US2962001A - Hydro-pneumatic power mechanism - Google Patents

Description

Nov. 29, 1960 R. D. MoRToN E rAL 2,962,001

HYDRO-PNEUMATIC YPOWER MECHANISM Filed Nov. 7, 1958 .'5 Sheets-Sheet 1 NOE mw ww mw NOV. 29, 1960 R, D, MORTQN ETAL 2,962,001

HYDRO-PNEUMATIC POWER MECHANISM Filed Nov. 7, 1958 3 Sheets-Sheet 2 52 98 @2 By EDWARD aGRoHos/f/ NOV. 29, 1960 R, D, MORTON ETAL 2,962,001

HYDRO-PNEUMATIC POWER MECHANISM Filed Nov. '7, 1958 3 Sheets-Sheet 3 FIG@ 95 93 INVENTORS ROBERT a. MoRTo/v BY En WARD c. GRn/105m HYDRO-PNEUMATIC POWER MECHANISM Robert D. Morton, West Hartford, and Edward G.

Grohoski, Torrington, Conn., assignors to The Hartford Special Machinery Co., Hartford, Conn., a corporation of Connecticut Filed Nov. 7, 1958, Ser. No. 772,527

6 Claims. (Cl. 121-45) The present invention generally relates to hydro-pneumatic power mechanisms and more particularly to an improved construction and control system therefor.

It is an object of this invention to provide a power mechanism having an improved air and hydraulic piston and cylinder arrangement which permits substantial reduction in the over-all dimensions of the mechanism as well as a greatly simplified control arrangement.

It is a further object of this invention to provide a hydro-pneumatic power mechanism having an improved positive shaft-travel stop that is concentric with the spindle so as to avoid bending moments as it stops shaft travel and to provide a wide range of adjustment for this stop in a greatly simplified manner.

It is an additional object of this invention to provide a hydro-pneumatic power mechanism in which separate pistons are provided for the hydraulic and pneumatic sections and in which the pistons and cylinders are concentric with the power shaft so as to avoid shaft bending moments and permit placing of the valving and tubing relating to each section adiacent its concerned piston and cylinder.

It is a still further object of this invention to provide a power mechanism having an improved hydroepneumatic power and control system which is easily adaptable to provide hydraulic as well as air feed for the power shaft.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

Fig. 1 is a longitudinal cross-sectional view of a preferred embodiment of the power mechanism of this nvention;

Fig. 2 is a partial cross-section view showing a portion of the hydraulic control mechanism of Fig. 1 taken generally along the lines 2-2 of Fig. 3;

Fig. 3 is a partial cross-section view of the mechanism of Fig. l taken along the lines 3 3 of Fig. 2;

Fig. 4 is a schematic representation of the mechanism of this invention and a preferred control circuit therefor;

Fig. 5 is a schematic representation of the power mechanism of this invention during a portion of its operative cycle; and

Fig 6 is a schematic representation of an additional embodiment of this invention showing a modified control system therefor.

In accordance with the objects of this invention, a mechanism, as shown in Figs. 1, 2, and 3, is provided with a main frame or housing 10 which slidably supports a longitudinally movable quill or carriage member 11 on support pedestals 12 and 13. Power shaft 18 is rotatably supported in coaxial alignment with quill 11 by bearings 19 and 20 which are suitably fixed in position and longitudinal movement of shaft 18 relative to quill 11 is pre- Patent O ice In order to provide for powered movement of quill 1,1`

and shaft 18, a first or air cylinder 28 is provided within frame 10 and having end walls 29 and 30 and peripheral` wall 31 arranged coaxially with quill 11. Air piston 33 is secured to quill 11 and is provided with packing 34 around its outer periphery to effect a sliding seal with peripheral wall 31 of air cylinder 28. Suitable packing is also provided at points 15 and 16 to effect a sliding seal between quill 11 and support pedestals 12 and 13. End walls 29 and 30 of cylinder 28 are spaced to permit the desired amount of spindle 18 (and therefore quill 11) travel under air pressure exerted on piston 33 as is subsequently explained.

The control of movement of quill 11 by air pressure on piston 33 is accomplished by the provision of a second cylinder 40 within frame 10 and coaxial with quill 11. Cylinder 40 is provided with end walls 41 and 42 and peripheral wall 43 all arranged coaxially with quill 11. A second or hydraulic piston 44 is secured to quill 11 and is provided with peripheral packing 45Vwhich effects a sliding seal with peripheral wall 43. Hydraulic cylinder end walls 41 and 42 are also spaced apart by an amount at least equal to the desired amount of longitudinal travel of spindle 18.

The coaxial arrangement of spindle 18, quill 11, air cylinder 28 and hydraulic cylinder 40 provides a very compact arrangement of mechanical parts and greatly simplifies the arrangement of control valving and piping. As most clearly seen in Figs. l and 4, a main air valve 50 is positioned in frame 10 directly below air cylinder 28 so that line 51 directly communicates with the front face of air piston 33 and line 52 directly communicates with the rear face of air piston 33 thereby enabling these lines to be very short in length.

In a similar manner to the main valve of the air circuit, the main hydraulic valve 60 is positioned in frame 10 directly beneath hydraulic cylinder 40 so that hydraulic lines 61 and 62 have a short direct path of communication therewith. In addition, forward feed valve 65 is also conveniently positioned adjacent hydraulic valve 60 in frame 10 and is arranged so that control shaft 66 extends through the front of frame 10 so that forward feed rate adjusting knob 67 is easily accessible to the machine operator.

The forward travel limit of quill 11 is determined by an adjustable stop mechanism most clearly seen in Fig. l. A stop tube 70 is positioned coaxial with quill 11 at a point intermediate quill 11 and drive tube 25. Stop tube 70 is rotatably supported by rear pedestal 9 of frame 10 and is provided with stop ring or abutment 71 adjacent its forward end. The internal surface of quill 11 is partially threaded along portion 72 so that these threads engage complementary threads formed on stop nut 73 which is keyed to stop tube 70 at point 74. Thus, rotation of stop tube 70 rotates stop nut 73 so as to selectively position it along threaded portion 72 of quill 11. As is apparent, the closer stop nut 73 is positioned to stop abutment 71, the shorter the amount of travel possible for quill 11 before stop nut 73 and stop abutment 71 engage each other. Adjustment of stop nut 73- is accomplished by rotating knurled adjusting ring 75 which is rotatably supported by rear abutment 9 and which is internally threaded so as to engage pinion 76 which, in turn, engages gear 77 secured to the rear endy of stop tube 70. In the preferred embodiment, gear 77 Patented Nov. 29, 1960I is formed of a nonconducting material and is provided with a conductive ring which is normally held away from engagement with support 9 by a small leaf spring 78. The conductive ring on gear 77 engages brush 79 to establish `electrical Contact with spring 81 thereafter to contact brush 82 so as to establish an external electrical connection point. As will be hereinafter described, engagement of stop nut 73 with stop abutment 71 causes slight axial movement of the conductive ring on gear 77 against the force of spring 78 and into contact with rear support 9 thereby to ground brush 82 and the external connection point to frame 10.

The normal operation of the aforementioned air and hydraulic control structure calls for a two-step pattern of quill movement. For example, if quill 11 is assumed to be in the position illustrated in Fig. l and to be carrying a work tool such as a drill in chuck portion 18a (shown dotted) of spindle 18, it is most desirable that the power mechanism rapidly advance quill 11 to a point at which the drilling operation is to commence. When this drilling point is reached, it is desirable to automatically stop such rapid feed and then to provide a slower controlled feed rate of advance for quill 11 which is predetermined as an optimum drill advance speed. At the completion of the drill travel as determined by the stop nut adjustment, it is desirable to rapidly return the spindle to the position shown in Fig. l.

In furtherance of these control aims, a pair of control rods (most clearly seen in Figs. l, 2, and 3) are provided for travel with quill 11. Control rod 90 is secured by screw 91 to control rod frame 92 which, in turn, is supported on quill 11 by threaded fasteners 93 and 94. Control rod 95 is positioned on the other side of frame 10 and is supported thereon by control rod frame 92 in a manner similar to that described for rod 90. Rod 90 carries trip dog 96 which is slidably positioned along flat portion by set screw 99. Axial movement of quill 11 will bring trip dog 96 into contact with operating button 97 of poppet valve 98. In a similar manner, rod 95 adjustably carries trip dog 100 which controls the operation of poppet valve 101 as it contacts operating button 102. It is worth while to briefly note at this point that each poppet is connected by air tubing to respective ends of hydraulic valve 60 and that air pressure is applied at all times to the opposite ends of the valve spool. Since the ends of the valve spool are of the same diameter, the spool will remain stationary until the air is suddenly exhausted from one end. For this purpose, the poppet valves are vented to the atmosphere so that actuation of one or the other of the poppet valves momentarily lowers the pressure on that end of the hydraulic valve so as to cause the spool to shift in position to open and close the valve as a function of quill position.

The operation of the power mechanism of the preferred embodiment of this invention is best understood by referring to Figs, 4 and 5. Starting with quill 11 in its fully retracted position and solenoid valve 53 in its normally energized position (as shown), it is seen that air pressure from any suitable supply source 49 is supplied to main air valve 50 through line 110 to a point intermediate pistons 111 and 112 of valve spool 113 as well as to face 114 of piston 115. Since line 116 (and therefore face 118 of piston 115) is vented through exhaust port `48 of solenoid valve 53, spool 113 is driven against stop 117 because of the pressure differential between faces 114 and 118 of spool 113. With the air valve in this position, air under pressure is supplied from line 110 through line 51 to the forward face of piston 33 and line 52 is vented through exhaust port 120 on valve 50. Air is also supplied to the opposed equal area faces 121 and 122 of hydraulic valve 60 through line 123. Because of the equal areas of these faces and the equal pressures applied thereto, valve 60 remains against stop 68 in the position shown. In addition, face 122 directly communicates with poppet 4 valve 98 through line 124 and face 121 directly communicates with poppet valve 101 through line 125.

The hydraulic system including cylinder 40, lines 61 and 62, and the intermediate valving, is lled with an appropriate fluid and it is seen that movement of piston 33 under air pressure tends to force that hydraulic tiuid from in front of hydraulic piston 44 and through line 62. As seen in Fig. 4, check valve 170 prevents fluid ow into reservoir 171 and check valve 127 prevents fluid return directly to cylinder 40 around valve 60. In addition, considerable resistance is offered to fluid flow through feed valve 65 and check valve 131 because ofthe restricted orifice in valve 65. However, because hydraulic valve 60 is in a position wherein line 62 directly communicates with line 61 through line 126, there is no impediment to the movement of quill 11 in the directon of the arrow of Fig. 4. The spindle, therefore, starts the rapid advance portion of its cycle. As the advance continues to the point where trip dog 100 engages operator 102 of poppet valve 101 (see Fig. 5, solid line position) so as to vent line 125, it is seen that an unbalanced pressure condition on the spindle of valve 60 exists which moves the spool of valve 60 to the right so as to close the unobstructed path of communication between lines 62 and 61, namely, line 126. The hydraulic fluid that is pushed out by movement of piston 44 must now pass through filter 130, then metered orice of forward feed valve 65 and check valve 131 since check valves 132, 127 and 170 close the only other paths for escape of uid from cylinder 40. Quill 11 then commences the feed portion of its cycle wherein the rate of movement of quill 11 is determined by the rate of fluid ow through the orifice of forward feed valve 65. This orice is adjustable in size so as to provide for variation in forward feed rate.

As the feed stroke continues, quill 11 carries the prepositioned stop nut 73 (see Fig. l and dotted line position of Fig. 5) into contact with stop abutment 71 on stop tube 70 so as to compress spring 78 and ground the circuit from external contact 82 through conductive ring 78 to the frame of the machine and commence the return stroke of quill 11. Grounding of this connection point is arranged through any suitable circuit to deenergize solenoid valve 53 to permit line 110 to directly communicate with face 118 of air control valve spool 113 through line 116. Spool 113 then moves to the left against stop 50a so as to vent line 51 through exhaust port 120a and supply air pressure to line 52, thereby reversing the direction of movement of quill 11.

The hydraulic uid which is now being driven through line 61 by movement of piston 44 in the direction opposite to the arrow of Fig. 4, finds an unimpeded path through checkvalve 1'27 to the other side of piston 44 in cylinder 40 permitting a rapid return stroke.

It is noted at this point that use of a solenoid valve whose de-energized position causes a return stroke of the quill, provides a device which is failsafe insofar as its electrical circuit is concerned.

As the return stroke progresses, dog 100 contacts operator 102 of valve 101 to vent line 125. However, since the spool of valve 60 does not control the return stroke in this embodiment and the spool has already been moved to the right, the operation of valve 101 has no effect. Continued return of quill 11 and piston 44 brings dog 96 into contact with operator 97 of poppet valve 98 so as to vent line 124, thereby enabling the pressure against face 121 of the spool of hydraulic valve 60 to return the spool to the solid line position of Fig. 4 in which it abuts stop 68. Quill 11 has now been returned to its starting position and the hydraulic system is ready for a forward stroke. Re-energization of solenoid valve 53 will start another cycle of forward movement by venting line 116 through port 48 so as to move spool 113 of air valve 50 to the right against stop 117.

The air-hydraulic control circuit of this invention is readily adaptable to applications which require reverse feeding of quill 1l over a portion of its return cycle rather than the rapid return cycle previously described. Referring again to Figs. 4 and 5, it is seen that check valve 132 and reverse feed valve 140 are provided between lines 61 and 62 of the hydraulic circuit. If check valve 127 is manually locked closed, thereby closing the return path utilized for the quick return stroke previously described, it is seen that the hydraulic fluid then must pass through the metered orifice of reverse feed valve 140 and through check valve 132, thereby controlling the rate at which spindle 44 is allowed to return to its normal or starting position.

If it is desirable toI obtain a value of thrust on quill 11 which is not obtainable through the air circuit supply 49, the modified control system of Fig. 6 permits hydraulic thrust to be added to the available air thrust through the use of a modified hydraulic circuit. The air circuit utilized with this embodiment of the invention is nearly identical with that utilized with Fig. 4 and like numbers refer to like parts of this control system. However, unlike the circuit of Fig. 4, no air is supplied to the main hydraulic valve. Instead, a solenoid operated hydraulic valve 150 is provided to control the hydraulic fluid flow from one side of piston 44 to the other side through lines 151 and 152. Solenoid valve 150 is shown in the cie-energized or quick advance or return position which permits unimpeded flow of the hydraulic fluid from line 152 through line 151 and vice versa. In addition to hydraulic valve 156, there is provided the hydraulic fluid sump or reservoir 153, a forward feed valve 154, a hydraulic pump 155 and a check valve 156. Instead of using the poppet valves and trip dogs of the embodiment of Fig. 4 to control quill movement, a limit switch 160 is provided and is positioned to be operated by cam surface 161 which is adjustably positioned on control rod 95.

In operation, air pressure against piston 33 causes rapid advance of quill 11 until limit switch 160 is closed by cam 161. Closing of limit switch 160 energizes the solenoid of valve 154i through any suitable electrical circuit, thereby closing line 152a and forcing the hydraulic fluid to flow through the controlled orifice of forward feed valve 140 and into sump 153. Check valve 156 prevents direct return of the hydraulic fluid to line 152. However, pump 155 provides the necessary fluid return and also functions to increase the pressure applied by this fiuid to the rear face of piston 44, thereby adding such additional thrust to the controlled forward stroke as is determined by the pressure increase effected by pump 155. Check valve 156 acts as an escape valve in the event that pressure in line 152 exceeds a predetermined limit.

Stop nut 73 cooperates with stop abutment 71 to reverse the direction of quill movement in the same manner as described previously for the preferred embodiment.

From the foregoing description, it is apparent that the power mechanism provided by this invention utilizes component structures which permit an exceptionally compact mechanism which is versatile and easily adaptable to a variety of control systems. In addition, it is seen that the control systems of the instant invention produce a degree of reliability and flexibility hereto unobtainable by prior art systems.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

We claim:

1. An oscillatory power mechanism comprising a shaft, a carriage member coaxial with said shaft, means supporting said shaft for rotation within said carriage member, means supporting said carriage member for axial movement, a rst piston carried by said carriage member and coaxial therewith, a first cylinder carried by the carriage member supporting means and cooperatively arranged with said first piston, a second piston carried by said carriage member and coaxial therewith, a second cylinder carried by the carriage member supporting means and cooperatively arranged with said second piston, means for supplying air under pressure to said first cylinder to effect axial movement of said first piston, carriage member and shaft, a hydraulic fluid in said second cylinder, and means controlling the rate at which movement of said carriage member causes said second piston to force said fiuid out of said second cylinder, thereby to control the rate at which said shaft is moved by air pressure acting upon said first piston.

2. An oscillatory power mechanism comprising a frame having a longitudinal axis, a carriage member supported for movement relative to said frame along said longitudinal axis, a power shaft supported for rotation within said frame, a drive tube rotatably supported by said frame and splined to said shaft to effect rotation of said shaft While permitting relative sliding movement between said shaft and said drive tube, a stop tube supported by said frame disposed intermediate said drive tube and said carriage and coaxial therewith, an abutment on said stop tube adjacent one end thereof. a second abutment carried by said carriage member and disposed relative to the abutment on said stop tube so as to be engageable therewith by relative axial movement therebetween, a first piston supported by said carriage and coaxial with said shaft, a first cylinder carried by said frame and cooperatively arranged with said first piston, a second piston supported by said carriage and arranged coaxially with said power shaft, a second cylinder supported by said frame and cooperatively arranged with said second piston, means for supplying air to said first cylinder to move said first piston, a hydraulic fiuid in said second cylinder, means controlling the rate at which said second piston forces said fluid out of said second cylinder, thereby to control the rate at which said second piston and said shaft are moved by air pressure acting upon said first piston, and means controlling the supply of air to said first piston, said means being operable by engagement of the abutment on said stop tube with the abutment supported by said carriage, thereby to limit the amount of axial movement accorded to said shaft.

3. The oscillatory control mechanism as set forth in claim 2 wherein the stop abutment supported by said carriage is adjustable relative to said abutment on said stop tube along the longitudinal axis of said frame, thereby to permit variable control of the longitudinal movement permitted said shaft.

4. A power mechanism comprising a shaft, means supporting said shaft for axial movement, a first piston coaxial with and operatively connected to said shaft, a first cylinder cooperatively arranged with said first piston, a second piston coaxial with and operatively connected to said shaft, a second cylinder operatively arranged with said piston, means for supplying air under pressure to said first cylinder to effect movement of said first piston, a hydraulic fluid in said second cylinder, means controlling the rate at which movement of said second piston forces said fluid out of said second cylinder, thereby to control the rate at which said second piston and said shaft are moved by air pressure acting upon said first piston, and means for selectively supplying additional hydraulic fluid under pressure to said second cylinder on the other side of said piston, thereby to impart a hydraulic force acting to move said shaft in an axial direction.

5. An oscillatory power mechanism comprising a frame having a longitudinal axis, a carriage member supported for movement relative to said frame along said longitudinal axis, a power shaft supported for rotation within said frame, a drive tube rotatably supported by said frame and splined to said shaft to effect rotation of said shaft while permitting relative sliding movement between said shaft and said drive tube, a stop tube supported by Said frame disposed intermediate said drive tube and said carriage and coaxial therewith, an abutment on said stop tube adjacent one end thereof, a sec ond abutment carried by said carriage member and disposed relative to the abutment on said stop tube so as to be engageable therewith by relative axial movement therebetween, a lirst piston supported by said carriage and coaxial with said shaft, a rst cylinder carried by said frame and cooperatively arranged with said rst piston, a second piston supported by said carriage and arranged coaxially with said power shaft, a second cylinder supported by said frame and cooperatively arranged with said second piston, means for selectively supplying air to either end of said first cylinder to move said first piston, a hydraulic fluid in said second cylinder, means controlling the rate at which said piston forces said uid out of said second cylinder, thereby to control the rate at which said second piston and said shaft are moved by air pressure acting upon said rst piston, and means operable by engagement of the abutment on said stop tube with the abutment supported by said carriage to reverse the supply of air from one end of said rst cylinder to the other, thereby to limit the amount of axial movement permitted said shaft in accordance with the longitudinal positon of said carriage member.

6. An oscillatory power mechanism comprising a shaft, a carriage member coaxial with said shaft, means supporting said shaft for rotation within said carriage member, means supporting said carriage member for axial movement, a rst piston carried by said carriage member and coaxial therewith, a rst cylinder carried by the carriage member supporting means and cooperatively arranged with said iirst piston, a second piston carried by said carriage member and coaxial therewith, a second cylinder carried by the carriage member supporting means and cooperatively arranged with said second piston, means for supplying air to said first cylinder to effect axial movement of said first piston, a hydraulic Huid in said second cylinder, means for controlling the rate of fluid ow out of said second cylinder, and a control member adjustably positioned on said carriage member and arranged to actuate the means controlling the rate of uid ow out of said second cylinder, thereby to control carraige speed as a function of carriage position.

References Cited in the le of this patent UNITED STATES PATENTS 2,655,058 Eschenburg et al. Oct. 13, 1953 2,676,572 Perry et al. Apr. 27, 1954 2,715,389 Johnson Apr. 16, 1955 2,765,808 Tydeman Oct. 9, 1956 2,781,026 Schlatter et al. Feb. 12, 1957 2,857,789 Robinson Oct. 28, 1958 FOREIGN PATENTS 462,136 Canada Dec. 27, 1949

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