Hand-held impact power tool with power control adapted to contact pressure

Abstract

The invention relates to a hand-held percussion power tool, preferably a hammer drill or chisel hammer, having an electric drive unit (4) for generating a rotary drive movement, a downstream percussion mechanism unit (5) converting the rotary drive movement into an alternating linear percussion movement, the invention relates to a linear percussion mechanism unit (5) which acts on a punching drill or chisel tool (8) which is removably locked in a downstream tool holding unit (6), in which a housing arrangement is provided, comprising an outer housing (1) with a handle (2) and a base housing (3) which is resiliently mounted relative thereto in a percussion force direction (FA) for receiving at least the percussion mechanism unit (5), wherein an electronic control unit (10) is provided for the power control of the electric drive unit (4), which is adapted to a contact pressure, starting from the current contact pressure on the hammer drill or chisel hammer (8) determined by means of a sensor (11) during the machining of the workpiece, wherein the sensor (11) is located on an electronic circuit board (12) which at least partially forms the electronic control unit (10) and is accommodated in the outer housing (1), such that the sensor (11) is positioned in the vicinity of a detection element (13) on the base housing (3) side.

Description

Field of the Invention

[0001] The present invention relates to a hand-held impact power tool, such as a hammer drill or a chipping hammer, which includes an electric motor drive unit for generating a rotational drive movement, and a subsequent impact mechanism unit that converts the rotational drive movement into an alternating linear impact movement, the linear impact movement impacting a percussion drill or a chipping hammer releasably locked in a subsequent tool receiving unit, wherein the housing assembly includes an outer housing having a handle and a base housing elastically mounted in the direction of the impact force, the housing assembly being arranged to accommodate at least the impact mechanism unit, and wherein an electronic control unit is also provided for performing power adjustment of the electric motor drive unit adapted to the pressing force on the percussion drill or the chipping hammer determined by means of a sensor during machining of a workpiece.

[0002] The application field of the present invention mainly extends to hand-held hammer drills or chipping hammers, which are provided with an electric motor drive unit. Such hand-held power tools generate a linear alternating working movement via a mechanical impact mechanism, i.e., a reciprocating movement for the impact tool, which is designed as a mortise chisel in the case of a chipping hammer and as a percussion drill in the case of a hammer drill, for preferably machining mineral materials, such as stone, concrete, etc. Due to the interaction with the workpiece and the operator's arm system as well as the internal mass and stiffness distribution, a hand-held power tool capable of driving the tool with normal impacts has a complex vibration behavior, which must be suppressed as much as possible.

[0003] For this reason, a composite housing assembly of interest is used here, which is equipped with a molded handle on its outer housing and is combined with a base housing elastically mounted. In the base housing, at least the impact mechanism unit is accommodated, as well as a tool receiving unit attached thereto and extending from the base housing, and usually also an electric drive unit. This composite housing concept is used to reduce vibrations because the working movement generated by the impact mechanism unit is not completely transmitted to the handle and thus to the operator, but is damped via spring elements arranged between these housing elements.

[0004] The power adjustment of the electric motor drive unit adapted to the pressing force, which is usually additionally implemented, causes the power of the drive unit to increase as the pressing force increases, which is automatically carried out by the electronic control unit. Background Art

[0005] The generally known prior art discloses a hand-held impact power tool having an impact performance adapted to the pressing force, and different concepts for obtaining the pressing force currently applied by the operator on the workpiece by this hand-held impact power tool are known. In particular, in the case of a composite housing assembly consisting of a base housing and an outer housing, the base housing and the outer housing are pre-tensioned relative to each other by a spring device. Advantageously, in the case where the spring characteristics are known, for example by means of a displacement sensor system, the pressing force is derived from the relative movement between the base housing and the outer housing.

[0006] In known sensor assemblies for detecting such relative movement, both the sensor and the corresponding detection element are usually arranged as separate components in the hand-held power tool. The sensor is equipped with electronics for processing the measurement data and transmitting this data in digital or analog form to the electronic control unit of the hand-held power tool.

[0007] DE 10 2012 005 803 A1 discloses a general hand-held impact power tool having an impact mechanism unit driven by a drive unit and an operator's handle formed on the housing. A force detection device can detect the pressing force of the operator on the handle. If the detected pressing force exceeds a predetermined working impact force limit value, the impact frequency of the impact mechanism can be increased to a predetermined working frequency. If the detected pressing force of the operator drops below a predetermined idling impact force limit, the impact frequency can be reduced to a predetermined idling speed. For this purpose, the force detection device has a force sensor which is arranged in the force flow between a contact surface provided on the one hand on a holding device of the operator's hand and on the other hand the drive unit and / or the impact mechanism unit and / or the tool receiving unit, and generates a signal depending on the pressing force of the operator. The force sensor is preferably a displacement sensor by means of which the relative movement of the handle relative to the drive unit and / or the impact mechanism unit can be detected, wherein this relative movement depends on the pressing force of the operator.

[0008] Furthermore, DE 197 38 092 C1 discloses a power regulation adapted to the pressing force for a hand-held impact power tool, wherein the force sensor of the hand-held impact power tool is directly arranged below a housing part formed on the handle. The sensor surface of the force sensor faces the housing, which has a thinner wall in the region of the force sensor than the housing part surrounding this region. The signal corresponding to the actuating force of the force sensor is detected by the electronic control unit, and if the signal is constant, the operating parameter corresponding to this actuating force is automatically maintained within a selectable time period. The action range of the force sensor can be pre-set using an adjustment wheel equipped with an electronic control unit in order to influence the operating parameter.

[0009] All of these sensor concepts of the prior art have proven to be relatively complex and / or error-prone, especially with regard to the data lines extending between the sensor and the electronic control unit, which are exposed to interfering magnetic fields from the drive unit, etc.

[0010] The object of the present invention is to further improve a hand-held impact power tool of a general type with power regulation adapted to the pressing force, such that a simple design with reduced fault sensitivity is achieved. Summary of the Invention

[0011] This object is achieved by means of a hand-held impact power tool as described in the preamble of claim 1 in combination with its characterizing features. The following dependent claims describe advantageous developments of the present invention.

[0012] The technical principle of the present invention is that a power regulation sensor adapted to the pressing force is directly arranged on a circuit board, which at least partially forms an electronic control unit and is accommodated in the outer housing of a composite housing assembly, such that the sensor is positioned adjacent to a detection element arranged on the base housing side, i.e., within the range where its sensor is effective.

[0013] Advantageously, by arranging the electronic circuit board of the electronic control unit in the hand-held power tool such that the sensor is directly integrated on the electronic circuit board, the complexity of the power regulation adapted to the pressing force is reduced. The electronic circuit board is arranged on the outer housing side, and the detection element is located in the base housing. The electronic circuit board will be installed in the outer housing such that the distance to the detection element on the base housing is as small as possible.

[0014] Due to the constantly changing magnetic field of the motor, the electric motor drive unit adjacent to the sensor usually generates strong interference to the data lines. However, since the sensor according to the present invention is directly arranged on the electronic circuit board, these interference fields only cause very little interference to the data lines between the sensor and the electronic control unit, which is also at least partially arranged on the same electronic circuit board, because the length of the data lines is reduced to a minimum. This eliminates the need for complex shielding measures for such data lines. At the same time, the manufacturing cost is significantly reduced because the sensor does not require any additional electronics, such as measurement amplifiers or converters, and there is no cable connection between the sensor and the electronic control unit. In addition to the pure part cost, additional assembly work for attachment and cable laying can be saved. This not only reduces the manufacturing workload but also reduces the mechanical robustness of the sensor concept for power regulation adapted to the pressing force, because in the case of the existing high vibration level of the hand-held impact power tool, additional data lines are always vulnerable to mechanical damage, which can lead to device communication interruption and thus device failure, which is avoided by the solution according to the present invention.

[0015] According to a first preferred embodiment of the present invention, an electronic circuit board with sensors is arranged on the upper side within the housing body such that the electronic circuit board extends parallel to the impact axis but spaced apart from the impact axis. This arrangement is suitable for a housing shape that provides sufficient space for accommodating the electronic circuit board on the upper side.

[0016] According to a second preferred embodiment, it is proposed to arrange the electronic circuit board with sensors on the intermediate space between the base housing and the outer housing such that the electronic circuit board extends transversely to the impact axis. This arrangement is particularly suitable for a housing design with a relatively large transverse extent.

[0017] According to a third preferred embodiment, it is proposed that the electronic circuit board with sensors is arranged on the lower side of the outer housing such that the electronic circuit board extends parallel to the impact axis but spaced apart from the impact axis. This arrangement is particularly suitable for a housing shape for accommodating a short motor. Additionally, it is also conceivable to arrange the electronic circuit board with sensors between the upper side and the lower side, i.e., on the flank side of the outer housing, such that the electronic circuit board also extends parallel to the impact axis but spaced apart from the impact axis here.

[0018] The sensor for detecting the relative movement between the base housing and the outer housing is preferably designed as a 3D magnetic field sensor. This type of sensor is capable of detecting distance changes in both the longitudinal and transverse directions and is thus equally suitable for all mounting positions of the electronic circuit board. A permanent magnet element can be used as the associated detection element, which is attached to the base housing as close as possible to the sensor.

[0019] Alternatively, the sensor can also be designed as an inductive sensor and the associated detection element can also be formed by the metal / magnetic component structure of the base housing or the components accommodated in the base housing.

[0020] If the electronic control of the hand-held power tool is to be distributedly arranged on multiple electronic circuit boards, it is recommended to arrange at least one logic element of the electronic control unit on the electronic circuit board with sensors, while the remaining power units can be placed outside the electronic circuit board in the outer housing or the base housing of the hand-held power tool, close to the drive device. This measure improves the flexibility of accommodating electronic components in a particularly compact housing shape.

[0021] If there is sufficient mounting space, an electronic control unit that is completely arranged on the electronic circuit board should preferably be provided in order to maximize the functional reliability of the electronic device and reduce the installation cost.

[0022] Preferably, the sensor should be soldered directly to the electronic circuit board. This involves not only establishing the electrical connection of the sensor connection, but also the sensor housing, which can thus be reliably mounted on the electronic circuit board. The electronic circuit board itself can be releasably and thus interchangeably attached to the inside of the outer housing, for example, by means of conventional threaded connections on the corresponding support structure. Description of the Drawings

[0023] Other measures for improving the present invention will be explained in more detail below with reference to the drawings in connection with the description of the preferred exemplary embodiments of the present invention. In the drawings: Figure 1 A schematic side view showing a first embodiment of a hand-held percussion power tool according to the present invention with power regulation adapted to the pressing force, Figure 2 A schematic side view showing a second embodiment of a hand-held percussion power tool according to the present invention with power regulation adapted to the pressing force, Figure 3 A schematic side view showing a third embodiment of a hand-held percussion power tool according to the present invention with power regulation adapted to the pressing force, and Figure 4 A schematic side view showing a fourth embodiment of a hand-held percussion power tool according to the present invention with power regulation adapted to the pressing force. Detailed Description of the Invention

[0024] According to Figure 1 , the hammer drill has a composite housing assembly consisting of an outer housing 1 with a handle 2 and a base housing 3 elastically mounted in the direction of the impact force F A In the base housing, an electric motor drive unit 4 and a subsequent impact mechanism unit 5 are accommodated. An outwardly protruding tool receiving unit 6 is arranged on the impact mechanism unit. The percussion drill 8 is releasably locked in the tool receiving unit 6 along the impact axis 7. The impact mechanism unit 5, the tool receiving unit 6, and the percussion drill 8 are located on a common impact axis 7. The electric motor drive unit 4 is arranged transversely to the impact axis and is connected to the impact mechanism unit 5 via a gear device. The overall arrangement of the various functional units forms the center of gravity S.

[0025] The manual operation switch 9 for turning on and off the electric motor drive unit 4 is also arranged on the handle 2 of the outer housing 1, and this switch is located on the side of the base housing 3. When the hand-held power tool is not being operated, there is a distance L between the outer housing 1 and the base housing 3, and this distance determines the spring travel.

[0026] The hammer drill is equipped with an electronic control unit 10 for performing power regulation adapted to the pressing force on the electric motor drive unit 4. The sensor 11 determines the distance between the outer housing 1 and the base housing 3 in the direction of the impact force FA the distance between the resiliently mounted base housings 3, which distance represents in a manner known per se a measure of the clamping force currently applied to the percussion drill 8 when machining a workpiece.

[0027] The sensor 11, which is designed here as a 3D magnetic field sensor, is fixedly arranged by soldering on an electronic circuit board 12 forming the electronic control unit 10. The electronic circuit board 12 with the sensor 11 is arranged on the upper side 14 within the outer housing 1 parallel to the impact axis 7 and positioned such that the sensor 11 is adjacent to a detection element 13 arranged on the side of the base housing 3. The detection element 13 is designed as a permanent magnet element which is embedded in the wall of the base housing 3 close to the sensor 11.

[0028] Figure 2 An embodiment is shown in which the electronic circuit board 12' with the sensor 11' attached is arranged in an intermediate space 15 between the base housing 3 and the spring housing 1. The intermediate space 15 is formed by the spring travel of a vibration decoupling device, which spring travel corresponds to the spring travel L. The electronic circuit board 12' extends transversely to the impact axis 7. The sensor 11' arranged on the side of the outer housing 1 is positioned opposite the detection element 13', wherein the two components, the sensor 11' and the detection element 13', do not contact the outer housing 1 even in the end position of the retraction of the base housing 3. The remaining structure of the hand-held power tool according to the second embodiment corresponds to the first embodiment described above.

[0029] According to Figure 3 , in a third embodiment of the hand-held power tool, the electronic circuit board 12'' with the sensor 11'' is arranged inside on the lower side 16 of the outer housing 1 such that the electronic circuit board 12'' extends parallel to the impact axis 7 but spaced apart from the impact axis. This design is particularly suitable for short electric motors since there is still sufficient space below them to arrange the sensor 11'' and the corresponding detection element 13'', which detection element is positioned below the electric motor drive unit 4. Here, the remaining components of the hand-held power tool also correspond to the first embodiment.

[0030] According to Figure 4 the fourth embodiment shown in, the electronic circuit board 12''' is arranged on the flank side 17 of the outer housing 1 extending between the upper side 14 and the lower side 16 such that the electronic circuit board 12'' also extends here parallel to the impact axis 7 but spaced apart from the impact axis.

[0031] Alternatively, the electronic circuit board 12'''' can of course also be arranged inside the housing on the flank side (not numbered) opposite the flank side 17.

[0032] The drawings show in one image all the above options for a space-saving arrangement of the electronic circuit boards 12, 12', 12'', 12''', 12'''' according to the invention.

[0033] The invention is not limited to the above three exemplary embodiments. On the contrary, modifications thereof are also conceivable, which are covered by the scope of protection of the following claims. For example, an inductive sensor can also be used instead of the 3D magnetic field sensor, provided that the inductive sensor can provide sufficiently reliable measurement values regarding the current distance situation between the housing 1 and the base housing 2 for the installation position and the detection environment.

[0034] List of reference numerals 1 Housing 2 Handle 3 Base housing 4 Drive unit 5 Impact mechanism unit 6 Tool receiving unit 7 Impact axis 8 Percussion drill or chisel hammer 9 Switch 10 Electronic control unit 11 Sensor 12 Electronic circuit board 13 Detection element 14 Upper side 15 Intermediate space 16 Lower side 17 Flank side F A Impact force direction S Center of gravity L Distance

Claims

1. A hand-held impact power tool, preferably a hammer drill or a chisel hammer, comprising an electric motor drive unit (4) for generating a rotary drive motion, a subsequent impact mechanism unit (5) converting the rotary drive motion into an alternating linear impact motion, the linear impact motion impacting an impact drill or a chisel hammer (8) releasably locked in a subsequent tool receiving unit (6), wherein the housing assembly comprises an outer housing (1) having a handle (2) and a radially extending outer housing (2) extending in the direction of the impact force (F A ), the housing assembly being configured to accommodate at least the impact mechanism unit (5), wherein an electronic control unit (10) is also provided for regulating the power of the electric motor drive unit (4) adapted to the pressing force based on the current pressing force on the impact drill or hammer (8) determined by means of sensors (11, 11', 11'') when machining a workpiece, It is characterized in that The sensor (11, 11', 11") is arranged on an electronic circuit board (12, 12', 12'', 12''', 12'''') which at least partially forms the electronic control unit (10) and is accommodated in the outer shell (1), so that the sensor (11) is positioned adjacent to a detection element (13, 13', 13") arranged on the side of the base shell (3).

2. The handheld impact power tool according to claim 1, It is characterized in that The electronic circuit board (12) with the sensor (11) is arranged on the upper side (14) of the outer housing (1) in such a way that the electronic circuit board (12) runs parallel to the impact axis (7) but at a distance therefrom.

3. The handheld impact power tool according to claim 1, It is characterized in that The electronic circuit board (12') with the sensor (11') is arranged in or on an intermediate space (15) between the base housing (3) and the outer housing (1) such that the electronic circuit board (12') extends transversely to the impact axis (7).

4. The handheld impact power tool according to claim 1, It is characterized in that The electronic circuit board (12") with the sensor (11") is arranged on the underside (16) of the outer housing (1) such that the electronic circuit board (12") extends parallel to the impact axis (7) but at a distance therefrom.

5. The handheld impact power tool according to claim 1, It is characterized in that The electronic circuit board (12'', 12'''') with the sensor (11'') is arranged on one of the flank sides (17) of the outer housing (1) extending between the upper side (14) and the lower side (16), so that the electronic circuit board (12'') extends parallel to the impact axis (7) but at a distance therefrom.

6. The handheld impact power tool according to claim 1, It is characterized in that The sensor (11, 11', 11") is designed as a 3D magnetic field sensor and the associated detection element (13, 13', 13") is designed as a permanent magnet element.

7. The handheld impact power tool according to claim 1, It is characterized in that The sensor (11, 11', 11'') is designed as an inductive sensor and the associated detection element is formed by a component structure of the base housing (3) or a component accommodated in the base housing.

8. A hand-held impact power tool according to any one of the preceding claims, It is characterized in that The electric motor drive unit (4) is also accommodated in the base housing (3).

9. A hand-held impact power tool according to any one of the preceding claims, It is characterized in that The logic elements of the electronic control unit (10) are arranged on the electronic circuit board (12, 12', 12'', 12''', 12''''), while the power unit is accommodated outside the electronic circuit board in the outer housing (1) or the base housing (3).

10. The hand-held impact power tool according to any one of the preceding claims 1 to 8, It is characterized in that The electronic control unit (10) is completely arranged on the electronic circuit board (12, 12', 12'', 12''', 12'''') of the outer shell (1).

11. A hand-held impact power tool according to any one of the preceding claims, It is characterized in that The sensor (11, 11', 11'') is fixedly attached to the electronic circuit board by welding.

Images