Rotary tool with multiple tool attachment interfaces

A rotary tool has an output shaft having an axis of rotation and a distal neck portion which has at least three neck faces that do not intersect the axis of rotation, and a substantially U-shaped spring element having a base portion and two leg portions, wherein the spring element straddles the distal neck portion.

CROSS-REFERENCE TO RELATED APPLICATION

The invention described and claimed hereinbelow is also described in German Patent Applications EP 07117056.7 filed on Sep. 24, 2007. This European Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d).

BACKGROUND OF THE INVENTION

The present invention relates to rotary tools and in particular to interfaces for attaching different sorts of working members, such as driver bits or sockets, to the shaft of a rotary tool.

Patent application Ser. No. 10/155,574 discloses a hybrid interface that allows one to secure either a driver bit or a socket to rotary tool output shaft. The output shaft is configured to include a hexagonal cavity for receiving a driver bit along with means, such as a ball and sleeve arrangement, for attaching or releasing the bit. The distal end of the output shaft has a square-shaped periphery, and so it is also able to accommodate a typical socket. One embodiment is configured to cooperate with a pin and an O-ring to secure sockets according to a standard used in Japanese markets. A second embodiment employs a spring-loaded protrusion mounted to a hole on the periphery of the output shaft to secure sockets configured with an inner annular groove which is typical of the standard used in North American and European markets.

JP Patent Application No. 2004-190714 discloses a socket attachment interface intended to simplify the attachment of sockets according to the Japanese standard. A detachable spring member is secured with a screw to the end face of the output shaft of a rotary tool and includes one or more protrusions that cooperate with one or more through-holes in the socket.

Accordingly, it is an object of the present invention to provide a rotary tool which is a further improvement of existing rotary tools.

SUMMARY OF THE INVENTION

The present invention provides a hybrid tool attachment interface that incorporates advantages from both of the above-described designs and which can accommodate a driver bit as well as a variety of sockets. The design is simple to manufacture and assemble and does not require additional tools for mounting or removing bits or sockets.

The inventive rotary tool comprises an output shaft having an axis of rotation, a distal neck portion which has at least three neck faces that do not interest the axis of rotation and a generally U-shaped spring element having a base portion and two leg portions, wherein the spring element straddles the distal neck portion.

The U-shaped spring element is securely attached to the output shaft without any separate fastening means and has the advantage that features that can be used to secure multiple types of working members can be embodied in an inexpensively constructed part that is furthermore easily detachable should it be subject to wear or damage and need to be replaced.

The design has the advantage that the output shaft is provided with an elongate cavity coaxial with its axis of rotation, so that it can optionally receive a driver bit, thereby providing additional functionality for the user, who can select from either a driver bit or a socket without needing to use a separate adaptor.

The output shaft is further provided with means for securing a driver bit within the elongate cavity. Preferably these means comprise a slidably-mounted sleeve which is biased by a spring and which cooperates with balls which act as locking members when a driver bit with a circumferential groove is inserted. In this way, the user can easily remove or attach a driver bit of this type without any separate tools.

The spring element of the inventive rotary tool has two tip portions, each of which is contiguous with one of the two leg portions. These two tip portions together with the base portion and the two leg portions embrace the distal neck portion to retain the spring element. Hence the force of the spring and its geometry allow the spring plate to surround and fasten itself to the neck region of the output shaft without the need for separate fastening means. Since it is detachable, the user may optionally remove the spring element for replacement or use with certain tool types.

Each of the two leg portions contacts one of the neck faces of the distal neck portion and this serves to grip around the output shaft to retain the spring element. Preferably the leg portions contact the neck faces within recessed regions of the neck faces. This has the advantage that the spring plate can lie flush with the rest of the distal neck portion to provide an overall generally flat profile for insertion of a socket.

Adjoining the recessed faces of the distal neck portion are elevated portions that serve as stop surfaces. These stop surfaces provide the advantage that the spring plate is prohibited from moving axially along the axis of rotation when a socket is inserted onto or removed from the distal neck portion.

One of the means by which the spring plate retains a socket is by having at least one spring-elastic protrusion on a leg portion. Preferably two such protrusions are present on two leg portions. The protrusions can advantageously mate with either an internal groove or a radial cavity within a socket.

When a socket is inserted, it will generally deflect the spring-elastic protrusion as well as the portions of the spring plate, preferably arms, that surround the protrusion. Therefore it is advantageous to provide cavities extending from each neck face to the elongate cavity to receive each spring-elastic protrusion when they are deflected. It is preferable if there are multiple aspects to the cavity, an internal cylindrical aspect that can be used to mate with a pin inserted through the shaft and the socket, as well as a larger, and preferably conically shaped cavity portion. The larger, conically-shaped portion can accommodate the protrusion and the flexible arms surrounding the protrusion even when the protrusion is maximally deflected.

To allow the same attachment interface to accommodate sockets according to a Japanese standard wherein a pin and O-ring are used to secure the socket, the base portion of the spring element is provided with an opening. The opening is positioned generally coaxially with the cavity in the output shaft so they may cooperate to form an insertion pathway for the pin that is used to secure the socket.

Since protrusions for retaining a socket as well as a pathway for traversing the output shaft with a pin are provided at the same time, the inventive rotary tool can securely attach working members via at least three different means. First, a driver bit can be inserted and retained in the elongate cavity. Second, a socket with an internal groove can be retained via the spring-elastic protrusions. Third, a socket with a radial cavity can be retained not only via the spring-elastic protrusions, but also via cooperation with a pin which traverses an opening in the spring plate and a cavity in the output shaft, so that it can be secured by an O-ring extending around the perimeter of the socket.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An example of a rotary tool according to the present invention is illustrated inFIG. 1. While the illustrated embodiment is a power tool, and specifically a cordless impact driver, the invention may be advantageously used with a variety of rotary tools irrespective of whether they are powered or whether they include an impact driving function. Within housing10of rotary power tool12are a motor14and its associated motor shaft16. A transmission18converts the rotation of the motor shaft16into increased output torque, but correspondingly reduced speed rotation of the driveshaft20.

The driveshaft20is coupled to a hammer22which is in turn coupled to an output shaft24. The driveshaft20, hammer22and output shaft24are configured to transmit repetitive bursts of output torque via a hammer and anvil arrangement as is well known to those skilled in the art. An example of such an impact driver is shown in US 2006/0237205-A1, which is hereby incorporated by reference. The tool is provided with a handle26and a trigger28so that it may be conveniently operated by a user. The power source is a DC battery30in this exemplary cordless tool, but an AC power source is a standard alternative.

FIGS. 2-4show various views of a tool attachment interface for a rotary tool. The output shaft24has a proximal neck portion32, a distal neck portion34, an end face36, and an axis of rotation38. An elongate cavity40in the output shaft24is centered around the axis of rotation38. The cavity is preferably polygonally shaped so that it can accommodate a complementary polygonally-shaped driver bit (not shown).

As means for securing a driver bit, a sleeve44, a compression spring46, and a retaining ring48, are mounted around the proximal neck portion32of the output shaft24. All of these elements are secured to the proximal neck portion32once a C-ring50is inserted into annular groove52. The force from the spring46positions the sleeve44such that balls54mounted in radial cavities56are urged partially into the elongate cavity40to act as locking members to act on a hexagonal driver bit with an annular groove (e.g., according to the DIN 3126-E6.3 standard) so that it can be securely attached and released from the output shaft24.

The radial cavities56are sized with a variable diameter, such that the balls54may travel within the radial cavities56but can only protrude partially into elongate cavity40. A user can urge the sleeve44against the spring force, so that the balls have space enough to exit entirely from the elongate cavity40. Rather than ball pairs54, a single ball, an elongate pin, or a blade may alternatively be used as locking members.

Besides these preferred means for retaining a driver bit, many prior art alternatives are also compatible, so long as they can coexist with the socket-retaining means that will be further described. The essential features are that the output shaft24is configured with an elongate cavity40, and the means for securing the driver bit are located within or around the proximal neck portion32of the output shaft24. For example, one or more screws mounted perpendicular to the axis of rotation could also be used to secure the driver bit.

Alternatively, a magnetic part incorporated into the proximal neck portion32could be used to attract and retain the driver bit. Furthermore different methods of adjustment are possible. Instead of being biased by the spring46, the sleeve44could instead be threaded to the proximal neck portion32, so that its position is adjusted via rotation in order to correspondingly position the one or more locking members.

To accommodate sockets that have a square-shaped female interface, the distal neck portion34of the output shaft24is preferably square-shaped in a cross-section taken perpendicular to the axis of rotation38. Detailed features of the distal neck portion34are shown inFIGS. 4 and 5. Each of its four neck faces60is configured with a neck cavity62that traverses the space between the neck face60and the elongate cavity40and comprises a cylindrical portion64and a conical portion66. The surface of each neck face60is partially recessed. Each of four recessed faces70are linked by similarly recessed bevel faces69at the four corners of the distal neck portion34. Front67and rear68elevated portions are found on either side of the recessed faces70and bevel faces69.

Without any further elements attached, the distal neck portion34is sufficient to permit a user to mount and secure a Japanese-type socket71to the output shaft24using a metal pin72and a rubber O-ring74as retaining means as is customary for this standard (seeFIG. 6). To do so, a socket71is mounted onto the output shaft24such that each inner face76of the socket makes contact with elevated portions68of each neck face60. Then a pin72is inserted through radial cavities78in the socket and through two neck cavities62of the output shaft24. Finally, an O-ring74is mounted around an annular groove80of the socket71to trap the pin72.

Note that a given socket71can be mounted in any of four possible orientations relative to the output shaft24, resulting in the mounting pin72traversing the socket71in one of two possible orientations. In every case, there is no interference from the driver bit mounting means and therefore the two distinct mounting interfaces may coexist on the same output shaft24.

So that the output shaft24can also accommodate different types of sockets, and so that they may be retained without separate fastening members, a spring plate82comprising a base portion84, two leg portions86, two corner portions88, and two leg tip portions89is preferably mounted to the distal neck portion34of the output shaft24. Each of the two corner portions88link the base portion84with a leg portion86. Each of the two leg tip portions89extend from the end of the leg portion, that is, they extend from the part of the leg portion86opposite the part of the leg portion86that interfaces with the base portion84.

The spring plate82is best visualized in the exploded view ofFIG. 4. It is fastened to the output shaft24without any separate fastening means and does not require the use of tools for attaching or detaching. The cross section of the mounted spring plate82taken perpendicular to the axis of rotation38(not shown) is substantially U-shaped, as defined by the base portion84and the two leg portions86.

The thickness of the spring plate82corresponds very closely to the dimensions of the distal neck portion34, so that when the spring plate82is mounted, each of its portions contacts a recessed face70or a bevel face69, so that it is substantially but not necessarily exactly flush with the surface of the front67and rear68elevated portions of each neck face60(seeFIG. 5). These elevated portions67,68provide a stop surface to counter the axial force acting on the spring plate82when a socket is inserted or removed.

The two corner portions88and the two leg tip portions89of the spring plate82are complementary to the bevel faces69of the distal neck portion34. As each neck face60of the distal neck portion34is structurally equivalent, the spring plate82can be mounted in any of four possible orientations. The spring plate82exerts a spring force which tends to grip the distal neck portion34via its two leg tip portions69. It can be manually removed by overcoming this spring force. The distal neck portion34may alternatively have an asymmetrical design, for example with only two neck cavities62. In this case, the spring plate82is preferably inserted in particular orientations.

While the spring force itself comprises sufficient attachment means for retaining the spring plate82, alternatives are possible. If the spring plate82were provided with an opening on one of its faces that corresponded to a cavity on the distal neck portion34, the parts could be secured with a screw or the like. A suitable screw head would be flat and its head preferably somewhat recessed within the spring plate82so as not to interfere with the insertion of a socket. In addition, such a screw should not be long enough to enter the elongate cavity40so as to interfere with the mounting of a driver bit.

At the center of each leg portion86of the spring plate82there is a spring-elastic protrusion90. Four openings92surround the protrusion, thereby establishing four flexible arms94. Although not absolutely essential features of the spring plate, these openings92and arms94reduce the force necessary to deflect a protrusion90below the surface of the leg portion86. As will be seen below, this may potentially happen during the insertion of a socket onto the attachment interface. Therefore, a leg portion86with two, three, five, six or even more openings can be used towards this same goal and present reasonable alternatives. The spring plate82is preferably manufactured through stamping of sheet metal and these openings92and arms94can be readily introduced during this process.

When it is deflected, each protrusion90exerts a radial force generally perpendicular to the axis of rotation38. When a socket71is inserted, its inner face76deflects each protrusion90while the socket71slides into its mounting position, at which time the protrusion90acts on a cavity78or groove100in the socket71. When the spring plate82is mounted to the output shaft24, the position of each protrusion90and flexible arm94corresponds roughly to the position of the cylindrical portion64and conical portion66of the neck cavity62respectively. This structure provides sufficient space for the protrusion90and flexible arms94to be deflected in the general direction of the axis of rotation38against its inherent spring force.

The base portion84of the spring plate82has an opening96roughly comparable in diameter to that of the cylindrical portion64of a neck cavity62. Since the opening96is positioned coaxially with the neck cavity, a pin72can be inserted through these features so that a socket71can be mounted using a pin72and O-ring74even when the spring plate82is mounted to the output shaft24. In this configuration, the inner faces76of the socket71constantly deflect the protrusions90, but this is permissible since there is adequate space in the neck cavity92to accommodate the protrusions90as described above. Alternatively and preferably, the same socket71could be removed, rotated ninety degrees, and inserted past the spring force of the protrusions90, so that each protrusion90engages with a radial cavity78in the socket71as shown inFIG. 7. A socket98with an internal annular groove100is also retained by this attachment interface as shown inFIG. 8.

While the invention has been illustrated and described as embodied in a rotary tool with multiple tool attachment interfaces, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.