Patent GB-1497055-A (GB)
Title: Milking machines incorporating control arrangements responsive to liquid flow rate
IPC: G05D7/01
Filed: 1974-06-28
Abstract: 1497055 Fluid-pressure servomotor systems SIMPLEX OF CAMBRIDGE Ltd 23 May 1975 [28 June 1974] 28830/74 Heading G3P [ Also in Division A1] A milking machine includes a control device responsive to the rate of flow of milk and arranged to control actuating means for withdrawing the teat cups from an animal's udders when the milk flow-rate falls below a predetermined value corresponding to the completion of the milking operation. As shown in Fig. 1 the control device comprises an outer container 1 inside which is an open topped vessel 5 into which an inlet tube 2 projects downwardly and in the base of which is an aperture 6. The outer container 1 has an outlet tube 3 in its base. As liquid enters the vessel 5 at a rate greater than a predetermined value the vessel fills causing it to fall under gravity bearing down on arm 7 attached to a shaft 8 to raise a weighted lever 9 to its upper position a weight 10 acting as a biasing force. A trigger release member 22 is eccentrically pivoted with respect to the shaft 8 and is lowered as the vessel 5 falls causing a shoulder 15 on the trigger release member to engage a trigger element 20. When the liquid flow-rate falls below the predetermined value the-vessel 5 will empty through aperture 6 until, when the level of liquid in the vessel 5 falls below a certain point, it will rise to its upper position under the action of the weighted lever 9. The trigger release member is thus lifted, the shoulder 15 lifts the trigger element 20 to release a pawl 21 and permit a control lever 11 to pivot about its support. The lever 11 has a weight 13 at one end and an elongate hook 14 at the other end. The elongate hook engages between its limbs a lug 16 projecting from a closure member 17 of a valve 18. Thus, a lowering of the control lever 11 will open valve 18 which is closed when the lever 11 is maintained in its upper, loaded, position. The trigger release member 22 has a cam surface 26 which engages a lug 25 such that, as the member 22 continues to rise, the shoulder 15 is disengaged from the trigger element 20. The control device 30 can be incorporated into a milking machine as shown in Fig. 2 wherein it is inserted into a milk flow line 31 which connects a teat-cup cluster 32 to a vacuum milk collecting jar 27 connected to a vacuum supply (not shown) by a tube 31a. When milking starts the flow of milk is above the predetermined value, the control lever 11 is in its upper, loaded position and the valve 18 is closed. As milking continues, the milk flow-rate decreases and finally falls below the predetermined value when the control device functions, as described above, to open valve 18. This opening of valve 18 connects a piston and cylinder device 33 via a tube 28 to the vacuum supply via a tube 29. The piston 34 rises, pulling on a flexible cable or cord 35 to close a vacuum shut-off valve 36 which is biased into the open position. The teat-cup cluster 32 may then fall under its own weight and be withdrawn by the pull on the flexible cord 35. At the end of a milking operation the control lever is reloaded by raising it to its upper position, thereby closing the valve 18. The control lever 11 may alternatively be reloaded automatically. The valve 18 may be replaced by the valve of Fig. 4 (not shown) wherein the closure member 17  is a circular disc with a hollowed out recess in one of its flat faces arranged to link one of two outer ports (49, 50) formed in the valve body (40) with a central port (51). A milking machine incorporating a control device 30 with the modified valve 18 of (Fig. 4) is illustrated in Fig. 3. At the start of milking the recess in the valve member 17 links the central port with the right-hand port thus connecting the teatcup cluster 32 to the vacuum section (not shown). When the milk flow-rate drops so as to activate the control device as described above the valve member is slid to the left to connect the central port with the left hand port cutting of the vacuum supply to and admitting air into the collecting jar 27 and teatcup cluster 32. At the same time the piston and cylinder arrangement 33 is activated to remove the teat-cup cluster 32, there being no vacuum shut-off valve equivalent to 36 of Fig. 2. Air is also admitted into a vacuum operated ram 61 thus permitting a valve 59 open. The jar 27 is emptied into the vacuum milk pipeline 57, a spherical rubber sealing member 65 being provided to prevent air from being sucked into the pipeline 57. In the embodiment of the control device of (Fig. 5), the vessel 5 is replaced by a float (76) located within a vacuum-tight chamber (70)  having an inlet tube (71) and an outlet tube (72) for connection to the upstream and downstream sections respectively of the flow line of a milking machine, a bleed orifice (73) connected via a tube (74) to the downstream section. Alternatively, the separate outlet tube (72) and bleed orifice (73) may be replaced by a single rigid tube connected outside the chamber (70) to the downstream section of the flow line, projecting to the top of the interior of the chamber through the bottom thereof and having a bleed orifice in the tube towards the bottom of the container.