MIXING DEVICE

Abstract

The invention relates to a mixing chamber in which a first liquid comes into contact with a second liquid, and a gas injection device designed to inject a gas into the mixing chamber, wherein the gas injection device comprises: a gas source to provide the gas at a predetermined pressure, and a metering unit to limit the gas provided by the gas source to a predetermined flow rate, wherein the metering unit is in contact with the mixing chamber on a gas outlet side of the metering unit, wherein the gas outlet side of the metering unit comprises an elongated gap, wherein the gas passes out of the metering unit into the mixing chamber via the elongated gap, and wherein the gas passes out of the metering unit into the mixing chamber.

Claims

1. A mixing device for mixing liquids with gas, comprising: a mixing chamber in which a first liquid comes into contact with a second liquid, and a gas injection device designed to inject gas into the mixing chamber, wherein the gas injection device comprises: a gas source to provide the gas at a predetermined pressure, and a metering unit to limit the gas provided by the gas source to a predetermined flow rate, wherein the metering unit is in contact with the mixing chamber on a gas outlet side of the metering unit, wherein the gas outlet side of the metering unit comprises an elongated gap, and wherein the gas passes out of the metering unit into the mixing chamber via the elongated gap.

2. The mixing device of claim 1, wherein the metering unit is formed from two planar elements coupled to one another.

3. The mixing device of claim 2, wherein the planar elements abut one another substantially over their entire surface.

4. The mixing device of claim 3, wherein the abutting surfaces of the planar elements have a mean surface roughness (Ra) of at most Ra 0.1.

5. The mixing device of claim 2, wherein the planar elements comprise ring discs and wherein the gas outlet side of the metering unit is formed on an inside of the ring discs.

6. The mixing device of claims 2, wherein the planar elements are made of one or more of metal, of ceramic, or of polytetrafluoroethylene.

7. The mixing device of claims 2, wherein the planar elements are made of a porous material.

8. The mixing device of claims 1, wherein the metering unit has a flow rate of at most 100 cubic centimeters per second (cm.sup.3/s) at a pressure of approximately 20 bar.

9. The mixing device of claim 1, wherein the mixing device further comprises a stirring means to mix the first liquid, the second liquid, and the added gas with one another.

10. The mixing device of claim 9, wherein the stirring means is operable at a rotational speed of, at most, 10,000 rounds per minute (rpm).

11. The mixing device of claim 1, wherein the gas comprises air.

12. The mixing device of claim 1, wherein the first liquid has a viscosity of 100 millipascal seconds (mPa.Math.s) to 500,000 mPa.Math.s.

13. The mixing device of claim 1, wherein the second liquid has a viscosity of 20 millipascal seconds (mPa.Math.s) to 200,000 mPa.Math.s.

14. The mixing device of claim 1, wherein one or more of (a) the first liquid comprises polyol or silicone A or (b) the second liquid comprises isocyanate or silicone B.

15. The mixing device of claim 1, wherein the predetermined pressure of the gas provided by the gas source is within a range of 1 bar to 30 bar.

16. The mixing device of claim 6, wherein the metal comprises steel or aluminium.

17. A mixing device for mixing liquids with gases, comprising: a mixing chamber in which a first liquid comes into contact with a second liquid, and a gas injection device designed to inject a gas into the mixing chamber, wherein the gas injection device comprises: a gas source to provide the gas at a predetermined pressure, and a metering unit to limit the gas provided by the gas source to a predetermined flow rate, wherein the metering unit is in contact with the mixing chamber on a gas outlet side of the metering unit, and wherein the gas passes out of the metering unit into the mixing chamber.

18. The mixing device of claim 17, wherein the gas outlet side of the metering unit comprises an elongated gap, and wherein the gas passes out of the metering unit into the mixing chamber via the elongated gap.

19. A mixing device for mixing liquids with gases, comprising: a mixing chamber in which a first liquid comes into contact with a second liquid, and a gas injection device designed to inject a gas into the mixing chamber, wherein the gas injection device comprises: a gas source to provide the gas at a predetermined pressure, and a metering unit to limit the gas provided by the gas source to a predetermined flow rate, wherein the metering unit is in contact with the mixing chamber on a gas outlet side of the metering unit, wherein the metering unit is formed from two planar elements coupled to one another, wherein the planar elements comprise ring discs, and wherein the gas outlet side of the metering unit is formed on an inside of the ring discs, and wherein the gas passes out of the metering unit into the mixing chamber.

20. The mixing device of claim 19, wherein the gas outlet side of the metering unit comprises an elongated gap, and wherein the gas passes out of the metering unit into the mixing chamber via the elongated gap.

Description

[0031] In FIG. 1, a mixing device according to the invention is generally denoted with reference sign 10. The mixing device 10 comprises a housing 12 in which an element 14 extending in a main flow direction A of the liquids flowing through the mixing device 10 is arranged. The element 14 forms an outer wall of a mixing chamber 16. A first liquid is introduced into the mixing chamber 16 at a first entry point 18 into the mixing chamber 16. A second liquid is introduced into the mixing chamber 16 at a second entry point 20.

[0032] The respective sources or reservoirs of the first and the second liquid are arranged in a superordinate assembly (not shown), which is arranged upstream in relation to the main flow direction A and to which the mixing device 10 can be connected via a fastening device 22 such as a fastening nut 22.

[0033] A first planar element 24 is arranged adjacent to the entry points 18 and 20 of the two liquids, the lower side 26 of which element is sealed off with respect to a radially outer side by a seal 28 cooperating with the first planar element 24 and the housing 12. In this case, the first planar element 24 is designed substantially as a ring disc.

[0034] A radially inner portion of the first planar element 24 abuts a second planar element 30 which is formed by an annular portion of the element 14 delimiting the mixing chamber 16.

[0035] A gap 32 is formed between the first planar element 24 and the second planar element 30, through which gap gas can enter the mixing chamber 16 in a defined manner. To provide gas on the radially outer side of the gap 32, an annular groove 34 surrounding the gap is provided, which annular groove is formed in the first planar element 24. On the side shown on the right in FIG. 1, the annular groove 34 is in fluid communication with bores 38 which connect the annular groove 34 to an outer side surrounding the housing 12, such that a gas source 40 can provide gas to the annular groove 34 at a predetermined pressure.

[0036] In this way, the gap 32 formed by the first planar element 24 and the second planar element 30 forms a metering unit 42 which can introduce gas, such as air, provided by the gas source 40, into the mixture of liquids around the entire outer circumference of a flow of liquid mixture consisting of the first or second liquid which has been introduced into the mixing chamber 16 at entry points 18 and 20. The metering unit 42 and the gas source 40 can together be considered to be a gas injection device 36.

[0037] By correspondingly producing or processing a surface roughness of the surfaces of the first planar element 24 and the second planar element 30 that are in contact with one another, an amount of gas passing through the gap 32 and/or a size of the gas bubbles entering from the gap 32 into the liquid mixture which is located in the mixing chamber 16 can be adjusted very precisely.

[0038] A stirring means 44 is arranged centrally in the mixing chamber 16, which stirring means is designed to mix the first liquid, the second liquid and the gas with one another. As can be seen in FIG. 1, the metering unit 42 or the gap 32 is arranged directly adjacent to the entry points 18 and 20 of the first and second liquid. In this way, a conveying path from a portion of the mixing device 10 at which the first liquid, the second liquid and the gas are initially mixed with one another to a dispensing end 46 of the mixing device 10 can be maximised, whereby the outcome of mixing the components mentioned above can be improved.

[0039] The stirring means 44 has grooves 48 on its outer circumference, which can improve gripping of the gas-liquid mixture and thus mixing of the components.

[0040] The mixing device 10 further comprises a closure unit 50 which comprises a closure element 52 which can interact with the stirring means 44 in such a way that a release of gas-liquid mixture from the dispensing end 46 of the mixing device 10 can be prevented. To close the closure unit 50, a fluid at a predetermined pressure can be introduced into a space 54 which is provided in the housing 12 of the mixing device 10, causing a lifting device 56 of the closure unit 50 to move in an upward direction in FIG. 1 in order to bring the closure element 52 closer to the stirring means 44, i.e. to close the dispensing end 46.