Patent Application
20180193972
The invention relates to a portable power tool having a motor axis and a working axis.
A portable power tool according to the preamble of claim 1 is already known from the prior art.
The battery-operated grinding appliance according to the invention according to the preamble of claim 1 is realized, in particular, in the form of an angle grinder. An electronically commutated electric motor drives a motor shaft, wherein the motor shaft, with the electronically commutated electric motor, defines a motor axis. The motor axis in this case is a theoretical axis, which is coaxial with the motor shaft. A working shaft carries a machining tool, wherein the working shaft defines a working axis. The working axis in this case is a theoretical axis, which is coaxial with the working shaft. It is proposed that the motor axis and the working axis are disposed, in particular, in a parallel manner, spaced apart from one another, and are connected to each other via a belt drive. “In a parallel manner” is to be understood here to mean, in particular, that the motor axis and the working axis are at an angle in relation to each other that is between 0 and 5°. Use of a belt drive makes it possible, advantageously, to achieve a low rotational speed of the machining tool with a high rotational speed of the electronically commutated electric motor, with the result that the machining tool can have, for example, a greater diameter.
Moreover, the battery-operated grinding appliance according to the invention can be realized in a very compact manner.
Advantageously, the machining tool is a grinding, parting or roughing disk that has a diameter ddisk. Advantageously, the rotational speed ndisk of the machining tool may be between 7500 rpm and 15500 rpm, especially between 10000 rpm and 13500 rpm, and particularly preferably may be 11000 rpm, wherein a motor rotational speed is from 15000 to 30000, in particular from 17500 to 22000 rpm, but in particular is less than 13000 rpm. As a result, particularly advantageously, the diameter ddisk of the machining tool may be 100 to 150 mm, but preferably 115 to 125 mm. The specifications for the diameter ddisk of the machining tool do not take account of any possible production tolerances. This is achieved, advantageously, in that the belt drive has a reduction ratio of 1.5 to 3.5, especially of between 1.8 and 2.5, but preferably of 2.1. Thus, advantageously, the battery-operated grinding appliance according to the invention can be realized in a very compact manner.
Advantageously, the electronically commutated electric motor is an internal-rotor motor. As a result, high rotational speeds can be achieved, with a high power density. It is also conceivable, however, for the electronically commutated electric motor to be realized as an external-rotor motor.
In the preferred embodiment according to the invention, the battery-operated grinding appliance has a rechargeable battery, which serves as an energy source for the battery-operated grinding appliance. Advantageously, the rechargeable battery has a battery voltage that is between 3.6 and 40 V, in particular between 4.0 and 36 V, especially between 7.2 and 20 V, particularly preferably between 8.0 and 18 V, but preferably 10.8 V, but particularly preferably 12 V.
In a further embodiment according to the invention, the battery-operated grinding appliance has an actuator element, wherein the actuator element acts on the belt drive via a push rod.
Advantageously, the battery-operated grinding appliance is of a weight of between 400 and 750 g, in particular between 450 and 650 g, preferably between 500 and 550 g. This weight excludes the weight of the rechargeable battery. The rechargeable battery is of a weight of between 150 and 400 g.
Further advantages and expedient embodiments are given by the description of the figures and the drawings.
Exemplary embodiments of a portable power tool according to the invention are shown in the drawings.
There are shown:
Component parts that are the same in the differing exemplary embodiments are denoted by the same references.
In the form of an angle grinder means, in this case, that the battery-operated grinding appliance 10 is an electrically driven, portable power tool having a rotating round grinding disk, but does not have a right-angle gear transmission. Moreover, the external design of one angle grinder is similar.
Disposed in a first housing part 14 there is an electronically commutated electric motor 16, which drives a motor shaft 18. The motor shaft 18, together with the electronically commutated electric motor 16, forms a motor axis 20. The motor axis 20 is a theoretical axis, which is coaxial with the motor shaft 18. A second housing part 22 is connected to the first housing part 14. The second housing part 22 is realized as a handle. A working shaft 24 is disposed in the first housing part 14, and carries a machining tool 26. In the exemplary embodiment, the machining tool 26 is a grinding, parting or roughing disk. A protective hood 27 covers the machining tool 26, at least partly. As can be seen in
The working shaft 24 defines a working axis 38, which is coaxial with the working shaft 24. The advantage of the design according to the invention consists in that the motor axis 20 and the working axis 38 are disposed in a parallel manner in relation to each other. “In a parallel manner” is to be understood here to mean that the two axes (20, 38) are disposed at an angle in relation to each other that is between 0 and 5°.
As can be seen in
As a result of the transmission of the rotational speed of the electronically commutated electric motor 16 to the working shaft 24 by the belt drive, in the embodiment according to the invention the rotational speed ndisk of the machining tool 24 is advantageously between 7500 rpm and 15500 rpm, especially between 10000 rpm and 13500 rpm, and preferably 11000 rpm, with a motor rotational speed of from 15000 rpm to 30000 rpm, but especially between 17500 and 22000 rpm. As a result, advantageously, the diameter ddisk of the machining tool 24 can be between 100 and 150 mm, but preferably between 115 and 125 mm. The specifications for the diameter ddisk of the machining tool do not take account of any possible production tolerances.
In the embodiment according to the invention, the belt drive 28 has a reduction ratio of from 1.5 to 3.5, especially from 1.8 to 2.5, but preferably of 2.1. In particular, however, the reduction ratio of the belt drive 28 is is adaptable.
In the exemplary embodiment, the electronically commutated electric motor 16 is realized as an internal rotor. In motors of this type, on the motor housing there is a stator, which carries the current-carrying windings. A rotor, which carries the permanent magnets, is connected to the motor shaft 18. The advantages of the internal-rotor motor are a high achievable rotational speed together with a high power density. It is also conceivable, however, for the electronically commutated electric motor 16 to be realized as an external-rotor motor.
Disposed on the first housing 14 there is a switching element 40. The switching element 40 is provided for switching on the battery-operated grinding appliance 10. In the exemplary embodiment, the switching element 40 is realized as a switch button. Upon actuation of the switch button 40, an internal switch 44, which switches on an electronic system 46, is actuated via an internal switching slide 42. The electronic system 46 energizes and/or controls, by closed-loop and/or open-loop control, the electronically commutated electric motor 16.
A rechargeable battery 50 is disposed on the second housing part 22. The rechargeable battery 50 serves to supply energy for the battery-operated grinding appliance 10.
As can be seen in
The battery voltage is in a range of between 3.6 and 40 V, in particular between 4.0 and 36 V, especially between 7.2 and 20 V, particularly preferably between 8.0 and 18 V. Preferably, the battery voltage is 10.8 V, but particularly preferably 12 V. The values of the battery voltage do not take account of any possible battery voltage fluctuations.
The rechargeable battery 50 is composed, in particular, of lithium-ion battery cells. The rechargeable battery 50 in this case comprises one or more rows of battery cells, which in turn are connected in parallel and/or in series to each other. Each individual cell is of a length of approximately 65 mm, and of a diameter of approximately 18 mm. It is also conceivable, however, for a cell to be of a length of from 65 to 70 mm, and of a diameter of from 14 to approximately 20 mm. These specifications do not take account of any possible production tolerances.
Lithium-ion rechargeable batteries are characterized by a high energy density and thermal stability, even at high loads, which means a high power output. A further major advantage is the low self-discharge, which has the effect that the rechargeable batteries are also ready for use even in the case of long periods of non-use. Ensuing from these advantages are the advantages of the application according to the invention, in particular that, on the one hand, the battery-operated grinding appliance 10 can be small and compact in its dimensions and, on the other hand, provide high power outputs.
It is also conceivable, however, for the rechargeable battery 50 to be composed of lithium-air cells, of lithium-sulfur cells, lithium-polymer cells or the like. Furthermore, the rechargeable battery 50 may be realized in a geometric embodiment other than that shown, such as, for example, in an angular embodiment.
In the exemplary embodiment in
Furthermore, it is possible, by actuation of a switching element 40, to activate a blocking device in order to lock the working shaft 24. The spindle locking may be effected in a form-fitting and/or force-fitting manner. In this case, there is a latching disk 55 attached to the working shaft 24. The spindle locking may be effected automatically. It is also conceivable, however, for the spindle locking to be manually actuated.
A sensor unit 60 is realized, in particular, as a Hall sensor. The sensor unit 60 determines the position of the rotor relative to the stator of the electronically commutated electric motor 16.
In the exemplary embodiment in
When, as can be seen in
The first pulley 92 of the second pulley pair 90 is axially displaceable, against a spring force, relative to a second pulley 94 of the second pulley pair 90. If the effective diameter on the first pulley pair 80 is increased, the tension on the belt 39 is increased, and the two pulleys 92, 94 of the second pulley pair 90 are forced apart against their spring force. The spring force is designed such that the belt 39 does not slip at the anticipated torques. Furthermore, it is conceivable that a mechanical coupling or a further actuator is provided for adaptation of the second pulley pair 90. The belt 39 may be realized as a toothed belt, as a flat belt, as a V-belt, as a band belt, as cord belt, as a chain or the like.
The battery-operated grinding appliance 10 is of a weight of between 400 and 750 g, in particular between 450 and 650 g, preferably between 500 and 550 g. This weight excludes the weight of the rechargeable battery 50. The rechargeable battery 50 is of a weight of between 150 and 400 g.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 212 042.2 | Jun 2015 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/059770 | 5/2/2016 | WO | 00 |
