US2811018A - Apparatus for effecting controlled relative displacement between relative movable parts - Google Patents

Description

Oct. 29, 1957 LANE 2,811,018

C. A. APPARATUS FOR EFFECTING CONTROLLED RELATIVE DISPLACEMENT BETWEEN RELATIVELY MOVABLE PARTS Filed Sept. 27, 1956 l I f l l 1%%%%%%%%%%% 1 [1150511505050 1 9 0 0 0 0 0 5% 00 0 21 00000000000 a gggggggggggg 0000000000 0 0 :NVENTOR ATTORNEYS United States Patent APPARATUS FOR EFFECTING CONTROLLED RELATIVE DISPLACEMENT BETWEEN RELA- TIVE MOVABLE PARTS Clayton Arbuthnot Lane, Enfield, England, assignor to The Edison Swan Electric Company Limited, London, England, a British company Application September 27, 1956, Serial No. 612,466

Claims priority, application Great Britain October 10, 1955 7 Claims. (CI. 60-97) This invention relates to apparatus for efiecting controlled relative displacement between relatively movable parts, in particular to apparatus of the kind by which such parts can be constrained to occupy a succession of regularly spaced relative positions arranged in a number of rows displaced laterally wth respect to one another, this being done by producing a stepwise relative movement between the parts from position to position along the rows and at the end of each row efiecting a lateral displacement (corresponding to the distance between adjacent rows) accompanied by a reversal of the direction of the step movement along the rows, so that the several rows are traversed in succession in alternately opposite directions.

Apparatus of the above kind finds one application in the automatic distribution of articles into containers divided into a number of compartments arranged in rows. For instance in an automatic production process articles constituting the end-product could, as a final operation of the process, be distributed under the control of the apparatus into separate compartments of such a container: thus automatically mass produced grids or other components for thermionic valves could in this way be fed'into separate compartments of a storage tray, or valves themselves could be placed in compartmented containers for despatch. Other simlar applications will also come to mind in connection with the packing of eggs, jars, glassware, and many other articles. As a somewhat difierent application, the apparatus could also be used for automatic position control of, say, a machine tool required to produce a regular pattern of holes, slots, markings and so on, on a workpiece.

According to the present invention apparatus of the kind set forth comprises the combination of a pump arranged for intake and delivery of operating fluid for the apparatus on alternate strokes, a primary actuating combination of cylinder and double-sided piston for effecting movement from position to postion along the rows referred to, the swept volume of the primary cylinder being several times greater than that of the pump and a secondary actuating combination of cylinder and double pis ton for effecting displacement from row to row, the two pistons of this secondary combination being axially spaced and arranged so as to occupy alternately, namely at the end of alternate strokes of the secondary combination, a predetermined intermediate location in their cylinder. A first pair of ducts afford communication between the interior of the secondary cylinder at respective positions adjacent and on opposite sides of said intermediate location on the one hand and the interior of the primary cylinder at respective positions on opposite sides of the doublesided piston on the other hand, while a second pair of ducts afford communication with the interior of the secondary cylinder at respective positions adjacent its opposite end and also, through respective one-way valves,

at respective positions adjacent and on opposite sides of .said intermediate location therein. These valves are .ing its limit positions.

.tween its two positions.

arranged for passage of fluid in the direction away from the secondary cylinder. The combination also includes a two-position reversing device eflective according to its position to put one or other of the second pair of ducts in communication with a delivery duct from the pump and the remaining one of these latter ducts in communication with a discharge duct, means being provided for changing the position of the reversing device when the movable primary component reaches a limit position (corresponding to the end of a row) in either direction, thereby to set the apparatus for a stroke of the secondary combination and for reversed movement of the movable component of the primary combination.

As will be described hereinafter in more detail operation of the pump through repeated cycles of intake and delivery of fluid will result in the primary piston or cylinder, which ever may be the movable component of the primary combination, being moved in a series of discrete steps, the direction of these steps being reversed each time the movable primary component reaches one or other of its limits, namely each time the position of the reversing device is changed. At each such time the change of position of the reversing device, which may be a slide valve of some suitable form, results in fluid delivered on the next delivery stroke of the pump being directed into the end of the secondary cylinder opposite that into which it had previously been directed. This action produces a stroke of the secondary combination, so that on subsequent delivery strokes of the pump, fluid is admitted by way of the secondary cylinder to a position in the primary cylinder on the opposite side of the primary piston to that at which it had previously been admitted; accordingly discrete movements of the movable primary component'are effected in the reverse direction until the other limit position is reached and a similar reversing action takes place. As will be appreciated successive actuations of the secondary combination, consequent or successive position changes of the reversing device, will be alternately in opposite directions.

In employing the apparatus for controlling the relative positions of movable parts in the manner set forth, the parts are appropriately coupled to the movable primary component fore relative movement along the rows referred to; they are also appropriately coupled to the movable secondary component through some suitable arrangement for converting the to-and-fro movement of the latter into successive discrete relative movements of the parts in one and the same direction traverse to that of the movement along the rows. The magnitude of the discrete movements of the movable primary component is arranged to correspond to the distance between adjacent relative positions along the rows, While the stroke of the secondary combination is arranged to correspond to the distance between rows.

In carrying out the invention the reversing device may advantageously be electrically actuable between its two positions under control of contacts arranged for operation in response to the movable primary component reach- Thus at each limit position the movable primary component may cause closure of contacts to establish an energising circuit for the appropriate one of two electromagnetic coils provided for respectively actuating the reversing device in opposite directions be- Preferably the circuits for these coils would include master contacts which are actuated during a delivery stroke of the pump to render the limit .contacts ineffectual, that is, to prevent operation of the limit contacts from resulting, during such stroke, in energisation of the appertaining coil and consequent change of position of the reversing device. The purpose of these master contacts is to ensure that the last discrete move- .ment of the movable primary component before it reaches 3 a limit position, which movement will take place on a delivery stroke of the pump, will have been completed before the reversing device can be changed. Conveniently the actuation of such master contacts could be efiected by thev fluidpressure existing on the delivery side of the pump during a delivery stroke.

In order that the invention and its mode ofoperation may be more fully understood reference will now be made to the accompanying drawing in which:

Figs. 1 and 2 illustrate two patterns of movement which the apparatus of the invention may be required to produce, and

Fig. 3 illustrates in schematic sectional form a particular embodiment of apparatus in accordance with the invention.

Referring to the drawing the smallrectangles such as 1 in Fig. 1, corresponding, say, to separate compartments in a container, andthe small diamonds such as 2 in Fig. 2, represent in each case respective positions on one of two. relatively movable parts into correspondence with which, in succession, another part (not shown) is to be brought. In both figures these positions are seen to be arranged in a number of rows extending parallel to the upper and lower edges of the outer rectangles 3, but whereas in Fig. 1 corresponding positions in the several rows are also aligned parallel to the sides of the rectangle 3, in Fig. 2 the positions in each row are staggered in relation to those of the adjacent rows. In either case it is desired to effect relative movement between the parts in steps, first along one row in one direction, then along the next row in the opposite direction, along the following row in the original direction and so on.

In the following, a movement from one position to the next along a row will be referred to as a primary index, and a movement from one row to the next will be termed a secondary index.

Turning now to Fig. 3, the apparatus includes a re ciprocating pump 4 which on one stroke draws in a charge of, say, oil from a reservoir 5 through a one-way valve 6 and on the next stroke expels the charge into a delivery duct 7 through another one-way valve 8. The delivery duct 7 leads into the centre top port of a fiveport slide valve 9 the slide 10 of which can be selectively moved to a left-hand or right-hand position by energisation of an electromagnetic coil 11 or 12 as the case may be. In the right-hand position of the slide, 10, that is, in

the position shown, passages 10' in the slide put the delivery duct 7 and a discharge duct 13 leading to the reservoir 5 into communication respectively with two ducts 14 and 15, whereas in the left-hand position of the slide 1! this is reversed, passages 10 in the slide then putting the delivery duct 7 into communication with the duct 15 and the discharge duct 13 with the duct 14.

A secondary piston and double cylinder combination for effecting the secondary indexing comprises a fixed cylinder 16 and an axially movable piston rod 17 carrying two pistons 18 and 19. These pistons are so spaced apart in relation to the stroke of the piston rod 17 that at one endv of a stroke the piston 13 occupies an intermediate position in the cylinder (as shown) and at the other end of the stroke the piston 19 occupies substantially the same intermediate position. It is arranged that the volume of oil required to produce a complete stroke of the piston rod 17 equals that expelled by the pump 4 on each delivery stroke.

The ducts l4 and 15 communicate directly with the interior of the cylinder 16, at respective positions adjacent its opposite ends, through ducts 20 and 21 in the cylinder walls. The ducts 14 and 15 are also in communication with the interior of the cylinder 16, at respective positions adjacent and on opposite sides of the intermediate position alternately occupied by the pistons 18 and 19, through respective one- way valves 22 and 23 which can pass oil only in the direction away from the cylinder interior. Ducts 24 and 25 extend from thein- 4 terior of the cylinder 16 at respective positions also adja cent and on opposite sides of the intermediate position referred to.

The ducts 24 and 25 lead to a primary combination of cylinder 26 and double-sided piston 27 by which the primary indexing will beelfected. In the arrangement shown the cylinder 26 is axially movable along -a fixed piston rod constituted by two aligned hollow portions 28 carrying between them and having their interiors separated by the piston 27. The ducts 24 and Z5 communicate with the interior of the cylinder 26 respectively through the hollow piston rod portions 28 and ports 29 and 30 on opposite sides of thepiston 27. It is arranged that the volume of oil deliveredby the pump each delivery stroke will on admission to the cylinder 26 move the latter through a fraction of itstotal eifective stroke dependent on the length of primary index required. The etfective stroke of the cylinder 26 isdetermined by normally open limit switches 31 and 32 controlling the establishment of respective energising circuits for the coils 11 and 12 across a suitable supply source connected at the terminals T. These circuits also include, in common, normallyclosed master contacts 33 which are arranged to be opened during each delivery stroke of the pump 4 by a spring-loaded piston plunger 34 operated by the oil pressure on the delivery sideof the pump.

In using the apparatus,primary indexing may be effected directly-by the movement of the primary cylinder 26, whereas the secondary indexing, efliected from the secondary piston rod 17, will require some suitable mechanical, hydraulic or other coupling for converting the toand-fro movements of the piston rod 17 on successive strokes thereof into a succession of step movements all in the same direction and of a magnitude corresponding to thelengths required for, the secondary indices. Thus, for instance, the piston rod 17 may actuate a ratchet wheel 35 by means of two- ratchet bars 36 and 37 spring-urged into engagement with the ratchet wheel at diametrically opposite positions thereon, clockwise rotation of the ratchetwheel, 35 being produced by the bar 36 on left to right movement of the rod 17 and by the bar 37 on right to left movement of the rod 17. A pinion 38 fast with the-ratchetwheel 35 engages a rack 39, which will consequently he stepped unidirectionally (namely left to right as shown) in response to the to-and-fro movement of; the rod 17.

Operation The operation of the apparatus is as follows, it being assumed that the successive relative positions to be occupied by the controlledparts (not shown) are arranged in accordance with the pattern illustrated in Fig. 1.

With the various components in the positions shown in Fig. 3, on the next intake stroke of the pump 4 a measured charge of oil is drawn in from the reservoir 5 and on the subsequent delivery stroke this charge is delivered by way of the duct 7, the reversing valve 9 and the duct 14- to the left-hand end of the secondary cylinder 16. At this timealso the plunger 34 is operated to open the contacts 33. As the piston rod 17 is in its right-hand position the charge of oildoes no work in the cylinder 16 and leaves it by the duct 24 to enter the primary cylinder 26 on the left-hand side of the piston 27. Accordingly the cylinder 26 will be'stepped to the left and it is arranged that the magnitude of the step corresponds to the length of a primar-yindex. The oil displaced from the right-hand side i of the cylinder 26 returns to thereservoir 5 by way of the duct 25, the portion ofv the interior of the secondary cylinder 16 between the pistons 18 and 19, the one-way valve 23, the duct 15, the reversing valve 9 and the discharge duct.13.

A similar action occurs on each subsequent delivery strokeof'the pump'4 until the primary cylinder 26 reaches a limit position corresponding to the end of a row and 5. operates the limit switch .31, this occurring on a delivery stroke of the pump when the contacts 33 will be open.

n the next intake stroke of this pump the contact 33 will close to complete the energising circuit for the coil 11, which will accordingly pull the slide of the reversing valve 9 into its left-hand position. Therefore on the next delivery stroke oil will be directed from the duct 7 through the duct to the right-hand end of the secondary cylinder 16. Due to the restriction of the nonreturn valve 23, the secondary pistons 18 and 19 and their piston rod 17 will then be pushed to the left until the piston 19 takes up the position previously occupied by the piston 18, oil displaced from the left-hand end of the cylinder 16 passing to the reservoir 5 by way of the ducts 14 and 13. Consequently a secondary index is produced.

On the next delivery stroke of the pump 4 oil will be delivered through the duct 15, the right-hand end of the cylinder 16 and the duct 25 to the right-hand end of the primary cylinder, causing the latter to be stepped, this time to the righ, by an amount corresponding to a primary index. Oil displaced at this time from the left-hand end of the cyliner 26 passes to the reservoir 5 by way of the duct 24, the portion of the interior of the cylinder 16 now between the pistons 18 and 19, the one-way valve 22, the duct 14, the reversing valve 9 and the discharge duct 13.

Indexing of the primary cylinder 26 to the right will then continue on subsequent delivery strokes of the pump until the limit switch 32 is operated and the coil 12 energised to pull the slide 10 of the reversing valve 9 back to its right-hand position. In a manner similar to that already described, the secondary pistons 18 and 19 are driven to the right on the next delivery strokeproducing another secondary indexand subsequent delivery strokes step the primary cylinder to the left, the cycle thereafter being repeated so long as reciprocation of the pump continues.

The length of primary index obtained can be adjusted by appropriately increasing or decreasing the stroke of the pump, the distance between the pistons 18 and 19 in the secondary cylinder being adjusted accordingly. The length of the secondary indices can be adjusted by appropriate adjustment of the coupling through which the movement of the secondary piston rod 17 is transmitted.

If the relative positions to be occupied by the controlled parts conform to the pattern of Fig. 2 the required relative movements of the parts can be produced by the apparatus just described by arranging that each primary index requires two step movements of the primary cylinder, that is, two delivery strokes of the pump, whereas each secondary index requires only one delivery stroke.

It is contemplated that the use of the double piston in the secondary cylinder 16 in conjunction with the nonreturn valves such as 22 and 23 may enable the secondary indexing and reversal of direction of the primary indexing to be obtained more simply than by using purely mechanical means. Moreover the hydraulic operation may be smoother and quieter than mechanical, electrical or electro-mechanical operation. The employment of master contacts such as 33 operated hydraulically to prevent energisation of the operating coils for the reversing valve during a delivery stroke of the pump ensures in a simple manner that changing of the position of the reversing valve will be delayed until the last primary index in each row is complete, this being an important condition which is not so readily fulfilled mechanically or electro-mechanically.

As an extension of the invention, a third direction of indexing could be provided for by incorporating between the pump and the reversing valve or other device a further reversing device and another secondary combination of cylinder and double piston together with means for changing-over the piston of this additional reversing device in response to the two parts that are being controlled reaching a limit position in either direction of the relative movement imparted to them'fro'm the existing secondary combination. 5 An application of this extension of the invention would be to the filling of a number of compartmented trays stacked one above the other on an indexing table con which apparatus comprises a primary actuating combination of cylinder and double-sided piston for efiecting movement from position to position along the rows referred to, the swept volume of the primary cylinder being several times greater than that of the pump, a secondary actuating combination of cylinder and double piston for effecting displacement from row to row, the two pistons of this secondary combination being axially spaced and arranged so as to occupy alternately, namely at the end of alternate strokes of the secondary combination, a predetermined intermediate location in their cylinder, 2. pair of ducts aifording communication between the interior of the secondary cylinder at respective positions adjacent and on opposite sides of said intermediate location and the interior of the primary cylinder at respective positions on opposite sides of the double-sided piston, a pair of one-way valves, a further pair of ducts affording communication with the interior ofthe secondary cylinder at respective positions adjacent its opposite ends and also,

through said one-way valves, at respective positions adjacent and on opposite sides of said intermediate location therein, said valves being connected for passage of fluid in the direction away from the secondary cylinder, at two-position reversing device effective according to its position to put one or other of said further ducts in communication with a delivery duct from the pump and the remaining one of said further ducts in communication with a discharge duct, and means for changing the position of the reversing device in response to the movable primary component reaching a limit position (corresponding to the end of a row) in either direction, thereby to set the apparatus for a stroke of the secondary combination and for reversed movement of the movable component of the primary combination.

2. Apparatus as claimed in claim 1 wherein the reversing device is electrically actuable between itstwo positions under control of limit contacts operated in response to the movable component of the primary combination reaching its limit positions.

3. Apparatus as claimed in claim 2 including, for actuating the reversing device in opposite directions between its two positions, respective electromagnetic coils connected in respective energising circuits, the one including limit contacts closed by the movable component of the primary combination at its one limit position and the other including limit contacts closed by said component at its other limit position. a

4. Apparatus as claimed in claim 3 wherein said energising circuits include master contacts actuable during a delivery stroke of the pump to prevent operation of the limit contacts from resulting, during such stroke, in the energisation of said coils to change the position of the reversing device.

5. Apparatus as claimed in claim 4 including, for actuating said master contacts, pressure responsive means responding to fluid pressure existing on the delivery side of the pump.

6. Apparatus as claimed in claim 1 wherein the reverts ingdevice comprises a slide valve having first :and second ports opening to said further ducts, a third port opening to the delivery duct, and two discharge ports opening to the discharge duct, the slide of said valve having'passages defined therein which in one position of the slide aiford communication between the first and third ports and between the second part and one of the discharge ports, and in the other position afiord communication between the second and third ports and between the first port and the; other discharge ports.

7. Apparatus as claimed in claim 1 wherein in the secondary actuating combination the wall of the cylinder has defined therein on opposite sides of said intermediate location respective valvechambers with which saidlfurther ducts communicate and from which ducts extend within the wall in an axial direction to open into the interior of the cylinder adjacent its opposite ends, which chambers also open into the interior of the cylinder adjacent said intermediate location by way of one-way valves accommodated in the chambers.

No references cited.

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