of the valve, with portions of the valve being shown in elevation.

Fig. 2 is a diagrammatic view of a hydraulic elevator system showing the principal components thereof, including the valve of the present invention.

Fig. 3 is an enlarged fragmentary sectional view of the compensating valve portion of the device shown in Fig. l, but showing the adjustment screw in section rather than in elevation as in Fig. 1.

Fig. 4 is an enlarged fragmentary sectional View of the relief valve portion of the device shown in Fig. l, but showing the valve in section rather than in elevation as in Fig. 1, and showing the valve in an actuated position.

Fig. 5 is an enlarged fragmentary sectional view of the pilot valve portion of the device shown in Fig. l, but showing the valve in an actuated position and with a portion of the piston being broken away for purposes of illustration.

Fig. 6 is a perspective View of the spring retainer of the by-pass valve portion of the present invention.

Referring now to the drawings in which the various parts are indicated by numerals, the typical hydraulic elevator system shown in Fig. 2, in which the valve 11 of the present invention is adapted to be used, includes the usual jack 13 having a plunger 14 reciprocally mounted in jack cylinder 15, which is adapted to be buried in the ground or otherwise Xedly supported. An elevator car 16 is supported by plunger 14 adjacent the upper end thereof and is provided with the usual guideways, not shown.

Valve 11 includes a valve body 17, which is preferably, though not necessarily, divided in two parts, i.e., a main body 18 and a by-pass body 19 held together along the juncture 20 by suitable fastening means, not shown A conduit or passage 21 leads to valve 11 from pump 23 and is divided at the valve with one branch leading to a check valve 25 located in main body 18, which check valve controls the ow of iluid through an opening 27 in a partition 29 in body 18 separating passage 21 from a conduit or passage 31 leading to jack cylinder 1S; the other branch of passage 21 leads to a by-pass valve 33 located in by-pass body 19, which by-pass valve controls the flow of uid through a port 35 in a partition 37 in body 17 separating passage 21 from a conduit or passage 39 leading to an open uid reservoir 41 containing hydraulic fluid F. Thus, it will be seen from the foregoing that, in general, a main branch from passage 21 to jack 13 is established of which passage 31 is a part, and a by-pass branch from conduit 21 to reservoir 41 is established, of which passage 39 is a part. Also, it will be seen that check-valve 25 controls the flow through this main branch and by-pass valve 33 controls the ow through this by-pass branch. Additionally, the hydraulic system includes a conduit 43 connected between reservoir 41 and pump 23 for supplying fluid to the pump.

yCheck valve 25 includes a throttling member 45 closely and slidably mounted in opening 27. Throttling member 45 includes a substantially circular wall 47 and a plurality of spaced wings 49 integrally formed with circular wall 47 adjacent the outer edge thereof and slidably extending to the right as viewed in Fig. 1 through opening 27 into passage 21 so that the throttling member is guided by wings 49. Wall 47 is beveled as at 51 to lit a corresponding beveled seat 53 in partition 29 adjacent opening 27 so that when throttling member 45 is seated, as shown in Fig. l, there is no fluid escape through opening 27. Throttling member 45 is urged into this closed position by a spring 55, which seats at one end on the left side of wall- 47 and seats at the other end on a cover plate 57 which covers an opening 59 in main body 18 opposite opening 27. A cap 63 is tted over cover plate 57 and secured to body 18 by bolts 65 or the like clampingly to hold the cover plate between the body and the cap. Cap 63 is bored internally to form a smooth cylindrical surface 67 adapted to receive a piston 69 to reciprocate therein. A stem 71 is integrally formed adjacent the central portion of piston 69 and extends axially therefrom through a bore 73 provided centrally through cover plate 57. A bore 75 is provided in stern 71 and telescopically receives a stem 77 integrally formed with circular wall 47 adjacent the central portion thereof and extending to the left therefrom into bore 75. A passageway 79 is provided in stem 77 Which extends from the left end of the stem to an aperture 81 opening into passage 31 adjacent circular wall 47. A passage 83 is provided through cover plate 57 and through body 18 to connect the space S in cylinder 67, which is between piston 69 and cover plate 57 to a conduit or passage 87 further described later. The space 89 in cylinder 67 on the other side of piston 69 from space 35 is in communication with space 135 through a restricted passage 91 in piston 69. Also, space S9 is adapted to be communicated with bore 75 through an opening `93 centrally of piston 69. An adjustment screw 95 is threadedly engaged in a central hole through cap 63 and the body of the screw extends in spaced relationship through opening 93 into bore 75 where the screw is provided with an enlarged head 97 which is larger than opening 93 and which serves as a stop for piston 69 in its travel to the right and also serves to block opening 93 when the piston is moved to the right. A lock nut 99 is provided on the portion of screw 95 which extends on the exterior of cap 63. A spring 101 disposed between cover plate 57 and piston 69 urges the piston towards the left to its at-rest position shown in Fig. 1.

By-pass 33 includes a by-pass valve throttling member 103 closely and slidably mounted in port 35. Throttling member 103 includes a substantially circular wall 105 and an annular side wall 107 integrally formed with circular wall 105 and slidably extending to the right through port 35 towards passage 21. Side wall 107 adjacent its right end is provided with spaced and substantially V-shaped notches 109 so that when the throttling member 103 is in the open position shown in Fig. 1, the fluid ows from passage 21 through the notches into passage 39 and so that when the throttling member is moved to the right by means to be described hereinafter, the notches provide gradually decreasing passage area for the uid until the throttling member reaches its limit in its movement to the right by engagement of the throttling member with a stop 110 provided on body 19, whereupon the port 35 is closed off.

Body 19 is provided with a cylinder 111, which opens into passage 39 on the opposite side of the passage from port 35. Cylinder 111 is preferably of the same diameter as port 35 and is in spaced alignment therewith. A positioning piston member 113 is slidably mounted in cylinder `111. Piston member 113 and throttling member 103 are rigidly interconnected by a connecting member 115 which is integrally formed adjacent its opposite ends respectively with wall 105 and wall 117 of piston member 113. Thus, from the foregoing, it will be understood that a unitary piston assembly 119 is provided, which includes piston member 113 at the left end thereof, connecting member l115 in the middle thereof and throttling valve member 103 at the right end thereof. A bore 121 is provided in piston assembly 119, which extends through connecting member 115 and through wall 105.

A piston 123 is slidably mounted in bore 121 and has integrally formed therewith adjacent the central portion thereof a stem 125 which extends to the left therefrom and slidably through an aperture in wall 117. The end of stem 125- is adapted to receive a snap ring 127 in a suitable groove therein. A port 129 is provided through the wall of connecting member 115 adjacent piston member 113 so that uid is permitted to flow to and from bore 121. A spring retainer 131 is slidably mounted on stem 125 with the stem extending through a hole 132 in the end of the spring retainer and with the spring retainer being prevented from coming off of stem 125 by snap ring 127. 4Spring retainer 131 includes a circular ange 133 which acts as a seat for one end of a spring 135 disposed between the retainer and piston member 113. Additionally, spring retainer 131 includes a hollow cylinder portion 136 integrally formed with flange 133 and projecting to the right therefrom, in the end of which portion the hole 132 is provided. Also, spring retainer 131 includes a substantially disk-like central portion 137 xedly secured to ange 133 and which is adapted to Vcontact a stop screw 139 that threadedly extends through a cap 141 closing the left end of cylinder 111 and fastened onto body y18 as by screws 143. Stop screw 139 is locked in place and secured against leakage by a nut 145 having suitable thread sealing means included therewith. A spring 146 is disposed in piston assembly 119 between wall 117 and piston 123 to urge piston 123 towards the right to an extended position shown in Fig. 1. The force of spring 146 is greater than that of spring 135 so that in its at-rest or normal position piston 123 is in said extended position and spring retainer 131 is held against wall 117, in the position shown in Fig. 1, by snap ring 127.

A group of pilot valves are associated with by-pass Valve 33 and are connected thereto by passage 147 leading from passage 21, passage 149 leading from passage 39, and passage 151 leading from the chamber or space 153 in body 18 behind, i.e., to the left, of piston member 113. This pilot valve group includes an 11p-solenoid valve 155, a compensating valve 157, an up-pilot valve 159, and a relief pilot valve 161.

Valves

157, 159 and 161 are preferably located in a common valve body 162.

Up-solenoid valve closes a port 163 between passage 147 and a passage 165 leading to the up-pilot valve cylinder 167, which port 163 is opened when the solenoid valve is energized and closed when the valve is de-energized.

Relief pilot valve 161 comprises a piston-type valve member 169 slidably mounted in a cylinder 171 provided in valve body 162. Valve member 169 is urged into its normal position, shown in Fig. 1, by means of a spring 173 extending between the right hand end of valve member 169 and an adjusting screw 175 that is threadedly engaged in a threaded aperture in valve body 162. Adjusting screw 175 is secured in place by a screw-cap 177 Valve member 169 is stopped in said normal position by a flange 179 on the right end of the valve member which engages the valve body 162. The left end of valve member 169 is exposed to a passage 181. A bore 183 is provided in valve member 169 and extends from the left end of the valve member to an annular groove 185 in the valve member so that when the valve member is in said normal position, passage 181 is communicated with a passage 187 in valve body 162, as best shown in Fig. 1. Valve member 169 is shiftable against the pressure of spring 173 to the right into the actuated position shown in Fig. 4, under conditions later to be described. Another bore 189 is provided in valve member 169 and extends from an annular groove 191 provided in the valve member through the right end of the valve member so that when the valve member is in said actuated position shown in Fig. 4, the communication between

passages

181 and 187 is closed off, and passage 187 is in communication with an enlarged bore 192 in body 162 and therefore, with passage 149 which is in communication with bore 192.

Up-pilot valve 159 includes a beveled valve head 193 adapted to close off a port 195 between passage 181 and a passage 194 leading to passage 31 when the pilot valve is in a seated position shown in Fig. 1. Up-pilot valve 159 additionally comprises a stem 197 fixed mounted adjacent its left end to valve head 193 and extending rightwardly through port 195 and through an aperture 199 adapted to communicate a passage 201 in body 162 with passage 181 and thence the stem extends through a cylinder 203 in valve body 162, then across passage 149 and into cylinder 167. The end of cylinder 167 is closed off by an access plug 204 threadedly engaged in body 162. At the right end of stem y197 is iixedly and removably mounted a piston 205 slidably mounted in cylinder 167. A small passage 207 is provided through piston 205 to communicate restrictively passage 165 with the portion of cylinder 167 that is on the left side of piston 205 and which cylinder 167 at its left end is, in turn, in communication with passage 149. It will be understood that passage 149 is open to cylinder 167 regardless of the position of relief valve 161.

A spring 209 disposed between piston 205 and body 162 normally urges up-pilot valve 159 to a seated position heretofore described and as shown in Fig. 1 so that communication between passage 181 and passage 194 is normally closed off. Stem 197 is provided with a reduced portion 210 adjacent head 193, which reduced portion is spaced from aperture 199 when the valve is in said seated position so that communication is provided between passage 201 and passage 181. When up-pilot valve 159 is moved to the left under conditions later to be described to the operated position as shown in Fig. 5, valve head 193 unseats from a port 195 to permit communication between passage 194 and passage 181 and at the same time, the enlarged portion of stem 197 enters aperture 199 and blocks oi communication between

passages

201 and 181.

Compensating valve l157 comprises a piston 211 slidably mounted in a bore 213 in body 162, which bore is closed oi'r by an access plug 214 threadedly engaged in body 162. Passage 147 is connected to bore 213 on the right hand side of piston 211 so that the right hand face of the piston is exposed to pump pressure through passage 147 and passage 21. Bore 213 on the left hand side of piston 211 is in communication with passage 149 so that the left hand face of the piston 211 is connected to reservoir 41 through passage 149 and passage 39. A stem 215 is fixed mounted adjacent the central portion of piston 211 and extends to the left therefrom slidably and telescopically into the bore 217 of a hollow adjustment screw 219 which is held in place by a locking lthreaded cap 221. A lateral bore 223 extends through adjustment screw 219 and is adapted to communicate bore 217 with passage 201. The left end of stem 215 has a tapered groove 225 cut in one side of it and adapted to cooperate with adjustment screw 219 to restrict progressively the communication from bore 217 into passage 149 as stem 215 is moved to the left. Thus, the position of stem 215 governs the ow of iluid from passage 201 to passage 149. Passage 201 is in communication with passage 87 which, in turn, is in communication with passage 83, as heretofore described. A solenoid valve 226, whose function will be described hereinafter, governs the ow through passage 87 so that when the solenoid valve is energized the passage is open and when the solenoid valve is de-energized the passage is closed.

The communication between

passages

151 and 187 is provided by a ball-check valve 227 and an adjustable restriction valve 229. It will be understood that when the fluid ows from passage 187 towards passage y151, check valve 227 will be closed and valve 229 will restrict the flow of fluid depending upon the adjustment of the valve, and when the fluid flows from passage 151 towards passage 187, the check valve will open to permit substantially free ow of fluid therethrough.

A detailed explanation of the operation of valve 11 now follows in the order in which events occur when the valve is operated in its usual fashion. To raise elevator car 16, solenoid valve is energized and pump 23 is started by suitable switches and electrical circuits, not shown. This will cause fluid to pass through passage 21 and through port 35 into passage 39 and thence to reservoir 41. The size of notches 109 is such that full pump flow through these notches causes a definite pressure drop, felt as an increase of pressure in passage 21, which is sucient when applied through passages 147 and to piston 205, to deflect it to the left interrupting communication between passages 181 and 281, and establishing communication between passages 181 and .194. Fluid under pressure from jack cylinder 15, therefore, passes through passage 31, passage 194, port 195, passage 181, bore 183, passage 187, restriction valve 229, and passage 151 to chamber 153, where it acts to move piston assembly 119 rapidly to the right as governed by the adjustment of restriction valve 229. This movement carries spring retainer 131 therewith, which spring retainer is at this time abutting wall 117 and holding spring 135 in a compressed disposition. Also, it will be understood that the spring retainer moves away from stop screw 139.

The above mentioned rapidity of movement of piston assembly 119 is due to the substantial excess of jack pressure in jack cylinder 15 and passage 31 over pump pressure in passage 21. As the by-pass valve 33 closes, pressure in pump passage 21 rises and tends to equal that in jack passage 31, which would equalize the pressure difference applied to piston assembly 119 and stop its closing motion. However, this pressure applied to piston 123 is suiicient to overcome the bias of spring 146, and piston 123 moves to the left, carrying with it stem 125 and snap ring 127 which permits spring 135 to expand and carry retainer 131 leftward into contact with stop screw 139, whereupon the spring retainer is held stationary against further leftward movement and spring 13S urges piston assembly 119 to the right which continues the closing action. This action causes the pressure in pump passage 21 to exceed that in jack passage 31, and throttling member 45 of check valve 25 will move to the left to open gradually the check valve and permit flow from passage 21 to passage 31, which opening is resisted only by the relatively light spring 55. The by-pass valve 33 will obtain a fully closed position under the action of spring 135, as above described, and substantially all of the ilow from pump passage 21 will pass to the jack passage 31 through the check valve and so actuate the elevator car 16 at full speed.

As elevator car 16 approaches a landing, suitable mechanical and electrical means energize solenoid valve 226,

V21 conveyed by conduit 147.

At this point it should be noted that during the normal running of the elevator, fluid pressure reaches the space 85 from passage 31 through opening 81, passageway 79, bore 75, opening 93, space 89 and through restricted passage 91. Operation of solenoid valve 226 opens the passage for uid from space 35 through passage 83, passage 87, passage 2111, lateral bore 223, bore 217, tapered groove 225, passage 149, and passage 39 to the reservoir 41. This escape of fluid, which is much greater in volume than can pass through restricted passage 91 causes a substantial pressure diierence across piston 69 and urges it to the right, carrying with it stem 71, which contacts the throttling member 45, and as the area of piston 69 exceeds the effective area of throttling member 45, piston 69 will continue to move carrying with it throttling member 45, thereby restricting the luid iiow through opening 27. This movement to the right of piston 69 and throttling member 45 will continue until piston 69 engages the enlarged head 97 of screw 95, which, in addition to stopping this rightward movement, cuts oi iiuid ilow through opening 93, This action will position throttling member 45 at a given position so as to restrict the passage of uid from pump passage 21 to jack passage 31, causing a rise in pressure in passage 21 which, when applied to the end of piston assembly 119 overcomes the bias of spring 135 and causes piston assembly 119 to move to the left, partially opening the iluid passage through notches 109. When the diierences in pressure, due to the flow through the check valve opening 27 from passage 21 to passage 31 becomes equal in effect to the bias of spring 135, piston assembly 119 will come to rest, and all fluid flow more than required to maintain the specified pressure differential through check valve 25 is by-passed through notches 109. Since this differential pressure depends only on the amount of opening of check valve 25, which is fixed by adjustment screw 95, at a fixed pressure determined by the tension of spring 135, it may be seen that this ow is independent of the actual volume produced by the pump so long as it exceeds the minimum necessary to produce the said pressure difference.

It may be observed that the fluid escaping space 85 during the above-described operation passed through the compensating valve groove 225, and it is to be noted that the position of piston 211 and thus, stem 215 bearing groove 225, depends on the pressure in pump passage If the pump pressure is high, indicating a heavy load being lifted, piston 211 will move further to the left and restrict the exposed area of groove 225 to a smaller passage so that the check valve operating piston 69 will move relatively slowly, while a low pressure in pump passage 21 will move piston 211 relatively little and allow a large passage to be made available for the escape of fluid from space 85, which will not actually permit a more rapid advance, but will otter less restriction to the lower pressure available for motion of piston 69 so at least the same rate may be attained.

When stopping of elevator car 16 is required, as by attainment of a landing, conventional electric circuits, not shown, are interrupted, which causes the de-energizing of

solenoid valves

155 and 226. A suitable timing device, not shown, is employed to continue the operation of the motor, not shown, driving pump 23 for a short interval so that the flow from the pump will continue. When solenoid valve 155 closes, piston 205 moves to the right under the influence of spring 299 with the fluid that is trapped escaping through small passage 207. This carries valve head 193 into a seated position in port 195 interrupting communication between passage 194 and passage 181, while at the same time communication is established through aperture 199. Thus, fluid may escape from space 153 through the following path: Passage 151, ball check valve 227, passage 187, groove 185, bore 183, passage 181, aperture 199, passage 201, lateral bore 223, bore 217, tapered groove 225, passage 149, passage 39, and then to reservoir 41. Since piston 211 is still acted on by the pressure existing in pump passage 21, the abovedescribed escape of fluid will be relatively less restricted as the pump pressure becomes lower, so that the time taken for the by-pass Valve 33 to become suiciently open so that the elevator car 16 no longer moves will be substantially the same whether the 'load on the elevator car is great or small. As the by-pass valve 33 opens wide enough to take the entire flow of pump 23, at the prevailing pressure, check valve 25 becomes completely closed and the passage 31 is cut oi'so that elevator car 16 comes to rest and remains.

lf, when an attempt is made to start elevator car 16 in the 11p-direction, an excessive load is present on the elevator causing a high pressure in passage 31, as soon as piston 205 moves to the left as occurs during the starting of the elevator, as heretofore described, pressure will be admitted from passage 31 through passage 194, port 195, and passage 181 to the left end of piston 169, which will be moved to right against the bias of spring 173 by such excess pressure. Shifting of this piston 169 to the right interrupts the connection from passage 181 to passage 137 and thus to space 153, and instead, establishes a connection yfrom space 153 through passage 151, ball check valve 227, passage l187, 'groove 191, bore 189, bore 192, passage 149, and passage 39 to reservoir 41, so that no pressure can be developed to close the bypass valve 33 any further than it has attained at this time.

From the foregoing, it will be understood that an improved valve is provided which, when reduced speed is desired, controls the ow of fluid to the hydraulic jack cylinder 15 to a constant given amount regardless of the variations of the input to the valve. Further, it will be understood that such a valve is provided which has a unique compensating valve therein that causes pilot passages to be lless restricted when pump pressure is low and more restricted when high so that the actual speed of actuation of the val-ve 11 will be substantially the same at all pressures. In addition, such a valve is provided in which a three-way pilot valve is so connected that the needle valves which control starting and stopping are not both in the hydraulic circuit at one time, and these `adjustments thereby become independent of each other. Also, it will be apparent such a valve is provided having a by-pass valve which is spring biased to the closed position while the pump is running, but which has no bias to close it during idle intervals of the pump, so that the bylpass may remain normally open in preparation for starting of the pump. Additionally, such a valve is provided wherein, when an over-pressure condition exists on the elevator, the by-pass valve is prevented from beginning to close so that the pump operates substantially without load.

Although the invention has been described and illustrated with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited since changes and modifications may be made therein which are within the full intended scope of this invention as hereinafter claimed.

I claim:

l. In `a hydraulic elevator system having a jack cylinder and an elevator car supporting plunger reciprocable therein, a reservoir, pump Vmeans for supplying hydraulic fluid under pressure, conduit means leading from said reservoir to said pump means, a conduit connected to said pump means adjacent one end and branched adjacent the opposite end to establish a by-pass branch and a main branch, said by-pass branch being connected to said reservoir, and said main branch being connected to said jack cylinder, means providing a restricted port in said by-pass branch, a by-pass throttling valve member slidably mounted in said port to provide a normally open by-pass valve, said by-pass valve being operable from said normally open position through two definite phases of closure including a partial closure and a complete closure; positioning means for said by-pass throttling valve member including means establishing a positioning cylinder and a positioning piston slidably mounted in said positioning cylinder, said positioning cylinder being communicated adjacent said one end with said by-pass branch downstream of said port, passageway means communicating said jack cylinder with said positioning cylinder adjacent the opposite end of the cylinder from said by-pass branch, normally closed pilot `Val-ve means in said passageway means for preventing flow through said passageway means, means for operating said pilot valve means towards an open position responsive to the pressure drop of hydraulic iluid through said port whereby fluid under pressure from said jack cylinder is communicated through said passageway means to said positioning piston to rapidly carry said by-pass valve member to said partial closure of said port, said positioning means including means for automatically completing the closure of said port from said partial closure to said complete closure whereby the by-pass of Huid is stopped through said port and the pressure tends to rise in said conduit, and check Valve means in said main branch for operation towards an open position when the pressure tends to rise in said conduit to .permit the tlow of fluid to said jack cylinder and lraise the elevator car supporting plunger.

in a hydraulic elevator system having a jack cylinder and an elevator car supporting plunger reciprocable therein, a reservoir, pump means for supplying hydraulic iluid under pressure, conduit means leading from said reservoir to said pump means, a conduit connected to said -pump means adjacent one end and branched adjacent the opposite end to establish a by-pass branch and a main branch, said by-pass branch being connected to said reservoir and said main branch being connected to said jack cylinder, means providing a restricted port in said by-pass branch, a by-pass throttling valve member slidably mounted in said port to provide a normally open by-pass valve; positioning means for said by-pass throttling valve member including means establishing a positioning cylinder and a positioning piston slidably mounted in said positioning cylinder, said positioning cylinder being communicated adjacent one end with said by-pass branch downstream of said port, passageway means communicating said jack cylinder with said positioning cylinder adjacent the opposite end of the cylinder from said by-pass branch whereby uid under pressure from said jack cylinder is communicated through said passageway means to said positioning piston to urge said by-pass valve member to a partial closure of said port, said positioning means including means for automatically completing the closure of said port from said partial closure to a complete closure whereby the by-pass of fluid is stopped through said port and the pressure tends to rise in said conduit, and check valve means in said main branch for operation towards an open position when the pressure tends to rise in said conduit to permit the flow of fluid to said jack cylinder and raise the elevator car supporting plunger.

3. In a hydraulic elevator system having a jack cylinder and an elevator car supporting plunger reciprocable therein, a reservoir, pump means 'for supplying hydraulic uid under pressure, conduit means leading from said reservoir to said pump means, a conduit connected to said pump means adjacent one end and branched adjacent the opposite end to establish a by-pass branch and a main branch, said by-pass branch being connected to said reservoir and said main branch being connected to said jack cylinder, means providing a restricted port in said bypass branch, a `by-pass throttling valve member slidably mounted in said port to provide a normally open by-pass valve; means establishing a positioning cylinder communicated adjacent one end with said by-pass branch downstream of said port, passageway means communicating said jack cylinder with said positioning cylinder adjacent the opposite end of said positioning cylinder from said bypass branch, a positioning piston slidably mounted in said positioning cylinder, means rigidly interconnecting said positioning piston with said throttling valve member to establish a piston assembly having a rst piston area on the positioning piston end thereof exposed to uid pressure from said jack cylinder through said passageway means and having an opposing piston area on the opposite throttling valve member end thereof exposed to fluid pressure in said conduit, said tirst piston area and said opposing piston area being of such relative areas that when the pressure in said jack cylinder is greater than the fluid pressure in said conduit from said pump said piston assembly is urged towards partial closure of said port, said piston assembly being provided with a bore opening towards said conduit, a iirst piston slidably mounted in said bore, means urging said first piston to a normally extended position for movement towards a retracted position by iluid pressure in said conduit, biasing means seated adjacent one end on said piston assembly adjacent the positioning piston end thereof, holding means connected to said first piston for holding said biasing means in a compressed disposition `against said piston assembly when said lirst piston is in said extended position and for releasing said biasing means when said first piston is moved towards said retracted position by iluid pressure from said conduit, stop means for contacting said holding means when said biasing means is released to establish a stationary base for said biasing means to act against and urge said piston assembly towards complete closure of said port whereby the by-pass of fluid is stopped through said port and the pressure tends to rise in said conduit, and check valve means in said main branch for operation towards an open position when the pressure tends to rise in said conduit to permit the flow of uid to said jack cylinder and raise the elevator car supporting plunger.

4. In a hydraulic elevator system having a jack cylinder and an elevator car supporting plunger reciprocable therein, a reservoir, pump means for supplying hydraulic uid under pressure, conduit means leading from said reservoir to said pump means, a conduit connected to said pump means adjacent one end and branched adjacent the opposite end to establish a by-pass branch and a main branch, said by-pass branch being connected to said reservoir and said main branch being connected to said jack cylinder; check valve means for controlling the flow through said main branch, said check Valve means including means establishing a check valve opening; a check valve throttling member slidably mounted in said check Valve opening and moved to various positions including a fully closed position in which liuid is prevented from flowing through said check valve opening, a fully open position in which the greatest amount of liuid liow is allowed through said check valve opening and an intermediate partially closed position in which the etective opening of said check valve opening is a predetermined size intermediate said fully closed and said fully open positions; check valve positioning means for urging said check valve throttling member from said fully open position to said intermediate position to restrict the fluid flow through said check valve opening, and by-pass valve means in said by-pass branch for maintaining the pressure in said conduit upstream thereof substantially constant when said check valve throttling member is in said intermediate position whereby the restricted fluid ow through said opening is substantially constant regardless of variations in said pump delivery.

5. The structure according to claim 4 in which said bypass valve means includes means providing a restricted port in said by-pass branch, a by-pass throttling valve member slidably mounted in said port to provide a normally open by-pass valve; means establishing a positioning cylinder communicated adjacent one end with said by-pass branch downstream of said port, passageway means communicating said jack cylinder with said positioning cylinder adjacent the opposite end of said positioning cylinder from said by-pass branch, a positioning piston slidably mounted in said positioning cylinder, means rigidlyrinterconnecting said positioning piston with said throttling valve member to establish a piston assembly having a first piston area on the positioning piston end thereof exposed to fluid pressure from said jack cylinder through said passageway means and having an opposing piston area on the opposite throttling valve member end thereof exposed to uid pressure in said conduit, said first piston area `and said opposing piston area being of such relative areas that when the pressure in said jack cylinder is greater than the uid pressure in said conduit from said pump said piston assembly is urged towards partial closure of said port, said piston assembly being provided with a bore opening towards said conduit, a first piston slidably mounted in said bore, means urging said first piston to Ia normally extended position for movement towards a retracted position by uid pressure in said conduit, biasing means seated adjacent one end on said piston assembly adjacent the positioning piston end thereof, holding means connected to said iirst piston for holding said biasing means in a compressed disposition against said piston assembly when said iirst piston is in said extended position and for releasing said biasing means when said rst piston is moved towards said retracted position by iluid pressure from said conduit, stop means for contacting said holding means when said biasing means is released to establish a stationary base for said biasing means to act against and urge said piston assembly towards complete closure of said port whereby the by-pass of fluid is stopped through said port.

6. The structure according to claim 4 in which said check valve positioning means comprises means establishing a cylinder, a check valve positioning piston slidably mounted in said cylinder for movement between a rearward position and a forward position, said positioning piston being provided with an opening therethrough, means establishing a space rearward of said positioning piston, said positioning piston having a back side remote from said check valve throttling member exposed to said rearward space and greater in area than the effective opposing area of said check valve throttling member exposed to uid pressure in said conduit, means establishing a space forward of said positioning piston, said positioning piston having a forward side opposite from said back side and exposed to pressure in said forward space, a rst stern xedly -attached to said positioning piston and extending towards said check valve throttling member, a second stem iixedly attached to said check valve throttling member and telescopically engaged with said iirst stern, biasing means for urging said positioning piston rearwardly toa normal rearwardly at-rest position; means for establishing iluid cornmunication from said main branch downstream of said check valve opening, through said rst and second stems and through said opening in said positioning piston to said rearward space whereby iluid under substantially the same pressure as that in said jack cylinder is present in said rearward space; said positioning piston being provided with a restricted passage therethrough for communicating said rearward space and said forward space whereby the fluid pressure on said forward and back sides of said positioning piston is normally balanced, means for discharging fluid from said forward space faster than fluid can enter through said restricted passage whereby said positioning piston moves against said biasing means towards said forward position carrying with it said first stem into contact with said check valve throttling member and towards a forward position of said iirst stem, an adjustably mounted screw extending in spaced relationship through said opening in said positioning piston, said screw including an enlarged head engaging said positioning piston for stopping the piston and said i'irst stem in said forward positions and for closing off said opening in said positioning piston, said check valve throttling member being held in said intermediate position by said rst stem when said rst stem is in said forward position.

7. The structure according to claim 6 including compensating valve means having a variable opening, said huid discharged from said forward space being discharged through said variable opening, means responsive to iluid pressure in said conduit for Varying said variable opening so that the speed of movement of said check valve throttling member towards said partially open position is substantially constant regardless of variations of delivery from said pump.

8. The structure according to claim 2 including means for interrupting the communication of fluid through said passageway means to said positioning cylinder and for draining the fluid from said positioning cylinder adjacent the opposite end of the cylinder from said by-pass branch whereby said positioning piston is moved to carry said by-pass member towards opening of said port and bypass the fluid flow to said reservoir, compensating Valve means having a variable opening, said fluid drained from said positioning cylinder being discharged through said variable opening, means responsive to fluid pressure in said conduit for varying said variable opening so that the speed of movement of said positioning piston and said by-pass valve throttling member is substantially constant regardless of Variations of delivery from said pump.

9. The structure according to claim 3 including means for interrupting the communication of iiuid through said passageway means to said positioning cylinder and for draining the fluid from said positioning cylinder adjacent the opposite end of the cylinder from said by-pass branch whereby said positioning piston is moved to carry said by-pass member towards opening of said port and bypass the iluid flow to said reservoir, compensating valve means having a variable opening, said iiuid drained from said positioning cylinder being discharged through said variable opening, means responsive to fluid pressure in said conduit for varying said variable opening so that the speed of movement of said positioning piston and said by-pass valve throttling member is substantially constant regardless of variations of delivery from said pump.

10. The structure according to claim l including relief valve means responsive to an excess of pressure in said jack cylinder for automatically interrupting the communication of fluid through said passageway means to said positioning cylinder and for draining the fluid from said positioning cylinder adjacent the opposite end of the cylinder from said by-pass branch whereby said bypass valve is prevented from beginning to close when an excess of pressure exists in said jack cylinder so that said pump means operates substantially without load.

ll. The structure according to claim 3 including relief valve means responsive to `an excess of pressure in said jack cylinder for automatically interrupting the communication of iiuid through said passageway means to said positioning cylinder and for draining the fluid from said positioning cylinder adjacent the opposite end of the cylinder from said by-pass branch whereby said bypass valve is prevented from beginning to close when an excess of pressure exists in said jack cylinder so that said pump means operates substantially without load.

12. In a hydraulic elevator system having a jack cylinder and an elevator car supporting plunger reciprocable therein, a reservoir, pump means for supplying hydraulic fluid under pressure, conduit means leading from said reservoir to said pump means, a conduit connected to said pump means adjacent one end and branched adjacent the opposite end to establish a by-pass branch and a main branch, said by-pass branch being connected to said reservoir and said main branch being connected to said jack cylinder, by-pass valve means for controlling the uid iiow through said by-pass branch, check valve means for controlling the fluid ow through said main branch; positioning means for said by-pass valve means responsive to drain of uid therefrom for causing opening of said by-pass valve means, and responsive to the introduction of fluid thereto from said jack cylinder for causing closure of said by-pass Valve means; passageway means for introducing uid to said by-pass valve means from said jack cylinder, needle valve means in said passageway means for controlling the ow of fluid therethrough; positioning means for said check valve means responsive to drain of fluid therefrom for causing partial closure of said check-Valve means to a predetermined degree, compensating valve means having a variable opening for `Viiuid to flow therethrough, means responsive to pressure changes in said conduit for varying said variable opening in accordance with the pressure in said conduit so that the fluid ow therethrough is substantially constant regardless of variations in delivery from said pump means, and pilot valve means for selectively directing through said compensating means the uid discharged from said cheek valve means and said by-pass valve means so that the partial closure of said check valve means and the opening of said by-pass valve means is substantially constant regardless of variations in delivery from said pump means.

13. In a hydraulic elevator system having a jack cylinder and an elevator car supporting plunger reciprocable therein, a reservoir pump means for supplying hydraulic liuid under pressure, conduit means leading from said reservoir to said pump means, means establishing a passage for communicating fluid from said pump means to said jack cylinder, check valve means operable to a partially closed position for reducing the uid ow to said jack cylinder, positioning means operably coupled to said check valve means for moving said check valve means from an open position to a partially closed position determining an opening of a predetermined xed size and said positioning means holding said check valve means at said partially closed position, and uid by-pass means communicated with said conduit for holding the pressure in said conduit substantially constant at any given effective size of opening of said check valve means whereby the amount of fluid ow through said check valve means to said jack cylinder remains substantially constant regardless of variations in delivery of said pump means.

14. Means for controlling the iiow of uid through a passage comprising means establishing a restricted port in said passage, a throttling valve member slidably mounted in said port to provide a normally open valve; means establishing a cylinder communicated adjacent one end with said passage downstream of said port, a source of high pressure uid higher in pressure than the iiuid in said passage upstream of said port, passageway means communicating said source of high pressure uid with said cylinder adjacent the opposite end of said cylinder from said passage, a positioning piston slidably mounted in said cylinder, means rigidly interconnecting said positioning piston with said throttling valve member to establish a piston assembly having a irst piston area on the positioning piston end thereof exposed to liuid pressure from said source of high pressure fluid through said passageway means and having an opposing piston area on the opposite throttling valve member end thereof exposed to fluid pressure in said passage, said first piston area and said opposing piston area being substantially the same effective areas whereby said piston assembly is urged towards partial closure of said port by said high pressure uid, said piston assembly being provided with a bore opening towards said passage, a irst piston slidably mounted in said bore, means urging said rst piston to a normally extended position for movement towards a retracted position by fluid pressure in said passage, biasing means seated adjacent one end on said piston assembly adjacent the positioning piston end thereof, holding means connected to said first piston for holding said biasing means in a compressed disposition when said iirst piston is in said extended position and for releasing said biasing means when said first piston is moved towards said retracted position by iluid pressure from said passage, stop means for contacting said holding means when said biasing means is released to establish a stationary base for said biasing means to act against and urge said piston assembly towards complete closure of said port whereby the iiow of uid is stopped through said port.

l5. Means for controlling the ow of fluid through a passage comprising means establishing a restricted port in said passage, a piston assembly including a throttling valve slidably mounted in said port to provide a normally open valve, positioning means for moving said throttling valve to partially close said port, said piston assembly being provided with a bore opening towards said passage, a first piston slidably mounted in said bore, means urging said first piston to a normally extended position for movement towards a retracted position by liuid pressure in said passage, biasing means seated adjacent one end on said piston assembly adjacent the positioning piston end thereof, holding means connected to said rst piston for holding said biasing means in a compressed disposition when said first piston is in said extended position and for releasing said biasing means when said iirst piston is moved towards said retracted position by fluid pressure from said passage, stop means for contacting said holding means when said biasing means is released to establish a stationary base for said biasing means to act against and urge said piston assembly towards complete closure of said port whereby the flow of iiuid is stopped through said port.

References Cited in the tile of this patent UNITED STATES PATENTS 2,280,291 Jaseph Apr. 21, 1942 2,782,599 Stelzer Feb. 26, 1957 2,797,550 Stelzer July 2, 1957