Electric hand tool with vibration-decoupled accumulator unit

Abstract

The invention relates to an electric hand tool with a handheld machine housing (1) for accommodating an electromechanical drive unit (2) for a tool holding unit (3), and with an accumulator unit (5) serving to supply electrical power to the drive unit (2), which is detachably attached to the machine housing (1) via a vibration-isolated connection interface (4), wherein the vibration-isolated connection interface (4) comprises spaced-apart retaining rail parts (6a, 6b) for the accumulator unit (5), which are attached to the machine housing (1) via at least one associated elastomer element (7; 7').

Description

[0001] The present invention relates to an electric hand tool with a machine housing for accommodating an electromechanical drive unit for a tool holding unit and with an accumulator unit for supplying electrical power to the drive unit, which is detachably attached to the machine housing via a vibration-decoupled connection interface.

[0002] The invention's application area extends primarily to handheld power tools, such as impact drills, chisels, rotary hammers, or combination hammers, which are subject to strong drive-related vibrations. These vibrations can damage the battery unit in battery-powered power tools. State of the art

[0003] US patent 2021 / 283758 AA discloses a generic electric hand tool with a vibration-damped connection interface for attaching a battery unit to the machine housing. Vibration damping is achieved by placing an elastomer buffer in front of the battery unit, which, however, can only provide limited vibration damping.

[0004] It is therefore the object of the present invention to further improve an electric hand tool with a vibration-decoupled connection interface for the detachable fastening of an accumulator unit in such a way that effective and space-saving vibration decoupling can be achieved. Disclosure of the invention

[0005] The problem is solved starting from an electric hand tool according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims describe advantageous embodiments of the invention.

[0006] The invention includes the technical teaching that a vibration-decoupled connection interface comprises spaced-apart retaining rail parts for the accumulator unit, which are attached to the rail housing via at least one associated elastomer element.

[0007] The advantage of the solution according to the invention lies particularly in the fact that it allows for a space-saving battery connection that is vibrationally decoupled from the rest of the power tool. This decoupling is preferably located on both sides of a mounting module that is directly attached to the mounting rail components and serves for the mechanical insertion and electrical contact of the battery unit. The mounting module, which serves for receiving, connecting, and contacting the battery unit, can be used universally for power tools with and without the vibration decoupling according to the invention. For this purpose, the mounting module is designed so that it can alternatively also be attached directly to the machine housing to provide a non-vibrationally decoupled version.Likewise, the universal receiving module can also be used in conjunction with the mounting rail elements described above according to the invention, namely to provide the vibration-decoupled solution according to the invention.

[0008] The retaining rail components according to the invention are preferably screwed or riveted to the universal mounting module and form a single unit within the vibration-isolated solution. It should be noted that the retaining rail components do not necessarily have to be designed as individual rod-shaped parts. Alternatively, the retaining rail components can also be part of a one-piece frame element, which may have a closed or open contour.

[0009] According to a preferred embodiment of the invention, it is proposed that each retaining rail section be assigned two elastomer elements, which are spaced apart from each other in the end region of the mounting rail on both sides. When two retaining rail sections are used, a total of four elastomer elements thus provide vibration decoupling of the accumulator unit from the machine housing, which vibrates due to the drive. Since the vibration transmission to the accumulator unit occurs via the elastomer elements, a spring-like and, due to the material properties, also a damping reduction of the vibrations takes place.

[0010] Preferably, the retaining rail components are made of an injection-molded plastic material and have integrated receiving elements for the elastomeric elements at both ends. This allows the receiving elements to be easily shaped to fit the elastomeric elements used.

[0011] According to a preferred embodiment, the receiving means of the retaining rail parts are designed as a type of receiving pocket, which serves to accommodate one associated elastomer element each. This allows the elastomer elements to be inserted into the associated receiving pockets, and the pocket shape holds them in the desired position, thus aiding assembly.

[0012] The mounting module is designed with modularity in mind, allowing it to be attached directly to a machine housing. This means the mounting module can be connected to the machine housing without mounting rails, for example, by screws. This results in a non-vibration-isolated connection using the mounting module as a standard component, which is suitable, for example, for low-power power tools or those without strong drive-related vibrations.

[0013] Within the framework of the vibration-isolated connection variant according to the invention, three-dimensional vibration decoupling can be achieved according to a further measure improving the invention by integrally forming a support pin with a distal dome section of smaller diameter on the machine housing, onto which a hollow cylindrical elastomer element is attached. This element is at least partially enclosed on its outer circumference by the retaining rail part, in particular its receiving pocket, and is fixed with a retaining screw screwed into the support pin. This results in a connection interface that is elastic in every spatial axis and thus particularly vibration-isolated.

[0014] As a further measure to improve this three-dimensional vibration decoupling, it is proposed that, in the unmounted state, the height of the dome section be smaller than the height of the hollow cylindrical elastomer element, allowing the elastomer element to be mounted under preload. The degree of preload can be adjusted via the height of the dome section or the thickness of the elastomer element. The elastomer element can thus be preloaded in a defined and consistent manner by means of the screw connection. The degree of preload alters the spring and damping properties of the elastomer element, thereby enabling optimal adaptation to the excitation vibration of the power tool. For power tools of the type of interest here, the height of the dome section is preferably 0.1 to 2 mm smaller than the height of the hollow cylindrical elastomer element mounted on it in order to achieve effective preload.

[0015] Another factor influencing optimal spring and damping properties is the elastomer material. Preferably, the elastomer element consists of an acrylonitrile butadiene rubber (NBR) or a hydrogenated nitrobutadiene rubber (HNBR) with a Shore hardness in the range of 30 to 90. In practice, lower hardness values ​​would impair the service life of the elastomer element, whereas higher hardness values ​​would prevent effective vibration decoupling. Detailed description based on drawing

[0016] Further measures improving the invention are described in more detail with reference to the figures, along with a description of preferred embodiments of the invention. The figures show: Fig. 1 a schematic side view of an electric hand tool with a vibration-isolated battery unit attached to it, Fig. 2 a perspective view from a low angle of the vibration-isolated connection interface of the electric hand tool on the housing side. Fig. 1 , Fig. 3 a perspective view of the top side of the component serving as a vibration-decoupled connection interface according to Fig. 2 , Fig. 4 a perspective view of the underside of the component serving as a vibration-decoupled connection interface according to Fig. 2 Fig. 5 shows a schematic longitudinal section through an exemplary connection point of the vibration-isolated connection interface, and Fig. 6 shows a perspective detail view of the connection point. Fig. 4 in a ready-to-install state.

[0017] According to Fig. 1An electric hand tool essentially consists of a handheld machine housing 1 made of plastic, in which an electromechanical drive unit 2 is housed. This drive unit 2 powers a tool holder 3 protruding from the machine housing 1, for the detachable attachment of a hammer drill or similar tool. An accumulator unit 5, detachably attached to the machine housing 1 via a vibration-damped connection interface 4, provides electrical power to the integrated drive unit 2.

[0018] According to Fig. 2To form a vibration-isolated connection interface 4, the retaining rail parts 6a and 6b, which are identical components, are arranged on both sides of a receiving module 8 attached thereto. The receiving module 8 serves for the mechanical insertion and electrical contacting of the accumulator unit 5 (not shown here). The receiving module 8 is fastened to the retaining rail parts 6a and 6b by means of several fastening screws 9 (exemplary). Several identical elastomer elements 7 provide vibration isolation from the machine housing 1.

[0019] As from Fig. 3As can be seen, two elastomer elements 7, 7' (exemplary) are provided for each retaining rail section 6a or 6b, which are spaced apart from each other in the end region on both sides of the respective retaining rail section 6a or 6b. The vibration-isolated connection interface thus provides a total of four connection points between the machine housing and the accumulator unit, each equipped with elastomer elements 7.

[0020] After Fig. 4 The retaining rail parts 6a and 6b are detachably fastened to the receiving module 8 via a total of six fastening screws 9. The retaining rail parts 6a and 6b have a Z-profile which is stabilized by several reinforcing ribs arranged longitudinally spaced apart from each other.

[0021] According to Fig. 5Three-dimensional vibration decoupling is achieved using the assembly described above, in that a support pin 10 is integrally formed on the machine housing side, which has a distal dome section 11 of smaller diameter. A hollow cylindrical elastomer element 7 is fitted onto the distal dome section 11 and fixed via a washer 12 and a retaining screw 13. The retaining screw 13 is screwed coaxially into the cylindrical support pin 10. The elastomer element is enclosed on its outer circumference by the retaining rail section 6a.

[0022] As from Fig. 6As can be seen, the exemplary elastomer element 7 is enclosed on the exemplary retaining rail part 6a by means of a receiving pocket 14, which is shaped to fit the geometry of the associated elastomer element 7 and is integrally formed on the retaining rail part 6a. With the retaining screw 13 unmounted, the elastomer element 7 can be inserted into the retaining pocket 14, which is then placed onto the housing-side support pin 10 and secured under preload with the retaining screw 13.

[0023] The solution according to 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 use fewer or more than two elastomer elements within the vibration-isolated connection interface. The desired properties of vibration decoupling can be individually adjusted for each device series by selecting the material of the elastomer element and the degree of preload. Furthermore, the solution according to the invention also offers the possibility of a non-vibration-isolated variant through the use of the receiving module. Reference symbol list

[0024] 1 Machine housing 2 Drive unit 3 Tool holder unit 4 Connection interface 5 Battery unit 6 Mounting rail section 7 Elastomer element 8 Mounting module 9 Mounting screw 10 Support pin 11 Dome section 12 Washer 13 Retaining screw 14 Mounting pocket

Claims

1. Electric hand tool with a handheld machine housing (1) for accommodating an electromechanical drive unit (2) for a tool holding unit (3), and with an accumulator unit (5) for supplying electrical power to the drive unit (2), which is detachably attached to the machine housing (1) via a vibration-isolated connection interface (4), characterized by the fact that the vibration-decoupled connection interface (4) comprises mutually spaced retaining rail parts (6a, 6b) for the accumulator unit (5), which are attached to the machine housing (1) via at least one associated elastomer element (7; 7').

2. Electric hand tool according to claim 1, characterized by the fact that the retaining rail parts (6a, 6b) are arranged on both sides of a receiving module (8) directly attached thereto for mechanical insertion and electrical contacting of the accumulator unit (5).

3. Electric hand tool according to claim 2, characterized by the fact thatthe retaining rail parts (6a, 6b) are screwed or riveted to the receiving module (8).

4. Electric hand tool according to one of the preceding claims, characterized by the fact that Each retaining rail part (6a; 6b) has two elastomer elements 7, 7') which are spaced apart from each other in the end region of the respective retaining rail part (6a; 6b).

5. Electric hand tool according to one of the preceding claims, characterized by the fact that the retaining rail parts (6a, 6b) are part of a one-piece frame element.

6. Electric hand tool according to one of the preceding claims, characterized by the fact that the retaining rail parts (6a; 6b) are made of an injection-molded plastic material and are provided with receiving means for the elastomer elements (7, 7') molded into the end area on both sides.

7. Electric hand tool according to one of claims 2 to 6, characterized by the fact thatthe receiving module (8) is designed in such a way that it can alternatively be attached directly to the machine housing (1) in order to provide a non-vibration-decoupled connection variant.

8. Electric hand tool according to one of the preceding claims, characterized by the fact that For three-dimensional vibration decoupling from the machine housing (1), a support pin (10) with a distal dome section (11) of smaller diameter is formed, onto which a hollow cylindrical elastomer element (7) is placed, which is enclosed at least partially on its outer circumference by the retaining rail part (6a; 6b) and is fixed with a retaining screw (13) screwed into the support pin (10).

9. Electric hand tool according to claim 8, characterized by the fact that In the unassembled state, the height of the dome section (11) is less than the height of the hollow cylindrical elastomer element (7), so that the elastomer element (7) is mounted under preload.

10. Electric hand tool according to claim 9, characterized by the fact that the height of the dome section (11) is 0.1 to 2 mm smaller than the height of the hollow cylindrical elastomer element (7).

11. Electric hand tool according to one of the preceding claims, characterized by the fact that the elastomeric element (7) consists of an NBR or HNBR material with a Shore hardness of 30 to 90.

12. Electric hand tool according to one of the preceding claims, characterized by the fact that the receiving means of the retaining rail part (6a; 6b) is equipped as receiving pockets (14) for accommodating each associated elastomer element (7).

13. Electric hand tool according to claim 12, characterized by the fact that Each receiving pocket (14) is opened from the front face of the retaining rail part (6a; 6b) to allow for the assembly / disassembly of an associated elastomer element (7; 7').

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