GB2462365A

GB2462365A - Hand-held power tool with blowing duct

Info

Publication number: GB2462365A
Application number: GB0913528A
Authority: GB
Inventors: Marcel Casota; Jingying Zhao
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2008-08-07
Filing date: 2009-08-03
Publication date: 2010-02-10
Also published as: GB0913528D0; CN101642833A; DE102008041094A1

Abstract

A hand-held power tool, such as a jigsaw (12a, fig 1), comprises a housing (14a, fig 1), at least one directing device 16a for directing at least one blower flow (18a, fig 3), where the directing device has at least one deflecting duct 20a. Preferably, the deflecting duct includes at least two sections that extend in different directions. The directing device may have at least one mounting body 72a, which forms at least one part of the deflecting duct. Preferably, the direction duct extends at least partly outside the housing.

Description

Hand-held power tool

Prior art

The invention starts from a hand-held power tool, in particular a jigsaw according to the precharacterising clause of Claim 1.

Hand-held power tools having a housing and a directing device for directing a blower flow have already been proposed.

Advantages of the invention The invention starts from a hand-held power tool, in particular a jigsaw, having a housing and at least one directing device for directing at least one blower flow.

It is proposed that the directing device has at least one deflecting duct. In this context, a "directing device" is to be understood as meaning in particular a device, such as, for example, a duct, which prescribes and/or determines a direction and/or a path of a blower flow, such as an air flow produced by a blower and/or fan, and/or directs the blower flow. This path runs advantageously from the blower arranged in the housing to a place of action, such as, for example, a tool, such as a saw blade and/or during operation of the hand-held power tool a cutting location of the saw blade and/or a machining location of a workpiece. A "deflecting duct" is to be understood here as meaning in particular a duct which has at least one deflection and/or by means of which a specific change of direction of the blower flow can be achieved and which, before and after the at least one deflection and/or the change of direction, specifically guides and/or directs the blower flow, preferably in the form of a single concrete component part, and in particular delimits the blower flow from at least two sides in at least one region transversely with respect to its flow direction. A deflection in this case defines in particular a change of direction on the path of the blower flow, which change of direction is specifically guided, and/or is preferably prescribed by a single component part.

Furthermore, the deflecting duct preferably forms an air duct. The deflecting duct preferably extends from the blower up to an outlet device and/or outlet opening which is arranged within a radius of approximately 5 cm from the tool and/or during operation of the hand-held power tool in the immediate vicinity or approximately within a radius of 3 cm from the cutting location of the saw blade and/or the machining location of a workpiece. In principle, however, a more remote arrangement would also be conceivable.

Advantageously, the deflecting duct has a constant cross-section over its entire extent. However, it would also be conceivable for the cross-section to be designed differently from a cross-section of another region of the deflecting duct, for example narrower in the region of the outlet device and/or outlet opening and/or wider in a mounting region than another section of the deflecting duct, such as, for instance, a section which substantially defines a main extent of the deflecting duct. By virtue of the configuration according to the invention, it is possible to achieve an advantageous and specific guidance of the blower flow which is guided directly to the place of action of the saw blade, the cutting location, in order to effectively remove or blow away machining residues and/or dust resulting there. In addition, it is possible to design an outflow from the housing to be guided in a defined manner.

It is further proposed that the deflecting duct has at least two deflections, with the result that a further guided change of direction and in particular a change of direction back to an original orientation of the deflecting duct or of the blower flow can be achieved in a constructionally simple manner.

Advantageously, the deflecting duct comprises at least one duct wall, which separates a flow cross-section of the deflecting duct from further components situated inside the housing. A "duct wall" is to be understood here as meaning in particular a construction, such as, for example, a separate housing, which surrounds the blower flow over a large part, of 30%, preferably of 50% and particularly preferably of 75%, of its extent, namely from the blower up to the outlet opening, preferably on four sides as a component part, and/or seals and/or screens and/or separates the blower flow, guided in the deflecting duct, from an environment of the deflecting duct and/or from components, so that a spreading of the air of the blower flow into a region outside the duct wall is prevented. In principle, it would also be conceivable for the duct wall to surround the blower flow over its entire extent, in particular as a component part. In this case, components and in particular "components situated inside the housing" are in particular component parts, such as, for example, a motor, a fan, a motor cooling means, gearing parts, electronic and control component parts, webs and/or other component parts which appear appropriate to a person skilled in the art and which are arranged inside a housing and/or a gearing compartment and/or motor compartment of the hand-held power tool, and/or gases, such as, for instance, air, which are situated in the housing and/or between the component parts. A "flow cross-section" is to be understood here as meaning in particular a cross-section through the duct wall, via which cross-section, when seen in the flow direction of the blower flow, a flow takes place. In addition, the duct wall is provided for separating the blower flow, also outside the housing, from an ambient air situated in the region around the hand-held power tool, and/or from machining residues and/or other substances which appear to a person skilled in the art to be a nuisance. By virtue of the realisation of the duct wall, the blower flow can be guided in a constructionally simple manner directly or in a manner free from interference and turbulence from its place of origin, such as the blower, to its place of action, such as the saw blade.

Furthermore, it is advantageous when the deflecting duct extends at least partly outside the housing, "at least partly outside the housing" here meaning in particular that the deflecting duct extends outwards away relative to a surface of a housing component part which is arranged opposite a surface of the housing component part facing the gearing compartment. As a result, turbulence which would arise when an unguided blower flow leaves the housing is avoided in a particularly simple manner.

In a further configuration of the invention, it is proposed that at least 20% of the deflecting duct lies outside the housing. Advantageously, at least 50% of the deflecting duct lies outside the housing, although in principle a different percentage, such as, for example, 100%, would also be conceivable here. By virtue of this configuration, an advantageous bridging of a space between a lower side of the hand-held power tool facing the workpiece and the workpiece can be realised. Furthermore, a particularly exact guidance of the deflecting duct up to the machining location of the workpiece is thereby obtained.

Furthermore, it is proposed that the deflecting duct has at least two sections which extend in different directions. A "section" is to be understood here as meaning in particular a sub-region of the deflecting duct. The phrase "different directions" means here in particular any angular difference, such as, for example, 135° and/or 90°, between orientations of the two sections of the deflecting duct. It is also possible to provide more than two sections, of which in turn at least two may have the same orientation or direction. By virtue of this different orientation of the sections and thereby of the deflecting duct, it can be made possible in a constructionally simple manner to specifically adapt the deflecting duct to structural conditions of the hand-held power tool.

It may further be advantageous when there is provided a drive unit which imparts a reciprocating movement in a reciprocating direction, to which at least one section of the deflecting duct extends substantially parallel. A "drive unit which imparts a reciprocating movement in a reciprocating direction" is to be understood here as meaning in particular a unit, such as a motor, which in at least one operating state of the hand-held power tool, drives a further component part, such as a reciprocating element, in an upward and downward movement, in particular a continuous or periodic upward and downward movement. In this context, "substantially parallel" is to be understood as meaning in particular that the section of the deflecting duct is oriented with an angular deviation of less than plus/minus 15°, preferably less than plus/minus 5° and particularly preferably less than plus/minus 2°, in relation to the reference object, here the reciprocating direction. The parallel section is preferably the sub-region of the deflecting duct which is arranged substantially along the direction of the main extent of the deflecting duct. By virtue of the fact that the section of the deflecting duct extends substantially parallel to the reciprocating direction, a preferably compact construction of the directing device or of a machining residue removal means can be made available.

An effective blower flow supply to the cutting location can advantageously be achieved when a bearing element is made available, to the main extent of which at least one section of the deflecting duct extends substantially parallel. In this context, a "bearing element" is to be understood as meaning in particular a means, such as, for example, a slide shoe, which bears the hand-held power tool and/or is provided for a guidance of the hand-held power tool.

In addition, it is proposed that the deflecting duct is provided for directing the blower flow substantially parallel to a bearing element after leaving the deflecting duct. In this case, "directing the blower flow" is to be understood as meaning in particular that the blower flow leaves the outlet device of the deflecting duct in a directed manner and a flow direction of the blower flow is substantially retained at least between the outlet device and the cutting location, "substantially retained" here meaning that deviations of up to plus/minus 15° with respect to the flow direction are permissible. Furthermore, "provided" is to be understood as meaning specially equipped and/or designed. The blower flow preferably flows in a plane extending substantially parallel to a plane of the main-extent surface of the bearing element, it being possible for the planes to be arranged at the same level when seen in a reciprocating direction. By virtue of the realisation of the directed blower flow, firstly a good and effective blowing action on the cutting location can be achieved and secondly a good view, in particular unhindered by machining residues, of the cutting location can be achieved.

Advantageously, for this configuration the outlet device is arranged directly at the cutting location, "directly" here defining an immediate spatial proximity of a radius of approximately 10 cm, preferably 5 cm and particularly preferably less than 3 cm, around a location of interaction of the saw blade with the workpiece or a machining plane.

The blower flow can thus act directly at the cutting location.

A preferred development consists in providing a supporting device of a tool, under the end of the extent of which device, when seen in the reciprocating direction, at a side facing away from the housing, at least the deflecting duct opens substantially. In this context, a "supporting device" is to be understood as meaning a device, such as, for example, a roller lever and/or a guide cheek, against which the tool, at least in an operating state, is supported on at least one side and/or which has a bearing surface for the tool. Furthermore, "under the end of the extent of which device, when seen in the reciprocating direction" is to be understood as meaning a spatial arrangement in which the blower flow after leaving the outlet device is blown out substantially, i.e. by at least 80%, preferably 90% and particularly preferably 100%, under the end of the supporting device facing away from the housing.

Disadvantageous turbulence due to impingement of the blower flow on the supporting device can be avoided in a constructionally simple and efficient manner by virtue of the configuration according to the invention.

In addition, it is proposed that the deflecting duct is arranged, when seen in a main machining direction of the hand-held power tool, before the supporting device of the tool. In this context, a "main machining direction" is to be understood as meaning in particular a direction which is defined by a sawing direction or by a working surface of the tool or of the saw blade. By virtue of this arrangement of the deflecting duct, a construction is achieved in which both a cutting process of the saw blade and a removal of machining residues by the blower flow can be designed in a constructionally simple and efficient manner.

It is further proposed that the directing device has at least one mounting body, which forms at least one part of the deflecting duct. In this case, a "mounting body" is to be understood as meaning in particular a body which has at least one mounting element, such as, for example, at least one recess and/or in particular at least one bar, by means of which the directing device can be arranged on the housing and/or connected to the housing. The mounting body may also be designed in one piece with the housing. The mounting body may correspond substantially to a configuration of the directing device known to a person skilled in the art. By virtue of the presence of the mounting body, the function of the directing of the blower flow and a mounting of the directing device can be combined to save component parts. Furthermore, a mounting location of a known directing device can be used in a constructionally simple manner for a mounting of the deflecting duct.

Advantageously, at least one deflection is arranged, in the flow direction of the blower flow, after the mounting body.

Preferably, this deflection can be arranged and/or integrated in a section of the deflecting duct which constitutes an extension of the mounting part, which extension is arranged substantially along the direction of the main extent of the deflecting duct, with the result that the change of direction of the blower flow can be directed particularly expediently into the path from the blower or the mounting location to the blowing-out opening.

Furthermore, it is advantageous when the mounting body extends substantially parallel to the bearing element, with the result that a compact bearing of the directing device can be made available.

A preferred development consists in that the deflecting duct is asymmetrically designed. In this context, "asymmetrically" is to be understood as meaning in particular a configuration in which, for example, an exit cross-section of the outlet device is designed asymmetrically and/or inhomogeneouSly. By virtue of the asymmetric configuration, the directing device can be adapted in a constructionally simple and output-increasing manner to conditions of the hand-held power tool, such as, for instance, a motor direction of rotation and concomitant phenomena, such as a blower flow thereby specifically increased on a side of the directing device which is arranged in a direction counter to the direction of rotation of the motor.

In a further configuration of the invention, it is provided that the directing device is formed in one piece with at least one housing component part. In this context, "in one piece" means in particular that the directing device can be separated from the housing component part only with a functional loss of the directing function of the blower flow. The directing device can in this case be connected to the housing component part by all kinds of materially united connections which appear appropriate to a person skilled in the art, such as, for example, an adhesive bonding, a welding, a sintering, a soldering and/or by an injection moulding. By virtue of this configuration, a particularly component part-saving construction of the directing device and thus of the hand-held power tool can be achieved.

Drawing Further advantages emerge from the following description of the drawing. Exemplary embodiments of the invention are illustrated in the drawing. The drawing, description and claims contain numerous features in combination. A person skilled in the art will also consider the features, expediently, individually and combine them to form appropriate further combinations.

In the drawing: Fig. 1 shows a schematic illustration of a jigsaw having a directing device according to the invention, Fig. 2 shows the directing device from Figure 1 in a perspective illustration, Fig. 3 shows the directing device from Figure 1 in a sectional illustration, Fig. 4 shows a section along the line IV-IV through the directing device of Figure 3, Fig. 5 shows a detail view of a working region of the jigsaw from Figure 1 having a directing device according to the invention in a mounted state, Fig. 6 shows a further view of the working region having the directing device of Figure 2, Fig. 7 shows an illustration of an alternative directing device, and Fig. 8 shows an alternative jigsaw having a directing device integrated in a housing component part.

Description of the exemplary embodiments

Figure 1 shows a hand-held power tool lOa in the form of a jigsaw 12a, having a housing 14a, in which a motor 76a is arranged, and at least one directing device 16a for directing a blower flow 18a or an air flow (see Fig. 5) The directing device 16a has a deflecting duct 20a, which is arranged, in the flow direction, in a flow path 78a of the blower flow l8a (see Figure 5) between a blower 82a arranged in the motor compartment BOa and a machining location 84a or a cutting location or an interacting location of a tool 64a in the form of a saw blade 86a for a workpiece 88a, which defines a machining plane. In addition, the jigsaw 12a has a drive unit 54a, such as a pendulum gearing 92a, which is arranged in a gearing compartment 90a and which imparts a reciprocating movement in a reciprocating direction 56a and thereby drives a reciprocating element 94a, such as a reciprocating rod, which carries the saw blade 86a, in a continuous upward and downward movement in an operating state or a working mode.

Furthermore, the jigsaw has a bearing element 58a in the form of a slide shoe 96a and a supporting device 62a for the tool 64a in the form of a roller lever 98a.

The directing device 16a is shown in detailed illustrations in Figures 2 and 3. The directing device 16a has a mounting body 72a, which forms a part or a first section 36a and a second section 38b of the deflecting duct 20a (see Fig. 3) The sections 36a, 38a are connected via a deflection 22a and extend in different directions 46a, 48a, the direction 48a deviating downwards by an angle a of approximately 35° from the direction 46a of the section 36a and a main extent lOOa of the mounting body 72a, when seen in the direction of the flow path 78a. The section 38a is followed via a further deflection 24a, in the direction of the flow path 78a of the blower flow 18a, by a section 40a which has a direction 50a which deviates by an angle 13 of approximately 5° from the direction 48a of the section 38a. A further section 42a extends, following the section 40a, in a direction 52a with a deviation of a further deflection 26a by an angle y of approximately 500 with respect to the direction 50a of the section 40a. In addition, the section 42a is arranged perpendicularly with respect to the section 36a. Furthermore, the section 42a merges by means of a fourth deflection 28a into a further section 14a which is arranged at an angle 5 of approximately 90° with respect to the section 42a. In addition, the section 44a extends in the same direction 46a as the section 36a and is thus oriented parallel with respect to the latter. The sections 36a, 38a, 40a, 42a and 44a are thus arranged one after the other in the flow path 78a of the blower flow 18a and in each case undergo a change of direction by a respective deflection 22a, 24a, 26a, 28a. In addition, the deflections 24a, 26a, 28a are arranged, in the flow direction or in the flow path 78a, after the mounting body 72a. The section 42a constitutes the greatest rectilinear portion of the flow path 78a or of the deflecting duct 20a, or an orientation or the direction 52a of the section 42a determines a main course of the deflecting channel 20a, so that the main extent 102a of the directing device 16a or of the deflecting duct 20a is substantially prescribed thereby.

The deflecting duct 20a comprises a duct wall 30a, which separates a flow cross-section 32a of the deflecting duct 20a from further components 34a situated inside the housing 14a, such as, for example, the motor 76a, gearing parts 104a of a motor compartment 80a or of a gearing compartment 90a or air situated between these parts 14a, 76a, 104a, not illustrated in more detail here. The duct wall 30a forms, with respect to the housing 14a, a separate housing and is thus designed separately from the housing 14a of the hand--held power tool lOa. The duct wall 30a is formed by walls 106a, 108a, llOa, 112a which delimit the deflecting duct 20a on four sides. In relation to the flow path 78a of the blower flow 18a, the wall 106a is arranged in an upper region 114a of the mounting body 72a, whereas the wall 108a is arranged in a lower region 116a and the walls 110a and 112a are arranged on lateral regions 118a. The walls 106a and 108a extend, over the entire flow path 78a of the blower flow iSa, parallel to one another. The walls llOa and 112a in turn each extend perpendicularly to the walls 106a and 108a, with the result that the directing device 16a or the deflecting duct 20a has a substantially rectangular flow cross-section 32a, the flow cross-section 32a, for the purpose of a homogeneous and turbulence-free guidance, being configured with slightly rounded corners 120a and forming an air duct 122a (see Fig. 4) . In principle, however, another shape, such as circular and/or oval, of the flow cross-section 32a would also be conceivable.

The wall 106a has, in the regio1 of the mounting body 72a or of the sections 36a, 38a and in a starting region 124a of the section 40a, a wall section 126a which, in a direction 128a which is arranged in each case perpendicularly to the directions 46a, 48a, 50a and intersects the wall section l26a, is designed thicker at an outer side 130a facing away from the air duct 122a than the wall 106a in the remaining regions, such as in an end region 132a of the section 40a, in the section 42a and 44a, and the wall lOSa. In addition, the wall section 126a widens, in the perpendicular direction 128a, in the starting region 124a of the section 40a to form a projection 134a. In general, the mounting body 72a may also be differently designed, in particular in a form which is adapted to a mounting location of the directing device 16a.

The walls llOa and 112a have, at the lateral regions 118a in the region of the mounting body 72a or of the sections 36a, 38a and in the starting region 124a of the section 40a, wall sections 136a, 138a which, in a direction l28a which in each case is arranged perpendicularly to the directions 46a, 48a, 50a and intersects the walls sections 136a and 138a, are designed thicker at an outer side 130a facing away from the air duct 122a than the walls llOa and 112a in the remaining regions, such as in the end region 132a of the section 40a and in the sections 42a, 44a. In the region of the section 36a of the wall sections 136a, 138a, there are arranged in each case two mounting elements l4Oa in the form of bars 142a extending parallel to the direction 46a, only the two bars l42a of the wall 106a being shown in Figure 2. In addition, the projection l34a has a mounting element l4Oa in the form of an indentation 144a. By means of the mounting elements 140a, the mounting body 72a is mounted in appropriately corresponding mounting means (not shown specifically) in a housing component part 146 (see Figure 5) of the hand-held power tool lOa.

The mounting body 72a has, from an outer side 130a of the wall section 136a to an outer side 130a of the wall section 138a, an extent 148a of approximately 2 cm (see Figure 2) An extent 150a of the mounting body 72a from an upper side 152a of the wall 106a in the section 36a to a lower side 154a of the wall 108a in this section 36a is approximately 1 cm (see Figure 3) . A length 156a of the mounting body 72a along the flow path 78a of the blower flow iSa is approximately 1.5 cm (see Figure 2). The end region 132a of the section 40a, and the sections 42a and 44a, form an extension 158a of the mounting body 72a, which extension has an extent 160a from an outer side 130a of the wall lO6a to an outer side 130a of the wall 108a of approximately 0.5 cm and an extent 162a from an outer side 130a of the wall llOa to an outer side 130a of the wall 112a of 1 cm (see Figure 4) For a reduction of the extent 148a of approximately 2 cm of the duct wall 30a in the sections 36a, 38a and the starting region 124a of the section 40a to the extent 162a of approximately 1 cm or the flow cross-section 32a of the end region l32a of the section 40a and of the sections 42a, 44a, sloping surfaces l64a running in the direction of the air duct 122a are provided, at the level of the section 38a and the starting region 124a of the section 40a, on the wall sections l36a, 138a (see Figure 2) Over the entire flow path 78a of the air duct 122a, the walls lO6a and 108a are at a distance 166a of approximately 0.25 cm and the walls llOa and 112a are at a distance l68a of approximately 0.75 cm (see Figure 4) . However, in principle, other dimensions would also be conceivable for the mounting body 72a, the extension 158a and the air duct 122a.

Figure 5 shows a detail view of the jigsaw l2a or of the machining location 84a of the jigsaw 12a having a mounted directing device 16a in a sectional illustration. In the mounted state or when the directing device l6a is installed, by the mounting body 72a and the mounting elements 140a arranged thereon, in a mounting region 170a of the housing component part 146a, the deflecting duct 20a extends outwards away and in the direction of the bearing element 58a relative to a surface 172a of the housing component part 146a which is arranged opposite a surface l74a of the housing component part 146a facing the gearing compartment 90a, with the result that the deflecting duct 20a extends partly outside the housing 14a and thus about 50% of the deflecting duct 20a or substantially the sections 42a and 44a lie outside the housing 14a and bridges a space between a lower side 206a of the hand-held power tool lOa facing the workpiece 88a and the workpiece 88a. By virtue of the duct wall 30a, the air duct 122a or the blower flow l8a is also separated outside the housing l4a from an ambient air l76a situated in the region around the hand-held power tool lOa and from machining residues (not illustrated specifically here) resulting during a working process and can thus reach the machining location 84a unhindered.

When seen in a main machining direction 70a of the hand-held power tool l0a, the deflecting duct 20a is arranged before the supporting device 62a of the tool 64a. In this case, the main machining direction 70a is defined by a sawing direction or by an orientation of a working surface 178a of the tool 64a or of the saw blade 86a.

The section 42a of the deflecting duct 20a extends substantially parallel to the reciprocating direction 56a of the reciprocating movement imparted by the drive unit 54a, and the mounting body 72a or the section 36a and the section 44a of the deflecting duct 20a extend substantially parallel to a main extent 60a of the bearing element 58a.

In this case, the section 44a ends in an outlet device or in an outlet dpening lBOa and directly at or within a radius of 2 cm around the machining location 84a or cutting location of the saw blade 86a.

As can be seen in Figure 6, the deflecting duct 20a, when seen in a reciprocating direction 56a, opens substantially under an end of the extent 66a at a side 68a, facing away from the housing 14a, of the supporting device 62a of the tool 64a, and to be precise at a distance of about 2 mm above a main-extent surface 182a of the bearing element 58a (only indicated schematically here) . By virtue of this arrangement, the deflecting duct 20a is provided for directing the blower flow 18a substantially parallel to the bearing element 58a after leaving the deflecting duct 20a (see also Figure 5) . The blower flow 18a thus flows in a plane 184a extending substantially parallel to a plane of the main-extent surface 182a of the bearing element 58a.

Alternative exemplary embodiments of the hand-held power tool lOa and of the directing device 16a are illustrated in Figures 7 and 8. Component parts, features and functions which remain essentially the same are denoted fundamentally by the same reference symbols. To distinguish the exemplary embodiments, however, the letters b or c are added to the reference symbols of the exemplary embodiments. The following description is restricted essentially to the differences from the exemplary embodiment in Figures 1 to 6, while reference may be made to the description of the exemplary embodiment in Figures 1 to 6 with regard to component parts, features and functions which remain the 3D same.

Figure 7 shows a front view of an alternative directing device 16b which serves for directing a blower flow 18b and has a deflecting duct 20b. An axis 186b, which is oriented parallel to the wall 106b and the wall sections 136b and 138b of the directing device 16b, divides a mounting body 72b into two halves 188b and l9Ob of the same size. An outlet opening 180b or an exit cross-section 192b of the outlet opening 180b is, in contrast, divided by the axis 186b asymmetrically into two halves l94b and 196b with the lengths 198b and 200b, with the result that the deflecting duct 2Gb is asymmetrically designed. In this case, the half which is arranged on a side of the directing device l6b which is arranged in a direction counter to the direction of rotation 202b of the motor (not shown here) is designed longer, with the result that more air is blown out of the deflecting duct 20b via the half l94b, although less blower flow l8b is produced at a blower (not shown here) on this side of the deflecting duct 20b owing to the direction of rotation 202b of the motor.

Figure 8 shows an alternative hand-held power tool bc in the form of a jigsaw 12c having a housing 14c and a directing device l6c for directing a blower flow 18c, the directing device l6c having a deflecting duct 20c and being formed in one piece with a housing component part 74c, the housing component part 74c forming a mounting body 72c and being formed by a housing shell 204c. The directing device l6c or the deflecting duct 20c has five sections 36c, 38c, 40c, 42c and 44c which are arranged one after the other in a flow path 78c of the blower flow l8c and in each case undergo a change of direction by a respective deflection 22c, 24c, 26c, 28c. The sections 36c and 38c are directly integrated in the housing component part 74c and the sections 40c, 42c and 44c form an extension 158c extending outside the housing l4c and are injection-moulded onto the housing component part 74c. The deflections 24c, 26c and 28c are thus arranged, in the flow direction or in the flow path 78c of the blower flow 18c, after the mounting body 72c.