This application claims priority under 35 U.S.C. §119 to patent application number DE 10 2015 205 172.2, filed on Mar. 23, 2015 in Germany, the disclosure of which is incorporated herein by reference in its entirety.
The disclosure relates to a power tool, in particular a portable power tool, having a motorized drive unit and having at least one sensor device.
It is already known to integrate sensor devices having corresponding sensors for sensing different operating states into power tools, for example screwdrivers, drills, hammer drills, angle grinders, jigsaws, circular saws, lawnmowers or the like. Thus, DE 103 09 414 A1 discloses a sensor device for sensing a blockage in a portable power tool, in particular in a hammer drill, having at least one motion sensor for sensing a movement variable of the portable power tool in at least two predefined sensitivity axes.
DE 103 32 522 A1 furthermore discloses a portable power tool having a vibration-isolated handle, said portable power tool having an isolation device with passive dampers and with at least one active damping element. A regulator regulates the damping by way of sensor values sensed by a sensor, wherein the sensor is an acceleration sensor for sensing relative acceleration values of the handle of the portable power tool for active acceleration regulation.
DE 10 2012 208 180 A1 shows a handheld reciprocating jigsaw or pendulum action jigsaw having an acceleration sensor which is configured to allow detection of vibrations of the output shaft of a drive motor of the jigsaw in order to detect operating errors.
DE 10 2011 085 565 A1 discloses an autonomous work apparatus, in particular an autonomous lawnmower, having at least one computing unit and at least one collision detection device, which has at least one sensor unit, wherein the sensor unit comprises at least one acceleration sensor.
According to the prior art, the respective sensor devices or units are fastened in or on the housings of the power tools by screws, plugs, clamps or adhesive bonding, in order as a result to establish firm and intimate contact and to achieve determination of the vibratory and acceleration values that is as exact as possible.
However, it has been shown that, as a result of the vibrations of the power tools in operation, relative movements can occur at the bearings of the sensor devices or of the electronic units contained therein, for example between the housing and electronic unit. These relative movements can result for example in misdetection of blockages when the vibrations at the electronic units differ from those of the power tool as a result of play in the bearings. Moreover, wear and abrasion occur as a result of the relative movements, with the result that the play in the bearings is additionally increased and thus the risk of false tripping is further increased. As a result of this increased play, as the service life of the power tool increases, new, undesired contact points can arise between the sensor device or the electronic unit contained therein and the housing of the power tool, and these can result in false tripping.
Therefore, it is the object of the disclosure to reduce or entirely avoid the above-described disadvantages of the prior art.
The disclosure relates to a power tool, in particular a portable power tool, having a housing, having at least one motorized drive unit and having at least one sensor device, wherein the at least one motorized drive unit is mounted in and the at least one sensor device is mounted in or on the housing, and wherein the at least one sensor device has an electronic unit and at least one sensor arranged on the electronic unit. According to the disclosure, provision is made for the housing and/or the sensor device and/or the electronic unit to have at least one bearing for mounting, said bearing containing at least one resilient element for damping or reducing vibrations between the housing and the electronic unit. Advantageously, misdetection of particular, in particular safety-related operating conditions, for example an uncontrollable blockage of a hammer drill or a collision of an autonomous lawnmower, can be reduced considerably or entirely avoided to some extent. In connection with the sensor device of a semiautonomous jigsaw, it is furthermore possible to improve the detection of parameters which are necessary for semiautonomous guidance. In addition, the wear to the bearings over the service life of the power tool can be reduced and the play in the bearings minimized.
In an advantageous configuration, the sensor device senses a blockage by means of a control and regulation unit that is arranged in the housing or on the electronic unit and has corresponding evaluation electronics, and influences the motorized drive unit. In particular in connection with rotating tools, as are used in hand-held electric tools such as drills, hammer drills, angle grinders, polishing appliances or the like, this is of considerable importance in order to comply with safety-related provisions and standards. In this case, the at least one sensor can be an acceleration sensor, yaw rate sensor and/or gyro sensor. However, other sensors, known from the prior art, for vibration and motion detection are also conceivable.
A particularly simple and cost-effective possibility for vibration damping or reduction results in that the at least one resilient element is held on at least one protrusion of the bearing. In this way, the bearings already used in or on the housing of the power tool and/or on the sensor device and/or on the electronic unit can optionally be used without further modifications, as long as there is sufficient space for the resilient element. In this case, the at least one resilient element engages around the at least one protrusion and/or has a cutout into which the at least one protrusion projects.
In a particularly advantageous manner, the at least one resilient element is configured as an O-ring or a heat-shrink tube. However, depending on the requirements placed on vibration damping or reduction and the local conditions, use can also be made of a spring, a thermoplastic polymer injected into the bearing or a non-shape-related resilient element, for example a putty, wax paste or silicone paste or the like. Shape-related resilient elements, such as rubber buffers or other corresponding elastomers in a wide variety of forms, for example in the form of a cuboid, cube, ellipsoid, sphere, dumbbell, pyramid, tetrahedron, octahedron, cuboctahedron, or the like, are also conceivable.
The sensor device can be used in or on a wide variety of power tools, but preferably in or on portable power tools or power tools that operate in a substantially autonomous manner, in which vibrations or oscillations of the power tool occur on account of a motorized drive which is configured for example as an electric motor, in particular as an AC, DC or EC motor, as a piezo drive or as a combustion engine. Hybrid forms of drive are likewise conceivable.
Further advantages of the disclosure can be gathered from the features specified in the drawing and the following description.
The disclosure is explained by way of example in the following text with reference to
In the figures
The sensor device 14 serves to detect an uncontrolled blockage of the hammer drill 11. The uncontrolled blockage can occur for example when the application tool 30 jams in a workpiece (not illustrated in more detail) to be machined. A reaction torque that acts on the housing 12 can in this case exceed a holding force by a user. As a result, the housing 12 rotates in an uncontrolled manner about a rotation axis 31 of the application tool 30. In this case, there is an increased risk of injury to the user.
The sensor device 14, illustrated in more detail in a first exemplary embodiment in
In the exemplary embodiment shown according to
According to the prior art, the sensor device 14 is connected fixedly to the housing 12 via bearings 42. These bearings 42 are provided both on the sensor device 14 and on the housing 12 (cf.
Therefore, according to the disclosure, provision is made for at least one bearing 42 to be provided in the housing 12 of the power tool 10 and/or on the sensor device 14 and/or on the electronic unit 32, said bearings 42 having at least one resilient element 44 for damping or reducing vibrations between the housing 12 and the electronic unit 32, in order to significantly reduce or entirely avoid misdetection of particular, in particular safety-related operating conditions. Furthermore, as a result, the wear to the bearings 42 over the service life of the power tool 10 can be reduced and the play in the bearings 42 minimized. In the exemplary embodiment according to
Instead of the O-ring 46, it is also optionally possible to use a heat-shrink tube as the resilient element 44. Depending on the requirements placed on vibration reduction and the local conditions, it is also possible to use springs or the like, however.
Alternatively or in addition to engaging around the protrusion 48, the resilient element 44 can also have a cutout 50 into which the at least one protrusion 48 projects in order to be held. This is shown for example in the second exemplary embodiment according to
Finally, it should also be noted that the exemplary embodiments shown are not limited to
Number | Date | Country | Kind |
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10 2015 205 172.2 | Mar 2015 | DE | national |