GB2236964A

GB2236964A - Separator

Info

Publication number: GB2236964A
Application number: GB9021503A
Authority: GB
Inventors: Michael Krueger; Juergen Maab
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1989-10-19
Filing date: 1990-10-03
Publication date: 1991-04-24
Also published as: JPH0360866U; DE8915734U1; GB9021503D0; FR2654272B3; SE9003325L; FR2654272A3; SE9003325D0

Abstract

A separator 1, designed to remove dust and ink droplets from cooling air which is directed by a blower 3 on to an electric motor 2 driving a printing machine, comprises a housing through which air flows from inlet 10 to outlet 12 round baffles 14, 16, 17 which impose two reversals of direction on the air stream. Baffle 16 also defines the top of a dead space 5a. To clean the separator one side wall 20 can be removable, or the floor 18 may slide out like a drawer. In Fig. 2 baffle 14 is replaced by curved surfaces (21 22). <IMAGE>

Description

DESCRIPTION ELECTRIC MOTOR COOLING DEVICE The invention relates to a filter arrangement for a cooling device of an electric motor, in particular of a drive motor on a rotary printing machine, with a blower to supply the electric motor with cooling air and a filter positioned downstream of the blower.

It is known for the suction inlet opening of a blower supplying an electric motor with cooling air to be provided sometimes merely with a lattice to protect against contact. and sometimes with a filter mat to clean the cooling air. In the case of exclusive protection by means of a lattice, there is then an increased danger of damage to the electric motor, in particular when it is run at a high operating temperature and is used for a drive on a rotary printing machine. This is because in the immediate vicinity of a rotary printing machine, an atmosphere is present which features a certain proportion of ink vapour containing solvent.The direct consequences of this are that the meshes of the lattice clog, the blade profile of the blower is evened out, the cooling channels provided in the electric motor clog, and damage to the carbon brushes can ensue, by deposits on (for example) the commutator of a direct current motor. In particular, those phenomena mentioned which occur directly on the electric motor are favoured even more by a high operating temperature, since in this case, the solvent evaporates especially quickly from a liquid film formed by the ink vapour, leading to the formation of a crust and finally to the blockage of cooling channels. An indirect consequence of this is a resultant overheating of the electric motor due to a lack of adequate supply of cooling air.

By oceans of the aforementioned use of filter mats, the danger of blockage of cooling channels in the electric motor and the damage to carbon brushes is indeed countered, but this must be achieved at the cost of frequent exchanging of the filter mats, which by virtue of their nature become blocked more quickly than lattice meshes or even cooling channels in the electric motor. Hence, in the case of the use of filter mats in particular, it is not adequate merely to monitor the motor temperature to ensure reliable operation. Rather, it is necessary to undertake a costly differential measurement in order to monitor an adequate flow of cooling air if the electric motor is constantly run at its upper temperature limit, since an exact temperature measurement on the electric motor is difficult.

In order to cool electrical switch boxes, electronic housings or similar equipment which must be ventilated during operation and kept free of dust and foreign bodies, it is known for a blower supplying such a piece of equipment with cooling air to have a labyrinth filter positioned downstream of it, divided basically into two parts and consisting of a lower and an upper part, separable from one another and provided with interlocking, comb-like lamellas (DE-PS 34 23 047).

In this case, the intention is to take account of a given degree of impurity of the cooling air flowing through the filter, by means of the appropriate choice of distance, number and steepness of the individual lamellas positioned opposite one another.

Thus in the case of heavy impurity, a minimum of a relatively large number of lamellas would be aimed for. The reference to influence on the result of cleaning by an appropriate choice of steepness for the lamellas results in the fact that, in the case of a high degree of impurity, as large an inclination of the lamellas as possible in relation to a housing base and housing cover of the labyrinth filter is aimed for, and additionally of such a nature that the free lamella ends point in the direction of the inlet opening. However, both measures considerably increase the pressure head in the labyrinth filter, so that in order to achieve a high throughput of cooling air, a relatively high suction performance is required from the blower.The same also applies to the case where a relatively smaller reciprocal distance of the lamellas is provided in adaptation to the degree of impurity of the cooling air.

It is the task of the invention to guarantee lowmaintenance and also reliable operation of an electric motor with the smallest possible expenditure of energy.

This task is accomplished by means of a filter arrangement according to Claim 1.

With the filter arrangement according to the invention, a certain separation is achieved of fine dust and paper dust, which is not harmful to the electric motor, from cooling air which is contaminated with such dusts and ink vapour. An essential advantage consists in the fact that ink vapour retained in the filter arrangement from cooling air of this sort cannot act harmfully on the electric motor.

The ink vapour is retained in the filter arrangement by virtue of its being precipitated in particular on chamber walls which form deflecting surfaces, and on such areas of chamber walls as are located close to an outer orbit of a curved area of the air stream. A precipitation occurs in this case on a chamber wall forming a deflection surface as a result of its retention effect, and on a surface of a chamber wall located close to an outer orbit of a curved area of the air stream as a result of centrifugal forces which act on ink droplets of the ink vapour contained in the cooling air.

This already results in a separation of, on the one hand, ink vapour retained in the filter arrangement and, on the other hand, fine dust and paper dust which partially passes the electric motor more or less unimpeded in the further course of events.

However, the filter arrangement according to the invention does not only retain ink vapour but also dusts. Here, it proves to be of further advantage for the retained ink vapour, on the one hand, and the retained dusts, on the other, to be deposited in essentially separate physical locations from one another. This is because while a precipitation of the ink vapour in the aforementioned manner is taking place on specific areas of chamber walls, a considerable part of the dusts carried along by the cooling air is being gathered in the area of the intermediate chamber, forming a dead space, in which a flow-abated zone is created. A further part of the dusts is bound into the precipitated ink vapour.

Thus the dust load on the electric motor is also considerably reduced by means of the proposed design of the filter housing.

Furthermore, a filter arrangement according to the invention has the advantage that even in the case of very well utilised electric motors, that is, those with a relatively high operating temperature, a simple motor temperature monitoring device is adequate to monitor the motor cooling. This process would be harmful for an electric motor run in this way if the intervals until the attainment of the permissible maximum temperature were relatively short, for example as a result of the blockage of filter mats.

The filter arrangement according to the invention serves simultaneously as a protection against contact, so that it is possible to dispense with a protective lattice for the suction opening of the blower.

Furthermore. the flow cross-sections of the filter arrangement according to the invention can without particular expenditure be designed so large that a high throughput of cooling air and a relatively small pressure head are achieved in the filter arrangement.

A development of the filter arrangement according to the invention is distinguished by a reciprocal positioning of the second overflow opening and the outlet opening, of such a nature that change of direction corresponding essentially to a reversal of direction, and a subsequent further deflection of the air stream, take place in the air outlet chamber.

This development represents an optimisation of the filter arrangement, inasmuch as the centrifugal forces which occur during the reversal of direction of the air stream in the air outlet chamber precipitate ink droplets which are still contained in the air stream after passing the intermediate chamber, and inasmuch as a similar effect again occurs with the subsequent deflection of the air stream.

A further development is distinguished by a positioning of the air inlet chamber, intermediate chamber and air outlet chamber such that the air stream is guided between parallel lateral walls of the filter housing, the changes of direction occur in vertical planes, and the air inlet chamber is positioned above the intermediate chamber.

In this case, in particular, the precipitation of ink droplets in the intermediate chamber is additionally favoured by the force of gravity, and the formation of air inlet chamber, intermediate chamber and air outlet chamber may be effected in a particularly simple manner, as further detailed below.

In order to increase the aforementioned centrifugal forces and thus further to improve the result of the precipitation of ink droplets, another development provides for the first overflow opening to feature a smaller cross-section than the inlet opening.

A particularly simple construction of a filter arrangement according to the invention can further be achieved by the provision of flat chamber walls.

The precipitation of ink droplets on the chamber walls is, however, favoured by a constructional version of the filter arrangement according to the invention, distinguished by the fact that curved chamber walls are provided, favouring the changes in direction of the air stream, for the formation of the air inlet chamber and the air outlet chamber.

Since, in the case of low-maintenance operation of an electric motor achieved with the invention, it proves favourable even when there are very long intervals between each maintenance if maintenance work falling due can be performed without major expense, a further development provides for a lateral wall of the filter housing to be detachably connected to the filter housing.

In connection with the aforementioned positioning of air inlet chamber, intermediate chamber and air outlet chamber which brings about guiding of the air stream between parallel lateral walls of the filter housing, the detachable connection of a lateral wall results in access to the entire inner area of the filter housing, from which ink and dust deposits can then be removed; this is extremely favourable for maintenance purposes.

A further improvement in ease of maintenance is achieved by means of a constructional version which is distinguished by the fact that a lower area of a lateral wall of the filter housing is designed as a panel of a drawer which can be pulled out of the filter housing.

In connection with a lateral wall which is detachable from the filter housing, this results in the possibility of easy removal of accumulated dust and of any abrased ink deposits, which can be collected in the drawer.

The invention is explained below in more detail with reference to the constructional versions represented in the drawings, wherein: Figure 1 shows a simplified general view of an electric motor equipped with a blower, and a filter arrangement according to the invention fitted downstream of such blower, with a sectional representation of the filter housing; Figure 2 shows a simplified representation of a filter arrangement according to the invention with design for the chamber walls divergent from Figure 1; and Figure 3 shows a partial section through a filter arrangement according to the invention, following the sectional sequence given in Figure 1.

In the case of the constructional version represented in Figure 1, a filter housing 1 immediately adjoins a blower 3 set above an electric motor 2. The filter housing is subdivided into an air inlet chamber 4, an intermediate chamber 5 and an air outlet chamber 6.

In this case, the air inlet chamber 4 is connected with the intermediate chamber 5 via a first overflow opening 7, and the air outlet chamber 6 is connected with the intermediate chamber 5 via a second overflow opening 8. An inlet opening 10 is provided in a first housing wall, and an outlet opening 12 is provided in a second housing wall. Thus the first housing wall represents a first front wall 9, and the second housing wall represents a second front wall 11, opposite the first one, of the filter housing 1.

When operating, the blower 3 immediately adjoining the outlet opening 12 produces an air stream which flows into the air inlet chamber 4 through the inlet opening 10, and flows out of the air outlet chamber 6 through the outlet opening 12. On its path through the filter housing 1, this air stream experiences a change of direction respectively in the air inlet chamber 4, in the intermediate chamber 5 and in the air outlet chamber 6. The change of direction indicated by an arrow 13 in the air inlet chamber 4 is forced by the reciprocal position of the inlet opening 10 and the first overflow opening 7. In the present example, the cross-sections of the inlet opening 10 and the first overflow opening 7 lie essentially in perpendicular planes to one another.

A first chamber wall 14 to subdivide the filter housing 1 forms a rear delimitation of the air inlet chamber 4 and a deflection surface for the air stream inside the air inlet chamber 4. Additionally, the air inlet chamber 4 is delimited by a front section 15a, facing the inlet opening 10, of a third front wall 15, and by a second chamber wall 16 opposite the third front wall 15, in which second chamber wall the first overflow opening 7 is also provided.

At the same time, the second chamber wall 16 forms a delimitation of the intermediate chamber 5, adjacent to the air inlet chamber 4; this intermediate chamber is further delimited by a section 9a, adjoining the second chamber wall 16, of the first front wall 9 ofi.

the filter housing 1, by a third chamber wall 17 representing a rear delimitation of the intermediate chamber, and by a front section 18a, extending from the first front wall 9 to the third chamber wall i7, of a fourth front wall 18 of the filter housing 1. A rear area 5b of the intermediate chamber 5 features, in addition to the first overflow opening 7, the second overflow opening 8, whereby their two crosssections are essentially in one and the same plane, but at the least in essentially parallel planes.

Thus, in the rear area 5b of the intermediate chamber 5, a change of direction is basically forced of the air stream flowing in through the first overflow opening 7 and flowing out through the second overflow opening 8. As a result of the centrifugal forces acting on the ink droplets of an ink vapour contained in the air stream, these ink droplets are precipitated in particular in an area of the front section 18a of the fourth lateral wall 18, which is located opposite the first overflow opening 7 and the second overflow opening 8.As a result of the designed positioning of the second overflow opening 8 in the rear area 5b of the intermediate chamber 5, i.e. in the immediate vicinity of the third chamber wall 17 delimiting the intermediate chamber 5 to the rear, a precipitation of ink droplets also takes place on the third chamber wall 17 in particular.

The causes of this are in part the aforementioned centrifugal forces, and in part the effect of the third chamber wall 17 as a deflection surface.

Adjoining the rear area 5b of the intermediate chamber is a front area Sa of the intermediate chamber 5, which extends in the direction of the first housing wall representing the first front wall 9. A dead space is created by means of this front area 5a within the intermediate chamber 5, in which a vortex is basically formed, indicated by arrow 19.

Although this vortex 19 should be regarded as a flowabated zone in comparison with the air stream passing through the filter housing 1, the aforementioned centrifugal forces also bring about a certain precipitation of ink droplets here. However, a considerable proportion of the dust carried along in the air stream is also precipitated in this flow- abated zone.

The second overflow opening 8, positioned in relation to the intermediate chamber in the rear area Sb thereof, is located in a front area 6a in relation to the air outlet chamber 6. The first chamber wall 14 forms a front delimitation of this front area 6a.

Adjoining this front area 6a is a rear area 6b, which is extended in such a manner that the third chamber wall 17 represents a front delimitation of an extended part of the rear area 6b. Furthermore, the air outlet chamber 6 is delimited by a rear section 15b of the third front wall 15, a rear section 18b of the fourth front wall 18 and the second front wall 11. The cross-sections of the second overflow opening 8 and of the outlet opening 12 are, once again, in planes which are essentially perpendicular to one another. In addition, the outlet opening provided in the second front wall 11 is positioned behind the third chamber wall 17. Thus in the air outlet chamber 6, the air stream is forced to assume a change of direction corresponding essentially to a reversal of direction with a subsequent further deflection.

The first chamber wall 14, the second chamber wall 16 and the third chamber wall 17 extend respectively from a first lateral wall 20 to a parallel second lateral wall 20' of the filter housing 1, whereby the first lateral wall 20 and the second lateral wall 20' are positioned vertically. Within the scope of the invention, however1 a horizontal position is also feasible. The aforementioned assignation of chamber walls and lateral walls results in the extremely simple subdivision, already mentioned at further length above, of the filter housing 1 into the air inlet chamber 4, the intermediate chamber 5 and the air outlet chamber 6. Thus the air inlet chamber 4, as mentioned, is advantageously positioned above the intermediate chamber 5.The overflow openings 7 and 8 are also designed in an extremely simple manner, in that they are delimited respectively by the first lateral wall 20 and the opposite lateral wall 20', as well as, on the one hand, by a free edge of the second chamber wall 16 or the third chamber wall 17, and, on the other hand, by a free edge of the first chamber wall 14.

As opposed to a very simple design, represented in Figure 1, of a flat chamber wall 14, Figure 2 shows a constructional version in which the contours of upper delimitations of the air inlet chamber 4 and the air outlet chamber 6 are adapted to the changes in direction of the air stream. Here, instead of the first chamber wall 14 which can be seen from Figure 1, curved guiding surfaces 21 and 22 are provided according to Figure 2, which are provided (for example) by chamber walls 26, 27, in the form of guiding plates, appropriately curved and inserted between the lateral walls 20 and 20'.

For the purpose of the aforementioned simple cleansing of the filter housing, a lower area of the lateral wall 20' is designed, according to Figure 2, as a panel of a drawer 23 which can be pulled out of the filter housing 1.

In Figure 4, a detachable positioning of a lateral wall 20 is represented. For this purpose, the lateral wall 20 is provided at its lower end with right-angle brackets 24, which are inserted into the corresponding slot of a bevelled part of the fourth front wall 18, and a locking latch 25 is provided for the upper end of the lateral wall 20.

LIST OF REFERENCE SYMBOLS 1 Filter housing 2 Electric motor 3 Blower 4 Air inlet chamber 5 Intermediate chamber 5a Front area of the intermediate chamber 5 5b Rear area of the intermediate chamber 5 6 Air outlet chamber 7 First overflow opening 8 Second overflow opening 9 First front wall of the filter housing 1 9a Section of the first front wall 9 10 Inlet opening 11 Second front wall of the filter housing 1 12 Outlet opening 13 Arrow 14 First chamber wall 15 Third front wall of the filter housing 1 15a Front section of the third front wall 15 15b Rear section of the third front wall 15 16 Second chamber wall 17 Third chamber wall 18 Fourth front wall of the filter housing 1 18a Front section of the fourth front wall 18 18b Rear section of the fourth front wall 18 19 Vortex 20 Lateral wall 20' Lateral wall 21 Guiding surface 22 Guiding surface 23 Drawer 24 Bracket 25 Locking latch 26 Curved chamber wall 27 Curved chamber wall It will be understood that the invention has been described above purely by way of example, and that various modifications of detail can be made within the ambit of the invention.

Claims

1. An electric motor cooling device comprising a blower, which (in use) supplies the electric motor with cooling air, and an air filter, positioned on the intake side of the blower, wherein: the filter comprises a housing which is subdivided by means of chamber walls into an air inlet chamber, an intermediate chamber connected with the air inlet chamber via a first overflow opening, and an air outlet chamber connected with the intermediate chamber via a second overflow opening;; the filter is so designed, in respect of the positioning of the first overflow opening, of the second overflow opening, of an inlet opening in a first housing wall of the filter housing, of an outlet opening in a second housing wall of the filter housing, and of the chamber walls, that (in use) an air stream produced by the blower and flowing into the air inlet chamber through the inlet opening and flowing out of the outlet chamber through the outlet opening is subjected to respective changes of direction in the air inlet chamber, in the intermediate chamber, and in the air outlet chamber, the changes of direction being, at least in the intermediate chamber, changes of direction amounting substantially to a reversal of direction; and the intermediate chamber is so designed as to afford a region constituting a dead space which extends in the direction of the first housing wall and which adjoins a region of the intermediate chamber in which the first overflow opening and the second overflow opening are provided.

2. A device according to claim 1, wherein the second overflow opening and the outlet opening are so positioned with respect to one another that, in the air outlet chamber as well as in the intermediate chamber, a change of direction occurs (in use) which amounts substantially to a reversal of direction, this change of direction being followed by a further deflection of the air stream.

3. A device according to claim 1 or 2, wherein the air inlet chamber, intermediate chamber and air outlet chamber are so positioned that (in use) the air stream is guided between parallel lateral walls of the filter housing, the specified changes of direction of the air stream occurring in substantially vertical planes, and the air inlet chamber being positioned above the intermediate chamber.

4. A device according to claim 1, 2 or 3, wherein the first overflow opening has a smaller crosssection than the inlet opening.

5. A device according to any of claims 1 to 4, wherein the chamber walls provided are flat.

6. A device according to any of claims 1 to 4, wherein the air inlet chamber and the air outlet chamber are delimited by curved chamber walls which favour the specified changes in direction of the air stream.

7. A device according to claim 3, wherein the filter housing has at least one lateral wall which is connected detachably with the filter housing.

8. A device according to any of claims 1 to 7, wherein a lower portion of a lateral wall of the filter housing is designed as a panel of a drawer which can be pulled out of the filter housing.

9. An air filter, designed to be positioned on the intake side of an electric motor cooling blower, having features as recited in any of claims 1 to 8.

10. A device or filter according to claim 1 or 9, respectively, substantially as described with reference to any Figure or Figures of the accompanying drawings.

11. A rotary printing machine having a drive motor which is provided with a cooling device according to any of claims 1 to 8, or claim 10.