EP4620623A1

EP4620623A1 - Electric tool

Info

Publication number: EP4620623A1
Application number: EP24164141.4A
Authority: EP
Inventors: Thomas Kiontke; Cora Hobelsberger; Marcus JENKE; Stephan Mayer; Christoph Winkler; Sebastian Spiegler
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2024-03-18
Filing date: 2024-03-18
Publication date: 2025-09-24
Also published as: WO2025195773A1

Abstract

An electric tool, comprising a tool housing (21).a motor (3) having a rotating shaft (2), a motor housing (4) accommodating the motor (3), a gearbox (6) arranged at a front side of the motor (3), a main shaft (5) supported by the gearbox (6) and extending in a direction intersecting the rotating shaft (2), a circuit board (10) mounted in the motor housing (4) and located substantially above the motor (3), a battery accommodating part (8) mounted behind the motor housing (4) and used to accommodate a rechargeable battery (7), and a handle (9) mounted behind the battery accommodating part. The electric tool of the present invention has an optimized, balanced tool structure and is more ergonomic, facilitating user operation.

Description

TECHNICAL FIELD

The present invention relates to an electric tool, in particular a rechargeable electric tool for grinding workpiece materials, which grinds workpieces by making a top end tool rotate.

BACKGROUND ART

In the prior art, handheld electric tools for performing grinding work, such as angle grinders, generally have an electric motor installed in a tool housing to act as a source of driving power. A handle part for the person carrying out the work to grip is formed on the housing behind the electric motor. A gear transmission mechanism is arranged at a front part of the tool, while a detachable rechargeable battery is fitted at a rear part of the handle part to act as a power supply. The handle part is often constructed in the form of a tube, so that the user can grip it easily, and the battery is fitted at the rear part of the handle; as the demand for large-capacity batteries grows, battery size and weight are also increasing, but the weight of the battery will result in the centre of gravity of the electric tool being displaced from the optimal balanced position. Furthermore, when the user grips the handle, his arm might interfere with the battery. In addition, when the battery is fitted at the rear part of the handle, a circuit board is also often arranged close to the battery behind the handle, resulting in increased length and complex arrangement of electric wires connecting the motor to the circuit board.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide an electric tool which has an optimized, balanced tool structure and is more ergonomic, to facilitate user operation.
The present invention provides an electric tool comprising a tool housing, a motor having a rotating shaft, a motor housing accommodating the motor, a gearbox arranged at a front side of the motor, a main shaft supported by the gearbox and extending in a direction intersecting the rotating shaft. A battery accommodating part is mounted behind the motor housing and used to accommodate a rechargeable battery. A handle is mounted behind the battery accommodating part. In the electric tool of the present invention, the battery is mounted between the motor and the handle, thus optimizing the balance of the overall structure of the electric tool and avoiding interference between a user's hand and the battery, so the electric tool has better ergonomics. The battery accommodating part is assembled to the motor housing, thus the drive unit and wirings can be preassembled together, and the battery accommodating part can be replaced without removing the drive apparatus, so repairing is convenient.
The electric tool further comprises a circuit board received in the tool housing and located adjacent to the motor housing. At least one air inlet is formed on the outer surface of the tool housing. With the circuit board mounted in the tool housing and located adjacent to the motor housing, an electric tool drive unit can be pre-assembled, and wires connecting the motor and the circuit board are very short, avoiding wiring complexity and possibly generated heat to a very large extent due to wiring losses.
According to a preferred embodiment, the circuit board is located parallel to the rotating shaft of the motor and the air inlet is positioned opposite to the circuit board. Hence, external air flows past the circuit board along the most direct path, avoiding overheating of electronic devices on the circuit board to the maximum extent possible.
More preferably, the circuit board is located above the motor housing and the air inlet is formed on the tool housing above the circuit board. Thus, the wires connecting the motor and the circuit board would be shortest and the cooling path would be optimized.
A fan is provided at a front end of the motor, and at least one air outlet is formed on the gearbox in front of the fan. Thus, a cooling airflow is sucked in through the air inlet formed on the tool housing, flows past the circuit board, and flows downward and rearward to a region behind the motor; the action of the fan then causes the cooling airflow to flow past the motor from behind the motor and be discharged from the outlet on the gearbox at the front side of the motor. Thus, an optimized flow path for the cooling airflow is formed, greatly improving heat dissipation from the electric tool.
According to another embodiment of the present invention, a side of the battery accommodating part close to the motor housing is provided with a battery mounting part, and the battery is removably attached to the battery mounting part. The battery mounting part is close to a side of the motor housing so that the wires connecting the battery and the circuit board are shorter, helping to simplify the layout of wires and avoid generating an excessive amount of heat.
According to a preferred embodiment of the present invention, when the battery is mounted to the battery accommodating part by a mounting direction substantially parallel to the direction of extension of the main shaft. Thus, during use of the electric tool, the battery suffers little interference; during cutting especially, it is undesirable for the battery accommodating part to strike the ground. In addition, when the battery is mounted parallel to the direction of extension of the main shaft, insertion and withdrawal are easier in this direction.
The battery accommodating part is substantially in the form of a cavity having an opening that is open in an upward direction, and two sides of the cavity comprise battery protection parts extending substantially along the longitudinal length of the battery. This not only makes mounting and removal of the battery convenient, but also ensures that the battery will not be damaged easily after being mounted to the electric tool, even if the electric tool is accidentally dropped.
The battery comprises an unlock button for releasing the battery from the battery mounting part, the unlock button being at a higher position than the motor housing when the battery is mounted to the battery accommodating part, so that the battery can be easily withdrawn from the battery mounting part.
According to another embodiment of the present invention, the handle is rotatable, and a front end of the handle is connected to the rear of the battery accommodating part via a rotation mechanism. The rotatable handle helps the user to grip the tool better in various application scenarios.
The handle is substantially in the form of a D shape extending in a front-rear direction.
The D-shaped handle helps the user to grip the tool conveniently and reliably, and also helps to balance the overall structure of the electric tool.
The handle rotates about a rotation axis X parallel to the direction of extension of the rotating shaft.
The rotation mechanism has a locking part for locking a rotation angle, and the handle has at least three locking positions at -90 degrees, 0 degrees and 90 degrees relative to the rotation axis X thereof. It is extremely important that the handle can be kept in a locked state after rotating to the desired angle, to ensure that undesired rotation or shifting of the electric tool will not occur during operation. In addition to grinding applications in which a planar region of an abrasive disc is used to grind a surface of a material being processed, the electric tool is s also used for cutting applications in which a peripheral surface region of an abrasive or diamond disc is used to cut a material being processed. Thus, when changing the form of applications, the direction of the rotation axis of the abrasive disc relative to the material being processed will be changed by roughly 90 degrees. Thus, the handle of the electric tool of the present invention can rotate through 90 degrees, so is conveniently suitable for grinding applications or cutting applications.
According to an embodiment of the present invention, the electric tool is a grinding tool, in particular an angle grinder.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the embodiments mentioned can be gained from the following detailed description with reference to the drawings. It is emphasized that the various components are not necessarily drawn to scale. In fact, dimensions may be increased or decreased at will for the purpose of clear description. In the drawings, identical reference numerals denote identical elements.

Fig. 1: is a side view of an angle grinder in an example of the electric tool of the present invention.
Fig. 2: is a side view of the electric tool of the present invention shown in Fig. 1, with part of a tool housing removed.
Fig. 3: is a top view of the electric tool of the present invention shown in Fig. 1.
Fig. 4: is a sectional view in the Z-Z direction of the electric tool of the present invention shown in Fig. 3.

DETAILED DESCRIPTION OF THE INVENTION

The following description is merely exemplary and does not limit the disclosure of the present application and the application or purpose of the present invention. The terms "front", "rear", "above", "below", "left" and "right" in the present invention are used throughout this description to define various parts of the power tool when provided in an orientation in which it is desired to be used, such as the orientation shown in Fig. 1.
According to an embodiment of the present invention, as an example of an electric tool, an angle grinder is used for illustration.
As shown in Fig. 1, an electric tool 1 comprises a tool housing 21, and a motor 3 as a source of driving power. Inside the tool housing 21, there is a motor housing 4 for accommodating the motor 3. The motor 3 has a rotating shaft 2 extending substantially in the front-rear direction of a tool main body; this rotating shaft 2 is an output shaft of the motor 3. A front side of the motor 4 is connected to a gearbox 6, within which gearbox 6 is comprised a gear transmission mechanism connected to a front end of the rotating shaft 2. The gearbox 6 supports a main shaft 5 extending in a direction intersecting the rotating shaft 2, i.e. the main shaft 5 extends substantially in the vertical direction shown in Fig. 1, and is rotatable about its direction of extension. Thus, the high-speed rotational driving action of the motor 3 is outputted to the main shaft 5 after undergoing direction change and speed reduction via the rotating shaft 2 and the gear mechanism.
A grinding disc 20 formed as a round plate may be mounted on the main shaft 5 as a top end tool (rotating tool), for use in grinding application, etc. to level the surface of concrete or stone, metal, and other unhazardous materials which can be ground or cut. The mounted top end tool is not limited to an abrasive disc or a diamond disc for grinding in the form of a round plate; it is also possible to mount an abrasive disc or a diamond disc for cutting, a cutter or a brush in the form of a round plate, etc.
According to an embodiment of the present invention, a circuit board 10 is mounted in the tool housing 21 and is located adjacent to motor housing 4. In this way, the wiring between the circuit board 10 and the motor 3 will be very short, greatly reducing the complexity of arrangement of the wires. the wiring is a source of heat inside the tool, so shortened wiring will also help to reduce losses and the amount of heat generated by the electric tool during operation. In addition, as a drive unit, the motor 3 may be fitted to a complete circuit in advance - this is an electrically complete unit, which is easy to handle.
Preferably, the circuit board 10 is located parallel to the rotating shaft 2 of the motor. More preferably, the circuit board 10 is located above the motor housing 4. Thus, external air flows past the circuit board along the most direct path, avoiding overheating of electronic devices on the circuit board to the maximum extent possible. the wires connecting the motor and the circuit board would be shortest and the cooling path would be optimized.
The electric tool 1 further comprises a battery accommodating part 8, which is mounted behind the motor housing 4 and used to accommodate a rechargeable battery 7. Preferably, the battery accommodating part 8 and the motor housing 4 are separate components, i.e. the battery accommodating part 8 and the motor housing 4 are not integrally formed. Thus, in addition to the fact that the abovementioned drive unit can be pre-assembled, it is also possible to replace or overhaul components in the battery accommodating part without removing the drive apparatus, so overhaul is facilitated.
Referring to Figs. 2 and 3, the battery accommodating part 8 is composed of a left housing and a right housing, which are fixedly connected to left and right sides of the motor housing 4 respectively, for example by screws. The left and right housing are substantially in the form of two symmetrical [ shapes, fitted together to form a substantially square cavity 15 having an opening that is open in an upward direction. The bottom of the cavity 15 may be closed, semi-closed, or open.
A front side of the battery accommodating part 8 close to the motor housing 4 is provided with a battery mounting part 14, and the battery 7 is removably attached to the battery mounting part 14. The battery mounting part 14 is close to a side of the motor housing 4 so that the wires connecting the battery 7 and the circuit board 10 are shorter, helping to simplify the layout of wires and avoid generating heat. The battery mounting part 10 provided at the front side of the battery accommodating part 8 is substantially in the form of a flat plate which is rectangular and projects mainly towards the rear. As shown in Figs. 3 and 4, two mounting guide grooves are provided on a rear surface of the battery mounting part 10, the two battery mounting guide grooves being configured in a left/right arrangement. The battery 7 is a lithium ion battery with multiple cells accommodated in a hexahedral case. One of the longitudinal faces of the battery 7 extending along its length is a mounting face thereof, and two mounting guide rails are provided on the mounting face, such that the battery 7 is removably mounted to the battery mounting part 14 by sliding.
As described above, the battery accommodating part 8 is substantially in the form of a cavity 15 having an opening that is open in an upward direction; the battery has only one longitudinal mounting face of the hexahedron connected inside the cavity 15, while a longitudinal face opposite the mounting face faces towards a rear sidewall of the cavity, with a gap between itself and the rear sidewall. Left and right sides of the cavity 15 respectively comprise battery protection parts 16 extending substantially along the longitudinal length of the battery. Preferably, the battery protection part 16 comprises an upper part and a lower part, which respectively cover parts of the battery 7 which extend vertically beyond the motor housing 4 when the battery is mounted in the battery accommodating part 8. A heavy-duty angle grinder according to a schematic embodiment of the present invention often needs to be paired with a high-powered rechargeable battery; the battery 7 has a large size, with at least the longitudinal length thereof being larger than the size of a commonly used motor. For this reason, the battery protection parts 16 are provided at the left and right sides of the battery accommodating part 8; this not only guarantees convenience of mounting and removal of the battery, but also ensures that the battery will not be damaged easily after being mounted to the electric tool, even if the electric tool 1 is accidentally dropped or knocked.
The battery 7 comprises an unlock button 17, for releasing the battery 8 from the battery mounting part 14. The unlock button 17 is arranged on the longitudinal mounting face of the battery 7, and the position thereof is higher than the motor housing 4 when the battery 7 is mounted to the battery accommodating part 8. By sliding the battery 7 upwards in a state of having performed a pressing operation on the unlock button 17, the battery 7 can be removed from the battery mounting part 14. The battery 7 can be charged for repeated use by using a separately prepared charger.
According to a preferred embodiment of the present invention, the mounting direction of the battery 7 is substantially perpendicular to the direction of extension of the rotating shaft, thus helping to balance the centre of gravity of the electric tool, and making the battery exchange most convenient. More preferably, when the battery 7 is mounted to the battery accommodating part 8, the longitudinal direction thereof is substantially parallel to the direction of extension of the main shaft. During use of the electric tool 1, there is little interference with battery. Especially during cutting, it is undesirable for the battery accommodating part to strike the ground, and if the battery is arranged obliquely, a bottom end thereof will contact the ground to an even greater extent. In addition, when the battery is mounted parallel to the direction of extension of the main shaft, insertion and withdrawal are easier in this direction.
Referring to Figs. 1 - 4, at least one air inlet 11 is formed on the tool housing 21 above the circuit board 10. A front end of the motor 3 is provided with a fan 12, and at least one air outlet 13 is formed on the gearbox in front of the fan 12. When rotating, the fan 12 forms negative pressure, so external air is sucked in via the air inlet 11. The air inlet 11 is arranged above the circuit board, so external air flows past the circuit board along the most direct path, ensuring cooling of electronic devices on the circuit board to the maximum extent possible. As shown in Fig. 4, after being sucked in through the air inlet 11 on the top of the tool housing 21, a cooling airflow flows past the circuit board 10, and flows downward and rearward to a region behind the motor 3; the action of the fan then causes the cooling airflow to flow past the motor 3 from behind the motor and be discharged from the air outlet 13 on the gearbox at the front side of the motor. Thus, an optimized flow path for the cooling airflow is formed, greatly improving heat dissipation from the electric tool 1.
According to an embodiment of the present invention, a handle 9 is mounted behind the battery accommodating part 8. In the electric tool of the present invention, the battery 7 is mounted between the motor 3 and the handle 9, thus optimizing the balance of the overall structure of the electric tool, and avoiding interference between a user's hand and the battery, so the electric tool has better ergonomics. In the present invention, the handle 9 is also mounted and connected to the battery accommodating part; thus, the handle, the battery accommodating part and the drive unit are all independent components, not integrally formed. The process of manufacturing and shaping the electric tool becomes simple and easy to implement. With regard to the motor design of the present invention, the motor housing is a single-piece cylinder, and it is not advisable for the motor housing to be split in the middle; therefore, the motor housing must be released from its mould in the length direction thereof. If the battery accommodating part and the handle were integrally formed with the motor housing, it would be very complicated to release the battery accommodating part from its mould in the same direction. Furthermore, the work of mounting the wiring and the battery mounting part would also become complex, and the ability to overhaul the battery accommodating part would be lost.
According to a preferred embodiment of the present invention, the handle 9 is substantially in the form of a D shape extending in the front-rear direction. The D-shaped handle helps the user to grip the tool conveniently and reliably, and also helps to balance the overall structure of the electric tool. More preferably, the handle is rotatable. A front end of the handle is connected to the rear of the battery accommodating part 8 via a rotation mechanism 18. In addition to grinding applications in which a planar region of an abrasive disc is used to grind a surface of a material being processed, the electric tool is also used for cutting applications in which a peripheral surface region of an abrasive or diamond disc is used to cut a material being processed, and the rotatable handle helps the user to grip the tool better in various application scenarios.
Referring to Figs. 2 and 4, the handle 9 rotates about a rotation axis X parallel to the direction of extension of the rotating shaft. The rotation mechanism 18 has a locking part 19 for locking a rotation angle, and the handle 9 has at least three locking positions at - 90 degrees, 0 degrees and 90 degrees relative to the rotation axis X thereof. When changing the form of application, the direction of the rotation axis of the abrasive disc relative to the material being processed will be changed by roughly 90 degrees. Thus, the handle of the electric tool of the present invention can rotate through 90 degrees, so is conveniently suitable for grinding applications or cutting applications. The handle 9 can rotate 90 degrees to the left or right separately about the rotation axis X, so is more friendly to users accustomed to operating electric tools with the left hand. It is also extremely important that the handle can be kept in a locked state after rotating to the desired angle, to ensure that undesired rotation or shifting of the electric tool will not occur during operation.
The present invention is not limited to an angle grinder, and may be applied to various electric tools having a main output shaft intersecting the direction of extension of a tool main body, especially grinding tools that grind a workpiece by making a top end tool rotate, e.g. a polisher, etc. In addition, other structures of angle grinders are not limited to the arrangement described above. For example, the motor is not limited to a brushless motor. Furthermore, multiple battery packs (batteries) may also be used as a power supply.
As stated above, although exemplary embodiments of the present invention have been explained herein with reference to the drawings, the present invention is not limited to the specific embodiments described above, and may have many other embodiments. The scope of the present invention should be defined by the claims and their equivalents.

Claims

Electric tool (1), comprising a tool housing (21), a motor (3) having a rotating shaft (2), a motor housing (4) accommodating the motor (3), a gearbox (6) arranged at a front side of the motor (3), and a main shaft (5) supported by the gearbox (6) and extending in a direction intersecting the rotating shaft (2), characterized in that
a battery accommodating part (8) mounted behind the motor housing (4) and used to accommodate a rechargeable battery (7), and a handle (9) mounted behind the battery accommodating part.
Electric tool (1) according to Claim 1, characterized in that
the electric tool (1) further comprises a circuit board (10) received in the tool housing (21) and located adjacent to the motor housing (4), and at least one air inlet (11) is formed on the outer surface of the tool housing (20).
Electric tool (1) according to Claim 2, characterized in that
the circuit board (10) is located parallel to the rotating shaft (2) of the motor (3) and the air inlet (11) is positioned opposite to the circuit board (10).
Electric tool (1) according to Claim 3, characterized in that
the circuit board (10) is located above the motor housing (4) and the air inlet (11) is formed on the tool housing above the circuit board (10).
Electric tool (1) according to Claim 4, characterized in that
a fan (12) is provided at a front end of the motor (3), and an air outlet (13) is formed on the gearbox (6) in front of the fan (12).
Electric tool (1) according to any one of Claims 1 to 5, characterized in that
a side of the battery accommodating part (8) close to the motor housing (4) is provided with a battery mounting part (14), and the battery (7) is removably attached to the battery mounting part (14).
Electric tool (1) according to Claim 6, characterized in that
the battery (7) is mounted to the battery accommodating part (8) by a mounting direction substantially traverse to the rotating shaft (2).
Electric tool (1) according to Claim 6, characterized in that the battery accommodating part (8) is substantially in the form of a cavity (15) having an opening that is open in an upward direction, and two sides of the cavity (15) comprise battery protection parts (16) extending substantially along the longitudinal length of the battery (7).
Electric tool (1) according to Claim 6, characterized in that
the battery comprises an unlock button (17) for releasing the battery from the battery mounting part, the unlock button (17) being at a higher position than the motor housing (4) when the battery (7) is mounted to the battery accommodating part (8).
Electric tool (1) according to any one of Claims 1 - 9, characterized in that
the handle (9) is rotatable, and a front end of the handle (9) is connected to the rear of the battery accommodating part via a rotation mechanism (18).
Electric tool (1) according to Claim 10, characterized in that
the handle is substantially in the form of a D shape extending in a front-rear direction.
Electric tool (1) according to Claim 10, characterized in that
the handle (9) rotates about a rotation axis (X) parallel to the direction of extension of the rotating shaft (2).
Electric tool (1) according to Claim 10, characterized in that
the rotation mechanism (18) has a locking part (19) for locking a rotation angle, and the handle has at least three locking positions at -90 degrees, 0 degrees and 90 degrees relative to the rotation axis X thereof.
Electric tool (1) according to any one of the preceding claims, characterized in that the electric tool (1) is a grinding tool, in particular an angle grinder.