WO1989002216A1

WO1989002216A1 - Pulsator, preferably for milking machines

Info

Publication number: WO1989002216A1
Application number: PCT/SE1988/000451
Authority: WO
Inventors: Rutger Nilsson
Original assignee: Alfa-Laval Agriculture International Ab
Priority date: 1987-09-14
Filing date: 1988-09-02
Publication date: 1989-03-23
Also published as: SE8703538D0; SE8703538L; DK64890A; EP0380514A1; SE467183B; DK64890D0

Abstract

A pulsator, preferably for milking machines, comprises a housing (1) with a vacuum channel (13) and two pulsation channels (15, 16) for connection to respective pairs of teat cups. A slide valve (17) is arranged displaceably in the housing across the openings of the channels between two end positions and has a recess (21) for connection of the vacuum channel with only one of the pulsation channels when the slide valve is in one of its end positions and with only the other of the pulsation channels when the slide valve is in its other end position. The invention is characterized by means (23, 24, 28, 29, 33) for adjustment of the end positions of the slide valve (17) relative to said openings of the vacuum and pulsation channels (13, 15, 16) in the direction of movement of the slide valve, in such a way that the stroke of the slide valve between said end positions remains unchanged. By means of said adjustment means the limping of the pulsator can be adjusted, so that it will be acceptably small or completely eliminated.

Description

Pulsator, preferably for milking machines

The present invention relates to a pulsator, preferably for milking machines, comprising a housing forming a chamber, a vacuum channel for connection to a vacuum source, which vacuum channel extends from the outside of the housing through a wall portion of the housing and opens into the chamber, two pulsation channels for connection to the respective pulsation spaces in two pairs of teat cups of a milking means, which pulsation channels extend from the outside of the housing through said wall portion of the housing and opens into the chamber on both sides of the opening of cLe vacuum channel in the latter, and a slide valve, which is arranged displaceably across the openings of the channels in the chamber between two end positions there- in. The slide valve is provided with a recess for connection of the vacuum channel with only one of the pulsation channels when the slide valve is in one of its end positions and with only the other of the pulsation channels when the slide valve is in its other end position.

A pulsator of this kind is disclosed for instance in US-PS 3 448 756 and is used in milking machines for alternate pulsation of two pairs of teat cups. When alternately pulsating, the pulsation cycle, i.e. the sum of the suction time and the pressure time, for one pair of teat cups is displaced relative to the pulsation cycle for the other pair, so that during the suction phase for one pair of teat cups substantially pressure phase prevails for the other pair of teat cups.

It is important when alternately pulsating that the pulsator generates suction phases, which for the two pairs of teat cups of the same milking means have substantially the same duration, so that uneven dry-milking of the udder of a cow is avoided. The difference between the duration of the suction phases at the respective pairs of teat cups usually caused by a pulsator is called the limping of the pulsator. In many countries the authorities also have issued rules for the highest allowable limping in connection with alternate milking.

The known pulsator is manufactured under very high demands on the tolerances of the included components, whereby the limping of the pulsator will be acceptably small or even non-existing. However, the high tolerance demands means the drawback that the price for manufacturing the pulsator is substantially raised because of the required finish of the components of the pulsator and precise assemblage of the pulsator.

The object of the present invention is to provide a new inexpen¬ sive pulsator of the present kind, which has an acceptably small or non-existing limping without need for manufacturing the components of the pulsator under high tolerance demands.

This object is obtained by a pulsator of the kind initially stated, which according to the invention is characterized by means for adjustment of the end positions of the slide valve relative to said openings of the vacuum and pulsation channels in the direction of movement of the slide valve, in such a way that the stroke of the slide valve between said end positions remains unchanged.

Said adjustment means enables an easy adjustment of the limping of a pulsator just manufactured, so that this limping will be acceptably small or even eliminated. The tolerance demands on the components of the pulsator, which affects the limping, therefore can be substantially reduced. In addition, recurrent adjustments of the limping of pulsators in operation will be made possible, since pulsators normally limp in an ever increasing extent as they are worn. In the known kind of pulsator, in which a spindle is arranged axially reciprocating for entraining the slide valve between said end positions, said adjustment means according to the invention comprises a member coupled between the spindle and the slide valve, which coupling member is arranged adjustably relative to the slide valve along its direction of movement.

Said reciprocating spindle is preferably provided in a known way with two entrainment members, one of the entrainment member being adapted to entrain the slide valve in one of its direc¬ tions of movement, while the other entrainment member is adapted to entrain the slide valve in the opposite direction of movement. The coupling member according to the invention is arranged between the entrainment members, such that when entraining the slide valve the corresponding active entrainment member abuts against the coupling member.

According to one embodiment of the pulsator according to the invention the coupling member is in friction engagement with the slide valve and is arranged displaceably relative to the latter along its direction of movement. Hereby, a separate adjustment means can be utilized for adjustment of the limping during operation of the pulsator. The separate adjustment means is for this purpose suitably placeable in the chamber between the wall of the housing and the slide valve on one side of the slide valve seen in its direction of movement. With the adjust¬ ment means placed in this way the slide valve will abut against the adjustment means during the operation of the pulsator and thereby be displaced relative to the coupling means.

Suitably, the coupling means is provided with a dovetail guide, which is fitted in a correspondingly shaped recess in the slide valve. Alternatively, the coupling means may be a rod extending through an elongated hole in the slide valve. According to another embodiment of the pulsator according to the invention the coupling means comprises a screw, which extends through a hole in the slide valve and which is in threaded engagement with the latter. The screw is suitably provided with a screw head for engagement with a wrench.

Alternatively, said adjustment means may comprise a plate member arranged between the slide valve and the openings of the channels in the chamber, the plate member being provided with three through holes, situated substantially in front of the openings of the channels and being arranged adjustably relative to the slide valve in its direction of movement.

The invention will be described more closely with reference to the accompanying drawing, in which figure 1 shows a section through a pulsator according to one embodiment of the invention, figure 2 shows a front view of an embodiment of the coupling - member according to the invention, figure 3 shows a section along the line III-III in figure 2, figure 4 shows a separate adjustment means, figure 5 shows a side view of another embodi¬ ment of the coupling member according to the invention, figure 6 shows a section along the line VI-VI in figure 5, and figure 7 shows a further separate adjustment means.

The pulsator shown in figure 1 comprises a housing 1 forming a centrally situated chamber 2, which communicates with the atmos¬ phere. A spindle 3 is axially displaceably journalled in two opposite side walls 4, 5 in the chamber 2 and extends into two spaces in the housing situated on each sides of the central chamber 2. The ends of the spindle 3 are connected to two membranes 6, 7 of a flexible material, which divides liquid tightly each of the two spaces into an inner chamber 8, 9 and an outer chamber 10, 11. Via a channel 12 through the spindle 3 the two outer chambers 10, 11 communicate with each other. The closed space formed by the two outer chambers 10, 11 and the channel 12 of the spindle 3 are completely filled with liquid. A vacuum channel 13 for connection to a vacuum source extends from the outside of the housing through a lower wall portion 14 of the housing and opens into the central chamber 2. Two pulsation channels 15, 16 for connection to pulsation spaces in the respective pairs of teat cups of a milking means extend from the outside of the housing through the lower wall portion 14 and opens into the central chamber 2 on both sides of the opening of the vacuum channel 13.

A regulating means not shown in the drawing is adapted to alter¬ nately connect the inner chambers 8, 9 to the vacuum channel 13 and atmosphere, respectively, in response to the position of the spindle 3 relative to the housing. (Said regulating means is completely described in US-PS 3 448 756). If vacuum prevails in the right inner chamber 9 and atmospheric pressure in the left inner chamber 8 during operation of the pulsator, the spindle 3 moves to the left because of the pressure difference across the right membrane 7. At this, liquid is pressed from the left outer chamber 10 via the channel 12 of the spindle 3 into the right outer chamber 11, the velocity of the spindle being determined by the size of the liquid flow in the channel 12. When the spindle 3 has been moved to a first predetermined position relative to the housing 1, the regulating means alternate the connections of the inner chambers 8, 9, so that vacuum prevails in the left chamber 8 and atmospheric pressure prevails in the right chamber 9. Now the spindle 3 moves to the right to a second predetermined position, in which the regulating means again alternates the connections of the inner chambers 8, 9, and so forth.

A slide valve 17 is arranged slidably across the openings of the vacuum and pulsation channels. The slide valve 17 is provided with an elongated upper part 18, extending along the spindle 3 and abutting against the latter. Two entrainment members 19, 20 in the form of two washers are attached to the shaft 3 on each side of the upper part 18 of the slide valve. The entrainment members 19, 20 are adapted to entrain the slide valve 17 during the movement of the spindle 3, so that the slide valve 17 is displaced back, and forth between two end positions in the housing 1. A recess 21 in the underside of the slide valve connects the vacuum channel 13 to the left pulsation channel 15 when the slide valve 17 is in its left end position, and to the right pulsation channel 16 when the slide valve is in the right end position shown in figure 1.

A coupling member in the form of a rod 22 extends through a hole

23 in the upper part 18 of the slide valve and abuts with its ends against the entrainment members 19, 20. Thus, these entrain the slide valve 17 through the rod 18. The rod 18 is in friction engagement with the slide valve 17, which friction engagement is dimensioned such that during the normal operation of the pulsa¬ tor a relative displacement between the rod 18 and the slide valve 17 is prevented, while such a displacement is allowed if the slide valve 17 abuts against a separate adjustment means, for instance a thickness gauge, which is placed between the wall of the housing and the slide valve. By means of a pulsometer coupled to the pulsator the limping of the latter may be adjusted during operation by means of said separate adjustment means.

The coupling member shown in figures 2 and 3 is constituted by an upper separate part 24 of the slide valve. The separate part

24 is by means of a dovetail guide 25, which is fitted in a correspondingly shaped recess 26 in the lower part 27 of the slide valve, arranged displaceably relative to the latter. A separate elongated adjustment means 28 (figure 4) with an oval cross section is placeable between the lower part 27 of the slide valve and the wall of the housing. By turning the adjust¬ ment means 28 the limping may be adjusted during operation of the pulsator in a corresponding way as described above for the embodiment according to figure 1. The adjustment means 28 according to figure 4 may of course also be utilized for adjustment of the limping of a pulsator provided with the coupling member according to figure 1.

The coupling member shown in figures 5 and 6 is constituted by a screw 29, which extends through a hole 30 in an upper part 31 of the slide valve and which is in threaded engagement with the latter. The ends of the screw 29 protrudes from the hole and are intended to abut against the entrainment member of the pulsator. One of the ends of the screw is provided with a hexagonal screw head 32. By means of a wrench 33 (figure 7) fitting to the screw head 32 the limping of the pulsator can be adjusted by turning the screw 29. However, the adjustment can only be carried through when the movement of the spindle is prevented, for instance by blocking up the regulating means of the pulsator for alternating the direction of movement of the spindle, whereby adjustments may be necessary to accomplish repeatedly before an acceptably small limping is obtained.

Claims

1. A pulsator, preferably for milking machines, comprising a housing (1), forming a chamber (2), a vacuum channel (13) for connection to a vacuum source extending from the outside of the housing through a wall portion (14) of the housing and opening into the chamber, two pulsation channels (15, 16) for connection to pulsation spaces in the respective pairs of teat cups of a milking means, which pulsation channels extend from the outside of the housing through said wall portion of the housing and open into the chamber on each side of the opening of the vacuum channel in the latter, and a slide valve (17) arranged displace¬ ably in the chamber across the openings of the channels between two end positions in the chamber, which slide valve is provided with a recess (21) for connection of the vacuum channel to only one of the pulsation channels when the slide valve is in one of its end positions and with only the other of the pulsation channels when the slide valve is in its other end position, c h a r a c t e r i z e d b y means (23, 24, 28, 29, 33) for adjustment of the end positions of the slide valve (17) relative to said openings of the vacuum and pulsation channels (13, 15, 16) in the direction of movement of the slide valve, in such a way that the stroke of the slide valve between said end positions remains unchanged.

2. A pulsator according to claim 1, in which a spindle (3) is arranged axially reciprocating for entrainment of the slide valve (17) between said end positions, c h a r a c t e ¬ r i z e d i n that said adjustment means comprises a member (23, 24, 29) coupled between the spindle (3) and the slide valve (17), which coupling member is arranged adjustably relative to the slide valve in its direction of movement.

3. A pulsator according to claim 2, in which said reciprocating spindle (3) is provided with two entrainment members (19, 20), one of the entrainment members being adapted to entrain the slide valve (17) in one of its directions of movement while the other entrainment member is adapted to entrain the slide valve in the opposite direction of movement, c h a r a c t e r ¬ i z e d i n that the coupling member (23, 24, 29) is arranged between the entrainment members (19, 20), such that when entraining the slide valve (17) the corresponding active entrainment member abuts against the coupling member.

4. A pulsator according to claim 2 or 3, c h a r a c t e r ¬ i z e d i n that the coupling member (23, 24) is in friction engagement with the slide valve (17) and is arranged displace- ably relative to the latter in its direction of movement.

5. A pulsator according to claim 4, c h a r a c t e r i z e d i n that said adjustment means also comprises a separate adjustment member (28), which is placeable in the chamber (2) between the wall of the housing and the slide valve (17) on each side of the slide valve seen in its direction of movement.

6. A pulsator according to claim 5, c h a r a c t e r i z e d i n that said friction engagement between the coupling member (23, 24) and the slide valve (17) is dimensioned, such that during the normal operation of the pulsator relative displace¬ ment between the coupling member and the slide valve is preven¬ ted, while such a displacement is allowed if the slide valve abuts against said separate adjustment member (28) placed between the wall of the housing and the slide valve.

7. A pulsator according to any of claims 4-6, c h a r a c ¬ t e r i z e d i n that the coupling member (24) is formed with a dovetail guide (25), which is fitted in a correspondingly formed recess (26) in the slide valve.

8. A pulsator according to any of claims 4-6, c h a r a c ¬ t e r i z e d i n that the coupling member (23) is a rod and extends through an elongated hole in the slide valve.

9. A pulsator according to claim 2 or 3, c h a r a c t e r ¬ i z e d i n that the coupling member comprises a screw (29), which extends through a hole (30) in the slide valve and which is in a threaded engagement with the slide valve.

10. A pulsator according to claim 9, c h a r a c t e r ¬ i z e d i n that said adjustment means also comprises a wrench (33) for engagement with a screw head (32) on the screw.