Patent Grant
12172279
The invention relates to a power tool, in particular a hammer drill, comprising a housing, a tool fitting for receiving and holding a tool, an impact device for producing and transmitting impact pulses to the tool, and a rotation device for producing and transmitting a torque to the tool, wherein a working axis passing through the impact device is provided.
Various power tools in the form of hammer drills are known from the prior art. A hammer drill is a machine for drilling holes in mineral materials such as rock or concrete. Among the components of the hammer drill are a rotary drive and an impact mechanism. By means of the rotary drive, a drilling tool held by the hammer drill is rotated about an axis of rotation (also referred to as the working axis). The impact mechanism serves to produce impact pulses on the drilling tool along the working or impact axis. By means of the impact pulses, the cutting edge of the drilling tool breaks down the material to be worked. Usually, these hammer drills known from the prior art have just one electric motor as a drive, which drives both the rotary drive and the impact mechanism via a relatively complex transmission.
However, these prior-art power tools configured as hammer drills often have the problem that the transmission for distributing the torque produced by the drive to the rotary drive and the impact mechanism is of excessively complex design. Complex means that a high number of mechanical components are required for the construction and operation of the transmission. Owing to the complexity, a transmission of this kind may be expensive to manufacture, produce and maintain. Moreover, transmissions of such complex design have a relatively high susceptibility to malfunctions or even complete failure.
It is therefore an object of the present invention to make available a power tool, in particular a hammer drill, to solve the abovementioned problem.
The present invention provides a power tool, in particular a hammer drill, comprising a housing, a tool fitting for receiving and holding a tool, an impact device for producing and transmitting impact pulses to the tool, and a rotation device for producing and transmitting a torque to the tool, wherein a working axis passing through the impact device is provided.
According to the invention, the power tool comprises a first drive unit having a first axis of rotation for driving the rotation device and a second drive unit having a second axis of rotation for driving the impact device, wherein the first and second drive units are arranged in such a way relative to one another in the housing that the first axis of rotation of the first drive unit is arranged at a first angle to the second axis of rotation of the second drive unit and at a second angle to the working axis.
As a result, it is possible to dispense with a single complex transmission and to make the power tool significantly simpler and more robust overall.
According to an advantageous exemplary embodiment, both the first angle and the second angle may be configured as acute angles, wherein the first angle can have a value of 50° to 80°, and the second angle can have a value of 10° to 30°.
As a result, the installation space within the housing can be used in a particularly effective way, and the power tool can be of compact configuration overall.
According to another advantageous exemplary embodiment, the first drive unit may comprise a first transmission device and the second drive unit may comprise a second transmission device.
This is a simple way of implementing an independent or separate transmission ratio from the first drive unit to the rotation device and from the second drive unit to the impact device.
According to an advantageous exemplary embodiment, the power tool may comprise a gearwheel in the form of a bevel gear for connecting the first drive unit to the rotation device.
It is thereby possible to achieve virtually optimum connection of the first drive unit to the rotation device.
Further advantages will become apparent from the following description of the figures.
Various exemplary embodiments of the present invention are illustrated in the figures.
The figures, the description and the patent claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them to produce useful further combinations.
In the figures, identical and similar components and assemblies are denoted by the same reference signs.
Specifically:
The power tool 1, which is configured as a hammer drill, has a housing 2, a tool fitting 3 and a power supply unit 4.
The housing substantially comprises a front end 2a, a rear end 2b, a left-hand side, a right-hand side, an upper side and a lower side.
As can be seen in
The user is not illustrated in the figures.
In this case, the first handle 5 comprises an activation switch 5a for activating the power tool 1. The activation switch 5a is connected to a control unit 6 and via leads L in such a way that the power tool 1 is transferred from a deactivation mode to an activation mode when the activation switch 5a is moved in arrow direction B. Conversely, the power tool 1 is transferred from the activation mode to the deactivation mode when the activation switch 5a is moved in arrow direction A by means of a spring. The control unit 6, for its part, is connected to the power supply unit 4 via leads L for the open-loop and closed-loop control of various functions.
The power supply unit 4 serves to supply electrical energy to the power tool 1. In the exemplary embodiment which is under consideration and is shown in the figures, the power supply unit 4 is in the form of a rechargeable battery (also referred to as a power pack or battery) that can be released from the power tool 1. According to an alternative exemplary embodiment, the power supply unit 4 may also be configured as an electrical cable for releasably connecting the power tool 1 to an electrical grid (that is to say electrical socket).
As is likewise apparent in
Moreover, a second handle 8 is positioned at the front end 2a of the housing 2 of the power tool 1. Together with the first handle 5, the second handle 8 is used for additional holding and guidance of the power tool 1 and may also be referred to as an auxiliary handle. The second handle 8 can be removed from the power tool 1 by means of a connection device 8a.
As can be seen in
As already mentioned above, the control unit 6 serves inter alia to exercise open-loop and closed-loop control over functions of the power supply unit 4. In addition, the control unit 6 performs individual open-loop and closed-loop control over various functions, such as the respective rotational speeds of the first drive unit 11 and the second drive unit 13.
The impact device 9 serves to produce and transmit impact pulses to the tool 7 and, for this purpose, substantially comprises a guide tube 15, an anvil 16 and an exciter piston 17. As illustrated in the figures, the anvil 16 and the exciter piston 17 are positioned inside the guide tube 15. In this arrangement, the anvil 16 is situated ahead of the exciter piston 17 in arrow direction A. The guide tube 15 is connected to the tool fitting 3 for conjoint rotation therewith, and therefore, when the guide tube 15 rotates about the working axis N in direction of rotation R, the tool fitting 3 also rotates about the working axis N in direction of rotation R, as does the tool 7 held in the tool fitting 3.
The rotation device 10 serves to produce and transmit a torque via the guide tube 15 and the tool fitting 3 to the tool 7, which is configured as a drill. For this purpose, the rotation device 10 substantially comprises a gearwheel 18 positioned around the guide tube 15 for conjoint rotation therewith. In the present exemplary embodiment, the gearwheel 18 is configured as a bevel gearwheel. Furthermore, the rotation device 10 comprises a pinion 19 (also referred to as a drive gearwheel) corresponding to the bevel gearwheel 18. As will be described in greater detail below, the pinion 19 is used to drive the gearwheel 18 configured as a bevel gearwheel. The pinion 19 can be positioned either directly on the end 20 of the rotor or on the end 21a of a drive shaft 21 connected to the end 20 of the rotor.
Both the first and the second drive unit 11, 13 are in the form of an electric motor and substantially comprise a stator and a rotor that can be driven around the stator. As can be seen in
The first drive unit 11 configured as an electric motor is connected to the rotation device 10. The second drive unit 13 configured as an electric motor is, in turn, connected to the impact device 9.
According to a first exemplary embodiment, the first drive unit 11 is connected to the rotation device 10 via a drive shaft 21, cf.
The length L of the first drive unit 11, the drive shaft 21 and the pinion 19 is 100 mm. According to alternative exemplary embodiments, the length L may be between 50 and 300 mm and, in particular, between 80 and 200 mm.
According to a second exemplary embodiment, the first drive unit 11 is connected to the rotation device 10 via a first transmission device 12, cf.
The second drive unit 13 is connected to the impact device 9 via a second transmission device 14 in such a way that a torque that can be produced in the first drive unit 11 is transmitted to the exciter piston 17. For this purpose, the second transmission device 14 comprises a pinion 19′, a gearwheel 27, an eccentric 28 and a connecting rod 29. The connecting rod 29 may also be referred to as a con rod, pushrod or main rod.
The pinion 19′ is secured for conjoint rotation on the end 20′ of the rotor of the second drive unit 13, which projects from the stator of the second drive unit 13. The gearwheel 27 of the second transmission device 14 is positioned in such a way relative to the pinion 19′ that the gearwheel 27 is driven by the pinion 19′. The eccentric 28, in turn, is arranged relative to the gearwheel 27 in such a way that the gearwheel 27 drives the eccentric 28. The connecting rod 29 connects the exciter piston 17 to the eccentric 28, with the result that the movement of the eccentric 28 is transmitted to the exciter piston 17. The exciter piston 17 is moved by the eccentric 28 along the guide tube 15 in arrow direction A or B. By means of the movement of the exciter piston 17 in the guide tube 15, the anvil 16 is driven via a pneumatic spring present between the exciter piston 17 and the anvil 16. The anvil 16, in turn, transmits the impact pulses to the tool fitting 3 and the tool 7.
As shown in the figures, the first and second drive units 11, 13 are arranged in such a way relative to one another in the housing 2 that the first axis of rotation S of the first drive unit 11 is arranged at a first angle α to the second axis of rotation T of the second drive unit 13 and at a second angle β to the working axis N. According to the present exemplary embodiment, the value of the first angle α is 60° and the value of the second angle β is 20°. According to alternative embodiments, the first angle α can have a value of 50° to 80°, and the second angle β can have a value between 10° and 30°.
In the present exemplary embodiment, the first axis of rotation S lies in the same plane as the second axis of rotation T. According to an alternative exemplary embodiment, the first axis of rotation S and the second axis of rotation T may also lie in different planes.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20211791 | Dec 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/081831 | 11/16/2021 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2022/117332 | 6/9/2022 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20080314610 | Meixner et al. | Dec 2008 | A1 |
| 20220226951 | Greunke | Jul 2022 | A1 |
| Number | Date | Country |
|---|---|---|
| 106335031 | Jun 2020 | CN |
| 2343661 | Mar 1975 | DE |
| 102005062861 | Jul 2007 | DE |
| 102008054458 | Jun 2010 | DE |
| 0345896 | Dec 1989 | EP |
| 345896 | Sep 1994 | EP |
| 2625931 | Jul 1989 | FR |
| 2625931 | Jul 1989 | FR |
| 2086777 | May 1982 | GB |
| WO 2012084316 | Jun 2012 | WO |
| Entry |
|---|
| International Search Report of PCT/EP2021/081831 dated Jan. 18, 2022. |
| Number | Date | Country | |
|---|---|---|---|
| 20240009822 A1 | Jan 2024 | US |
