US2138921A - Milking machine pulsator - Google Patents

Description

Dec. 6, 1938. J. 1.. HULBERT MILKING MACHINE PULSATOR Filed April 20, 1955 //A yaw- IIIIIII NW VN mm f w M w M "a m it W W; b o n a Q .3 A8 2 m. a t -I- E w g m "N 35 o g 6 w n Patented Dec. 6, 1938 murmc MACHINE rursa'roa John L. Hnlbert, Poughkeepoie, N. Y.. aooignor to The De Laval Separator Company, New York, N. Y., a corporation of New Jersey Application April 20, 1935, Serial No. 17,385

9 Claims.

My invention is an improvement in automatic pneumatically operated devices, commonly called pulsators, for producing and controlling the pneumatic waves or pulsations in the teat cups of milking machines.

The object of my invention is to provide a pulsator that is simple, inexpensive, positive and reliable in operation, with which there will be little variation in speed and with which the pul- 1o sations will be balanced, that is, the duration of the high pressure portion of the wave will be the same as that of the low pressure portion of the wave.

The reduction of variation in speed is obtained by complete elimination of friction as a control and reduction of other friction to a minimum. The equality of time for high and low pressure portions of the wave is obtained by making all parts, both stationary and movable, symmetrical about their center 0! length so that the forces that cause movement in one direction are equal to those that cause movement in the other direction.

' In Patent No. 1,885,110, issued to me November 85 l, 1932, I disclose a pulsator construction in which, because the forces that cause operation in one direction are equal to those that cause operation in the other direction, the pulsation waves will be balanced. This pulsator,however,

'0 has piston valves which necessarily have very small clearances and hence are liable to be made sticky by fine dust, with some resultant danger of stoppage. Also, wear resulting from use increases the clearances and the leakage past these valves and hence tends to ultimately cause a change in the speed of the pulsator.

In the pulsator of the present invention, all clearances between relatively movable metallic members are so great that there is no danger of clogging or sticking by collections of dirt, and air can flow between them so freely that changes due to wear are negligible.

In the accompanying drawing, which shows an embodiment of my invention:

5 Fig. 1 is a longitudinal section of my pulsator,

on line x:c of Figs. 2 and 3.

Fig. 2 is a cross section on the line 2-2 of Fig. 1.

Fig. 3 is a cross section on the line 3-4 of Figs.

50 1 and 4.

Fig. 4 is a partial cross section on line 4-4 of Fig. 3.

Fig. 5 is a partial cross section, taken on line :r---:: of Figs. 2 and 3, showing a modification 56 of the construction shown in Fig. 1.

In the specific embodiment of my invention shown in the drawing the body consists of -a central piece a, right and left hand intermediate pieces 1;, b, and right and left hand end pieces 0, c, all strung on and heldtogether by a bolt 20 near to the center. Suitable means may be provided, such as dowels (not shown) in one corner, to prevent the parts twisting around the bolt out of alignment. Through the central and the two intermediate pieces there is a bore surrounded by rigid valve seats d, d on the central piece and e, e' on the respective intermediate pieces. In the respective intermediate pieces b, b there are pulsation chambers I, l respectively communicating directly with pulsation nipples (one, 8, of which is shown in Fig. 3) and, through restricted orifice 9, 9', with the spaces inside the end pieces c, c'. The bore in the central piece a is in communication, through ports Ii and I2, with the atmosphere. The central parts of the bores in the intermediate pieces b, b communicate, through ports i2 and I3 respectively, with a chamber It in which a partial vacuum is maintained.

Each of the end pieces c, 0' forms, with part of the space in the adjacent intermediate piece, an air chamber I! or I! having an opening i6 or ii in alignment with the aforementioned bore and around which there is a valve seat I! or H and an annular space I. or it. These air chambers are separated from the bore by flexible non-permeable walls I! or it.

In the bore there reciprocates a loose fitting valve carrier 20 having two grooves that carry flexible poppet valves 2|, 2|. when the carrier 20 is at the left hand end of its stroke, flexible valves 2|, 2| fit against the valve seats e and d respectively, and wall I! is forced against the seat II.

The operation of the pulsator comprising the parts above described is as follows. With the valve carrier 20 in the position shown, atmospheric air will fiow through ports l2-ll and the bore in the central piece past valve seat it into pulsation chamber 1 and, thence through the corresponding nipple 8 toward a teat cup, not shown, and slowly through orifice 9 into the chamber I, wherein it will gradually. raise the pressure against the flexible wall I! pressing against the left end of the valve carrier.

At the same timeiflfilrom chamber it will fiow slowly throull. restricted orifice 9 and from another mcyeub, not shown, through the other nipple into the pulsation chamber 1' and thence, through the bore in the intermediate piece b and the port l3", into the vacuum chamber i4.

With the gradual increase of pressure at the left end and simultaneous decrease of pressure at the right end the resultant force soon changes from one toward the left to one toward the right and the carrier 20 begins to move toward the right. As soon as it makes a slight movement the flexible wall I9 leaves the seat I! and allows air to flow into the annular chamber I8 and so greatly increase the force toward the right that the valve carrier completes its stroke almost instantaneously.

The valve 2| will leave the seat e and be forced against the seat d and the valve 2! will leave the seat d and be forced against the seat e, thus reversing the fiow of air toward and away from the teat cups (not shown) and the air chambers l5 and i5 so that the pressure will gradually decrease in chamber i5 and increase in chamber l5 until the carrier is driven to ward the left and the cycle thus completed.

From the preceding description it will be clear that when the carrier 20 begins a stroke in either direction it is sure to complete it. The control of speed is entirely by the size of the orifices 8 and 9'. By making these with stream-lined ends, I insure that the flow of air shall be across the entire area of the orifice instead of through a relatively small area along the center and thus almost entirely eliminate the deposition of dust, which would otherwise clog the orifice and reduce the flow of air and therefore reduce the speed of the pulsator. This makes the speed very uniform.

While, as stated, there is almost no dust deposition with the use of this form of orifice, it is desirable that any slight dust that may in time deposit should be readily removable. For this reason I prefer to use the construction shown in Fig. 5. In this modification the restricted orifice 9 is turned at right angles to the position shown in Fig. 1 and a wire 25 carried by a plunger 26, constrained by a spring 21, is in alignment with the orifice. If and when dust collects and the pulsator begins to run slowly, the operator can, by pressing a finger on the exposed end of the plunger 26, move it inward and force the wire 25 through the orifice 9 and clean it, and the pulsator will at once resume full speed. The wire is a close fit in the orifice and has its end fiat so as to shear all dust off the walls of the orifice and push it through the orifice instead of packing it against the walls.

Though, as I previously explained. the valve carrier, while in operation, will always complete a stroke once started, there is danger that, when being carried around while not in operation, the valve carrier may be jarred to the center of its stroke and remain there with all valves open so that air can blow through without causing any movement. To provide for this contingency I have devised the starter shown in Figs. 3 and 4. The wall separating the left hand intermediate piece b from the central piece a has a port 20 surrounded by a shallow depression 28 from which another port 22 leads to the vacuum chamber l4. On the adjacent wall of the central piece a is a flange 23 that retains a flexible valve 24 close to the shallow depression. when the chamber [4 is first connected to a source of vacuum it is connected directly to chamber I! through port 22, depression 28 and port 29 and immediately partially exhausts this chamber. As the chamber I5 is full of air at atmospheric pressure, the valve carrier is forced to the left, ready to begin operation as previously described. With the increase of vacuum in chambers i4 and I5 and in the depression 28, atmospheric pressure on the other side of flexible valve 24 soon forces it down and closes both ports 29 and 22, after which the pulsator operates as if there were no starter on it. If, for any cause. the vacuum at the pulsator becomes so low that it stops, the tension of .the valve 24 will cause it to open and create the condition that will make it start when the vacuum increases to an operating value.

Because the forces that cause movement in one direction are equal to those to cause movement in the other direction and because the same control orifices control the flow of air to produce these forces, the times of pause at both ends of the stroke will be the same and the high and low pressure waves will have equal time intervals.

Because the valve carrier 20 has a liberal clearance in the bore in which it reciprocates,

it will not be clogged by dust, friction will always be negligible and wear will cause no changes in speed.

What I claim and desire to protect by Letters Patent is:

1. In a milking machine pulsator, the combination of a body member having two pairs of spaced apart valve seats, a valve carrying member reciprocable in the body member, poppet valves carried by the carrier member, one for each pair of valve seats, air passages, sources of high and low pressure, and air chambers at oppoite ends of said carrier and adapted, at either end position of the carrier, to be connected, by said valves, through said passages, one with the source of high pressure and the other with the source of low pressure to thereby effect the shift of the carrier toward its other end position, sad body member and valve seats being symmetrical about the center of length of the body member and said poppet valves being symmetrical about the center of length of the valve carrier.

2. In a milking machine pulsator, the combination of a body member having two pairs of rigid spaced apart valve seats, a valve-carrying member reciprocable therein, flexible poppet valves carried thereby, one for each pair of valve seats, air passages, sources of high and low pressures, and air chambers at opposite ends of said carrier and adapted, in either end position of the carrier, to be connected, by said valves through said air passages, one with the source of high pressure and the other with the source of low pressure to thereby effect the shift of the carrier toward its other end position, said body member and valve seats being symmetrical about the center of length of the body member and said poppet valves being symmetrical about the center of length of the valve carrier.

3. In a milking machine pulsator, the combination of a central piece, end pieces and intermediate pieces, said central and intermediate pieces providing a bore and two pairs of spaced apart valve seats on opposite sides of the center of said bore, a carrier reciprocable in said bore, poppet valves on the carrier on opposite sides of the center thereof, each adapted to seat alternately on the two valve seats of the corre sponding pair, a source of high pressure communicating with the space in the bore between the inner faces of said valves, a source of low pressure communicating with the spaces in the bore at the outer faces of said valves, and air passages communicating with the spaces between the respective pairs of valve seats and with the respective air chambers, said carrier being reciprocable by unbalancing of air pressures in the two end chambers, said pieces and valve seats being symmetrical about the center of length of said bore, and said valve carrier and valves being symmetrical about the center of length of said valve carrier.

4. In a milking machine pulsator, the combination of a central piece, end pieces and intermediate pieces, said end pieces providing end air chambers, said central and intermediate pieces providing a bore and two pairs of spaced apart valve seats on opposite sides of the center of said bore, a carrier reciprocable in said bore, poppet valves on the carrier on opposite sides of the center thereof, each adapted to seat alternately on the two valve seats of the corresponding pair, a source of high pressure communicating with the space in the bore between the inner faces of said valves, a source of low pressure communicating with the spaces in the bore at .the outer faces of said valves, air passages communicating with the spaces between the respective pairs of value seats and with the respective air chambers, and flexible valve walls, at the ends of said bore, separating said bore from the respective end chambers and alternately engageable by the ends of the carrier in the latters reciprocation, said carrier being reciprocable by unbalancing of air pressure in the two end chambers, each flexible wall being movable, by the building up of pressure in the corresponding air chamber, to start the valve carrier to shift from one end position and presenting, after the start of said shift, an enlarged area to effect a rapid completion of the shift.

5. In a milking machine pulsator, the combination with a body having a bore with poppetvalve seats, a member reciprocable within said bore, poppet valves carried by said member and adapted. to cooperate with said seats, air chambers at opposite ends of the bore, flexible none permeable walls closing the bore from the respective air chambers and adapted to press against the adjacent end of said member, sources of high and low pressures, and passages adapted when the member is at either end of the bore to connect the near chamber with the source of high pressure and the far chamber with the source of low pressure, each of said passages having a constricted portion.

6. In a milking machine pulsator, the combination of a body having a bore with poppet-valve seats, a member reciprocable within said bore,

Search Rec poppet valves carried by said member and adapted to cooperate with said seats, air chambers at opposite ends of the bore, flexible non-permeable walls closing the bore from the respective air chambers and adapted to press against the adjacent end of said member, sources of high and low pressures, and passages adapted, when the member is at either end of the bore, to connect the near chamber with the source of high pressure and the far chamber with the source of low pressure, each of said passages having a restricted portion with stream-lined ends to promote flow through the full area of the restricted portion.

'7. In a milking machine pulsator, in combination, a body having a bore with poppet-valve seats therearound, an air chamber at each end of said bore, flexible non-permeable walls closing the bore from the respective air chambers, a member reciprocable in said bore, poppet valves carried by said member and. adapted to cooperate with said valve seats and, in the reciprocation of said member, to connect the chamber toward which it has moved with a source of high pressure and the chamber from which it has moved with a source of low pressure, and a port adapted, when there is slight difference in pressure, to connect one only of said chambers directly with the source of lower pressure.

8. In a milking machine pulsator, the combination of a body, a reciprocable member, valve seats and valves adapted to so cooperate that when said member is at one end of its stroke pneumatic pressures will force it toward the other end of its stroke, and another valve inoperative during normal operation and adapted, when the pulsator is first connected with a source of pneumatic pressure, to be operated to cause an unbalance of pressure that will insure that said member will not remain in a central position.

9. In a milking machine pulsator, operable by differences in pneumatic pressures, the combination of sources of high and low pressure, a stationary body, a member reciprocable therein, means, comprising valves, passages and air chambers, arranged in said body and carried by said member, adapted, when said member is at either end of its stroke, to create unbalanced pressures adapted to force said member toward the other end of its stroke, a passage from one of said air pressure chambers adjacent one end of the member to the source of lower pressure, and a valve adapted to close said passage on the establishment in said last specified chamber of a pressure substantially below the higher pressure.

JOHN L. HULBERT.

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