A PILOT DIAPHRAGM VALVE

Abstract: A pilot diaphragm valve (10) for a pulsator in a milking plant comprising a piston diaphragm valve (11), wherein the position of a piston (12) is determined by the pressure on a diaphragm (14) and wherein a diaphragm chamber (22a) on one side of the diaphragm communicates with the pilot valve (13). A toggle arm (26) is arranged in a wall of the pilot valve chamber, and one end of said toggle arm forms a movable valve member (26a) adapted to alternately open and close a vacuum inlet and an air inlet (42, 46). The other end (26b) of the toggle arm protrudes out of the valve chamber (25) and engages a displaceable slider (28) comprising a plurality of permanent magnets (31) mounted in such a manner that two magnetic poles of the same type face each other and may slide into a coil (32) adapted to be connected to an electronic circuit being able to supply the coil with current pulses, the direction of which may alternate at the desired frequency for changing the pressure on the teat cup of the milking machine between vacuum and atmospheric pressure. As a result, a current controlled valve having very small electric power consumption is obtained.

Description: Title: A pilot diaphragm valve ~ f Technical Field The present invention relates to a pilot diaphragm val¬ ve, particularly for a pulsator, comprising a piston 5 diaphragm valve of the type stated in the preamble to claim 1 for a milking plant Background Art Such valves are known from GB-A-2 095 528. The position of the valve members are controlled by electromagnets. 10 At the use of such valve it is essential to minimize the power consumption of the electromagnets. Disclosure of the Invention According to the invention a pilot diaphragm valve is provided, in particular for a pulsator comprising a pis- 15 ton diaphragm valve, wherein the position of a piston is determined by the pressure on a diaphragm and wherein a diaphragm chamber on one side of the diaphragm is con¬ nected to the chamber of a pilot valve by means of an air conduct, said pilot chamber having a first and a 20 second inlet -vith a first and second pressure, respec¬ tively, and wherein a movable valve member is arranged for alternate., * ; closing the first and second inlet, said valve furthei comprising a cylinder provided with a coil form having a coil adapted to be connected to an elec- 25 tronic circuit being able to supply said coil with cur¬ rent pulses, the direction of which may alternate at a predetermined frequency and wherein all of the valve members are made of an essentially non-magnetic material such as plastics. The valve is characterised in that a toggle arm is til- tably arranged in or adjacent a wall of the pilot valve chamber, one end of said toggle arm forming the movable valve member and the other end protruding out through the wall and engaging a displaceable slider comprising a plurality of permanent magnets mounted in a series, wherein two magnetics poles of the same type face each other, said slider arranged so as to slide in the cylin¬ der. As the magnetic core comprises permanent magnets being mounted with opposite polarity, the tractive ef¬ fort curve of the magnetic core is a relatively flat curve in the entire area of motion. By using a toggle arm it is possible to incorporate a gearing in the sy¬ stem. A considerable advantage of the new construction is that the sliders carrying the permanent magnets may be displaced by supplying the colis with relatively weak current pulses, whereby the power consumption (the cur¬ rent pulses through the coil) is considerably smaller than at known systems. In a perferred embodiment of the invention three magnets are arranged in the cylinder, the two upper magnets having poles of the same type facing each other through an intermediate layer of a non-magnetic material, and the two lower magnets having their poles in the same direction thus forming a rod magnet having a single north pole at one end and a single south pole at the other end. Two iron rings are preferably mounted about the cylin¬ der, one on each side of the coil. The iron rings lock the magnetic core in its outermost positions. When an electric current pulse has guided the slider with the magnets into an outermost position, the slider is re¬ tained in this outermost position without additional electric power due to the force of attraction between the magnet and the adjacent iron ring in said outermost ( * -* position. As a result, a current operated valve having a very small power consumption is obtained. In a preferred embodiment of the invention the valve has 5 a power consumption of approximately 0.01 watt, which is approximately 200 times less than other hitherto known low energy valves. Brief Description of the Drawings The invention is described in greater detail in the fol- 10 lowing with examples and with reference to the accom¬ panying drawings , in which Fig. 1 is an elevational, cross-sectional view of an example of an embodiment of a pilot diaphragm valve ac¬ cording to the invention, in a first position, 15 Fig. 2 the same as Fig. 1 in a second positon. Best Mode for carrying out the invention Fig. 1 illustrates a preferred embodiment of a pilot diaphragm valve (10) , essentially being made of plastics and forming part of an electronic pulsator for a milking 20 plant. The diaphragm valve is viewed in section on the lower portion of Fig. 1. A piston (12) is attached to a diaphragm (14) , which may be made of rubber. In the bot¬ tom position, referred to as position 1 in Fig. 1, a piston member (16) sealingly abuts a gasket (18) at the 25 bottom of a valve chamber. A channel (54) under a con¬ tinuous vacuum is provided underneath the piston member (16). A circumferential chamber (50) is provided above the piston member (16) , said chamber being connected to a channel (52) leading to the teat cup of the milking plant . In the bottom position the chamber (50) communicates with a second circumferential chamber (20) with connec¬ tion to a chamber or channel having a constant pressure of approximate 1 atmosphere. The diaphragm (14) is able move upwards and downwards between position 1 and posi¬ tion 2 in a diaphragm chamber (22) . An air conduct is provided at (24) , said conduct leading to a valve cham¬ ber (25) in a pilot valve (13). A toggle arm (26) is provided in a wall (if desired, a supporting wall adap¬ ted thereto) of the pilot valve, one end of the toggle arm being formed as a valve member (26a) and the other end (26b) being connected to a slider (28). The slider (28) comprises a plurality of permanent mag¬ nets, three magnets illustrated in the example, posi¬ tioned in such manner that the poles mentioned in an order from top to bottom are N-S , S-N , S-N . The magnets thus form two rod magnets having opposite S-poles and only separated by an intermediate layer of plastics or another non-magnetic material. The entire slider is pre¬ ferably covered by a plastics casing thus holding the magnets together. The slider (28) functions as a piston sliding inside a plastics cylinder, which at the same time forms a coil form retaining a coil (32), the windings of said coil being arranged approximately centrally about the cylin¬ der (30) . An iron ring (34) is provided about the cylin- der above the coil and another iron ring (36) is mounted about the cylinder (30) below the coil. One end of the toggle arm (26) communicates with the slider (28) in such manner that the toggle arm follows the upwards and downwards movement of the slider in the cylinder (30) . In the shown embodiment the slider (28) is provided with an extension or projection (29) with a hole through which one end of the toggle arm (26) may protrude . The coil (32) communicates with an electronic control circuit supllying an operative current through the coil. Depending on the direction of the current, the magnetic slider (28) is displaced upwards or downwards. In position 1 shown in Fig. 1 the slider is retained by gravity and to some extent by forces between the magnets (31b, 31c) and the lowermost iron ring (36) . As can be seen from Fig. 1 the left portion (26b) of the toggle arm is pressed downwards into position 1 and the right, short portion (26a) (extending into the pilot diaphragm valve chamber (25) , into which the air conduct (24) opens) is pressed upwards and covers the opening (42) leading into a channel (44) under continuous vacuum. When a short current pulse is passed through the coil (32) , a force arises between the coil (32) and the mag¬ netic core (31) overcoming the mentioned retaining force? (gravity and any forces between the magnets (31bc and the adjacent iron ring (36)) and setting the slider into motion towards the second position, position 2 of Fig. 2. The slider is then retained in this posi¬ tion by means of a force between the uppermost iron ring (34) and the uppermost magnet (31a) and by a force bet¬ ween the lowermost iron ring (36) and the lowermost pole in the magnet (31c) . As a result, a retaining force is obtained in position 2 of Fig. 2, said force being sufficiently strong to force the valve member (26a) to close and air inlet (46) to an air conduct (48) having approximately 1 atmosphere, when the valve chamber (25), the air conduct (24) and the diaphragm chamber (22) are under vacuum. At the next opposite current pulse, the slider is de¬ tached from position 2 and set into downward motion to¬ wards position 1, at which position it is retained by gravity and the forces between the lowermost iron ring (36) and the lowermost magnets (31bc) , until the subse- quent current pulse. When the magnets are pressed up into the upper position, the left portion (26b) of the toggle arm is lifted into position 2 and the right portion (26a) tilts downwards and closes an opening (46) leading to a channel (48) having a constant atmospheric air pressure. At the same time the opening (42) to the channel (44) under constant vacuum is opened. Vacuum is passed through the air conduct (24) to the diaphragm chamber (22) and the diaphragm is pressed into position 2. The piston (12) follows said diaphragm and the piston member (16) is lifted to sealingly abut a gasket (58) and the chamber (20). In this upper position the vacuum channel (54) communicates with the chamber (50) and the channel (52) leading to the teat cup. The structure of the pilot valve is characterised in that the magnetic core (31) comprises permanent magnets provided with opposite polarity effecting that the trac¬ tive force curve of the magnetic core is relatively flat in the entire area of motion. The two stationary iron rings (34,36) lock the magnetic core in the outermost position, whereby the valve may be operated by means of short current pulses with a conse¬ quently low energy consumption. Due to the two opposite magnets in the coil core (31) , the magnetic core (31) functions under essentially the same tractive force over a relatively long section, that is to say approximately 3 mm. Moreover, as a result thereof, the core may be locked in one or both outermost positions, whereby the core may used to operate the toggle arm system (26a, 26b) with a built-in gearing, for instance in the area of approxima¬ tely 1:2 to approximately 1:4. The toggle arm system is provided with the valve member (26a) which opens and closes the two air conducts (44,48) , respectively. The constant force, which is to close the air conduct, is provided by means of the magnet/iron ring (34,36) with¬ out supply of additional energy. The shown construction is advantageous in that only a very small and short operative current is required to magnetise the coil into a displacement of the slider and thus of the toggle arm, whereby the valve position chan¬ ges from position 1 to position 2 or visa versa. In the above described embodiment the valve acts as a bistable pulse valve. By altering the position of the iron ring, the valve may be changed to a monostable constant current valve to form part of other operative systems. The energy con¬ sumption, however, then increases to approximately 0.1 watt at this type of valve. The present invention may be employed in other ways than illustrated on the accompanying drawings, which are re— present merely examples of use. The number and type of the used permanent magnets may thus vary, just as the specific form of the valve members and the valve cham¬ bers may be altered, if needed. The valve of the above embodiment is provided with a vertical, displaceable slider closing the vacuum channel in position 1. In a alternative embodiment the valve may be rotated 180° or the vacuum inlet and the air inlet may be interchanged so that gravity (due to the weight of the magnets) con- tributes to pressing the pilot valve member against the air conduct. In this embodiment it may be advantageous to arrange an additional iron ring subjacent to the ring (36) for retaining the slider in position 1. The actual size and placing of the iron rings (34,26) should be chosen with regard to obtaining and maintaining the de¬ sired outermost positions.

Claims: C l a ims 1. A pilot diaphragm valve (10) , particularly for a pulsator, comprising a piston diaphragm valve (11), whe¬ rein the position of a piston (12) is determined by the pressure on a diaphragm (14) and wherein a diaphragm chamber (22a) on one side of the diaphragm communicates with the pilot valve chamber (25) of a pilot valve (13) by means of an air conduct (24) , said pilot chamber (25) having a first and a second inlet (42,46) with a first and second pressure, respectively, and wherein a movable valve member (26a) is arranged for alternately closing the first and second inlet (42,46) , and said valve fur¬ ther comprising a cylinder (30) provided with a coil form having a coil adapted to be connected to an elec- tronic circuit being able to supply said coil with cur¬ rent pulses, the direction of which may alternate at a predetermined frequency and wherein all of the valve members are made of an essentially non-magnetic material such as plastics, c h a r a c t e r i s e d in that a toggle arm (26) is tiltably arranged in or adjacent a wall of the pilot valve chamber (25), one end of said toggle arm forming the movable valve member (26a) and the other end (26b) protruding out through the wall and engaging a displaceable slider (28) comprising a plura- lity of permanent magnets (31) mounted in a series, whe¬ rein two magnetics poles of the same type face each other, said slider (28) arranged so as to slide in the cylinder (30) . 2. A pilot diaphragm valve as claimed in claim 1, c h a r a c t e r i s e d in that three magnets (31a, 31b, 31c) are arranged in the cylinder, the two upper magnets (31a, 31b) having poles of the same type facing each other through an intermediate layer (33) of a non¬ magnetic material, and the two lower magnets (31b, 31c) having their poles in the same direction thus forming a rod magnet having a single north pole at one end and a single south pole at the other end. 3. A pilot diaphragm valve as claimed in claim 2, c h a r a c t e r i s e d in that at least one statio¬ nary iron ring is provided on outer face of the cylinder (30) for locking the magnetic core in at least one ou¬ termost position. 4. A pilot diaphragm valve as claimed in claims 1, 2 or 3, c h a r a c t e r i s e d in that at least two stationary iron rings (34,36) are provided on the outer face of the cylinder (30) for locking the magnetic core in two outermost positions. 5. A pilot diaphragm valve as claimed in one or more of the claims 1 to 4, c h a r a c t e r i s e d in that the toggle arm (26) is adapted to provide a built-in gearing, preferably a gearing on approximately from 1:2 to approximately 1:4. 6. A pilot diaphragm valve according to one or more of the claims 1 to 5, c h a r a c t e r i s e d in that two stationary iron rings are arranged so as to attract one end of each of the magnets of the slider in one of the outermost positions.

Inventors: LINDHOLST TORBEN K, LINDHOLST, TORBEN, K.
Applicants: CHRISTENSEN & CO AS S A, AKTIESELSKABET S.A. CHRISTENSEN & CO.
Application year: 1993
Main classification: F16K31
IPC codes: A01J5, F16K31