US1902480A - Hydraulic operator - Google Patents

Description

March 21, 1933. w. J. wooos HYDRAULIC OPERATOR Filed Aug. 15,

Ihvenbori William J. WOOGIS,

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Patented Mar, 21, 1933 UNITED STATES PATENT OFFICE WILLIAM J. WOODS, OF SCmC'I'ADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC A CORPORATION OF NEW YORK mmumo owns-ma Application filed. August 15, 1930. Serial No. 475,424.

My invention relates to improvements in electro-hydraulic operating means of the type described in a copending application of Walter 0. Lum, Serial No. 415,341, filed December 19, 1929 and assigned to the same assignee as the present application.

In devices of the above type a piston operated by a motor driven lmpeller carried thereby moves within a cylinder or casing containing a fluid, such for example as oil. The piston is connected to operate a work engaging member and the load on the work engaging member may' vary between wide limits. When the hydraulic o crating means hereinafter referred to as the operator is heavily loaded, the piston returns to its initial position rapidly upon deenergization of the driving motor thereof, and undesirable stresses and strains may result, since under these conditions the normal dashpot effect is insuflicient to cushion the return movement of the piston under the heavy load. Again in some applications of the hydraulic operator it is desirable to obtain an accentuated dashpot or time delay effect not possible in a standard operator. v Hence, it is the principal object of my invention to cushion the final movement of an electro-hydraulicoperator of the above type to its imtial position without however unduly retarding the entire return movement thereof. q

It is another object of my invention to produce an accentuated dashpot or time delay efiect on the return stroke of the operator.

In the preferred embodiment of my in-' vention I provide a fluid casing or cylinder in which is slidably mounted a plunger or piston whichis caused to move to its upper limit by means of an im eller carried by' the piston proper, the impe ler being .energized by a motor mounted on the casing proper. The piston is attached to a work-engaging mem: .ber extending without the casing and connected to operate some form of apparatus. The. piston is provided with passageways therethrough so that the oil can .pass through the piston as it moves up or down in response to rotation of the impeller or to the load exerted upon the work-engaging member upon deenergization of the impeller. At the bottom of the casing and resiliently supported is, a bafiie member which engages the piston in its downward movement a short distance from the end of its stroke. This bafile cooperates with the iston to close the passageways extending t erethrough and thereby prevents a free flow of oil through the piston proper. The eifect of this operation is to cushion the return of the piston to its lower or initial position. h a modification the piston is provided with studs on which thebaflle is slidably supported at a depth below the piston to give a proper length of stroke. In the drawing, Fig. 1 represents a cross section of my hydraulic operator with the work-engaging member and piston in the upper position. Fig. 2 represents a cross sec: tion of the piston showing the details of the passageways therethrough. Fig. 3 represents a partial cross section of a modification of my hydraulic operator.

In Fig. 1 the casing 10 is filled with oil and'lower position therein. An impeller 13 is rotatably supported in the piston. The

casing 10 is provided with a coverin or cylinder head 11 which supports the electric motor 12 for driving the impeller13 by means of the splined shaft 33. Bearings 34 and 234 are provided for the splinedshaft. A cover 12 having a bea'ring12 therein "is provided for the motor 12. v a

The piston consists of two parts 14 and 21, the upper portion21 having extensions 22 and 23 thereon for supporting the push rods 24 and 25 which are: connected to the bridging member 31 supporting. the work engaging eye 32. Surrounding the push rods and supported .by the extensions 22 and 23 are the stop members 29 and 30 for limiting the upward movement of the piston 14. These push rods slide in the bearings 26 and 26' carried by the cylinder head 11. The bearings are provided with the grooves or slots 27 and 28 which permit the return of any oil which may have adhered to the push rods and passed by the bearings which act as wipers in the upward movement of the push rods 24 and 25. Clearances are provided in the cylinder head 11 for permitting the push rods to extend therethrough without contact therewith which permits oil carried up by the push rods to return to the casing.

In Fig. 2 is shown a cross section of a piston comprising the two parts 14 and 21. Passageways such as 15 and 16 in the top part of the piston permit oil to contact with the upper part of the impeller 13. Other passageways such as 18 lead oil from above the piston to the cup-shaped portion 17 beneath the impeller. Thus oil is led to the impeller from both the top and the bottom sides thereof. Other passageways such as 19 and 20 ofi'er a passage in a radial direction from the impeller blades to the under side of the piston. Thus when the impeller is rotated by means of the motor 12 oil is drawn into the top and under sides of the impeller and expelled in a radial direction to the passageways 19 and 20.

The bearings 26 and 26' act as wipers for the push rods. However, oil which adheres to the push rods 24 and 25 will return to the space above the bearings because of the clearance in the cylinder head around the push rods. The oil which is there received will then return to the casing by means of the slots 27 and 28 in the bearings.

Mounted in the lower part of the casing 10 is the baflle member 35 resiliently supported by means of springs 36. The whole operator is pivotally supported by means of the eye 37.

The operation of the device is as follows: When it is desired to raise the work engaging' member 32, the motor 12 is energized to rotate the shaft 33 which in turn drives the impeller 13. The oil is received by the impeller through the passageways 15 and 16 to the upper side of the impeller and the passageways such as 18 and 17 to the under side of the impeller and discharged therefrom in a radial direction through the passageways 19 and 20. This causes a pressure differential which exerts afo rce on the bottom of the cylinder to cause it to be raised within the cylinder, the rate at which the piston is raised depending upon the area of the piston, the load exerted thereby, the impeller diameter and the rate of rotation of the motor. When the piston reaches peller spins in the oil without effecting further operation of the device.

'When the motor 12 is deenergized the load thereon causes the pistion to settle, the oil then returning from the under side of the piston through the passageways to the top I side of the piston. Since the flow of oil is restricted by the passageways a dashpot or time delay effect is obtained. When heavily loaded however the piston settles quickl until it'engages the baflie 35. This b e member which isof circular shape engages the under side of. the piston 14 and closes the ports to the passageways 19 and 20, thereits upper position the imby limiting and restricting the flow of oil back through the piston. The springs and the oil together thus cause a cushioning effect of the return of the piston to its lower position and prevent impact between the piston and the casing which prevents undesirable stresses and strains in the operator.

In the view shown in Fig. 3, the baflle member 35' is supported upon the piston 14 by means of studs such as 40 and 40. The baflle is provided with the orifices such as 43 and 44 for a purpose to be described later. The operator in its upper position supports the baflle as shown. When the operator motor is deenergized the piston descends rapidly. Since the bafile is slidably mounted upon the studs 40 and 41 the baffle will be able to move with respect to the piston. When the support offered by the studs is removed upon the descent of the piston to its lower position the baflie will tend to settle but its settling in the oil is very slow in comparison to the movement of the piston and the piston will overtake the baflle in its movement to the bottom of the casing. When this takes place the oil ports in the piston proper are closed by the baflle and only a restricted flow is permitted therethrough by means of the orifices such as 43 and 44 in the baflie proper. These orifices can be either increased or decreased in number or in size to obtain the desired rate of movement of the piston during the last portion of the return stroke. Such a control to obtain an accentuated dashpot efl'ect which results in a slow return is desirable for example in fire pump controls where a quick operation to one position with a slow return is desired. The boss 42 at the bottom of the casing and boss 41 on the bottom of the piston engage each other when the piston is in its lower position to prevent contact of the studs with the bottom of the casing proper. Of course, when the piston reaches its lower position and the pressure beneath the piston becomes equalized the bafile 35' slowly settles to the bottom of the casing and when the motor is again energized to move the piston the studs carry the baflle with it to theposition shown in Fig. 3.

It will thus be seen that I have provided a novel and efficient means for preventing impact in an electro-hydraulic operator of the above type which is certain in action and will prevent shock and strain to the hydraulic operator parts.

The embodiment of the invention illustrated and described herein has been selectedfor the purpose of clearly setting forth the principles involved. It will be apparent, however, that the invention is susceptible of being modified to meet the different conditions encountered in its use, and I, therefore, aim to cover by the appended claims all of the modifications within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electro-hydraulic operator including a fluid-containing cylinder,-a piston operable within said cylinder between two positions and biased to one of said positions, said piston being provided with passageways therethrough, an electrically driven pump having communication with said passageways for controlling the transfer of fluid between opposite sides of the piston through said passageways in one direction to move the piston from its biased position to the other position when said pump is energized, and a movable bafile means cooperating with said piston and effective to control the flow of fluid through the passageways of said piston in the reverse direction for producing a time-delay effect on said piston when said pump is deenergized and said piston moves to the biased position.

2. An electroydraulic operator having a cylinder With a fluid therein, a piston movable in the fluid in said cylinder between two positions and biased to one of said positions, said piston having a fluid passage therethrough, a pump communicating with said passage, an electric motor for operating said pump to transfer fluid through said pas sage in one direction from one side of said piston to the other side of said piston to move said piston from said biased position to the other position when said motor is energized, and a baflle means cooperating with said piston to control the flow of fluid through said passage in the reverse direction from said other side of the piston to said one side of the piston upon deenergization of said motor whereby a time-delay. effect upon the move ment of said piston to its biased position is obtained.

3. A hydraulic operator including a fluid cylinder, a piston movable between two p0 sitions within said cylinder, communicating passages extending through said piston for permitting fluid to pass therethrough, a pump associated with the piston for movement therewith and for communication with said passageways for controlling the transfer of fluid between opposite sides of the piston to control the movement of the piston to one of said positions, said passageways when said piston is moved to the other of said positions producing a dashpot effect to retard movement of said piston to said other position and baflle means resiliently mounted adjacent said other position for closing said passages in said piston for increasing the dashpot effect of saidmember on movement to said other position.

4. An electro-hydraulic operator havin a cylinder with fluid therein, a piston mova le in the fluid in saidcylinder between two positionsand biased to one of said positions, said piston having a fluid. passage therethrough,

a pump assoclated with the piston for movement therewith and having communication with said passage, an electric motorfor operating said pump to transfer the fluid through v the other position when said motor is ener- I gized, and baflie means movably'mounted in the cylinder to cooperate with thepump for controlling the transfer of fluid through said passage in the reverse direction to provide a time delay effect upon movement of the piston from said other position to its biased position when said motor is deenergized.

' 5.- An electro-hydraulic operator havin a cylinder with fluid therein, a piston mova le in the fluid in said cylinder between two positions and biased to one of said positions, a pump associated with the piston for movement therewith and provided with inlet and outlet passages on opposite sides of the piston, an electric motor for operating said pump to transfer the fluid through said passages in one direction between the opposite sides of the piston to control movement of the piston from its biased position to the other position when said motor is energized,

and baflie means cooperating with the pump for controlling the transfer of fluid between I the opposite sides of the piston through said passages in the reverse direction to provide a dashpot efiect upon movement of the piston from the other position to its biased position when said motor is deenergizedr 6. A hydraulic operator including a casing, a fluid therein, a piston within said casing movable between an upper position and a lower position, said piston being biased to its lower position, passageways in said pis ton tor permitting said fluid to pass through said piston upon pump associated with said piston and movable therewith' and having communication movement of said piston, a

with said passageways for transferring the fluid therethrough to move the piston to its upper position, a baflie resiliently mounted near said lower position of said piston for cooperatin with said piston to closethe passageways erein when said piston moves to its lower position, said baflle thus preventing impact of said piston and said casing.

7. An electroydraulic operator includin a casing, a fluid therein, a piston within said casing movable between an upper position and a lower position, said-piston being biased to its lower position, passageways in said piston for permitting fluid to pass through said piston upon movement of said piston, a pump associated with said piston and movable therewith and having communication with said passageways,-an electric motor for driving said pump for transferring the fluid between opposite sides of said piston to move said piston to its upper position when said motor is energized, a baflie slidably supported by said piston and cooperating with said piston to c ose the passageways therein when said piston moves from its upper position to its lower position upon deenergization of said motor, said bafile acting to produce a time-delay action in the movement of said piston to its lower position.

8. An electro-h draulic operator including a casing, a flu1d therein, a piston within said casing movable between an upper position and a lower position, said piston being biased to its lower position, passageways in said piston for permitting said fluid to pass through said piston upon movement of said piston, a pump associated with said piston and movable therewith and having communication with said passageways, and an 7 electric motor for driving said pump for transferring the fluid therethrough to move the piston to its upper osition when said motor is energized, a ba e slidably supported by said piston and cooperating with said piston to close the passageways therein when said piston moves to its lower position upon deenergization of said motor, said baflie being provided with orifices therein for determimng the restricted flow through said piston whereby a time-delay action of the movement of said piston to its lower position is obtained thereby preventing impact of said piston and said casing.

9. An electro-hydraulic operator having a cylinder with fluid therein, a piston movabl in the fluid in said cylinder, a pump associated with the piston for movement therewith and provided with inlet and outlet passages on opposite sides of the piston, an electric motor for said pump for transferring fluid therebetween opposite sides of said piston to move the piston in one direction upon operation of the pump when said motor is energized, means for biasing the piston for movement in the other direction when operation of the pump is stopped upon deenergization of said motor and baflie means cooperating with the outlet passages of the pump for providing a dashpot effect in the movement of the piston in said other direction.

In witness whereof, I have hereunto set my hand this 14th day of August, 1930.

WILLIAM J. WOODS.

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