Hammer drill or chisel hammer having a vibration-decoupled device housing

Abstract

The invention relates to a hammer drill or chisel hammer having a device housing (1) for vibration-decoupled accommodation of an axial impact unit, comprising an impact mechanism (4) having a drive motor (3), for generating a linear alternating working movement, which can be transferred to a chisel tool via an end-mounted tool holder unit (5), wherein the axial impact unit is guided along the axial working movement direction via at least one frontal sliding guide (6) arranged in the region of the impact mechanism (4), and via at least one rear sliding guide (9a, 9b) arranged in the region of the drive motor (3), and is vibration-decoupled by at least one decoupling spring (10), which is also arranged between the device housing (1) and the axial impact unit and also acts in the working movement direction, wherein the rear sliding guide (9a, 9b) comprises at least one U-shaped profiled housing-mounted guide rail (11), in which at least one corresponding impact-unit-mounted guide block (12) is guided.

Description

[0001] Hilti Corporation

[0002] Principality of Liechtenstein

[0003] DRILL OR CHISEL HAMMER WITH A VIBRATION-DECOUPLED HOUSING

[0004] DESCRIPTION

[0005] The invention relates to a drilling or chiseling hammer with a device housing for the vibration-decoupled accommodation of an axial impact unit, comprising an impact mechanism provided with a drive motor for generating a linearly alternating working movement, which can be transmitted to a chisel tool via an end-side tool holder unit, wherein the axial impact unit is guided along the axial working movement direction via at least one front sliding guide arranged in the region of the impact mechanism and via at least one rear sliding guide arranged in the region of the drive motor and is vibration-decoupled by a decoupling spring arranged between the device housing and the axial impact unit, also acting in the direction of movement.

[0006] The field of application of the invention extends primarily to a handheld chipping hammer, which is preferably operated by an electric drive. A chipping hammer of the type in question here most preferably has a center of gravity located in the region of the impact mechanism axis. For this purpose, the components drive motor, gear, impact mechanism, and tool holder unit are arranged coaxially to the impact mechanism axis. In addition to an application in a chipping hammer, it is also conceivable to use the inventive solution in a hammer drill, in which a linearly alternating working movement is superimposed with a rotary movement for a percussion drill as a tool. State of the art

[0007] The generally known prior art discloses a chisel hammer of the type in question here, which is equipped with a so-called sub-chassis decoupling system for the vibration-decoupled axial impact unit housed in a tool housing. This sub-chassis decoupling system allows relative movement of the internal active component with respect to the surrounding tool housing in the direction of working movement. For this purpose, the vibration decoupling usually comprises a front sliding guide surrounding the impact mechanism and arranged axially adjacent to the external tool holder unit. A sliding sleeve arrangement, for example, can be used for this purpose. This front sliding guide interacts with a rear sliding guide, which is usually arranged at the level of the drive motor and there connects the axial impact unit to the surrounding tool housing.The sliding guide arrangement, consisting of the front and rear sliding guides, enables relative movement of the axial impact unit relative to the device housing over a stroke along the axial working direction. The sliding guide arrangement is completed by at least one decoupling spring, which also acts in the working direction and is arranged between the device housing and the impact mechanism and is usually designed as a leaf spring. The spring travel achievable in this way is quite limited due to the design and installation space. To achieve a permanently elastic function of the leaf spring over its service life, very high-quality spring steel is required. However, the leaf spring usually only partially acts as a spring in the direction of the impact axis. Its main function is to suspend the axial impact unit in the device housing.Therefore, an additional compression spring is usually required to achieve the required stiffness in the direction of the impact axis.

[0008] The object of the present invention is to further improve a rotary hammer or chisel hammer of the generic type so that reliable and effective vibration decoupling is achieved with minimal technical effort. Disclosure of the Invention

[0009] The problem is solved by a hammer drill or chisel hammer according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims represent advantageous developments of the inventive solution.

[0010] The invention includes the technical teaching that, in a rotary hammer or chisel hammer with a front and rear sliding guide, the rear sliding guide comprises at least one U-shaped profiled guide rail on the housing side, in which at least one corresponding guide block on the impact unit side is guided. According to a preferred embodiment, exactly one front sliding guide and two rear sliding guides are provided, which are arranged opposite one another laterally on the axial impact unit - preferably at drive height - in order to ensure reliable, permanent sliding guidance in the working direction of movement via a minimal number of guide points.

[0011] The advantage of the inventive solution lies in the fact that, thanks to the simple design of the guide elements, correspondingly simple production and assembly of the device housing or the impact mechanism is possible. Furthermore, the guide principle offers the structural prerequisite for the use of decoupling springs with long spring travel, preferably compression, conical, or barrel springs. This enables vibration decoupling with values ​​below 5 m / s. 2 achievable, as tests have shown. Such a decoupling spring-sliding guide combination allows for a relatively long stroke, thus achieving comfortable vibration decoupling. This makes it possible to design for an optimal stroke.

[0012] According to a measure further improving the invention, the guide block is provided with elastomer elements on both sides in the direction of movement, which interact with corresponding stop sections of the tool housing. This creates a gentle end stop on both sides when the maximum compression and rebound strokes are reached. With regard to the compression stroke, this buffered end stop prevents the spring coils of the decoupling spring from colliding with one another, which would lead to a harsh shock impulse and, in extreme cases, could damage the decoupling spring or adjacent components. In the normal state, in which the decoupling spring is rebounded, the front elastomer element comes into contact with the associated stop section of the tool housing under preload, in particular to allow easy removal of a jammed chisel tool.

[0013] According to a preferred embodiment of the guide block, which preferably has a T-shaped side view, a pin section is provided at its base area, allowing the guide block to be precisely inserted into a corresponding base bore of the axial impact unit. The inserted guide block can then be releasably fastened to the axial impact unit by means of a screw via a through-bore that preferably runs coaxially to the pin section. The through-bore for the screw connection is arranged on the T-shaped guide block in such a way that it does not obstruct the elastomer elements that are preferably inserted therein on both sides. Furthermore, a single, central screw connection is sufficient to reliably fasten the guide block.Furthermore, this central screw connection ensures a certain degree of pivoting of the guide block around its longitudinal axis, allowing the guide block to automatically align itself with the guide path defined by the guide rail. This prevents frictional wear on the guide block flanks, which would otherwise occur due to the guide block grinding into the guide rail. This would subsequently lead to an unwanted increase in guide play, which is easily prevented thanks to the central screw connection.

[0014] In contrast, the housing-side guide rail is preferably clipped or pressed into a corresponding device structure without the need for fasteners. For this purpose, the guide rail preferably has a flat insertion tab formed on the base section at at least one end of the rail, which engages with a corresponding retaining structure on the inside of the device housing. This easily prevents the guide rail from being captively mounted by clipping or pressing.

[0015] According to a preferred embodiment, the U-shaped profiled guide rail is manufactured as a stamped and bent metal part. It is preferably made of stainless steel to enable optimal sliding of the guide block as a friction partner. The guide block can be formed as an injection-molded part, for example, made of a PAG plastic.

[0016] Detailed description based on drawing

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

[0018] Fig. 1 shows a longitudinal section through a chisel hammer with a front and rear sliding guide for the vibration-decoupled accommodation of an axial impact unit,

[0019] Fig. 2 is a perspective view of a housing-side guide rail of the rear sliding guide, and

[0020] Fig. 3 is a perspective view of a guide block of the rear sliding guide on the impact unit side.

[0021] According to Fig. 1, a chisel hammer has a plastic housing 1 with a handle 2 molded onto the rear for manual handling of the tool. The housing 1 houses an axial impact unit comprising an electric drive motor 3 and a percussion mechanism 4 (known per se), which converts the rotary motion of the drive motor 3 into a linearly alternating working motion for a chisel tool (not shown here). For this purpose, a tool holder unit 5 is provided at the end of the percussion mechanism 4. The axial impact unit with drive motor 3, percussion mechanism 4, and tool holder unit 5 are arranged along the same percussion mechanism axis.

[0022] The internal axial impact unit is guided by a front sliding guide 6 arranged in the area of ​​the impact mechanism 4, which consists of an outer guide ring 7 on the housing side and an inner guide ring 8 on the impact unit side surrounded by the outer guide ring 7. This interacts with two rear sliding guides 9a and 9b arranged at the level of the drive motor 3, which are arranged opposite one another on the sides of the axial impact unit.

[0023] A decoupling spring 10, designed as a compression spring, is arranged between the device housing 1 in the area of ​​the handle and the proximal end of the axial impact unit—here specifically its drive motor 3. The decoupling spring 10 ensures vibration decoupling acting in the working direction, the stroke of which in the axial working direction is enabled by the sliding guide means described above.

[0024] The two rear sliding guides 9a and 9b are identically constructed and each consist of a housing-side guide rail 11, in which a corresponding impact unit-side guide block 12 is guided along the working movement direction. The guide block 12 is inserted into a recess in the drive motor 3 of the axial impact unit and secured by a screw 13. In contrast, the guide rail 11 is clipped into a corresponding housing structure of the device housing 1.

[0025] According to Fig. 2, the U-shaped profiled housing-side guide rail 11 has a flat insertion tab 15 formed on the end of the base section 14 for clipping into the corresponding housing structure of the device housing (not shown here). The U-shaped profiled guide rail 11 is manufactured as a stamped and bent part from a stainless steel sheet.

[0026] The guide block shown in Fig. 3, which corresponds to the friction partner

[0027] 12 has a T-shaped side view, the base area of ​​which is designed as a cylindrical pin section 16 in order to be inserted precisely into the above-mentioned corresponding recess on the axial impact unit.

[0028] In addition, the guide block 12 is provided with elastomer elements 17a and 17b on both sides of the leg area, which interact with the aforementioned stop sections on the device housing as an end stop. For reasons of clarity, the second elastomer element 17b is hidden.

[0029] Furthermore, the guide block 12 has a through-hole 18 running coaxially with the pin section 16 for implementing the screw connection described above. The through-hole 18 is a countersunk hole to conceal the screw connection using a hexagon socket screw or the like. The guide block 12 is also made of an injection-molded plastic material.

[0030] The invention is not limited to the preferred embodiment described above. Rather, modifications thereof are also conceivable, which are also encompassed by the scope of the following claims. For example, the solution according to the invention can also be used in a hammer drill. Furthermore, the design of the decoupling spring is not limited solely to a steel compression spring. Elastomer springs, air springs, or the like can also be used for this purpose.

[0031] List of reference symbols

[0032] 1 device housing

[0033] 2 handle

[0034] 3 Drive motor

[0035] 4 percussion

[0036] 5 Tool holder unit

[0037] 6 front sliding guide

[0038] 7 outer sliding sleeve

[0039] 8 inner sliding sleeve

[0040] 9 rear sliding guide

[0041] 10 Decoupling spring

[0042] 11 Guide rail

[0043] 12 Guide block

[0044] 13 Screw

[0045] 14 floor section

[0046] 15 tuck-in flap

[0047] 16 tenon section

[0048] 17 Elastomer element

[0049] 18 through hole

Claims

CLAIMS 1. A rotary hammer or chisel hammer with a tool housing (1) for vibration-decoupled accommodation of an axial impact unit, comprising a percussion mechanism (4) provided with a drive motor (3) for generating a linearly alternating working movement, which can be transmitted to a chisel tool via an end-mounted tool holder unit (5), wherein the axial impact unit is guided along the axial working movement direction via at least one front sliding guide (6) arranged in the region of the percussion mechanism (4) and via at least one rear sliding guide (9a, 9b) arranged in the region of the drive motor (3), and is vibration-decoupled by at least one decoupling spring (10) arranged between the tool housing (1) and the axial impact unit, also acting in the working movement direction, characterized in that the rear sliding guide (9a, 9b) comprises at least one U-shaped profiled guide rail (11) on the housing side,in which at least one corresponding impact unit-side guide block (12) is guided., 2. Drill or chisel hammer according to claim 1, characterized in that the guide block (12) is provided with end-side elastomer elements (17a, 17b) which interact with corresponding stop sections of the device housing (1).

3. Drill or chisel hammer according to claim 1 or 2, characterized in that the guide block (12) is inserted with a rear pin portion (16) into a corresponding recess of the axial impact unit.

4. Drill or chisel hammer according to claim 3, characterized in that the inserted guide block (12) is fastened to the axial impact unit by means of a screw (13) via a through-bore (18) running coaxially to the pin section (16).

5. Drill or chisel hammer according to one of the preceding claims, characterized in that the housing-side guide rail (11) is clipped or pressed into a corresponding housing structure of the device housing (1) without any fastening means.

6. Drill or chisel hammer according to one of the preceding claims, characterized in that the guide rail (11) is provided at at least one rail end with a flat insertion tab (15) formed on the end of the base section (14).

7. Drill or chisel hammer according to one of the preceding claims, characterized in that the U-shaped profiled guide rail (11) is designed as a metallic stamped and bent part.

8. Drill or chisel hammer according to one of the preceding claims, characterized in that the guide block (12) is designed as a plastic injection-molded part.

9. Drill or chisel hammer according to one of the preceding claims, characterized in that the axial impact unit with drive motor (3), impact mechanism (4) and tool holder unit (5) are arranged along the same impact mechanism axis.

10. Drill or chisel hammer according to one of the preceding claims, characterized in that exactly one front sliding guide (6) and two rear sliding guides (9a, 9b) are provided, which are arranged opposite one another laterally on the axial impact unit.

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