Fluid handling – Systems – Programmer or timer
Patent
1999-11-29
2000-12-19
Lee, Kevin
Fluid handling
Systems
Programmer or timer
137103, 137105, 119 1441, A01J 504
Patent
active
061615803
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention refers to a pulsator according to the preamble of claim 1.
Today, such pulsators are used in milking machines for alternate pulsation of two pairs of teatcups between a suction phase, i.e. usually a sub-atmospheric pressure, and a pressure phase, i.e. usually atmospheric pressure. During alternate pulsation, the pulsation cycle, i.e. the sum of the suction time and the pressure time, for one of the pairs of teatcups is displaced in relation to the pulsation cycle for the other pair. This means that one of the teatcup pairs is essentially in the suction phase and the other of the pairs essentially in the pressure phase. It is important that the suction phases of both the teatcup pairs have the same duration in order to avoid an uneven milking of the teats. This difference between the duration of the suction phases which is provided by a pulsator is called limping.
2. Description of the Prior Art
SE-B-344 531 discloses a pulsator of the type initially defined and intended for a milking machine. The adjustment of the second circuit is performed by this known pulsator by means of a change-over mechanism, comprising a change-over arm provided on the valve element, a change-over spring and a valve slide. The change-over arm is pivotably attached to a housing of the pulsator and is forcibly pivoted back and forth about a pivot point by means of the movements back and forth of the valve element. The valve slide has two curved surfaces which are intended to slide in turn against a corresponding curved surface of the change-over arm. These surfaces co-operate for controlling the time moments for the change-over of the valve slide from one end position to another. One problem with this known pulsator is that the change-over mechanism comprises many moveable, mechanical construction parts which have to be manufactured with high precision, which makes the production of the pulsator expensive. Due to the many parts and the friction which arises between these parts, there is also a slowness of the change-over mechanism, which results in a mechanical work to be overcome. In addition, the level of the slowness is difficult to determine and is changed with the wear of the parts of the change-over mechanism. Moreover, due to the wear, regular service of the pulsator is required in order to enable the maintenance of a desired pulsation accuracy. Furthermore, the limping of this known pulsator is at least not easily adjustable.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a self-controlled pulsator by which the problems mentioned above may be remedied. In particular, it is aimed at a pulsator of a simple and reliable construction having few moveable parts.
This object is obtained by the pulsator initially defined and characterized in that the second circuit comprises valve members which are arranged to enable change-over of the second circuit from one of said stable positions to the other of these positions by means of a connection of short duration of a control inlet of said valve members to the second pressure source. By such valve members controlled by a short connection, or a pulse-shaped connection, the bistable second circuit may be operated by a minimum of moveable parts. In this manner, it is possible to reduce the slowness which did arise during the change-over between the two stable positions according to the technique previously known.
According to an embodiment of the invention, said control inlet comprises a closing member, which at a rest position closes the control inlet, and the valve element comprises a portion arranged to influence the closing member in such a manner that the control inlet is opened at said change-over. In such a manner, the movement of the valve element of the first circuit may be utilized to provide a short connection or a pulse-shaped connection. The closing member may be designed in a plurality of different manners, for instance as a membrane biased against a seat and openable by
REFERENCES:
patent: 4643132 (1987-02-01), Icking et al.
patent: 5010844 (1991-04-01), Tackeuchi et al.
patent: 5167200 (1992-12-01), Icking
patent: 5207177 (1993-05-01), Lidman
Alfa Laval Agri AB
Lee Kevin
LandOfFree
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