GB2425504A

GB2425504A - Hand machine tool striking mechanism unit

Info

Publication number: GB2425504A
Application number: GB0608171A
Authority: GB
Inventors: Gerhard Meixner; Thilo Henke; Juergen Lennartz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-04-28
Filing date: 2006-04-25
Publication date: 2006-11-01
Anticipated expiration: 2026-04-25
Also published as: US20060243467A1; GB2425504B; CN1853868A; CN100592964C; GB0608171D0; DE102005019711A1

Abstract

A hand machine tool striking mechanism unit comprises a beater unit 10a which can be driven by means of a piston 12a via a gas volume 14a, and has a striking mechanism parameter. The striking mechanism parameter is formed by a maximum beater surface measurement 16a to the power three divided by the beater unit mass 18a, and is greater than 200mm<3>/g. Preferably the striking mechanism parameter is also less than 2000mm<3>/g.

Description

Hand machine tool striking mechanism unit

Prior art

The invention is based in particular on a hand machine tool striking mechanism unit according to the preamble of claim 1.

Hand machine tool striking mechanism units are already known with a beater unit which can be driven by means of a piston via a gas volume. The beater unit is constructed as substantially cylindrical and has a round beater unit surface or operating surface in the direction of the gas volume. In order to achieve as far as possible a compact hand machine tool striking mechanism unit, a striking mechanism parameter, formed by a maximum beater unit surface measurement, such as in particular by a maximum beater unit surface diameter or beater unit operating surface diameter, power three divided by the beater unit mass, amounts as standard to approximately 160 mm3/g. A maximum pressure of approximately 15 bar then ensues in operation in the gas volume.

Advantages of the invention The invention is based on a hand machine tool striking mechanism unit with a beater unit which can be driven by means of a piston via a gas volume.

It is proposed that a striking mechanism parameter, formed by the maximum beater unit surface measurement power three divided by the beater unit mass, is greater than 200 min3/g, preferably greater than 220 mrn3/g and particularly preferably greater than 240 mrn3/g. In this case a "beater unit surface measurement" is to be understood in particular as a straight line diagonal of a surface - preferably of an operating surface pointing towards the piston or interacting with the gas volume - such as a diameter, an elliptical length, a polygonal diagonal, etc. By departing from the established doctrine of executing a hand machine tool unit from the point of view of compactness with a striking mechanism parameter of approximately 160 mrn3/g, in fact with a striking mechanism parameter greater than 200 mrn3/g, preferably greater than 220 mm3/g and particularly preferably greater than 240 mrn3/g, in particular valuable properties in respect of a reduction in heat development in the striking mechanism can be achieved. dditionally, a corresponding construction according to the invention also has a particularly advantageous effect on the convenience properties of the hand machine tool striking mechanism unit.

The heat development can advantageously be further lowered and the convenience properties advantageously further increased if the striking mechanism parameter is greater than 280 rnm3/g, preferably greater than 320 mm3/g and particularly preferably greater than 380 3/g.

If the striking mechanism parameter is smaller than 2000 mrn3/g, an acceptable construction space can additionally be achieved with particularly low heat development and particularly great convenience.

It is further proposed that the hand machine tool striking mechanism unit is configured in such a way that in operation a maximum gas pressure in the gas volume is less than 10 bar, advantageously less than 8 bar and particularly advantageously less than 6 bar, which also has a particularly advantageous effect on the heat development and the convenience properties of the hand machine tool striking mechanism unit. A corresponding pressure reduction compared with known hand machine tool striking mechanism units can be achieved in particular by a configuration of the hand machine tool striking mechanism unit with a striking mechanism parameter according to the invention, but additionally or alternatively also by other measures appearing practical to the person skilled in the art.

The beater unit and the piston may have different operating surfaces appearing practical to the person skilled in the art, such as, for example, angular, elliptical, symmetrical or unsymmetrical operating surfaces, etc. The "operating surface" of the beater unit is to be understood in this case in particular as the face of the beater unit facing the piston and the "operating surface" of the piston as the face of the piston facing the beater unit or the faces interacting with the gas volume. However, a maximum beater unit operating surface measurement advantageously differs from a minimum beater unit operating surface measurement by less than 30% and particularly advantageously by less than 20%, however the beater unit and/or the piston particularly preferably has a round operating surface, whereby the hand machine tool beater unit can be produced structurally particularly simply and at a reasonable price. The maximum beater unit surface measurement is in this case preferably formed by a diameter of the operating surface of the beater unit. The hand machine tool striking mechanism unit is further advantageously configured in its dimensions in such a way that in a so- called striking position, in which the beater unit in operation impacts on a tool or on a striking pin and the piston is in its front end position facing the beater unit, a distance between the operating surface of the piston and the operating surface of the beater unit corresponds at least substantially to approximately the maximum beater unit surface measurement or the diameter of the operating surface of the beater unit, i.e. has a difference advantageously of less than 30%, preferably less than 20% and preferred less than 10%, which in particular explains why the beater unit surface measurement enters into the calculation of the beating mechanism parameter not only power two but power three.

Preferably costs can also be saved if the operating surfaces of the piston and the beater unit at least substantially correspond to one another, i.e. have a difference, in particular a difference in size, of less than 5%. However, the operating surfaces of the piston and the beater unit can basically also be constructed differently in size and shape.

It is further proposed that the hand machine tool striking mechanism unit has an eccentric drive positioned on one side and/or a striking mechanism transmission with cylindrical gear teeth only, allowing reasonably priced components, configured advantageously in terms of their convenience properties, to be used. The solution according to the invention is, however, also suitable for hand machine tools with drives alternative to an eccentric drive, such as in particular for hand machine tools with a so-called wobble shaft, etc. In a further configuration of the invention it is proposed that the hand machine tool striking mechanism unit comprises at least one control aperture, provided for controlling the gas volume and coupled to a machinery space. "Provided" is here to be understood in particular specifically as "equipped" and/or "configured". "Coupled" is to be understood in this context in particular as a fludic coupling, so the gas of the gas volume can flow via the control aperture into the machinery space and/or the gas volume can be fed with gas from the machinery space. A "machinery space" is further to be understood as in particular a transmission space, a lubricating oil space, a motor space, etc. and/or in particular a space partitioned off from the outside, i.e. from the environment of a hand machine tool, at least in one respect, and, for example, connected to the hand machine tool environment at least substantially by pressure equalising means only.

By appropriate configuration at least one direct gas exchange between the gas volume and the hand machine tool environment and losses in convenience caused thereby and also environmental pollution can be avoided.

It is further proposed that the beater unit comprises at least one decoupling means, provided for dimensional decoupling of a beater basic body of the beater unit, and comprises at least one coupling between the decoupling means and the beater basic body, provided for coupling the beater basic body and the decoupling means during a flight phase of the beater basic body at least largely synchronously. A "beater basic body" is to be understood in particular as a part of the beater unit constituting at least the bulk of the mass of the beater unit and/or acting on a tool directly or via a striking pin. A "dimensional decoupling" is to be understood in particular as a decoupling in at least one respect, so that in respect of the dimension of the beater basic body preferably at least one degree of freedom arises. A "flight phase" is to be understood in this context in particular as a movement of the beater basic body, caused by the piston, in the direction of a tool or in the direction of a striking pin and in the direction of the piston itself.

By appropriate configuration according to the invention the beater basic body and/or the entire beater unit can be further improved in respect of its function at least from one point of view. As well as the beater unit, a striking pin unit in particular may also comprise a decoupling means for dimensional decoupling of a striking pin basic body, whereby further degrees of freedom can also be created for the striking pin unit in respect of its configuration. A "striking pin basic body" is likewise to be understood in this context in particular as a part of the striking pin unit constituting at least the bulk of the mass of the striking pin unit and/or interacting directly with a tool and/or with the beater unit.

The decoupling means can be constructed in various ways, though this is preferably arranged in the area of an outer circumference of the beater basic body, so its outer contour can be configured more freely in at least one respect than without decoupling means, for example the decoupling means may be advantageously used to secure a sealing means, so in the area of the sealing means the beater basic body can be more freely configured in respect of its dimensions, etc. Particularly advantageously the decoupling means is provided, however, for at least partial decoupling of an outer dimension of the beater basic body from a guide means of the beater unit or the decoupling means is advantageously arranged between the beater basic body and a guide means of the beater unit. A "guide means" is to be understood in this context in particular as a means in which the beater unit is guided, such as in particular a tubular component. The beater unit mass and a beater basic body geometry can be particularly advantageously coordinated independently of a piston surface and an air cushion operating surface or an air cushion geometry and an advantageous striking mechanism parameter, formed by the maximum beater unit surface measurement power three divided by the beater unit mass can easily be achieved.

The decoupling means may be produced of various materials appearing practical to the person skilled in the art, such as advantageously of a self-lubricating material, a plastics material, a metal, a composite material, etc. In a further configuration of the invention it is proposed that the decoupling means is produced from a lighter material than the beater basic body, whereby advantageously a small mass of the beater unit can be achieved with a large operating surface.

It is further proposed that the coupling and/or the decoupling means is constructed at least partially as vibration-absorbing. "At least partially vibration- absorbing" is to be understood in particular in that via the coupling and/or the decoupling means itself in operation a lower vibration transmission takes place than inside a one-part metal body over a corresponding section and indeed in particular in that a vibrationabsorbing and/or vibration-insulating relative movement between the decoupling means and the beater basic body and/or inside the decoupling body is enabled, for example via positive locking and/or by means of an elastic material, so in particular a vibration of the beater basic body in operation arrives at a point of the decoupling means transmitting the vibration to the outside at least 10%, preferably more than 30% and particularly preferably more than 60% absorbed. Convenience can be further increased by appropriate configuration.

If the coupling comprises at least one connection produced by vulcanising on, an advantageous secure connection, in particular between the beater basic body and the decoupling means, and simultaneously advantageous vibration absorption, can be easily achieved.

If the decoupling means has at least one guide surface, the decoupling means can advantageously be used to improve the guidance and/or to reduce the friction, for example by making it of a self-lubricating material.

If the decoupling means has at least two guide surfaces spaced apart in the axial direction, weight can be saved and advantageous guiding can be ensured.

It is further proposed that the beater unit has at least one guide rib, whereby the beater unit can be guided in a guide means with a large internal measurement and yet advantageously a small beater unit mass can be achieved.

If the beater unit is constructed as stepped, degrees of freedom can again be achieved in respect of its mass and outer shape. A "stepped beater unit" is to be understood in this context in particular in that the beater unit has different guide dimensions, in particular different guide diameters, owing to its stepped design. A parameter, formed by a theoretical diameter with an unstepped cylindrical configuration with identical mass divided by a maximum beater unit surface measurement, is advantageously smaller than 0.95, preferably smaller than 0.8 and particularly preferably smaller than 0.7, and a parameter, formed by a length of the beater unit divided by a maximum beater unit surface measurement, is advantageously smaller than 3, preferably smaller than 2. 5 and particularly preferably smaller than 2.

Drawings Further advantages emerge from the following description of the drawings. In the drawings embodiment examples of the invention are illustrated. The drawings, the description and the claims contain numerous features in combination.

The person skilled in the art will advantageously also look at the features individually and assemble them into practical further combinations.

In the drawings: Fig. 1 shows a hand machine tool, formed by a hammer drill, with a schematically illustrated hand machine tool striking mechanism unit; Fig. 2 shows a detail of an alternative hand machine tool striking mechanism unit with a beater unit comprising a vulcanised on decoupling means; Fig. 3 shows a detail of an alternative hand machine tool striking mechanism unit with a beater unit comprising a decoupling means coupled by positive locking; Fig. 4 shows a detail of an alternative hand machine tool striking mechanism unit with a stepped beater unit; Fig. 5 shows a detail of an alternative hand machine tool striking mechanism unit with a further stepped striking mechanism unit; Fig. 6 shows a detail of an alternative hand machine tool striking mechanism unit with a decoupling means forming a holding function for a sealing means; Fig. 7 shows a detail of an alternative hand machine tool striking mechanism unit with a further decoupling means forming a holding function for a sealing means; Fig. 8 shows a detail of an alternative hand machine tool striking mechanism unit with a beater unit comprising a stepped beater basic body without decoupling means; Fig. 9 shows a detail of an alternative hand machine tool striking mechanism unit with a beater unit comprising guide ribs; Fig. 10 shows the beater unit from Fig. 9 in a direction marked by X in Fig. 9; Fig. iT shows a detail of an alternative hand machine tool striking mechanism unit with a pot-shaped beater unit; and Fig. 12 shows a detail of an alternative hand machine tool striking mechanism unit with a further pot-shaped beater unit.

Description of the embodiment examples

Fig. 1 shows a hand machine tool formed by a hammer drill, with a hand machine tool striking mechanism unit according to the invention. The hand machine tool striking mechanism unit comprises a beater unit lOa, which can be driven by a piston 12a via a gas volume l4a. The beater unit l0a and the piston 12a are guided in a joint cylindrical guide means 32a, formed by a hammer tube and have corresponding operating surfaces 52a, 54a.

The piston 12a can be driven by an electric motor lOOa via a striking mechanism transmission 22a, comprising cylindrical gear teeth only, and via an eccentric drive 20a. The eccentric drive 20a is positioned on one side only and an eccentric pin 46a is indeed in its longitudinal direction held only on a side facing the electric motor lOOa via a cylindrical gear 48a and via a bearing spindle 50a coupled to the cylindrical gear 48a.

The hand machine tool striking mechanism unit has according to the invention a striking mechanism parameter Sa, formed by the maximum beater unit surface measurement 16a power three divided by the beater unit mass 18a, of approximately 500 mrri/g. The beater unit surface measurement 16a is here formed by a diameter of a cylindrically constructed beater basic body 30a or advantageously by a diameter of the operating surface 52a of the beater unit l0a.

In operation the hand machine tool is pressed by an operator with a tool 56a against an object to be machined.

The tool 56a, a striking pin 58a and the beater unit lOa are thereby displaced out of their idle positions in the direction of the piston 12a into their striking positions, whereby control apertures 24a in the guide means 32a are closed by the beater basic body 30a, so a pressure required for driving the beater unit lOa can build up in the gas volume l4a between the piston 12a and the beater unit lOa.

The control apertures 24a are directly coupled by fluid technics to a machinery space 26a formed by a lubricating oil space, as indicated schematically by a channel 62a. The machinery space 26a is connected solely via pressure equalising channels, not illustrated in greater detail, to an environment of the hand machine tool, so a direct gas exchange between the gas volume l4a and the environment of the hand machine tool is avoided.

The hand machine tool striking mechanism unit is illustrated in a socalled striking position, in which the beater unit lOa impacts straight on to the striking pin 58a and the piston l2a is in its front end position facing the beater unit lOa. An axial distance 64a between the operating surfaces 52a, 54a of the beater unit lOa and the piston 12a in the striking position corresponds to approximately the beater unit surface measurement l6a or in particular to the diameter of the operating surface 52a of the beater unit lOa. In operation a maximum gas pressure of approximately 4 to 5 bar builds up inside the gas volume 14a.

In Figs. 2 to 11 details of alternative hand machine tool striking mechanism units are illustrated. Components which remain substantially identical are basically numbered with the same reference numerals, the letters a to k being added to the reference numerals to distinguish between the embodiment examples. Reference can further be made in respect of features and functions which remain the same to the description of the embodiment example in Fig. 1 or in each case to the previously described embodiment examples.

The following description is substantially confined to the differences from the embodiment example in Fig. 1 or from the previously described embodiment examples.

The hand machine tool beater unit in Fig. 2 has a beater unit lOb, comprising a cylindrical beater basic body 30b and two annular decoupling means 28b, 28b', which is provided for dimensional decoupling of an outer dimension of the beater basic body 30b from a guide means 32b of the beater unit lOb formed by a hammer tube. The decoupling means 28b here advantageously forms part of an operating surface 52b of the beater unit lOb, pointing towards the piston 12b or interacting with a gas volume l4b. It would basically also be conceivable for a decoupling means to form completely an operating surface of a beater unit interacting with a gas volume.

The beater unit lOb comprises couplings 34b, 34b' between the decoupling means 28b, 28b' and the beater basic body 30b, provided to couple the beater basic body 30b and the decoupling means 28b, 28b' during a flight phase of the beater basic body 30b or of the beater unit lOb at least largely synchronously, i.e. apart from a vibration- absorbing relative movement. The couplings 34b, 34b' are constructed as vibration-absorbing and comprise connections produced by vulcanising on or the decoupling means 28b, 28b' are vulcanised on to the beater basic body 30b.

The beater basic body 30b is made of steel, while the decoupling means 28b, 28b' are made of a lighter material than steel, in fact of plastics material.

The decoupling means 28b, 28b' in each case form a guide surface 36b, 38b, via which the beater unit lOb is guided inside the tubular guide means 32b formed by the hammer tube, the guide surface 38b of the decoupling means 28b being interrupted by a groove 66b for a sealing ring 68b.

The hand machine tool striking mechanism unit in Fig. 2 has according to the invention a striking mechanism parameter Sb, formed by the maximum beater unit surface measurement l6b power three divided by the beater unit mass l8b, of approximately 500 mm3/g. The beater unit mass 18b is composed in particular of the masses of the decoupling means 28b, 28b' and the beater basic body 30b.

The beater unit surface measurement 16b is advantageously formed by a diameter of the operating surface 52b of the beater unit lOb.

The hand machine tool striking mechanism unit further comprises a striking pin unit 58b, comprising a striking pin basic body 58b' and an annular decoupling means 60b, via which the striking pin unit 58b is guided in the guide means 32b formed by the hammer tube. The decoupling means 60b is in this case made of a lighter material than the striking pin basic body 58b' itself, in fact of a plastics material, while the striking pin basic body 58b' is made of steel. The decoupling means 60b and the striking pin basic body 58b' are coupled in the axial direction by positive locking via a clamping ring 70b, which engages with play in a groove 72b of the decoupling means 60b and in a groove 74b of the striking pin basic body 58b' The hand machine tool striking mechanism unit in Fig. 3 has a beater unit lOc, comprising a substantially cylindrical beater basic body 30c and a substantially annular decoupling means 28c, provided for dimensional decoupling of an outer dimension of the beater basic body 30c from a guide means 32c of the beater unit lOc formed by a pot piston 12c. The decoupling means 28c advantageously forms part of an operating surface 52c of the beater unit lOc pointing towards an operating surface 54c of the pot piston 12c or interacting with a gas volume 14c.

The beater unit lOc comprises a coupling 34c between the decoupling means 28c and the beater basic body 30c, provided to couple the beater basic body 30c and the decoupling means 28c during a flight phase of the beater basic body 30c or the beater unit 30c at least largely synchronously. The coupling 34c is constructed as vibration-absorbing, the decoupling means 28c and the beater basic body 30c in fact being coupled via annular absorbing elements 76c, 78c made of rubber, via a clamping ring 80c, a contact washer 82c and via an extension 84c moulded on to the decoupling means 28c via a positive locking connection specifically allowing a limited relative movement.

The decoupling means 28c form two guide surfaces 36c, 38c spaced apart in the axial direction, via which the beater unit lOc is guided inside the guide means 32c formed by the pot piston 12c, guide surface 38c being interrupted by a groove 66c for a sealing ring 68c. The pot piston 12c is guided in a hammer tube 86c.

In Figs. 4 and 5 are illustrated hand machine tool striking mechanism units with beater units lOd, lOe, constructed as stepped, or with beater units lOd, lOe having differing guide diameters 88d, 88e, 90d, 90e, guide diameters 90d, 90e coinciding in each case with the maximum beater unit surface measurements 16d, 16e. The beater unit lOd has a stepped beater basic body 30d, which has two cylindrical basic shapes with differing diameters and which is guided in the area of its smaller diameter on a side facing away from a piston l2d via a decoupling means 28d in a guide means 32d formed by a hammer tube.

Beater unit lOe has a cylindrical beater basic body 30e with a constant diameter 88e, which is guided on its side facing a piston 12e via a decoupling means 28e in a guide means 32e formed by a hammer tube. The decoupling means 28e here forms part of an operating surface 52e of the beater unit l0e interacting with a gas volume 14e. On its side facing away from the piston 12e the beater basic body 30e is guided directly in the guide means 32e.

The hand machine tool striking mechanism unit in Fig. 6 comprises a beater unit lOf with a beater basic body 30f and a decoupling means 28f, provided for dimensional decoupling of the beater basic body 30f. The decoupling means 28f is provided to form jointly with the beater basic body 30f a groove 66f for a sealing ring 68f. Because of the decoupling means 28f the beater basic body 30f can be constructed with thin walls in the axial direction in the area of its guide surface 92f and yet the sealing ring 68f can advantageously be arranged in this area. The decoupling means 28f is arranged starting from a piston 12f in the direction of a tool, not illustrated in greater detail, after the guide surface 92f of the beater unit lOf or of the beater basic body 30f facing the piston 12f.

However, it is also conceivable that a decoupling means 28g is arranged starting from a piston 12g in the direction of a tool, not illustrated in greater detail, before a guide surface 92g of a beater basic body 30g facing the piston 12g, as illustrated in Fig. 7. By contrast to the embodiment example in Fig. 6, a groove 66g is formed solely by the decoupling means 28g.

The hand machine tool striking mechanism unit illustrated in Fig 8 has a beater unit l0h with a stepped beater basic body 30h without decoupling means. The beater unit lOh has a parameter, formed by a theoretical diameter 94h in an unstepped cylindrical configuration with the same mass divided by a maximum beater unit surface measurement 16h, of approximately 0.5 and a parameter, formed by a length 96h of the beater unit lOh divided by the maximum beater unit surface measurement 16h, of approximately 1.5.

The maximum beater unit surface measurement l6h corresponds to a diameter of an operating surface 52h of the beater unit lOh interacting with a gas volume 14h.

The hand machine tool striking mechanism unit illustrated in Figs. 9 and 10 has a beater unit lOi with three guide ribs 40 , 42 , 44i, distributed evenly over the circumference. The guide ribs 40 , 42i, 44i are moulded on to a beater basic body 30 in one piece.

The hand machine tool striking mechanism unit in Fig. 11 has a pot-shaped beater unit l0j or a pot-shaped beater basic body 30j, wherein a pot aperture points in the direction of a striking pin 58j. In an illustrated striking position the striking pin 58j projects into the pot-shaped beater unit lOj and comes into contact with a side of a pot floor of the beater unit lOj facing the pot aperture.

The hand machine tool striking mechanism unit in Fig. 12 has a double-pot-shaped or H-shaped in diameter beater unit 10k or a double-pot-shaped beater basic body 30k, wherein one pot aperture points in the direction of a piston 12k and one pot aperture in the direction of a striking pin 58k. In an illustrated striking positioN an extension 98k of the piston 12k pointing in the axial direction projects into the pot-shaped beater unit 10k and the striking pin 58k projects into the pot-shaped beater unit 10k and comes into contact with a side of a pot floor of the beater unit 10k facing it. It is basically also conceivable that a striking pin is provided which has only one pot aperture in the direction of a piston.

Reference numerals beater unit 12 piston 14 gas volume 16 beater unit surface measurement 18 beater unit mass eccentric drive 22 strikingmechanism transmission 24 control aperture 26 machinery space 28 decoupling means beater basic body 32 guide means 34 coupling 36 guide surface 38 guide surface guide rib 42 guide rib 44 guide rib 46 eccentric pin 48 cylindrical gear bearing spindle 52 operating surface 54 operating surface 56 tool 58 striking pin unit decoupling means 62 channel 64 distance 66 groove 68 sealing ring clamping ring 72 groove 74 groove 76 absorbing element 78 absorbing element 80 clamping ring 82 contact washer 84 extension 86 hammer tube 88 guide diameter 90 guide diameter 92 guide surface 94 dJameter 96 length 98 extension 100 electric motor S striking mechanism parameter

Claims

Claims 1. Hand machine tool striking mechanism unit with a beater unit

(lOa - 10k) which can be driven by means of a piston (l2a - 12k) via a gas volume (14a - 14k), characterised in that a striking mechanism parameter (Sa - Sk), formed by the maximum beater unit surface measurement (16a 16k) power three divided by the beater unit mass (18a - 18k), is greater than 200 mm3/g, preferably greater than 220 mm3/g and particularly preferably greater than 240 rnm3/g.

2. Hand machine tool striking mechanism unit according to claim 1, characterised in that the striking mechanism parameter (Sa - Sk) is greater than 280 rnm3/g, preferably greater than 320 mm3/g and particularly preferably greater than 380 mm3/g.

3. Hand machine tool striking mechanism unit according to claim 1 or 2, characterised in that the striking mechanism parameter (Sa - Sk) is smaller than 2000 mrn3/g.

4. Hand machine tool striking mechanism unit according to the preamble of patent claim 1 and in particular according to one of the preceding claims, characterised in that in operation a maximum gas pressure in the gas volume (l4a - 14k) is less than 10 bar, advantageously less than 8 bar and particularly advantageously less than 6 bar.

5. Hand machine tool striking mechanism unit according to one of the preceding claims, characterised by an eccentric drive (20a) positioned on one side.

6. Hand machine tool striking mechanism unit according to one of the preceding claims, characterised by a striking mechanism transmission (22a) with cylindrical gear teeth only.

7. Hand machine tool striking mechanism unit according to one of the preceding claims, characterised by at least one control aperture (24a), provided for controlling the gas volume (l4a) and coupled to a machinery space (26a) 8. Hand machine tool striking mechanism unit according to one of the preceding claims, characterised in that the beater unit (lOb - lOg) comprises at least one decoupling means (28b - 28g), provided for dimensional decoupling of a beater basic body (30b - 30g) of the beater unit (lOb - lOg) and with a coupling (34b - 34g) between the decoupling means (28b - 28g) and the beater basic body (30b - 30g), provided for coupling the beater basic body (30b - 30g) and the decoupling means (28b 28g) during a flight phase of the beater basic body (30b - 30g) at least largely synchronously.

9. Hand machine tool striking mechanism unit according to claim 8, characterised in that the decoupling means (28b - 28g) is provided for at least partial decoupling of an outer dimension of the beater basic body (30b - 30e) from a guide means (32b - 32e) of the beater unit (lOb - lOe) 10. Hand machine tool striking mechanism unit according to claim 8 or 9, characterised in that the decoupling means (28b - 28g) is made of a lighter material than the beater basic body (30b - 30g) 11. Hand machine tool striking mechanism unit at least according to claim 9, characterised in that the coupling (34b - 34e) and/or the decoupling means (28b - 28e) is constructed as at least partially vibration- absorbing.

12. Hand machine tool striking mechanism unit according to claim 11, characterised in that the coupling (34b) comprises at least one connection produced by vulcanising on.

13. Hand machine tool striking mechanism unit at least according to claim 8, characterised in that the decoupling means (28b - 28e) has at least one guide surface (36b - 36e, 38b - 38e) lU. Hand machine tool striking mechanism unit according to claim 13, characterised in that the decoupling means (28c) has at least two guide surfaces (36b, 38b) spaced apart in the axial direction.

15. Hand machine tool striking mechanism unit according to one of the preceding claims, characterised in that the beater unit (101) has at least one guide rib (4Oi, 42i) 16. Hand machine tool striking mechanism unit according to one of the preceding claims, characterised in thaL the beater unit (lOd, lOe, lOh) is constructed as stepped.

17. A hand machine tool striking mechanism substantially as herein described with reference to the accompanying drawings.

18. Hand machine tool with a hand machine tool striking mechanism unit according to one of the preceding claims.