Patent Description:
The present invention relates to a percussion tool according to the preamble of claim <NUM> as well as to a percussion tool according to the preamble of claim <NUM>. Such a percussion tool is known from <CIT>.

Percussion tools can use tool holders to hold a chisel. A percussion mechanism of the percussion tool can include a striker to impart repeated axial impacts to the chisel, which in turn repeatedly impacts a workpiece or surface. The chisel can be inserted into the tool holder so as to abut the striker in order to receive the repeated axial impacts.

According to the present invention there is provided a percussion tool for performing a chiseling operation on a workpiece with a chisel comprising the features of claim <NUM>. The percussion tool comprises a housing, an electric motor positioned within the housing, and a percussion mechanism driven by the motor and including a striker supported for reciprocation relative to the housing along a longitudinal axis. The percussion tool further comprises a tool holder coupled to the housing and including a rotatable handle having a rod that rotates with the handle within the tool holder. The chisel is securable in and removable from the tool holder. The chisel has a longitudinal groove that is substantially parallel with the longitudinal axis. When the chisel is secured in the tool holder, the chisel is permitted to axially reciprocate within the tool holder in response to receiving repeated axial impacts from the striker. The handle is moveable between a first position, in which the rod is received in the groove and the chisel is secured in the tool holder, and a second position, in which the rod is removed from the groove and the chisel is removable from the tool holder. When the handle is in the second position, an acute angle is defined between a first reference plane defined by the handle and a second reference plane that is perpendicular to the longitudinal axis. The acute angle is <NUM> degrees or less.

Also according to the present invention there is provided a percussion tool for performing a chiseling operation on a workpiece with a chisel comprising the features of claim <NUM>. The percussion tool comprises a housing, an electric motor positioned within the housing, and a percussion mechanism driven by the motor and including a striker supported for reciprocation relative to the housing along a longitudinal axis. The percussion tool further comprises a tool holder coupled to the housing and including a rotatable handle having a cylindrical rod defining an axis of rotation of the handle. The rod has a recessed portion and an opposite arcuate portion defined by a circumference of the rod. The chisel is securable in and removable from the tool holder. The chisel has a longitudinal groove that is substantially parallel with the longitudinal axis. When the chisel is secured in the tool holder, the chisel is permitted to axially reciprocate within the tool holder in response to receiving repeated axial impacts from the striker. The handle is moveable between a first position, in which the arcuate portion is received in the groove and the chisel is secured in the tool holder, and a second position, in which the arcuate portion is removed from the groove, the recessed portion is in facing relationship with the groove, and the chisel is removable from the tool holder. The arcuate portion defines an angle of <NUM> degrees or less along the circumference of the rod with respect to the axis of rotation of the handle.

By way of example, described herein is a percussion tool for use with a chisel. The percussion tool comprises a housing including a cylinder portion and a tool holder coupled to the cylinder portion for holding the chisel. The percussion tool further comprises a percussion mechanism including a striker supported for reciprocation in the cylinder portion, the percussion mechanism configured to impart repeated axial impacts to the chisel via the striker. The percussion tool also comprises a flange between the cylinder portion and the tool holder, wherein movement of the chisel within the tool holder toward the percussion mechanism is stopped by the flange.

With reference to <FIG> and <FIG>, a percussion tool <NUM>, such as a breaker, includes a housing <NUM> having a cylinder portion <NUM>. A percussion mechanism <NUM> is disposed in the housing <NUM> and can be any suitable percussion mechanism, including but not limited to pneumatic, hydraulic, motor-driven, or electromagnetic. The percussion mechanism <NUM> includes a striker <NUM> supported for reciprocation along a longitudinal axis <NUM> in the cylinder portion <NUM>.

A tool holder <NUM> for holding a chisel 34a, 34b is coupled to the cylinder portion <NUM>. As will be explained in further detail below, the tool holder <NUM> is adapted to hold a variety of chisels. For example, the tool holder <NUM> is adapted to hold a chisel 34a with a radially inward-extending longitudinal groove <NUM> as shown in <FIG>. The groove <NUM> is parallel with the longitudinal axis <NUM> when the chisel 34a is received in the tool holder <NUM>. The tool holder <NUM> is also adapted to hold a chisel 34b that has a radially outward-extending flange <NUM> instead of a longitudinal groove, as shown in <FIG>. The percussion mechanism <NUM> is configured to impart repeated axial impacts to the chisel 34a, 34b via the striker <NUM>, so that a breaking operation or chiseling operation may be performed on a workpiece or surface.

The tool holder <NUM> includes a rotatable handle <NUM> that can rotate between a first position shown in <FIG>, <FIG>, <FIG> and <FIG>, and a second position shown in <FIG> and <FIG>. The handle <NUM> includes an eccentric pin <NUM> rotatable therewith within a lateral recess <NUM> of the tool holder <NUM>. If an operator elects to use chisel 34a with the percussion tool <NUM>, rotation of the handle <NUM> to the first position causes the eccentric pin <NUM> to move radially inward within the recess <NUM>, thereby engaging the longitudinal groove <NUM>. Thus, if the operator tips the percussion tool <NUM> in such a manner that the chisel 34a might be caused to fall out of the tool holder <NUM>, the eccentric pin <NUM> will contact a rear end <NUM> of the longitudinal groove <NUM> to prevent the chisel 34a from falling out. During operation of the percussion tool <NUM>, as the striker <NUM> imparts axial blows to the chisel 34a along the longitudinal axis <NUM>, the chisel 34a reciprocates within the tool holder <NUM> between forward and rearward positions where the eccentric pin <NUM> is maintained between the rear end <NUM> of the longitudinal groove and an opposite front end <NUM> of the longitudinal groove <NUM>.

The handle <NUM> also includes a finger <NUM>. If an operator elects to use chisel 34b with the percussion tool <NUM>, the handle <NUM> is rotated to the second positon in which the finger <NUM> abuts the chisel 34b. As shown in <FIG> and <FIG>, rotation of the handle <NUM> to the second position also causes the eccentric pin <NUM> to move radially outward in the recess <NUM>, so as to avoid interfering with chisel 34b within the tool holder <NUM>, because chisel 34b does not have a longitudinal groove. Thus, if the operator tips the percussion tool <NUM> in such a manner that the chisel 34b might be caused to fall out of the tool holder <NUM>, the finger <NUM> will contact the radially outward-extending flange <NUM> and prevent the chisel 34b from falling out.

A radially inward-extending flange <NUM> with an inner diameter <NUM> is located between the cylinder portion <NUM> and the tool holder <NUM>. In a first embodiment of the invention shown in <FIG>, the inner diameter <NUM> of the flange <NUM> is less than an outer diameter <NUM> of either of the chisels 34a, 34b, and greater than an outer diameter <NUM> of the striker <NUM>. Thus, when an operator inserts either of the chisels 34a, 34b into the tool holder <NUM>, movement of the chisels 34a, 34b within the tool holder <NUM> toward the percussion mechanism <NUM> is stopped in response to the chisels 34a, 34b abutting the flange <NUM> (as shown in each of <FIG>).

In another embodiment of a percussion tool shown in <FIG> and <FIG>, with like features being identified with like reference numerals, the tool holder <NUM> includes a recess <NUM> to accommodate an axially moveable sleeve <NUM>. The sleeve <NUM> has a first end <NUM> with a first end outer diameter <NUM> that is greater than the inner diameter <NUM> of the flange <NUM>. The sleeve <NUM> has an opposite second end <NUM> with a second end inner diameter <NUM> that is less than the outer diameter <NUM> of each of the chisels 34a, 34b. A striking end <NUM> of the striker <NUM> has an outer diameter <NUM> that is nominally less than the inner diameter <NUM> of the second end <NUM> of the sleeve <NUM>, so that the striking end <NUM> may pass through the sleeve <NUM> and strike the chisels 34a, 34b. The chisels 34a, 34b axially move within a hollow portion <NUM> of the sleeve <NUM>. Thus, when an operator inserts either of the chisels 34a, 34b into the tool holder <NUM>, movement of the chisels 34a, 34b within the tool holder <NUM> toward the percussion mechanism <NUM> is stopped in response to the chisels 34a, 34b abutting the second end <NUM> of the sleeve <NUM>, and the first end <NUM> of the sleeve <NUM> abutting the flange <NUM> (as shown in <FIG>).

The flange <NUM> limits the distance the chisels 34a, 34b can be inserted into the tool holder <NUM>, thereby preventing damage to the percussion mechanism <NUM> and allowing the point of impact between the striker <NUM> and the chisels 34a, 34b to remain consistent. Also, regardless of which of the chisels 34a, 34b an operator selects, the same percussion tool <NUM> may be used because the tool holder <NUM> is adapted to hold a variety of chisels.

<FIG> illustrates another embodiment of a tool holder 30a for use with the breaker <NUM> of <FIG>, with like components shown with like reference numerals. The tool holder 30a includes a handle 46a having a rod <NUM> extending between opposite ends <NUM>, <NUM> of the handle 46a (see also <FIG>), two legs <NUM> respectively extending from the opposite ends <NUM>, <NUM>, and the finger <NUM> extending between the legs <NUM> and in a direction approximately perpendicular to the legs <NUM>. The rod <NUM> extends through the recess <NUM> of the tool holder 30a and defines an axis of rotation <NUM> about which the handle 46a rotates with respect to the tool holder 30a. The rod <NUM> is cylindrical and has a recessed portion <NUM> defined between two edges <NUM>, <NUM> on the circumference of the rod <NUM>. Opposite the recess <NUM>, an arcuate portion <NUM> is defined between the two edges <NUM>, <NUM> along the circumference of the rod <NUM>. As shown in <FIG>, with respect to the axis of rotation <NUM>, the arcuate portion <NUM> defines an angle α that is slightly less than <NUM> degrees about the circumference of the rod <NUM>. Correspondingly, the recess <NUM> defines an angle β that is slightly more than <NUM> degrees.

If an operator elects to use chisel 34a with the tool holder 30a, rotation of the handle 46a to the first position causes rod <NUM> to rotate such that the arcuate portion <NUM> contacts the chisel 34a within the longitudinal groove <NUM>. Thus, if the operator tips the percussion tool <NUM> in such a manner that the chisel 34a might be caused to fall out of the tool holder 30a, the arcuate portion <NUM> will contact the rear end <NUM> of the longitudinal groove <NUM> to prevent the chisel 34a from falling out. During operation of the percussion tool <NUM>, as the striker <NUM> imparts axial blows to the chisel 34a along the longitudinal axis <NUM>, the chisel 34a reciprocates within the tool holder 30a between forward and rearward positions where the arcuate portion <NUM> is maintained between the rear end <NUM> of the longitudinal groove <NUM> and the front end <NUM> of the longitudinal groove <NUM>.

To release the chisel 34a, the operator must rotate the handle 46a from a first position (having an orientation relative to axis <NUM> similar to that shown in <FIG> and <FIG>) in which the arcuate portion <NUM> is located at least partially within the groove <NUM> of the chisel 34a to a second position shown in <FIG>. Rotation of the handle 46a to the second position causes the rod <NUM> to rotate, thus rotating the arcuate portion <NUM> away from the longitudinal groove <NUM> and removing the arcuate portion <NUM> from the longitudinal groove <NUM> of the chisel 34a, and instead placing the recessed portion <NUM> in facing relationship with the longitudinal groove <NUM>, thus allowing chisel 34a to be removed. As shown in <FIG>, an angle θ is defined between a first reference plane <NUM> defined by handle 46aand a second reference plane <NUM> that is perpendicular to the longitudinal axis <NUM>. In the embodiment of <FIG>, the angle θ is approximately <NUM> degrees. In the embodiment illustrated in <FIG>, the first reference plane <NUM> is defined as tangent to the finger <NUM>. In other embodiments, the first reference plane <NUM> could be defined as extending along the legs <NUM>, and the second reference plane <NUM> would be shifted left, as viewed in <FIG>. Regardless of where the reference plane <NUM> is defined on the handle 46a, if the handle 46a is rotated to a position intermediate the first and second positions, the first reference plane <NUM> would be co-planar with the second reference plane <NUM>.

<FIG> illustrates another embodiment of a tool holder 30b for use with the breaker <NUM> of <FIG>, with like components shown with like reference numerals. The tool holder 30b includes a handle 46b that is otherwise identical to the handle 46a except that the angle α defined by the arcuate portion <NUM> is approximately <NUM> degrees about the circumference of the rod <NUM>. Thus, the recessed portion <NUM> defines an angle β that is approximately <NUM> degrees. To release the chisel 34a, the operator must rotate the handle 46b from a first position (having an orientation relative to axis <NUM> similar to that shown in <FIG> and <FIG>) in which the arcuate portion <NUM> is located at least partially within the groove <NUM> of the chisel 34a to a second position shown in <FIG>. In this embodiment of the tool holder 30b, the angle θ defined between the finger <NUM> of handle 46b and the plane <NUM> is approximately <NUM> degrees. Because the arc length of the arcuate portion <NUM> has been reduced to approximately <NUM> degrees in the embodiment of <FIG>, the operator does not need to rotate the handle 46b as far as in the embodiment of the tool holder 30a shown in <FIG> to release the chisel 34a (<NUM> degrees beyond the second reference plane <NUM> with the tool holder 30a versus <NUM> degrees beyond the second reference plane <NUM> with the tool holder 30b). Such an arrangement makes it faster and easier for the operator to change the chisels 34a, 34b used in the tool holder 30b. In the embodiment illustrated in <FIG>, the first reference plane <NUM> is defined as tangent to the finger <NUM>. In other embodiments, the first reference plane <NUM> could be defined as extending along the legs <NUM>, and the second reference plane <NUM> would be shifted left, as viewed in <FIG>. Regardless of where the reference plane <NUM> is defined on the handle 46b, if the handle 46b were rotated to a position intermediate the first and second positions, the first reference plane <NUM> would be co-planar with the second reference plane <NUM>.

Claim 1:
A percussion tool (<NUM>) for performing a chiseling operation on a workpiece with a chisel (34a, 34b), the percussion tool comprising:
a housing (<NUM>);
an electric motor positioned within the housing;
a percussion mechanism (<NUM>) driven by the motor and including a striker (<NUM>) supported for reciprocation relative to the housing along a longitudinal axis (<NUM>); and
a tool holder (30b) coupled to the housing and including a rotatable handle (46b) having a rod (<NUM>) that rotates with the handle within the tool holder, the chisel being securable in and removable from the tool holder, the chisel having a longitudinal groove (<NUM>) that is substantially parallel with the longitudinal axis,
wherein when the chisel is secured in the tool holder, the chisel is permitted to axially reciprocate within the tool holder in response to receiving repeated axial impacts from the striker,
wherein the handle is moveable between a first position, in which the rod is received in the groove and the chisel is secured in the tool holder, and a second position, in which the rod is removed from the groove and the chisel is removable from the tool holder, characterised in that
when the handle is in the second position, an acute angle (Θ) is defined between a first reference plane (<NUM>) defined by the handle and a second reference plane (<NUM>) that is perpendicular to the longitudinal axis, and wherein the acute angle is <NUM> degrees or less.