Battery-operated power tool comprising a plurality of rechargeable battery units

Abstract

The invention relates to a battery-operated electric power tool comprising two handle portions (2a, 2b) which are arranged opposite one another on a machine housing (1) and each of which is assigned a rechargeable battery unit (3a, 3b) which is detachably fastened thereto, wherein the two rechargeable battery units (3a, 3b) are electrically connected to one another in series and are connected to control electronics accommodated in the machine housing (1) via electrical conductors (4a, 4b), wherein the electrical series connection of the two rechargeable battery units (3a, 3b) is realised by means of a printed circuit board (5) outside the electrical conductors (4a, 4b).

Description

[0001] 2024P00022EP Hilti Aktiengesellschaft

[0002] Principality of Liechtenstein

[0003] Battery-powered power tool with multiple accumulator units

[0004] DESCRIPTION

[0005] The present invention relates to a battery-operated power tool with two handle sections arranged opposite each other on a machine housing, each of which is assigned a detachably attached accumulator unit, wherein the two accumulator units are electrically connected in series and are connected to a control electronics housed in the machine housing via electrical lines.

[0006] The application of the invention extends primarily to particularly powerful power tools in which at least two separate battery units are electrically connected in series to minimize current draw and maximize operating time. This allows battery units of a power tool system to be used individually for smaller power tools without the need for special custom-made components and matching chargers. The solution according to the invention is particularly applicable to power tools in which each battery unit is assigned to opposing handle sections arranged on a machine housing, for example, demolition hammers and the like.

[0007] US Patent 2023 / 0027574 describes a generic power tool designed as a demolition hammer with a vertical working axis. Handle sections are arranged on both sides of the machine housing, each with a battery unit located beneath it. The two battery units can be inserted into corresponding slots molded directly onto the machine housing. Internal electrical wiring runs through electrical contacts integrated into the slots to control electronics, also integrated into the machine housing, which primarily control the motor. The control electronics are located in the head of the power tool and can be operated via externally located electrical switches.

[0008] The object of the present invention is to further improve a battery-operated power tool of the generic type in such a way that an ergonomic arrangement of the accumulator units on the machine housing with simple cable routing and wiring is possible.

[0009] Summary of the invention

[0010] The problem is solved starting from a battery-operated power tool according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims describe advantageous embodiments of the invention.

[0011] The invention includes the technical teaching that an electrical series connection of both accumulator units of the power tool is made with a circuit board and thus outside the electrical lines.

[0012] The advantage of the solution according to the invention lies particularly in the fact that the electrical series connection is easier to manufacture, since the at least two-pole power line coming from each accumulator unit, as well as optional signal lines leading to the accumulator unit, which serve, for example, for communication between the device electronics and the respective accumulator unit, are not wired together, but rather via an intermediate circuit board, preferably placed centrally between the accumulator units in the machine housing, which is part of the control electronics. The solution according to the invention is easy to assemble. A separate cable harness can lead to each interface of the accumulator units, and the cable harnesses can be identical.

[0013] By positioning the cable harnesses appropriately, movements occurring during device operation are advantageously minimized. Furthermore, this can reduce cable bending caused, for example, by vibrations during operation, and thus the risk of damage to the respective cable harness, such as a cable break.

[0014] Preferably, the motor electronics for controlling a DC electric motor are also located on the circuit board of the series connection of the two battery units. However, it is also possible to have a separate circuit board for the motor electronics, which is located downstream of the separate circuit board of the series connection and is supplied with electrical current for operating the electric motors by the latter. Such a configuration allows the motor electronics to be positioned outside the shortest possible path between the two battery units. Short electrical leads minimize transmission losses.By using a circuit board separate from the motor electronics, a standardized platform motor electronics can be used for different devices, so that only the circuit board for the series connection of the battery units and the lines to the battery units need to be designed specifically for each device.

[0015] According to a further improvement of the invention, it is proposed that an electronic circuit be arranged on the circuit board of the series connection, which controls the discharge of the accumulator units in such a way that they are discharged simultaneously, regardless of an initial state of charge. Although the two accumulator units have different initial states of charge, they are discharged simultaneously to maintain a continuous power supply. This advantageously improves or maximizes the operating time of the accumulator units.

[0016] According to another improvement of the invention, it is proposed that the electrical conductors run at least partially within cable channels surrounding them, which are attached to the respective handle sections. The attachment is preferably by means of screws. The cable channels, in particular, prevent the insulation of the electrical conductors from abrasion due to vibrations within the machine. According to another improvement of the invention, it is proposed that the electrical conductors be provided with intermediate connectors in the area of ​​the handle sections. For example, the receiving interface of the accumulator units can be formed integrally with the handle brackets, and the plug connection arranged thereon facilitates the assembly of the electrical conductors.

[0017] Further measures improving the invention are described in more detail below, together with a description of a preferred embodiment of the invention, with reference to the figures. The figures show:

[0018] Fig. 1 shows a partially cutaway side view of a battery-operated power tool designed as a demolition hammer, and

[0019] Fig. 2 shows a perspective partial sectional view of the electrical wiring of the battery units of the power tool according to Fig. 1.

[0020] According to Fig. 1, a battery-operated power tool designed as a demolition hammer has two handle sections 2a and 2b arranged opposite each other on a machine housing 1, spaced apart from one another. The two handle sections 2a and 2b comprise handles that are pivotably mounted on the machine housing 1 to ensure vibration decoupling and protection against vibration damage to the user, as well as for the attached battery unit 3a and 3b, respectively. In contrast, control electronics associated with an integrated electric motor (not shown here) are housed within the machine housing 1. The two battery units 3a and 3b are electrically connected in series via electrical lines 4a and 4b, respectively, and are connected to the control electronics.As can be seen by way of example in the course of the electrical lines 4b, these run directly over a pivot axis S of the associated pivotable handle section 2b.

[0021] As can be seen in Fig. 2, the electrical series connection of the two accumulator units 3a and 3b is implemented with a printed circuit board 5, which is arranged outside the electrical conductors 4a and 4b, respectively. Separately from the printed circuit board 5 for establishing the series connection of the two accumulator units 3a and 3b, the motor electronics 6 for controlling the electric motors are integrated in an electronics housing.

[0022] To protect against damage, the electrical cables 4a and 4b run partially within surrounding cable ducts 7a and 7b, respectively. The cable ducts 7a and 7b are detachably attached to their respective handle sections (not shown here) by means of screws.

[0023] In the area of ​​the handle sections, the electrical lines 4a and 4b are connected to the accumulator units 3a and 3b respectively via their respective intermediate connectors 8a and 8b.

[0024] 3b connected.

[0025] The electrical lines 4a and 4b are joined to form a cable bundle which, in addition to a two-pole power supply line for the transmission of direct current from the accumulator unit 4a and 4b to the circuit board 5, also includes various signal lines for the signal connection between motor electronics and the respective electronics of the accumulator units 4a, 4b.

[0026] The invention is not limited to the preferred embodiment described above. Rather, variations thereof are also conceivable, which are also covered by the scope of protection of the following claims. For example, it is also possible to apply the solution according to the invention to other power tools with at least two battery units, which, for example, are arranged far apart from each other for ergonomic reasons. Reference numerals

[0027] 1 machine housing

[0028] 2 Handle section

[0029] 3 Accumulator unit

[0030] 4 electrical lines

[0031] 5 circuit board

[0032] 6 Motor electronics

[0033] 7 cable duct

[0034] 8 intermediate connectors

Claims

REQUIREMENTS 1. Battery-operated power tool with two handle sections (2a, 2b) arranged opposite each other on a machine housing (1), each of which is assigned a detachably attached accumulator unit (3a, 3b), wherein the two accumulator units (3a, 3b) are electrically connected in series and are connected to a control electronics housed in the machine housing (1) via electrical lines (4a, 4b), characterized in that the electrical series connection of the two accumulator units (3a, 3b) is realized with a circuit board (5) outside the electrical lines (4a, 4b).

2. Power tool according to claim 1, characterized in that the motor electronics (6) are integrated on the circuit board (5) of the series connection of the two accumulator units (3a, 3b).

3. Power tool according to claim 1 , characterized in that a separate circuit board for the motor electronics (6) is provided, which is downstream of the also separate circuit board (5) of the series circuit and is supplied with electrical current by it.

4. Power tool according to one of the preceding claims, characterized in that an electronic circuit is also arranged on the circuit board (5) of the series circuit, which controls the discharge of the accumulator units (3a, 3b) in such a way that they are discharged simultaneously regardless of an initial state of charge.

5. Power tool according to claim 1 , characterized in that each accumulator unit (3a, 3b) is detachably arranged below the handle sections (2a, 2b) of the machine housing (1).

6. Power tool according to claim 5, characterized in that it is designed as a demolition hammer with a vertical working axis (A).

7. Power tool according to claim 5 or 6, characterized in that the electrical lines (4a, 4b) from the accumulator units (3a, 3b) to the at least one circuit board (5) run directly over a pivot axis (S) of the pivotable handle sections (2a, 2b).

8. Power tool according to one of the preceding claims, characterized in that the electrical conductors (4a, 4b) run at least partially within cable ducts (7a, 7b) surrounding them, which are attached to the respective associated handle sections (2a, 2b).

9. Power tool according to one of the preceding claims, characterized in that the electrical lines (4a, 4b) in the area of ​​the handle sections (2a, 2b) are provided with intermediate connectors (8a, 8b).

10. Power tool according to one of the preceding claims, characterized in that the electrical lines (4a, 4b) are power supply and / or signal lines.

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