US2381795A - Hydraulic control mechanism - Google Patents

Description

Aug. 7, 1945. w. F. WILLI-:TTv I 2,381,795 I HYDRAULIC CONTROL MECHANISM Filed Feb. 14, 1941 4 Sheets-Sheet 2 Aug. 7, 1945. w. wlLLETT 2,381,795

HYDRAULI C CON TROL ME CHANI SM Filed Feb. 14, 1941 4 Sheets-Sheet 3 Aug. 7, 1945, w. P. WILLETT 2,381,795

- HYDRAULIC CONTROL MECHANISM A Filed Feb. 14, 1941 4 sheets-sheet 4 v INVENTOR.

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Patented Aug. 7, 1945 wonen P. wine, 'raam ruk,

Hd., signor corporsted, Detroit, Mich.; a corhigan to Vickers, In poration o! Mic Application February 14, 1941, Serial No. 378,920

ummm. (otto-ss) 'This invention relates to a hydraulic control mechanism.

It is an objectY of the presentinvention to provide a control mechanism for a hydraulic circuit in which movement is started by the shifting of a hand lever and stopped automatically by a control mechanism at a predetermined point in the movement of the device being controlled. The invention contemplates a servo-*control used incombination with the control device so that the speed of the member being controlled may be regulated by the operato Another feature of the invention has to do with-an automatic means for venting the operating lines at the completion of a cycle thereby obviating any tendency for the output shaft to creep. due to imperfect centering of the variable displacement pump which is used in the system.

' A further object of the invention is to provide a hydraulic circuit which may be stopped,

started, or reversed at any point in the cycle of the operation. Provision is also made for the operation of the control elements by hand in the event that there'is pressure failure in the servocontrol mechanism.

Other objects and features of the invention relating to details of the circuit and operating means therefor, will be apparent in the following description and claims.

In the drawings:

Fig. 1 illustrates the circuit of the present invention'with the parts in the position which follows the reversal movement after the hand lever has been moved back to neutral.

Fig. 1A is a side view of the brake mechanism shown in Fig. 1.

Fig. 2 shows the circuit with the parts as they would be positioned near the beginning of a forward movement but after the pump has been advanced to its full volume position by the control mechanism.

Fig. 3 shows the circuit at the end of the iorward movement before the hand lever has been returned to neutral.

Fig.`4 shows the circuit with the parts in their position near the bezinning of a reversing movement but after the pump has been advanced to its full volume position by the control mecha- I'he system as shown is particularly adapted tovarious typesofmachinery butisespecially' suitable for drivingordnance equipment such as ammunition hoists and remmers. The circuit shown is particularly adapted for a rammer andv u wm be desonbed in connection with o, ramming movement and a retractins movement. al-

though the rammer mechanism is not shown.

The main elements of the circuit include an electric motor' Il which drives a reversible variable pump II. The pump H furnishes liquid under pressure to a hydraulic motor I2 which has an operating shaft il. A braking wheel Il is mounted on shaft Il and a brake shoe II is connected to a bellcrank Il operated by 'a piston H.

` The elengents o! the control for the hydraulic circuit include ilrst, a movable member 2l on pump il which controls the rate and direction of ilow through the pump according to its displacement from center. A valve 2| operated by a hand lever 22 controls the position of a piston 23 which actuates the movable memberll. Hand lever 22 has a ram position as shown and a rego tracted position.` -A rod 24 and a spring 2i connect the hand lever with a lever 2l which is connected at one end to the member 2l and the other end to a link 21 and rod :l leading to the valve 2|. A piston rod 2l on piston 2l is con- 25 nectedv to the other end of lever 2B and also is 3o threadV back 35 timing valves 31 40 duits 4s onoas. conduit u 4l duits 41 and' 4l. Valve connected to a lever It which serves as part of an automatic control for decelerating and stop. ping the motor l2.

Lever Il is operatedby nuts Il and 32 which and forth driven by power shaft il through bevel gears. The nuts Il and 32 are notched and slide on a bar Il to prevent their turning. Rod I3 also has cams 35 and It which actuate. respectively, and ll in a housing Il. A valve 4i in housing 42 is also arranged to be actuated bytbenuts li andninamannerwhich willbe described in detail.

Pump Il is connected to motor I2 by two conwill be under pressure during the ramming stroke while conduit 4i will be under pressure during the retraction stroke. These conduits are connected to the respective ends of the bore in housing 42 by conis so arranged that when either conduit 4I or Il is underpressure. valve 4i will be shifted by the pressure which passesto the valve housing through conduits l1 and I port III being connected byaconduittl tovalvelandaporti! being connected by a conduit Il to valve-ll. A center port Il is'connected to a conduit It. Conduit which may be known as a bypass conduit, passesthrough a restricted portion l1 oi' valve 0n a threaded rod Il' Valve ll is connected up hydraulically with valves l1 and Il, a

2| and the valve is properly positioned to a bypass valve 58 which is controlled by a cam 59 on rod 29. Conduit 56 is also connected to spring pressed piston |1 of the brake mechanism by a conduit 60 so that when the bypass conduit is blocked by either valve 2| or 58, pressure will build up in the system and release the brake. With the bypass line vented throhgh both valves 2| and 58 as shown in Fig. 1, a spring 6| acting on piston |1 will engage the brake. Conduits 65 and 66 connect respectively, the pressure conduits 45 and 46 with the bypass conduit 56 through check valves 61 and 68.

At the left end of valve 2| a restriction 18 forms a valve which controls conduits 11 and 18 which are connected respectively, with valves 31 and 38. A pilot pump 88, driven by motor |8, directs pressure through pilot line 8| to valve 2| 'where it may pass a restriction 82 or 83 to conduits 84 or 85 respectively, leading to the opposite sides of piston 23. A branch conduit 86 leads to a spring pressed valve 81 which is normally held in the position shown by pilot pressure. In the event of failure of pilot pressure, valve 81 shifts to the left to bypass lines 84 and 85. A relief valve 88 controls the pilot pressure while valves 98 and 9| connect the pilot line 8| respectively, with lines 45 and 45 of the main circuit. Restrictions 92 and 93, leading to check valves 88 and 8| prevent the diversion of the entire flow of the pilot pump to the main circuity when the main circuit is vented.

In the operation, Fig. 1 illustrates the parts at the end of a reverse movement with the manual lever 22 in neutral position. To initiate a ram or forward movement, the lever 22 is moved ahead, as shown in Figs. 2 and 3. The position of lever 26 at the beginning of the movement is shown in Fig. 3 wherein the valve 2| is shifted so that pilot pressure from line 8| may pass to.

line 85 and shift piston 23 to the left. During the initial movement of lever 26 it has pivoted at its lower end on the link connected to member 28. As the piston 23 starts to move to the left, lever 26 will pivot about its center mounting thereby returning valve 2| to neutral. Consequently, the piston 23 will move in a follow-up manner in a degree proportional to the displacement of the lever 22 toward the ram position but at the end of the movement of piston 23, the valve 2| will be in neutral position, as shown in Fig. 1. The pump will then deliver to the motor at the capacity at which it is set as shown in Fig. 2 until nut 32 engages lever 38 to move it from its Fig. 2 position to its Fig. 3 position. In the movement of the piston 23 to the left, cam 59 is shifted to the left thereby permitting the valve 58 to drop and close conduit 56 from the tank. Meanwhile, pressure is building up in conduit 45 due to the displacement of the movable member 28. This pressure will react through conduit 41 to shift valve 4| to its extreme right position. The shifting of valve 2| to the left will also block the vent in conduit 56, thereby causing pilot pressure to be built up above piston |1 to release the brake shoe I5. After motion has started, cam 58 will have moved to the left where it allows valve 58 to close and maintain the blocking of the vent in conduit 58. In this manner the subsequent shifting of valve 2| is rendered ineffective as a means of engaging the brake until the recentering of pump 28 has returned cam 58 toopen the valve 58. The shifting of valve 4| to the position shown in Fig. 2, blocks the center port 55 and thereby prevents bypassing of line 55 through either of the valves i 31 or 38. As the forward movement progresses, nuts 3| and 32 will shift to the left. Near the end of the cycle, nut 32 will contact the lower end of lever 38 and move the piston 23 and movable member 28 gradually back to neutral position. This position is shown in Fig. 3. Since the spring 25 is provided in rod 24, there will be a force on lever 25 which will shift valve 2| to the left again, as shown in Fig. 3 (provided the control lever is manually held in the Ram" position shown). Liquid to the right of piston 23 will thus be forced into lines 35 and 3| with check valve 33 taking care of volume displacement. Pressure from line 3| can not shift piston 23 since it is blocked by the nut 32. In the event the control lever is released during the deceleration and stopping action, it will follow the movement of pump 28 to neutral. Nut 3| in traveling to the left, will shift valve 4| slightly to the left to open center port 55 to port 52 in line 53. After this opening, when cam 35 reaches the point where valve 33 is open. as shown in F18. 3. the pressure in bypass line 53 will be transferred through line 13 to the tank around the restriction 13 in valve 2|. This path is shown in Fig. 3. Bypassing of line 55, of course. relieves pressure on the piston |1 and applies the brake. It also relieves any pressure that might remain in lines 45 or 43 due to imperfect centering of the member 28. There will, therefore, be no further movement of the shaft I3.

To effect reversal or retraction, the members are shifted as shown in Fig. 4 with valve 2| being moved first to the right where it will admit liquid from line 8|, to the left hand end of the piston 23 and shift it to the right, after which, due to movement of the piston, the valve 2| will be re-centered. During the retraction movement valve 4| is in the extreme left position blocking the center port until at the end of the movement, as shown in Fig. 1, the nut 32 shifts the valve to open the center port to port 53 and valve 31 which will bypass line 55 to line 11 and the tank, thereby stopping the system. At the end of the reversal, the nut 3| will shift the lever 38 back to its upright position, as shown in Fig. 1.

1. In a hydraulic variable speed transmission system for driving a load device, a variable speed transmissing including a pump member and a motor member, a pressure responsive movable part on one of said members for varying the output speed and the direction of the transmission, lines connecting said pump member and motor member, each adapted to serve alternately as pressure and return lines, control means for the movement of said transmission comprising a manual control member, hydraulic means responsive to movement to said member for shifting said movable part to a position whereby pressure is directed through said transmission, andl means responsive to a predetermined movement of said motor lfor shifting said movable part gradually back to a neutral position independently of said hydraulic means.

2. In a hydraulic mechanism, a reversible variable delivery pump with a movable control head for volume and directional control, a. reversible motor to be driven by pressure from said pump, lines connecting said pump and motor, each adapted to serve alternately as pressure and return lines, control means for the movement of said motor comprising a manual control mem assnvos 3 ber havingneutral and actuating positions, hydraulic means responsive to movement oi' said member for sluiting said pump control head to a position whereby pressure is directed to said motor, means responsive to la predetermined movement 'ot said motor. i'or sluiting saidhead gradually -back to a neutral position independentlv of said hydraulic means, means responsive to said motor movement to bypass said lines after s predetermined movement Vto prevent further trol member remains in actuatins position, and additional means Vfor bypassing said lines when said control member is in neutral position.

3. In a hydraulic mechanism, a reversible variicr volume control. a reversible motor to be driven by pressure from said pump, lines connecting said pump and motor, each adapted to serve alternately as pressure. and return lilies,v control means for the movement ci said motor comprising a manual control member, yhydraulic;means responsive to movement of said member iorshittingsaid pump control headto'a position whereby pressure is directed to said motor, means rasive to said motor movement to bypass said lines to 'prevent further movement Y of said motor, 'said additional means being responsive to pressure in one or the other of said lines and arranged to be reset by said pressure attireV start oi'va cycle oi' movement of said motor.

4. In a hydraulic mechanism, a reversible variable delivery pump with' a movable control head for volume control, vc. reversible motor to'be driven by pressure from said pump, lines connecting said pump and' motor, each adapted'A to serve` alternately as pressure and return lines,.co ntrcl means for thev movement of said motor comprising a manuall control member, hydraulic meansv responsive to movement oi' said member for shitting said pump control head to a positionwhereby pressure is directed to said motor, means responsive to a predetermined movement of said motor'iorv shifting said head gradually back to a neutral' position comprising a rotating shaft driven by said motorpnuts on said shalt. means for holding said nuts against rotation but permitting axial movement relative to the shaft, a lever to be actuated by one or the other ci said nuts, and means connecting said lever and lsaid control head whereby upon predetermined movement of said motor, said control headwill be moved back to a neutral position.

5. In a hydraulic mechanism, a reversible variable delivery plump with a movable control head for volume control, a reversible motor to be driven by pressure from said pump. lines connecting said pump and motor, each adapted to serve alternately as pressure and return lines, control means for the movement of said motor comprising a manual control member, hydraulic means responsive to movement of said member for shifting said is directed to said motor, means responsive to a predetermined movement of said motor for shiftby one or the other of. said nuts, means connecting said lever and said control head whereby 7s shaft driven by said motor, nuts on said shaft,

, 65 said um and motor, each pump control head to a position whereby pressure p p l further movement oi' said motor.

6. In a hydraulic mechanism, a reversible-variable delivery pump with a movable control head l for volume control, a reversible motorl to be driven by pressureirom said pump, lines ccn-d 10 necting said pump and moton'each adapted to movement of said motor when said manual conserve alternately as pressure and return! lines, control means tor the movement ot said motor comprising a manual control member, hydraulic means responsive to movement of said member lil for shifting said pump control head to a position able delivery pump with a movable control head 20 driven by said motor, nuts on said shaft, means for holding said nuts against rotation but permitting axial movement relative to the shaft, a lever to be actuated by one or the other of'said nuts, means connecting said lever and said conv V "2B trol head wherebyuponpredetermined movement sponsive to a predetermined movement oi-s aid Y motor for shifting' saidhead. gradually hack to a neutral position, and additional means'respona lo motor, said additional means being responsive to pressure in one or the other oi' said lines and arranged to be reset by said pressure at the start lroi' a cycle of movement of said motor.

A '1. In a hydraulic mechanism, a reversible vini--vv 88 iable delivery pump with a. movable control head for Evolume control, a yreversible motor to be driven: by pressure'irom said'pump, lines connecting said pump and motor, each adapted to ,serve alternately as pressure and return lines,

' t0 means for the movement oisaidV motor comprising a manual control member, hydraulic means responsive to movement of said member for shitting said pump control-head `to a position whereby pressure" is `directed to said motor,

45 means responsive to a predetermined movement ci! said motor for shitting said head gradually back to a neutral position, additional means responsive to said motor movement to bypass said es to prevent further movement oi' said motor,

5.0 comprising conduits connecting said lines and a series oi' valves in said conduits including a. slow moving valve actuated by said motor and a fast moving valveactuated by said motor. and means connecting said valves and said motor whereby, 55 upon a predetermined movement of said motor,

said slow valve will have shifted to open said bypass lines and, at a predetermined point in the rotation oi said motor, said fast valve willalso be moved to open said bypass lines thereby so preventing further movement of said motor.

8. In ahydraulic mechanism, a reversible variable delivery pump with a movable control head for volume control, a reversible motor to be driven by pressure from said pum adapted to serve alternately as pressure and return lines, control means for the movement of said motor comprising a manual control member, hydraulic means responsive to movement'` of said member for 70, shit-ting said pump control head to a position whereby pressure is directed to said motor,

means responsive to a predetermined movement I of said motor for shifting said head gradually back to a neutral position comprising a rotating lines connectingmeans for holding said nuts against rotation but permitting axial movement relative to the shaft,

a lever to be ac-tuated by one or the other of said nuts, means connecting said lever and said control head whereby upon predetermined movement of said motor, said control head will be moved ba'ck to a neutral position, additional means responsive to said motor movement to bypass said lines to prevent further movemen-t of said motor, comprising conduits connecting said lines and a series of valves-in said conduits including a slow moving valve actuated by said motor and a fast moving valve actuated bysaid motor, and means connecting said valves and said motor whereby, upon. a predetermined movement of said motor, said slow valve will have shifted to open said bypass lines and, at a predetermined point in the rotation of said motor, said fast valve will also be moved to open said bypass lines, thereby preventing further movement of said motor.

9. In a hydraulic mechanism, a reversible variable delivery pump with a' movable control head for volume control, a reversible motor to be driven by pressure from said pump, lines connecting said pump and motor, each adapted to serve alternately as pressure and return lines. control means for the movement of said motor comprising a manual control member, hydraulic means responsive to movement of said member for shifting said pump control head to a position whereby pressure is directed to said motor, means responsive to a predetermined movement of said motor for shifting said head gradually back to a neutral position comprising a rotating shaft driven by said motor, nuts on said shaft, means for holding sa.id`\nuts against rotation butv permi-tting axial movement relative to the shaft/a lever to be actuated by one or the other of said nuts, means connecting said lever and said control head whereby upon predetermined movement of said motor, said control head will be moved back to a neutral position, additional means responsive to said motor movement to bypass said lines to prevent further movement of said motor, comprising conduits connecting said lines and a series of valves in said conduits including a slow moving valve actuated by said motor and a fast moving valve actuated by said motor, and means connecting said valves and said motor whereby, upon a predetermined movement of said motor, said slow valve will have shifted to open said bypass lines and, at a predetermined point in the rotation of said motor, said fast valve will also be moved to open said bypass lines, thereby preventing further movement of said motor, said slow valve being responsive to pressure in one or the other of said lines and being reset by said pressure at the start of a cycle of movement of said motor.

10. In a hydraulic mechanism, a reversible variable delivery pump with a movable control head for volume control, a reversible motor to be driven by pressure from said pump, lines connecting said pump and motor, each adapted to serve alternately as pressure and return lines, control means for the movement of said motor comprising a manual control member, hydraulic means responsive to movement of said member for shifting said pump control head to a position whereby pressure is directed to said motor, means responsive to a predetermined movement of said motor for shifting of said head gradually back to a neutral position, additional means responsive to said motor movement to bypass said lines to prevent further movement oi' said motor, comprising conduits connecting said lines and a series of valves in said conduits including a slow moving valve actuated by said motor and a fast moving valve actuated by said motor, and means connecting said valves and said motor whereby, upon a predetermined movement of said motor, said slow valve will have shifted to open said bypass lines and. at a predetermined point in the rotation of said motor, said fast valve will also be moved to open said bypass lines thereby preventing further movement of said motor, said slow valve being responsive to pressure in one or the other of said -lines and being reset by said pressure at the start of a cycle of movement oi said motor.

Y WARREN P. WIILETI.

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