US2764365A - Hydraulic drive for winding machine - Google Patents

Description

p 25, 1956 E. DAVIS ET AL HYDRAULIC DRIVE FOR WINDING MACHINE 3 Sheets-Sheet 1 Filed Sept. l3. 1954 INVENTORS MAURICE E.GRANT RICHARD E. DAVIS ATTORNEY 3 Sheets-Sheet Sept. 25, 1956 E. DAVIS ET AL HYDRAULIC DRIVE FOR WINDING MACHINE Filed Sept. 13. 195 1 l mm M Q mm M Q 3 s G. A 3 K m E 2? mm w 3 mm w W m 3 5 mm mm ow e.N VI A 4 1 B J n mm I fi wn w lmn .mnm t2 8 x \\\b 4/ & m m Z on 9. 5 m7, 2. m mm 12?. mos: I .22 mm mp H MM. Q on 8 N 1 E RICHARD E. DAVIS MW ATTORNEY g 0 mp 2. E. l m m. llll 1 nh j Sept. 25, 1956 R. E. DAVIS ET AL 2,764,365

HYDRAULIC DRIVE FOR WINDING MACHINE led Sept. 13, 1954 3 Sheets-Sheet 3 FIG. 4

INVENTORS MAURICE E. GRANT RICHARD E. DAVIS ATTORNEY United States Patent HYDRAULIC DRIVE FOR WINDING MACHINE Richard E. Davis, Summit, Wis., and Maurice E. Grant,

Rockford, 111., assignors to The Oilgear Company, Milwaukee, Wis., a corporation of Wisconsin Application September 13, 1954, Serial No. 455,414

20 Claims. (Cl. 242-75) This invention relates to hydraulic drives for winding machines and more particularly to a winder drive for the type employed to drive a winding shaft upon which a sheet, strip or strand of flexible material is wound into a roll as fast as the material is delivered thereto from another machine or from another part of the machine of which the winding shaft forms a part.

A hydraulic winder drive includes a hydraulic motor which is mechanically connected to the winding shaft, a pump for supplying motive liquid to the motor to enable it to drive the shaft, and means for increasing the torque of the motor as the roll of material increases in diameter.

A winder drive must maintain tension on the material during the winding operation and the tension must be maintained within close limits in order to produce a roll of the desired density and to prevent the material from wrinkling, buckling or breaking or the inner turns of the material from moving axially during the winding of other turns outward therefrom.

The present invention has as an object to provide a winder drive capable of maintaining the correct tension upon flexible material while winding the material into a roll.

Another object is to provide novel means for increasing the torque of the motor as the roll of material on the winding shaft increases in diameter.

Other objects and advantages will be apparent from the following description of the winder drives shown schematically in the accompanying drawings in which the views are as follows:

Fig. 1 is a diagrammatic view illustrating the hydraulic circuit of a preferred embodiment of the invention and showing the relation of the various parts to each other, some of the parts being shown in full, certain parts being broken away to expose other parts and certain parts being shown in section.

Fig. 2 is a view similar to Fig. 1 but illustrating a dilferent embodiment of the invention. v

Fig. 3 is a view showing a'control valve which may be used in place of the control valves shown in Figs. 1 and 2.

Fig. 4 is a view similar to the right hand portion of Fig. 1 and showing a different means for compressing the spring of the control valve, the motor and the pumps being shown on a larger scale than in Fig. 1.

For the purpose of illustration the drive has been shown as being employed to drive the shaft 1 of a winding machine and cause it to wind a strip of paper 2 thereon into a roll 3 as fast as the paper is delivered by the delivery rolls 4 of a calender. Since the winding machine, the calender and the paper do not per se form any part of the present invention, only parts thereof have been indicated in the drawings.

Fig. 1

The drive shown in this figure includes a rotary hydraulic motor 5 which is adapted to drive shaft 1 through a suitable drive 6 and a pump 7 which delivers liquid to motor 5 through a channel 8 and has liquid returned 2,764,365 Patented Sept. 25, 1956 to it through a channel 9 and which is driven in unison with rolls 4 such as by being driven by an electric motor (not shown) having suitable controls.

Pump 7 may be of any type which has a member shiftable to vary its displacement and a control which will cause the pump to discharge liquid at a predetermined maximum rate until pump pressure reaches a predetermined maximum and will then reduce pump displacement until the pump is delivering just enough liquid to maintain that pressure constant.

For the purpose of illustration, the pump has been indicated as being of the rolling piston type disclosed in Patent No. 2,074,068 and as having a pressure responsive control of the type disclosed in Patent No. 2,080,810. Since both the pump and the control are well known and in extensive commercial use, it is deemed sufficient to state herein that pump 7 has its mechanism arranged within a casing 10, that it has its pistons 11 arranged radially in a cylinder barrel 12 which rotates upon a stationary axis, that the outer ends of pistons 11 engage an annular thrust member 13 which is arranged within a displacement varying member or slide block 14 and is rotatably supported thereby, that slide block 14 is shiftable transversely of the axis of cylinder barrel 12 but is restrained by casing 10 from movement in any other direction, and that pump 7 when driven will discharge liquid through channel 8 at a rate proportional to the distance that the axis of members 13 and 14 is offset from the axis of cylinder barrel 12. Pump 7 is supplied with liquid from a reservoir 15 through a channel 16 which connects the intake side of pump 7 to reservoir 15 and has a check valve 17 arranged therein.

Slide block 14 is urged toward maximum displacement position by a constant force, such as by a spring 20, and it is adapted to be moved toward zero displacement position by hydraulic servo-motor shown as comprising a cylinder 21, which is carried by casing 10, and a piston 22 which is fitted in cylinder 21 and engages or is fixed to slide block 14.

Liquid for operating servo-motor 21--22 is supplied thereto under the control of a control valve 23 having its mechanismarranged within a casing 24 which in practice is attacheddirectly to pump casing 10 but which has been shown separate therefrom to simplify the drawing. Casing 24 has formed therein an axial bore 25 which is connected at its lower end to the discharge side of pump 7 by a pressure channel 26, an annular groove or port 27 which is formed in the wall of bore 25 and is connected to cylinder 21 by a channel 28 having a choke 29 arranged therein to limit the rate at which liquid can flow into cylinder 21, and a counterbore 30 which is larger than and concentric with bore 25 and is closed at its upper end by a cover plate 31.

Flow of liquid into and out of cylinder 21 is controlled by a valve member consisting of a valve element 34, which is closely fitted in bore 25 and has at least one notch 35 formed in its lower end, and a piston 36 which is fixed to element 34 and is closely fitted in counterbore 30. Any pressure created by pump 7 will extend through channel 26 into bore 25 and tend to move valve member 34-36 upward against the resistance of a spring 37 arranged between piston 36 and a piston 38 which is closely fitted in counterbore 30 and provides between its upper face and the lower face of cover plate 31 a pressure chamber 39 to which liquid under pressure is supplied as will presently be explained.

The force exerted by spring 37 is initially regulated by an adjusting screw 40 which is threaded through cover plate 31 and engages piston 38 until the force exerted by the liquid in chamber39 exceeds the force with communicate when the valve is closed with an annular groove or port 43 which is formed in the wall of counterbore and is connected to cylinder 21 by a channel 44.

The parts preferably are so constructed that the vertical distance between slots and 42 is exactly equal to the vertical distance between the lower edge of port 27 and the upper edge of port 43. When the pressure created by pump 7 has reached a predetermined value as determined by the resistance of spring 37 or by the pressure in chamber 39, it will have raised valve member 3436 until the bottom of slot 35 is even with the lower edge of port 27 and the bottom of slots 42 are even with the upper edge of port 43 so that there is no flow of liquid either into or out of cylinder 21.

Then a slight increase in pump pressure will cause valve member 3436 to rise and permit liquid to flow from pipe 26 through bore 25, slot 35, port 27 and channel 28 into cylinder 21 and cause piston 22 to shift slide block 14 toward the right to reduce pump displacement until pump 7 is discharging just enough liquid to maintain pump pressure at a predetermined value. Conversely, a slight drop in pump pressure will permit spring 37 or the pressure in chamber 39 to move valve member 3436 downward to partly uncover port 43 so that liquid can escape from cylinder 21 through channel 44, port 43 and counterbore 30 into drain channel 41, thereby permitting spring 20 to move slide block 14 toward the left to increase pump displacement until pump 7 is discharging enough liquid to maintain pump pressure at the predetermined value.

Liquid is supplied to pressure chamber 39 by an auxiliary pump 45, indicated as being a gear pump, which has been shown separate from pump 7 but in practice pump 45 is driven in unison with pump 7 and is arranged within the casing thereof as is customary. Pump 45 draws liquid from reservoir 15 and discharges it into a branched supply channel 46 one branch of which is connected through a choke 47 to a channel 48 having one end thereof connected to chamber 39 and the other end thereof connected to the inlet of a resistance valve 49.

Choke 47 is provided in order that some of the liquid discharged by pump 45 may be used for other purposes.

Liquid discharged into channel 48 will flow to exhaust through resistance valve 49 which enables pump 45 to maintain in channel 48 and in chamber 39 a pressure proportional to the resistance of the spring 50 of valve 49. The resistance of spring 50 is gradually increased in response to roll 3 gradually increasing in diameter as will presently be explained.

In order to prevent damage to the parts in case pump pressure should rise so suddenly that the above described control could not reduce pump displacement fast enough to prevent pump pressure from becoming dangerously high, the drive preferably is provided with an emergency safety valve 54 having its mechanism arranged within a casing 55 which in practice is a part of control valve casing 24 but which has been shown separate therefrom in order to simplify the drawing.

As shown, casing 55 has formed therein an axial bore 56, a larger concentric counterbore 57 arranged at the upper end of bore 56 and closed at its upper end by a cover plate 58, a port 59 arranged at the lower end of bore 56 and provided in its lower wall with an annular valve seat 60 through which when valve 54 is opened liquid may flow from port 59 into an exhaust channel 61 which extends into reservoir 15.

Valve seat 60 is normally engaged by the lower end of a valve member consisting of a valve element 62, which is closely fitted in bore 56, and a piston 63 which is closely fitted in counterbore 57. Valve member 62-63 is urged against valve seat 66 by a spring 64 arranged between piston 63 and cover plate 58. Port 59 is con nected to the lower end of bore 25 by a channel 65, that part of counterbore 57 below piston 63 is connected to port 27 by a channel 66 having a choke 67 arranged therein, and that part of counterbore 57 above piston 63 is connected to exhaust by a drain channel 68.

The arrangement is such that, when the pressure created by pump 7 becomes 'high enough to raise control valve element 34 until liquid can flow from channel 26 through bore 25, port 27 and channel 28 to cylinder 21 and cause piston 22. to move slide block 14 toward the right to thereby effect a reduction on the displacement of pump 7 as explained above, pressure will extend through channel 66 into the lower end of counterbore 57 and, if the displacement of pump 7 is not reduced fast enough to prevent pump pressure from rising still higher, the pressure in the lower end of counterbore 57 will raise valve member 6263 and thereby permit enough liquid to flow from channel 26 through bore 25, channel and port 59 into exhaust channel 61 to prevent any further increase in pump pressure.

In order to gradually-increase the pressure created by pump 7 as roll of paper 2 increases in diameter to thereby enable motor 5 to maintain a constant or gradually varying tension on paper 2 as it is wound into a roll, the drive is provided with a hydraulic differential comprising a small variable displacement hydraulic tachometer or pilot pump 7b, which is driven at a speed proportional to the rotary speed of roll 3 such as by being driven from shaft 1 through a suitable drive 71, and a small tachometer or pilot pump 72 which has a constant or preset displacement and is driven at a speed proportional to the linear speed of paper 2 such as by being driven from roll 4 through a suitable drive 73.

Pilot pump has been indicated in the drawing as being of the same general type as pump 7 so that detailed illustration and description is unnecessary. it is deemed. sufiicient to state that pump 74; has its mechanism arranged within a casing 7 4, that it includes a displacement varying memberor slide block 75 which is slidably fitted in casing 74 and corresponds to the slide block 14 of pump 7, and that it includes pistons, a cylinder barrel and a thrust member (not shown) which correspond with pistons 11, cylinder barrel 12 and thrust member 13 of pump 7 and are arranged within slide block 75. The control for pump 70 differs from the control for pump 7 in that slide block 75 is urged toward a minimum displacement position by a spring 76 and is adapted to be moved toward maximum displacement position by a servo-motor comprising a cylinder 77, which is carried by casing 74, and a piston 78 which is fitted in cylinder '77 and engages or is connected to slide block '75.

Pump 78 has its outlet connected to the inlet of pump 72 by a channel '79 and its inlet connected to the outlet of pump '72 by a channel 30 which is also connected to cylinder 77 by a branch 81 of channel 34 Channels 75 and form with pumps "ill and 72 a closed hydraulic circuit so that all the liquid discharged by pump enters or attempts to enter pump 70. The pilot pump circuit is kept filled with liquid by connecting a branch of supply channel 46 to channel 79. In practice, two oppositely opening relief valves are connected between channels 79 and 80 to prevent the pressure in the pilot circuit from exceeding a predetermined value but since that is common practice the relief valves have be omitted from the drawings to allow more room for other parts.

The displacements of pumps 70 and 72 are initially so adjusted that, when paper 2 first starts to accumulate on shaft 1, the volume of liquid discharged by pump 72 will be just sufficient to supercharge pump 70 at a low pressure. Then as the speed of shaft 1 decreases due to roll 3 increasing in diameter as previously explained, pump 70 will be driven at a progressively decreasing speed but pump 72 will continue tobe driven at a constant speed and will discharge liquid in excess of the liquid required to supercharge pump 70. The excess liquid will flow through branch channel 81 into cylinder 77 and cause piston 78 to move slide block 75 toward the right to increase the displacement of pump 70 in proportion to the decrease in its speed and thereby enable pump 78 to consume all of the liquid delivered thereto by pump 72.

Movement of slide block 75 toward the right is proportional to the increase in the diameter of roll 3 and that movement is utilized to correspondingly increase the pressure in chamber 39. As shown, a push rod 82 is movable with slide block 75 and is pivotally connected to a lever 83, which is pivoted at one of its ends upon a stationary support 84, and lever 83 is pivotally connected to one end of an adjusting member 85 which has its other end in engagement with resistance valve spring 50.

The arrangement is such that, when slide block 75 moves gradually toward the right in response to an increase in the diameter of roll 3, push rod 82 will swing lever 83 upon support 84 and lever 83 will cause member 85 to gradually compress spring 50 to increase the resistance thereof and thereby enable auxiliary pump 45 to maintain a gradually increasing pressure in chamber 39. Push rod 82, lever 83 and adjusting member 35 thus constitute thrust transmitting means for adjusting the resistance of spring 50 in response to movement of slide block 75.

Means should be provided to adjust the initial compression of spring 58 and to vary the ratio between further compression of spring 50 and the movement of slide block 75. The initial compression of spring 50 may be adjusted by providing between it and member 85 suitable shims which may be varied as to number or thickness or by making member 85 extensible such as by making it in two sections and connecting the two sections by means of a turnbuckle. The ratio between the movement of slide block 75 and the resultant compression of spring 50 may be made variable such as by pivotally connecting member 85 to a block which is slidable in a slot formed in lever 83 and moving the block along the slot by means of a screw. Since such means are old and well known, they have not been illustrated and adjustment of spring 58 has been indicated by showing member 85 connected to lever 83 by means of a pin 86 which may be inserted in any one of a plurality of holes 87 formed in lever 83.

OPERATION Assuming that the end of strip of paper 2 has been fastened to a suitable core fixed on winding shaft 1, that pilot pumps 76 and 72 have been so adjusted that pump '72 will discharge liquid at a rate just suflicient to supercharge pump 70 when the drive is started, and that the control for pump 7 has been so adjusted that pump 7 will create just enough pressure to enable motor 5 to exert just enough torque to exert the proper tension on paper 2 when the drive is started, the drive will operate as follows:

All slack in the paper between shaft 1 and roll 4 is taken up either manually or by inching the motor which drives pump 7. Then pump 7 may be started but, until rolls 4 are started, it cannot deliver liquid to motor 5 which will cause pump pressure to rise and enable the pump control to reduce the displacement of pump 7 in the previously described manner until pump 7 is discharging just enough liquid to maintain a pressure which will enable motor 5 to exert the correct tension upon paper 2.

I Then when rolls 4 start to deliver paper to shaft 1, pumppressure will drop slightly momentarily and permit the pump control to increase the displacement of pump 7 in the previously described manner until pump 7 is discharging liquid at a rate and at a pressure which will enable motor 5 to wind paper 2 into a roll 3 as fast as it is delivered thereto by rolls 4 and to maintain the desired tension on paper 2.

.As roll 3 increasesin diameter, the rotary speed ot shaft 1 will gradually decrease and decelerate motor 5 which will require less liquid than is being currently discharged by pump 7 and the liquid discharged by pump 7 in excess of the liquid required by motor 5 will flow through control valve 23 to cylinder 21 and cause piston 22 to gradually decrease the displacement of pump 7 until it is discharging just enough liquid to drive motor 5.

The gradual increase in the diameter of roll 3 requires that motor 5 exert a gradually increasing torque in order to maintain the desired tension upon paper 2. However, the'speed of pilot pump 70 will decrease at a rate proportional to the rate at which the speed of shaft 1 decreases so that all of the liquid currently discharged by pilot-pump 72 cannot enter pump 70 and the excess liquid discharged by pump 72 Will enter cylinder 77 and cause piston 78 to move slide block gradually toward the right to increase the displacement of pump 70.

Movement of slide block 75 toward the right effects a gradual increase in the resistance of valve 49 which enables auxiliary pump 45 to gradually increase the pressure in chamber 39 of control valve 23 so that pump 7 has-to create a gradually increasing pressure which enables motor 5 to maintain the desired tension upon paper 2 as roll 3 increases in diameter.

If the tension on paper 2 should be maintained constant regardless of the diameter of roll 3, adjusting member is connectedto lever 83 in such a position that resistance valve spring 51) is compressed at a rate proportional to the rate at which roll 3 increases in diameter. If it is desired to increase or decrease the tension on paper 2 as roll 3 increases in diameter, the connection between member 85 and lever 83 may be moved along lever 83 in one direction or the other to increase or decrease the rate at which spring 50 is compressed.

Fig. 2

The drive shown in this figure differs from the drive shown in Fig. 1 in that the rate of delivery of motive liquid to the driving motor is carried by bypassing a part of the liquid discharged by the main pump instead of by decreasing the displacement of the main pump.

Since the two drives are otherwise the same, only a brief description of the drive shown in Fig. 2 is deemed necessary because like parts have been indicated by like reference numerals and corresponding parts have been indicated by corresponding reference numerals with the exponent a added to the reference numerals applied to Fig.2.

As shown, the winding shaft 1 is driven by a motor 5 through a drive 6 and winds paper 2 into a roll 3 as fast as it is delivered by rolls 4. Liquid for energizing motor 5 is supplied thereto by a constant displacement pump 7 which has its outlet connected to the inlet of motor 5 by a channel 8 and its inlet connected to the outlet of motor 5 by a channel 9.

The outlet of pump 7 is also connected by a channel 26 to the inlet of a control valve 23* which is the same as valve 23 except that port 43 and the connections for channels 44, 65 and 66 are omittedand port 27 is connected to a channel 28 which discharges into reservoir 15. Control valve 23 operates in the same manner as control valve 23 and the pressure in its chamber 39 is regulated in the same way and by the same means as in the drive shown in Fig. 1.

Pump 7 has suflicient volumetric capacity to enable it to discharge liquid at a rate slightly in excess of the rate required by motor to enable it to drive shaft 1 at the correct speed when paper 2 first starts to accumulate upon shaft 1.

The arrangement is such that, when paper 2 has been fastened to shaft 1 and rolls 4 and pump 7* are started, the liquid discharged by pump 7 in excess of the liquid required by motor 5 will flow through channel 26, move element 34 of valve 23 until the bottom of notch 35 is slightly within port 27 as shown, and then the excess liquid will flow through valve 23 and channel 28 into reservoir and the resistance of valve 23 to the flow of liquid therethrough will cause pump 7 a to create just enough pressure to enable motor 5 to drive shaft 1 and to apply the correct tension to paper 2.

As paper 2 accumulates on shaft 1, the rotary speeds of shaft 1 and motor 5 will gradually decrease due to roll 3 increasing in diameter. As motor 5 gradually decelerates, less liquid is required to drive it which will cause the flow of liquid through valve 23 to gradually increase.

The decrease in the speeds of shaft 1 and motor 5 will also cause the pressure in chamber 39 to gradually increase in the same manner as in the drive shown in Fig. l and thereby cause the pressure created by pump 7 to gradually increase and enable motor 5 to exert a gradually increasing torque as roll 3 increases in diameter.

Fig. 3

Since the control valve 23 shown in this figure is nearly the same as the control valve 23 shown in Fig. 1, like parts have been indicated by like reference numerals and corresponding parts have been indicated by corresponding reference numerals with the exponent b" added to the numerals applied to Fig. 3 so that only a brief description of valve 23 is necessary.

Valve 23 differs primarily from valve 23 in that screw 40 is omitted therefrom, piston 38 is replaced by an imperforate piston 38 and spring 37 is replaced by a rod 37 The two valves function in the same manner but the closing force exerted upon valve member 34-36 of valve 23 may be determined by the adjustment of spring 37 until paper accumulates upon shaft 1 and then be determined by the pressure in chamber 39 while in valve 23 the closing force is determined at all times by the pressure in chamber 39.

However, if a choke 47 is inserted between chamber 39 and the auxiliary pump as shown in Figs. 1 and 2, a control valve having a spring is preferred because the spring enables the valve to open or close instantly While without the spring movement of valve member 34--36 causes liquid to flow through choke 47 which slows down the action of valve member 3436.

Fig. 4

The drive shown in this figure is substantially the same as the drive shown in Fig. 1 except that the resistance of the control valve spring is varied mechanically instead of hydraulically. Therefore, only a portion of the drive has been shown in order to show certain parts on a larger scale and of the parts shown like parts have been indicated by like reference numerals and corresponding parts have been indicated by corresponding reference numerals with the exponent c added to the reference numerals applied to Fig. 4 so that a detailed description of the drive is unnecessary.

The drive includes a motor 5 which drives winding shaft 1 through a suitable drive 6, a pump 7 which is connected to motor 5 by channels 8 and 9, a pilot pump 70 which is driven from shaft 1 through a suitable drive 71 and is connected by channels 79 and 80 to the pilot pump 72 (not shown) which is driven from delivery rolls 4.

The displacement of pump 7 is controlled by a control valve 23 which is connected to the servo-motor cylinder 21 of pump 7 and to a safety valve 54 in the same manner and by the same means as in the drive shown in Fig. 1. Valve 23 differs from valve 23 in that cover plate 31 and piston 38 are replaced by a piston 38 which is slidable in the upper part of counterbore 3t) and adapted to be moved mechanically in response to movement of the slideblock 75 of pilot pump '70. Since valve 23 is otherwise the same as valve 23, like parts have been indicated by like reference numerals so that further description thereof is unnecessary.

As shown, piston 38 has an adjusting screw 40 threaded therein and engaged by one arm of a bell crank lever 30 which is pivoted upon a stationary pin 91 and has a sleeve 92 threaded upon its other arm and locked in an adjusted position by a lock nut 93. Sleeve 92 has a coupling 94 journaled thereon and pivotally connected to the push rod 82 of pilot pump 70. The arrangement is such that the ratio between the movement of slide block 75 and the movement of piston 325 may be varied by loosening lock 3 and turning sleeve 92.

Adjusting screw 40 may be turned until spring 37 offers just enough resistance to hold the bottom of notch 35 even with the bottom of port 27 when pump 7 is creating just enough pressure to enable motor 5 to exert just enough torque to maintain the correct tension on strip 2 when the material first starts to accumulate on shaft 1.

Then as roll of material 3 increases in diameter and causes slide block 75 to gradually move toward the right as previously explained, push rod 82 will swing lever upon pin 91 and lever 90 will gradually compress spring 37 to thereby cause pump 7 to create a gradually increasing pressure with the resultant gradual increase in the torque exerted by motor 5.

The invention herein set forth is susceptible of other modifications and adaptations without departing from the scope of the invention which is hereby claimed as follows:

1. In a hydraulic drive for rotating a winding shaft to which flexible material is delivered by a machine and on which said material is wound into a roll whereby the rotary speed of said shaft decreases relatively to the linear speed of said material as said roll of material increases in diameter, the combination of a hydraulic motor connected to said shaft to rotate the same, a main pump connected to said motor for supplying motive liquid thereto to enable said motor to drive said shaft, and means for controlling the rate and pressure at which said liquid is delivered to said motor including a control valve casing having a bore and an outlet port and a counterbore communicating with said bore, a pressure channel connecting said bore to the outlet of said main pump, a valve element fitted in said bore to control communication between said pressure channel and said port and having its end subjected to the pressure created by said pump, a piston fitted in said counterbore and forming therewith a pressure chamber, means for transmitting force from said piston to said valve element, an auxiliary pump connected to said pressure chamber, a resistance valve connected to said auxiliary pump to permit it to discharge liquid therethrough and having a spring to resist said discharge of liquid and thereby enable said auxiliary pump to create in said chamber a pressure which causes said piston to urge said valve element toward its closed position with a force proportional to the resistance of said spring, and means responsive to the speed of said shaft decreasing for increasing the resistance of said resistance valve spring.

2. A hydraulic drive according to claim 1 in which said speed responsive means includes a first pilot pump driven at a speed proportional to the linear speed of said material, a second pilot pump driven at a speed proportional to the rotary speed of said shaft so that the speed of said second pilot pump decreases as the roll of material on said shaft increases in diameter, said second pilot pump having a displacement varying member continuously urged toward a minimum displacement position and a servomotor for moving said member toward a maximum displacement position, a first fluid channel connecting the outlet of said second pilot pump to the inlet of said first pilot pump, a second fluid channel connecting the outlet of said first pilot pump to the inlet of said second pilot pump, a third fluid channel connecting said second channel to said servomotor to permit liquid to flow to said servomotor and enable it to move said displacement varying member toward its maximum displacement position in response to the speed of said second pilot pump decreasing relatively to the speed of said first pilot pump, and a connection between said member and said resistance valve spring to enable said member during movement thereof to increase the resistance of said spring.

3. A hydraulic drive according to claim 2 in which said connection includes a lever having one end thereof pivotally held in a stationary position, thrust transmitting means movable with said displacement Varying member and having a pivotal connection with said lever at a point intermediate the ends thereof, a compressor engaging said resistance valve spring and having a pivotal connection with said lever at a point spaced from said first mentioned point, and means for varying the distance between said pivotal connections.

4. In a hydraulic drive for rotating a Winding shaft to which flexible material is delivered by a machine and on which said material is wound into a roll whereby the rotary speed of said shaft decreases relatively to the linear speed of said material as said roll of material increases in diameter, the combination of a hydraulic motor connected to said shaft to rotate the same, a main pump connected to said motor for supplying motive liquid thereto to enable said motor to drive said shaft, and means for controlling the rate and pressure at which said liquid is delivered to said motor including a control valve casing having a bore and an outlet port and a counterbore communicating with said bore, a pressure channel connecting said bore to the outlet of said main pump, a valve member having one part thereof fitted in said bore to control communication between said channel and said port and another part thereof arranged in said counterbore, said valve member being urged toward open position by the pressure in said channel, a piston fitted in said counterbore and forming therewith a pressure chamber, a spring arranged between said valve member and said piston for urging said valve member toward closed position with a force proportional to the resistance of said spring, an auxiliary pump connected to said pressure chamber, a resistance valve connected to said auxiliary pump to permit it to discharge liquid therethrough and having a spring to resist said discharge of liquid and thereby enable said auxiliary pump to create in said chamber a pressure which enables said piston to maintain the resistance of said first mentioned spring proportional to the resistance of said resistance valve spring, and means responsive to the speed of said shaft decreasing for increasing the resistance of said resistance valve spring.

5. A hydraulic drive according to claim 4 in which said speed responsive means includes a first pilot pump driven at a speed proportional to the linear speed of said material, a second pilot pump driven at a speed proportional to the rotary speed of said shaft so that the speed of said second pilot pump decreases as the roll of material on said shaft increases in diameter,

said second pilot pump having a displacement varying member continuously urged toward a minimum displacement position and a servo-motor for moving said member toward a maximum displacement position, a

first fluid channel connecting the outlet of said second pilot pump to the inlet of said first pilot pump, a second fluid channel connecting the outlet of said first pilot pump to the inlet of said second pilot pump, a third fluid channel connecting said second channel to said servo-motor to permit liquid to flow to said servo-motor and enable it to move said displacement varying member toward its maximum displacement position in response 10 to the speed of said second pilot pump decreasing relatively to the speed of said first pilot pump, and a connection between said member and said resistance valve spring to enable said member during movement thereof to increase the resistance of said spring.

6. A hydraulic drive according to claim 5 in which said connection includes a lever having one end thereof pivotally held in a stationary position, thrust transmitting means movable with said displacement varying member and having a pivotal connection with said lever at a point intermediate the ends thereof, a compressor engaging said resistance valve spring and having a pivotal con nection with said lever at a point spaced from said first mentioned point, and means for varying the distance be- 7 tween said pivotal connections.

7. In a hydraulic drive for rotating a winding shaft to which flexible material is delivered by a machine and on which said material is wound into a roll whereby the rotary speed of said shaft decreases relatively to the linear speed of said material as said roll of material increases in diameter, the combination of a hydraulic motor connected to said shaft to rotate the same, a variable displacement main pump connected to said motor for supplying motive liquid thereto to enable said motor to drive said shaft, said pump having a displacement varying element continuously urged toward a maximum displacement position and a servo-motor for moving said element toward a minimum displacement position, and means for controlling the rate and pressure at which said liquid is delivered to said motor including a control valve casing having a bore and an outlet port and a counterbore communicating with said bore, a pressure channel connecting said bore to the outlet of said main pump, a channel connecting said port to said servo-motor, a valve member having one part thereof fitted in said bore to control communication between said channel and said port and another part thereof arranged in said counterbore, said valve member being urged toward open position by the pressure in said channel, a piston fitted in said counterbore and forming therewith a pressure chamber, means for transmitting force from said piston to said valve element, an auxiliary pump connected to said pressure chamber, a resistance valve connected to said auxiliary pump to permit it to discharge liquid therethrough and having a spring to resist said discharge of liquid and thereby enable said auxiliary pump to create in said chamber a pressure which causes said piston to urge said valve ele ment toward its closed position with a force proportional to the resistance of said spring, said valve member being adapted to open said port to said pressure channel and per mit liquid to flow from said main pump to said servo-motor and cause it to move said displacement varying element in a direction to reduce the displacement'of said main pump in response to the force exerted upon said valve member by main pump pressure exceeding the force exerted thereon by the pressure in said chamber, and means responsive to the speed of said shaft decreasing for increasing the resistance of said resistance valve spring.

8. A hydraulic drive according to claim 7 in which said speed responsive means includes a first pilot pump driven at a speed proportional to the linear speed of said material, a second pilot pump driven at a speed proportional to the rotary speed of said shaft so that the speed of said second pilot pump decreases as the roll of material on said shaft increases in diameter, said second pilot pump having a displacement varying member continuously urged toward a minimum displacement position and a servo-motor for moving said member toward a maximum displacement position, a first fluid channel connecting the outlet of said second pilot pump to the inlet of said first pilot pump, a second fluid channel connecting the outlet of said first pilot pump to the inlet of said second pilot pump, a third fluid channel connecting said second channel to said servo-motor to permit liquid to flow to said servo-motor and enable it to move said displacement 1 1 varying member toward its maximum displacement position in response to the speed of said second pilot pump decreasing relatively to the speed of said first pilot pump, and a connection between said member and said resistance valve spring to enable said member during movement thereof to increase the resistance of said sprin 9. A hydraulic drive according to claim 8 in which said connection includes a lever having one end thereof pivotally held in a stationary position, thrust transmitting means movable with said displacement varying member and having a pivotal connection with said lever at a point intermediate the ends thereof, a compressor engaging said resistance valve spring and having a pivotal connection with said lever at a point spaced from said first mentioned point, and means for varying the distance between said pivotal connections.

it). In a hydraulic drive for rotating a winding shaft to which flexible material is delivered by a machine and on which said material is wound into a roll whereby the rotary speed of said shaft decreases relatively to the linear speed of said material as said roll of material increases in diameter, the combination of a hydraulic motor connected to said shaft to rotate the same, a variable displacement main pump connected to said motor for supplying motive liquid thereto to enable said motor to drive said shaft, said pump having a displacement varying element continuously urged toward a maximum displacement position and a servo-motor for moving said element toward a minimum displacement position, and means for controlling the rate and pressure at which said liquid is delivered to said motor including a control valve casing having a bore and an outlet port and a counterbore communicating with said bore, a pressure channel connecting said bore to the outlet of said main pump, a channel COnnecting said port to said servo-motor, a valve member havin' one part thereof fitted in said bore to control communication between said channel and said port and another part thereof arranged in said counterbore, said valve member being urged toward open position by the pressure in said channel, a piston fitted in said counter bore and forming therewith a pressure chamber, a spring arranged between said valve member and said piston for urging said valve member toward closed position with a force proportional to the resistance of said spring, an auxiliary pump connected to said pressure chamber, a resistance valve connected to said auxiliary pump to permit it to discharge liquid therethrough and having a Spr nfl to resist said discharge of liquid and thereby enable said auxiliary pump to create in said chamber a pressure which enables said piston to maintain the resistance of said first mentioned spring proportional to the resistance of said resistance valve spring, said valve member being adapted to open said port to said pressure channel and permit liquid to flow from said main pump to said servomotor and cause it to move said displacement varying element in a direction to reduce the displacement of said main pump in response to the force exerted upon said valve member by main pump pressure exceeding the force exerted thereon by the pressure in said chamber, and means responsive to the speed of said shaft decreasing for increasing the resistance of said resistance valve spring.

ll. A hydraulic drive according to claim 10 in which said speed responsive means includes a first pilot pump driven at a speed proportional to the linear speed of sai material, a second pilot pump driven at a speed proportional to the rotary speed of said shaft so that the speed of said second pflot pump decreases as the roll of material on said shaft increases in diameter, said second pilot pump having a displacement varying member continuously urged toward a minimum displacement position and servo-motor for moving said member toward a maximum displacement position, a first fluid channel conthe outlet of said first pilot pump to the inlet of said second pilot pump, a third fiuid channel connecting said second channel to said servo-motor to permit liquid to flow to said servo-motor and enable it to move said displacement varying member toward its maximum displacement position in response to the speed of said second pilot pump decreasing relatively to the speed of said first pilot pump, and a connection between said member and said resistance valve spring to enable said member during movement thereof to increase the resistance of said spring.

12. A hydraulic drive according to claim 11 in which said connection includes a lever having one end thereof pivotally held in a stationary position, thrust transmitting means movable with said displacement varying member and having a pivotal connection with said lever at a point intermediate the ends thereof, a compressor engaging said resistance valve spring and having a pivotal connection with said lever at a point spaced from said first mentioned point, and means for varying the distance between said pivotal connections.

13. In a hydraulic drive for rotating a Winding shaft to which flexible material is delivered by a machine and on which said material is wound into a roll whereby the rotary speed of said shaft decreases relatively to the linear speed of said material as said roll of material increases in diameter, the combination of a hydraulic motor connected to said shaft to rotate the same, a constant displacement main pump connected to said motor for supplying motive liquid thereto to enable said motor to drive said shaft, and means for controlling the rate and pressure at which said liquid is delivered to said motor including a vcontrol valve casing having a bore and an outlet port and a counterbore communicating with said here, a pressure channel connecting said bore to the outlet of said main pump, a channel connecting said port to exhaust, a valve element fitted in said bore to control communication between said pressure channel and said port and having its end subjected to the pressure created by said pump, a piston fitted in said counterbore and forming therewith a pressure chamber, means for transmitting force from said piston to said valve element, an auxiliary pump connected to said pressure chamber, a resistance valve connected to said auxiliary pump to permit it to discharge liquid therethrough and having a spring to resist said discharge of liquid and thereby enable said auxiliary pump to create in said chamber a pressure which causes said piston to urge said valve element toward its closed position with a force proportional to the resistance of. said spring, said valve element being urged toward open position by the pressure created by said main pump and adapted to open said port to said pressure passage and permit a part of the liquid discharged by said main pump to escape to exhaust in response to the opening force exerted on said element by main pump pressure exceeding the closing force exerted on said element by the pressure in said chamber, and means responsive to the speed of said shaft decreasing for increasing the resistance of said resistance valve spring.

14. A hydraulic drive according to claim 13 in which said speed responsive means includes a first pilot pump driven at a speed proportional to the linear speed of said material, a second pilot pump driven at a speed proportional to the rotary speed of said shaft so that the speed of said second pilot pump decreases as the roll of material on said shaft increases in diameter, said second pilot pump having a displacement varying member continuously urged toward a minimum displacement position and a servo-motor for moving said member toward a maximum displacement position, a first fluid channel connecting the outlet of said second pilot pump to the inlet of said first pilot pump, a second fluid channel connecting the outlet of said first pilot pump to the inlet of said second pilot pump, a third fluid channel connecting said second channel to said servo-motor to permaze to which flexible material is delivered by a machine and 4 on which said material is wound into a roll whereby the rotary speed of said shaft decreases relatively to the linear speed of said material as said roll of material increases in diameter, the combination of a hydraulic motor connected to said shaft to rotate the same, a constant displacement main pump connected to said motor for supplying motive liquid thereto to enable said motor to drive said shaft, and means for controlling the rate and pressure at which said liquid is delivered to said motor including a control valve casing having a bore and an outlet port and a counterbore communicating with said bore, a pressure channel connecting said bore to the outlet of said main pump, a channel connecting said port to exhaust, a valve member having one part thereof fitted in said bore to control communication between said channel and said port and another part thereof arranged in said counterbore, said valve member being urged toward open position by the perssure in said channel, a piston fitted in said counterbore and forming therewith a pressure chamber, a spring arranged between said valve member and said piston for urging said valve member toward closed position with a force proportional to the resistance of said spring, an auxiliary pump connected to said pressure chamber, a resistance valve connected to said auxiliary pump to permit it to discharge liquid therethrough and having a spring to resist said discharge of liquid and thereby enable said auxiliary pump to create in said chamber a. pressure which enables said piston to maintain the resistance of said first mentioned spring proportional to the resistance of said resistance valve spring, said valve member being urged toward open position by the pressure created by said main pump and adapted to open said port to said pressure passage and permit a part of the liquid discharged by said main pump to escape to exhaust in response to the opening force exerted on said element by main pump pressure exceeding the closing force exerted on said element by the pressure in said chamber, and means responsive to the speed of said shaft decreasing for increasing the resistance of said resistance valve spring.

'16. A hydraulic drive according to claim '15 in which said speed responsive means includes a tfirst pilot pump driven at a speed proportional to the linear speed of said material, a second pilot pump driven at a speed proportional to the rotary speed of said shaft so that the speed of said second pilot pump decreases as the roll of material'on said shaft increases in diameter, said second pilot pump having a displacement varying member continuously urged toward a minimum displacement position and a servo-motor for moving said member toward a maximum displacement position, a first fluid channel connecting the outlet of said second pilot pump to the in- :let of said first pilot pump, a second fluid channel connecting the outlet of said first pilot pump to the inlet of said second pilot pump, a third fluid channel connecti-ng said second channel to said servo-motor to permit liquid to flow to said servo-motor and enable it to move said displacement varying member toward its maximum displacement position in response to the speed of said second pilot pump decreasing relatively to the speed of said first pilot pump, and a connection between said member and said resistance valve spring to enable said member during movement thereof to increase the resistance of said spring. I

17. In a hydraulic drive for rotating a winding shaft 14 to which flexible material is delivered by a machine and on which said material is wound into a roll whereby the rotary speed of said shaft decreases relatively to the linear speed of said material as said roll of material increases in diameter, the combination of a hydraulic motor connected to said shaft to rotate the same, a main pump connected to said motor for supplying motive liquid thereto to enable said motor to drive said shaft, and means for controlling the rate and pressure at which said liquid is delivered to said motor including a control valve casing having a bore and an outlet port and a counterbore communicating with said bore, a pressure channel connecting said bore to the outlet of said main pump, a :valve element Lfitted in said bore to control communication between said pressure channel and said port and having its end subjected to the pressure created by said pump, .a piston fitted in said counterbore, a spring engaging said piston and urging said valve element toward closed position, a first pilot pump driven at a speed proportional to the linear speed of said material, a second pilot pump driven at a speed proportional to the rotary speed of said shaft so that the speed of said second pilot pump decreases as the roll of material on said shaft increases in diameter, said second pilot pump having a displacement varying member continuously urged toward a minimum displacement position and a servo-motor for moving said member toward a maximum displacement position, a first fluid channel connecting the outlet of said second pilot pump to the inlet of said first pilot pump, a second fluid channel connecting the outlet of said first pilot pump to the inlet of said second pilot pump, a third fluid channel connecting said second channel to said servo-motor to permit liquid to flow to said servo-motor and enable it to move said displacement varying member toward its maximum displacement position in response to the speed of said second pilot pump decreasing relatively to the speed of said first pilot pump, and means responsive to movement of said displacement varying member toward its maximum displacement position for causing said piston to increase the resistance of said spring.

18. A hydraulic drive according to claim 17 in which said last mentioned means is a mechanical linkage for transmitting motion from said member to said piston and having an adjustment for varying the ratio between the movement of said member and the resultant movement of said piston.

19. In a hydraulic drive for rotating a winding shaft to which flexible material is delivered by a machine and on which said material is wound into a roll whereby the rotary speed of said shaft decreases relatively to the linear speed of said material as said roll of material increases in diameter, the combination of a hydraulic motor connected to said shaft to rotate the same, a variable displacement main pump connected to said motor for supplying motive liquid thereto to enable said motor to drive said shaft, said pump having a displacement varying element continuously urged toward a maximum displacement position and hydraulic means for moving said element toward a minimum displacement position, and means for controlling the rate and pressure at which said liquid is delivered to said motor including a control valve casing having a bore and an outlet port and a counterbore communicating with said bore, fluid channels connecting said port and said counterbore to said hydraulic means, a pressure channel connecting the end of said bore to the outlet of said main pump, a valve element fitted in said bore and in said counterbore to control the flow of liquid to and from said hydraulic means and having its end subjected to the pressure created by said pump, a piston fitted in said counterbore, a spring engaging said piston and urging said valve element toward closed position, a first pilot pump driven at a speed proportional to the linear speed of said material, a second pilot pump driven at a speed proportional to the rotary speed of said shaft so that the speed of said second pilot pump decreases as the 15 roll of material on said shaft increases in diameter, said second pilot pump having a displacement varying member continuously urged toward a minimum displacement position and a servo-motor for moving said member toward a maximum displacement position, a first fluid channel connecting the outlet of said second pilot pump to the inlet of said first pilot pump, a second fluid channel connecting the outlet of said first pilot pump to the inlet of said second pilot pump, a third fiuid channel connecting said second channel to said servo-motor to permit liquid to flow to said servo-motor and enable it to move said displacement varying member toward its maximum displacement position in response to the speed of said second pilot pump decreasing relatively to the speed of said first pilot pump, and means responsive to movement of said 15 2,573,938

1 5 displacement varying member toward its maximum displacement position for causing said piston to increase the resistance of said spring.

20. A hydraulic drive according to claim 19 in which said last mentioned means is a mechanical linkage for transmitting motion from said member to said piston and having an adjustment for varying the ratio between the movement of said member and the resultant movement of said piston.

References Cited in the file of this patent UNITED STATES PATENTS Tyler July 4, 1939 Tyler et al. Nov. 6, 1951

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