EP2176036B1 - Hand-held power tool comprising a spring unit - Google Patents

Description

State of the art

The invention relates to a hand tool according to the preamble of claim 1.

From the DE 100 66 115 A1 is a generic hand tool known. The hand tool has a drive unit arranged in a housing, with which a tool holder can be driven in a hammering manner. A part of the housing is designed as an actuating handle. In addition, the hand tool machine has a second handle, which is designed in particular for guiding or holding oscillating devices, in that the handle has a vibration damping device. For this purpose, the handle on a handle element, in which the damping device is integrated.

From the FR 446 414 A and the JP 2003 245871 A Hand tool machines are known according to the preamble of claim 1.

Advantages of the invention

The invention is based on a hand-held power tool, in particular a drill and / or chisel hammer, with a drive unit and a percussion unit, which has a gear unit and a piston that can be driven bidirectionally displaceably by the drive unit, and with at least one first gear unit in the direction of action the drive unit between the drive unit and the piston provided spring unit.

According to the invention, the transmission unit is an eccentric drive with a two-part eccentric disk, the eccentric disk having a drive disk and an output disk coupled to the drive disk via the at least one first spring unit. As a result, the vibration damping is particularly space-saving and cost-effectively integrated into the eccentric disc. In addition, the eccentric disc is carried out particularly stable by the two-part design and the integration of the spring units. Advantageously, spring units are provided which have either one effective direction or two effective directions. The fact that the at least one first spring unit can be integrated into an existing construction, this has no effect on the overall length of the power tool or on the gear unit of the power tool. The vibration damping takes place here advantageously without the expenditure of additional energy. The vibration damping system according to the invention responds directly to the compression pressure, so that the system is independent of the mode and the load on the transmission of the power tool.

The drive unit acts on the piston via the gear unit with a drive force and is preferably designed as an electric motor. The term "spring unit" should be understood as meaning, in particular, mechanical, hydraulic and / or pneumatic springs as well as gas cushions as well as all spring devices which appear appropriate to a person skilled in the art. The term "effective direction of the drive unit" should be understood to mean, in particular, the direction of the force flow of the drive force on the piston. In particular, two movable parts designed as pistons and beaters, which are accommodated axially behind one another in a separate guide tube fixed relative to the moving parts and are guided axially, bidirectionally displaceably, are to be understood here as "beater units", the beater in a known manner can be activated via the piston, which can be moved by the drive, via an air cushion. A "gear unit" is to be understood in particular as meaning a unit for transmitting the driving force of the drive unit and / or for converting the driving force present as rotational or rotational movement into a linear or lifting movement. It can be used all, the expert appear appropriate gear arrangements.

In the present embodiments, the gear unit is formed by the following elements, namely the part of the motor shaft from an upper edge of the Electric motor and the transmission of the driving force from the electric motor to the piston of the percussion unit drivingly coupled, further transmission means, such as a connecting rod. If a gear means, as in the present exemplary embodiments, is formed by a motor shaft, which is expressly also to be regarded as part of the gear unit, in particular the drive unit can be made particularly space-saving. Furthermore, a center of gravity of the drive unit can advantageously be adjusted in its position to marginal conditions. In this case, a "motor shaft" should be understood to mean, in particular, a shaft which can be driven directly by means of a turbine unit and / or by means of an electromagnetic unit of the drive unit. Such a design allows a reduction of vibrations of the striking hand tool. About the drive unit, the piston is offset from a starting position in a reciprocating, axial stroke movement in the guide tube, wherein an air cushion is alternately compressed and relaxed in a compression chamber. The racket is accelerated by the compression pressure and gives its energy in the form of a punching power to a tool.

The eccentric drive has an eccentric pin, a connecting rod and a piston pin, wherein a further spring unit between the eccentric pin and the connecting rod or between the connecting rod and the piston pin or in the connecting rod or between the piston pin and the piston is provided. These embodiments make it possible to integrate the spring unit into a common gear unit, in that only one component or a few components have to be adapted.

Furthermore, it is proposed that the at least one first spring unit is a mechanical, hydraulic and / or pneumatic spring and / or a gas cushion. The free choice of different types of springs allows for accurate tuning of the damping system. About the nature of the at least one spring unit both spring force and travel are selectable or adjustable.

It is also proposed that the at least one first spring unit is a compression spring, as a result of which the gear unit or the damping system can be produced in a structurally simple and particularly cost-effective manner.

In addition, it is proposed that the at least one first spring unit is an element made of an elastic material. This is a special cost-effective solution possible, since a simple production of the spring element is feasible.

drawing

Further advantages emerge from the following description of the drawing. In the drawings, several embodiments of the invention are illustrated. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Fig. 1

eine Prinzipskizze eines Teils einer Handwerkzeugmaschine gemäß einer gegenüber den Figuren 6 bis 8 weiteren Ausführungsform in einer Draufsicht mit einem Exzenterantrieb und einem Teilschnitt durch eine Schlagwerkeinheit, wobei eine Federeinheit zwischen der Antriebseinheit und einem Kolben der Schlagwerkeinheit angeordnet ist,

Fig. 2

eine Prinzipskizze der Handwerkzeugmaschine gemäß Fig. 1 in einer Seitenansicht, wobei die Federeinheit zwischen einem Exzenterbolzen des Exzenterantriebs und einem Pleuel der Schlagwerkeinheit angeordnet ist,

Fig. 3

die Handwerkzeugmaschine in einer weiteren Ausführungsform mit einem Exzenterantrieb, wobei die Federeinheit zwischen dem Pleuel und dem Kolbenbolzen vorgesehen ist,

Fig. 4

die Handwerkzeugmaschine in einer gegenüber den Figuren 6 bis 8 weiteren Ausführungsform mit einem Exzenterantrieb, wobei die Federeinheit am Pleuel vorgesehen ist,

Fig. 5

die Handwerkzeugmaschine in einer gegenüber den Figuren 6 bis 8 weiteren Ausführungsform mit einem Exzenterantrieb, wobei die Federeinheit zwischen dem Kolbenbolzen und dem Kolben vorgesehen ist,

Fig. 6

die erfindungsgemäße Handwerkzeugmaschine mit einem Exzenterantrieb, der eine Exzenterscheibe mit einer Antriebsscheibe und einer mit der Antriebsscheibe gekoppelte Abtriebsscheibe aufweist, wobei die Antriebsscheibe über die Federeinheit mit der Abtriebsscheibe gekoppelt ist,

Fig. 7

die Exzenterscheibe aus Fig. 6, bei welcher die Federeinheit eine Wirkrichtung aufweist,

Fig. 8

die Exzenterscheibe aus Fig. 6, bei welcher die Federeinheit zwei Wirkrichtungen aufweist,

Fig. 9

eine Federeinheit aus elastischem Material,

Fig. 10

eine Federeinheit mit zwei Druckfedern,

Show it:

Fig. 1

a schematic diagram of a part of a hand tool according to one of the FIGS. 6 to 8 another embodiment in a plan view with an eccentric drive and a partial section through a percussion unit, wherein a spring unit between the drive unit and a piston of the percussion unit is arranged,

Fig. 2

a schematic diagram of the power tool according to Fig. 1 in a side view, wherein the spring unit is arranged between an eccentric pin of the eccentric drive and a connecting rod of the percussion mechanism unit,

Fig. 3

the hand tool in a further embodiment with an eccentric drive, wherein the spring unit is provided between the connecting rod and the piston pin,

Fig. 4

the hand tool in one opposite the FIGS. 6 to 8 another embodiment with an eccentric drive, wherein the spring unit is provided on the connecting rod,

Fig. 5

the hand tool in one opposite the FIGS. 6 to 8 another embodiment with an eccentric drive, wherein the spring unit is provided between the piston pin and the piston,

Fig. 6

the hand tool according to the invention with an eccentric drive having an eccentric disc with a drive pulley and a driven pulley coupled to the drive pulley, wherein the drive pulley is coupled via the spring unit with the driven pulley,

Fig. 7

the eccentric disc Fig. 6 in which the spring unit has a direction of action,

Fig. 8

the eccentric disc Fig. 6 in which the spring unit has two directions of action,

Fig. 9

a spring unit made of elastic material,

Fig. 10

a spring unit with two compression springs,

Description of the embodiments

The figures show schematic diagrams of part of a trained as an electric hammer hand tool. The electric hammer has a arranged in a housing 48, in Fig. 1 visible drive unit 10 and a percussion unit 12. The drive unit 10 is preferably designed as an electric motor. The drive unit 10 acts via a gear unit 14a on the hammer mechanism unit 12, wherein the gear unit 14a is designed as an eccentric drive.

The percussion unit 12 comprises two formed as a piston 18 and racket 20 movable parts, which are received in a separate, fixed relative to the moving parts guide 16 axially one behind the other and axially, bidirectionally slidably guided. The guide 16 is preferably formed as a tube. The drive unit 10 drives the piston 18, which is displaceably arranged in the guide tube 16, via the gear unit 14a.

A first end face of the piston 18 and a first end face of the racket 20, which face each other, define a compression space 50 in which an air cushion is enclosed. An axis of the guide tube 16 is aligned with the axis of a tool holder, not shown, in which a tool is receivable. A transmitted from the engine 10 to the gear unit 14a rotational movement is converted into a linear lifting movement of a connecting rod 26a-26g and transmitted via the piston 18 to the racket 20.

In a backward movement of the piston 18 creates a negative pressure, which pulls the racket 20 to the rear. During a forward movement of the piston 18 creates an overpressure between the piston 18 and racket 20, which accelerates the racket 20 forward. The forward flying bat 20 hits a striker, not shown here and gives off its kinetic energy. The pulse of the racket 20 is transmitted from the firing pin on the tool (drill or chisel) also not shown here.

Thus, the piston 18 via the drive unit 10 from an example in Fig. 1 shown starting position in a reciprocating, axial stroke movement in the guide tube 16, wherein the air cushion in the compression chamber 50 is alternately compressed and relaxed. The racket 20 is accelerated by the compression pressure and gives its energy to the tool.

The gear unit 14a is designed as an eccentric drive and comprises a motor shaft 52, an eccentric disc 30a, 30b with an eccentric pin 24 and a connecting rod 26a-26g with a piston pin 28. The eccentric disc 30a, 30b is driven by the motor 10 via the gear unit 14a. The eccentric disc 30a, 30b is mounted via an eccentric shaft 54 in the housing 48 of the power tool. To drive the motor shaft 52 via a pinion 58 with the eccentric disc 30a, 30b into engagement. The eccentric disc 30a, 30b is connected via the eccentric pin 24 with the connecting rod 26a-26g. The connecting rod 26a-26g is connected by the piston pin 28 with the piston 18 of the percussion unit 12, which is operatively connected to the racket 20 and acts on the racket 20.

Fig. 6 shows the hand tool according to the invention with a designed as an eccentric 14a gear unit having a two-part eccentric disc 30a, namely a drive pulley 32a, 32b and a drive pulley 32a, 32b coupled to the output pulley 34, the drive pulley 32a, 32b via the first spring unit 22b, 22c is coupled to the driven pulley 34. Here, the motor shaft 52 drives the drive pulley 32a, 32b, which drives the driven pulley 34 via the spring units 22b, 22c. As a result, the force peaks caused by the compression pressure are also reduced. Fig. 7 shows the eccentric disc 30a Fig. 6 in a first variant. In this case, two spring units 22b are provided between the drive pulley 32a and the driven pulley 34, which can effect the force reduction only in one effective direction or rotational direction 36. Fig. 8 shows the eccentric disc 30a Fig. 6 in a second variant. In this case, two spring units 22c are again provided between the drive pulley 32b and the driven pulley 34, which, however, can effect a force reduction in two directions of action or directions of rotation 36, 38.

In order to improve in particular the vibration behavior of the power tool or to reduce the vibration of the power tool, according to the invention at least the first spring unit 22b, 22c, and optionally at least one further spring unit 22a, 22d, 22f, in the effective direction of the drive unit 10 between the drive unit 10 and the Piston 18 provided in the transmission unit 14a.

In one opposite the FIGS. 6 to 8 another embodiment according to the Figures 1 and 2 the further spring unit 22a is provided between the eccentric pin 24 and the connecting rod 26a.

Alternatively, in a second embodiment according to Fig. 3 the further spring unit 22a may be provided between the connecting rod 26b and the piston pin 28.

In a further embodiment according to Fig. 4 is the other spring unit 22a provided on or in the connecting rod 26c by the connecting rod 26c made in two parts and the spring unit 22a is provided between the two parts. As a result, the two parts of the connecting rod 26c can be moved against each other.

Furthermore, the further spring unit 22a according to FIG Fig. 5 be arranged between the piston pin 28 and the piston 18, in such a way that the piston pin 28 is slidably mounted in the piston 18.

The at least one first spring unit 22b, 22c and in the other spring unit 22a, 22d, 22f, it may be at least one mechanical, hydraulic and / or pneumatic spring and / or a gas cushion. Preferably, the spring unit 22a-22e is designed as a compression spring. Alternatively, it may according to Fig. 9 but also an element 22d of a resilient material or according to Fig. 10 to act an element 22e with two opposing spring elements.

Claims (9)

1. Portable power tool, in particular rotary and/or demolition hammer, having a drive unit (10) and a percussion mechanism unit (12) which has a transmission unit (14a) and a piston (18) that is drivable by the drive unit (10) and is arranged in a bidirectionally displaceable manner, and also having at least one first spring unit (22b, 22c) that is provided in the transmission unit (14a) between the drive unit (10) and the piston (18) in the effective direction of the drive unit (10), characterized in that the transmission unit (14a) is an eccentric drive having a two-part eccentric disc (30a), wherein the eccentric disc (30a) has a drive input disc (32a, 32b) and a drive output disc (34) coupled to the drive input disc (32a, 32b) via the at least one first spring unit (22b, 22c).
2. Portable power tool according to Claim 1, characterized in that the eccentric drive has an eccentric pin (24), a connecting rod (26a-26g) and a piston pin (28).
3. Portable power tool according to Claim 2, characterized in that a further spring unit (22a, 22d, 22e) is provided between the eccentric pin (24) and the connecting rod (26a, 26f, 26g) of the eccentric drive.
4. Portable power tool according to Claim 2, characterized in that a further spring unit (22a) is provided between the connecting rod (26b) and the piston pin (28) of the eccentric drive.
5. Portable power tool according to Claim 2, characterized in that a further spring unit (22a) is provided in the connecting rod (26c) of the eccentric drive.
6. Portable power tool according to Claim 2, characterized in that a further spring unit (22a) is provided between the piston pin (28) of the eccentric drive and the piston (18).
7. Portable power tool according to one of the preceding claims, characterized in that the at least one first spring unit (22b, 22c) and the further spring unit (22a, 22d, 22f) are mechanical, hydraulic and/or pneumatic springs and/or gas cushions.
8. Portable power tool according to one of the preceding Claims 1 to 7, characterized in that the at least one first spring unit (22b, 22c) and the further spring unit (22a, 22d, 22f) are configured as compression springs.
9. Portable power tool according to one of the preceding Claims 1 to 7, characterized in that the at least one first spring unit (22b, 22c) and the further spring unit (22a, 22d, 22f) have an element made of a resiliently elastic material.

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