Interchangeable implement system for power tools

[0002] The benefit of priority under 35 U.S.C. § 119(e) is claimed based on U.S. Provisional Application Ser. No. 60/094,082, filed Jul. 24, 1998.

[0003] 1. Field of the Invention

[0004] The present invention is directed to power tools. In particular, the present invention is directed to a power tool having a system of detachable and interchangeable implements. The term “power tool” includes hand-held power tools such as hedge trimmers and chain saws, as well as mechanisms which are not hand-held but whose operation is controlled by the hands of a user, e.g., lawn mowers and grinders.

[0005] 2. Description of Related Art

[0006] In order to perform a desired task using a power tool, it is important to select a power tool that has the proper configuration and capacity for accomplishing the task efficiently and safely. The size and shape of the working tool, the speed and power of the driving mechanism, as well as the comfort and safety of the user must always be considered.

[0007] Conventionally, a user selects the appropriate tool from a collection of similar devices each having different characteristics. For example, in order to select an appropriate hand-held, powered hedge trimmer, the user must make a number of choices: whether to use a single or a double edge cutting blade, the length of the cutting blade, the shape of the cutting teeth, whether driving power should come from an electric motor or an internal combustion engine, the amount of power and speed required for driving the cutting blade, etc. Given all the permutations of these characteristics, a large collection of variously configured hedge trimmers would be required. Generally, the cost of purchasing, maintaining and storing such a large collection of hedge trimmers is prohibitive.

[0008] It is much more common for a user to own a single hedge trimmer that is used in every situation, regardless of how well suited the hedge trimmer is to that particular situation. Under these circumstances, the efficiency and/or adequacy of the tool is often insufficient.

[0009] It is also conventional for a power tool to be of fixed configuration. Specifically, it is common for each tool to have a single relative arrangement of the handle, power source and working tool. One disadvantage of such a fixed arrangement is that the user is not able to adjust the power tool for safe and comfortable operation.

[0010] It is an object of the present invention to overcome these disadvantages of conventional power tools.

[0011] It is another object of the present invention to provide a power tool that may be readily selectively configured by the user for optimum efficiency, as well as ease and safety of operation.

[0012] It is yet another object of the present invention to provide an arrangement for mating a driving source with a detachable working implement selected from a range of interchangeable tools.

[0013] It is a further object of the present invention to provide a mating arrangement for connecting a driving source with a detachable working implement that does not require additional tools to make the connection.

[0014] It is yet a further object of the present invention to provide an arrangement for interchangeably supporting a working implement with respect to a driving source, and for transferring power from the driving source to the working implement.

[0015] The objects of the present invention are achieved by means of an attachment system for connecting a driven implement to a driving source including a power take-off accessible with respect to a main body. The attachment system comprises a housing adapted for supporting the driven implement and for matingly engaging the main body; a drive transfer adapted for matingly connecting the power take-off to the driven implement; and an implement mount adapted for supporting the driven implement for movement with respect to the housing.

[0016] The objects of the present invention are also achieved by means of a hand held power tool having at least one interchangeable implement. The power tool comprises a generally hollow main body having an exterior surface; a bale handle connected to the main body and adapted for gripping by the hand, the bale handle being pivotally mounted with respect to the exterior surface; a driving source being supported inside the main body and adapted for outputting mechanical energy; a power take-off transferring the mechanical energy outside the main body; a housing matingly engaging the main body in a first position, the housing adapted for supporting the implement; and a drive transfer operatively connecting the power take-off to the implement. The housing is detachably separable from the main body.

[0017] The objects of the present invention are further achieved by means of a power tool system for trimming hedges. The power tool system comprises a main body at least partially enclosing a driving source; a first housing adapted for mating engagement with respect to the main body, the first housing including a first set of relatively reciprocating blades adapted for being operatively driven by the driving source; and a second housing adapted for mating engagement with respect to the main body, the second housing including a second set of relatively reciprocating blades adapted for being operatively driven by the driving source. The first and second housings are interchangeably connectable with respect to the main body.

[0018] The objects of the present invention are yet further achieved by means of a latch arrangement for securing a housing with respect to a main body. The latch arrangement comprises at least one arm adapted for pivotal movement with respect to the main body about a pivot axis; a grip adapted for grasping to pivot the at least one arm, the grip being fixed to the at least one arm; and a cam surface on each of the at least one arm, the cam surface being adapted for biasing the housing toward the main body. The at least one arm is elastically deformed by engagement between the cam surface on each of the at least one arm and the housing.

[0019] The objects of the present invention are additionally achieved by means of a handle adjustment system. The handle adjustment system comprises a main body having an exterior surface; and a bale handle connected to the main body and adapted for gripping by the hand, the bale handle being pivotally mounted with respect to the exterior surface. A first one of the exterior surface and the bale handle includes at least one projection engaging at least one recess formed in a second one of the exterior surface and the bale handle, whereby cooperative engagement between one of the at least one projection and one of the at least one recess define a detent adapted for maintaining the bale handle at a pivotal position with respect to the main body.

[0020] The objects of the present invention are yet additionally achieved by means of an interchangeable implement for connecting to a driving source including a power take-off accessible with respect to a main body. The interchangeable implement comprises a housing adapted for supporting a driven implement and adapted for matingly engaging the main body; two female members being formed in the housing and adapted to matingly receive a corresponding male member extending from the main body, each of the female members having a mating diameter in a range of 4 to 8 millimeters and being spaced apart a center-to-center distance in a range of 50 to 70 millimeters; and two projections extending from opposite sides of the housing, each of the two projections supporting a respective roller extending at least 2 millimeters from a respective one of the opposite sides to an enlarged shoulder, and a shoulder-to-shoulder measure between the enlarged shoulders being in a range of 80 to 110 millimeters.

[0021] Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be readily apparent to those skilled in the art from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

[0022] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a presently preferred embodiment of the invention, and, together with the general description given above and the detailed description of the preferred embodiment given below, serve to explain the principles of the invention.

[0023] FIG. 1 is a schematic illustration of a power tool according to the present invention having a main body matingly engaging a housing of a working implement, and a latch assembly in a first, unlatched, position.

[0024] FIG. 2 is a schematic illustration of the power tool shown in FIG. 1, with the latch assembly in a second, latched, position.

[0025] FIG. 3 is a perspective view of the latch assembly shown in FIG. 1.

[0026] FIG. 4 is a perspective view of a gear case portion of the power tool main body according to the present invention.

[0027] FIG. 5 is a perspective view of a working implement according to the present invention.

[0028] FIG. 6 is an exploded view of the working implement shown in FIG. 5.

[0029] FIGS. 7A and 7B are perspective views of an auxiliary handle for a power tool according to the present invention.

[0030] FIG. 8 is a perspective view of a detail of a main body of a power tool according to the present invention.

[0031] FIG. 9 is a partial cross-section view of a power tool according to a preferred embodiment of the present invention.

[0032] FIG. 10 is a bottom plan view of a main body of the preferred embodiment of the present invention illustrated in FIG. 9.

[0033] FIG. 11 is a detail view of a clutch hub according to the preferred embodiment of the present invention illustrated in FIG. 9.

[0034] FIG. 12 is a side elevation view of a working implement according to a preferred embodiment of the present invention.

[0035] FIG. 13 is a top plan view of the working implement according to the preferred embodiment of the present invention illustrated in FIG. 12.

[0036] FIG. 14 is a cross-section view taken along line XIV—XIV in FIG. 13.

[0037] FIG. 15 is a detail view of a drive spud according to the preferred embodiment of the present invention illustrated in FIG. 12.

[0038] A hand-held power tool 1 is shown in FIGS. 1 and 2. The power tool 1 includes a main body 10 supporting and enclosing a driving source such as an electric motor or an internal combustion engine (not shown). The main body 10 additionally supports conventional controls and auxiliary systems (not shown) for operating the driving source. The main body 10 also provides at least one means for a user's hands to hold the power tool 1.

[0039] A working implement 14 is operably connected to the driving source. For the sake of illustration, a double edge hedge-trimming implement is generically illustrated throughout the drawings. However, in accordance with the present invention, implements of different types and/or characteristics may also be used in connection with the main body 10. One example of a different type of implement is a rotary saw, as opposed to a reciprocating saw.

[0040] A housing or cassette 16 connects the implement 14 to the main body 10. The cassette 16 provides a physical connection for supporting the mass of the implement 14 with respect to the main body 10, as well as houses a driving connection between the driving source and the implement 14.

[0041] The connection between the cassette 16 and the main body 10 provides a detachable interface such that different types and/or sizes of working implements may be readily connected to the main body 10 by different cassettes 16. Specifically, the cassette 16 provides a single type of connection for attaching a range of implements having different characteristics (e.g., type, size, etc.) to the same main body 10. Similarly, the cassette 16 enables the implement 14 to be connected to a range of main bodies 10 having different characteristics (e.g., driving source type, power output, etc.).

[0042] According to the present invention, a large collection of power tools is provided by interchangeably connecting small numbers of main bodies 10 and cassettes 16. Thus, a user is able to select the appropriate power tool for a desired task without the expense of purchasing, maintaining and storing a wide range of individual power tools.

[0043] According to a preferred embodiment of the present invention, as illustrated in FIGS. 1-3, a latch assembly 18 is used to secure and release the cassette 16 with respect to the main body 10. The latch assembly 18 is pivotally mounted with respect to the gear case 12 at a pair of pivot points 20A and 20B on opposite sides of the gear case 12. Spacers 19, see FIG. 1, are interposed between the latch assembly 18 and a pair of bosses 20 (only one shown) formed on the opposite sides of the gear case 12. This provides electrical insulation for the latch assembly 18 from the gear case 12, drive mechanism, and blades 50A,50B in the event the insulation of the power cord (for an electric powered version) is severed accidentally while operating the power tool 1. The spacers 19, which are preferably made of plastic, also provide a durable, low friction bearing surface for the latch assembly 18 to pivot on, as opposed to having the latches wearing into the bosses 20 on the gear case 12 when pivoted. The latch assembly 18 includes a pair of latch arms 22A and 22B extending substantially parallel to one another and transversely from a common grip 24 to a corresponding one of the pivot points 20A,20B. According to the preferred embodiment of the present invention, each of the pivot points 20 comprises one of the two bosses 20A′,20B′ on the gear case 12, respectively, and one of two holes 20A″ and 20B″, respectively, on the latch arms 22A,22B. Although the bosses 20 are shown formed on the gear case 12 and the holes 20A″,20B″ are shown formed in the latch arms 22A,22B, the bosses 20 may alternatively be formed on the latch arms 22A,22B and the holes 20A″,20B″ formed in the gear case 12.

[0044] The latch arms 22A,22B include respective cam surfaces 26A and 26B for engaging corresponding rollers 28A and 28B mounted for rotation about posts on opposite sides of the cassette 16. The cam surfaces 26A,26B and the rollers 28A,28B comprise overcenter mechanisms such that as the latch assembly 18 is elastically deformed during pivoting with respect to the gear case 12. Specifically, as the latch assembly 18 is pivoted from a relaxed (i.e., un-deformed) state to a first position, the cam surfaces 26A,26B engage the rollers 28A,28B so as to elastically elongate that portion of the latch arms 22A,22B extending from the pivot points 20A,20B to the cam surfaces 26A,26B. Upon further pivoting the latch assembly 18 to a second position, the cam surfaces 26A,26B remain engaged with the rollers 28A,28B; however, the latch arms 22A,22B are elongated to a lesser degree. As is known with overcenter mechanisms, the latch arms 22A,22B tend to be biased away from the first position of greatest elongation to either the second position of reduced elongation, or to a third position wherein the latch arms 22A,22B are in the relaxed state. Thus, the latch assembly 18 secures and releases the cassette 16 with respect to the gear case 12 simply by pivoting the latch assembly 18 with respect to the gear case 12, i.e., without the need of any additional tools or fasteners. By virtue of the grip 24 being spaced apart from the pivot points 20A,20B a greater distance than the cam surfaces 26A,26B are spaced apart from the pivot points 20A,20B, a mechanical advantage is realized.

[0045] FIG. 4 shows the surface of the gear case 12 that interfaces with the cassette 16. In a preferred embodiment of the present invention, a first clutch part, or clutch hub, 30 is driven by the driving source and is accessible from the exterior of the gear case 12. The clutch hub 30 provides a driving force that is transferred through the cassette 16 to operate the implement 14. Also projecting from the gear case 12 are positioning pins 32A and 32B for locating the cassette 16 with respect to the gear case 12. As will be described further with reference to FIG. 5, the pins 32A,32B are received in corresponding holes in the cassette's cover plate 40. Although the pins 32A and 32B are shown as part of the gear case 12 and the holes are shown as part of the cassette 16, the pins may alternatively be attached in the cassette 16, and the holes formed in the gear case 12.

[0046] FIG. 5 shows the surface of the cover plate 40 that interfaces with the gear case 12. The pins 32A,32B are matingly received in holes 34A and 34B, and the clutch hub 30 matingly engages a second clutch part, or drive spud, 72).

[0047] FIGS. 5 and 6 show a preferred embodiment of the present invention having a cassette 16 for connecting a reciprocating, double edge hedge trimming implement 14 to the gear case 12. The cassette 16 includes a shell 38 and the cover plate 40, and defines an interior volume. The shell 38 supports the mass of the implement 14 that is retained by means of two fasteners 42A and 42B and two nuts 48A and 48B secured to a clamping plate 46, which is trapped between the shell 38 and the cover plate 40. Anti-friction washers 44A and 44B are interposed between respective ones of the fasteners 42A,42B and the blades 50A,50B for improving the relative sliding action and reducing wear of the implement 14 with respect to the cassette 16. Different clamping plates 46, fasteners 42A,42B, and nuts 48A,48B may be used to support implements 14 having different characteristics within the housing 16.

[0048] According to the preferred embodiment of the present invention, the implement 14 includes two stacked blades 50A and 50B that are longitudinally reciprocated with respect to one another. A blade support 52 extends along the length of the blades 50A,50B to maintain the relative relationship between the blades 50A,50B at the distal end thereof. The blades 50A,50B and blade support 52 operate in a conventional manner. The blades 50A,50B and the blade support 52 are interposed between the clamping plate 46 and the shell 38, and extend outward from the interior of the cassette 16 through an opening between the shell 38 and the cover plate 40. The relative configuration of the clamping plate 46 with respect to both the implement 14 and the cassette 16 ensures only the desired relative motion of the implement 14 with respect to the housing 16.

[0049] Also mounted in the interior of the shell 38 is the drive spud 72 for matingly engaging the clutch hub 30 and for transferring motion from the clutch hub 30 to the blades 50A,50B. According to the preferred embodiment of the present invention, the drive spud 72 engages a blade driver (not shown) that is rotates about the same axis of rotation as the clutch hub 30 and the drive spud 72. The blade driver includes eccentrics (not shown) that matingly engage the blades 50A,50B in a conventional manner for reciprocating the blades 50A,50B with respect to one another. The drive spud 72 may also include a bearing 55 for reducing heat and wear. The drive spud 72, clutch hub 30, blade driver, and the eccentrics may all also be made of a material capable of acting as its own bearing surface.

[0050] The cover plate 40 includes the aperture 36 for the drive spud 72 to protrude from to engage the clutch hub 30, as well as the holes 34A,34B for receiving the positioning pins 32A,32B.

[0051] When the cassette 16 is to be engaged with the gear case 12, the pins 32A,32B are aligned with the holes to prevent relative lateral movement between the cassette 16 and the gear case 12 The latch assembly 18 is subsequently pivoted to the second position described above to hold the cassette 16 against the gear case 12. Concurrently, the drive spud 72 passes through the aperture 36 and matingly engages the clutch hub 30 for conveying movement from the driving source, through the cassette 16, to the implement 14. The reverse procedure is used for disconnecting the cassette 16 from the gear case 12.

[0052] According the present invention, a common interface between cassette 16 and gear case 12 enables a wide range of implements 14 and main bodies 10 to be interchangeably connected.

[0053] According to another aspect of the present invention as shown in FIGS. 7 and 8, a bale handle 60 may be adjustably attached to the main body 10. The adjustable bale handle 60 enables a user to hold the power tool 1 comfortably and safely after interchanging the implements 14 or after the user repositions themselves with respect to the workpiece.

[0054] According to a preferred embodiment of the present invention, the bale handle 60 is fastened to the main body 10 for pivotal movement about an axis. A detent system comprising at least one projection 62 and at least one recess 64 are matingly engageable for holding the bale handle 60 at a desired angular position with respect to the main body 10. According to the preferred embodiment illustrated in FIGS. 7 and 8, the bale handle 60 includes a plurality of the projections 62′ and recesses 64′ arranged so as to at least partially circumscribe the pivot axis, and the main body 10 includes a plurality of the recesses 64″ (for engaging projections 62′) and projections 62″ (for engaging recesses 64′) arranged so as to at least partially circumscribe the pivot axis. For each position of the bale handle 60 relative to the main body 10, at least one of the projections 62′,62″ is matingly received in one of the recesses 64′,64″, respectively. Elastically deforming the bale handle 60 so as to displace the projections 62 in a direction parallel to the axis and away from the recesses 64 enables the bale handle 60 to be angularly reoriented. Aligning and matingly engaging a different combination of the projections 62 with recesses 64 enables the bale handle 60 to be retained at a different angular position with respect to the main body 10.

[0055] A lock may be used to releasably secure the detent system. According to a preferred embodiment, the lock may comprise cooperatively engaging threaded male and female members that, when relatively tightened, hold the projections 62 in the recesses 64.

[0056] According to a preferred embodiment, the range of angular adjustment of the bale handle 60 with respect to the main body 10 is constrained by at least one stop 66 that extends axially from the main body 10 into at least one arcuate groove 68 in the bale handle 60. The arcuate groove 68 partially circumscribes the pivot axis. The location and length of the arcuate groove 68 defines the permissible range of motion for the bale handle 60 relative to the main body 10.

[0057] Although the projections 62 have been illustrated as being formed on the bale handle 60, and the recesses 64 have been illustrated as being formed on the main body 10, it is alternatively envisioned that the projections 62 may be formed on the main body 10 and the recesses 64 may be formed on the bale handle 60. Similarly, although the stop 66 has been illustrated as being formed on the main body 10 and the arcuate groove 68 has been illustrated as being formed on the bale handle 60, it is alternatively envisioned that the stop 66 may be formed on the bale handle 60 and the arcuate recess may be formed on the main body 10.

[0058] FIGS. 9-15 are directed to a preferred embodiment of the present invention. According to this preferred embodiment, a driving force is transmitted through the clutch hub 30 and the drive spud 72. The clutch hub 30 and the drive spud 72 are configured and arranged to cooperatively engage one another, thus facilitating transmission of the driving force from the main body 10 to the implement 14.

[0059] The dimensions according to preferred embodiments of the present invention are indicated with on the Figures and correspond with the reference numerals in Table 1.

[0060] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices, shown and described herein. Accordingly, various modifications may be made without departing from the spirit and scope of the general inventive concept as defined by the appended claims and their equivalents.