US2379483A - Automatic pulsator for milking machines - Google Patents

Description

July 3, 1945: c. HfHAPeoou AUTOMATIC PULSATOR FOR MILKING MACHINES 2 Sheets-Sheet l Filed Oct. 17, 1940 a xv 7 Aria/7 5x51 Patented July 3, 1945 2,379,483 AUTOMATIC PULSATOR FOB MILKIN MACHINES Cyrus Howard Hapgood, Nutley, N. J assignor to The De Laval Separator Company, New York, N. Y., a corporation of New Jersey Application October 17,1940, Serial nastiness 24 Claims.

The objectof my invention is to provide an automatic pneumatic pulsator, more particularly intended and adapted to that type of milking machines in which alternate high and low pneumatic pulsations (usually atmospheric and partial vacuum) are transmitted to the outer chambers of double chamber teat cups and in which when the pulsator is shifted in one direction two pairs of teat cups are connected with high pressure and the other two pairs with low pressure and in which, when the pulsator is shifted in the other direction, the pressure connections to the two pairs of teat cups are re-'- versed.

The invention also pneumatic pulsator which comprises a valve that not only establishes the alternate connections above specified but that acts as its own motor to effect the reversals of movement required to establish such connections, the most practicable form of which is that'of a piston valve which is subjecte to high pressure on one end and a low pressure on the other end to move it in one direction and which in its movement in that direction makes the pneumaticconnections required to reverse the pressures on its opposite ends to thereby move it in the opposite direction.

While the valve thus acts as its own motor in reversing the connections to the two pairs of teat cups, it would, if uncontrolled, have a high speed vibratory movement. To prevent such uncontrolled movement and to-hold the valve at each end position for a predetermined period of time, I provide a diaphragm that separates the casing in which it is enclosed into two chambers and that is mechanically connected with the motor valve. Before the valve fully completes its movement in either direction, and at the same time that it reverses the pneumatic pressures on its two ends and at the same time that it reverses the pneumatic connections to the two pairs of teat cups, it acts to make the pneumatic connections required to immediately establish great pressure differences in the two chambers, thereby holding the valve from immediate reversing, following which air flows from the high pressure chamber to the low pressure chamber until the pressure difference is reduced to a predetermined minimum, that is, until the pressures are so nearly balanced as to allow the differential pressures on the valve to become effective to reverse it.

From the foregoing descriptionit will be understood that the way in which the diaphragm controls the shift of the valve is the same in relates to that type ofbothdirections of movement of the valve. I-Iowever,;.prior to'(and. during the majorpart' oil the shift ofthe valve in one direction the nearly balanced pressureson' opposite sides of thediaphragm are high and the sudden creation of greatly unbalanced-pressure is effected by connecting. onemof the diaphragm chambers with low'.pressure;-..while prior to .(and during the major part of) the shift ofthe valve in the op- I positedirection the nearly balanced pressures on opposite sides of the diaphragm are low and the sudden creation of a 'greatly unbalanced pres-' sure. is effected by: connecting the same diaphragm .chamberiwith high pressure.

In practical operation the source of high pressure is the atmosphere, while the source of low pressure .is means to establish a partial vacuumequal to half an atmosphere; In the specific embodiment of the invention herein described, one diaphragm chamber is alternately connected with the atmosphere and with what may be convenientlytermed vacuum, while in theother chamber the high pressure, when established therein, nearly equals atmospheric. pressure due to'the flow of, air from thefirst chamberltothe second whenthe, first is connected with the atmosphere,-.while thelow pressure, when ,established, in the second chamber, fallsnearly to half atmospheric pressure'due to the fiOWjOf air from'the'second; chamber to the firstrwhen the latter is connectedwith vacuum. :The greater the difference between the area of the diaphragm and the areas of the piston ends, the more'nearly the pressures in the two chambers approach an exact balance inorder to allow the differential.

pressures ,on the motor ,valve to start its move? I phragm of much larger area than the pressurev ment ineither direction, By makingthedia areas of the motor valve, a large volume of air. flow is required to release or;funbrake themotor valve. This is advantageousin thatit. requires no veryclose throttling of the valve andatthe same'time permits a very rapid flow of air,*thereby avoiding the necessity of a very critical regu-. lation of the pulsator, and also insuringxagainst clogging of the passage at the. throttle with dirt or dust, which would renderthe pulsator in-v I operative.

A preferred embodiment of the invention is 4 shown in the drawings, in which i; v

Fig. 1 is a longitudinal sectionalview Maepulsator.

Fig. 2 is a section on the line 2--2 ofFig. i Fig. 3 is a section onv the line 33 Of-FigL-I. Fig.4 is a sectionon the line 4-4 of F g; 2. i

at one endby a cap I) and opens at the other end into a casing c, which is divided, by a diaphragm d, into two chambers, preferably of cylindrical shape as shown, one of which, if, I designate as the lower, inner or main diaphragm. chamber and the other of which, a, I designate as the upper, outer or secondary diaphragm chamber.

The inner wall of the pulsator body a is lined.

with a bushing e the end of which abuts against a washer f confined between the closure cap 12 and an annular shoulder on thecbody a.

The body a, and the bushing e are provided with two end air ports g, g, with a central port It communicating with .a vacuum pipe 2, and with two other ports is, is, located between the centralvacuum port. and .the end air ports respectively..and communicating respectively. with nozzlesm, m, adaptedfon connection. with tubes connected with the inflation chambers .of the teat cups (not shown) Such tubes are usuallyof rubber or other flexible material, the. endsof which are slipped over. the nozzles.

.l'he;reciprocablemotor valvepistonn is pro-.

vided with axial end passages o. and a, with a passage p and port. 4 in constant communication with passage. 0,. and with a passage 8 andv party in constant communication with passage r. Passageois in constant communication with the left-hand .end .21. of the piston chamber. Passage 1' is.in.-constant communication with the lower diaphragm chamber t.

The. upper (right-hand). end of. the valve piston 11. extends into. the. lower diaphragm chamber t and, is connected with the diaphragm d by means are yoke .w secured to. the diaphragm, thefree end of. theyoke engaging. an annular groove near.v the...end of the. .valve piston- The yoke w is secured.tothediaphragm by means of a screw :13, a. screw nutz. andnalocknutfic By thi construction, .the..diaphragm and valve piston may have, if desired, limited independent movements, but the, preferred fit :is merely that required for bareclearance. Thestrokeof the piston valve to the. left is limited by yoke 10 contacting bushing e andsuch contact is made before the left-hand end I of the; piston contact with washer f, so that the full-diameterof .such end of thepistomwhen so shifted. is always open to atmospheric pressure, as hereinafter described. The stroke ofthe-pistonto. the right is limited byscrew a: contacting with the end wall of chamber-u.

The two diaphragm chambers are in constant communication bymeans of a passage l0. Within the-passageis a sleeve H. A regulating screw [2- having a needle valve end extends into the sleeve,

whereby the rate of flow of. air between the diaphragm chambersis controlled, thereby controllingtherate of pulsation.

Assume: the piston valve to be shifted to the right, as shown in Fig. 5. Piston chamber then connects with vacuum through port h, passage p,

port q andpassage o.- Nozzle m connects-With" vacuum pipe through port It, passage p and-port k. Nozzlem connectswithair port 9 through passage 3 and port k. Diaphragm chamber t connects. with; air port 9. through passage s, port y and passager. 'Iheright hand end of. the piston valve is thus subjected to atmospheric pressureand the left hand end to vacuum, and the valve would, if unrestrained, immediately shift to the left. However, when, in the movement to the right, the valve connects diaphragm chamber t with the atmosphere diaphragm chamber 11. is (as will be hereinafter described) under a pressure only slightly greater than the half atmospheric pressure in vacuum pipe 1 and due to the area of the diaphragm greatly exceeding the areas of the piston ends the pressure acting to hold the valve greatly exceeds the unbalanced pressure on the valve tending to move it to the left. Due to the unbalanced pressures in the two diaphragm chambers, air flows from chamber t through passage -I0 to chamber a. As soon as the amount of two valve piston ends is one established by the;

valve itself in its movement tothe right.

It may be added that in the central part of; the valve-shifting movement to the left, the ports. 9, g and hare closed. But air continues to flow. from the chamber t to the chamber u, although very slowly due to the pressures being; nearly balanced at the beginning of this shift, thus further reducing the resistance to movement toward the left so that the movement continues even though there is no increase of the positive forces tending to cause movement. To be quite exact, it should be pointed out that at the beginning of this shift.

the inflation spaces of the two teat cups that are connected with nipple m are under atmospheric pressure, while the inflation spaces of the two teat cups that are connected .with nipplem' are under vacuum. The two. teat cups and their v tube connections to nipples m and m act as air reservoirs which, during. the movement of. the piston across center, maintain substantially the same atmospheric pressure in chamber t and substantially the samevacuum in valve chamber 12 that/exists therein at the beginning of the shift. After the slight movement beyond center required to open. port it and connect chamber t with vacuum, the movement of the valve to the left is quickly completed, since at this time chamber u is undernearly atmospheric pressure and chamber t connects (through passage 1, port 3;, passage 8 and port h)- with vacuum, so that the pressure required to complete the movement of the valve to the left and hold it there greatly exceeds the pressure which, by the opening of port g, is now (through passage 3), port q and passageo) established in valve chamber 22.

At the same time the above connections are established, nozzle m (communicating with one pair of teat cups) connects with air port g through port It and passage p and nozzle m (communicating with the other pair of teat cups) connects with vacuum pipe 1' through port h, passage 8 and port It. Since the left hand end of the piston valve is thus subjected to atmospheric pressure and the right hand end to vacuum the valve would, if unrestrained, immediately shift to the right. However when, in the described movement of the valve to the left the valve connects diaestablished diiferentialpressure on the valve tend 'ing to move it to the-right; but air new flows from be had by reference to the-following table:

to chamber it, gradually reducing the resistance to movement to the right while the air reservoirs in the teat cups, as hereinbefore explained, maintain the established vacuum in chamber t and the established atmospheric pressure in valve cham-. her 1) until the piston moves sufficiently beyond center to open port g and connect chamber t with the atmosphere, the movement of thevalve to the right being then quickly completed due to the differential pressures on the large area diaphragm greatly exceeding the'atmospheric pressure on the small area in the valve chamber 12. V

The action of the diaphragm not only prevents the immediate return of the valve after it has completed its shift in either direction, but also, after the valve has, in either stroke, passed a distance beyond center sufficient to reverse, as described, all the pneumatic connections,the sudden unbalancing of the opposing pressures on the diaphragm-insures the quick completion of the stroke of the valve.

A clearer understanding of the operation may ment to the rightthe ports g, g and h are closed, but air continues to flow slowly from chamber it ment ofthe piston to the right greatly exceeds 5 thattending to cause such shift and a large volume of air must flow from chamberu to chamber t before the pressure tending to shift th piston to the right overcomes the opposing pressure. The numbers in the fourth horizontal column indicate the pressures that must be established to shift the pistonto the right.

the diaphragm, as shown in Fig. 7. In this modification the areas of the opposing faces of the diaphragm are different to the extent of the crosssectional area of the valve piston, and the effective absolute pressure on the right hand end of 1 the valve piston is the absolute pressure on the equal to the cross-sectional area of the valve piston. In such a modification the residual thrust numbers are the same as inthe above table. The two constructions are thereforeequivalents.

struction, if the pulsator is positioned vertically:

the weight. of the valve will cause it to drop so that, when the nozzle is connected. with vacuum,

the pneumaticrconnections necessary tov start the operation will bemade. If, however, the pulsator Pressure in operating chambers t, u and 12 [Absolute pressures are used this ta le. Atmospheric pressure=l4.70 pounds per square inch] Pressure per square inch 7 Left thrust Right thrust i ii ig Piston v 7 moves a p t u t it Total v it Total Left Right 7 as 14. 7o 7. s9- 2. 21 Y 16. 36- 1s. 57- 1. 11 3o. 51 31.62 13. 05+ No, 7 35 I 14. 7O 14. 16+ 1 2. 21 29. 41+ 31. 62+ 1. 11 30. 51 31, 63 Left, 14. 70 7. 35 14. 16+ 1. 11 -29. 41+ 30. 52+ 2. 21. 15. 26 17.47 13. 05+ No, 14. 70 7. 35 7. 89- 1. 11 16. 36 17. 47 21 c 15. 26 17. 47 0-]- Right.

It is assumed in the above tablethat the atmospheric pressure is 14.7 pounds to the square inch and that the vacuum is equal to half atmospheric pressure, or 7 .35 pounds to the square inch. The numbers in the first'three ver-' tical columns show pressures to the square inchin piston chamber 22 and diaphragm chambers t and u. The figures in the next six vertical c015 umns indicate pounds (or-other units) of absolute pressure in these chambers, giving proper value to the relative pressure areas of'the diaphragm faces and the ends of the'piston. V

The numbers inthe first horizontal column of numbers indicate pressures when the piston has completed its'st'roke to the right, at which time air at full atmospheric pressure is admittedto chamber t, while piston chamber v'is connected with vacuum. At this time the pressure opposing movement of the piston to the left greatly exceeds that tending large volume 'of air must flow from chamber 13 to chamber-"u before the pressures tending to shift the'piston to theleft overcome the opposing pressure. The numbers in the second horizontal column' indicate the pressures that must be established to shift the piston to the left. As soon as the shift of the piston to, the left is'completed, chamber' tis connected 'with the atmosphere, the.

to cause such shift and a is positioned horizontally, the valve-ma assume a dead. center position, at which position the pneumatic connections necessary to operation would not bemade and the pulsator would not start to operate. Even during operation conditions may arise which would interrupt'the pneumatic connections and cause the pulsator to asobjections to positioning the pulsator vertically, one or which is that when the pulsator is mounted on a milk pail, the handle will have to to start. the pulsator. In this figure the valve is shown to the left of dead center so that Vacuum' port It has just barely started to open to connect diaphragm'chamber twith vacuum and air port 9' has just barely started to connect valve chamber 12 with the atmosphere.

This arrangement requires that the diaphragm shall flex from its normal position further to the rightthan to the left and this inturn requires numbers in the third horizontal colum indicat' ing pressures when theshift to the left is com-ff pleted. 'At this time the pressure opposing move- The operation would not be essentially different if the valve pistons were connected directly to right hand face of the diaphragm over an area I It is entirely practicable to so construct the sume a dead center position. There are certain tion, the valve is sufficiently Off dead center to 7 just make the pneumatic connections necessaryly) one half the sum of the diameter of the'dia quate to reverse the net pneumatic forceifseez that-the effective pressure acting to shift the;dia.-.-. phragm to the-right shallbe greater: than. thatrto shift it tothe left. This requirement-ris-satisevfied by constructing the diaphragm, as shown in. the figures,-so that it comprises a centralrflexiblew shown in Fig. 6. Therefore,in the movement-of and elastic disc d secured circumferentially,,to.-. the cylindrical'wall ofthe casing and p13$6Sw|5ri and I! (which should be round if thechambers t and u are cylindrical) of the metal or other rigid, 1'

material and of different diameters applied to the: opposite sides of the disc d and secured preferably; only at their centers to thecenter of the discyor-i- (at any rate) that the disc shall not be secured? to the larger plate outside the'circumference of:

to the right than .to' the left, it-is clear-that when the valve and. diaphragm are in the right 'hand position shown in Fig. 5, it is under a higher tension than when it is in the left hand position the .valveto the left, a relatively strong tension .of the diaphragm tending to move it to the left is opposed by a relatively strong pneumatic force acting directly thereon; while in the movement --.'10 of the valve to the right a relatively weak tension of the diaphragm tending to move it to the right isopposed by a relatively weak pneumatic force acting directly thereon.

It is necessary that, at the end of both strokes the smallerplate. When the pressureisacting:.r 5 of the valve, the difference between the pneu to hold-the diaphragm to-theright, 'asshown Fi 5, the part of the flexible disc 0, outsidethe. plate I6 is held againsttheplate IT by the'higher;

pressure in-chamber "t, theeffective area of'the" disc and'plate being the area of a circle the-diameter of which is-equal to-(approximatelylone; half the sum of thediameter of diaphragm d and the diameter of plate l1.= When the pressureis':

acting to hold the diaphragmto the left, asshown-= in Fig, 6,'the part of thefiexible disc it outside. the plate I6 is held away from plate l1 by the higher pressurein chamber. u, the effective area:- of the disc andplate being the area of a 'circle': the diameter of which is equal to (approximatephragm d and the diameter :of plate I6.

If we assume that the valve has shifted to their" right and that thereafter a certain volumezofair has flowed from chamber '7. to chamber/wade table on page 3) and start movement of the valve to the left, the pressure in chamber t is still higher than in chamber a (see said table) and continues to hold the diaphragm in the position relative to plates l6 and [1 shown in Fig. 5 untilthe valve has moved sufi'icientlybeyond dead cen-.. ter to open air port g to chamber v and vacuum port It to chamber 25.

If we assume that the valve has shifted-ito the has moved sufficiently beyond dead-center to open mentawayfrom .opposite positions, by differential pneumatic forces, acting directly on the dia-. phragm, resisting such tensions.

A simpler way of providing means to start the pulsatorif it is on dead center is to provide a pin M (slidable in .the cap b and washer-j) provided with'a head adapted, when the pin is pushed inby hand, to engage the end of. the piston and shift it to or toward its right-hand position. When the pressure on the-pin is released-it. is re-.

tracted by a spring .l5 and performs no function in the operation of the pulsator. It may happen, however, that in freezing weather, due to moisture within the pulsatonthe pistonwill be frozen to the valve chamber. Therefore the com mercial pulsator is provided with this springpin by means of which the pulsator may be readily freed. 7

.By providing the pulsator with such a spring pressed pin, the described special construction of 45 the diaphragm .to insure. .that the: pulsator will? air port 9 to chamber 1. andyacuum port it to chamberv. While, duringboth oftheseopposite movements, the difference between the pneumatic pressures in thetwo chambers is the.-same,= the pneumatic pressure in chamber 15 resisting-movement of the diaphragm-from the right end. posi-.-

tion is operative on a greater area of the dia-,. phragm during the movement of the valve-to the.-: left (until the connectionstovacuum and. atmos phere are reversed) than duringthemovement of the valve to the right; while the pneumatic pressure in chamber u resisting movement of the diaphragm from the left end position is opera-i! tive on a smaller area of the diaphragm-.dur-

ing the movement of the valve to theright-(untit 1 the connections to vacuum and atmosphereare reversed) than:during..the movement ofthe'valve to the left. Since, asraboveaexplainedpthe=dia--.. phragm-xfiexes :rfromsits'r normal-position furthers never assume a dead center position is .unneces-i'- sary and itis not intended to restrict the claims thereto except as specifically claimed. Even with the use of the described special diaphragm'con struction, the spring-pin starter may be" re tained as an additional means whereby the pulsa tion may be positively moved to an end position. Conversely, even when the spring-pin starter is provided, it is preferable to employ the special construction of diaphragm described in "order to insure against the piston valve assuming'a dead center during operation in case of "temporary? interruption of the vacuum.

While in the foregoing description I have-dc" scribed those characteristics of the invention:

which apply to the specific embodimentof the vention illustrated and described, it 'shouldinotj be understood thatall such characteristics, are

each' strokexof: the: pulsatontoi make. connections.

' with sources of high and low pressures adapted to establish comparatively high differential pneumatic pressures on said opposing pressure surfaces and thus prevent immediate reversal of theuvalve, and'a conduit through which, after said differential pressures are established, air-is adapted'to now from one side of the diaphragm. to the other until the pneumatic pressures on opposing pres- 'sure surfaces are balanced and then reversed,

thereby eifecting the reversal of the pulsator.

2. An automatic pulsator in accordance with claim 1 comprising also two ports in the valve chamber adapted for connection with two different pairs of-teat cups and means operable on one stroke of the valve'to connect one port with the source of high pressure and the other port with the source of low pressure and on the other stroke of the valve toreverse said connections,

said connections being established substantially simultaneously with said establishment of high differential pneumatic pressures on said opposing pressure surfaces. 7 3. An automatic pneumatic pulsator having openings connect-able with sources of high and low pressure and comprising a reciprocable valve; a diaphragm of relatively large area connected thereto, teat cup connections, means operative on to be moved by the differential pressures operative thereon, and means operable in the other direction of movement of the valve to reverse the pneumatic connections to its opposite ends and thereby tend to reverse it and to connect the first named diaphragm chamber with the source of low pressure, thereby holding the valve from reversing until by the flow of air through said-passage in theopposite direction the pressures in said chambers are again sonearly equalized as to enable the valve to be reversed by the differential pressures operative thereon.

6. An automatic pneumatic puls-ator for milking machines comprising a cylindrical piston chamber, a diaphragm of relatively large area, 'a

, piston valve connected tothe diaphragm and reciprocable in the piston chamber, the piston chamber having two ports adapted for connection with two pairs of teat cups, means'operable in the reciprocation of the pistonvalve in one direction to connect witha source of ,low pressureone of said ports and the end of the valve chamber remote from thediaphragm and to connect with a source of high pressure the other of said ports the-movement of the valve in either direction to reverse the pneumatic connections to the teat cups'and to immediately establish pneumatic connections to the valve tending to reverse it and differential'pneumatic pressures on opposed faces of the diaphragm effective to hold the valve in the position to which it is moved, and a conduit providing a restricted passage'through which air is adapted to flow from one side of the diaphragm to the'other until the pressures on opposite sides of the diaphragm so nearly balance that the pneumatic pressure on the valve i ef-v fective to reverse it. a

and one side of the diaphragm .while the other side of the diaphragm is under lowpressure, I thereby holding the piston valve from moving in the'opposite direction, a conduit connecting 0D- posite sides of the diaphragm through which air flows until the pressures on opposite sides of the diaphragm are nearly balanced, thereby enabling the valve to move in the last named direction, and means operable in the movement of thevalve in the last named direction to connect with a source of high pressure the first named port and the end i of the valve chamber remote from-the diaphragm and to connect with a source of low pressure the second named port andthe first named side of the diaphragm while the'otherside of the dieither direction to reverse the pneumatic connections to the teat cups,to establish opposing differential pneumatic pressures on the valve tending to reverse it, and to create similar differential pneumatic pressures in the twodiaphragm chambers effective to hold the valve from reversal, and

a restricted passage connecting the two 'diaphragm chambers through which air is adapted to flow until the pressures therein are so nearly balanced that the said differential pressures on" 1 the valve are effective to reverse it.

5. An automatic pneumatic pulsator for milking machines comprising a valve chamber, a motor valve reciprocable therein, a diaphragm of comparatively large areaconnected to the valve and formingon opposite sides thereof two chamhere, means operable in one direction of move-.'

ment ofthe valve to connect its opposite ends with high andlow pressures tending to move it in the opposite direction and to connect one of the diaphragm chambers with'the source of high pressure while the other chamber-is under low pres-sure, thereby holding the valve-from so moving, there being a restricted passage connecting the two chambers through which air is adapted aphragm is under high pressure, thereby holding the valve from moving in the first named direc- 171011311 thereupon flowing through said conduit until the pressures on opposite sides of the diaphragm are again nearly balanced,-thereby'enabling the valve to move inthe first named direction, the second named side of the diaphragm being closed from communication with sources of high and low pressure except through said'conduit. I I

'7. An automatic pneumatic pulsator, for milking machines comprising a valve chamber having two ports adapted for connection with twopairs of teat cups and also ports communicating with atmosphere and vacuum, a motor valve recipro cable therein and adapted in its movement in one direction to connect one'end of'the' valve and one of the teat cup ports with vacuum and. the other end of the valve and the other teat cup port with the atmosphere and adaptedfin its movement in the other direction to reversesaid I connections, whereby the'valve acts as a motor- 'to effect its own reciprocation, a diaphragm of comparatively large area connected with the valve, means operative in opposite strokes "of the valve to provide free communicationbetween one side of the diaphragmand atmosphere and vacuum respectively, and an air conduit connecting opposite sides ofthediaphragm, whereby at each end stroke of thevalve high differential pressures are immediately established on opposite sides of the diaphragm to thereby hold the valve from reversing itself. until-flow of air through said conto flow until thepressures in the two chambers are so nearly equalizedas to enable the valve duit so nearly balances the said opposing'pre'ssures on the diaphragm that the differential pressure on the valve is effective to: reverse it.

-' 8: In an 'automatic pneumatic pulsator I for -milking machines, a, cylindrical-valve chamber,

a piston' -valvereciprocable "therein, ports and passageswhereby when the piston is at either end of its stroke thenear end will have unre-, strictedconnection-with a maximum high pressure and the other end unrestricted-connection with a minimum low pressure, a diaphragm having an area multiple times that of the piston and havingits sideradjacent the-pistonalways ex -posed to the same pressure as'the adjacent end of the piston and a-passage whereby restricted communication is alwaysw open-from the space "directly adjacent one side of the diaphragm to the space' directly adjacent the other sidethereof.

9. Inan automatic pulsator for'milking-machines; a cylindrical valve chamber, a .valve piston re'ciprocable therein, ports and passages so located that when the'pistorr reaches either end 7 -of its stroke the 'advanc'ed" end will be connected with a'sourceof high 'pressure and the trailing end with a source of low pressure; such difierential pressures therebytending to immediately reto the differential pneumatic pressures on opposite ends of the piston and hold s'aid pistonfrom reversal and then 1 to gradually reduce said un- I balanced pressures until they: become inferior to the" differential pneumatic pressures oniopposite ends'of "the-piston, thereby eifecting a reversal "of the-piston.

'109 An automatic pulsator for milking machines t comprising pneumatically :reciprocable means having opposing pneumatic --ma-jor.' pressure areas .and opposing minor: pressure-areas,

1 said means including a pneumatically reciprocable valve, means; including 1 ports and passages, op erable -in'- one stroke 'of thevalve to connectone 5 major =pressure area and-one opposing -minor "pressure area'with a-source of highpressure and 'thg otherjmihor area with a source of :lowpres- 7 :-when the nearly equal pressuresron-opposite sides f the diaphragm are low.

12. Alpulsator comprising a casing anda diaphragm dividing the same into a main chamber and a secondary chamber, means allowing restricted air flow between said chambers, a piston chamber, a piston therein connectedwith said diaphragm and having a pressure facej'at one end opening into said'main chamber and a-pressure face at the other endopeninginto a pressure :chamber of small area relative to that of the, diaphragm, andmeans operable, in one'stroke of the piston, to connect the main chamber and pressure-chamber with high and lowpressures respectivelyand in the other stroke of the, piston to reverse said connections, said last named connections being so relatively unrestricted as to imnmediately establish said pressures, the piston kthereby' tending to reverse itself immediately after *each stroke but: being held from reversal until said'restricted air flow between said chambers so nearly balances the difierential pressures on I the diaphragm that the differential pressures on 'Jthe opposite pressure faces of the valve become 5 effective toreifect said reversal.

13. A pulsator comprising passages connectable-with sources of high and low pressures, a casingjaand a diaphragm therein dividing the same into a main'cham'ber and a secondary Jo chamber, means allowing restrictedfiowof air between said chambers, the secondary chamber being sealed from communication with said sources of; high and low presures except through themainchamberas above specified, a piston chamber, apiston therein connected with said diaphragmpand having apressure face at one end 5 opening into said main chamber and a pressure face at the other end opening into a,

pressure chamber of small area' relativeto that of the diaphragm, and means operable, in one stroke ,-of the piston, to connect the main chamber and pressure chamber with'high and "low pressures respectively and in'the other stroke of the" piston to reverse saidconnections, the said last named connecting means allowing such free'flowofair that at the completion of each stroke said-pressures are quickly vestablished.

14. A pulsator comprising a casing and a diasure and in the other stroke of the valve: to reverse saidconnections; and .axrestricted passage 3 through which aftervonetstrokeoftthe valve air phragmdividing the same into a main chamber 9, and a secondary chamber, a-piston chamber, a piston therein connected-with said diaphragm and 'fiows' from the dastnamed major pressure area tothe other 'majorwpressures areaauntilt'both are n' yi q h h p suresaflndithroug other end opening into a'pressure chamber of small area relative'to that of the diaphragm,

rwhich ta-fterjlthe otherstr'oke ofvthe: valve air '1 fiowsrfrom': thesecondmajon pressure-area to the first majorapressure area: until-.;both are.;under nearlyqequal low; pressures, thereby in eachcase causing :the high pressure-on one minorrarea to reverse [the valve.

11..An automatic pulsator."for;::mi'lking mahaving apressure face at one end opening into said main chamber and a pressure face at the and means operable, in one stroke of the piston, to connectthe main chamber and pressure chamber with high and low pressures respectively and in the other stroke of the piston to reverse said connections, and means allowing restricted flow of air between said diaphragm chambers whereby after the first stroke of the piston the pressurerin the secondary chamber is increased by :said air flow until it so nearly balances the. high pressure in the main chamber that the high pressure on theface of the piston opening into the "main chamber effects the second named stroke of the piston and whereby after thesecond named stroke of the piston the pressure in the secondary chamber is decreased by said air flow until it so nearly a balances the low pressure in the main I :chamber that the high pressure on the face of the piston opening into the small chamber eifects :thefirstnamed stroke of the piston.

15.- A pulsator comprising passages connectable with sources of high and low pressure, 2', diaphragm casing of relatively large area and a piston chamber of relatively small area, a diaphragm dividing the easing into a main chamber and a secondary chamber, means providing a restricted passage between the chambers, the secondary chamber being sealed from communication with said sources of high and low pressure except through said main. chamber, a third e the piston to reverse said connections, whereby at opposite strokes of the piston the pressure .in the main chamber is immediately respectively raised to maximum and reduced to minimum, while between shifts the flow of air through said restricted passage continues until the opposing pressures on the diaphragm so nearly balance as to permit the shift of the piston, one shift being thereby effected when the pressures on both sides of the diaphragm are high and the other shift being effected when the pressures on both sides of the diaphragm are low.

16. A pulsator comprising passages connectable with sources of high and low pressure, a diaphragmcasing of relatively large area and a piston chamber of relatively small area, a diaphragm dividing the casing into a main chamber and a secondary chamber, means providing a restricted passage between the chambers, the

secondary chamber being sealed from communication with said sources of high and low pressure except through said main chamber, a third, chamber remote from the diaphragm, a

valve piston connected with said diaphragm at one end, the other end being constantly exposed to the pressure in the third chamber, and means operable in one shift of the piston to afford unrestricted communication between the source of high pressure and the main diaphragm chamber and between the source of low pressure and the third'chamber and in the other shift of the piston to reverse said connections, whereby after the shift of the piston in one direction the pressure in the main chamber is continuously at its maximum while the pressure in the secondary chamber rises until it nearly reaches the maximum pressure in the main chamber, whereupon the piston shifts in the opposite direction and whereby after the shift of the piston in the opposite direction the pressure in the main chamber is continuously at its minimum while the pressure in the secondary chamber falls until it nearly reaches the minimum pressure in the main chamber, whereupon the piston shifts in the first named direction.

17. A pulsator comprising acasing and a diaphragm dividing the same into a main chamber and a secondary chamber, a motor valve piston in the piston chamber one end of which extends into the main chamber and is connected with the diaphragm and has at that end a pressure face exposed to the pneumatic pressure in the main chamber, a third chamber at the other end of the piston, which other end has a pressure face subject to the pneumatic pressure in said third chamber,.the diaphragm being of much larger area than the piston faces, means operable in one stroke of the piston to provide unrestricted communication between a source of high pressure and said main chamber while the secondary chamber is under low pressure and unrestricted communication between asource of low pressure and said third chamber, the piston I thereby tending to immediately reverse itself but being held from reversal by the high pressure inthe main chamber, means providing a restricted air passage between said main and secondary chambers through which air flows from the main chamber to the secondary chamber until the pressure in the secondary chamber nearly equals the high pressure in the main chamber, whereupon the superior pressure on the pressure face of the piston adjacent the diaphragm becomes effective to reverse it, and means operable in said reversal stroke of the piston to provide unrestricted communication between the source of low pressure and said main chamber and unrestricted communication between the source of high pressure and said third chamber, the piston thereby tending to immediately reverse itself but being held from reversal by the high pressure in the secondary chamber, air thereupon flowing through said restricted passage from the secondary chamber to the main chamber until the pressure in the secondary chamber is reduced to nearly that of the low pressure in the main chamber, whereupon the superior pressure on the pressure face of the piston remote from the diaphragm becomes effective to reverse the piston.

18. An automatic pulsator for milking machines comprising pneumatically 'reciprocable means having opposing pneumatic pressure sur faces, saidmeans including a pneumatically reciprocable ,valve, means, including ports and passages connectible with sources of high and low pressure and adapted during the movement of the valve in one direction to connect certain of said opposing pressure surfaces with sources of high and low pressure respectively and thereby establish high diflerential pneumatic pressure on opposingpressure surfaces adapted to hold the valve at the end of its'stroke and during the movement of the valve in; the opposite direction to reverse said pneumatic connections and hold the valve at the end of its stroke, a continuously open air flow passage directly between two only of said opposing pressure surfaces one of which surfaces is continuously closed from communicationwith said sources of high and low pressure except through said air flow passage while the other is connectible with said sources of high and low pressure respectively at opposite end positions of the valve, the new of air through the last named passage when the valve is at either end of its stroke effecting first agradual reduction and then a momentary balancing of said opposing pneumatic pressures and then a reversalthereof to thereby establish low differ ential pneumatic pressure on opposing surfaces effective to move the valve in the opposite direction until the connections, to the first named ports and passages are reversed.

19. In an automatic pulsator for milking machines comprising a valve chamber, a valve reciprocable therein and ports and passages ponnectible respectively with sources of high and low pressures whereby, when said connections are established, the near end of the valve, at

either end of its 'stroke, will connect with a source of high pneumatic pressure while the other end will connect-w ith a source of low pneumatic pressure, thereby effecting reciprocation of-the valve: the herein described improvement by which the valve-ismade self starting,'which comprises a diaphragm so securedtothe valve that, .when not under tension andbeforesaid diiferential .pneumatic connections are established itlwill hold the valve off center and in such connection with said ports and passages that when said differential connections are established the valve will start operation, there being an air-flow passage between opposite sides ofvthe diaphragm tending to equalize the pressures thereon, one side of the diaphragm communicating with the ports and passages communicating with one en of the valve, said diaphragm thereby being subjected, at either end position of the valve, to a pneumaticforce resisting, but not preventing, movement of the valve when the pressures on opposite sides of ...the diaphragm nearly reach equilibrium; said diaphragm comprising a flexible ,member and rigid reinforcing members of difierent areas applied to opposite sides of. thediaphragm, thereby enabling equal pneumatic pressures to be opera- -tive on diiferentareas of thediaphra-gm during movements of the valvevfrom opposite end ,positions, said equal pneumatic pressures thus opposing a greater resistance to movement of the valve in one directionthan inthe other direction to compensatefor thegreater tension of the diaphragm in one of such, movements than in the other of i said, movements.

20. An automatic milking machine pulsator comprising a valve chamber, a motor valve reciprocable therein, a diaphragm connectedand movable with said .valve, means, including ports and passages, adapted, during one stroke of the valve to connect one end of the valve and one side of the diaphragm with a relatively high pneumatic pressure and the other end of the valve with a relatively low pneumatic pressure and in the opposite stroke of the valve to reverse said connections, there being a passage between opposite sides of the diaphragm through which, after each stroke of the valve, air flows, the pneumatic pressure on one side of the diaphragm resisting the pressure tending to move the valve in one direction and the pneumatic pressure .on the other side of the diaphragm resisting the pressure tending to move the valve in the other direction, said resisting pressures being effective to prevent movement of the valve until by flow of air through the last named passage the pressures approach equality, said diaphragm being so located relative to the valve that when the diaphragm is in its intermediate position and not under tension the valve is oiT center and in position to make one of the above specified pneumatic connections to the valve and diaphragm, said diaphragm comprising a flexible member and rigid reinforcing members of different areas applied to opposite sides of the flexible member, whereby thepneumatic pressure operative upon the diaphragm to resist movement of the valve is higher when the valve, at one end of its stroke, imposes a relatively high tension on the diaphragm than when the valve, at the other end of its stroke, imposes a relatively low tension thereon.

21. An automatic pulsator for milking ma- ,chines comprising pneumatically reciprocable means movable in unison and having opposing pressure faces, said means comprising only a single pneumatically reciprocable valve, ports, continuously connected with sources of relatively high and low pneumatic pressure respectively,

. passagesadapted. in and by the movement OffthB one of such sources as to establish difi'erential pressures on all said pressure faces eifective to hold the valve in the end position to which it is moved, there being a passage continuously directly connecting said excepted pressure face with a space adjacent an opposed pressure face and not, otherwise than through said space, connecting it with either of saidpressure sources, through which last named passage, after movements of the valve in opposite directions, air flows in respectively opposite directions between said continuously connected pressure faces until in one end position of the valve the pressure .on said excepted pressure face is sufficiently high, while until in the other end position of the valve the pressures on the said. excepted pressure face is sufficiently low, to establish differential pressures on all said pressure faces reflective to reverse the valve.

22. An automatic pulsator for milking imachines comprising a single pneumatically reciproarea with a source of low pressure, and in the other stroke of the valve to connect the last named major pressure area with a source of low pressure and said minor pressure area with a source of high pressure, each of said connections establishing such differential pressures on said ,opposing major pressure faces as to holdthe-valve from movement, a restricted passage through i which after one stroke of the valve air flows from one major pressure area to the other untilboth areunder nearly equal high pressures and through which after the other stroke of the valveair flows in the opposite direction until both major areas are undernearly equal low pressures, whereby, after each flow of air as aforesaid the tendency of the valve to shift fromone position to the other becomes effective.

23. An automatic pneumatic pulsator for milking machines comprising a single system of elements reciprocable in unison and including a valve with opposed minor pressure areas and a member with opposed major pressure areas, means operable in either stroke of the valve to so connect the minor areas with sources of relatively high and low pressure as to cause a force tending to reverse the movement of the valve and to simultaneously so connect one of the major pressure areas as to oppose movement of the valve, there being a restricted passage adapted to allow flow from the high to the low pressure side of said member until the opposing pressures thereon are so nearly equalized as to permit reversal of the valve by the forces on the minor areas.

24:. The herein described method of operating a milking machine pulsator having only one reciprocating valve member which comprisesv subjecting said valve member in one end position to opposing relatively high and low pneumatic presproviding restricted flow between the same pressure zones above specified until opposing pressures are barely reversed, thereby returning said valve member toward the first named end position and 15 thereafter quickly increasing the last established low pressure to high pressure to thereby establish the differential pressures first above specified,"

establishing the flow of air, required to effect said gradual and sudden reversals of pressure, partly by'flow of air between the zones of opposing pressures above specified and partly by flow of. air

to one of said pressure zones from a source of high pressure and partly by flow of air from the last named pressure zone to a source of low pressure, and controlling said flow of air solely by said valve member in its shift from one end position to the other.

CYRUS OWARD HAPGOOD.

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