GB2412619A

GB2412619A - Drive unit for hand tool machine

Info

Publication number: GB2412619A
Application number: GB0505846A
Authority: GB
Inventors: Frank Fuchs
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2004-03-30
Filing date: 2005-03-21
Publication date: 2005-10-05
Anticipated expiration: 2025-03-21
Also published as: CN1676282A; DE102004016170A1; GB2412619B; GB0505846D0

Abstract

A hand tool machine, such as orbital sander 10, comprises a housing 12 which carries a drive unit operable by a suction air stream, such as that provided by a vacuum cleaner. The drive unit includes a radial turbine wheel 34 equipped with air blades (35, fig. 2). An inlet guide grille 44 forms at least one channel to direct the air radially inwards towards the outer circumference of the turbine wheel 34. A downstream part of the channel runs parallel to the axis of the turbine wheel 34, whilst an upstream part runs in the shape of an arc into a region bent radially inwards through a 90{ angle. An outlet guide grille 48 may also be provided to form a flow channel downstream of the turbine wheel 34.

Description

Hand tool machine The invention relates to a hand tool machine according

to the preamble of claim 1.

From US-PS 6,347,985 B1 a hand tool machine is known, which is driven exclusively by the suction air stream of a commercially available vacuum cleaner. As the drive of the known hand tool machine a known Pelton turbine is used, which utilizes the suction air of the vacuum cleaner to set the driven spindle and/or tool in rotation.

The efficiency of the known hand tool machine is relatively low and insufficient use is made of the suction power that may be supplied by vacuum cleaners. High standards of performance and - if provided - of the simultaneous dust extraction from the workpiece cannot therefore be demanded from these hand tool machines.

Advantages of the inventions The invention having the features of claim 1 has the advantage that the hand tool machine in the form of e.g. a sander, which has no electric motor and is operated exclusively by the suction air of a vacuum cleaner, has such high power available for its intended applications that almost completely dust-free sanding occurs with the removal of all dust particles generated during the sanding operation, with the result that a high sanding capacity is combined with extremely effective extraction of the sanding dust.

By virtue of the drive comprising mainly parts made of plastics material, the hand tool machine is particularly light and manoeuvrable.

By virtue of the turbine wheel having at least one channel, which in a first region - downstream - is disposed transversely of the axis of the turbine wheel and leading from radially outside to radially inside and, from there, further downstream runs in the shape of an arc into a region extending approximately parallel to the axis of the turbine wheel, a radial turbine is provided, which is fluidically in its entirety particularly well-tuned and highly effective.

By virtue of the fact that between the air blades of the turbine wheel channels of an identical type are disposed parallel to one another, such that the air is conveyed along the air blades in a radially inward and then axially upward direction, an efficient power transmission of the flowing air to the turbine wheel is ensured.

By virtue of the fact that the rotatable turbine wheel and the rotationally fixed inlet guide grille have a rotationally symmetrical shape, relatively easy manufacture is possible despite their complicated structure.

By virtue of the fact that the turbine wheel comprises an inner, bellshaped carrier body, which carries radially outwardly projecting, dorsalfin-like air blades and a bell-shaped cover disc and/or enveloping bell disposed on radially at the outside substantially parallel to the carrier body, the air guide channels are possible with large, fluidically advantageous radii of curvature.

By virtue of the fact that the air blades on the carrier body have a three-dimensionally helical and/or twist-like shape, the realization of large radii of curvature of the air guide channels is simplified.

By virtue of the fact that the air blades of the turbine wheel, in their radially outer region adjoining the inlet guide grille, uniformly have a blade entry angle of 0 to 30 inclined relative to the radial, a fluidically advantageous transfer from the inlet guide grille to the turbine wheel is provided.

By virtue of the turbine wheel at its downstream end having a blade exit angle of 60 relative to the longitudinal axis, the air mass flow with a rotational flow component is low and so the flow resistance is low.

By virtue of the turbine wheel having a diameter of between and 90 mm and being approximately 30 to 40 mm high, a dimension of the turbine drive that is advantageous for the hand tool machine is achievable.

By virtue of the inlet guide grille embracing the turbine wheel in a ringlike, in particular concentric manner with a low gap clearance, the efficiency of the turbine is improved. To

By virtue of the inlet guide grille comprising a plurality of mutually parallel channels of an identical type, the flow resistance in the inlet guide grille is low.

By virtue of the inlet guide grille having a bell-shaped carrier body, which adjoins the bottom region of the carrier body of the turbine wheel in a flush manner and bulges in a radially outward, arcuately downward manner, an air conduction with large radii of curvature and hence low flow resistance is possible.

By virtue of the fact that the inlet guide grille on its carrier body carries a plurality of fixed, in particular uniformly spaced, fin-like inlet guide bodies, along which the air is deflected from an axial to a radial direction inwards, in particular tangentially, towards the air guide blades of the turbine wheel, the air is conveyed precisely with minimum flow resistance.

By virtue of the fact that the inlet guide grille carries substantially parallel to its carrier body - at the distance of the height of the inlet guide bodies - a bell- shaped enveloping body, fluidically advantageous channels that are closed in a tube-like manner are created in a simple manner.

By virtue of the fact that the inlet guide bodies in a radially inward direction - towards the turbine wheel - have a uniform exit angle relative to the radial of between 60 and 89 , the flow energy of the air is converted particularly well into energy of rotation of the turbine wheel.

By virtue of the fact that the inlet guide bodies at least in the region immediately adjoining the turbine wheel have air guide surfaces inclined by 25 to 50 , preferably 35 , relative to the air blades of the turbine wheel, when they move past one another owing to rotation of the turbine wheel only small pressure peaks are built up, so that the noise development when working with the hand tool machine is low.

By virtue of the fact that the outside diameter of the inlet guide grille is 120 to 150 mm and its height is 20 to mm, particularly advantageous dimensions for the drive of a hand tool machine are found.

By virtue of the fact that there is downstream of the turbine wheel an outlet guide grille, by means of which substantially all of the air quantities with a rotational flow component that flow off the turbine wheel are deflected in axial direction and/or smoothed, the flow resistance is further reduced.

By virtue of the fact that the outlet guide grille forms a flat, discshaped flow channel, which is annular in cross section and interspersed with a plurality of radial, radially disposed outlet guide bodies, the outlet guide grille itself is particularly dimensionally stable, suitable in particular for stiffening the housing and easy to manufacture.

By virtue of the fact that the outlet guide grille - like a wheel - has a hub-shaped central part, which is connected by spoke-like outlet guide bodies to an outer, wheel-rim- like supporting ring, it may by means of its central part To serve as a bearing seat for the turbine wheel and at the same time improve the stability of the housing.

By virtue of the fact that the outlet guide bodies of the outlet guide grille have a boomerang-like cross section, wherein their concave curvature form air guide surfaces having an inlet angle of approximately 50 and having an exit angle of approximately 90 relative to the approach flow direction, rotationally flowing air is deflected and/or smoothed with a particularly low flow loss into linear flow.

By virtue of the outlet guide grille comprising 11 to 39 outlet guide bodies spaced, in particular uniformly, apart from one another, the outlet guide grille is provided in a plurality of variants of differing stability/weight/flow effect, which are usable over a wide range of different requirements.

By virtue of the fact that surfaces of the hand tool machine, in particular of the inlet guide grille and/or of the turbine wheel and/or of the outlet guide grille, that are in contact with the air flow have contoured surface structures that reduce the flow resistance, no dust may cling to the endangered surfaces and reduce the power of the turbine drive.

By virtue of the fact that the housing of the hand tool machine comprises ring- and/or tube-like parts that are connectable to one another by flanges, the housing despite a low dead weight is dimensionally very stable and rugged. o

Drawings There now follows a detailed description of the present invention with reference to an embodiment and the accompanying drawings.

The drawings show: Figure 1 a longitudinal section of an orbital sander according to the invention Figure 2 an exploded view of the orbital sander Figure 3 a side view of a radial turbine wheel Figure 4 a plan view of a radial turbine wheel Figure 5 a perspective view of an inlet guide grille as a detail Figure 6 a plan view of the inlet guide grille according to Figure 5 Figure 7 a cutout of an outlet guide grille Figure 8 the cross section of an outlet guide body.

Description of the embodiment

Figure 1 shows a hand tool machine 10 in the form of an orbital sander. It comprises a housing 12, which in its upper region is designed as a handle, which continues downwards in the form of a waist-like, easy-togrip constriction 14 and then widens into a bell-like region 15.

The housing 12 terminates at the bottom in a straight bottom edge 16, which in its vertical projection downwards forms a triangle with convex sides. Disposed parallel to the bottom edge 16 is a backing pad 18, which is elastically connected to the housing 12 by elastic oscillating bodies 20. The backing pad 18 projects with its smoothing-iron-shaped base radially out beyond the triangular, vertically downwardly projected contour of the bottom edge 16 and has on its underside retaining means for receiving an abrasive sheet 22.

The backing pad 18 on its front, central tip 24 carries a pushbutton 26, after the actuation of which the backing pad 18 is releasable from the housing 12 and/or from a backing pad carrier 28. The backing pad 18 and/or backing pad carrier 28 is drivable in an orbital manner by means of a drive shaft 30 and an eccentric 32 seated in a rotationally fixed manner on the end of said shaft, so that each point of the backing pad 18 and hence each individual abrasive grain of the abrasive sheet 22 describes small circles having the radius of the eccentricity of the eccentric 32, the typical sanding pattern of an orbital sander.

The drive shaft 30 is set in rotation by means of a radial turbine wheel 34 and is rotatably supported in the housing 12 by means of a top and a bottom rolling bearing 40, 42. The drive shaft 30 engages with the eccentric 32 seated on its bottom end into a third rolling bearing 36, which is seated by its outer ring in a rotationally fixed 2 5 manner in the backing pad carrier 28 or in the backing pad 18 itself. The eccentric 32 is integrally connected to a mass-balance weight 38, which serves as unbalance compensation and keeps oscillations of the eccentrically moved backing pad 18 to a certain extent away from the housing 12.

The drive shaft 30 is embraced in a rotationally fixed manner by the centre of the radial turbine wheel 34 and o necessarily follows the rotation of said wheel. The radial turbine wheel 34 has a bell-shaped external contour, which in the inflow region is embraced closely, leaving a small gap, by a fixed inlet guide grille 44, by means of which the inflowing suction air for driving the radial turbine wheel 34 is steadied and/or freed of turbulence and therefore already at the input end improves the efficiency of the radial turbine.

The remaining, adjacent parts of the housing 12 embrace the radial turbine wheel 34 with a small gap, which at the top, at the axial end of the radial turbine wheel 34 runs into an extraction opening 46, which is bent to the right and leads to the outside. At the start of the extraction opening 46, the top end of the radial turbine wheel 34 jointly with the drive shaft 30 is supported axially against an outlet guide grille 48, which serves as a bearing seat of the top rolling bearing 40 of the drive shaft 30. For this purpose, the outlet guide grille 48 is of a star-shaped or cartwheel-shaped design, wherein its hub-like central part 50 carries the rolling bearing 40 of the drive shaft 30 and wherein outlet guide bodies 52, which are spoke-like and/or designed as blades and extend radially outwards from the central part 50, connect the central part 50 to an outer supporting ring 54. Situated between the spoke-like outlet guide bodies 52 (Figure 5) are intermediate spaces 58 for free passage of the spent driving air, which is generated by an external vacuum cleaner.

The outlet guide bodies 52 of the outlet guide grille 48 convert the rotational flow components of the outgoing air, which passes in an axially upward direction out of the To radial turbine wheel 34, into parallel, straight flow components, so that the outgoing air subsequently, having been deflected horizontally through approximately 90 , flows without substantial flow losses and with minimum turbulence through the knee-like extraction opening 46 fashioned in a fluidically advantageous manner with a large radius of curvature and passes into a non-illustrated vacuum cleaner hose connectable to the extraction opening 46, thereby ensuring continuous driving of the turbine wheel 34.

For operation of the hand tool machine 10, outside air flows between the top of the backing pad carrier 28 and the housing bottom edge 16 through to the radial turbine wheel 34, before mixing with the dust extraction air, which is extracted under and through the backing pad 28, in particular through dust holes 56, by virtue of the partial vacuum at the extraction opening 46 and which flows around the radial turbine wheel 34.

The contact between the radial turbine wheel 34, the inlet- and the outlet guide grilles 44, 48 and abrasive dust-laden air may lead there to a wearing and dust-accumulating effect, which may adversely affect the performance and useful life of the drive. To combat this, the surfaces in contact with suction air are structured in particular by means of small, regular depressions in such a way that they have a low flow resistance and a high surface strength.

Figure 2 shows an exploded view of the hand tool machine 10 according to Figure 1. The top region of the housing 12 serves as a handle and together with the moulded waist-like constriction 14 forms a separate housing part 121, from the on rear of which a vacuum cleaner adapter 131 plugged into the not more closely designated extraction opening 46 projects, in viewing direction, to the right.

The housing part 121 is mountable in a vertical flanged connection with an adjoining bell-like housing part 122 situated below it. Disposed between and radially overlapped by the housing parts 121, 122 is the outlet guide grille 48, which is mountable in a vertical flanged connection to the top housing part 121.

The bell-like housing part 122 is adjoined, in viewing direction, in a downward direction by the drive shaft 30.

Its external contour is fashioned in a middle region as a hexagon insert bit 301 and/or in a further possible variant in a knurled and/or smooth manner and is used for positive engagement of the adjoining radial turbine wheel 34, which is situated axially underneath the inlet guide grille 44 and is fastened adherently e.g. by injection moulding to the drive shaft 30.

The inlet guide grille 44 concentrically encircles the radial turbine wheel 34 plus the drive shaft 30 and is installable in a rotationally fixed manner in the bell shaped housing part 122. In said case, the radial turbine wheel 34 - insertable from below - passes through the circular recess 446 of the inlet guide grille 44, wherein in the mounted state the top region of the enveloping body 341 of the radial turbine wheel 34 projects in an upward direction from the circular recess 446. There, it guides the fresh air, which flows in axially from below, radially in towards the centre of the radial turbine To wheel 34, where it may execute its driving effect with great efficiency.

The air, which is drawn in from below in the region of the backing pad 18 through the operation of a vacuum cleaner (not shown) connected to the housing 12, passes from below to the inlet guide grille 44, where it is conveyed in channels 444 in an arc shape radially in towards the radial turbine wheel 34. The juxtaposed channels 444 of an identical type are formed by the radially mutually spaced carrier bodies 440 and the enveloping body 441 as well as the inlet guide bodies 442 extending therebetween and ensure a high air mass flow in the direction of the radial turbine wheel 34.

The inlet guide grille 44 is radially overlapped at the top by the belllike housing part 122, wherein between the housing part 122 and the lowermost region 123 of the housing 12 there is again a vertical flange connection and wherein the lowermost region 123 of the housing 12 comprises two half-shells 124, 125 transversely connectable to one another.

In the lowermost region 123 of the housing 12, the oscillating bodies 20 are insertable between the half shells 124, 125 and mountable in a positively supported manner without further auxiliary means, so that they are supported in accordance with the requirements for operation of the hand tool machine 10.

In viewing direction at the bottom, the oscillating bodies 20 are screwable and/or clippable vertically to the backing pad 18 and/or the backing pad carrier 28, so that To at this point the connection is established between the housing 12 and the backing pad 18. The backing pad carrier 28 at its front tip carries the laterally displaceable pushbutton 26, in the central position of which the backing pad 18 situated underneath is securable so as to be protected against loss. In its lateral swivel positions, the pushbutton 26 releases the backing pad 18 situated underneath.

The frontmost region of the backing pad 18 is designed as a triangular backing pad 181 for equipping with a conventional abrasive sheet in the shape of an equilateral triangle having convex sides and is adjoined, in viewing direction to the right, by the rear region of the backing pad carrier 28, the underside of which is flush with the underside of the triangular backing pad 181. Together with the base of the rear region of the backing pad carrier 28, the entire underside of the backing pad 18 has a contour in the shape of the surface of a smoothing iron that is suitable for the efficient machining of relatively large surfaces, which were too large for a triangular sander of an earlier style of construction.

Furthermore, by virtue of the fact that the front region of the backing pad 18 is in the form of a separate triangular backing pad 181 with a forward-directed tip and is exchangeable and/or easily rotatable and so, where necessary, a less-worn triangular point of the abrasive sheet may be aligned in a forward direction and/or in the event of wear of the triangular abrasive sheet, said sheet may easily be exchanged - in particular jointly with the triangular backing pad 181. To

Inside the housing parts 121, 122 the outlet guide grille 48 is supported at the bottom on the inlet guide grille 44 so as to be axially protected against loss and free of play and therefore simultaneously improves the air conduction.

Figure 3 shows a side view of the radial turbine wheel 34 without the enveloping body 341 shown in Figure 2. The carrier body 340 carries a plurality of air blades 35, which project uniformly upwards like fins and between which in each case a channel 342 extends, in which the air is conveyed at first in the shape of an arc, radially inwards and then later axially upwards, where it emerges at an exit angle a of 60 and is conveyed in the direction of the vacuum cleaner. This exit angle of 60 converts the flow energy of the suction air into a rotation of the radial turbine wheel 34, wherein the suction air after passing the radial turbine wheel 34 may flow with minimum flow resistance to the vacuum cleaner and hence increase the efficiency in the flow system.

The air is supplied radially at the outside through the inlet guide grille 44 to the radial turbine wheel 34 and leaves the latter in axial direction. The air is relieved of tension and deflected in the interior of the radial turbine wheel 34 and therefore delivers power to the shaft 30. For the embodiments, entry angles of 0 and/or of 30 are proposed for the ends of the air blades 35. In said case, the entry angle is to be selected in such a way that the air at rated speed has ideal inflow conditions.

To guarantee adequate deflection, both turbines were constructed with a blade exit angle a of 60 . The height o of the turbine was selected such that, on the one hand, a gentle deflection from the radial to the axial direction occurs and, on the other hand, a significant deflection in meridional direction is additionally possible. The entry angles of the air blades 35 may be between O and 50 and the exit angles between 50 and 75 . The larger the diameter selected for the turbine, the better the power transmission to the shaft and the gentler, i.e. with low flow resistance, the deflection of the air. The size of the turbine is accordingly limited only by the size of the housing, i.e. for a hand-held sander the turbine diameter is usually between 50 and 90 mm.

Figure 4 shows a plan view of Figure 3, wherein the blades ends 350 of the air blades 35 that are inclined at the angle of 30 relative to the radial are clearly visible.

Figure 5 shows a perspective side view of the inlet guide grille 44 without its enveloping body 441, which as such is not removable without destruction. It is therefore possible to discern the ring- and/or belllike design of the carrier body 440 with an inner recess 446. The carrier body carries upwardly projecting, fin-like inlet guide bodies 442, which extend over it in a helically wound manner and thereby form air guide channels 444 with particularly large radii of curvature, which are therefore fluidically very advantageous. The inlet guide body ends 443 of the air guide bodies 442 at the edge of the circular recess 446 are inclined at an angle of 35 relative to the axial, wherein this angle of inclination serves to reduce noise because the edges of the inlet guide bodies 442 and of the blade ends 350 of the air blades 35 that sweep past one another as the radial turbine wheel 34 rotates have only point contact, thereby minimizing shock waves and hence sound peaks and markedly reducing the acoustic emission of the hand tool.

The inlet guide grille 44 has the task of deflecting the air axially from below transversely as tangentially as possible into the radial turbine wheel 34 and hence guaranteeing a high efficiency of the entire system. The inlet guide grille 44 in the form represented below has an exit angle of the inlet guide body 442 relative to the circle normal of approximately 72 degrees. This angle depending on the form of construction may vary between 60 and 75 . If this angle is set too small, the tangential component is smaller and so the efficiency is poorer. If the angle is too large, the air blades 35 of the radial turbine wheel 34 obstruct the actual air channel 444, so that the pressure loss in the inlet guide grille 44 increases and the pressure reduction via the radial turbine wheel 34 decreases. The constructed inlet guide grille 44 moreover has an obliquely designed inlet guide body end 443 adjacent to the blade ends 350 of the radial turbine wheel 34 so that a hard pressure surge at the blade entry edge 351 of the blade end 350 is avoided and "spread" in respect of time. Consequently, the blades of the turbine at all positions sweep past no pronounced edge. The angle of this radially inner inlet guide body end 443 in the illustrated embodiment is cat 35 . In order to achieve an effective noise reduction, the angle should be selected large enough for there to be preferably always two inlet guide body ends 443 in engagement with one air blade 35 of the radial turbine wheel 34 at rated speed, the typical angle of which is between 25 and 72 . This angular To arrangement may conversely naturally also be effected with the radially outer blade ends 350 of the radial turbine wheel 34.

According to Figure 7, the outlet guide grille 48 of a wheel-like design shown in plan view is designed in such a way that the outlet guide bodies 52 extend between the central part 50 and the wheel-rim-like supporting ring 54.

By means of the spoke-like outlet guide bodies 52 the meridional component of the air is cut back to a minimum value and the air is therefore conveyed irrotationally from the hand tool into the vacuum cleaner. The spoke-like air guide surfaces 481 are moreover used as struts from the supporting ring 54 to the hub-like central part 50, which serves as a bearing seat for the top needle bearing of the drive shaft 30.

The outlet guide grille 48 has an approach flow, in viewing direction, from below so that the air passing through the intermediate spaces 58 is deflected at the outlet guide bodies 52 more round, in viewing direction, to the right.

Rotating flow components of the air are directed axially upwards.

Figure 8 shows the boomerang-like cross section of an outlet guide body 52, wherein its concave inner side serves as air guide surface 481. For the entry angle i, as for the exit angle A, in each case an angle of 50 was selected because the air emerging here from the radial turbine wheel 34 has a much higher axial than meridional flow component.

This entry angle in other variants of an outlet guide grille may lie between 40 and 70 and the exit angle may lie between 80 and 100 . The number of outlet guide bodies 52 is to be selected in such a way that the air is conveyed sufficiently well, but the pressure loss in the outlet guide grille remains as low as possible. In the present case, 23 outlet guide bodies were selected, wherein variants having 11 to 39 outlet guide bodies may be advantageous, depending on the application. To

Reference characters hand tool machine 12 housing 131 adapter 14 waist bell-like region 16 bottom edge 18 backing pad oscillating body 22 abrasive sheet 24 tip 26 pushbutton 28 backing pad carrier drive shaft 32 eccentric 33 channel between 2 air blades 34 radial turbine wheel 340 carrier body 341 enveloping body 342 channel 343 exit angle 344 hole for drive shaft 30 air blade 350 blade end 36 rolling bearing in 28 38 mass-balance weight 40, 42 top, bottom rolling bearing for 30 44 inlet guide grille 440 carrier body 441 enveloping body, bell/shell 442 inlet guide body 443 inlet guide body end 444 channels of 44 446 circular recess 46 extraction opening 48 outlet guide grille 480 flow channel of 48 481 air guide surface central part 52 outlet guide body 54 supporting ring 56 dust holes 58 intermediate spaces

Claims

Claims 1. Hand tool machine comprising a housing (12), which carries a

drive unit (30, 34, 44, 48) operable by means of a pressure medium, in particular by suction air, and having a turbine wheel (34) equipped with air blades (35), characterized in that disposed upstream of the turbine wheel (34), in particular radial turbine wheel, is an inlet guide grille (44), which forms at least one channel (33), in particular annular channel, which downstream in a first region runs substantially parallel to the axis of the turbine wheel (34) and upstream - runs in the shape of an arc into a region bent radially inwards through an angle of approximately 90 , so that inflowing, axially directed air is conveyed radially in towards the outer circumference of the turbine wheel (34).
2. Hand tool machine according to claim 1, characterized in that the turbine wheel (34) has at least one channel (342), in particular annular channel, which in a first region - downstream - is disposed transversely of the axis of the turbine wheel (34) and leading radially inwards and upstream - runs in the shape of an arc into a region that extends approximately parallel to the axis of the turbine wheel (34).
3. Hand tool machine according to claim 1 or 2, characterized in that between the air blades (35) a plurality of channels (342) of an identical type are disposed parallel to one another and so that the air is conveyed along the air blades (35) in a radially inward and then axially upward direction.
4. Hand tool machine according to claim 1 - 3, characterized in that the rotatable turbine wheel (34) and the rotationally fixed inlet guide grille (44) have a rotationally symmetrical shape.
5. Hand tool machine according to claim 1 - 4, characterized in that the turbine wheel (34) comprises an inner, bell-shaped carrier body (340), which carries radially outwardly projecting, dorsal-fin-like air blades (35) and a cover disc and/or enveloping bell (341), which is disposed radially at the outside substantially parallel to the carrier body (340).
6. Hand tool machine according to claim 1 - 5, characterized in that the air blades (35) on the carrier body (340) have a helical and/or twisted shape.
7. Hand tool machine according to claim 1 to 6, characterized in that the air blades (35), in their radially outer region adjoining the inlet guide grille (44), uniformly have a blade entry angle of, in sections, 0 to 30 inclined relative to the radial.
8. Hand tool machine according to one of claims 1 to 7, characterized in that the turbine wheel (34) at its top end has a blade exit angle of 60 relative to the longitudinal axis.
9. Hand tool machine according to one of claims 1 to 8, characterized in that the turbine wheel (34) has a diameter of between 50 and 90 mm. No
10. Hand tool machine according to one of claims 1 to 9, characterized in that the turbine wheel (34) is approximately 30 to 40 mm high.
11. Hand tool machine according to claim 1 to 10, characterized in that the inlet guide grille (44) embraces the turbine wheel (34) in a ringlike, in particular concentric manner with a low gap clearance.
12. Hand tool machine according to claim 1 to 11, characterized in that the inlet guide grille (44) comprises a plurality of mutually parallel channels (444) of an identical type.
13. Hand tool machine according to one of claims 1 to 12, characterized in that the inlet guide grille (44) has a bell-shaped carrier body (440), which adjoins the bottom region of the carrier body (340) of the turbine wheel (34) in a flush manner and bulges in a radially outward, arcuately downward manner.
14. Hand tool machine according to one of claims 1 to 13, characterized in that the inlet guide grille (44) on its carrier body (440) carries fixed, in particular uniformly spaced, dorsal-fin-like inlet guide bodies (442), along which the air is deflected from an axial to a radial direction inwards, in particular tangentially, towards the air blades (35) of the turbine wheel (34).
15. Hand tool machine according to one of claims 1 to 14, characterized in that the inlet guide grille (44) carries substantially parallel to its carrier body (440) - at the distance of the height of the inlet guide bodies (442) - a bell-shaped enveloping body (441).
16. Hand tool machine according to one of claims 1 to 15, characterized in that the inlet guide bodies (442) radially inwards - towards the turbine wheel (34) have a uniform exit angle relative to the radial of between 60 and 89 .
17. Hand tool machine according to one of claims 1 to 16, characterized in that the inlet guide bodies (442) at least in the region immediately adjoining the radial turbine wheel (34) have air guide surfaces, which are inclined by 25 to 50 , preferably 35 , relative to the air blades (35) of the turbine wheel (34), so that when they rotate past one another only low pressure peaks and hence only low noise arise.
18. Hand tool machine according to one of claims 1 to 17, characterized in that the outside diameter of the inlet guide grille (44) is 120 to 150 mm, wherein the diameter of its central circular recess (446) is almost equal to the outside diameter of the turbine wheel (34), which is rotatable therein centrally with a low gap clearance, and that the height of the inlet guide grille (44) is 20 to 30 mm.
19. Hand tool machine according to one of the preceding claims, characterized in that disposed downstream of the turbine wheel (34) is an outlet guide grille (48), by means of which air quantities with a rotational flow component that flow off from the turbine wheel (34) are deflected in axial direction.
20. Hand tool machine according to claim 19, characterized in that the outlet guide grille (48) forms a flow channel (480), which is annular in cross section and is interspersed with a plurality of radial, radially disposed outlet guide bodies (52).
21. Hand tool machine according to claim 19 or 20, characterized in that the outlet guide grille (48) like a wheel - has a hub-like central part (50), which is connected by spoke-like outlet guide bodies (52) to an outer, wheel-rim-like supporting ring (54).
22. Hand tool machine according to claim 19, 20 or 21, characterized in that the outlet guide bodies (52) of the outer guide grille (48) have a boomerang-like cross section, wherein their concave curvatures form air guide surfaces (481) having an entry angle of 50 and having an exit angle of 90 relative to the approach flow direction.
23. Hand tool machine according to claim 16 to 18, characterized in that the outlet guide grille (48) has a number of 11 to 39, in particular uniformly mutually spaced outlet guide bodies (52).
24. Hand tool machine according to one of claims 1 to 23, characterized in that surfaces of the drive of the hand tool machine, in particular of the inlet guide grille (44) and/or of the radial turbine wheel (34) and/or of the outlet guide grille (48), that are in At) contact with the air flow have contoured surface structure that reduces the flow resistance.
25. A hand tool machine substantially as herein described with reference to the accompanying drawings.