US3125120A

US3125120A - hasbany

Info

Publication number: US3125120A
Authority: US
Publication date: 1964-03-17
Anticipated expiration: 1981-03-17

Description

March 17, 1964 w. A. HAsBANY 3,125,120

CONTROL VALVE Filed Feb. v6, 1961 2 Sheets-Sheet l IEE WW |'V 'l'.

March 17, 1964 w. A. HAsBANY 3,125,120

CONTROL VALVE Filed Feb. 6. 1961 2 Sheets-Sheet 2 304 -aao soo 298 284 289 262 l INVENTR. u

30+ y2go l woooRow A. HAssgNY `ATTORNEY United States Patent O M 3,125,120 COOL VALVE Woodrow A. Hasbany, South Bend, 1nd., asslgnor to Clark Equipment Company, a corporation of Michigan Filed Feb. 6, 1961, Ser. No. 87,214 7 Claims. (Cl. 137596.12)

The present invention relates to valves and more particularly to directional control valves for either single or double acting hydraulic cylinders.

Conventional directional control valves for hydraulic cylinders, either of the single or double acting units, frequently permit the load on the hydraulic unit to drop or otherwise yield unavoidably of its own weight as the valve is operated. In single acting cylinders this is the result of communication through the valve between the source of pressure and the pressure side of the cylinder before suicient pressure in the valve has been reached to equal or exceed the counter force applied by the load on the unit. Various types of check or poppet valves have been employed in directional control valves between the control element and the cylinder, to prevent back flow in the system while this inadequate pressure condition exists and until the pressure of the iiuid from the supply pump or other source has increased suiiiciently to meet the demands of the load on the hydraulic unit. These check valves, however, have the disadvantage of often opening suddenly when the required pressure has been reached, causing jerky operation and ineffective control of the hydraulic cylinder unit. `This condition likewise prevails in double acting hydraulic cylinder units; however, these latter units have the further disadvantage when controlled by the conventional directional valve of cavitating on the high pressure side of the piston as a result of a rapid and excessive withdrawal of hydraulic uid from the low pressure side of the piston. Check and poppet valves have also been employed in the conventional valves to control the return of fluid from the low pressure side; however, controlling the operations of the latter valves to obtain proper timing and smooth operation of the hydraulic cylinder has been diliicult and frequently ineffective. It is therefore one of the principal objects of the present invention to provide an eiiective, relatively simple and Compact directional control valve of the spool type for either single or double acting hydraulic cylinders, in which leakage of uid from the hydraulic cylinder, and consequently load drift, are positively prevented, and in which no load drop occurs in the hydraulic cylinder when the valve is actuated to operate the cylinder.

Another object of the invention is to provide a directional spool valve or double acting cylinders having a poppet and cheek valve mechanically actuated, hydraulically operated mechanism in the hydraulic fluid lines to each end of the cylinder, which facilitates accurate and eiective control of the hydraulic cylinder by the operator, and which prevents cavitation and avoids load drop at the beginning of and during the operation of the hydraulic cylinder.

Still another object is to provide a directional control spool valve having a pilot operated poppet valve which positively prevents leakage from the hydraulic cylinder unit while the unit is in the hold position, and in which continued use creates wear in and results in more effective operation, thus permitting wider manufacturing tolerances, both in the poppet and spool valve elements, reducing service requirements, and increasing substantially the life of the valve over conventional spool Valves.

A further object o the invention is to provide relatively easily fabricated directional control valves for either 3,125,120 Patented Mar. 17., 1964 single or double acting hydraulic cylinders and in either series or parallel` circuits, which are free of hunting and chattering, and which permit accurate, effective and reliable control of the cylinders, regardless of normal variations in available operating fluid pressures.

Another object of the present invention is to provide a comparatively simple and relatively inexpensive directional control valve having poppet valves in the lines to the cylinders, which will consistently open in response to moderate pump pressures regardless of load created back pressures.

Another object is to provide a novel poppet valve for use in directional control valves, which can be easily assembled and serviced and which can be effectively used in conjunction with a number of different types of basic control valves.

Additional objects and advantages of the present control valve will become apparent from the following description and accompanying drawings, wherein:

FIGURE 1 is a cross sectional View of a directional control valve of dual spool, in series arrangement and open center type, embodying my invention;

FIGURE 2 is a cross sectional view of the valve shown in FIGURE 1, taken on line 2 2 of the latter ligure, illustrating one form of my poppet valve and showing the spool valve in its neutral hold position;

FIGURE 3 is an enlarged cross sectional view of one of the poppet valves shown in FIGURE 2, taken on line 3 3 of said figure, showing the valve in a different operating position;

FIGURE 4 is a cross sectional View of a modified form of poppet valve embodying my invention, the section being taken on a line corresponding to the sectional view of FIGURE 2;

FIGURE 5 is a cross sectional view of another modiiied form of poppet valve embodying my invention; and

FIGURE 6 is a cross sectional view of a further modified form of valve, illustrating the present invention.

Referring more specifically to the drawings, numeral 10 designates the body of an open center valve having two spool valves 12 and 14 therein in series arrangement for controlling two separate double-acting hydraulic cylinders, one of which is diagrammatically illustrated at numeral 16. The two spool valves 12 and 14 contain spools or

plungers

13 and 15, respectively, andare supplied with hydraulic iluid from a pump or other suitable source (not shown) through a port 18, the fluid ilowing from port 18 through passage 20 to spool valve 12 and then through passage 22, to spool valve 14. The open center of valve 12 is connected with a tank return passage 24 and port 26 by

passages

22 and 28,

passages

20, 22 and 28 being in direct communication with one another when the two spool valves are in their neutral hold position, as shown in FIGURES 1 and 2. Spool valve 12 is connected with one end of cylinder 16 by passages 3@ and Sil and with the other end of the cylinder by

passages

32 and 32',

and spool valve 14 is connected with one end of another double actingcylinder (not shown) similar to cylinder 16 by passage 34 and with the other end of the respective cylinder by passage 36. Passage 20 is also connected to passage 24 for returning fluid to the tank through a pressure relief valve 40, the construction and operation of which will be described in greater detail hereinafter. The valve illustrated in the drawing is suitable for a variety of different types of hydraulic systems, the one shown being designed to control two double acting hydraulic cylinders of well known construction, and forming a part of a system having a tank and a positive displacement pump for supplying hydraulic iiuid from the tank to the valve and thence through the lines to both ends of the double acting hydraulic cylinders. The pump is continuously operating and the iiuid from the pump is returned directly to the tank while the valve spools are in their neutral hold position as shown in FIGURES l and 2. The hydraulic system and the components thereof, aside from the valve, form no part of the present invention and will not be described herein.

1n the spool valve 12, the bore has a series of lands separating the aforementioned passages for pump and tank fluid, including lands 51B and 52 between pump pressure passage 211' and open center fluid return passage 22 and passage 211 and passage 22, respectively, lands 511 and 56 between passage 211 and passage 36 leading to one end of the hydraulic cylinder and between passage 211 and pressure passage 32 leading to the other side of the hydraulic cylinder, and lands 58 and 611 between passage 30 and return passage 24 and between passage 32 and passage 241, respectively. On spool 13 are lands 62, 64 and 66 for controlling the flow of fluid through the open center connecting passages and 22 and from passage 2@ to

passages

30 and 32, and lands 63 and 711 for controlling the fluid return from passage 3i) to passage 24 and from passage 32 to passage 24, respectively. The spool is manually operated by a lever (not shown) connected to spool extension 72 and is returned to neutral hold position from either fluid delivery position by a centralizing means 74 consisting of a coil spring 76 disposed around an extension 7S of the spool, and reacting at one end against a retainer Sli seated against a shoulder 32 on the spool and shoulder 83 in the valve body, and at the other end against a spring retainer S4 mounted on the end of extension '7S and seating against cap 36- threadedly received in the valve body. As spool 13 is shifted, for example to the left as viewed in FIGURES 1 and 2, retainer 811 which is seated against shoulder 82 is moved with the spool, and since retainer 84 is held by cap 86, spring 76` is compressed, and on release of the spool by the operator, will return the spoolto its neutral- When the spool is shifted to the right,

hold position. spring retainer 84 is picked up by a collar 911 on extension 7S' and is moved with the spool, and since retainer 81B is seated against shoulder 33, spring 76 is thereby corn-k and passage 22" and passage 28, respectively, lands 941v and 96 between passage 22 and passage 34 leading to one end of a hydraulic cylinder and between passage 22" and pressure passage 36 leading to the other end of the hydraulic cylinder, and lands 93 and 1013 betweenl passage 34 and return passage 24 and between passage 36 and passage 24, respectively. On spool 15 are lands 1112, 14M and 1116 for controlling the iiow of uid through the open

center connecting passages

22 and 28 and from passage 22 to

passages

34 and 36, and lands 168 and 110 for controlling the fluid return from passage 34 to passage 24 and from passage 36l to passage 2d, respectively. The spool is manually operated by a lever connected to spool extension 112, and is held in any selected operating position by a detent mechanism 114 consisting of a hollow cap 116 -secured to body 16 in axial alignment with the bore of the spool valve and having a series of

annular grooves

118, 120, 122 and 124 in the internal surface a transverse bore 136 of the spool assembly and urged` radially outwardly by a coil spring 132 reacting at opposite ends against the two pins. As shown in FIGURE l, bore 131B is disposed in a cylindrical member 13e secured to the end of the spool -in axial alignment therewith by a stem 136 joined to the member and threaded into a recess 133 in the end of the spool. Various other types of detents than the one shown may be used in conjunction with spool valve 14.

Passages 3) and 32 for delivering fluid to the two ends of hydraulic cylinder 16'contain

poppet valves

150 and 152, respectively, of identical construction and operation, these two valves functioning to prevent leakage of fluid from the ends of the hydraulic cylinder, and consequently to prevent load drift while the valve is in the neutral position, and to avoid load drop by the hydraulic cylinder and cavitation in the cylinder while the cylinder is being operated. Since the two poppet valves are the same, only one will be described in detail, using the same numerals of one with primes to identify the parts of the other.v The two valves are seated in

cylindrical chambers

154 and 154 interposed, respectively, along the side of the spool between

passages

30 and 30 lead-ing to one end of hydraulic cylinder 16 and between

passages

32 and 32 leading to the other end of the cylinder, the

chambers having ports

156 and 156 defined by annular valve seats 158 and 15S and threaded connections 161i and 161i', respectively, for hydraulic fluid lines to the two ends of the cylinder.

Poppet valve consists of a hollow cylindrical element 162 havng a frusto-concally shaped surface 163 for engaging valve seat 158 and reciprocably supported in chamber 154 by a cup-shaped retainer 164, which in turn is supported by itsv outwardly extending flange 166 seated on shoulder 168 of the valve body. The flange, which is perforated or slotted at numerals 170 to permit the fluid to pass freely through chamber 154, is held rigidly against shoulder 168 by the hydraulic line coupling (not shown) threaded into connection 160. The hollow interior of element 162 is connected with passage 30 by an orifice 172 in the closed end of the element and with chamber 154 and consequently with passage 311 and one end of cylinder 16 by one or more small calibrated orifices 174 in the side of retainer 164 beyond the edge of element 162 when the element is in its seated position as shown in FIGURE 2. The ow of fluid through orifice 172 is controlled by a conically-shaped valve member 176 urged to its seat in the orifice by a coil spring 178 reacting against the internal side of the valve member and a cup-shaped retainer 186 in the hollow interior of element 162. The` spring also urges element 162 to its seat. A stem 182 is attached to valve member 176 and extends through oriiice 172 and passage 31D into contact with a shoulder 184 on the spool. Retainer 133 contains a number of longitudinal grooves 186 in the external side walls to permit the hollow interior of element 162 to communicate freely with orifices 174 when the element is not in its retracted position. When the spool is in its neutral hold position, as shown in FiGURE 2, stem 182 is perpendicular to the axis of the spool and radially outward from its reduced diameter portion 13S, and the valve member is in position to fully close orifice 172. As the spool is moved from neutral hold position to the left, shoulder 184 engages the free end of stern 132 and moves or swings it to the left, cocking and/or retracting valve member 176 sufiiciently to open orii ce 172 and permit high pressure fluid to flow from the interior of element 162 through

passages

30 and 24 and thence through port 26 to the tank. This reduction in pressure within element 162 permits the now higher pressure acting on conical surface 163 to fully retract the element from its seat to the position shown in FlG- URE 3.

In order to prevent chattering and hunting of valve element 162 while fluid is flowing through port 156 to the cylinder, orifices 174 are so placed with respect to the adjacent edge of element 162 that when the element is fully retracted from its seat the orifices are closed by the element, thus preventing momentarily the return of fluid into the hollow interior and consequently preventing the La. e)

return of the element to its seat by spring 17S. When the spool is returned to its neutral hold position blocking passage 311, fluid under back pressure from the cylinder in passage 30 and chamber 154 flows through a small orifice 19t) in the end of retainer 164 into the hollow interior of element 162 and with the assistance of spring 178 urges element 162 to its seat 158. In order to prevent fluid from bleeding through orifice 191i while the element is lifted from its seat, i.e. while fluid is being admitted into the respective end of the cylinder, a valve means 192, consisting of a ball seated in a recess in the adjacent end of retainer 180 and urged into the inner end of the orifice by spring 178, closes the orifice except when removed from its seat by the aforementioned back pressure immediately following return of the spool to neutral hold position.

In the operation of the foregoing spool valve structure 12 containing the poppet valves, movement of the valve to the left as viewed in FIGURES 1 and 2 blocks the open center passage 22 and connects passage 2G with passage 32 and simultaneously connects passage 3@ with passage 24. As the spool moves to the left, shoulder 184 engages the free end of stem 132, thereby opening valve 176 and permitting fluid to drain through orifice 172 from the interior of valve element 162. This reduces the pressure in the interior of the element sufficiently to permit the pressure on conical surface 163 within chamber 154 to unseat element 162 and permit fluid to flow from the respective end of cylinder 16. Simultaneously, fluid from the pump passes from passage 20 into passage 32 and reacts against the end of poppet valve element 162', first temporarily opening valve 176 and then lifting the element from its seat and retracting it until orifices 174 are fully covered by the edge of element 162. With the element in this position, the pressure on the external surface of element 162 is suiciently greater than the combined internal fluid pressure and pressure of spring 173 that the element remains in its fully retracted position as illustrated in FIGURE 3 as long as passages 2t) and 32 are in communication. As soon as the spool is returned to its neutral hold position by centralizing means 74, valve 176 closes, permitting the pressure in the interior of element 162 to become substantially equal to the pressure on its external surface, and hence permitting spring 178 to seat Vthe element and close port 156. Simultaneously, the back pressure in passage 32 and chamber 154 opens valve means 192' and fluid passes through orifice 19u', thereby increasing the pressure in the interior of element 162' sufficiently to permit spring 178 to seat the element and close port 156.

Pressure relief valve 4t) determines the maximum pump pressure available for operation of the hydraulic cylinders and consists of a sleeve 193 seated in a bore 194 in body 16 and held therein by a threaded cap 195. The sleeve contains a reciprocable hollow element 196 urged to its seat 198 by a coil spring 250 reacting between the internal side of the element and a fixed partition member 26H2 within the sleeve. When-the element is fully seated, it closes opening 204 in the en d of the sleeve, and when the element is open, i.e. retracted to the right as viewed in FIGURE l, opening 254 and aport 2636 along the side of the sleeve connect passage 2b with fluid return passage 24. The interior of element 196 is connected with passage 2@ by arestric'ted orifice 203 in the end ofthe element and with passage 24 by a tubular member 210 and

passages

212 and 214, the tubular member being rigidly supported by partition member 202 and having a restricted orifice 216 in the end thereof. The tubular member contains a ball valve 21S which controls the flow of fluid through orifice 216, and which is urged to its seat about the orifice by a coil spring 22) reacting at one end against the ball valve and at the other end against an adjustment means 222 for varying the pressure required to open the valve. When the pressure in passage 20 is less than the maximum pressure desired, element 1% remains seated about opening 204 and ball valve 218 remains seated about orifice 216, and the pressure in the interior of the element is equal to the pressure in passage 2f). If the pump pressure in passage 2@ and the interior increases suiciently to unseat ball valve 218, the pressure in the interior of the element immediately decreases, permitting the higher pressure in passage 20 reacting on the external end of the element to retract the element from its seat and establish communication through opening 294 and port 206 between passage 20 and fluid return passage 24, thus immediately reducing the pressure in passage 20. Fluid passing slowly through restricted orifice 268 again reestablishes an equilibrium in pressure between passage 20 and the interior of element 196 and spring 200 seats the element and fully 'closes opening 294.

In some instances in which the hydraulic cylinder is heavily loaded, shifting of the spool to its rightward position, thus opening poppet valve 152 and permitting fluid to drain from the respective end of the cylinder, permits the piston to advance at a greater rate than the delivery of fluid from the pump toV the opposite end of the cylinder. In the conventional control valve this condition produces cavitation in the end of the cylinder to which lines 31B and 31) are connected. In the present unit passage 36B is connected with the tank through chamber 154,

passages

239, 232 and 24, and port 26. A valve consisting of an element 234 urged to its seat 236 by a spring 238 at one end of passage 232 permits the flow of fluid from the tank, under the foregoing condition, and provides sufficient uid to the cylinder to prevent cavitation. Valve element 234 prevents the back flow of fluid from the cylinder through passages 230 and 232.

In FIGURE 4 a modified and simplified versiion of the present invention is illustrated, consisting of a chamber 240 interposed between passages 3f) and 30' and having an annular valve seat 242 and a hollow cylindrical valve element 244 with a conical surface 246 for engaging seat 242. Element 244 is supported by a cup-shaped retainer 243 rigidly secured in the end of chamber 24). The hollow interior of element 244 is connected by an orifice 250 with passage 36 and by a restricted orifice 252, with passage 35', the former orifice being controlled by a valve member 254 urged to its seat in the orifice by a coil spring 256 and opened by a stem 255 as the spool is moved to the left as viewed in FIGURE 4. An external coil spring 260 around the element is preferably provided to prevent or minimize hunting and chattering of element 244. When the valve member 254 is opened, the pressure in the interior of the element is reduced to sufficiently permit the pressure in chamber 241i acting on the external surface of the element to retract the element from its seat. When the spool is returned to its neutral hold position, the fluid flowing through orifice 252 equalizes the internal and external pressures on the element and thereby permits spring 256 to seat the element.

The modified form shown in FIGURE 5 is substantially the same as that shown in the preceding figure with the exception of the pilot valve; hence, like numerals are used to identify like parts. In this form a more positive seal is obtained between the pilot valve 262 and a valve seat 264 by the use of an O-ring 265 seated in an annular groove 266 in a disc-shaped part 26S of the valve. In the operation of this pilot valve, part 268 and the O-ring are lifted perpendicularly from their seat by a stem 270 sliding on an inclined surface 272 on the spool. The operation of this poppet valve is otherwise the same as the one shown in FIGURE 4.

FIGURE 6 discloses a further modified form of the present invention, consisting of a chamber 280 interposed between passages 3@ and 35 and having an annular valve seat 282 and a hollow cylindrical valve element 234 with a conical surface 236 for engaging seat 282.

Element 254 slides on and is supported by a cylindrical retainer S mounted rigidly in the end of chamber 289. The hollow interior of element 28d is connected by a tubular protrusion 29d and an orifice 292 with passage 3i? and by a restricted orifice 29d and the hollow interior of retainer 288 with passage 30', orifice 2552 being controlled by a ball valve 2% urged to its seat in the orifice by a coil spring 29d mounted on a guide pin 36) extending from retainer 233. The ball when fully seated at the bottom of protrusion 290 projects through orifice 292 and engages a tapered surface 302 on the spool for unseating the ball. An external coil spring 304 around the element is preferably provided to prevent or minimize hunting and chattering of element 284. When ball valve 2% is opened by tapered surface 302 as the spool is shifted to the left, the pressure in the interior of the element is reduced sufficiently to permit the pressure in chamber 280 acting on the external surface of the element to retract the element from its seat. When the spool is returned to its neutral hold position and the fiuid flowing through orifice 294 equalizes the internal and eX- ternal pressures on the element, spring 29d seats the element and closes the passage to the cylinder.

While four variations of the present poppet valve mechanism have been disclosed in detail herein, various other changes and modifications may be made to suit requirements, and the present valve mechanism may be used in various combinations of spool valve assemblies for both single and double acting cylinders, without departing from the scope of the invention.

I claim:

l. A valve for controlling the operation of a double acting hydraulic cylinder, comprising a body having a bore and a fiuid inlet and two fiuid outlet passages intersecting said bore, a spool in said bore extending through said outlet passages and having annular shoulders within said outlet passages, a poppet valve in each of said outlet passages, each including a cylindrical chamber with an annular valve seat defining a port and facing away from said spool, a cup-shaped element in said chamber having a conical surface engaging said seat and closing saidr port and having an orifice in the end adjacent to said port, a valve means for closing said orifice, a stem connected to said Valve means and adapted to be engaged by the shoulder on said spool for opening said valve means, a cup-shaped member rigidly mounted in said chamber for reciprocably receiving and supporting said element and having a restricted orifice in the side thereof closed by said element when the element is fully retracted from its seat and another orifice in the end thereof communicating with said chamber, a valve means for closing said last mentioned orifice, and a coil spring within said element reacting between both said valve means for urging said valve means and said element to their respective seats.

2. in a valve for ycontrolling the operation of a double acting hydraulic cylinder, a body having a bore and a fluid inlet and two fluid outlet passages intersecting said bore, a spool in said bore extending through said outlet passages and having shoulders within said outlet passages: a poppet valve in each of said outlet passages, each comprising a chamber with an annular valve seat defining a port and facing away from said spool, a hollow cylindrical element in said chamber having a surface engaging said seat and closing said port and having an orifice in the end adjacent to said port, a valve means for closing said orifice, a stem connected to said valve means and adapted to be engaged by the shoulder on said spool for opening said valve means, a means for reciprocably receiving and supporting said element and having a restricted orifice in the side thereof closed by said element when the element is fully retracted from its seat and another orifice in the end thereof communicating with said chamber, a valve means for closing said last mentioned orifice, and a spring means rei acting between both said valve means for urging said valve means and said element to their respective seats.

3. A valver for controlling the operation of a hydraulic cylinder, comprising a body having a bore and a fluid inlet and a fiuid outletl passage intersecting said bore, a spool in said bore extending through said outlet passage and having an annular shoulder within said outlet passage. a poppet valve in said outlet passage including a cylindrical chamber with an annular valve seat defining a port and facing away from said spool, a hollow cylindrical element in said chamber having a surface engaging said seat and closing said'port and having an orifice in the end adjacent to said port, a valve means for closing said orifice, a stem connected to said valve means and adapted to be engaged by the shoulder on said spool for opening said valve means, a cup-shaped member rigidly mounted in said chamber for reciprocably receiving and supporting said element and having a restricted orifice in the side thereof closed by said element when the element is fully retracted from its seat and another orifice in the end thereof communicating with said chamber, a valve means for closing said last mentioned orifice, and a coil spring within said element reacting between both said Valve means for urging said valve means and said element to their respective seats.

4. In a valve for controlling the operation of a hydraulic cylinder, a body having a bore and a fluid inlet and a fiuid outlet passage intersecting said bore, a spool in said bore extending through said outlet passage and having a laterally extending surface within said outlet passage: a poppet valve in said outlet passage, comprising a chamber with a valve seat defining a port and facing away from said spool, a hollow cylindrical element in said chamber having a surface engaging said seat and closing said port and having an orifice in the end adjacent to said port, a valve means for closing said oritice, a stem connected to said valve means and adapted to be engaged by said surface on the spool for opening said valve means, a means for reciprocably receiving and supporting said element-and having a restricted orifice in the side thereof closed by said element when the element is fully retracted from its seat and another orifice in the end thereof communicating with said chamber, a valve means for closing said last mentioned orifice, and a spring means reacting between both said valve means for urging said valve means and said element to their respective seats.

5. In a valve for controlling the operation of a hydraulic cylinder, a body having a bore and a fiuid inlet and a fiuid outlet passage intersecting said bore, a fiuid control means in said bore extending into said outlet passage and having a laterally extending surface within said outlet passage: a poppet valve in said outlet passage, comprising a chamber with a valve seat defining a port and facing away from said control means, a hollow cylindrical element in said chamber having a surface engaging said seat and closing said-port and having an orifice in the end adjacent to said port, a valve means for closing said orifice, a means adapted to be engaged by said surface on the control means for opening said valve means, a means for reciprocably receiving and supporting said element and having a restricted orifice inthe side thereof closed by said element when the element is fully retracted from its seat, and a spring means for urging said valve means and said element to their respective seats.

6. A valve for controlling the operation of a hydraulic cylinder, comprising a body having a bore and a fiuid inlet and a fiuid outlet passage intersecting said bore, a fluid control means in said bore intersecting said outlet passage and having a laterally extending surface, a poppet valve in said outlet passage, comprising a chamber with a valve seat defining a port and facing away from said control means, a hollow cylindrical element in said chamber having a surface engaging said seat and closing said port and having an orifice in the end adjacent to said port, a valve means for closing said orifice, a means adapted to be engaged by said surface on the control means for opening said valve means, a means for reciprocably receiving and supporting said element and having a restricted orifice in the side thereof closed by said element when the element is fully retracted from its seat and another orifice in the end thereof communicating with said chamber, a valve means for closing said last mentioned oriice, and a spring means for urging said valve means and said element to their respective seats.

7. In a control valve, a poppet valve, comprising a means defining a chamber and a valve seat therein, a hollow cylindrical element in said chamber having a conical surface engaging said seat and having an orifice in the end adjacent said seat, a valve means for closing said orifice, a means for opening said valve means, a cup-shaped member for reciprocably receiving and supporting said element and having a restricted orifice in the side thereof closed by said element when the element is fully retracted from its seat and another orice in the end kthereof communicating with said chamber, a valve means for closing said last mentioned oritice, and a spring means for urging said valve means and said element to their respective seats.

References Cited in the le of this patent UNITED STATES PATENTS 1,390,851 Winckeler Sept. 13, 1921 2,592,906 Jirsa et al. Apr. 15, 1952 2,644,429 Waterman et al. July 7, 1953 2,821,211 Wittren Jan. 28, 1958 2,969,044 Leduc Jan. 24, 1961

Claims

5. IN A VALVE FOR CONTROLLING THE OPERATION OF A HYDRAULIC CYLINDER, A BODY HAVING A BORE AND A FLUID INLET AND A FLUID OUTLET PASSAGE INTERSECTING SAID BORE, A FLUID CONTROL MEANS IN SAID BORE EXTENDING INTO SAID OUTLET PASSAGE AND HAVING A LATERALLY EXTENDING SURFACE WITHIN SAID OUTLET PASSAGE: A POPPET VALVE IN SAID OUTLET PASSAGE, COMPRISING A CHAMBER WITH A VALVE SEAT DEFINING A PORT AND FACING AWAY FROM SAID CONTROL MEANS, A HOLLOW CYLINDRICAL ELEMENT IN SAID CHAMBER HAVING A SURFACE ENGAGING SAID SEAT AND CLOSING SAID PORT AND HAVING AN