GB2394291A

GB2394291A - Sensing system for a milking installation

Info

Publication number: GB2394291A
Application number: GB0224019A
Authority: GB
Inventors: Paul Crudge; John Gillen
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-10-16
Filing date: 2002-10-16
Publication date: 2004-04-21
Anticipated expiration: 2022-10-16
Also published as: WO2004034774A2; GB0224019D0; GB2394291B; AU2003274324A1; WO2004034774A3; AU2003274324A8

Abstract

A sensor for detecting loss of vacuum in a milking system is disclosed. The sensor has a diaphragm, a first side of which is for connection to a milk flow line at a pressure below atmospheric pressure. The second side of the diaphragm is for connection to a vacuum line. Variation in the pressure across the diaphragm causes movement in the diaphragm, and such movement causes a variation in output of the sensor, for example, by varying a pressure in an output line of the sensor.

Description

1 23942g1 Sensing system for a milking installation This invention relates

to a sensing system for use in a milking installation and a sensor 5 for use in such a system. In particular, it relates to a sensing system that can be used to detect liner slip or kick-off during milking, or other causes of vacuum loss in apparatus associated with a milking station.

Apparatus for automated milking of dairy cows relies on maintaining a vacuum seal between each of the cow's teats and the liner within the teat cup. This seal can 10 partially break down in a condition known as "liner slip", or the vacuum can be lost entirely if one or more of the teat cups becomes detached, for example, if it is kicked off by the cow.

When liner slip occurs, the increased flow of air from the cluster changes the characteristics of air and milk flow within the milking system. This occurrence can 15 cause other sensing components of the system, particularly milk flow sensors, to give an inaccurate reading if it is not detected and accommodated. The air admission from liner slips can also contribute to an increased risk of mastitis, by accelerating potentially contaminated droplets of milk into the teat sinus. Kick-off can cause the teat cup to land on the floor of the milking parlour, from which it can quickly draw in 20 contaminants, which may result in the loss of a significant quantity of milk. There is therefore a clear demand for a reliable sensing system that can detect both liner slip and kick- off. Since these conditions can occur independently at any one of several milking stations, an independent sensing system is required for each milking station.

Therefore, it is highly desirable that any such system adds a minimum of complexity 25 and cost to an existing milking installation.

In WO-A-9617509 there is disclosed a system for monitoring pressure that could be employed to detect liner slip or kick-off. However, providing such a system involves

modification to the teat cups, and it therefore cannot readily be retrofitted to existing milking systems without significant work and expense.

WO-A-OI 17335 discloses a method for detecting liner slip and kick-off in a milking installation, but does not provide suitable apparatus for performing the method 5 disclosed.

In many milking installations, each milking station is provided with a pilot-operated diaphragm valve, which can selectively connect the station to or disconnect the station from the vacuum source that carries milk from the milking installation. Such a valve can be controlled by a solenoid, thereby allowing the milking station to be connected 10 or disconnected under electronic control. The present inventors have realised that a sensor to detect liner slip or kick-off can readily be incorporated into such a valve.

Therefore, from a first aspect, this invention provides a sensor for detecting loss of vacuum in a milking system, the sensor comprising a diaphragm a first side of which is for connection to a milk flow line at a pressure below atmospheric pressure and the 15 second side of which is for connection to a vacuum line, in which variation in the pressure across the diaphragm causes movement in the diaphragm, such movement causing a variation in output of the sensor.

When the sensor is connected across lines that are at equal pressure in normal use, the sensor is not affected by changes in the absolute pressure of the partial vacuum.

20 The output of the sensor may be a variable air pressure in an output line. The air pressure may be variable between a vacuum line pressure and atmospheric. Such a sensor may further comprise a pressure transducer connected to the output line for converting the pressure in the line to an electrical output signal.

For example, the diaphragm may act as a valve to open or close a flow passage 25 between the output line and the vacuum line. In the event that such a flow passage is open, the pressure sensed by the transducer may be approximately that in the vacuum line. In the event that the flow passage is closed, the pressure output may rise towards atmospheric.

( 3 In particularly convenient embodiments, the diaphragm may be the diaphragm of a flow control valve, such as a pilot-operated diaphragm valve. This can provide a sensor with by way of minimal addition to a conventional system. In such embodiments, the flow control valve provides two distinct functions: controlling flow and acting as a 5 sensor. It may be possible to convert existing flow control valves to operate as sensors embodying the invention. In such cases, an output line may be connected to a control chamber of the valve. For instance, such a valve may be suitable for connection in a milk flow line to control flow of milk and air through the pipe.

From another aspect, this invention provides a system for detecting leakage of vacuum 10 in a milking system comprising a sensor according to the first aspect of the invention and a processor for processing the output of the sensor.

In such a system, signals from the sensor can be analysed to determine the cause of the loss of vacuum. Typically, the cause may be identified as one of liner slip or kick-off.

The invention also provides a milking installation comprising a sensor embodying the 15 first aspect of the invention connected between a milk flow line and a vacuum line.

The installation may further comprise a milk flow meter in the milk flow line, processing of signals from the meter being modified in response to signals output by the sensor.

It will be understood that references to a "vacuum" in this specification in fact relate

20 to a partial vacuum. Typical pressures in the vacuum line may be in the region of approximately 50 kPa vacuum.

An embodiment of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings, in which: Figure I is an exploded diagram of a sensor being a first embodiment of the invention; 25 Figure 2 the internal structure of a cover component of the embodiment of Figure 1; Figure 3 shows enlarged details of a component of the embodiment of Figure 1;

( 4 Figure 4 diagrammatically illustrates the sensor of Figure I connected into a milking installation; Figure 5 illustrates output of the sensor of Figure I during onset of liner slip; and Figure 6 illustrates output of the sensor of Figure I upon the occurrence of kick-ok 5 A sensor embodying the invention is embodied in combination with a pilot- controlled flow valve. The valve comprises a valve body 10, a diaphragm 12, a cover 14 and a locking ring 16. The valve is incorporated into a milk flow tube of a milking installation to control the flow of milk from a milking station. I The valve body 10, a one-piece moulding of plastic, has an annular valve chamber 20.

10 An inlet port 22 extends radially from the valve chamber 20 providing a passage through which air and milk can enter the valve chamber 20. An outlet port 24 extends axially from within the chamber 20 to provide an outlet passage through which air and milk can leave the chamber 20. The outlet port 24 projects axially within the chamber from a closed base wall 26 of the chamber towards an open upper end of the chamber 15 20. At the open end, a radial sealing surface 28 surrounded by a retaining wall 30 is formed on the body. The valve body is connected to a flow line through which a mixture of milk and air flows under the action of a partial vacuum.

The diaphragm 12 is formed of flexible rubber or artificial polymer. The diaphragm 12 forms a fluid-tight seal against the sealing surface 28 and has a circular periphery that is 20 a close fit within the retaining wall 30. A central region of the diaphragm is surrounded by a convoluted section that allows the central region to be deflected axially. An integral annular projection extends from the diaphragm 12 in a direction out of the valve chamber 20.

The cover 14 has a dome formation, which encloses an air control chamber 40. A 25 peripheral sealing rim 42 of the cover 14 abuts a peripheral region of the diaphragm 12. The locking ring 16 is applied to clamp the cover 14 to the body 10 thereby trapping the diaphragm securely between the cover 14 and the body 10. Centrally of the cover 14, an annular projection 48 extends to surround the projection of the

( 5 diaphragm 14. A pilot tap 44 passes centrally through the cap 14 to provide a fluid passage into the control chamber 40.

During operation, the valve chamber 20 is at a pressure below atmospheric. Thus, if the pilot tap 44 and the control chamber 40 are at or around atmospheric pressure, 5 the central region of the diaphragm 12 will be urged out, away from the air control chamber 40 into contact with the projecting part of the outlet port 24 within the valve chamber 20. This has the effect of sealing the outlet port 24, thereby preventing passage of fluid out from the valve chamber 20. If the pressure at the pilot tap 44 and control chamber 40 is then reduced towards the pressure in the valve chamber 20, the 10 sealing pressure is removed from the diaphragm 12, which will then withdraw from the outlet port 24, so allowing fluid to flow from the inlet port 22, through the valve chamber 20, to the outlet port 24. In this condition, the pressure in the control chamber 40 is substantially constant and at the same pressure as in the flow line.

Therefore, there is a pressure equilibrium across the diaphragm 12, which allows it to 15 adopt a neutral position within the valve chamber 20. In a typical milking installation, the pilot tap 44 is connected to a vacuum line 60 through a solenoid-operated valve 62. By application of a signal to the solenoid it is, therefore, possible to control the pressure at the pilot tap 44 and thereby open or close the valve.

A vent hole 50 is formed through the dome of the cover 14 connecting the control 20 chamber 40, radially out from the projection 48, to the atmosphere. The hole is of a small size, I mm diameter in this embodiment, so airflow through it is restricted.

Specifically, the rate at which air can flow through the hole is considerably less than the rate at which it can be removed from the control chamber 40 through the pilot tap 44, so that its presence does not affect operation of the valve. A sensing tap 52 also 25 extends through the dome of the cover 14 to within the dome, radially out from the projection 48. The sensing tap 52 is connected by a pipe to a remote pressure transducer 64. During normal operation, the pressure within the control chamber 40 will be uniform, so the pressure measured by the sensor will be that of the vacuum line.

( 6 For use, the valve is connected with its inlet port 22 connected to the claw piece of a milking station (not shown) at A in Figure 4. The outlet port 26 is connected through a milk flow pipe 68 to a milk receptacle 70. The receptacle 70 is connected through a vacuum line 74 to a vacuum pump 76. The solenoid valve 78 is connected in a control 5 line 72 that connects the vacuum line 74 to the pilot tap 44 of the valve. A control unit 80 receives signals from the transducer 64 and operates the solenoid valve 78, amongst other functions. A flow meter 66 in the milk flow pipe sends signals to the control unit 80 to quantify the flow of milk in the pipe. However, such signals will be altered in the event of liner slip or kick off, so the control unit must be made aware of 10 such an occurrence so that it can adjust processing of the signals that it receives in an appropriate manner.

Consider now events that occur after the onset of liner slip. As air enters the teat cup, so the pressure at the inlet port 22, and therefore in the valve chamber 20, will increase. This will urge the diaphragm 12 towards the cover 14. In this condition, the 15 diaphragm 12 will start to form a seal against the projection 48 within the cover 14, effectively dividing the control chamber 40 in two, an inner region containing the pilot tap 44 and an outer region containing the vent 50 and the sensing tap 52. Air can enter the outer region through the vent, so the pressure at the sensing tap 52 will rise.

During liner slip, the increase in pressure at the inlet port 22 is partial and non 20 constant. Therefore, the signal produced by the pressure sensor 64 is typically erratic, much as shown in Figure 5.

In the event of a teat cup being kicked off, the pressure in the valve chamber 20 will rise suddenly to close to atmospheric. This causes the diaphragm 12 to be urged firmly against the projection 48, so forming a good seal. The outer region of the 25 control chamber 40 will therefore rise to atmospheric pressure and stay there until the pilot tap 44 is disconnected from the vacuum. This produces an output from the pressure transducer 64 much as shown in Figure 6.

The rise in pressure in the outer region of the control chamber 40 is not instantaneous because it takes time for air to enter the chamber through the

( 7 restriction of the vent 50. This can prevent false detection of transient changes in the pressure in the vacuum line.

By performing signal processing on the output of the pressure sensor 64, it is possible for the control unit 80 to detect the onset of liner slip or a kick-off. The control unit 5 80 can then take appropriate action and generate appropriate alarm signals to alert an operator to the condition. It should also be noted that the operation of the sensor is not affected in variation in the absolute level of the vacuum in the system since the j same vacuum source is applied to both sides of the diaphragm.

While the above-described embodiment is incorporated into a valve, it is clear that the 10 principles of detection can be applied to a sensor that is a sensing device only or in combination with another control or detection device.;

Claims

( 8 Claims

1. A sensor for detecting loss of vacuum in a milking system, the sensor 5 comprising a diaphragm a first side of which is for connection to a milk flow line at a pressure below atmospheric pressure and the second side of which is for connection to a vacuum line, in which variation in the pressure across the diaphragm causes movement in the diaphragm, such movement causing a variation in output of the sensor.

10 2. A sensor according to claim I in which the output of the sensor is constituted by variable air pressure in an output line.

3. A sensor according to claim 2 in which the air pressure is variable between a vacuum level and atmospheric.

4. A sensor according to claim 2 or claim 3 further comprising a pressure 15 transducer connected to the output line for converting the pressure in the line to an electrical output signal.

5. A sensor according to any preceding one of claims 2 to 4 in which the diaphragm acts as a valve to open or close a flow passage between the output line and the vacuum line.

20 6. A sensor according to claim 5 in which, in the event that such a flow passage is open, the pressure sensed by the transducer is approximately that in the vacuum line.

7. A sensor according to claim 5 or claim 6 in which, in the event that the flow passage is closed, the pressure output may rise towards atmospheric.

25 8. A sensor according to any preceding claim in which the diaphragm is the diaphragm of a flow control valve.

( 9 9. A sensor according to claim 8 in which the flow control valve is a pilot-

operated diaphragm valve.

10. A sensor according to claim 8 or claim 9 being a converted preexisting flow control valve.

5 1 1. A sensor according to any one of claims 8 to 10 in which the flow control valve is suitable for connection in a milk flow line to control flow of milk and air through the pipe. i 12. A sensor for detecting loss of vacuum in a milking system substantially as herein described with reference to the accompanying drawings.

10 13.A system for detecting leakage of vacuum in a milking system comprising a sensor according to any preceding claim and a processor for processing the output of the sensor.

14. A system according to claim 13 in which signals from the sensor are analysed to determine the cause of the loss of vacuum.

15 15. A system according to claim 14 in which the analysis can identify at least a condition of liner slip or kick-off.

16. A milking installation comprising a sensor according to any one of claims I to 12 connected between a milk flow line and a vacuum line.

17.A milking installation according to claim 16 further comprising a milk flow 20 meter in the milk flow line, processing of signals from the meter being modified in response to signals output by the sensor.

18. A milking installation according to claim 16 or claim 17 further comprising a system according to any one of claims 13 to 15.

Amendments to the claims have been filed as follows Claims 5 1. A sensor for detecting loss of vacuum in a milking system, the sensor comprising a diaphragm a first side of which is for connection to a milk flow line at a pressure below atmospheric pressure and the second side of which is for connection to a vacuum line, in which variation in the pressure across the diaphragm causes movement in the diaphragm, such movement causing a 10 variation in an output signal of the sensor, in which the output signal of the sensor is constituted by variable air pressure in an output line, the output pressure being variable between a vacuum level and atmospheric.

2. A sensor according to claim I further comprising a pressure transducer connected to the output line for converting the pressure in the output line to 15 an electrical output signal.

3. A sensor according to claim I or claim 2 in which the diaphragm acts as a valve to open or close a flow passage between the output line and the vacuum line. | 4. A sensor according to claim 3 in which, in the event that such a flow passage is open, the pressure sensed by the transducer is approximately that in the 20 vacuum line.

5. A sensor according to claim 3 or claim 4 in which, in the event that the flow passage is closed, the pressure output may rise towards atmospheric.

6. A sensor according to any preceding claim, in:.hich the diaphragm is the diaphragm of a flow control valve.

25 7. A sensor according to claim 6 in which the flow control valve is a pilot- I operated diaphragm valve.

8. A sensor according to claim 6 or claim 7 being a converted preexisting flow control valve.

9. A sensor according to any one of claims 6 to 8 in which the flow control valve is suitable for connection in a milk flow line to control flow of milk and air 5 through the pipe.

10. A sensor for detecting loss of vacuum in a milking system substantially as herein described with reference to the accompanying drawings.

11. A system for detecting leakage of vacuum in a milking system comprising a sensor according to any preceding claim and a processor for processing the 1() output of the sensor.

12. A system according to claim I I in which signals from the sensor are analysed to determine the cause of the loss of vacuum.

13. A system according to claim 12 in which the analysis can identify at least a condition of liner slip or kick-off.

15 14. A milking installation comprising a sensor according to any one of claims I to 1 Reconnected between a milk flow line and a vacuum line.

15.A milking installation according to claim 14 further comprising a milk flow meter in the milk flow line, processing of signals from the meter being modified in response to signals output by the sensor.

20 16. A milking installation according to claim 14 or claim 15 further comprising a pi system according to any one of claims I I to 13. | 50.