US2242676A - Hydraulic actuator - Google Patents

Description

May 20, 1941. A. E. JuRs HYDRAULIC ACTUATOR Filed oet. s1, 193e.-

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HYDRAULIC AcTUAToR v l Filed Oct. 31, 1938 2 Sheets-Sheetl 2 'F'IIE E ATTORNEY Bfe W -cessful commercial use.

Patented May 2Q, 1941 HYDRAULIC ACTUATOR Albert E. Jurs, Piedmont, Calif.

Application October'l, 1938, Serial No. 237,837

1 Claim.

This invention relates generally to hydraulic systems making use of a hydraulic operato-r or actuator, in conjunction with one or more devices adapted to be operated by application of liquid under pressure. More particularly the invention relates to systems for effecting operation of valve units from a remote point, and is of particular value as applied to tank trucks or cars, for controlling the dispensing o-f inflammable liquids such as gasoline from tanks or tank compartments.

In my Patent No. 1,976,445, granted October 9, 1934, there is disclosed a system for effecting the hydraulic operation of valve units in order to control the dispensing of iniiamm-able liquids such as gasoline from tanks or tank compartments. The system as disclosed in that patent is characterized' by the use of a by-pass, whereby when the pressure of the liquid as applied to one or more of the valve units exceeds a predetermined value, liquid is by-passed to an auxiliary reservoir. Many systems of the type disclosed in said Patent 1,976,445, are now in suc- When gravity iiow discharge' conduits are attached to the outlets of the valveV units, the valve units will remain in open positions as long as the operating handle of the hydraulic actuator remains in its actuated position. However, when the suction side of a pump is connected to a liquid discharge conduit, as is sometimes the case, a valve unit may be closed or partially closed even while the opwating handle of the actuator remains in actuated position. This is because lthe diierential pressure tending to urge the valve member of the Valve unit towards closed position is of such magnitude as to cause the pressure of the hydraulic operating liquid to exceed the predetermined value for which the by-pass is set. Under such circumstances it is not feasible tc merely set the by-pass for a higher pressure, because such an adjustment would require excessive force for moving the handle of the hydraulic actuator, and in addition the hydraulic connections and the pressure cells of the valve units might be damaged by excessive pressure.

It is an object or" the present invention to provide a system which will overcome the dihiculty outlined above, and which will prevent the bypassing of liquid back to the auxiliary reservoir when the handle of the actuator is in actuated position. This is accomplished by valve means for controlling the by-pass, with an automatic arrangement whereby the by-pass passage is i.

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closed when the handle of the actuator is swung to actuated position.

Further objects of the invention will appear from the following description in which the preferred embodiment of .the invention has been disclosed in detail in conjunction with the accompanying drawings.

Referring to the drawings:

Fig. 1 is a side elevational View, in cross-section,r illustrating an operator or actuator in accordance with the present invention.

Fig. 2 is a diagrammatic lay-our, showing the manner in which the actuator of Fig. 1 is applied in a valve system.

Fig. 3 is a cross-sectional detail showing the operating parts of the device in a different operating position.

Fig. 4 is a cross-sectional detail showing a modication of the invention.

The hydraulic actuator as illustrated in Figs. 1 and 3, consists of a casing I the interior of Which is bored to form a cylinder II'. Fitted within the cylinder I I there is a piston I2, which is urged upwardly by compression spring I3'.

The representative type of piston illustrated is of simple design, consisting of a hollow body I4, and a lower end I. which is attached rto the body by means of a threaded connection Il. A cup washer I3 establishes a seal with the side walls of the cylinder II, and is clamped between opposed flanges formed between the body i4 and the end wall I5. A small check valve I9 is mounted upon the piston part I6, and the ball 2| oi this check valve closes against the pressure below the piston, when `the piston is moved downwardly.

At the upper end of the cylinder I I the casing lil forms an auxiliary liquid reservoir 22. The interior of the piston I2 communicates with the auxiliary reservoir 22, through the port 23, Also a duct 2i in conjunction with a port 26, estabilishes communication between the auxiliary reservoir 22 and the pressure chamber 27 below the piston I 2, when the piston is in its uppermost or released position, as illustrated in Fig. 1.

For the purpose of forcing the piston downwardly to a definite actuating position, operating mechanism is provided which includes the operating handle 28. This handle is mounted upon the outer end of a rock shaft 29, which in turn is journalled in the side walls of the casing I9. Within the casing there is a toggle linkage connected to shaft 29, which includes the arm 3| which is attached to shaft 29, a link 32 having a pivotal connection 3d with arm 3|, and a link 33 having one end of the same pivotally connected to link 32, and the other end provided with a pivotal connection 34 to the casing. The pivot pin 36 forming the pivotal connection between links 32 and 33, also carries a thrust roller 31, adapted to engage a hardened pad 38 secured to the upper end of piston I2. It will be apparent that when the operating handle 28 is swung downwardly to its actuated position, arm 3| is swung counter-clockwise to the position illustrated in Fig. 3, whereby roller 31 forcesy the piston |2 downwardly. As shown in Fig. 3, for full actuated position the center of pivot pin 30 is just past dead-center position with respect to the centers of shaft 29 and pin 36. Therefore the parts are locked in actuated position until the operator again swings handle 28 upwardly.

For the purpose of forming a by-pass between the pressure chamber 21 and the auxiliary reser- Voir 22, the casing lll is provided with a duct or passage 4|, the lower end of which communicates with chamber 21, below the lowermost position of the piston I2. The upper end of passage 4| communicates through the additional ducts 42, 43 and 44 with the auxiliary reservoir 22. For convenience the ducts 42 and 43 are shown formed within a separate casing part or fitting 46, thereby facilitating the mounting and assembly of valve parts, as will be presently explained. A valve seat 41 is formed in the body part 46, and cooperates with the ball check 48. This ball is urged against its seat by the compression spring 49, the upper end of which is seated upon the adjustable screw 5|. By removing the plug 52, screw 5| can be adjusted to secure the desired tension. It is the ball check 48, and its spring 49, which largely determines the pressure above which liquid is permitted to bypass from pressure chamber 21, back to the auxiliary reservoir.

. An additional valve seat 53 is formed in the body part 46, and cooperates with the ball 54. This ball is forced against its seat by means actuated when the handle 28 is moved to actuated position. The simple means illustrated in this instance consists of a pin 56, slidably mounted within the casing, and in substantial alignment with the seat 53. One end of this pin is provided with a head 51 for engagement with the ball 54, and a compression spring 58 normally urges pin 56 towards the ball. The other end 59 of the pin extends within the auxiliary reservoir 22, and is adapted to be engaged by shoulder 6| formed on the arm 3|. Thus when the arm 3| is in the position corresponding to actuated-position of the lever 28, shoulder 6| enga-ges the end 59 of pin 56, thus continuously urging this pin against ball 54 and continuously urging the ball against the seat 53. When the pin 56 is not so engaged by the shoulder 6|, pressure of liquid can force ball 54 away from its seat, to by-pass liquid back to the auxiliary chamber 22.

Fig. 2 illustrates the hydraulic actuator described above, incorporated in a hydraulic valve system of the type disclosed in said Patent 1,976,445. The individual valves 63 are shown mounted within the bottom walls of the tank compartment 64. These Valves may connect with individual outflow conduits, or a common discharge conduit 66. The lower end of the actuator casing i6 is shown connected by pipe 61 with a selecting valve 68, which in turn is connected by the pipes 69 with the various valve units 63. A bleed pipe 1| also connects the selecting Valve 68 with the auxiliary chamber 22 of the actuator casing I6. 'Ihe selecting valve 68 is shown including three selecting knobs A, B and C, in the same manner as illustrated in Fig. 8 of said Patent 1,976,445. As described in said patent by changing the settingof knobs A, B and C, any one of the valve units 63 may be selected for individual operation, or any two or more of the valve units may be selected as a group for simultaneous operation, or all of the valve units may be operated in unison. A valve unit not selectedl for operation is placed in communication with pipe 1I and the auxiliary liquid reservoir 22, through its connecting pipe 69. The liquid used in the system may be a suitable lubricating oil and a suilicient excess of oil is ordinarily maintained in reservoir 22 to well cover the upper end of the piston, when the piston is in its uppermost or released position.

Gperation of the equipment described above can be reviewed as follows: Assuming that an operator has set the selecting valve 68 to select certain ones of the valve units for operation, the operator pulls down upon the handle 28 whereby the piston l2 moves downwardly to displace liquid from the chamber 21. Liquid is thus delivered under pressure to the valve units selected for operation, whereby these units are moved to open positions. The volumetric displacement aiorded by the piston when it moves vfrom released to actuated positions, is such as to afford sunicient liquid under pressure for operation of all of the valve units simultaneously. Therefore when less than all of these units are being operated, the pressure will immediately rise beyond a predetermined value as the piston continues to move downwardly, and after the selected valve units have been moved to full open positions. Thus the pressure of the liquid moves balls 48 and 54 oi their seats against the urge of springs 43 and 58, thus permitting excess liquid to by-pass back into the auxiliary reservoir 22, las the piston completes its movement towards actuated position. As the operating handle 28 reaches actuated position pin 56 is engaged by the shoulder 6| as previously described, and the force thus continuously exerted upon pin 56 serves in effect to lock ball 54 against its seat, to avoid any further Iby-passing. It will :be noted that when the parts are in such position the compression spring |3 tends in eiect to urge arm 3| in a clockwise direction, as viewed in Fig. 3, thereby affording a biasing force urging pin 56 against lball 54, in addition to the fluid pressure urging the piston upwardly. Should any additional forces be applied to the actuated valve units tending to urge these units closed, as for example by connecting the outflow conduit 66 to the intake of a pump, such forces can not be sufficient to cause further by-passing of liquid back to the auxiliary reservoir 22, because of the locking afforded by ball 54. When it is desired to return the valve units to closed position, hand lever 28 is swung back to released position, whereby the piston |2 likewise moves upwardly under the urge of spring 3, to the position illustrated in Fig. 1. During such return movement of the piston ball 2| of the check valve I9 permits flow of liquid through this check valve to the space below the piston.

In the foregoing description I have made reference to two separate valves for controlling bypassing of liquid through the passage 4|. In the arrangement illustrated, both of the balls 48 and 54 will in effect determine the pressure beyond which these `'balls are opened to permit by-passing of liquid. One may dispense with ball check 48, and rely solely upon the ball 54, provided that the seat for this ball is of proper size and provided that the spring 58 is of proper tension to properly determine the maximum pressure required to force the ball from its seat. Such a modication is shown in Fig. 4. In this instance duct 42a, in fitting 46a, leads directly to the seat of ball 54, so that by-passing of liquid is controlled entirely by the one valve ball.

I claim:

In a system of the character described, a hydraulic actuator for selectively operating one ,or more of a plurality of pressure responsive devices, said actuator comprising a iluid pressure chamber, a piston movable between actuated and released position to displace liquid from said chamber, means including a valve member movable between open and closed positions for venting liquid from said chamber when pressure in said chamber exceeds a predetermined value. an operating lever, toggle mechanismv operatively connecting the lever with the piston whereby movements vof the lever between actuated and released positions serves to reciprocate the piston between corresponding positions., spring means for urging the piston toward released position of the same, the toggle mechanism having a dead center position intermediate actuated and released positions of the same, whereby when the lever is moved from released to actuated position it remains locked in actuated position against the pressure of said spring means, and means for transmitting motion from said toggle mechanism to said valve member to close said valve member when said lever is moved past said dead center position to actuated position, thereby preventing venting of liquid from said chamber While the piston is in actuated position.

ALBERT E. JURS.

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