US2320727A - Hydraulic speed control apparatus - Google Patents

Description

June 1, 1943- K; R. HERMAN r:a1-A1. 2,320,727

HYDRAULIC SPEED CONTROL- APPARATUS Filed Jan. 22, 1940 Patented- June 1, 1943 HYDRAULIC SPEED ooN'raoL APPARATUS Kenneth R.- Herman and James Robinson, De-

troit, Mich., assignors to Vickers, Incorporated, Detroit, Mich., a corporation o2 Michigan Application January 22, 1940, Serial No. 315,000

i 2 claims. (ci. Ixo-9i) This invention relatesl to a hydraulic speed control apparatus.

This invention has particularly to do with that -type of apparatus in which two or more rotary elements are to be controlled as to speed, the

operation-of th rotary elements being such that a certain relationship between the speeds of the two elements is necessary. For example, on machines for winding continuous material such as thread or paper, it is necessary to have a nume y ber of rollers, each of which will be rotated at results in either breakage of the `continuous material or. a considerable slackening as it is being This invention is closely related to a copending application, Serial No. 175,075, iiled Novemwound. In previous hydraulic circuit-s adapted to control this type of winding machine, `it has f been customary to direct oil from one 'roller actuating motor into the next and so on so that theoretically there is a constant volume of oil passing through the motors and there will be -a constant speed. It was expected, of course, that,

there would be an equal dropin pressure across each motor, if ofv equal size, and this drop was compensated for 'in the original setting of the motors. Experience has` proved, however, that this type of device operated successfully only when new since as the wear on each motor increased, there would be a greater slippage and consequently, the motors would get out of synchronism. The drawback is that slippage errors are cumulative unless all motors have identical slip characteristics.

It is an obiect of the present invention to provide a hydraulic control in which the individual power shaft of each roller used in a winding machine, for example, will be rotated ata constant speed. It is a further object to provide a control device for a plurality of power motors which may be utilized to control 'the speed of each motor individually and to control simultaneously-the speed of the motors sq that a deilnite ratio or proportion may be maintained in the speeds of' the motors.

Other objectsf and features of the invention having to do with details of construction and operation will' be brought out in the following description and claims.

Inthe drawing:

Fig. 1 is a view of a hydraulic circuit which, for the most part, is presented diagrammatically for illustrating the features of the invention.

Fig. 2 is a section taken on the lines 2-2 of Fig. 1, showing the cross section of the speed control unit.

I Fig. 3 is a perspective view of a throttle bar which "is intended to be used for simultaneous control for the plurality of motors.

cylinders 28, 28 and 30, and each piston has a ber 17, 1937, issued July 28, 1942, as Patent No.

2,291,011, having to do with a speed governor.`

Referring to Fig. 1, three motors which are to have their speeds controlled, are indicated at 6,

These are constant displacement motors. Three variable displacement pumps 8, 3 and I0 are arranged to direct iiuid-'JA under pressurel respectively to the motors 5, 6 and 1. Each of these variable displacement pumps 8, 9 and I0 are provided with pump yokes or movable members II, I2 and I3 respectively, these members being adapted to vary the displacement of the particular pump on which they are located. Each pump takes liquid from a tank pipeAI4 and directs it to a' pressure pipe vI5 leadingto a motor, each motor is also provided with a tank pipe I6. Each pump is provided with a drive shaft I1 which is driven by a suitable power source. -The motors 5, 6 and 1 are provided, respectively, with operating shaftsi25, 26 and 21.

Referring now to the apparatus which controls the speed of the operating shafts of the motors, it will be understood that the speed of each particular motor is dependent on the volume of liquid which is directed to the motor from the variable delivery pumps. The volume output of the variable delivery pumps 8, 3 and I0 is directly dependent on the position of the pump yokes II,

I2 and vI3 which controlk the displacement of the pumps. This type 'of pump is well known.- Cyllinders 28, 28 and 30 are provided to control respectively the position of the pump yokes Il, I2 and I3. A piston 3.I is disposed in each of the piston rod 32 extending through one end of the cylinder and connectedto a respective pump yoke by a link 33. Springs 34 urge thepiston 3l and the pump yokes II, I2 and I3 to the right to the maximum volume position of the yokes as viewed in the drawing.

Constant delivery pumps 35, 36 and 31 are 1ocated to. be driven respectively bymotors 5, 6 and l through belts 38 and suitable pulleys attached to the output shafts 25, 26 and 21 and the drive shafts of the pumps 35, 36 and 31.'. Three iiow control devices 40, 4I and 42 are arranged adjacently and connected respectively to output pipes 43, 44 and 46 of constantdisplacement pumps 35, 36 and 3l. A conduit 46 connects the cylinder 28 with pipe 43 so thatl the piston 3'I in Fig. 2.k Fluid from line 44 and pump 36 enters valve 4I at port 60 and passes into a chamber Il. In this chamber'is a piston valve 52 which is this point on. the speedot each of the-,shafts may v Displacement or connected to a piston 53 through a rod 54. A spring 55 urges the piston 53 downward. The piston 52 is adapted to close a valve opening 56 when in its uppermost position. 'I'he valve opening 56 lies between the entrance chamber 5l and a chamber 51. Between the chamber 51 and an outlet port 58 to the tank is a throttle valve 50 shown in section. This valve l is shown in Fig. 3 and consists of a cylindrical bar adapted to pass through ow control units 40, 4l and 42. The bar is identically recessed at three points 5i, 62 and 62 so that a passageway may be provided between chamber'51 and outlet port 5l. A turning of the valve bar 50 will close the throttle opening between chamber '51 and port 58 as will be seen from Fig. 2. The underside of piston 53 is connectedto chamber 51 through a passageway 54 shown in dotted lines in Fig. 2. The outlet port 58 is connected to the top of piston 53 through a passageway 65. The operation of this flow control device is identical with the valve described in copending application, Serial No. 543,908, led June 12, 1931, now abandoned. The valve is so designed that there will be a constant pressure drop across the throttle valve Sli, the amount of this drop being controlled by of fixed displacement motors, a work shaft, on-

the adjustment of spring 55. An adjustment bolt 66 for spring 55 is locked in position by a cap 61. The throttle action which occurs at valve 60 causes a pressure in chamber 51 which acts on the bottom of pistons 52 and 53 'to exert a When this the spring lifting force on the valve piston. force becomes suillcient to overcome 55, the valve opening 56 will be closed thus cutting down the pressure inrchamber 51. In this A.

way an equilibrium is reached which results in a constant pressure in chambers 5i and 51.v

Referring to the circuit shown in Fig. 1, when pumps 8, 9 and I0 are operating to direct pressure to linesl5 and to motors 5, 6 and 1, respectively, there will be a discharge from pumps 35, 25 and 31. Since each of the flow control outlets 58 are and yet the speed of all lthree could be changed simultaneously, maintainingthe ratio established, by a shifting of the bar 55. We claim:

1. In a hydraulic power system,.a plurality each of said motors, a plurality of variable delivery pumps respectively hydraulically connected with the motors, a movable part on each of said pumps for controlling the delivery of pressure iluid to said motors, a plurality of control pumps,

each of said work shafts respectively driving a control pump, a group of metering valves respectively connected to the pressure outlets of the control pumps, each of said valves having a throttle valve opening and a pressure responsive member for controlling the pressure drop across said opening, means for regulating said pressure responsive member to control flow through said throttle valve opening, a member common to each of .said metering valves located in said throttle valve opening for adjusting the size' thereof and flow therethrough, a plurality-of pressure responsive means respectively connected hydraulically to the control pump outlets and each operably connected respectively with the movable part of a variable delivery pump, and means urging each said movable part to a maximum volume position, whereby pressure liquid from the control pumps will tend to urge connected to the tank, there will be a constant pressure maintained in pipes 43, 44 and 45, this pressure being dependent on the setting of spring 55 in each of the flow control units. Through conduits 45, 41 and 48 the pressure in pipes 4I,

44 and 45 will be exerted on pistons 3| in cylinders 28, 29 and 35. Depending on the amount of this pressure, the pistons 3| wlllbe shifted to the left against the springs 24 so that the volume output of the variable displacement pumps 8, 9 and i0 be identical, the spring 55 in each ,rlow control be changed simultaneously by moving the bar 60. This will change 'the throttle opening between the chamber 51 -and the outlet port 52 and consequently change the pressure exist in conduits 43 to 45 and conduits 4i to 4I.

will be increased or reduced depending on the move ent o! the bar50.

In. some cases in the winding of continuous materiau it is desirable to stretch the material and this may be accomplished by increasing the speed ol will be maintained at a definite point.v vIii the speed of sha1-ts 25, 25 and I Iisdesired to one vof the last rollers on which the continuous material is being wound. In the' be adjusted until the which will the pump yokes Il, I2 and i3 win thus be changea and the speed or the system 5,

present circuit vthis may be done by changing lsaid movable parts to a lower volume position andthe setting of said metering valves will control the pressure acting on the pressure re-f a pressure responsive movable member for varying the output speed of' the transmission, a group of metering valves, a plurality f control pumps.' each transmission driving a respective control pump, each control pump delivering liquid to a respective metering valve at 'a volumetric rate proportional to the output speed of its respective transmission and also delivering liquid to a respective movable member, each or lsaid valves having a throttle valve opening and a pressure responsive member for ,controlling the pressure drop l across `said opening, means for regulating said pressureresponsive member to control iiow through said throttle valve opening, a member 'common' to each or said metering valves located in` said throttle valve opening for adjusting the size thereof and flow therethrough.

means urging each movable member to a maxi- 1. mum volume position, whereby pressure liquid-"f from the control pumps will tend'to urge its respective movable member to a lower volume position and the setting of said metering valves will determine the pressure acting onlits respective movable member. f

. KENNETH R. HERMAN JAMES ROBINSQN.

springs 55 in the flow A

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