Handheld power tools

Abstract

The present invention relates to a handheld power tool (1), comprising: a drive circuit (11) for providing an adjustment signal according to the actuation of a button (12); and a control device (20) for adjusting the drive current of an electric motor (4) for the handheld power tool (1) according to the adjustment signal. The control device (20) is connected via a first wiring arrangement (21) to an electrical energy source for operating the handheld power tool (1). The drive circuit (11) is connected to the control device (20) via a second wiring arrangement (15). Drive power lines (16A, 16B) carrying the drive current for the electric motor (4) are routed via an interrupt switch (14), the interruption being associated with the button (12) for interrupting the drive current. An interference suppression capacitor (13) is connected to the drive power lines (16A, 16B) via a first node (K1) and to the second wiring arrangement (15) via a second node (K2).

Description

Technical Field

[0001] This invention relates to a handheld power tool, particularly an electric handheld power tool, such as an electric screwdriver. Background Technology

[0002] Electric handheld power tools typically have an electric motor that is powered by an electrical energy source. When a handheld power tool is operated, high-frequency interference voltages or currents may appear in the drive circuit. These interference voltages or currents can be reduced or prevented, for example, by short-circuiting an interference suppression capacitor to ground.

[0003] In conventional handheld power tools, interference suppression capacitors are often integrated into the handle with the main switch due to space constraints, and are directly wired to the phase conductor carrying the current for the electric motor, and also directly wired to the neutral conductor. This requires significant cabling expenditure.

[0004] In this context, the object of the present invention is to provide a simplified handheld power tool. Summary of the Invention

[0005] Accordingly, a handheld power tool is proposed, comprising: a drive circuit for providing an adjustment signal based on button actuation; and a control device for adjusting the drive current of an electric motor for the handheld power tool based on the adjustment signal. The control device is connected via a first wire to an electrical energy source for operating the handheld power tool, and the drive circuit is connected to the control device via a second wire. The drive power line carrying the drive current for the electric motor is routed via an interrupt switch, which is associated with a button for interrupting the drive current. An interference suppression capacitor is connected to the drive power line via a first node and to the second wire arrangement via a second node.

[0006] The advantage of this handheld power tool is the reduction in cabling costs compared to conventional solutions. Because the interference suppression capacitor is connected via a second wire, a separate line connecting the capacitor to the neutral conductor of the power source is eliminated. This also eliminates the need for a plug or socket, which might otherwise be necessary to route such wiring through the walls of the housing.

[0007] Handheld power tools can be designed to operate on mains power, which must be connected to a power supply system during operation, or to operate independently of mains power and be powered by, for example, a rechargeable battery.

[0008] Handheld power tools are designed as, for example, drills, impact drills, hammer drills, electric hammers, grinders, abrasive cutters, mixers, or saws. This list is merely illustrative and should not be construed as exhaustive.

[0009] The button is designed as a nacheilender taster, for example, requiring constant pressure to actuate. The button can also be called an on / off switch, main switch, torque controller, etc. The button is operated by the user of the handheld power tool to operate the tool.

[0010] The drive circuit provides an adjustment signal based on the button's actuation. This adjustment signal can also be called the target speed value, speed adjustment signal, control signal, etc.

[0011] The adjustment signal may include multiple discrete levels and / or the adjustment signal may be continuous. The adjustment signal, for example, corresponds to a value between 0% and 100% of the drive current. The adjustment signal is determined specifically based on the pressure applied to the button. The button has, for example, a specific actuation path; for example, the button can be pressed up to 10 mm, wherein the adjustment signal is, for example, proportional to the current button position.

[0012] The control device is connected to an electrical power source via a first wiring arrangement. For this purpose, the control device specifically includes a drive circuit. The electrical power source is, for example, a power supply system or a rechargeable battery. The first wiring arrangement includes at least two mutually insulated conductors, specifically a phase conductor and a neutral conductor. Additionally, a protective conductor may be provided. Thus, even when the button is not actuated, the handheld power tool is also supplied with electrical power via the first wiring arrangement. In this way, for example, integrated circuits, display elements, and / or other peripheral components can be permanently powered.

[0013] However, the electric motor of a handheld power tool is only supplied with power when the button is actuated. In this case, an interrupt switch acts as a safety device that completely cuts off the drive current once the button is no longer actuated or the current drops below the actuation threshold. The interrupt switch is preferably directly mechanically coupled to the button. The drive power line is an auxiliary power line that extends on one side between the control device and the interrupt switch and on the other side between the interrupt switch and the power source.

[0014] The level of the drive current is set by the control device according to the adjustment signal. In other words, the control device performs open-loop or closed-loop control of the drive current. When the adjustment signal is 100%, the electric motor is supplied with maximum power. Thus, the electric motor, for example, has maximum torque and / or maximum speed.

[0015] An interference suppression capacitor is connected between the drive power line and the second wiring arrangement. This connection to the second wiring arrangement can be made directly or via an insertion circuit, such as the drive circuit. The potential necessary for the operation of the interference suppression capacitor can, for example, circulate through the drive circuit.

[0016] According to one embodiment of the handheld power tool, the interference suppression capacitor is directly connected to the second wiring arrangement.

[0017] "Direct connection" specifically refers to the absence of any active or passive electrical components between the interference suppression capacitor and the second wiring arrangement. If the interference suppression capacitor is connected to the second wiring arrangement via a circuit that circulates through the drive circuit, this is also considered a "direct connection."

[0018] In this embodiment, the interference suppression capacitor is directly connected to the second wire arrangement via a separate line. This embodiment eliminates the possibility of connections via loop-through lines.

[0019] According to another embodiment of the handheld power tool, the interference suppression capacitor is connected to the neutral conductor potential or ground potential via a second wire arrangement.

[0020] The neutral conductor potential is particularly related to the phase conductor potential of the power supply system. The driving power lines are correspondingly connected to the phase conductors of the power supply system.

[0021] According to another embodiment of the handheld power tool, an interrupt switch is connected to a control device via a first segment of the drive power line and to an electrical energy source via a second segment of the drive power line, wherein an interference suppression capacitor is connected to the second segment of the drive power line via a first node.

[0022] The interference suppression capacitor is therefore connected to the power source. The advantage of this is that when the interrupt switch is turned off, the charge stored in the interference suppression capacitor can flow into the power source. This prevents interference or damage to components in the handheld power tool.

[0023] According to another embodiment of the handheld power tool, the interrupt switch is opened or closed upon actuation of the button.

[0024] For example, when the button is actuated by 10%-20%, the interrupt switch closes. In the case of a button with a 10mm adjustment travel, this corresponds to being actuated by 1mm-2mm.

[0025] According to another embodiment of the handheld power tool, the drive circuit, button, interference suppression capacitor, and interrupt switch are part of a common component.

[0026] Common components, especially common fastening units, such as mounting plates, etc.

[0027] Specifically, the drive circuit, interference suppression capacitor, and interrupt button can be arranged within the housing, with the button positioned on the housing in such a way that it can be actuated from the outside. The housing may preferably have a socket or plug, and a second wiring arrangement and drive power lines are routed through the socket or plug into the housing.

[0028] According to another embodiment of the handheld power tool, the drive circuit includes a circuit board on which at least one detection unit is integrated, the detection unit being coupled to a button for detecting button actuation.

[0029] The detection unit is specifically configured to detect the current position of the button and to output an adjustment signal based on the detected current position.

[0030] The detection unit includes, for example, a voltage divider that outputs an analog voltage signal based on the input voltage and the current position. Alternatively, the detection unit may include a digital converter that outputs an adjustment signal in the form of a duty cycle. In this case, the current position of the button can be detected, for example, by optical or magnetic means.

[0031] According to another embodiment of the handheld power tool, the interference suppression capacitor is integrated on the circuit board.

[0032] This further reduced cable laying costs.

[0033] According to another embodiment of the handheld power tool, the interference suppression capacitor is designed as an SMD component.

[0034] In this way, the circuit board can be installed preferably in a fully automated manner, which further improves the production process of handheld power tools.

[0035] According to another embodiment of the handheld power tool, the drive circuit is integrated into the handle of the handheld power tool and the button can be actuated from the outside of the handle.

[0036] In particular, the interrupt switch and interference suppression capacitor are also arranged in the handle along with the drive circuit.

[0037] According to another embodiment of the handheld power tool, the control device is configured to provide operating voltage for the drive circuit via a second wiring arrangement.

[0038] The drive circuit operates, for example, at a low voltage in the range of 1V to 20V.

[0039] According to another embodiment of the handheld power tool, the second wiring arrangement includes a maximum cross-section of 1 mm². 2 The preferred size is 0.5mm. 2 A more preferred size is 0.33mm. 2 The line.

[0040] Because only a small current is transmitted via the second wire, a wire with a small cross-section can be used, which reduces material costs.

[0041] According to another embodiment of the handheld power tool, the drive power line has a 1.5mm... 2 and 5mm 2 The line cross-section between them.

[0042] High current and high power can be transmitted through this line, which is beneficial for operating electric motors to generate high torque.

[0043] According to another embodiment of the handheld power tool, the interference suppression capacitor has a capacitance between 0.1 μF and 1 μF.

[0044] According to another embodiment of the handheld power tool, the interference suppression capacitor is designed as an X1 or X2 type capacitor.

[0045] X1 class capacitors are designed for voltage peaks between 2500V and 4000V, while X2 class capacitors are designed for voltage peaks up to 2500V. Attached Figure Description

[0046] The present invention will now be described with reference to exemplary embodiments and accompanying drawings, in which:

[0047] Figure 1 A schematic diagram of a handheld power tool is shown; and

[0048] Figure 2 A schematic diagram of the internal wiring of a handheld power tool is shown.

[0049] Unless otherwise specified, identical or functionally identical elements in the figures are indicated by the same reference numerals. Detailed Implementation

[0050] Figure 1 A handheld power tool 1 is schematically shown, designed as a hammer drill in this example. The hammer drill 1 has a tool assembly 2 into which a drill bit 3 can be inserted as a tool. The primary drive of the hammer drill 1 forms an electric motor 4 that drives the impact mechanism 5 and the drive shaft 6. The user can guide the hammer drill 1 via the handle 8 and operate it via the button 12. During operation, the hammer drill 1 causes the drill bit 3 to rotate continuously around the working axis, thereby driving the drill bit 3 into the substrate along the working axis.

[0051] Electrical components 10, which enable various functions, are arranged in the handle 8. The drive circuit 11 is configured to provide an adjustment signal SIG based on the actuation of the button 12 (see [link]). Figure 2For this purpose, the drive circuit 11 is connected to the control device 20 via a second wiring arrangement 15. Specifically, the adjustment signal SIG is transmitted via the second wiring arrangement 15. The drive circuit 11 provides the adjustment signal SIG based on the current position of the button 12, which is specifically designed as a trailing button. The combination of button 12 and drive circuit 11 can also be referred to as a speed controller. The electrical arrangement 10 further includes an interrupt switch 14 arranged in the drive power lines 16A, 16B, which carry the drive current for the electric motor 4. The interrupt switch 14 is connected to the button 12 and is opened or closed according to the actuation of the button 12. The interrupt switch 14 ensures that the electric motor 4 is powered only when the button 12 is actuated. Furthermore, the arrangement 10 includes an interference suppression capacitor 13, one end of which is connected to the drive power lines 16A, 16B, and the other end to the second wiring arrangement 15. In this example, the connection to the second wiring arrangement 15 is achieved via the drive circuit 11.

[0052] Tool assembly 2 has a sleeve into which one end of drill bit 3 can be inserted. Torque is provided by electric motor 4 and transmitted to the sleeve via a drive system. The drive system includes, for example, an output shaft 6 and a transmission device located between motor 4 and drive shaft 6. The transmission device can adapt, for example, the rotational speed of motor 4 to the desired rotational speed of drill bit 3.

[0053] The speed and / or torque of the electric motor 4 are regulated by the control device 20 according to the adjustment signal SIG. In other words, the control device 20 controls the electric motor and / or adjusts it to a target value. The control device 20 is connected to a connection terminal 24 via a first wiring arrangement 21, which can be connected to a power supply system (not shown) via a plug 23. Alternatively, the hammer drill 1 can also be powered by a rechargeable battery (not shown). The power consumption (i.e., operating value) of the electric motor 4 during operation preferably corresponds approximately to the rated power of the electric motor 4, thereby achieving an optimal power-to-weight ratio. The electric motor 4 is particularly a mechanically commutated general-purpose motor and / or an electronically commutated motor.

[0054] Figure 2 A handheld power tool 1 is shown (e.g.) Figure 1 A schematic diagram of an exemplary embodiment of the internal wiring of the hammer drill 1. The handheld power tool is, for example, a mains-powered handheld power tool 1, which can be connected to a power supply system (not shown) via a plug 23. In this example, the phase conductor L and the neutral conductor N are provided via a connection terminal 24, which is specifically arranged in the housing 9 of the handheld power tool 1 (see [reference]). Figure 1 )middle.

[0055] The control device 20 is connected to the connection terminal 24 and two phases L and N of the power supply system via a first wiring arrangement 21. Therefore, once the plug 23 is connected to the power supply system, the control device 20 can be supplied with electrical power. The first wiring arrangement 21 includes a cross-section up to 5 mm². 2 The control device 20 includes, for example, a transformer (not shown), configured to generate and provide a low voltage. The low voltage is, for example, one or more voltage values ​​between 1V and 20V. For example, integrated components such as control units (ASICs: Application-Specific Integrated Circuits, PLCs: Programmable Logic Controllers, CPUs: Central Processing Units), memory units (ROMs: Read-Only Memory, RAMs: Random Access Memory), display devices (LCDs: Liquid Crystal Displays), and lighting devices (LEDs: Light Emitting Diodes) can operate at low voltage.

[0056] Specifically, the drive circuit 11 is connected to the control device 20 via a second wiring arrangement 15 and is thereby supplied with a low voltage. In this example, the second wiring arrangement 15 includes three separate lines N, V, and SIG, where lines N and V correspond to the low voltage poles, and the adjustment signal SIG is transmitted via a third line. In this example, the low voltage is related to the neutral conductor potential of the power supply system, but this is not necessarily the case. In embodiments, additional lines may be provided, for example, to provide an additional potential. The drive circuit 11 is coupled to the button 12 and configured to provide the adjustment signal SIG according to the actuation of the button 12. For this purpose, the drive circuit 11 specifically includes a detection unit 17, which in this example is designed as a voltage converter. The lines N, V, and SIG of the second wiring arrangement 15 have, for example, a diameter of 0.33 mm. 2 The line cross section.

[0057] Button 12 is further connected to interrupt switch 14. When button 12 is actuated, for example, pressed 10%, interrupt switch 14 closes. Interrupt switch 14 is connected to control device 20 via a first segment 16A of drive power line and to connection terminal 24 of power supply system and phase conductor L via a second segment 16B of drive power line. Drive power lines 16A and 16B have a diameter of 3 mm. 2 The cross-section of the interference suppression capacitor 13 is shown. Interference suppression capacitor 13 is connected to the second segment 16B of the drive power line via a first node K1, and to the second wire arrangement 15 via a second node K2, in this example connected to the neutral conductor potential N circulating through the drive circuit 11. Interference suppression capacitor 13 has a capacitance of 0.22 μF and can withstand a peak voltage of 4000 V (Class X1), and is therefore configured to filter out high-frequency voltage fluctuations that may occur during operation of the electric motor 4 (see [link to relevant documentation]). Figure 1 ).

[0058] The drive circuit 11, button 12, interference suppression capacitor 13, and interrupt switch 14 preferably form a common component 10. In a preferred embodiment, the drive circuit 11 is designed as a circuit board, wherein the interference suppression capacitor 13 is preferably integrated on the circuit board as an SMD component (SMD: surface mount device). The drive circuit 11 may have other electronic components, such as LEDs, torque sensors, acceleration sensors, temperature sensors, etc., or may be configured for the operation of these other electronic components.

[0059] List of reference numerals

[0060] 1. Handheld power tool (hammer drill)

[0061] 2. Tool assemblies

[0062] 3 tools

[0063] 4 motors

[0064] 5. Impact Mechanism

[0065] 6 drive shafts

[0066] 7 Rechargeable batteries

[0067] 8 handles

[0068] 9. Shell

[0069] 10 Arrangement

[0070] 11. Drive Circuit

[0071] 12 buttons

[0072] 13 Interference suppression capacitor

[0073] 14 Interrupt Switch

[0074] 15 Second wiring arrangement

[0075] Section 16A

[0076] Section 16B

[0077] 17 Voltage Divider

[0078] 20 Control devices

[0079] 21 First wire arrangement

[0080] 23 plugs

[0081] 24 Connection terminals

[0082] K1 node

[0083] K2 node

[0084] L-phase conductor

[0085] N neutral conductor

[0086] SIG modulation signal

[0087] V Low voltage potential

Claims

1. A handheld power tool (1), comprising: A drive circuit (11) is used to provide an adjustment signal (SIG) according to the actuation of the button (12). Control device (20) for adjusting the drive current of the electric motor (4) of the handheld power tool (1) according to the adjustment signal (SIG), wherein, The control device (20) is connected via a first wiring arrangement (21) to an electrical power source for operating the handheld power tool (1). The drive circuit (11) is connected to the control device (20) via a second wire arrangement (15). The drive power lines (16A, 16B) carrying the drive current for the electric motor (4) are routed via an interrupt switch (14), which is connected to the button (12) for interrupting the drive current, and wherein, Interference suppression capacitor (13) is connected to the drive power line (16A, 16B) via a first node (K1) and to the second wire arrangement (15) via a second node (K2).

2. The handheld power tool as described in claim 1, characterized in that, The interference suppression capacitor (13) is directly connected to the second wire arrangement (15).

3. The handheld power tool as described in claim 1 or 2, characterized in that, The interference suppression capacitor (13) is connected to the neutral conductor potential (N) or ground potential via the second wire arrangement (15).

4. The handheld power tool as described in claim 1 or 2, characterized in that, The interrupt switch (14) is connected to the control device (20) via the first section (16A) of the drive power line and to the power source via the second section (16B) of the drive power line, wherein the interference suppression capacitor (13) is connected to the second section (16B) of the drive power line via the first node (K1).

5. The handheld power tool as described in claim 1 or 2, characterized in that, The interrupt switch (14) is opened or closed according to the actuation of the button (12).

6. The handheld power tool as described in claim 1 or 2, characterized in that, The drive circuit (11), the button (12), the interference suppression capacitor (13), and the interrupt switch (14) are part of a common component (10).

7. The handheld power tool as described in claim 1 or 2, characterized in that, The drive circuit (11) includes a circuit board on which at least one detection unit (17) is integrated, which is connected to the button (12) for detecting the actuation of the button (12).

8. The handheld power tool as described in claim 7, characterized in that, The interference suppression capacitor (13) is integrated on the circuit board.

9. The handheld power tool as described in claim 8, characterized in that, The interference suppression capacitor (13) is designed as an SMD component.

10. The handheld power tool as described in claim 1 or 2, characterized in that, The drive circuit (11) is integrated in the handle (8) of the handheld power tool (1), and the button (12) can be actuated from outside the handle (8).

11. The handheld power tool as described in claim 1 or 2, characterized in that, The control device (20) is configured to provide an operating voltage (V) to the drive circuit (11) via the second wire arrangement (15).

12. The handheld power tool as described in claim 1 or 2, characterized in that, The second wiring arrangement (15) includes wires with a maximum cross-section of 1 mm².

13. The handheld power tool as described in claim 12, characterized in that, The second wiring arrangement (15) includes wires with a maximum cross-section of 0.5 mm².

14. The handheld power tool as described in claim 12, characterized in that, The second wiring arrangement (15) includes wires with a maximum cross-section of 0.33 mm².

15. The handheld power tool as described in claim 1 or 2, characterized in that, The drive power lines (16A, 16B) have a cross-sectional area between 1.5 mm² and 5 mm².

16. The handheld power tool as described in claim 1 or 2, characterized in that, The interference suppression capacitor (13) has a capacitance between 0.1 µF and 1 µF.

17. The handheld power tool as described in claim 1 or 2, characterized in that, The interference suppression capacitor (13) is designed as an X1 or X2 type capacitor.

Images