US2457834A

US2457834A - Control device for vacuum cylinders

Info

Publication number: US2457834A
Application number: US624633A
Authority: US
Inventors: Howard E Ricketson
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-10-25
Filing date: 1945-10-25
Publication date: 1949-01-04
Anticipated expiration: 1966-01-04

Description

Jan. 4, 1949. H. E. RICKETSON .CJNTROL DEVICE FOR VACUUM CYLINDERS Fild Oct. 25. 1945 glnuanfo Howard E. Riclceson/ l'l'o: new

Patented Jan. 4, 1949 UNITED sTATEs PATENT orrlcE comun DEVICE Fon vacuum crLmnEns Howard E. mere-tseu, United siam Anny Application October 25, 1945. Serial No. 624.633 s claims. (ci. 12T-ss) (Granted undelnie et or Maren s, lass. u amended April 30, 1928; 870 0. G. 757) The invention described herein may be manufactured and used by or for the Goverment for governmental purposes, without payment to me of any royalty thereon.

This invention relates to vacuum cylinders and more particularly to control devices therefor. Such cylinders are utilized for -many purposes: and either the piston or the cylinder itself may move under the influence of the vacuum while 'the other element remains stationary.

Generally stated, it is old in the art to employ vacuum cylinders with control devices for adjusting its speed of operation, but such devices are usually designed to eiIect an adjustment which does not vary throughout the stroke of the movable element.

I have found that in numerous installations greatly improved results may be obtained by arranging for the movable element to travel at progressively slower speeds along the length of its stroke. More specifically, this will result in the cushioning of undesirable shock without appreciable retardation of the operating cycle.

In vacuum-controlled excavating machines of the shovel-and-crane type, for example, considerable dililculty is presented for the reason that because of the necessity of having to exhaust the air from the line and from the vacuum cylinder before the clutch will engage there develops a time lag between the instant thatthe operator opens the control valve and thev moment the clutch actually engages: and during this time lag, the operator opens the control valve too wide. This excessive opening of the control valve causes the ultimate sharp egagement of the clutch with a resultant jerky and violent operation accompanied by injurious shock to the machine.

Certain expedients (such as the use of a restrictor at a suitable point in the vacuum line) result in smoothing out the engagement of the clutch; but the use thereof slows down the operation of the vacuum cylinder and increases the time lag both on engagement and also on the release of the clutch. This is objectionable from an operational point of View.

It is among the objects of the present invention to provide a control device for vacuum cylinders which will result in an even action without increase in time lag.

Another object is to so control the air input of a device of the class described as to cause progressively decreasing speed in the operating stroke to thereby prevent injury from suddenly imposed strains, and at the same time, provide for a rapid output or exhaust on the return movement.

Another object is the provision of a vacuum cylinder wherein the admission of air under atmospheric pressure is metered, together with means for eiecting the rapid exhaust referred to. 60.

With such construction and arrangement, the operator ot the machine (for example, the shoveland-crane previously mentioned) may move the control valve wide open, but the clutch will engage smoothly and only as fast as the metering eiiect will permit; while the rapid exhaust means enables instantaneous release.

Still another object is to provide a device of the class described which is cheap and easy to manufacture and durable in service.

'I'he invention, then. comprises the features hereinafter fully described. and as particularly pointed out in the claims..the following description and the annexed drawingssetting forth inv detail certain illustrative embodiments of the invention, these being v'indicative of but4 several of numerous ways in which the principles of the invention may be employed.

In said drawings:

Figure I is a longitudinal view, mostly kin section, illustrating'the association of the operating instrumentaiities `of---the device. of the-invention wth the vacuum cylinder and the pistons disposed therein;

Figure 2 is a view similar to that of Fig.. 1, but discloses a permissive modification: and

Figure 3 is a sectional view on the line 3-3 of Fig. 2.

Referring more'particularlyto the drawings the numeral 2 designates a vacuum lingel from a suitable source of low pressme, the said line bein'g connected, to a vacuum cylinder 3. In the manner well known in the art. the vacuum cylinder 3 is provided with a connector 4 by which the said cylinder is connected to the element which it is intended to operate, for example, the operating lever of a mechanical clutch (not shown). Within the vacuum cylinder 3 is a piston 5 to which there is connected a piston rod 6, the latter projecting from the said cylinder as shown. This piston rod 6 may, if desired, be conveniently anchored and thus rendered immobile.

The vacuum cylinder 3 and its interiorly disposed piston 5 are ci more or less conventional design. However, the piston rod 6 is of modied design as will appear. This piston rod 6 is provided with a central passage 9 which is closed at its ends. The inner end ot the central passage 9 communicates with a right angularly extending port ill which in turn communicates with the inside of the vacuum cylinder 3 at a point immediately adjacent the proximate face oi the piston 5. At appropriate points along its length, the piston rod E is provided with air inlet ports, as shown at l2, i3 and I4, the latter beingdispos'ed adjacent the outer end of the said piston rod.

'Both ends of the vacuum cylinder 3 are closed as shown at Ivand l1, and the closure l1 from which the piston rod 6 projects is provided with a centrally disposed sleeve I8 which serves as a bearing. The outer end of this centrally disposed sleeve I8 projects from the closure I1 and carries an annularly rotatable collar which is secured against rotation and/or longitudinal movement by a set screw 2|. As shown in Figure l the annular collar 20 closely embraces the piston rod 6 and is provided with a peripheral recess which is defined by a longitudinally extending wall 22 and a fiat angular wall 23 which extends inwardly and converges upon the longitudinally extending wall 22. Thus, the

walls

22 and 23 of the collar 2|) define a right-angled triangle, the apex of which lies inwardly of the outer end of the said collar.

Accordingly, to the foregoing construction and arrangement, the atmospheric air entering the vacuum cylinder 3 is metered through the air inlet ports I2, I3 and I4 in the piston rod 8. The hole i4 is always exposed, but extent of exposure of the holes I2 and I3 is regulated by the adjustment of the rotational position of the triangular recess in the annular collar 2D. Thus, when all three holes (i. e. I2, -I3 and I4) are exposed, the vacuum inlet end of the vacuum cylinder 3 is drawn toward the piston rod 6 at a rate which is initially very rapid and decreasingly slower as the exposure of the holes and I2 and I3 is foreclosed. This metering effect accomplishes the results referred to hereinbefore.A

In order to assure the quick return of the vacuum cylinder 3 to its initial position, the closure I7 which is on the atmospheric air" side ofthe piston 5, is provided with a quick-operating disk-type of exhaust valve 25 which, upon being operated by the air pressure in the atmospheric air" pressure side of the piston, releases the air andv permits the cylinder to .drop to its initial position under gravity, that is, by its own weight.

In Figure 2 of the drawings there is shown a modified form of metering device; the same comprising a slot 26 which extends from the inner end of the piston rod B to a point adjacent the outer end thereof. This slot 26 is a dove-tail contour, being defined by a fiat bottom 21, and a pair of outwardly convergent iiat side walls 28. Within the dovetail slot 26 there is disposed a slidable wedge 30, the -bottom and side walls of which conform to the size and shape of the corresponding portions of the said slot, as shown in-Figure 3 of the drawings.

outer surface inwardly toward the piston 5. A bushing 32 or other suitable sealing means may be disposed within the sleeve I8 as shown. Whether using either the embodiment of Figure 1, or the permissive modification of Figure 2, the intake of air at atmospheric pressure into the vacuum cylinder 3 is metered to provide for rapidinitial movement followed by progressive decrease as the vacuum cylinder 3 moves toward the piston 5.

Having thus described my invention, what-If claim as new and wish to secure by Letters Patents is:

The wedge formation of the slldable wedge accrues from the tapering of its 2. A vacuum cylinder assembly comprising a vacuum cylinder provided with -a closure at both ends, a piston disposed within said cylinder, means for connecting one end of said cylinder with a source of vacuum, a piston rod extending through the closure at the other end of said cylinder and connected to said piston, a check valve permitting a rapid exhaust flow from the cylinder to the atmosphere carried by the last-named end of said cylinder, said piston rod having a central passage communicating with the adjacent side of said piston and spaced air inlet openings communicating with the atmosphere, and means for closing at least one of said spaced air inlet openings during the operating stroke of said vacu um cylinder.

3. A vacuum cylinder assemblyvcomprising a vacuum cylinder provided witha closure at both ends, a piston disposed within said cylinder, means for connecting one end of said cylinder with a source of vacuum, a piston rod extending through the closure at the other end of said cylinder and connected to said piston, a check valve permitting a rapid exhaust ilow from the cylinder to the atmosphere carried by the last-named end of said cylinder, said piston rod having a central passage communicating with the adjacent side of said piston and spaced air inlet openings communicating with the atmosphere, means for closing at least one of said spaced air inlet openings during the operating stroke of said` vacuum cylinder, said last-namedmeans comprising an adjustable sleeve on the exterior-of said cylinder, and means for adjustably positioning said sleeve to regulatethe extent of operation of at least one of saidl spaced air inlet openings.

4. A vacuum cylinder assembly comprising a vacuum cylinde'nprovided with a closure at both ends, a piston disposed Within said cylinder, means for connecting one" end of said cylinder with a source of vacuum, a piston rod extending through the closure at the other end of said cylinder and connected to said piston, a check valve permitting a rapid exhaust flow from the cylinder to the atmosphere carried by the last-named end of said cylinder, said piston rod having a longitudinal slot, and a wedge disposed in said slot, said wedge being longitudinally adjustable to vary the size of the opening between said slot and the adjacent cylinder closure at any given position in the operating stroke of said vacuum cylinder. H

5. A vacuum cylinder assembly comprising a stationary piston, a closed cylinderreciprocably mounted-on said pistone, a piston rodconnected to saidv piston and extending `exteriorly of said cylinder, means for connecting one end of said cylinder to a source of Vvacuum whereby one side of saidpiston is in 'contact with said vacuum, a check valve mounted; on the other end of Asaid cylinder, said check valve permitting a rapid exhaust flow from the 'cylinder to the atmosphere, and a means for metering atmospheric air to the last mentioned end of said cylinder whereby air may be applied to the other side of said piston.

, HOWARD E. RICKETSON.

. REFERENCES CITED l UNITED sTA'rEs PATENTS Number