WO2008044253A1

WO2008044253A1 - Transmission apparatus in homogeniser or high pressure piston pump

Info

Publication number: WO2008044253A1
Application number: PCT/IT2006/000725
Authority: WO
Inventors: Marco Gandini; Simone Grandi
Original assignee: Gea Niro Soavi S.P.A.
Priority date: 2006-10-10
Filing date: 2006-10-10
Publication date: 2008-04-17
Also published as: EP2082134B1; ATE458145T1; DE602006012384D1; EP2082134A1; DK2082134T3

Abstract

A transmission apparatus (1), in homogeniser or high pressure piston pump, comprises a fixed body (7) housing a rotating crankshaft (10), a motor (3) able to actuating said crankshaft through transmission means, a reducer (4), interconnected between the shaft (10) and said transmission means, and means for fastening the reducer to said body, able to prevent oscillations of the reducer relative to the crankshaft, achieving a rigid cylindrical coupling between the reducer and the fixed body (7).

Description

TRANSMISSION APPARATUS IN HOMOGENISER OR HIGH PRESSURE PISTON PUMP

TECHNICAL FIELD AND BACKGROUND ART. The present invention relates to a transmission apparatus, in a homogeniser or high pressure piston pump, said apparatus comprising: a fixed body housing a rotating crankshaft, a motor able to actuate the crankshaft, a reducer interconnected between said shaft and said transmission means. The present invention further relates to a technical solution for the assembly of a transmission apparatus, for a homogeniser or high pressure piston pump.

Within the field of the treatment of high pressure fluids (indicatively, from 150 to 1,500 bar), in particular with regard to applications involving emulsion micronisation, stabilisation of spills and also the controlled cellular rupture / break-up of a fluid, apparatuses known as homogenisers are frequently used. Such apparatuses generally comprise a piston pump part, used to achieve the reciprocating motion of the pumping pistons, synchronous and mutually offset by an angle 360°/« where n is the number of the pistons. In particular, the Italian patent application PR99A000045 discloses a homogeniser comprising an adjustable valve (called homogenising valve), which accomplishes the forced passage of the fluid to be treated from a high pressure area to a low pressure area, and a transmission apparatus, in turn comprising a high pressure piston pump, an electric motor which drives the pump and a reducer connected between the motor and the pump. Said reducer is necessary to reduce the rotation rate of the motor (generally about 1500 ÷ 1800 revolutions per minute) to a speed that is useful for the operation of the pump (about 150 ÷ 180 revolutions per minute). Typically, the reducer is of the type with parallel axes and it achieves a reduction ratio of about 1:5, whilst a further reduction of said rotation rate (about 1 :2) is achieved by the means for transmitting motion from the motor to the reducer, generally comprising a system of multiple belts with pulleys. The pump is provided with a crankshaft, mounted on a fixed pump body, that through a classic piston rod / crank / cross head mechanism allows the reciprocating motion of the n pumping pistons that move and compress the fluid within the process part of the machine. In known solutions, the connection between the reducer, the pump and the motor takes place according to a fastening / assembly technique called "pendulum-like". Said technique provides for keying the reducer (in particular, the slow shaft of the reducer) directly on a projection of the crankshaft of the pump and connecting, by means of a belt and pulley system, the fast shaft of the reducer to the motor. In this way, the reducer is movable relative to the pump body, because it can rotate around the axis defined by the crankshaft. This possibility of rotating the reducer around the crankshaft is exploited when assembling the transmission apparatus, to apply the necessary tension to the belt system in order to transmit the driving torque from the motor to the crankshaft. In known solutions, the distance between the motor and pump body is fixed, therefore a rotation of the reducer around its own slow shaft (connected to the crankshaft) entails a change in the distance between the fast shaft of the same reducer and the motor, starting from the assumption that the reducer is of the kind with non coaxial shafts. The pendulum-like mounting of the reducer also provides for the presence of a reaction arm, which fastens the reducer to a fixed frame, exerting thereon a traction force in a direction that is parallel and is opposite in direction relative to the tension of the belt, to counter-balance it.

The pendulum-like mounting of the reducer is convenient during the assembly stage, because the belt is tensioned acting on the reaction arm, whose length can be varied. However, said known technical solution entails some disadvantages, because it introduces unwanted stresses and oscillations in the transmission apparatus. In the first place, it should be noted that the weight of the reducer, mounted in overhang on the end of the shaft, is fully borne by the crankshaft and by its bearings; therefore, the weight of the reducer generates a flexing moment on the crankshaft.

Moreover, the fact that the tension force of the belts and the reaction discharged by the reaction arm and their components act on two different, albeit parallel, planes, produces on the body of the reducer a torque characterised by an arm equal to the distance between the two parallel planes of action of the forces (in turn identified by the axis of the tension of the belts and by the axis of the reaction arm, respectively), which generates an additional flexing moment discharged on the crankshaft. Said forces entail an oscillatory motion of the reducer both relative to a plane that is orthogonal to the axis of the crankshaft, and relative to a reference plane that is perpendicular to the crankshaft, resulting in a complex oscillatory motion; moreover, said flexing moments combine with the twisting moment due to point load stresses generated by the individual pumping pistons during the compression phase, in relation to the rotation of the crankshaft, thus subjecting it to undesired stresses. Therefore, prior art technical solutions globally entail possible limitations with regard to the reliability of the transmission system. DISCLOSURE OF INVENTION. An object of the present invention is to eliminate the aforesaid drawbacks and to make available a transmission apparatus, in a homogeniser or high pressure piston pump, that is particularly rugged and reliable, within a particularly simple and economical solutions, even in situations of unforeseeable overload of the machine due to incorrect conditions of use thereof.

Said objects are fully achieved by the apparatus of the present invention, which is characterised by the content of the claims set out below and in particular in that i^ comprises means for rigidly fastening the reducer to said fixed body. An additional object of the present invention is to make available a method for assembling a transmission apparatus, in a homogeniser with high pressure piston pump, which assures ruggedness and reliability for the apparatus itself.

Said object is fully achieved by the method of the present invention, which is characterised by the content of the claims set out below and in particular in that it comprises the following steps:

- fastening a reducer, keyed on the crankshaft, rigidly to said fixed body, in order to inhibit all oscillations of the reducer relative to the crankshaft; - connecting the reducer to a motor by means of a system of transmission belts and associated pulleys;

- tensioning the transmission belts by translating the motor, said motor being movable relative to said fixed body;

- locking the motor relative to the fixed body, once tensioning is complete.

BRIEF DESCRIPTION OF DRAWINGS.

This and other characteristics shall become more readily apparent from the following description of a preferred embodiment, illustrated purely by way of non limiting example in the accompanying drawing tables, in which:

- Figure 1 shows a perspective view of a transmission apparatus according to the present invention;

- Figure 2 shows the apparatus of Figure 1, according to a different perspective; - Figure 3 shows a perspective view of an apparatus of Figure 1, open and in partial transparence;

- Figure 4 shows a view from a different perspective from Figure 3 of an apparatus of Figure 1, open and^in partial transparence;

- Figure 5 shows a section view of the apparatus of Figure 1. BEST MODE FOR CARRYING OUT THE INVENTION.

With reference to Figures 1 and 2 and I₅ the number 1 designates a transmission apparatus in a homogeniser, the number 2 designates a fixed frame supporting the transmission apparatus 1. Within said transmission apparatus 1, the reference number 3 designates an electric motor, connected to a reducer 4 by means of a system of parallel belts 5 and pulleys 6. In turn, said reducer 4 is connected to a fixed body 7. The motor 3 is originally movable relative to the frame 2, because is bears on slides 8, along which it can translate. The position of the motor 3 relative to. the frame 2 is adjusted and fastened by actuating means, constituting, in the illustrated embodiment, by a tie rod 9.

Figures 3 and 4 show the connection between the fixed body 7 and the reducer 4, the latter being shown in see-through view. The fixed body 7, integral with the frame 2, houses a crankshaft 10, of a known kind, rotating within said fixed body 7. The crankshaft 10 has an overhang portion relative to the fixed body 7. On said portion of the crankshaft 10 is keyed the reducer 4; therefore, the crankshaft 10 defines the slow shaft of the reducer which, in the illustrated embodiment, is of the type with parallel axes. The reference 11 designates a fast shaft of the reducer 4, which is set in rotation by the motor 3. The reducer 4 is originally made integral with the fixed body 7 by fastening means. Said fastening means preferably comprise a flange 12, connected to the reducer 4 by means of a plurality of screws 13a and to the fixed body 7 by means of an additional plurality of screws 13b. Therefore, the flexing moment associated to the weight of the reducer 4 and every other flexing moment associated to the tension of the belt 6 originally unloads on the fixed body 7 through the flange 12, relieving the crankshaft 10 from dangerous stresses, in particular the flexing moment generated by the torque identified by belt tension, reaction and related arm. The flange 12 constitutes a rigid connection between the reducer 4 and the fixed body 7, able to inhibit the oscillations of the reducer, thanks to the presence of a plurality of screws, which work in shear mode, positioned in such a way as to surround the shaft 10, preferably, but not exclusively, distributed uniformly.

Note also that the flange 12 for fastening the reducer 4 to the fixed body 7 must be constructed in such a way as to assure the coupling with the body 7 itself both on a surface of the fixed body 7 perpendicular to the crankshaft 10, both on a cylindrical surface coaxial with the crankshaft 10, identified on the fixed body 7, thereby achieving a cylindrical coupling between reducer and body. In this way, an optimal distribution is obtained of the stresses between the reducer 4 and the fixed body 7, which are thus rigidly bound. However, in different embodiments, the reducer 4 can be connected to surfaces of the pump body 11. that are not orthogonal to the crankshaft 10, or even to other surfaces, provided that it is rigidly fastened relative to the pump body 11 or to the frame 2, with no chance of being subjected to oscillations or vibrations.

It should also be observed that, when assembling the transmission apparatus 1, the tensioning of the parallel belt system 5, is originally accomplished by moving the motor 3; in particular the motor 3 is translated along the slides 8, away from the reducer 4, which is fixed.

The present invention also makes available a method for assembling a transmission apparatus 1, comprising a pump 7 provided with a crankshaft 10 that rotates inside a fixed body 7. Said method comprises the following steps:

- fastening a reducer, keyed on the crankshaft 10, rigidly to said fixed body, in order to inhibit all oscillations of the reducer relative to the crankshaft 10; \

- connecting the reducer 4 to a motor 3 by means of a system of transmission belts 5 and associated pulleys;

- tensioning the transmission belt 5 by translating the motor 3, said motor being movable relative to said fixed body 7; - locking the motor 3 relative to the fixed body 7, once tensioning is complete.

Said method originally enables to assemble the transmission apparatus, tensioning the transmission belts 5, without moving the reducer, which always remains rigidly fastened to the fixed body 7, i.e. integral with the frame 2. In this way, one also has the advantage of being able to use a reducer in which the slow shaft and the fast shaft are coaxial, limiting the overall bulk of the machine. Therefore, the described method assures a greater ruggedness and reliability of the transmission apparatus, because the stresses generated by the belt tensioning load are not discharged on the crankshaft 10 but on the fixed body 7, on the flange 12 and on the body of the reducer 4, by means of appropriate connecting members.

Claims

1. Transmission apparatus (1), in homogeniser or high pressure piston pump, said apparatus comprising:

- a fixed body (7) housing a rotating crankshaft (10) - a motor (3) able to actuate the crankshaft (10);

- a reducer (4) interconnected between said shaft (10) and said transmission means; characterised in that it comprises means for rigidly fixing the reducer to said fixed body.

2. Apparatus as claimed in claim 1, characterised in that said means for fastening the reducer (4) are applied to at least one surface of said pump body (11) that is orthogonal to the axis of said shaft

(10).

3. Apparatus as claimed in claim 1 or 2, characterised in that said fastening means (12) of the reducer (4) achieve a cylindrical coupling between the reducer and the body (11), coaxial with the crankshaft (10).

4. Apparatus as claimed in any of the previous claims, wherein said transmission means comprise a system of belts (5) and related pulleys for the transmission of motion.

5. Apparatus as claimed in claim 4, characterised in that it comprises means for moving the motor (3) relative to the fixed body (7), to tension said system of belts (5).

6. Apparatus as claimed in claim 5, wherein said means for moving the motor comprise at least one slide (8) whereto is fastened the motor (3) and at least one actuating means (9), operatively active on the motor in a direction away from / towards the reducer (4).

7. Apparatus as claimed in any of the previous claims, wherein said means for fastening the reducer to the pump body comprise a flange (12), means for connecting said flange to the reducer (4) and means for connecting the flange (12) to the fixed body (7).

8. Apparatus as claimed in claim 7, wherein said means for connecting the flange (12) to the reducer comprise a plurality of screws (13a).

9. Apparatus as claimed in claim 7 or 8, wherein said means for connecting the flange (12) to the fixed body (7) comprise a plurality of screws (13b).

10. Apparatus as claimed in claim 7, wherein the flange (12) is provided with a planar coupling surface that is orthogonal to the axis of symmetry of the flange and coincides with that of the crankshaft (10).

11. Apparatus as claimed in claim 7, wherein the flange (12) is provided with a cylindrical coupling surface that is coaxial with the corresponding cylindrical surface of the fixed body (7), said surfaces being in turn coaxial with the axis of the crankshaft (10).

12. Transmission apparatus (1), in homogeniser or high pressure piston pump, said apparatus comprising:

- a fixed body (7) housing a rotating crankshaft (10);

- a motor (3) able to actuate said crankshaft (10) through transmission means (5, 6); - a reducer (4) interconnected between said shaft (10) and said transmission means; characterised in that it comprises means for rigidly fixing the reducer (4) to said fixed body (7), preventing oscillations of the reducer relative to the crankshaft.

13. Method for assembling a transmission apparatus, in homogeniser or high pressure piston pump, said apparatus comprising a fixed body (7) housing a rotating crankshaft (10), characterised in that it comprises the following steps: - fastening a reducer (4), keyed on the crankshaft (10), rigidly to said fixed body (7), in order to inhibit all oscillations of the reducer relative to the crankshaft;

- connecting the reducer (4) to a motor (3) by means of a system of transmission belts (5) and associated pulleys; - tensioning the transmission belts (5) by translating the motor (3), said motor being movable relative to said fixed body (7);

- locking the motor relative to the fixed body, once tensioning is complete.

14. Method as claimed in claim 13, characterised in that said step of fastening the reducer (4) keyed on the crankshaft (10) to the fixed body (7) comprises a step of fastening a flange (12) to the fixed body and a step of fastening the reducer to the flange, said flange achieving a substantially cylindrical coupling.

15. Homogeniser or high pressure piston pump, characterised in that it comprises a transmission apparatus (1) of the type claimed in any of the claims 1 through 12.