AU448552B2 - Liquid-and-air mixing gear pump - Google Patents

Description

38.40 3 /7 This invention relates to gear pumps for feeding liquid

and air mixes, and in particular to a gear pump of the kind which comprises a pump casing, a pair of interm shing gears

rotatably mounted inside the casing, a liquid intake duct

terminating at a liquid intake port disposed in the casing

at a position where the gears begin to move out of mesh, and

for each gear an air intake port disposed to supply air to

the teeth of the gear.

A numD of the above kind is described in more detail in /tho Tnitc i AKil ctatgc 4,6 300. Pc-tot aplication carial 17. 051877

It has been found that, during the stopping time of the

said type of pump, the pressure existing downstream of the

pump tends to cause a small amount of foamy liquid- and-air

emulsion to flow out of both air intake ports. This foam

flows down into the liquid feed vat and, in the long run, an

accessively great amount of foam comes to be collected in said

vat.

The principal object of the present invention is to

overcome the disadvantages of pumps of the said type in a

convenient and economical manner.

With the above stated object in view a gear pump for

feeding liquid-and-air mixes, which comprises a liquid intake

port upstream of the region in which the pump gears are in

mesh, a liquid-and-air emulsion delivery port downstream of

the region in which the pump gears are in mesh, and two air

intake ports, one for each one of the pump gears disposed in

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38.403 /72 the gear path between the li<liid intake port and the emulsion

delivery port, is characteri:ced in that said air intake ports are in cormunicaticn with the ,itmosphere through a foam

collecting tank or chamber.

In the arrangement stat(d the amount of foam flowing out

of said ports when the pump is inoperative is collected in the tank or chamber and. upon tho pump again becoming operative

this foam is taken up by the pump before it again commences to take in air.

Since the amount of feed-back foam is relatively small each time the pump is stoppod, the said tanks or chambers may be of small volume, and may be formed in the pump casing it- self, in form of vertical, or relatively vertically extending cylindrical ducts each communicating at their lower end with

an air intake port, and at the upper end with the atmosphere.

Reference will now be mide to the accompanying drawings

illustrating a pump constructed in accordance with the present

invention. In these drawin:

Figure 1 is a front view of the emulsifying pump according to the invention:

Figure 2 is a. cross-section of the same pump; and

Figure 3 is a view with parts in section of the cover member of the pump as shown in Figure 1.

As illustrated in the dr!.-.wings, the pump as shown

comprises a casing 1 housing the gears 2.

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38.403/72 The said casing I is closed in its front face by a cover 3 carrying the liquid mix intake pipe 4, the liquid-and-air emulsion delivery pipe 5, and the air intake ports 6 and 7.

In the prior art pumps of the kind referred to above, the said ports directly communicate with the atmosphere. During the periods of time in which the pump is temporarily inoperative, the downstream pressure within the pump promotes the outflow of a certain amount of foam from the air intake ports. The said amount of foam is of relatively small volume. However, as the pump is freauently stopped, and in certain machines this stopping takes place after the frequent dispens- ing of a few cubic centimeters of product, the total amount of foam formed during one working day of the machine becomes considerable. This foam is collected in the (not shown) underlying liquid mix feed vat. The accumulation of foam in said vat is objectionable for many reasons. Particularly, the said foam, by floating, renders the appearance of the product in the feed vat rather unattractive. Additionally, the said foam is not so readily refrigerated as the liquid, since the air contained therewithin tends to render same heat insulating. Therefore, the foam is more likely to be subject to alterations which migIt influence the taste of the whole product.

According to the present invention, in order to obviate the above mentioned disadvanta-es, upstream of the air intake norts, small tanks or chamrbers are provided which are

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38403/72

adapted to contain the amounts of foam being produced at each stoppage of the pump. As shown in the drawings, and as better shown in'Figure 3 thereof, the said tanks or chambers are conveniently in the form of two ducts 8 and 9 formed in the body of the pump cover 3, which, from ports 6, 7, extend upwardly through the remaining part of said cover, and are open to, and communicate with the atmosphere.

The said ducts are more than sufficient to contain the amount of foam being formed at every stoppage of the pump, which amount, whenever the pump is again set in operation, is again drawn through ports 6 and 7, before the said ports will begin again to draw in air to be emulsified with the liquid being drawn through pipe 4.

Of course the present invention is not limited to the shown embodiment and although the said small tanks have been shomw as formed in the cover body itself, it is understood that the same might be similarly obtained by providing independent tubular members to be fitted onto ports 6 and 7, or by providing any other container member to be arranged upstream of ports 6 and 7.

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Claims (1)

1. 38.403/72

   The claims defining the invention are as follows

   1. A gear pump for feeding liquid-and-air uixes, which comprises a licuid intake port upstream of the region in which the pump gears are in mesh, a liquid-and-air emulsion delivery port dowmstream of the region in which the pump gears are in mesh, and wo air intake ports, one for each one of the pump gears disposed in the gear path between the liquid intake port and the emulsion delivery port, is characterized in that said air intake ports are in com-m.uni- cation with the atmosphere through a foam collecting tank or chamber.

   2. A gear pump as claimed in claim 1 further characterized in that the said collecting chamber is formed in the pump body itself and is constituted by a vertical, or substantially vertically extending tubular duct communicating at its lower end with each of the intake ports and, at its top, with the atmosphere.

   3. A gear pump for feeding liquid-and-air mixes substantially as described and as shown in the accompanying drawings.

   D A T D D this 26th day of January, 1972

   APAW S.A. ,By its Patent Attorneys: CALLIiNAII LTTD 1WTON

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   38.40372

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