AU593634B2

AU593634B2 - Compressed air motor

Info

Publication number: AU593634B2
Application number: AU71910/87A
Authority: AU
Inventors: Detlev Brockschmidt; Wolfgang Ebeling
Original assignee: TURMAG TURBO MASCH AG
Current assignee: Turmag Turbo-Maschinen-Ag Nusse & Grafer
Priority date: 1986-04-23
Filing date: 1987-04-23
Publication date: 1990-02-15
Anticipated expiration: 2007-04-23
Also published as: DE3613640A1; DE3613640C2; AU7191087A

Description

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7 AUTALA 593634 Patents Act COMPLETE SPECIFICATION~

(ORIGINAL)

Class Int. Class Application Number: Lodged: 7 Complete Specification Lodged: Accepted: Published: Priority in. .fl,.n.,rflrV tntvm.inxtt A pri11fl2 4Related Art: '.44- *4 4 a a 4'' APPLICANT'S REFERENCE: tur 791/86-Aus Name(s) of Applicant(s): TUJRMAG Turbo-Maschinen-AG Nusse Grafer Address(es) of Applicant(s): Wuppertaler Strasse 3, D 4322"~Spiockhove1 1, FEDERAL REPUBLIC OF GERMANY.

Address for Service is: PHILLIPS ORMONDE and FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Complete Specification for tI.'e inventilr)n entitled: "COMPRESSED AIR MOTOR" Our Ref 50025 POF Code% 43933/57091 The following statement is a full~ description of this invention, including the beat method of performing it known to applicant(s):.

6003j/ 1 t S1A The' present invention relates to a compressed-air motor, in particular for hand drills, with one or several rotors as well as an inner and an outer housing and an exhaust chamber located between them which is in communication with the external atmosphere by means of an exhaust duct.

A known compressed-air motor of this type for a hand drill as disclosed in the German Patent Specification DE-PS 34 07 732 has proved its worth in the manner described therein.

However, the level of noise emitted is a disadvantage. It has been established in the meantime that the fabrication of the outer housing from an entropy-elastic material and the fabrication of the inner housing from a metallic material is t. not an adequate measure in itself. The noise intensity of Sthis compressed-air motor for hand drills is approximately 98 15 6 decibels.

ti tc Starting out on the basis of this state of the art, the object of the present invention is to develop a compressedair motor of the type initially referred to which, while still retaining a high level of performance with outstanding '2 ergonomic features, independent of its construction (slidingvane- or gear-motor), has a nois, intensity which is below 92 decibels.

In combination with the general concept referred to initially, this object is achieved by the present invention S251L by the provision of an exhaust chamber between the rotor (.in the case of a "sridiig-vane-motor) or between the rotors (in the case of agear-motor) and the inner housing and by the provsion "of sickle-shaped' grooves, which are known per se, in the walls of the inner h'ousing, and which become wider and deeper in the direction 'of rotation of the rotor(s) to open into the exhaust chamber, "and by the provision of a fine mesh sieve with a relatively thick wall between hhe pre-exhaust chamber ad the exhhust-collection chamber.

By means of the three fundamental measures, namely the

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provision of a pre-exhaust chamber, of sickle-shaped grooves and a relatively thick-walled sieve, the noise intensity could very surprisingly be reduced to 92 decibels and, depending upon the particular construction of the motor, the noise level could be reduced even further. With such an arrangement it has been found particularly advantageous for the volume of the sickle-shaped grooves to preferably be between 0.005 times and 0.003 times of the chamber volume between the housing and the rotor and for the sieve between the pre-exhaust chamber and the exhaust-collection chamber to preferably have a free flow cross-sectional area which is between 4% and 6% of the total rotor cross-sectional surface area. The chamber volume in the case of a gear motor is understood to be the volume of a tooth space, in contrast to which the chamber volume of a sliding-vane motor is understood to be the space between adjacent .sliding-vanes, the wall of the inner housing and the outer surface of the rotor in the immediate vicinity of the 20 discharge port for the air. Total rotor cross-sectional

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area is to be understood as the cros-sectional area which is derived from a cross-section through the axes of rotation over both rotors within the inner housing.

With the implementation of the sound-absorption measures for the compressed-air motor referred to 4 previously, depending upon the temperature, the relative humidity and the output capacity of the motor, there is a relatively-rapid formation of ice in the vicinity of the fine-mesh sieve. This necessarily leads to a lowering of 30 the air flow and thus of the performance capability of the a compressed-air motor. In order to avoid this and to achieve uniform output capacity of the compressed-air motor, along with good sound absorption, the sieve is preferably fabricated of a sound-reflecting material with good heat conductivity, for example a light metal which is bonded in a good heat-conducting manner to the wall f the inner housing, for example by soldering, welding, casting or by a suitable press-fit connection. Because the wall 39 hL VF {t^r 4 a t *8 of the inner housing is exposed to a heating effect due to air friction forces generated by the rotors, the sieve is also raised to a temperature level which either prevents the formation of ice or gets rid of any ice which may form by almost immediate thawing. Thus it is possible for the required amount of air to flow unimpeded through the sieve which can exert its sound-absorption effect. The sieve preferably has approximately the same thickness as the wall of the inner housing in its immediate vicinity.

With a gear motor of which the direction of rotation may be reversed, it is advantageous for the pre-exhaust chamber, the exhaust-collection chamber and the sieve between them, to be preferably provided at both of two side. outlets of the gear motor. In addition, sickle grooves, which run in both directions of rotation of each rotor, are preferably located between central ducts on each side of the rotors, thus making a total of four sickle grooves which are preferably enlarged in the respective direction of rotation towards the closest 20 central duct. In this way, independent of the direction of rotation of the rotors of the compressed air-motor, the direction of rotation of which may be reversed as desired, the same sound-absorption measures are implemented. The central ducts of the compressed aiz-motor, the direction of rotation of the rotors of which may be reversed as desired, advantageously possess a conical constriction which increases as they pass from one end of the inner housing to run parallel to the longitudinal axes of the rotors. In the immediate vicinity of these central ducts, 30 aid separated from them by an appropriate partition, there is preferably a relatively flat expansion duct which gradually increases in cross-sectional area.

For additional sound absorption, it is advantageous for the exhaust-collection chamber to be formed partly of flat continuous intermediate spaces between the inner and outer housings and partly of box-shaped or spherical expansion chambers. The inner housing of the motor possesses pre-exhaust openings which are known per se (see 39. -3- *8t4 e 4 4 8 8 4 ai 4r4 4 I C 88 0 ii; i ;1 1 o German Patent Specification DE-PS 34 07 732) in the form of small drilled holes or slots, the optimal location of which, in the direction of rotation of the rotor involved, may be determined empirically, and which may be, by way of said flat continuous intermediate spaces, in communication t w $9 9 9 t 99

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0 -3X- 77~ rn-rn---- 4 with the box-like or spherical expansion chambers of the exhaust-collection chamber I;y way of the said flat c;-ontinuou i npermiTarel aepc The exhaust-collection chamber can only fulfill its noisereduction function if it is separated acoustically from the external atmosphere but, at the same time, there must be the least possible hindrance to the flow of exhaust air to the outside. This is ensured primarily by provision of an airexhaust duct in which the air-flow is first of all accelerated and subsequently slowed down in a conical enlargement of the duct. It is advantage for the end of the air-exhaust duct to be flared out like the mouth of a trumpet so that it contributes to further slowing down and dispersion of the air stream and thus to further noise reduction.

poo** 15 In order further to reduce the noise intensity it has been e** found to be an advantage to provide an additional sieve between the exhaust-collection chamber and the air-exhaust diuct. Furthermore, the air-exhaust duct may be configured as an absorption-silencer, or as a reflection-silencer in the form of a serial low-pass filter, of a branched high-pass I filter or of an interference-silencer. In the case of absorptio -silencers, the inner wall consists of soundabsorbent )material which therefore absorbs the acoustic pressure, 'whereas the reflection-silencers, as a general rule, consist of sound-reflecting material. Their effect is essentially based upon the superimposition of phase-displaced Sacoustic waves which, when the phase displacement is approximately 1800 with the same amplitude and wave-length, are cancelled out' because of the occurrence of interference phenomena., A compressed-air motor of the type des ribed previously, i 10 ho veespecially designed for use with a and-drill, is ch irnft- P i d h" hfac~ tht-- the air-exhaust duct which connects the exhaust-collection chamber with the -external atmosphere is located 1 1-1.a urGr kno,.n per a. in one of the hand-grips of the hand-drill. It is advantageous for this ;i;~;lt-~tL~IU~ hand-grip which contains the air-exhaust duct to be detachable from the outer housing of the hand-drill, in particular by having a screw-thread connection so that it can be screwed off, and it should also cons st of entropyelastic material. In order to be able to operate this drill manually after the hand-grip has been removed, especially with the use of 'a drill-column such as that commonly employed in mining operations, the discharge opening for the air in the outer housing, after the ha 'd-grip has been taken off, should be able to be connected to one arm of a hollow retaining yoke which is provided with a large number of small discharge openings. In this way these numerous discharge openings act as an additional sieve which corresponds, to a certain extent, to the previously described form of embodiment including the hand-grip where the additional sieve is S located between the exhaust-collection chamber and the air- O*49* q*0 a exhaust duct.

The retaining yoke can be connected by way of its second arm to a grip nozzle, or union, on the outer housing which, when the drill is being used manually, provides the connection foi the second hand-grip which is likewise designed to be detachble. This second arm of the hollow retaining yoke can be S connected in a pressure-proof manner with the outer housing S i~n order to provide a compressed-air inlet to the compressedcr 5 air motor and it is provided at another point some distance away with a nozzle, or union, for connection to the supply pipeline for compressed air. In this way, the unusual hollow form of the 'retaining yoke, which is required for a noisereducing discharge of the air from the exhaust-collection chamber-into the external atmosphere, can be exploited for an ergonomically fa orable supply of compressed air to the compressed-air motor. With such an arrangement, it is advante- #ageous for the arm'of the retaining yoke, which is associated with the air outlet,'to be configured as an absorption- or reflection-silencer a 0 y f f :he nP ClaJms and will now be described in greater a 4'~e T The following description refers in more detail to the various features of the compressed-air motor of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the compressed-air motor is illustrated in preferred embodiments. It is to be understood that the compressed-air motor of the present invention is not limited to the preferred embodiments as illustrated in the drawings.

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4 wW *16 6 tail with rfrn t the accompanying drawing. hr is Fig. 1 an elevation, partly in section along the line I I shown in Fig. 3, of a compressed-air motor in the form of a gear,,motor mounted in a hand-drill, Fig. 2 an elevation, partly in section, of a compressed-air motor in the form of a sliding-vane motor mounted in a handdrill, Fig. 3 a section along the line III III through the gear motor shown in Fig. 1, Fig. 4 a section along line IV IV in Fig. 5 through a compressed air-motor, in which the direction of rotation of the rotors may be reversed as desired, with pre-exhaust chambers, exhaust-collection chambers, sieves and the central l ducts between the two rotors located on both sides, S Fig. 5 a section along line V V in Fig. 4, Fig. 6 a section a.ong line VI VI in Fig. t t t Fig. 7 a form of embodiment of the new type of compressed-air S motor in a rotary drill with a retaining yoke containing the air ducts instead of the hand-grips, showing the silencer outlet openings and the pressure-proof seal on the other arm S of the yok partly in section, and S Fig. 8 a side elevation of the motor depicted in Fig. 7 with a hand-grip located on the rear side of the outer housing.

The compressed-air motor illustrated in Figures 1 to 3 is provided with an inner housing an outer housing with an exhaust-collection chamber (13) located between them which is in communication with the ex rnal atmosphere by way Sof an air-exhaust duct In the embodiment depicted in S/ /f Figures: 1 and 3, the compressed-air motor is configured as a o i 7? CIC T i "I 1 l -l O 0t L 7 gear motor with two rotors (6 and whereas the compressedair motor with only one rotor depicted in Figure 2 is configured as a sliding-vane motor, the vanes of which have their outer edges forced 'against the inside surface of the wall of the inner housing by means of springs, by hydraulic pressure or by pressure of the compressed air which is introduced through connecting ducts which are not depicted, and also by their own centrifugal force during rotation.

f pre'-eslhowo tln a-n-iann- -i-a h poPtnt i nvpnt nn an exhalst chamber is provided between the rotor in the case of the sliding-vane motor, or between the rotors in the case of the gear motor, and the wall of the inner housing and there are also sickle grooves in the wall (12) of the "*1t inner housing which run in the direction of rotation of the rotor(s) 7, 8)- as shown by the arrows where these grooves are gradually enlarged in cross-section in the direction towards the pre- xhaust chamber (10) into which they open. There is also a fine-mesh sieve (14) with a relatively thick wall located between the pre-exhaust chamber and the exhaust-collection chamber (13).

4,£41 4 t The volume of the sickle grooves (11) is approximately between 0.005 and 0.003 times the volume of the chamber of the associated rotors 7, Here it is understood by the chamber volume, in the case of the gear motor in accordance with Figure 1, that this is the volume of a tooth space over the total length of the relevant rotor. In the case of the Ssliding-vane mobtpr in accordance with Figure 2, the chamber volume is understood to be the hatched region (16) between two sliding vanes (17, 18) immediately before the start of the sickle groove (11).

The sieve (14) between the pre-exhaust chibber (10) and the exhaust-collection chamber (13) possesses a free flow crosse sectional area which is the sum of all Lts flow-through openings (19) from 4% up to 6% of the total rotor crosssectional area. By rotor cross-sectional area, (20) in 0I r rr

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/v/l^A <23 8 accordance with Fig. 1 and (23) in accordance with Fig. 2, is to be understood the free cross-sectional area of the inner 0 housing through the longitudinal axis (24) or axes (21, 22) of the rotors.

,The sieve (14) consists of a sound-reflecting material with good heat conductivity, for example a light metal which is bonded in a, good heat-conducting manner to the adjacent metal wall (25) of the inner housing for example by soldering, by welding, by a suitable press-fit connection or by casting, as depicted in Figures 1, 2 and 4.

As may be seen in Figures I, 2 and 4, the sieve (14) has approximately the same thickness as the adjacent wall (25) of the inner housing .n its immediate vicinity.

S. In the case of the gear motor depicted in Figure 4, of which the direction of rotation may be reversed, the pre- Sexhaust chamber the exhaust-collection chamber (13), the sieve (14) between these two chambers are all duplicated on both sides at the exhaust discharge ports. Between the two rotors 7) as is usually the case with a gear motor of which the direction of rotation may be reversed central S ducts (27) are located on both sides andf in accordance with Figure 5, these ducts are gradually constricted in a conical manner, starting from one side (28) of the outer housing (3) and running parallel to the longitudinal axes (21, 22) of the S rotors Running in each of the directions of rotation )s shown by the arrows (29, 30) or (31, 32) for each of the 4 Sotors 7) there is a sickle groove (33, 34) or (35, 36) each of which. a .n ccrrdance with Patent Claim l-f increases in cross-sectional area to open into the pre-exhaust chamber There"is also an additional sickle groove (37, 38) or (39, 40), in the wall of the inner housing associated with each of the rotors 7) in each of the directions of rotation as indicated Gy'the arrows (29, 30) or (31, 32).

hus there are four sickle grooves associated with each of 3 the rtors making a grand total of eight sickle i'Vc; grooves, where the sickle grooves (33, 35, 37, 39) are i- -fi.~aj, h^ t w 1 '1 9 associated with the rotor and the sickle grooves (34, 36, 38, 40) are associated with the rotor It can be seen most clearly from Figures 1 and 2 that the exhaust-collection chamber (13) is formed partly by flat continuous intermediate spaces (41) between the inner housing and the outer housing and partly by box-shaped or spherical-shaped expansion spaces (42), In the case of the gear motor in accordance with Figure 1, the inner housing possesses pre-exhaust openings the optimal location af which, in relation to the direction of rotation shown by the arrow (15) for the relevant rotor may be determined empirically, and which are in communication with the box-shaped or spherical-shaped expansion space (42) of the exhaust-collection chamber (13) by way of one of the flat intermediate spaces For further reduction of the S noise intensity, there is an additional sieve (44) located between the exhaust-collection chamber (13) and the airexhaust duct as shown in Figure 1.

The cIOm nent parts of Figure 3 which correspond to those shown in Figure 1 are indicated by means of the same refer- SP i ence numerals. With regard to the designation and function of S the additional components depicted in Figure 3, attention is drawn to the disclosures in the German Patent Specification DE-PS 34 07 732, These components are not objects of this S present invention.

e t 0 SThe cair-exhaust duct in accordance with Figures 1 to 3, S may be configured as an absorption-silencer, or as a reflee- *tion-silencer in the form of a serial low-pass filter, of a branched high-pass filter or of an interference-silencer. In the direction towards its outlet end the air-exhaust duct is expanded conically and preferably flared out like the mouth of a trumpet. The outer housing consists of an entropy-elastic material. As may be seen, especially in Priguros 3 and 4, at least a portion of the exhaust-collection chamber (13) is covered by a sound-absorbent inna; lining 0 4.r i o l~M (46) made, for uxample, from a fibrous material, from a foamed material, or similar substance and the lining is held in position by means of perforated sheeting The perforated sheeting" (47) may be recognized easily, especially in elevation in PFgures 1 and 2.

In the case of the gear motor (26) with reversible direction of rotation, in accordance with Figure 5, there is a flat, expansion duct (50) which enlarges conically in the direction of flow of the air and which is located alongside the intermediate partition wall (48) which separates it from the exhaust-collection chamber as well as alongside the wall of the central duct and this likewise contributes to reduction of the noise intensity.

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rir~ As may be seen from Figures 1 to 3, the compressed-air motor which is disclosed therein, is especially suitable for use with a hand-drill. Such being the case, the air-exhaust duct through which the exhaust-collection chamber is in communication with the external atmosphere is located in one hand-g rip (51) of the hand-drill, This hand-grip (51) with the air-exhaust duct in the cases illustrated, is detachable from the outer housing by means of the screwthread (52) and is fabricated, for preference, If entropy-elastic material. This set-up is clearly recog, ~Vk in Figure 3.

f2i Because of this configuration, the dimensions of the handdrill may be reduced to a minimum in an ergonomically favorable manner when it is supported on a drill-column and if the hand-grip (59) on the right-hand side, which forms the valve for the compressed air, is also designed to be detachable.

3 0 However, with this design, the exhaust duct which came after the exhaust-collection chamber (13) is now no longer present and thus an important member of the chais reduction devices is absent.

For this reason, provision is made, in a fur of the invention, for a retaining yoke (55) of P:

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0 i 511 ruction to have one arm (54) which may be connected to the exhaust opening (53) of the outer housing to act as the air-exhaust duct. It is advantageous to provide a plurality of openings (56) in the wall of the arm (54) of the retaining yoke (55) to reduce noise from the air exhaust.

This hollow construction of the retaining yoke (55) makes it possible, in an ergonomically-favorable manner in line with the object of the invention, to utilize the second arm (57) of the yoke as the duct for the supply of compressed air to the drill when the retaining yoke (55) is able to be connected to nozzle (58) of the outer housing which is also used for connection of the second hand-grip which S is also detachable, but which is attached as depicted in Figures i to 3, when the drill is used manually.

o l The second arm (57) of the hollow retaining yoke in the case of the compressed-air motor can be connected to the outer housing by way of the O-ring seals (61) and the hollow screw-threaded plug to provide the inlet duct (60) for compressed air and, at some distance away from this 2 poiint, it is provided with a nozzle (62) for connection to the pipeline (not depicted) for the supply of compressed air.

The screw-threaded collars (63, 64) at either end of the outer housing for attachment of the hand-grips (51, 59) f or of the two arms (54, 57) of the retaining yoke (55) are S located on a comnon longitudinal axis (65) which intersects the axis depicted in Figures 3 and 8, of the output drive shaft (70) of the compressed-air motor at right angles, so that the outer housing may be rotated around Sthe common axis (65) of the screw-threaded collars (63, 64).

The arm (54) of the hollow retaining yoke which has the air exha ust (53L incorporated in it, is advantageously design(d to act ,s an absorption- or reflection-silencer.

According to Figure 8, the outer housing of the compressed-air motor is provided with an additional means of couling (66) for the attachment of an additional handgrip (67) which is advantageously attached by the coupling J S" -)m means (66) in this case with threaded screws in four tapped holes to the rear side (68) of the outer housing of the compressed-air motor facing away from the drill (not depicted in the Figure).

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Claims

9. ,ga THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. Compressed-air motor, in particular for hand drills, with one or several rotors as well as an inner and an outer housing and an exhaust-collection chamber located between them which is in communication with the external atmosphere by means of an air-exhaust duct, wherein there is a pre-exhaust chamber between the rotor (in the case of sliding-vane-motor) or between the rotors (in the case of a gear-motor) and the inner housing and there are sickle-shaped grooves in the walls of the inner housing, and which become wider and deeper in the direction of rotation of the rotor(s) to open into the pre-exhaust chamber, and there is a fine-mesh sieve with a relatively thick wall between the pre-exhaust chamber and the exhaust-collection chamber. 2. Compressed-air motor in accordance with Claim 1, wherein the volume of the sickle-shaped grooves is between 0.005 times and 0.003 times of the chamber volume between the housing and the rotor and wherein the sieve 20 between pre-exhust chamber and exhaust-collection chamber has a free flo cross-sectional area which is between 4% and 6% of the total rotor cross-sectional surface area. 3. Compressed-air motor in accordance with Claim 1 or 2, wherein the sieve is fabricated from a sound-reflecting material with good heat conductivity, for example a light metal which is bonded in good heat-conducting manner to the wall of the inner housing,, for example by toldering, welding, casting or by a suitable press-fit connection. 4. Compressed-air motor in accordance with any one of Claims 1 to 3, wherein the sieve has approximately the same thickness as the wall of the inner housing in its immediate vicinity. Compressed-air motor in accordance with any one of Claims 1 to 4, wherein, with a gear motor of which the direction of rotation may be reversed, the pre-exhaust chamber, the exhaust-collection chamber and the sieve between them, are arranged at both of two side outlets of -13- *441 A 9* 1 A 49 *r S 94f 4 A 9444r *9e *9 9 A 4 4 i' I-) t "V >r .oa W VIM 4 frt P. *I Sii 4 f ft 4, aP fttttf 4 f 1 said gear motor. 6. Compressed-air motor in accordance with Claim wherein sickle grooves, which run in both directions of rotation of each rotor, are located between central ducts on each side of the rotors and said sickle grooves increase in cross-sectional area in the respective direction of rotation towards the closest central duct. 7. Compressed-air motor in accordance with Claim or 6, wherein the central ducts display a conical constriction which increases as they pass from one end of the inner housing and run parallel to the longitudinal axes of the rotors. 8. Compressed-air motor in accordance with any one of Claims 1 to 7, wherein the exhaust-collection chamber is formed partly of flat continuous intermediate spaces between the inner and outer housing and partly of box-shaped or spherical expansion chambers between the inner and outer housing. 9. Compressed-air motor in accordance with Claim 20 8, wherein the inner housing of the motor possesses pre-exhaust openings in the form of small drilled holes or slots, the optimal location of which, in the direction of rotation of the rotor involved, is determined empirically, and which are, by way of said flat continuous intermediate spaces, in communication with the box-like or spherical expansion chambers of the exhaust-collection chamber.
10. Compressed-air motor in accordance with any one of Claims 1 to wherein an additional sieve is located between the exhaust-collection chamber and the 30 air-exhaust duct.
11. Compressed-air motor in accordance with any one of Claims 1 to 10, wherein the air-exhaust duct is configured as an absorption-silencer, or as a reflection-silencer in the form -14- ,r" 4 of a serial low-pass filter, of a branched high-pass filter or of an interference-silencer.
12. Compressed-air motor in accordance with any one of Claims 1 to 11, wherein the air-exhaust duct is enlarged conically in the direction towards its discharge end.
13. Compressed-air motor in accordance with any one of Claims 1 to 12, wherein the discharge end of the air-exhaust duct is flared out like the mouth of a trumpet.
14. Compressed-air motor in accordance with any one of Claims T0 1 to 13, wherein the outer housing is fabricated from an S entropy-elastic material in a marnnor know- per-p. S 15. Compressed-air motor in accordance with any one of Claims 1 to 14, wherein a portion of the exhaust-collection chamber is covered by a sound-absorbent inner lining made, for 15 example, from a fibrous material, from a foamed material, or from 'a similar substance, and said lining is held in position o by means of perforated sheeting. *4 a) 4 .9 44 as a a* a, a a. 4 0 4.) a
16. Compressed-air motor in accordance with any one of Claims 1 to wherein the air-exhaust duct which connects the exhaust-collection chamber with the external atmosphere is located ina i f i. of the hand-dri^44;"
17. Compressed-air motor in accordance with Claim 16, wherein the hand-grip with the air-exhaust duct is detachable from the outer housing, in particular by means of a screw-thread, and is fabricated from an entropy-elastic material.
18. Compressed-air motor in accordance with Claim 12 or 13, whereih a retaining yoke of hollow construction has one arm conneced to the exhaust opening of e outer housing to act 3 -as .4hocompressed-air-exhaust duct and there is a plurality f small openings in the wall of said rm. E Ira a I i(l\ 3 .j ~6c 1. n rt h
19. Compressed-air motor in accordance with claim 18, wherein the retaining yoke can be connected by way of a second arm to a grip nozzle, or union on the outer housing which provides the connection for a second hand-grip which is likewise designed to be detachable. Compressed-air motor in accordance with claim 19, wherein the second arm of the hollow retaining yoke to the compressed-air motor 4,s connected tightly with the outer housing and is provided at another point some distance away with a tube nozzle, for connection to the supply pipeline for compressed air.
21. Compressed-air motor in accordance with claim 19 or 20, wherein screw-threaded collars at either end of the outer housing for attachment of two arms of the retaining yoke are located on a common longitudinal axis which intersects the axes of the compressed-air motor at right angles, so that the outer housing may be rotated around the common axis of the screw-threaded collars.
22. Compressed-air motor in accordance with any one of Claims 18 to 21, wherein the arm of the hollow retaining yoke containing the air-exhaust duct is in the nature of an absorption- or reflection-silencer.
23. Compressed-air motor in accordance with any one of Claims 1 to 22, wherein the outer housing of the compressed-air motor is provided with an additional means of coupling for the attachment of an additional detachable hand-grip.
24. Compressed-air motor, substantially as hereinbefore described with reference to any one of the 30 embodiments as shown in the accompanying drawings. 9. .4 q -4 9 9 i i *I 39 PHILLIPS ORMONDE FITZPATRICK Attorneys for: TURMAG Turbo-Maschinen-AG Nusse Grafer -16- B 1 i 1 i i:i VHF' 0228b P""~YLL~IYI IPliC~ L~ r a t,