US2170702A - Hydraulic operator - Google Patents

Description

Aug. 22, 1939. G. w. wARDwELL. JR 2,170,702

I HYDRAULIC OPERATOR Filed sept. 26, 195e Il Vl,

GoPgeWWaPdw/e U1 Jn i Patented Aug. 22, 1939 UNITED STATES HYDRAULIC OPERATOR George W. Wardwell, Jr., Nichols, Conn., assignor to General Electric Company, a corporation of New York Application September 26, 1936, Serial No. 102,728

7 Claims.

The present invention relates to hydraulic pressure operators of the type having a piston slidable in a cylinder. A

The object of my invention is to provide an improved hydraulic operator of this type which eliminates the danger of spilling liquid from the cylinder when the cylinder is tipped and which also increases the speed of operation of the hydraulic operator.

Hydraulic operators of this type are capable of general use Wherever a pressure stroke is required. For the purpose of illustrating the operation and advantages of the hydraulic operator embodying my invention, Ihave shown it applied to an ironing press where it is used to eifect pressing engagement of the cooperating pressing members.

In the accompanying drawing, Fig. 1 is a side elevation of an ironing machine equipped with a hydraulic operator embodying my invention; Fig. 2 is a sectional View of the hydraulic operator taken on line 2-2 of Fig. 1. Fig. 3 is a sectional view partly broken away, taken on line 3-3 of Fig. 2; and Fig. 4 is a top plan view of the construction for preventing leakage of liquid from the cylinder.

Referring to the drawing, I have shown my invention applied to an ironing machine of the type shown in my application, Serial No. 750,620, filed October 30, 1934, now Patent No. 2,135,266. In this construction, the hydraulic operator is contained Within a cylinder I, having an integral llange 2 supporting the cylinder on the top 3 of a suitable table. The cylinder projects through an opening in the table top and on the lower end of the cylinder is pivoted a carriage 4 having an arm 5 which supports a suitable heated shoe 6. A handle l, for moving the carriage, is attached to the front end of the shoe, where it is conveniently accessible to the operator. The shoe is moved into and out of register with a padded buck 8 by means of pivotal movement of the carriage. The rearward movement of the carriage is limited by a toggle comprising links 9 and III, respectively pivoted to the cylinder and to the carriage. The rearward movement of the carriage is cushioned by a tension spring I I arranged between the cylinder andthe common pivot point of the toggle links 9 and Il).

The cylinder is filled to the level indicated by the dotted line I2 in Fig. 2 with a suitable liquid such as oil of the desired viscosity. Within the cylinder is a piston having a piston head I3 irnmersed in the liquid. To the lower side of the piston head is bolted a plate I4, which cooperates with the piston head to provide a groove for a piston ring I 5 and to provide a space serving as a housing for an impeller I6, l'lXed to the lower end of a shaft Il. The impeller and the shaft are supported by va spring pressed ball I8, carried 5 by the plate I4, and are alsol supported by a projection I9 on the impeller which ts in a complementary recess in the plate I4. Holes I9a are provided in the projection I9 for the purpose of relieving pressure which may build up on the 10 under side of the impeller during its rotation. The inlet to the impeller is provided by a central opening 20 in the piston head and the outlet from the impeller is provided by openings 2| arranged around the periphery of the plate I4. The liquid which flows through the inletl opening 20 enters from the cylinder through openings 22 in the side Walls of a cylindrical body 22a of the piston to which the piston head is secured, and flows between a baille plate 23 and upper side of the piston head to the inlet 20. Varies 24 are provided on the upper side of the piston head to guide the liquid to the inlet, and to prevent swirling of the liquid at the inlet. The baffle plate 23 rests on the upper edge of the vanes 24 and is held in place by projections 25 on the member 22a which are peened over the edge of the baffle plate. The baille plate is provided with ears 2B which lit in the openingsY 22 and locate the baille plate.

With this construction, rotation of the shaft Il causes the liquid to be drawn from the upper side of the piston head I3 through the inlet opening 20 and to be forced through the dicharge openings 2| to the space between the piston head and the bottom Wall of the cylinder, thus creating pressure which causes the piston to be forced upward in the cylinder. When rotation of the shaft Il is stopped, the liquid flows in the reverse direction from the lower side of the piston head I3 through the openings 2| and 20 to the upper side 40 of the piston head, thereby permitting the piston to move downward in the cylinder.

The shaft I'I is rotated by an electric motor having its rotatable element 2l fixed to the shaft Il and its stationary element 28 carried in a hous- 45 ing 29 which is integral with the body 22a of the piston. The housing 29 is provided with a bottom wall 3l! carrying bearing 3I in which the shaft Il is journaled. The bearing 3I is located so as to dip in the ,oil when the piston is down, thus providing'reserve lubrication. A seal may be provided to preventleakage of oil into the interior of the motor housing. The Wall 30 provides a closurefor the motor housing 29 whichV prevents the leakage of the liquid into the motor windings. The buck 8 is suitably supported on the upper end of the housing 29. spilling of liquid from the cylinder is prevented by a piston ring 32 which is carried in a groove 33 in a collar 34 secured to the outside of the motor housing 29. The piston ring is axially slidable in the groove 33 so that the friction between the cylinder walls and the piston ring causes the piston ring to engage the lower edge of the groove 33 during upward movement of the piston and to engage the upper edge of the groove during downward movement of the piston. In the collar 34 are vent openings 35 which extend from the upper side of the collar to the lower edge of the groove 33. When the piston ring 32 engages the lower edge of the groove 33, an air and oil tight seal is formed between the piston ring 32, the collar 33, and the motor housing I29, completely sealing the upper end of the cylinder. From one aspect, these parts then serve as a piston head which is spaced above the liquid level in the cylinder. During upward movement of the piston, a vacuum is therefore created between the surface of the liquid and the piston ring 32. This vacuum tends to draw any oil out of the motor housing which may seep between the shaft Il and the bearing 3| during rotation of the shaft. When the motor is stopped, the piston falls due to the action of gravity and also due to the difference in pressure between the top and bottom sides of collar 34. The vacuum created on the underside of the collar 34 during the upward movement of the piston therefore assists the downward or return movement of the piston, If a perfect seal is obtained between the collar 34 and the walls of the cylinder there will be no ow of air to the space below the collar 34 either during the upward stroke on the piston or while the piston is at the top of its stroke. The volume of air below the collar 34 will under these conditions remain constant. If a perfect seal is not obtained there will be `some leakage of air to the space below the collar when the piston is at the top of its stroke. rThis will produce an increased amount of air below the collar which might prevent the full return of the piston to the bottom of the cylinder.

The ventholes 35 provided in the collar 34 allow the escape of any excess air which might be trapped below the collar and. prevent or retard the downward movement of the piston. The vent holes 35 function when the pressure below the collar 34 is greater than atmospheric pressure. In addition to the air pressures acting on the piston ring 32 there is also a force due to friction between the piston ring and the side walls of the cylinder. As the piston nears its lower position, the force of friction on the piston ring may be suiiicient to move the piston ring upward in the groove 33 while a vacuum is still present below the piston ring. If this is done there will be an inward rush of air to the space below the piston ring. rihis arrangement is particularly effective in preventing the escape of fumes which may result from the churning of the oil by the impeller.

In the use of the ironing machine, the material to be ironed is arranged on the upper surface of the buck 8 and the heated shoe 6 is moved to a position in register with buck 8 as shown in Fig. l. Power is then supplied to the electric motor starting the rotation of the shaft I1 which causes the impeller to draw liquid from the upper side of the piston head I3 through the inlet opening 2Q, and to force the liquid through the discharge openings 2|, thereby building up a pressure between the cylinder and lower side of the piston head I3 which causes the piston to be raised in the cylinder. Due to the time necessary for accelerating the electric motor there is a 'time lag in the building up of pressure by the impeller, which causes the upward movement of the piston to start smoothly. The upward movement of the piston continues until the buck is moved into pressing engagement with the shoe, and the resistance offered by the shoe t`o further movement of the buck balances the pressure created by the impeller. The pressure continues as long as the motor is energized. During the upward movement of the piston, the friction between the piston ring 32 and the cylinder wall and the tendency for air to pass from the top to bottom side of the collar 34 causes the piston ring to be moved into engagement with the lower edge of the groove 33, thereby sealing the vent openings 35 and causing a vacuum to be created between the piston ring 32 and the surface of the liquid.

To release the pressure between the buck and the shoe, the electric motor is deenergized, thus stopping the rotation of the shaft Il. The weight carried by the piston then forces that liquid from the under side of the piston head i3 through the openings 2l and V2l) to the upper side of the piston head, thereby permitting the piston to move downward in the cylinder. Due to the vacuum created betweenv the piston ring 32 and the surface of the liquid, the downward movement of the piston is accelerated by the force of the atmospheric pressure which acts on the upper side of the motor housing 29 and the collar 34. During the downward movement of the piston the piston ring is held against the lower side of thegroove 33 by the difference in pressure acting on the upper and lower sides of the ring thereby maintaining an air-tight seal between the collar 34 and the walls of the cylinder. As the piston nears its lowered position the pressure differential decreases andthe friction between the piston ring andthe cylinder walls and the pressure acting on the underside of the ring causes the ringv to-be moved upward in the groove 33 thereby venting the space below the collar 34 to the atmosphere. This prevents the trapping of air belowthe collar 34 which might prevent the full return movement of the piston. After the trapped air is discharged through the openings 35, the piston ring moves downward in the groove to a position sealing these openings. It is therefore apparent that spilling of the liquid from the cylinder is effectively prevented by the ring 33.

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

1. In combination, a liquid containing cylinder, a piston having a head immersed in the liquid, means for forcing liquid from the upper to the lower side of the piston head for forcing the piston upward in the cylinder, sealing means for preventing leakage of the liquid including a piston ring engaging the cylinder walls above the liquid level, a groove in the piston in which the ring is axially slidable whereby it engages the lower and upper sides of the groove respectively during upward and downward movement of the piston, and a vent opening to the atmosphere arranged to be sealed when said ring engages the lower side of said groove whereby a partial vacuum is created between the ring and the liquid during upward movement of the piston, said vent being opened when the ring moves away from the lower side of the groove whereby the vent is opened duringV downward movement of the piston.

2. In combination, a liquid containing cylinder, a piston having a head immersed in the liquid, means for forcing liquid from one side to the other side of the piston head for moving the piston upward and downward in the cylinder, sealingV means between the piston and cylinder above the liquid level including a piston ring carried by the piston for preventing leakage of liquid upon tipping of the cylinder, a normally closed vent from the atmosphere to the space between the piston ring and the liquid, and means for opening said vent to prevent air pressure in excess of atmospheric pressure in said space, said vent being closed to the atmosphere during upward movement of the piston and open to the atmosphere during downward movement of the piston.

3. In combination, a liquid containing cylinder, a piston having a head immersed in the liquid and having a second head above the liquid level with its upper surface exposed to atmospheric pressure, a piston ring carried by said second head and engaging the cylinder for preventing leakage of liquid upon tipping of the cylinder, means for forcing the liquid from one side to the other side of the immersed head for moving the piston upward and downward in the cylinder, and means including a vent opening in said second head leading from the atmosphere to the space above the liquid for preventing excess air pressure in said space, said vent being closed to the atmosphere during upward movement of the piston and open to the atmosphere during downward movement of the piston.

4. In combination, a liquid containing cylinder, a piston having a head immersed in the liquid, an impeller having its inlet in the upper side and its outlet on the lower side of the piston head, an electric motor for rotating the impeller whereby the piston will be moved upward in the cylinder, sealing means between the piston and cylinder above the liquid level including a piston ring carried by the piston for preventing leakage of liquid upon tipping of the cylinder, a normally closed vent from the atmosphere to the space between the piston ring and the liquid, and means for opening said vent to prevent air pressure in excess of atmospheric pressure in said space, said vent being closed to the atmosphere during upward movement of the piston and open to the atmosphere during downward movement of the piston.

5. In combination, a liquid containing cylinder, a piston having a head immersed in the liquid, an impeller having its inlet on the upper side and its outlet on the lower side of the piston head, an electric motor for rotating the impeller whereby the piston will be moved upward in the cylinder, sealing means for preventing leakage of liquid including a piston ring engaging the cylinder walls above the liquid level, a groove in the piston in which the ring is axially slidable whereby it engages the lower and upper sides of the groove respectively during upward and downward movement of the piston, and a vent opening to the atmosphere arranged to be sealed when said ring engages the lower side of said groove whereby a partial vacuum is created between the ring and the liquid during upward movement of the piston, said vent being opened when the ring moves away from the lower side of the groove whereby the vent is opened during downward movement of the piston.

6. In combination, a liquid containing cylinder, a piston having a head immersed in the liquid, and having a second head above the liquid level with its surface exposed to atmospheric pressure, an impeller having its inlet on the upper and its outlet on the lower side of the immersed head, an electric motor for rotating the impeller whereby the piston will be forced upward in the cylinder, said motor having a bearing in the space below the second head, sealing means for preventing the leakage of liquid including a piston ring carried in a groove in said second head, said ring being axially slidable in said groove whereby it engages the lower and upper sides of the groove respectively during upward and downward movement of the piston, and a vent opening'to the atmosphere arranged to be sealed when said ring engages the lower side of said groove whereby a partial vacuum is created between the ring and the liquid during upward movement of the piston, said vent being opened when the ring moves away from the lower side of the groove whereby the vent is opened during downward movement of the piston.

1. In combination, a liquid containing cylinder, a piston having a head immersed in the liquid and having a second head above the liquid level with its surface exposed to atmospheric pressure, an impeller having its inlet on the upper and its outlet on the lower side of the immersed head, an electric motor for rotating the impeller whereby the piston will be forced upward in the cylinder, said motor having a bearing in the space below the second head, sealing means between the piston and cylinder above the liquid level forr preventing leakage of the liquid, a vent in said second head from the atmosphere to the space above the liquid, means for closing said vent during upward movement of the piston, whereby a partial vacuum will be created in the space between the second head and the liquid during upward movement of the piston, and means for opening the vent to prevent pressure in excess of atmospheric pressure in the space below the second head during downward movement of the piston.

GEORGE W. WARDWELL, J R.

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