Patent GB-1396429-A (GB)
Title: Milker control
IPC: A01J5/00
Filed: 1972-10-31
Abstract: 1396429 Milking machines BABSON BROS CO 31 Oct 1972 [31 Jan 1972] 50164/72 Heading A1M An automatic milker unit has means for sensing the flow of milk from each teat cup which, on cessation of flow from a teat cup actuates a time delay circuit which operates to cause a pneumatic piston to remove that cup from the animal. The arrangement is such that a dribble of milk during the delay time will not prevent teat cup removal, but a resumption of steady flow will prevent removal until a subsequent cessation of flow. A circuit is provided for disabling the flow sensing circuits to permit an operator to attach the teat cups at the start of the milking operation. The four sensing circuits of the milker are connected with an output circuit which detects the absence of flow from all four quarters of the cow and produces a "not milking" signal for energising indicators or other purposes. This output circuit also produces a "milking" signal to energise a motor for supplying feed to the animal as long as milk is flowing from any quarter. The flow from a teat cup passes through a detector 15, 22 having an electrically conductive probe 22 contacting the milk when it is flowing. The probe 22 is connected to a liquid sensing circuit 23 which controls an air valve 24 connected to a pneumatic piston (not shown) for removing the teat cup. A capacitor 46 is positively charged while milk is flowing, so that a transistor switch 36 conducts and a transistor switch 37 is off. When milk ceases to flow the path between the probe 22 and ground is broken and capacitor 46 is charged negatively by way of a transformer 52 and diode 53. Switch 36 ceases to conduct. Capacitor 39 then begins to be charged at a rate determined by a circuit 38 providing an adjustable delay of 1-5 seconds. Switch 37 is thereafter turned on and energises indicator lamps 43, 44 and also energises the air valve 24 to actuate the piston removing the teat cup. Capacitor 46 charges negatively more rapidly than positively to ensure that a dribbling or sloshing of milk in well 15 after capacitor 46 is negatively charged will not interrupt removal. An inhibit circuit 32 disables the sensing circuit 23 at the start of the milking operation. On closing a switch 76 a capacitor 63 is charged and causes transistors 60-62 to conduct, thereby grounding the base of a transistor 37a and preventing transistor switch 37 from conducting. Capacitor 63 discharges through a resistor 67 and potentiometer 68 thus turning transistor 61 off at the end of the delay period. A reduced inhibit period permitting replacement of a teat cup that falls off or is removed prematurely is obtained by momentarily closing a switch 81 to charge the capacitor 63 to a lower voltage. Each teat cup is associated with its own detector, sensing circuit 23, air valve 24 and pneumatic piston. An output circuit 33 has a first transistor switch 90 which is connected through a diode 93 with the collector circuit of switch 37, and is connected with the corresponding transistor switches of the sensing circuits for the other three quarters of the cow through diodes 95, so that the transistor switch 90 conducts as long as milk flows from any quarter. The collector circuit of switch 90 includes an indicator light 98 and a motor drive relay 99 for a feed mechanism. When all flow ceases, switch 90 ceases to conduct, causing a switch 91 to conduct and operate a control device (unspecified) or an indicator lamp 104. The flow detectors and teat cup removal mechanism may be as described in Specification 1383038. Specification 1396430 is referred to.