The present invention relates to a hammer drill and/or chipping hammer having a drive motor, an impact mechanism and a tool fitting for fitting a tool. The impact mechanism has an anvil that is axially displaceable in an anvil guide and acts on the tool. The impact mechanism is equipped with an idle-strike damper element and a rebound-strike damper element.
Hammer drills of the type mentioned at the beginning are known in principle from the prior art.
Idle-strike damper elements and rebound-strike damper elements, which are preferably in the form of elastomer damping elements, are used in order to keep force peaks on downstream components and vibrations as low as possible. When the impact mechanism is at the working point, the anvil butts, after each strike, against a typically provided rebound-strike disk and this is absorbed by the rebound-strike damping element.
In the event of too low a pressing force or the breaking away of concrete/stone to be worked on, idle strikes can occur. This means that strikes with full impact energy have to be absorbed by the hammer and in particular the tool fitting itself. In order to protect the downstream components from a force peak of the idle strike, use is typically made of an idle-strike damping element. Idle-strike damping by the idle-strike damper element influences the return speed of the anvil after an idle strike and thus also the deactivation behavior of the hammer.
It is an object of the present invention to provide a hammer drill and/or chipping hammer in which the impact mechanism has a comparatively simple structure and as a result is comparatively cost-effective.
The present invention provides that the idle-strike damper element and/or the rebound-strike damper element is/are integrated on the anvil. This has the advantage that the anvil together with the idle-strike damper element and/or rebound-strike damper element can be mounted in one working step—and thus in a comparatively inexpensive manner. This also results in an advantageous reduction in components to be kept available, leading in a related manner to a cost reduction.
In a particularly preferred embodiment, the idle-strike damper element and the rebound-strike damper element are formed in one piece with one another as a combined damper element. Thus, idle-strike damping and rebound-strike damping can take place by way of one and the same component. It has been found to be advantageous if the combined damper element is in the form of an elastomer. In a particularly preferred embodiment, the combined damper element has been vulcanized on the anvil. Alternatively or in addition, the combined damper element can be connected to the anvil by a form-fitting connection.
It has been found to be advantageous if the combined damper element is surrounded by a stop sleeve, which is arranged so as to strike an idle-strike stop surface on one side and to strike a rebound-strike stop surface on the other side. The stop sleeve can be spaced apart in a radial direction from the anvil, wherein the elastomer is located preferably in a radial direction between the anvil and stop sleeve.
In a particularly preferred embodiment, the idle-strike stop surface is formed on the tool fitting itself. The rebound-strike stop surface can advantageously be formed on a stop ring comprised by the tool fitting. Alternatively, it is possible to dispense with a stop ring on the rebound-strike side, and the rebound-strike stop surface can be formed directly on the tool fitting.
In a particularly preferred embodiment, the stop ring is supported by an auxiliary rebound-strike damper element with respect to the tool fitting.
It has been found to be advantageous if the impact mechanism has a guide housing, which engages at least partially around the anvil and/or the tool fitting. In a particularly preferred embodiment, the tool fitting is movable in the axial direction relative to the guide housing and/or is arranged at least partially within the guide housing. In a further particularly preferred embodiment, the impact mechanism has an additional idle-strike damper element, which acts preferably between the tool fitting and the guide housing. The impact mechanism may have an additional rebound-strike damper element, which acts preferably between the tool fitting and the guide housing. Force introduction from the tool fitting into the unit made up of the additional idle-strike damper element and additional rebound-strike damper element can take place by way of a peg protruding in a radial direction from the tool fitting. In a particularly preferred embodiment, the peg engages, with respect to the axial direction of the anvil, between the additional idle-strike damper element and additional rebound-strike damper element.
As a result of cooperation of the additional idle-strike damper element and additional rebound-strike damper element, it is possible for the tool fitting to be mounted in a floating manner, with the result that a not inconsiderable part of the impact energy of the anvil can already be attenuated.
Further advantages will become apparent from the following description of the figures. Various exemplary embodiments of the present invention are shown in the figures. The figures, the description and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them to form useful further combinations.
In the figures, identical and similar components are denoted by the same reference signs. In the figures:
A preferred exemplary embodiment of a hammer drill and/or chipping hammer 100 according to the invention is illustrated in
The impact mechanism 10 has an anvil 30 that is displaceable in the axial direction AR in an anvil guide 20 and acts on the tool 110. The anvil guide 20 is realized for example by two rolling bearings 21, 23, which are respectively supported both in a radial direction RR and in the axial direction AR against the tool fitting 50.
The impact mechanism 10 is equipped with an idle-strike damper element 11 and a rebound-strike damper element 13, which are integrated according to the invention on the anvil 30. As is apparent from
As is likewise apparent from
A preferred exemplary embodiment of an impact mechanism 10 is illustrated in
In contrast to the exemplary embodiment shown in
Number | Date | Country | Kind |
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19209441.5 | Nov 2019 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/081266 | 11/6/2020 | WO |