EP1370798A1

EP1370798A1 - A device for supplying a compressed gas to a conduit in order to transport milk in the conduit

Info

Publication number: EP1370798A1
Application number: EP02700942A
Authority: EP
Inventors: Lars Wase
Original assignee: DeLaval Holding AB
Current assignee: DeLaval Holding AB
Priority date: 2001-03-02
Filing date: 2002-02-25
Publication date: 2003-12-17
Also published as: WO2002070944A8; SE0100721D0; WO2002070944A1

Abstract

The invention relates to a device for supplying a compressed gas to a conduit (3) for transporting milk in the conduit (3). The device comprises at least a second part (10b) of a passage (10), which passage (10) extends from a control valve (11) to the conduit (3), a venting valve (12) arranged to vent at least the second part (10b) of the passage when the control valve (11) is in a closed position and a nonreturn valve (15) having an outlet for the second part (10b) of the passage (10) and being arranged to allow a gas flow from the second part (10b) of the passage to the conduit (3) when the control valve (11) is positioned in an open position. The nonreturn valve (15) comprises a sealing member (26), which has elastic properties and is provided across said outlet in a pre-stressed state.

Description

A device for supplying a compressed gas to a conduit in order to transport milk in the conduit

THE BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention relates to a device for supplying a compressed gas to a conduit for transporting milk in the conduit, wherein the device comprises at least a second part of a passage, which passage extends from a control valve to the conduit, wherein the control valve is adjustable between an open and a closed position in order to control the supply of the compressed gas to the conduit, a venting valve arranged to vent at least the second part of the passage when a control valve is in a closed position and a nonreturn valve having an outlet for the second part of the passage and being arranged to allow a gas flow from the second part of the passage to the conduit when the control valve is in an open position.

Such devices are, for example, used in milking arrangements for transporting milk in a milk conduit to a milk tank. Such devices often comprise a relatively expensive venting valve and a nonreturn valve. The venting valve is often a magnetic valve. The function of such a magnetic valve is not reliable if the magnetic valve is subjected to water. Since the venting valve in such a milk-transporting device usually is placed at a low level above the floor, the magnetic valve will often be subjected to water during cleaning and flushing processes. For hygienic reasons, it is very important that milk in the milk conduit does not penetrate into the valve mechanism, via the nonreturn valve. Consequently, the nonreturn valve must have a sealing function of a high quality. Therefore, relatively complicated and expensive nonreturn valves have been used in such milk transporting devices.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device for supplying a compressed gas to a conduit for transporting milk in the conduit, which device is inexpensive to manufacture at the same time as it comprises a nonreturn valve with a sealing function of a high quality preventing penetration of the milk into the valve mechanism.

This object is achieved by the initially mentioned device, which is characterised in that the nonreturn valve comprises a sealing member, which has elastic properties and is provided across said outlet in a pre-stressed state. Since the sealing member has elastic properties and is pre-stressed, it fits tightly against the outlet of the passage, when the control valve is closed. The elastic properties and the pre-stressed state of the sealing member result in that leakage of the milk into the outlet of the passage is prevented in an effective manner. The elastic sealing member prevents a gas flow from the outlet to the conduit until the gas pressure in the passage exceeds a value corresponding to the pre-stressing of the sealing member. However, such a pressure in the passage is obtained substantially immediately, when the control valve is open and the passage is connected to the compressed gas source. In this state, the compressed gas expands the sealing member such that the compressed gas is able to flow out of the outlet. The pressure in the passage and said gas flow prevents milk from penetrating into the passage. Such an elastic sealing member may have a simple construction and the nonreturn valve is inexpensive to manufacture. According to a preferred embodiment of the invention, said outlet of the passage is provided in a branch conduit connected to the conduit. Thereby, the nonreturn valve is positioned in a protected location from which it is possible to supply the pressured gas to the conduit. Advantageously, said outlet of the passage is provided in a portion of the nonreturn valve, which protrudes into the conduit or into the branch conduit. The protruding portion may protrude into the branch conduit in an axial direction of the branch conduit. With such an arrangement of the protruding portion, a gas flow may preferably be initiated at a centre surface of the branch conduit. Thereby, the compressed gas initiates a pressure distribution resulting in an essentially uniform motion of the milk in the conduit. Alternatively, the protruding portion may protrude into the conduit in a radial direction of the conduit.

According to another preferred embodiment of the invention, said outlet is located in a groove extending along a surface of the protruding portion and in that the sealing member is provided in the groove. Such a groove simplifies a correct positioning of the sealing member across the outlet of the passage and further increases the sealing properties of the sealing member. Preferably, said groove and sealing member are annular and extend around the protruding portion. Such a sealing member may be an o-ring manufactured of an elastomer material and positioned in the annular groove. Preferably, the sealing member has in the pre-stressed state a contact surface with substantially the whole surface of the groove. Consequently, the sealing member entirely fills the groove and makes it substantially impossible for the milk to penetrate past the sealing member into the outlet of the passage.

According to another preferred embodiment of the invention, the nonreturn valve comprises a substantially disc-shaped portion from which the protruding portion extends. Such a disc-shaped portion, may have a front surface, enabling positioning of the valve body at an end of the branch conduit. The protruding part may here extend in a direction substantially perpendicular to a plane extending through the disc-shaped portion.

According to another preferred embodiment of the invention, said venting valve comprises a valve body, which is arranged to be displaced to a first position, when the control valve is in the closed position, in which first position the valve body exposes an opening of a venting duct extending between the second part of the passage and a surrounding atmosphere at the same time as it closes a connection between the second part of the passage and a first part of the passage. In this state, the open venting duct decreases the pressure in the second part of the passage and the sealing member contracts such that it covers the outlet and prevents milk from penetrating into the passage. The volume of the second part of the passage preferably constitutes only a small portion of the total volume of the passage. Thereby, the air pressure in the second part of the passage may be decreased very quickly and the sealing member contracts towards the outlet in a correspondingly quick manner. Consequently, the risk that milk penetrates into the passage during the adjustment of the control valve from an open to a closed position is minimal. Preferably, said venting valve comprises a spring, which tends to displace the valve body towards said first position. In some cases, the pressure difference between the gas in the second part of the passage and the first part of the passage is not enough to displace the valve body to the first position, when the control valve is adjusted to a closed position. The use of the spring guarantees this function. If the sealing member is damaged or broken, the closing of the connection between the first and second part of the passage prevents penetration of milk into the first part of the passage. When the second part of the passage is filled with milk, which may be a result of a damaged or broken sealing member, the milk flows out through the venting duct. The out flowing milk indicates clearly that the sealing member has to be changed.

According to another preferred embodiment of the invention, said valve body may be arranged to be displaced to a second position, when the control valve is open, in which position the valve body closes the venting duct and opens the connection between the second part of the passage and the first part of the passage. In this state, compressed gas of a relatively high pressure flows from the compressed gas source through the passage, where it passes the valve body, and out through the outlet of the nonreturn valve.

Advantageously, said gas is air. Air is the cheapest gas to use. The device may be used in a milking arrangement for the transportation of milk in a conduit to a milk tank.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now to be explained more closely by means of a preferred embodiment, which is disclosed as an example, and with reference to the attached drawings.

Fig 1 shows schematically a milking arrangement comprising a device according to the invention and

Fig 2 shows the venting valve and the nonreturn valve of a device according to the invention.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Fig 1 shows a part of a milking arrangement comprising a device according to the invention. The milking arrangement comprises a milk receiver 1 , which is arranged to receive milk from at least one milking machine, which is not shown in Fig 1. A pump 2 transports the milk from the milk receiver 1 via a conduit 3 to a milk tank 4. The pump 2 is used to transport the milk a relatively short distance from the milk receiver 1 into the milk conduit 3 and past a nonreturn valve 5. The milk conduit 3 comprises a cut-off valve 6, which enables closing of the milk conduit 3.

In order to transport the milk in the conduit 3 from the nonreturn valve 5 to the milk tank 4, compressed air is supplied to the conduit 3. The compressed air is supplied at a point 8 of the milk conduit 3. This point 8 is located immediately downstream of the nonreturn valve 5. Consequently, a higher pressure is achieved in the milk conduit 3 at said point 8 than at an outlet of the conduit 3 in the milk tank 4. This pressure difference provides the transportation of the milk located in the conduit 3 in a direction towards the milk tank 4.

The compressed air is supplied from a compressed air source 9. The compressed air source 9 comprises, for example, a pressure vessel containing compressed air of a constant pressure of about 6 bar. An air compressor maintains the constant air pressure in the pressure vessel. A control valve 1 1 is located close to the compressed air source 9. An air passage 10 extends from the control valve 1 1 to the milk conduit 3. The control valve 1 1 is adjustable between an open and a closed position in order to allow or prevent the supply of compressed air to the milk conduit 3. The adjustment of the control valve 1 1 may be initiated by signals from a control panel manoeuvred by an operator. A device comprising a venting valve 12 is provided after the control valve 1 1 in the air passage 10. The venting valve 12 is arranged to allow a quick pressure drop in a second part 10b of the air passage 10, when the control valve is adjusted to a closed position. The venting valve 12 adjusts the pressure in the second part 10b of the air passage 10 to the surrounding atmospheric pressure by opening a venting duct 14. The device compπses also a nonreturn valve 15, which is provided at the end of the air passage 10. The nonreturn valve 15 is arranged to allow a supply of compressed air to the milk conduit 3 when the control valve 1 1 is open and to prevent that milk penetrates into the air passage 10, particularly when the control valve is closed. The nonreturn valve 15 allows compressed air to pass to a branch conduit 16 connected to the milk conduit 3.

Fig 2 shows the construction of the venting valve 12 and the nonreturn valve 15 in more detail. The venting valve 12 comprises a valve body 17 manufactured of a rubber material. The valve body 17 is displaceable between a first position, which is shown in Fig 2, and a second position, in which the valve body 17 is located against an end portion of the venting duct 14. The valve body 17 is displaced by a spring 18 towards the first position. In the first position, the valve body 17 closes the connection between the second part 10b of the air passage 10 and the first part 10a of the air passage 10. The valve body 17 exposes, in the first position, an opening of a venting duct 14 extending between the second part 10b of the air passage 10 and a surrounding atmosphere. Thereby, the surrounding atmosphere pressure is maintained in the second part 10b of the passage 10 when the control valve 1 1 is closed. If the control valve 1 1 is adjusted to the open position, the compressed air source 9 supplies air of a high pressure to the air passage 10. The supplied air moves the valve body 17 to the second position. In the second position, the valve body 17 opens the connection between the second part 10b of the passage 10 and the first part 10a of the passage 10. In the second position, an upper surface of the valve body 17 closes an opening of the venting duct 14. Air of high-pressure flows past the valve body 17 and provides a high pressure in the second part 10b of the passage 10.

A tubular sleeve 19 connects the venting valve 11 and the nonreturn valve 15. The tubular sleeve 19 has external threads which engage corresponding threads arranged internally in channels 13a, b of the venting valve 1 1 and the nonreturn valve 15 respectively. The channels 13a, b together form the second part 10b of passage 10. The nonreturn valve 15 has a substantially disc-shaped portion 20 with a front surface. The nonreturn valve 15 is connected at said surface to an end of the branch conduit 16 having a corresponding surface. A sealing member 21 is arranged between said surfaces and a clamping member 22 is arranged to fixedly connect said surfaces. The nonreturn valve 15 comprises a protruding portion 23, which protrudes from the disc-shaped portion 20 in an axial direction inside the branch conduit 16. Two ducts 24 extend in diametrically opposite directions from an end of the channel 13b extending in the protruding portion 23. The ducts 24 have outlets located in an annular groove 25 extending around a surface of the protruding portion 23. An annular sealing member 26 is provided in the groove 25. The annular sealing member 26 is arranged in a pre-stressed state in the groove 25. The annular sealing member 26 has substantially the same cross section diameter in the pre-stressed state as the groove 25.

When the control valve 1 1 is adjusted to an open position, the compressed air source 9 supplies air of high pressure to the air passage 10. The supplied air lifts the valve body 17 against the tension of the spring 18 to the second position. An airflow passes at the sides of the valve body 17 and into the second part 10b of the air passage 10. When a specific air pressure is reached in the second part 10b of the air passage 10, the compressed air has expanded the sealing member 26 such that compressed air is allowed to flow through the outlet of the ducts 24 and pass the expanded sealing member 26. The compressed air is preferably supplied to a substantially central part of the branch conduit 16. The compressed air increases the pressure in the conduit 3 at point 8. Thereby, a higher pressure is provided at the point 8 than at the outlet of the milk conduit 3 in the milk tank 4, in which the pressure substantially corresponds to the pressure of the surrounding atmosphere. The pressure difference moves the milk in the milk conduit 3 from the point 8 in the milk conduit 3 towards the milk tank 4. The compressed air is supplied to the milk conduit 3 having a pressure such that the risk of milk penetration into the air passage 10 is substantially eliminated. Even if milk drops should penetrate into the ducts 24, the airflow in the ducts 24 blows it out.

When the transportation of milk to the milk tank 4 is to be ended, an operator adjusts the control valve 1 1 to a closed position. The supply of compressed air from the compressed air source 9 to the air passage 10 is thereby stopped. The valve body 17 is displaced to the first position by the spring 18. In the first position, the valve body 17 closes the connection between the second part 10b of the air passage 10 and the first part 10a of the air passage 10. At the same time, it exposes the opening of the duct 14. The second part 10b of the air passage 10 quickly obtains the surrounding atmosphere pressure. During the pressure drop in the second part 10b of the passage 10, the sealing member 26 is contracted in the groove 25. The sealing member 26 thus quickly closes the outlet of the air passage 10. The risk that milk penetrates into the air passage 10 in this state is thereby eliminated.

The venting valve 12 and the nonreturn valve 15 both have a simple mechanical construction. Consequently, they may be manufactured at a low cost. The nonreturn valve 15 has a sealing construction, which in an effective manner prevents penetration of milk into the air passage 10.

In order to perform a cleaning operation of the conduit 3, a washing liquid and a rinsing liquid have to be transported through the conduit 3 at suitable occasions. In this case, the pump 2 and the device for the supply of the compressed gas may be used for the transportation of the washing liquid and the rinsing liquid in the conduit 3. Thereby, no special transport device needs to be used for the cleaning operation of the conduit 3. The invention is not limited to the embodiment described above but may be varied and modified within the scope of the claims.

Claims

1 . A device for supplying a compressed gas to a conduit (3) for transporting milk in the conduit (3), wherein the device comprises at least a second part ( 10b) of a passage (10), which passage (10) extends from a control valve (1 1 ) to the conduit (3), wherein the control valve ( 1 1 ) is adjustable between an open and a closed position in order to control the supply of the compressed gas to the conduit (3), a venting valve (12) arranged to vent at least the second part (10b) of the passage when the control valve (1 1 ) is in a closed position and a nonreturn valve (15) having an outlet for the second part (10b) of the passage (10) and being arranged to allow a gas flow from the second part (10b) of the passage to the conduit (3) when the control valve (1 1 ) is positioned in an open position, characterised in that the nonreturn valve (15) comprises a sealing member (26), which has elastic properties and is provided across said outlet in a pre-stressed state.

2. A device according to claim 1 , characterised in that said outlet is provided in a branch conduit (16) connected to the conduit (3).

3. A device according to claim 1 or 2, characterised in that said outlet of the passage (10) is provided on a portion (23) of the nonreturn valve (15), which protrudes into the conduit (3) or into the branch conduit (16).

4. A device according to claim 3, characterised in that said outlet is located in a groove (25) extending along a surface of the protruding portion (23) and in that the sealing member (26) is provided in the groove (25).

5. A device according to claim 4, characterised in that said groove (25) and sealing member (26) are annular and extend around the protruding portion (23).

6. A device according to claim 4 or 5, characterised in that the sealing member (26) in the pre-stressed state has a contact surface with substantially the whole surface of the groove (25).

7. A device according to any one of the preceding claims 3-6, characterised in that the nonreturn valve (15) comprises a substantially disc-shaped portion (20) from which the protruding portion (23) extends.

8. A device according to any one of the preceding claims, characterised in that said venting valve ( 12) comprises a valve body (17), which is arranged to be displaced to a first position when the control valve (1 1 ) is in the closed position, in which first position the valve body (17) exposes an opening of a venting duct (14) extending between the second part (10b) of the passage and a surrounding atmosphere at the same time as it closes a connection between the second part (10b) of the passage and a first part (10a) of the passage.

9. A device according to claim 8, characterised in that said venting valve (12) comprises a spring (18), which tends to displace the valve body (17) in a direction towards said first position.

10. A device according to claim 8 or 9, characterised in that said valve body (17) is arranged to be displaced to a second position when the control valve (11 ) is open, in which position the valve body (17) closes the opening of the venting duct (14) and opens the connection between the second part (10b) of the passage and the first part (10a) of the passage.

1 1. A device according to any one of the preceding claims, characterised in that said gas is air.

12. A milking arrangement comprising a device according to any one of the preceding claims for transporting milk in a conduit (3) to a milk tank (4).

13. A milking arrangement according to claim 12, characterized In_. that it comprises a compressed gas source (9) and a control valve (1 1 ).