Auxiliary handle with eccentric clamping lever for a hand-held power tool

The invention relates to an additional hand grip (2) for a hand machine tool, comprising a clamp (4) for clamping the additional hand grip (2) to a part of the hand machine tool, a handlebar (6) for gripping and holding of the additional hand grip (2), and a pivot joint (8) that can be blocked, arranged between the clamp (4) and the handlebar (6). The pivot joint (8) can be blocked with an eccentric tension lever (10), which is formed by a pivotable part (24) of the handlebar (6).

The present invention relates to an auxiliary handle for a hand-held power tool, according to the preamble of Claim1.

RELATED ART

An auxiliary handle for a hand-held power tool is made known in FIGS. 4 and 5 of DE 101 30 548 A1 which belongs to the applicant, that is fixedly clamped to a part of a rotary hammer using a clamp, includes a handlebar for gripping and holding the auxiliary handle, and that includes a pivot joint located between the clamp and the handlebar.

In addition, the applicant already offers and sells auxiliary handles of the type described initially, with which the pivot joint may be blocked by using the fixing T-handle and a clamping screw, to fix the handle relative to the clamp in a desired pivot position around the pivot axis of the pivot joint, and to fix the clamp relative to the machine tool in a desired rotational position around the center of a circle formed by the clamp. The fixing T-handle includes an internally threaded bore, in which an end—which includes an external thread—of the clamping screw engages, the clamping screw extending along the pivot axis of the pivot joint through flush openings in three joint sleeves of the auxiliary handle that enclose the pivot axis. The two outer joint sleeves are non-rotatably connected with the handle, while the inner joint sleeve—which is divided into two in the axial direction via a slotted opening in the clamp—is non-rotatably connected with the clamp.

By tightening the fixing T-handle, the two outer joint sleeves may be pressed via their inwardly facing, toothed ends against the adjacent end of the inner joint sleeve, which has complementary toothing. When the pivot joint is blocked, the opposing teeth engage in a form-fit manner and prevent the handle from swiveling relative to the clamp when a large pressing force is applied to the handlebar, e.g., when an operator is working with the hand-held power tool. Since the teeth are designed to be extremely rough, i.e., with a tooth height of approximately 2.5 mm, adjacent joint sleeves must be moved apart by at least this amount before the handlebar may be displaced, to prevent the handle from accidentally becoming displaced when the pivot joint is blocked, and to prevent the wear that would result on the teeth that are pressed together. To this end, the fixing T-handle must cover a displacement path of more than 5 mm, which corresponds to several rotations of the fixing T-handle, which many craftsmen consider to be too tedious. Further perceived disadvantages are that the operator is unable to use the fixing T-handle—which extends beyond an end of the pivot joint—during operation of the hand-held power tool, that the fixing T-handle is not particularly aesthetically pleasing, and that it may even hinder handling of the hand-held power tool in tight conditions.

The object of the present invention, therefore, is to improve an auxiliary handle of the type described initially such that it does not include projecting parts that interfere with work and detract from the appearance, and that a component of the auxiliary handle that is already present and also performs another function may be used to displace the handlebar with a minimum of effort.

DISCLOSURE OF THE INVENTION

This object is attained according to the present invention in that the pivot joint is blockable using an eccentric clamping lever that is designed as a swivelable part of the handlebar.

Similar to the fixing T-handle of the known auxiliary handle, the eccentric clamping lever serves to block the pivot joint and, simultaneously, to tighten the clamp, and, by swiveling it in the opposite direction, to release the pivot joint and loosen or release the clamp before the handlebar is displaced relative to the clamp and/or before adjusting the clamp and, therefore, the entire auxiliary handle, relative to the hand-held power tool.

According to a preferred embodiment of the present invention, the pivot joint includes at least one articulated part that is non-rotatably connected with the clamp, and at least one articulated part that is non-rotatably connected with the handlebar, the two articulated parts being rotatable relative to each other around a pivot axis of the pivot joint in order to displace the handlebar, and which may be pressed against each other to block the pivot joint by swiveling the eccentric clamping lever in the axial direction of the pivot axis.

Advantageously, the handlebar and the handlebar of the known auxiliary handle include a yoke part that is located opposite to the pivot joint and is parallel to the pivot axis, and two leg parts that connect the yoke part with the pivot joint. In contrast to the known auxiliary handle, one of the two leg parts is swivelable and serves as the eccentric clamping lever.

According to a further preferred embodiment of the present invention, the eccentric clamping lever is brought into form-fit engagement with the yoke part and is optionally snapped in place with the yoke part when it is swiveled into a position that is parallel with the other leg part in order to block the pivot joint. In this position, the free end of the eccentric clamping lever engages seamlessly in the yoke part of the handlebar, so that it encloses a grip opening on all sides and serves as a stable unit during operation of the hand-held power tool.

The eccentric clamping lever is preferably hingedly connected to a clamping bolt that extends in the axial direction of the pivot axis of the pivot joint through openings in the articulated parts and pulls them together when the eccentric clamping lever is swiveled. As a result, at least two diametrically opposed sets of teeth on adjacent contact surfaces of two articulated parts of the pivot joint that are non-rotatably connected with the clamp and/or the handlebar are brought into a form-fit, toothed engagement, thereby blocking the articulated parts relative to each other. When the eccentric clamping lever is swiveled in the opposite direction in order to displace the handlebar or rotate the clamp to release the blocked pivot joint or expand the clamp, the articulated parts may be moved so far apart from each other in the axial direction of the pivot axis that the diametrically opposed teeth may slide past each other. A total of only pair of diametrically opposed teeth is preferably provided, to avoid having to move the articulated parts apart from each other to a considerable extent before the articulated parts of the handlebar and the articulated parts of the clamp may be rotated relative to each other.

Advantageously, the eccentric clamping lever is hingedly connected to the clamping bolt as an extension of the pivot axis of the pivot joint, and it is provided with a pressing surface that is eccentric to its rotational axis, and that moves along an opposite pressing surface of an adjacent articulated part when the eccentric clamping lever is swiveled around the rotational axis, thereby ensuring that the articulated part moves in the axial direction of the pivot axis of the articulated joint.

To ensure that the free end of the eccentric clamping lever may always be engaged seamlessly with the yoke part of the handlebar, regardless of the pivot position of the handlebar that is selected relative to the clamp, the clamping bolt is non-rotatably connected with the handlebar, thereby enabling the eccentric clamping lever—which is hingedly connected to the clamping bolt—to be displaced along with the handlebar when it is displaced.

EMBODIMENTS OF THE INVENTION

Auxiliary handle2—shown in the drawing—for use with hand-held power tools, such as drills, rotary hammers, or the like, includes a clamp4, with which auxiliary handle2may be fixedly clamped to a cylindrical part (not shown) of the housing of the machine tools, e.g., a cylindrical shank part behind a tool fitting on drills or rotary hammers, a handlebar6, at which auxiliary handle2may be gripped by an operator, a blockable pivot joint8located between clamp4and handlebar6, with which the operator may select a desired pivot setting of handlebar6relative to clamp4and/or a desired rotational position of clamp4and, therefore, of entire auxiliary handle2relative to the cylindrical part of the machine tool equipped with auxiliary handle2. Auxiliary handle2also includes an eccentric clamping lever10, with which pivot joint8may be blocked and clamp4may be tightened, in order to lock handlebar6in a previously selected pivot position around a pivot axis12of pivot joint8relative to clamp4, and to lock clamp4in a previously selected rotational position around its central axis14relative to the machine tool.

As best shown inFIG. 5, clamp4is composed of a shaped plastic part16that is manufactured as a single piece via injection molding and is designed as a ring that is open on one side, which is provided with a slotted opening18that points toward handlebar6. The width of slotted opening18may be changed by actuating eccentric clamping lever10, in order to tighten clamp4by reducing its diameter, for fixation on the machine tool, and to remove or loosen the tightened, tensioned clamp4by increasing its diameter.

Handlebar6is composed essentially of a yoke part, which is used for gripping and is essentially parallel to pivot axis12of pivot joint8, and two leg parts22and24, one (22) of which is rigidly connected with yoke part20, while the other (24) serves as swivelable eccentric clamping lever10that is used to block pivot joint8. When pivot joint8is blocked, the two leg parts22and24are oriented essentially parallel to each other and enclose—along with yoke part20and pivot joint8—a grip opening26for the hand of the operator that has been placed around yoke part20.

Pivot joint8is composed essentially of a cylindrical clamping bolt28with an expanded, hexagonal head part30(FIG. 5), a cylindrical shank part32, and a transverse bore34in the end—that is diametrically opposed to head part30—of shank part32, and of three plastic joint sleeves36,38,40, which enclose clamping bolt28. Two outer joint sleeves36,40are located on diametrically opposed sides of pivot joint8and are non-rotatably connected with handlebar6, while an inner joint sleeve38—which is divided in two by slotted opening18—is designed as a single piece with plastic part16of clamp4and extends on both sides of slotted opening18to adjacent outer joint sleeve36or40.

When pivot joint8is blocked, to prevent handlebar6from accidentally swiveling relative to clamp4due to a pressing force applied to handlebar6, it is provided with the exemplary embodiment shown inFIGS. 1 through 5to provide the outwardly facing ends of inner joint sleeve38and the adjacent, inwardly facing ends of the two outer joint sleeves36and40with complementary tooth systems42. Tooth systems42are composed of a plurality of radial teeth that extend from a cylindrical opening for clamping bolt28to a cylindrical outer circumferential surface of joint sleeve36,38,40, extend axially beyond their ends, and are separated by complementary tooth gaps.

Tooth systems42may therefore engage essentially without play when—in a plurality of discrete setting positions of handlebar6relative to clamp4—the teeth come to bear against the ends of outer joint sleeves36,40via the tooth gaps of the adjacent ends of inner joint sleeve38, and vice versa.

Expanded head part30of clamping bolt28is accommodated in a complementary blind hole44in joint sleeve36that serves as an anti-rotation lock when clamping bolt28is slid through joint sleeves36,38,40in the direction of arrow A inFIG. 5when the auxiliary handle is installed via its shank part32, until the end provided with transverse bore34extends outwardly beyond joint sleeve40on the opposite side of pivot joint8. As an alternative, clamping bolt28could also be embedded via its head part30in joint sleeve36and thereby be non-rotatably connected with joint sleeve36when it is manufactured out of plastic as a single piece with yoke part20and leg part22via injection molding during manufacture of handlebar6.

Transverse bore34serves to accommodate a pivot pin46, which may be inserted—when eccentric clamping lever10is installed on clamping bolt28—in flush bores in legs48(FIG. 4) of a fork-shaped end of eccentric clamping lever10, and through transverse bore34, and may be subsequently staked in order to fix it in position in fork legs48. The outer diameter of pivot pin46is adapted to the inner diameter of transverse bore34such that eccentric clamping lever10—after it has been installed on clamping bolt28—is rotatable around a rotational axis formed by central axis of transverse bore34.

The two fork legs48of eccentric clamping lever10are bounded at their free ends by convex pressing surfaces50with cross sections shaped as circular arcs. Pressing surfaces50are eccentric to the rotational axis of eccentric clamping lever10and each bear against an opposite concave pressing surface52on the outside of outer joint sleeve40. Pressing surfaces50of eccentric clamping lever10and pressing surfaces52of joint sleeve40are adapted to each other such that the two outer joint sleeves36,40are pressed together in the axial direction of pivot axis12when eccentric clamping lever10is swiveled out of the pivot position shown inFIG. 3and into the pivot position shown inFIG. 1in order to block pivot joint8and fixedly clamp clamp4on the hand-held power tool. The two outer joint sleeves36,40are moved apart from each other in the axial direction of pivot axis12due to the tension created when clamp4is tightened when eccentric clamping lever10is moved out of the pivot position shown inFIG. 1and into the pivot position shown inFIG. 3in order to displace handlebar6relative to clamp4and/or to rotate clamp4on the hand-held power tool. In the pivot position shown inFIG. 3, tooth systems42—which are located opposite to each other in pairs—on the ends of joint sleeves36,38,40may be rotated relative to each other.

To ensure that eccentric clamping lever10—when in the pivot position shown in FIG.1—is a stable, closed unit with the rest of handlebar6that encloses grip opening26on all sides, eccentric clamping lever10includes—on its free end—a projection54that projects on one side and engages in a complementary recess56in the opposite end of yoke part20and may snap in place in the recess in order to provide a “seamless” transition between the free end of eccentric clamping lever10and yoke part20.

In contrast to the exemplary embodiment described above, with the exemplary embodiment described with reference toFIG. 6, only one tooth system42is located between adjacent joint sleeves38and40, while the opposite ends of joint sleeves36and38are not provided with toothing. The amount of axial travel that joint sleeve40must cover on clamping bolt28until joint sleeves36and40may be rotated relative to joint sleeve38may therefore be reduced by half.

To compensate for production tolerances of the clamping diameter of the cylindrical part of the hand-held power tool on which clamp4is detachably attached via fixed clamping, the effective length of clamping bolt28may be changed, as shown inFIGS. 7 and 8.

With auxiliary handles2with clamping bolts28that are manufactured separately from joint sleeve36and are slid through all joint sleeves36,38,40when auxiliary handles2are assembled, one or more spacers58is/are inserted—as needed and for this purpose—between head part30of clamping bolt28and the base of blind hole44in joint sleeve36, as shown inFIG. 7.

With clamping bolts28whose expanded head30is embedded in the plastic material of joint sleeve36during the injection molding of yoke part20, leg part22, and joint sleeve36, the end of clamping bolt28that is opposite to head part30may be provided not with transverse bore34but with a slot60that passes through clamping bolt28, and with an external thread62over at least a portion of slot60. An adjusting nut64is screwed onto external thread62, with which the position of pivot pin46of eccentric clamping lever10along slot60may be adjusted and, therefore, so may the effective length of clamping bolt28, as shown inFIG. 8.