Power tool with cable strain relief

Abstract

Power tool (10) with at least two housing parts (12, 14), with a cable strain relief comprising a first clamping part (36) and a cooperating second clamping part (38) for clamping a connecting cable (18) between the two clamping parts (36, 38), wherein the first clamping part (36) has means (30) for fixing it in a first housing part (12) of the power tool (10) and the second clamping part (38) is connectable to the first clamping part (36) or the first housing part (12) to fix the connecting cable (18) between the two clamping parts (36, 38), wherein the first clamping part (36) is secured to the first housing part (12) in such a way that the first clamping part (36) is fixed to the first housing part (12) both axially and rotationally, wherein the first housing part (12) is designed to provide a positively locked connection for a cable gland (16) is trained,in which a locking device (30) is provided on the first clamping part (36) for locking the first clamping part (36) to the first housing part (12).

Description

The invention relates to a power tool having a cable strain relief, having a first clamping part and a second clamping part interacting therewith for clampingly fixing a connecting cable between the two clamping parts, wherein the first clamping part has means for fixing in a first housing part of the power tool and the second clamping part can be connected to the first clamping part or the first housing part in order to fix the connecting cable between the two clamping parts.In the case of electric tools, there are safety regulations according to which a connecting cable for an electric tool must be reinforced with a cable bushing at the location of the housing passage in order to prevent damage to the electrical insulation due to buckling. In addition, the electrical connection cable must be secured against being pulled out ("cable strain relief") in the housing of the electric tool. The fixing unit required for this purpose must in turn have a connection to the housing of the electric tool, which connection can be released only with the aid of a tool.In the prior art, dome-like clamping structures are usually used for this purpose, which are firmly connected to the housing of the electric tool and do not have undercuts, which can be used directly as installation space by other components, such as electronic components or mechanical components.Furthermore, the integration of the clamping structures directly into the housing of the electric tool results in the entire housing having to be replaced in the event of damage to the clamping structure, which represents a great expenditure of time or cost. Furthermore, there is the disadvantage that in the event of a change of the connecting cable, the clamping structures provided on the housing must be adapted accordingly. This means that the expensive casting molds for the injection molding production of the housing shells may have to be changed or newly produced.DE 34 33 234 A1 discloses a cable strain relief device which consists of two elements which can be locked to one another for receiving a cable and which can be fixed to a housing of an electric tool. Further prior art is known from DE 94 12 042 U1.DE 10 2008 002 616 A1 further discloses a power tool having a cable bushing for receiving a connecting cable, which can be fixed to a housing part of the power tool by means of radial sealing means.DE 34 33 234 A1 relates to a cable feedthrough which can be held on a fixed part such as a plate, switch panel, a device housing wall or a chassis and holds a cable inserted into it. In the grommet, a member for holding the cable inserted into the grommet is provided separately from a holding part with which the grommet is held to the fixed part.DE 10 2008 002 616 A1 relates to a cable bushing for guiding a cable in its inlet and outlet region of a hand-held power tool housing, which cable bushing is connected, in particular in a positively locking manner, to the housing by its end on the housing side.DE 20 2008 004 614 U1 relates to a device for securely holding at least one wire, having two housing parts which can be joined together and which hold the at least one wire in a clamping manner in the joined state, wherein one of the two housing parts has a central wall which has a contact surface for the at least one wire, and wherein the other housing part has two mutually opposite walls which, in the joined state of the housing parts, run parallel to the central wall, in such a way that a loop-shaped or wave-shaped guide for the at least one wire is formed.DE 29 719 337 U1 relates to a house connection box with a tension-proof cable arrangement and a tension relief device, in particular for house connection boxes in which there is a greater distance from the meter.DE 295 17 229 U1 relates to a cable arresting device in a housing in electrical connection technology. In the feed technology for distribution cabinets or meter cabinets, the electrical cables which are fed and introduced into the corresponding housings are fixed in position on the housing.DE 38 20 741 A1 relates to an electrically operated hand tool, in particular a drilling device, with a housing, a power cable opening into the housing and the power cable in the region of the opening into the cable bushing surrounding the housing.Against this background, the object of the invention is to provide a power tool with a cable strain relief which allows greater flexibility with regard to changes to the housing of the power tool or to the connection cable of the power tool and nevertheless ensures a defined position of the connection cable on the housing of the power tool. Furthermore, the overall size of the cable strain relief should preferably be as compact as possible in order to enable the best possible use of space when used on an electric tool.This object is achieved by a power tool according to claim 1.The object of the invention is achieved in this way.According to the invention, the cable strain relief consists of two mutually cooperating clamping parts which can be secured to the first housing part of the electric tool in a predetermined position both in the axial direction and in the rotational direction. If the cable strain relief becomes unusable during operation of the electric tool, a new cable strain relief comprising the two mutually cooperating clamping parts can be fastened to the housing in this case in a simple manner.If, on the other hand, the requirements for the connecting cable in the case of an electric tool change over time, a correspondingly changed cable strain relief can easily be installed on the housing without the housing itself having to be changed for this purpose.Since the two clamping parts can be configured compactly and can be fixed in a simple manner to the first housing part, overall, an improved utilization of space in the housing of the electric tool can also be achieved.In an advantageous development of the invention, a latching means for latching the first clamping part to the housing part is provided on the first clamping part.This results in a simple and secure fixing of the first clamping part to the first housing part. In addition, a particularly simple attachment of a connecting cable results.In an additional development of the invention, the latching means on the first clamping part is designed in such a way that a latching connection to the first housing part can be released only by means of a tool.This ensures increased security against incorrect assembly or against unauthorized interventions by a user.In an additional development of the invention, the latching means is designed as a snap hook which is designed for latching on an associated latching receptacle on the first housing part.This results in a particularly simple and reliable configuration of the latching connection.According to a further embodiment of the invention, the latching means is designed for the positive fixing of the first clamping part to the first housing part in a predetermined position.In this way, the fixing of the first clamping part in the predetermined position can also be achieved simultaneously with the latching.According to a further embodiment of the invention, the second clamping part can be detachably connected, in particular screwed, to the first clamping part or the first housing part.Furthermore, at least one of the two clamping parts is preferably convexly curved when viewed from the respective other clamping part. These features provide a simple and secure possibility for secure fastening of the connecting cable in order to bring about secure strain relief.According to a further embodiment of the invention, the two clamping parts are designed to receive connecting cables with different cable cross sections or different cable sheathings.To a certain extent, this can be ensured by the above-described embodiment with the convex curvature of at least one of the clamping parts.The object of the invention is furthermore achieved by a power tool having at least two housing parts, with a cable strain relief according to the type described above.In this case, a latching receptacle is preferably provided on a housing part, which receptacle interacts with the latching means of the first clamping part for fixing it in a latching position.In this way, a simple and reliable fixing of the first clamping part to the first housing part is made possible.According to a further development of this embodiment, at least one form-fitting element is provided on the first housing part, which interacts with the first clamping part for its form-fitting fixing in the latching position in a predefined position on the first housing part.This measure makes it possible to ensure in a particularly simple manner that the first clamping part is fastened in the desired position on the first housing part when the latching connection is produced.According to a further feature of the invention, at least the latching receptacle on the first housing part is designed to receive different first clamping parts for different connecting cables.In this way, with more widely varying connecting cables, it is possible to ensure that the cable strain relief on the housing is accommodated without the housing itself having to be changed. For this purpose, only the first clamping part and, if appropriate, the associated second clamping part must be adapted accordingly. The latching connection and the form-fitting fixing on the first housing part are maintained unchanged here.According to a further feature of the invention, the at least one form-fitting element interacts with the first clamping part in such a way that an exchange-proof fastening of the first clamping part to the housing part is ensured.In this way, assembly errors during the assembly of the cable strain relief on the housing are avoided.According to a further feature of the invention, the first housing part is designed for positively secured reception of a cable grommet.For this purpose, an annular recess for receiving one end of a cable grommet can be provided, for example on the first and second housing part adjacent to the first and second clamping parts.In this way, a secure fixing of the cable bushing to the housing is ensured.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the invention.Further features and advantages of the invention will become apparent from the following description of a preferred exemplary embodiment with reference to the drawing. The following are shown: FIG. 1 is a perspective partial view of an electric tool according to the invention, in which a cable strain relief according to the invention is accommodated in the rear end of a housing; FIG. 2 shows a first perspective view of the housing according to FIG. 1, in which the associated second housing part is removed, with the cable strain relief device fully mounted; FIG. 3 shows a second perspective view of the housing according to FIG. 2 ; FIG. 4 is a side view of the representation according to FIG. 2 ; FIG. 5 is a top view of the upper housing shell with the cable strain relief device fully mounted; FIG. 6 is a top view according to FIG. 5, but after disassembly of the second, upper clamping part and the connecting cable, and FIG. 7 is a top view according to FIG. 6, but after the lower clamping part has been removed.In FIG. 1, a power tool according to the invention is partially illustrated and denoted overall by the numeral 10.This can be any desired electric tool, for example a drilling machine, a screwdriver, a grinding machine or the like.In any case, the electric tool 10 has at least two housing parts 12, 14 which can be detachably connected to one another. The two housing parts 12, 14 together form in the region shown a closed housing, from the rear end of which a connecting cable 18 projects, which is surrounded by a cable grommet 16. This connecting cable 18 is fastened with a cable strain relief device according to the invention, as is explained in more detail below with reference to FIGS. 2, 3, 4, 5, 6 to 7.FIG. 2 shows a perspective illustration of the electric tool according to FIG. 1 after removal of the lower, second housing part 14, together with the connection cable 18 and with a fully assembled cable strain relief 20, The first housing part 12 here comprises only the rear end of the housing, in the region of which the connection cable 18 is assembled together with the cable strain relief 20. It is understood that the first and second housing parts are generally adjoined by further housing parts, in which the remaining parts of the electric tool are accommodated, or that the housing parts 12, 14 are only parts of a larger housing.The housing parts 12, 14 are usually made of a shock-resistant plastic and are usually produced by injection molding. In this case, the webs, recesses, mounting points, screw receptacles and the like required for the later mounting are already introduced together during injection molding.In the embodiment according to the invention, the cable strain relief 20 is now not formed directly onto the housing parts, but rather is fastened to the first housing part 12 using two clamping parts, namely a first, lower clamping part 36 and a second, upper clamping part 38 interacting therewith.The connecting cable 18 is surrounded by a cable grommet 16 which is closed at its end on the appliance side by an annular web 44, with which a form-fit reception of the cable grommet 16 is ensured both in the first housing part 12 and in the second housing part 14.The two clamping parts 36, 38, which together serve for clamping fixation of the connecting cable 18 running through the cable bushing 16 and through the cable strain relief 20, have outwardly conically curved clamping surfaces, between which the connecting cable 18 is clamped when the second clamping part 38 is screwed on. The screws used for this purpose can be seen in FIG. 2 at 40 and 42. When the second clamping part 38 is screwed on above the connecting cable 18 into the first clamping part 36, the relevant screws 40, 42 additionally engage into the first housing part 12, so that the connecting cable 18 is securely fixed and relieved of tension between the two clamping parts 36, 38 on the first housing part 12.The first clamping part 36 is fastened to the first housing part 12 in a predetermined position by a snap-in connection. For this purpose, FIG. 2 shows a latching hook 30 on the first clamping part 36, which is latched to a latching receptacle 32 on the first housing part 12. It can be seen in FIG. 2 that for this purpose a latching nose at the lower end of the latching hook 30 is latched behind an associated projection of the latching receptacle 32.

[0048] The latching connection thus formed between the first clamping part 36 and the first housing part 12 is configured in such a way that the latching connection can be released again only with the aid of a tool, for example a screwdriver.Directly adjacent to the cable strain relief 20, a switch 22 is mounted on the first housing part 12 and is connected on the machine side via a connecting line 28. The ends (not shown) of the connecting cable 18 protruding from the cable strain relief 20 on the machine side can be directly connected to the switch 22.The special configuration of the cable strain relief 20 results in a particularly compact construction which makes it possible to arrange further components even below the cable strain relief 20, for example a switching pin 24 projecting from the switch 20 and an associated switching rod 26 for actuating the switch 20.In FIG. 5, the cable bushing 16 and the cable strain relief can be completely seen in a plan view, wherein, however, the illustration of the associated connecting cable 18 has been omitted. As can be seen from FIG. 5, the switching pin 24 of the switch 22 is located under the cable strain relief 20, and the two clamping parts 36, 38 of the cable strain relief 20 together form an approximately L-shaped bridge-like structure which is fixed to the first housing part 12.In the top view according to FIG. 5, the screw 40 can be seen, by means of which the second clamping part 38 is screwed to the associated screw receptacle 48 on the first housing part 12 above the connection cable 18 (not shown), in order to ensure the clamping fixation of the connection cable 18 held underneath.FIG. 6 shows the arrangement according to FIG. 5 from above, after removal of the second clamping part 38 and after removal of the connecting cable 18 with cable sleeve 16.At the cable-side end of the first housing part 12 there is a semi-cylindrical depression with two sections 52, 54, which is adapted to the shape of the cable grommet 16 in such a way that the cable grommet 16 bears in the first section 52 and can be held in a form-fitting manner in the associated second section 54, which has a correspondingly enlarged diameter, by means of the end-side annular web 44 protruding outwards from the cable grommet 16.It is understood that a corresponding recess is formed in the associated second housing part 14, which recess corresponds to the first section 52 and the second section 54 of the first housing part 12.The first clamping part 36, which is fixed by the latching connection on the first housing part 12, has a cable receptacle curved convexly outwards for clampingly fastening the connecting cable 18.FIG. 7 shows the arrangement according to FIG. 6 from above, but after removal of the first clamping part 36.FIGS. 6 and 7 show a screw receptacle 48 formed integrally on the first housing part 12, on which the second clamping part 38 is fastened by the associated screw 40 in order to clamp the connecting cable 18 between the two clamping parts 36, 38 and thus to realize strain relief. The screw receptacle 46, which is also visible in FIGS. 6 and 7, serves only for screwing the two housing parts 12, 14.In FIG. 7, positive locking elements indicated at 56 and 58 can also be seen, which cooperate with associated elements on the first clamping part 36 in order to ensure a replacement-proof receptacle and at the same time a positionally correct positioning on the first housing part 12 during the snap-fitting of the first clamping part 36 on the first housing part 12.The mutually cooperating clamping surfaces on the first housing part 36 and on the second housing part 38, which are both convexly curved outwards, allow cable diameters to be accommodated which differ from one another in terms of size by a certain amount.However, if connecting cables 18 with a significantly larger or smaller connecting cable diameter are to be mounted on the electric tool 10, this can no longer be realized with the same clamping parts 36, 38. For this purpose, however, correspondingly adapted clamping parts can be used, which are adapted to the changed cable diameter and which can otherwise be fastened to the latching receptacle 32 by latching, taking into account the associated positive locking elements 56, 58 on the first housing part 12.Conversely, if the cable strain relief 20 should be damaged, the entire cable strain relief 20 can be easily replaced with the aid of a tool such as a screwdriver.

Claims

Power tool (10) having at least two housing parts (12, 14), having a cable strain relief with a first clamping part (36) and a second clamping part (38) interacting therewith for clamping fixing a connection cable (18) between the two clamping parts (36, 38), wherein the first clamping part (36) has means (30) for fixing in a first housing part (12) of the power tool (10) and the second clamping part (38) can be connected to the first clamping part (36) or the first housing part (12) in order to fix the connection cable (18) between the two clamping parts (36, 38), wherein the first clamping part (36) is fixed to the first housing part (12) in a positionally secured manner such that the first clamping part (36) is fixed to the first housing part (12) both in the axial direction and in the rotational direction, in which the first housing part (12) is designed for receiving a cable sleeve (16) in a positively secured manner, wherein a latching means (30) is provided on the first clamping part (36) for latching the first clamping part (36) to the first housing part (12).Electric tool according to claim 1, in which the latching means (30) on the first clamping part (36) is designed in such a way that a latching connection to the first housing part (12) can be released only by means of a tool.Electric tool according to one of the preceding claims, in which the latching means (30) is designed as a snap hook which is designed for latching on an associated latching receptacle (32) on the first housing part (12).Electric tool according to one of the preceding claims, in which the latching means (30) is designed for the positive fixing of the first clamping part (36) on the first housing part (12) in a predetermined position.Electric tool according to one of the preceding claims, in which the second clamping part (38) can be detachably connected, in particular screwed, to the first clamping part (36) and / or the first housing part (12).Electric tool according to one of the preceding claims, in which at least one of the two clamping parts (36, 38) is convexly curved as seen from the respective other clamping part.Electric tool according to one of the preceding claims, in which the two clamping parts (36, 38) are designed to accommodate connecting cables (18) having different cable cross sections or different cable sheathings.Electric tool according to one of the preceding claims, in which a latching receptacle (32) is provided on the first housing part (12), which receptacle interacts with the latching means (30) of the first clamping part (36) for fixing it in a latching position.Electric tool according to claim 8, in which at least one form-fitting element (56, 58) is provided on the first housing part (12), which element interacts with the first clamping part (36) for its form-fitting fixing in the latching position in a predetermined position on the first housing part (12).The electric tool according to claim 8 or 9, wherein at least the latching receptacle (32) on the first housing part (12) is configured to receive different first clamping parts (36) for different connecting cables (18).Electric tool according to Claim 9 or 10, in which the at least one form-fitting element (56, 58) interacts with the first clamping part (36) in such a way that an exchange-proof fastening of the first clamping part (36) to the first housing part (12) is ensured.The power tool of any preceding claim, wherein the first (12) and second (14) housing portions adjacent the first (36) and second (38) clamping portions are provided with an annular recess (52, 54) for receiving an end of a grommet (16).

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