Tool with composite housing

Abstract

A power tool includes a tool housing and a mechanism disposed within the tool housing. The tool housing has a composite structure including an outer layer and an inner layer. The outer layer provides an outer surface of the power tool housing and includes a first material. The outer layer is an assembly of concave housing portions joined along a parting line. The inner layer is disposed on an inner surface of at least a portion of the outer layer so as to be disposed between the portion of the outer layer and the mechanism. The inner layer includes a second material. A density of the first material is at least three times a density of the second material. The inner layer has a peripheral edge that is offset relative to the parting line such that the inner layer extends continuously across the parting line.

Description

BACKGROUND

[0001] Power tools, including hand-held, bench, and cabinet tools, employ structural housings that perform a variety of functions, including providing impact protection for all internal mechanical and electrical components, supporting internal mechanisms and motors, providing insulation isolation, and providing thermal isolation and thermal management features. In addition, the housings create the necessary ergonomic interface for the user, protecting the user from moving parts, and creating a protective structure in the case of proper flame ratings.

[0002] Some conventional power tools employ a molded plastic housing that provides a structural enclosure around the working mechanism. The thickness of the enclosure, in some cases combined with reinforcing ribs, provides the housing that performs the above functions.

[0003] In one example, a housing for a hand-held power tool can include a structural enclosure that is a monolithic element with a near-constant wall thickness. In some cases, a thermoplastic elastomer (TPE), such as styrene-ethylene-butylene-styrene (SEBSJ), or other suitable material, can be overmolded onto the outer surface of the enclosure to provide improved tactile grip (e.g., "soft grip") and user ergonomics, but with minimal impact on the structural integrity of the tool housing. The interior cavity of the housing contains a rib structure that reinforces the enclosure and provides mechanical support for the motor, gearbox, switches, electronics, battery, etc. When the tool has a substantial weight (e.g., greater than 4 pounds), the wall thickness and number of ribs are increased to withstand the forces of the user and impact forces from rough terrain use and impact loads due to inadvertent drops. In addition to increasing the weight of the tool, the rib structure has the undesirable characteristic of creating concentrated load paths to the underlying mechanisms. Any impact loads are only slightly reduced by the outer enclosure and ribs before they reach the mechanisms.

[0004] For cordless tools, the battery adds to the overall tool gross weight. This problem becomes more critical as larger and higher output batteries are used, as the battery takes a larger percentage of the tool gross weight. This creates an undesirable progression of further increasing the wall thickness and adding more internal ribs to increase the housing stiffness and maintain the required durability. Even with optimization techniques, the housing walls and ribs become quite large and result in undesirable external dishing marks and a heavier and more expensive housing. SUMMARY

[0005] In some aspects, a power tool includes a tool housing having a composite housing structure that significantly improves durability and efficiently manages impact energy during impact loading. In a power tool housing, a conventional rigid outer shell is replaced by a composite structure that uses two different material layers to produce controlled deformation and manage impact energy. The outer composite layer is thinner than a conventional (non-composite) housing for the same tool and is formed from a more compliant material designed for controlled deformation without cracking. The inner composite layer supports the outer layer and is either a rigid or flexible polymer foam.

[0006] Advantageously, the composite housing provides a significant weight reduction benefit. Since the wall thickness of the outer shell is reduced relative to some conventional tool housings to produce a durable structure, the weight of the overall tool is immediately reduced. Since all or most of the internal ribs can be replaced by a continuous or nearly continuous foam structure, the weight of the tool is further reduced. This construction is well suited for lightweighting and cost-effective energy management of power tool housings.

[0007] Further advantageously, for hand-held tools, it is understood that the composite structure produces a more durable structure. For larger non-hand-held power tools, such as table saws, the composite structure produces an important structural element. In the case of a table saw, the main housing becomes a large box feature that reinforces the structure and increases the rigidity of the tool. Additionally, the polymer foam layer facilitates the attachment of metal and non-foam elements during the molding process.

[0008] In some aspects, a power tool includes a tool housing and a mechanism disposed within the tool housing. The tool housing includes an outer layer that provides an outer surface of the power tool housing. The outer layer is composed of a first material. The tool housing includes an inner layer disposed on an inner surface of at least a portion of the outer layer. The inner layer is composed of a second material. A density of the first material is at least three times a density of the second material.

[0009] In some embodiments, the outer layer is an assembly of a concave first housing portion and a concave second housing portion, the first housing portion is joined together with the second housing segment along a first parting line to provide an enclosed interior space that houses the mechanism, the inner layer is disposed between the portion of the outer layer and the mechanism, and the inner layer has a first peripheral edge portion that is offset relative to the first parting line such that the inner layer continuously extends across the first parting line.

[0010] In some embodiments, the outer layer is an assembly of a first housing portion, a second housing portion, and a concave third housing portion, the third housing portion is joined together with the first housing portion and the second housing along a second parting line to provide an enclosed interior space that houses the mechanism, and the inner layer has a second peripheral edge portion that is offset relative to the second parting line such that the inner layer continuously extends across the second parting line.

[0011] In some embodiments, the inner layer is an assembly of a first inner layer portion and a second inner layer portion, the first inner layer portion abutting the second inner layer portion along a third split line, and the third split line is spaced apart from the second split line.

[0012] In some embodiments, the inner layer is positioned beneath the outer layer such that an outwardly facing surface of the inner layer faces an inwardly facing surface of the outer layer without any intervening structure, and the inner layer is not adhered and bonded to the outer layer.

[0013] In some embodiments, the inwardly facing surface of the outer layer is free of structural reinforcement protrusions at locations facing the inner layer.

[0014] In some embodiments, the outer layer has a non-uniform thickness such that the outer layer has a first thickness in a first region of the tool housing and a second thickness in a second region of the tool housing, the first thickness is less than the second thickness, and the inner layer is disposed on the inner surface of the outer layer within the first region of the tool housing.

[0015] In some embodiments, the power tool is a hand-held fastener driving tool including a mechanism disposed at a first end of a tool housing, the mechanism including a fastener driving mechanism. The tool also includes a power source disposed at a second end of the tool housing; and a handle extending between the first end and the second end. The first region of the tool housing includes the first end, and the second region of the tool housing includes the handle.

[0016] In some embodiments, the power tool housing includes a cabinet portion housing a mechanism, a planar work surface supported on the cabinet portion, and a support member configured to support the cabinet portion relative to an external support surface. The first region of the tool housing corresponds to the cabinet, and the second region of the tool housing corresponds to the support member.

[0017] In some embodiments, the first material is a thermoplastic polymer, and the second material is a polymer foam.

[0018] In some embodiments, the inner layer has a thickness that is at least 1.5 times a thickness of the outer layer.

[0019] In some aspects, a power tool includes a tool housing and a mechanism disposed within the tool housing. The tool housing includes an outer layer providing an outer surface of the power tool housing and an inner layer disposed on an inner surface of at least a portion of the outer layer. The outer layer is an assembly of a first outer housing portion and a second outer housing portion. The first outer housing portion is joined together with the second outer housing portion along a first split line to provide an enclosed interior space housing the mechanism. The inner layer is disposed between the portion of the outer layer and the mechanism. Additionally, the inner layer has a first peripheral edge portion offset relative to the first split line such that the inner layer continuously extends across the first split line.

[0020] In some embodiments, the outer layer comprises a first material, the inner layer comprises a second material, and the density of the first material is at least three times the density of the second material.

[0021] In some embodiments, the outer layer is an assembly of a first housing portion, a second housing portion, and a concave third housing portion. The third housing portion is joined together with the first housing portion and the second housing portion along a second part line to provide the enclosed interior space, and the second peripheral edge portion of the inner layer is offset relative to the second part line such that the inner layer extends continuously across the second part line.

[0022] In some embodiments, the inner layer is an assembly of a first inner layer portion and a second inner layer portion. The first inner layer portion abuts the second inner layer portion along a third part line, and the third part line is spaced apart from the second part line.

[0023] In some embodiments, the inner layer is positioned beneath the outer layer such that an outward-facing surface of the inner layer faces an inward-facing surface of the outer layer without any intervening structure, and the inner layer is not adhered and bonded to the outer layer.

[0024] In some embodiments, the outer layer has a non-uniform thickness such that the outer layer has a first thickness in a first region of the tool housing and a second thickness in a second region of the tool housing. The first thickness is less than the second thickness, and the inner layer is disposed on an inner surface of the outer layer within the first region of the tool housing.

[0025] In some embodiments, the power tool is a hand-held fastener driving tool that includes a mechanism disposed at a first end of the tool housing. The mechanism includes a fastener driving mechanism. The tool also includes a power source disposed at a second end of the tool housing and a handle extending between the first end and the second end. The first region of the tool housing includes the first end, and the second region of the tool housing includes the handle. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a side cross-sectional view of a wireless hand-held linear fastener driving tool including a composite housing as seen along line 1-1 of Figure 2

[0027] Figure 2 is a perspective view of the composite housing of the linear fastener driving tool of Figure 1

[0028] Figure 3 is a perspective cross-sectional view of the linear fastener driving tool of Figure 2 Figure 1 and wherein some non-housing elements of the tool are omitted to allow clear visualization of the composite housing.

[0029] ​​​Figure 4 is a replica of Figure 2 illustrating the position of the reference planes PI, P2 and P3 relative to the composite housing.

[0030] Figure 5 is a replica of Figure 1 the composite housing of

[0031] Figure 6 is a replica of Figure 1 the composite housing of

[0032] Figure 7 is a perspective view of the assembled inner layer of the housing as seen from the bottom and front of the tool.

[0033] Figure 8 is a perspective view of the assembled inner layer of the housing as seen from the top and front of the tool.

[0034] Figure 9 is a perspective view of the assembled inner layer of the housing as seen from the bottom and rear of the tool.

[0035] Figure 10 is an exploded view of the inner layer of the housing of Figure 9

[0036] Figure 11 is a perspective view of the composite housing of an alternative embodiment power tool.

[0037] Figure 12 is a perspective view of the composite housing of Figure 11 as seen along line B-B and shown with the workbench portion of the housing omitted to allow clear visualization of the composite housing. DETAILED DESCRIPTION

[0038] Referring to Figures 1-4 , the power tool 1 includes a tool housing 2 that is a composite of an outer layer 60 of a first material and an inner layer 80 of a second material, where the first material is different than the second material. By employing the two-layer composite structure described herein, the tool housing 2 allows for controlled deformation and manages impact energy in the event that the tool housing 2 experiences an impact, such as due to a drop or something falling on it. As discussed in detail below, due to the novel structure, the composite tool housing 2 is lighter in weight and more durable than some conventional tool housings.

[0039] ​The directions referred to herein, such as up, down, front (see reference numeral 50), back (see reference numeral 52), top (see reference numeral 54), bottom (see reference numeral 56), forward, rearward, upper, lower, etc., are used with respect to the orientation of the tool 1 as shown in FIG. 1 and are not intended to be limiting, as the tool 1 can be used in other orientations in space without departing from the principles of the present invention. Figure 1 The directions referred to herein, such as up, down, front (see reference numeral 50), back (see reference numeral 52), top (see reference numeral 54), bottom (see reference numeral 56), forward, rearward, upper, lower, etc., are used with respect to the orientation of the tool 1 as shown in FIG. 1 and are not intended to be limiting, as the tool 1 can be used in other orientations in space without departing from the principles of the present invention.

[0040] In the illustrated embodiment, the power tool 1 is a hand-held linear fastener driving tool, such as a gas nailer, designed to linearly drive fasteners, such as nails and staples. The power tool 1 includes a fastener driving mechanism 32, a fastener driving reset mechanism 40, a fastener feed mechanism 20, and a fastener magazine 21. In addition, the power tool 1 includes a removable battery pack 12. The fastener driving mechanism 32 includes a cylinder 33 and a piston (not shown) that is movable within the cylinder 33 along an axis that extends between the top 54 and the bottom 56 of the tool housing 2. The fastener driving mechanism 32 includes a gas reservoir 39 that is in communication with the cylinder 33 and contains a fixed volume of non-combustible gas. A blade 42 protrudes from the piston so as to extend out of the cylinder 33. The fastener driving reset mechanism 40 lifts the piston and compresses the gas within the reservoir 39 to a high pressure. This configuration corresponds to a "ready to fire" state of the power tool 1. When the user pulls the trigger 18 (e.g., "firing the tool"), the motor 34 rotates, thereby releasing the piston and the blade 42. The compressed gas within the cylinder 33 expands and drives the piston within the tool housing 2, whereby the blade 42 advances from the tool housing 2 with a drive stroke. While advancing, the blade 42 receives a fastener from the fastener feed mechanism 20 and pushes the fastener into a workpiece. Upon completion of the drive stroke, the lifting mechanism 40 returns the piston and the blade 42, thereby compressing the fixed volume of gas to a higher pressure in preparation for a subsequent nailing operation.

[0041] The fastener driving mechanism 32 is disposed in a main housing section 90 of the tool housing 2 at the front 50 of the power tool 1, and the removable battery pack 12 is connected to a battery connection section 92 of the tool housing 2 at the back 52 of the power tool 1. The fastener driving reset mechanism 40 is disposed in the main housing section 90 so as to be located below the fastener driving mechanism 32 along the front 50 of the power tool 1. The power tool 1 includes a fastener exit portion 10 and a guide body 11 that protrudes from the tool housing 2 below the fastener driving reset mechanism 40.

[0042] The tool housing 2 includes a grip section or handle 94 that serves as a hand grip and extends between the main housing portion 90 and the battery connection section 92. In this configuration, the handle 94 forms an upper, middle portion of the tool housing 2. The handle 94 is hollow and the trigger switch 16 is disposed in the handle 94. The trigger switch 16 is actuated by a trigger 18 that protrudes from a bottom facing surface of the handle 94. As can be seen from Figure 1 the handle 94 is designed to be gripped by a human hand and the trigger 18 is designed to be actuated by a user's fingers while gripping the handle 94.

[0043] The power tool 1 includes a printed circuit board 14 disposed in an interior space of the battery connection section 92. The printed circuit board 14 supports a controller (not shown). The trigger switch 16 and other devices provide input to the controller. The controller can include a microprocessor or microcomputer device that acts as a processing circuit. At least one memory circuit will also be part of the controller, including random access memory (RAM) and read only memory (ROM) devices. To store user entered information, if applicable to the particular tool model, a non-volatile storage device such as an EEPROM, NVRAM or flash memory device can be included.

[0044] The fastener feed mechanism 20 and corresponding fastener magazine 21 are disposed in the secondary housing section 96. The secondary housing section 96 is disposed below the handle 94 and the battery pack 12 and extends generally parallel to the handle 94 so as to communicate with the guide body 11. An electric motor 34 for driving the fastener drive reset mechanism 40 is disposed in the secondary housing section 96 so as to be located between the handle 94 and the fastener magazine 21. The electric motor 34 has an output that drives a gear set 35. The output of the gear set drives the fastener drive reset mechanism 40. The electric motor 34 can be, for example, an electrically powered brushless DC motor.

[0045] The fastener magazine 21 includes a magazine housing 22 and a fastener track (not shown) is disposed in the magazine housing 22. Individual fasteners, such as nails, are movable within the magazine 6. A feeder carriage (not shown) is disposed in the magazine housing 22 and is used to feed individual fasteners from the magazine 6 into the fastener drive mechanism 32. In the illustrated embodiment, the feeder carriage positions the fasteners within the guide body 11 in a position that is in line with the path of a drive member (e.g., blade 42) of the fastener drive mechanism 32 so that when the blade 42 moves through a drive stroke, its drive end will intercept the fastener and carry it to the fastener exit portion 10 at the bottom portion of the tool exit area.

[0046] The battery pack 12 is connected to a battery connection section 92, which is provided at a rear portion of a handle 94. The battery pack 12 provides electrical power to the controller, the electric motor 34, and other electrical devices within the power tool 1. The battery pack 12 is rechargeable. To this end, the battery pack 12 can be selectively removable from the handle 94 to allow charging within a dedicated charging device.

[0047] Referring to Figures 3-6 The tool housing 2 is a hollow rigid structure that encloses the fastener drive mechanism 32, the fastener drive return mechanism 40, the fastener feed mechanism 20, and the fastener cartridge 21. In addition, the tool housing 2 encloses other ancillary components of the power tool 1, including but not limited to the printed circuit board 14 and controller, the motor 34, the trigger switch 16, etc. The tool housing 2 is a composite of an outer layer 60 that provides the outer surface of the power tool housing and an inner layer 80 that is disposed on an inner surface of at least a portion of the outer layer.

[0048] The outer layer 60 of the composite structure provides a rigid outer shell and is thinner and more compliant relative to some conventional tool housings. The outer layer 60 is designed for controlled deformation without cracking. In some embodiments, the outer layer 60 is formed of a first material, which can be a thermoplastic polymer. In some embodiments, the thermoplastic polymer has a high tensile strength and is very resistant to physical impact and chemical corrosion. For example, suitable thermoplastic polymers include acrylonitrile butadiene styrene-polyamide (ABS-PA), acrylonitrile butadiene styrene-polyamide 12 (PA12), and acrylonitrile butadiene styrene-polyamide 6 (PA6). ABS-PA blends provide a balance of material toughness and stiffness. In some embodiments, the thickness of the outer layer 60 can have a maximum thickness in the range of 10 millimeters to 3 millimeters and a minimum thickness in the range of 5 millimeters to 1 millimeter. For example, in some embodiments, the thickness of the outer layer 60 can have a maximum thickness of 5 millimeters and a minimum thickness of 3 millimeters.

[0049] The outer layer of the tool housing 2 is an assembly of a concave first shell portion 61, a concave second shell portion 62, and a concave third shell portion 63. The first, second, and third shell portions 61, 62, 63 are formed separately and, when assembled, define an enclosed interior space 67.

[0050] The first housing portion 61 covers a first lateral side of the power tool 1, e.g., the left side of the power tool 1. The second housing portion 62 covers a second lateral side of the power tool 1, e.g., the right side of the power tool 1, so as to be opposite the first housing portion 61. When the first housing portion 61 and the second housing portion 62 are assembled, they are positioned such that their respective facing portions 61a, 62a of their peripheral edges abut, and the facing portions 61a, 62a are joined together. The joint or line of junction resulting from the assembly of the first and second housing portions 61, 62 is referred to as a first parting line 65. The first parting line 65 extends along a first circumferential portion of the tool housing 2, where the first circumferential portion lies in a first plane PI that divides the tool housing 2 into right and left sides. For example, the first plane PI can correspond to Figure 1 The tool housing 2 is shown in cross-section. In this configuration, the first housing portion 61 and the second housing portion 62 together provide most of the battery connection section 92, the handle 94, the sub-housing section 96, and the main housing section 90.

[0051] The third housing portion 63 is a generally cup-shaped structure that encloses the open top end of the main housing section 90, where the "top" of the tool housing 2 is identified using reference numeral 54. When the third housing portion 63 is assembled with the first and second housing sections 61, 62, a facing portion 63b of the outer peripheral edge of the third housing portion 63 abuts corresponding facing portions 61b, 62b of the outer peripheral edges of the first and second housing sections 61, 62, and the respective facing portions 63b, 61b, 62b are joined together. The joint or line of junction resulting from the assembly of the third housing portion 63 with the first and second housing portions 61, 62 is referred to as a second parting line 66. The second parting line 66 extends along a second circumferential portion of the tool housing 2, where the second circumferential portion lies in a second plane P2 that is perpendicular to the first plane PI. The third housing portion 63 provides a top cover corresponding to the rest of the main housing section 90.

[0052] In some embodiments, the third housing portion 63 can correspond to a removable cover that is selectively attached to, or detached from, the rest of the main housing section 90. Such a removable cover allows for servicing of internal wear parts within the fastener driving mechanism 32. The third housing portion 63 in the form of a removable cover can be secured to the rest of the main housing section 90 using fasteners (not shown), such as screws, or alternatively via other types of mechanical connections, such as press fits, snap fits, threaded engagements, etc.

[0053] The first, second, and third housing portions 61, 62, 63 are joined together along the first parting line 65 and the second parting line 66 so as to provide a single or unitary housing structure.

[0054] In some embodiments, the inward-facing surface 68 of the outer layer 60 is free of structurally reinforced protrusions, such as but not limited to ribs, at the location facing the inner layer 80.

[0055] Reference is also made to Figures 7-10 The inner layer 80 serves as a liner for the outer layer 60, such that the outward-facing surface 89 of the inner layer 80 faces the inward-facing surface 68 of the outer layer 60 without any intervening structure. In the illustrated embodiment, the inner layer 80 is not adhered to and / or bonded to the outer layer 60. However, in other embodiments, the inner layer 80 can be secured to the outer layer via adhesive, mechanical fasteners, or other known methods. For example, if it is deemed advantageous to the machining or performance of the power tool 1 to have the outer layer 60 and inner layer 80 bonded together, they can be bonded together.

[0056] The outward-facing surface 89 of the inner layer 80 is contoured to correspond to the contoured profile of the inward-facing surface 68 of the outer layer 60, whereby the gap between the inner layer 80 and the outer layer 60 is minimal or non-existent.

[0057] The inner layer 80 is disposed between the outer layer 60 and the internal components of the power tool 1. In some embodiments, the entire outer layer 60 is lined with the inner layer 80. In other embodiments, the inner layer 80 can be disposed only at critical locations of the tool housing 2. That is, the inner layer 80 can be disposed in predetermined locations where, for example, impact loads are likely to occur or where housing failure is more likely to occur.

[0058] When the power tool 1 is dropped, it can rotate in space until the heaviest portion faces downward. Thus, when dropped, the front 50 and top 54 of the tool housing 2 can experience more impact loads than other portions of the tool housing 2. To this end, in the illustrated embodiment, the inner layer 80 is disposed in the main housing segment 90 and is located beneath the outer layer 60 along the front 50 and top 54 of the power tool 1. In other words, the inner layer 80 is disposed between the outer layer 60 and the fastener driving mechanism 32. In other locations where ergonomic requirements result in complex shapes or where thermal loads need to be dissipated, the outer layer 60 can be thickened and the thickness of the inner layer 80 can be reduced or eliminated. In the illustrated embodiment, for example, the inner layer 80 is omitted from locations of the tool housing 2 that do not frequently experience impact loads, such as the battery connection segment 92, the handle 94, and the secondary housing segment 96. The outer layer 60 can have a first thickness in a first region of the tool housing 2 that corresponds to locations where the inner layer 80 is located beneath the outer layer 60, and a second thickness in a second region of the tool housing 2 that corresponds to locations where the inner layer is omitted, such as the handle 94. The first thickness is less than the second thickness due to the inner layer 80 reinforcing and strengthening the outer layer 60. This approach optimizes the housing regions so that maximum functionality is achieved while controlling weight and cost. This approach also minimizes the impact on the tool appearance and ergonomics.

[0059] The inner layer 80 is an assembly of an inner layer first portion 83 and an inner layer second portion 85. The inner layer first portion 83 has a U-shaped cross-section and is elongate along an axis extending between the top 54 and the bottom 56 of the power tool 1. The inner layer first portion 83 is located between the cylinder of the fastener driving mechanism 32 and a corresponding portion of the outer layer 60. In particular, the inner layer first portion 83 extends along the front of the power tool 1 and also extends along portions of the left and right lateral sides of the power tool 1. The inner layer second portion 85 is generally cup-shaped and serves as a liner for the third outer housing portion 63. When the inner layer first and second portions 83, 85 are assembled to provide the inner layer 80, facing portions 83a, 85a of the peripheral edges of the inner layer first and second portions 83, 85 abut one another along a third part line 87.

[0060] Further, the inner layer 80 extends across both the first part line 65 and the second part line 66, as the facing portions 83a, 85a of the peripheral edges of the inner layer 80 extend parallel to the second part line 66 and are offset (e.g., spaced apart) from the second part line 66. Additionally, portions 83b, 85b of the peripheral edges of the inner layer 80 that extend parallel to the first part line 65 are offset from the first part line 65.

[0061] The shape and size of the inner layer first and second portions 83, 85 are configured such that the third split line 87 lies in a third plane P3 that is parallel to the second plane P2 and offset from the second plane P2 such that the third split line 87 is closer to the top 54 of the power tool 1 than the second split line 66. As a result, the inner layer first portion 83 extends across the second split line 66 and the third split line 87 is inside the third housing portion 63.

[0062] The inner layer 80 of the composite structure supports the outer layer 60 and provides energy absorption during impact loading of the tool housing 2. In some embodiments, the inner layer 80 is a polymer foam. The polymer foam can be rigid or flexible as needed for the particular application. The inner layer 80 is more deformable and less dense than the outer layer 60. In particular, the density of the inner layer 80 is at most one third the density of the outer layer 60. In some implementations, the inner layer 80 can be a foam having a density that is one tenth, one thirtieth, or one fiftieth the density of the outer layer 60. The resulting tool housing 2 has excellent compression strength and energy absorption properties while being resistant to breakage. This construction is well suited for lightweighting and cost effective energy management in power tool housings.

[0063] For example, the inner layer 80 can be an expanded polyolefin (EPO). EPOs include expanded polyethylene (EPE), expanded polypropylene (EPP), expanded polybutylene (EPB), and copolymers of ethylene, propylene, and the like. The most preferred EPO is expanded polypropylene (EPP) and copolymers thereof with ethylene and butylene. The polymer is selected to provide the desired physical properties such as tensile strength, compression strength, modulus of elasticity, density, molding temperature, and the like. In some embodiments, the thickness of the inner layer 80 can be at least 1.5 times the thickness of the outer layer 60. In some embodiments, the thickness of the inner layer 80 can be 5 times, 10 times, or 40 times the thickness of the outer layer 60 depending on the amount of energy absorption needed for harsh terrain use or impact forces. In use, the deformability properties of the outer layer 60 allow the outer layer 60 to compress against the underlying inner layer 80 with only a small amount of deformation.

[0064] In some embodiments, the inner layer 80 and the outer layer 60 are molded in separate processes. By molding the outer layer 60 in a process that is separate from the molding of the inner layer 80, the inner layer 80 can be configured to extend across the split lines 65, 66. For example, when the tool housing 2 is viewed with the third housing portion 63 removed, the inner layer 80 extends across the split lines 65, 66 and the outer layer 60 does not extend across the split lines 65, 66. Figure 6), it can be seen that the first split line 65 of the outer layer 60 is offset from the parallel peripheral edge portions 83b, 85b of the inner layer 80. Additionally, the second split line 66 of the outer layer is offset from the third split line 87. If the front 50 of the power tool 1 is subjected to a severe impact near the first and / or second split lines 65, 66, the inner layer 80 will absorb the load. Furthermore, because the inner layer 80 extends across the split lines 65, 66 along the front of the power tool 1, the inner layer 80 will not separate near the split lines 65, 66. That is, even if the split lines 65, 66 separate due to the impact load, the underlying inner layer 80 will not separate at that location, providing a barrier between the mechanisms disposed in the tool housing 2 and the environment. With this construction, the mechanisms underlying the inner layer 80 are protected by the inner layer 80 because the inner layer 80 provides a cover and energy absorption. This approach is also more cost effective than some other processes because each molding process can be optimized for cycle time and material properties. By design, the inner surface geometry of the outer layer 60 nests in the underlying inner layer 80 because they are nearly identical.

[0065] In some embodiments, the outer layer 60 and the inner layer 80 can be molded as one unitary assembly. This approach can provide the greatest energy management opportunity, but can also increase cost and processing complexity. In some cases, processing parameters can compromise optimal material properties.

[0066] Molding the outer layer 60 separately from the inner layer 80 also provides benefits to manufacturers by allowing for improved impact resistance of existing power tools. This is accomplished by adding an internal layer of a second material to the inner surface of the power tool. This can be an economical way to upgrade existing power tools and can compensate for newer and much heavier batteries without the need to retool the housing. Although not all of the benefits with respect to impact load resistance can be realized by adding an internal layer, the incremental gains can provide the desired additional durability to the power tool.

[0067] The composite tool housing 2 provides the benefit of weight reduction because the wall thickness of the outer layer 60 is reduced relative to some conventional tool housings to produce a durable structure. Because all or most of the internal ribs of a conventional tool housing can be replaced by the inner layer 80 having a continuous or nearly continuous foam structure, the weight of the entire tool is immediately reduced. This construction is lightweight and provides a cost effective energy management in a power tool housing.

[0068] Although the power tool 1 is described as a gas-spring powered nailer, the nailer is not limited to having a gas spring drive mechanism. For example, in other embodiments, the nailer can have a gas combustion drive mechanism, a mechanical spring drive mechanism, or other drive mechanisms suitable for the desired application.

[0069] While the tool housing 2 is described above in relation to a hand-held gas nailer power tool, the tool housing 2 is not limited to use with a gas nailer. The tool housing 2 can be used with other types of nailers, such as a pneumatic nailer or a battery-powered nailer. Further, the tool housing 2 is not limited to use with a hand-held nailer and can be used with other hand-held power tools, including but not limited to a saw, a sander, a grinder, a paint sprayer, a mixer, a hammer, a jackhammer, etc.

[0070] Reference is made to Figure 11 and 12 The tool housing 2 is not limited to use with a hand-held power tool. For example, in some embodiments, the alternative embodiment tool housing 102 is used with a floor-standing power tool 101, such as a table saw, where a saw blade 110 and a motor (not shown) driving the saw blade are housed in the cabinet tool housing 102. The table saw 101 includes a planar work surface 104 that rests on a cabinet portion 105 of the tool housing 102, and the saw blade 110 can partially protrude through an opening in the work surface 104. The cabinet portion 105 can be supported relative to the ground by legs 106. The composite structure is provided in the cabinet 102 and includes an outer layer 160 and an inner layer 180, which provides a further benefit in that the expanded polyolefin aids in the attachment of metal and non-foam elements during the molding process. Other portions of the table saw 101, such as the work surface 104 and / or the legs 106, can not include the composite structure required for the particular application.

[0071] For a hand-held tool, it will be appreciated that the composite structure results in a more durable structure. For a larger, non-hand-held or cabinet-style power tool, such as a table saw, the composite structure results in an important structural element. In the case of the table saw 101, the main tool housing 102 acts as a large box feature that enhances the structural integrity of the tool 101 and increases the rigidity of the tool 101. As in the earlier embodiments, the composite structure also reduces the overall weight of the table saw 101.

[0072] The alternative illustrative embodiments of a power tool including a composite housing are described in detail above. It will be appreciated that only structures believed necessary to clarify the power tool and the composite housing are described herein. It is assumed that other conventional structures of power tools and structures of dependent and ancillary components are known and understood by those skilled in the art. Further, while working examples of a power tool including a composite housing have been described above, the power tool and / or the composite housing are not limited to the working examples described above, but rather can be variously designed without departing from the power tool and / or the composite housing set forth in the claims.

Claims

1. A power tool comprising a tool housing and a mechanism disposed within the tool housing, the tool housing comprising: an outer layer providing an outer surface of the power tool housing, the outer layer comprising a first material; and an inner layer disposed on an inner surface of a first region of the outer layer and omitted from an inner surface of a second region of the outer layer, the inner layer comprising a second material, wherein a density of the first material is at least three times a density of the second material, the outer layer is an assembly of a first concave housing portion and a second concave housing portion, the first housing portion is joined together with the second housing portion along a first parting line to provide an enclosed interior space housing the mechanism, the inner layer is disposed between the first region of the outer layer and the mechanism, and the inner layer has a first peripheral edge portion offset relative to the first parting line such that the inner layer continuously extends across the first parting line.

2. The power tool of claim 1, wherein the outer layer is an assembly of a first housing portion, a second housing portion, and a third concave housing portion, the third housing portion is joined together with the first housing portion and the second housing portion along a second parting line to provide an enclosed interior space housing the mechanism, and the inner layer has a second peripheral edge portion offset relative to the second parting line such that the inner layer continuously extends across the second parting line.

3. The power tool of claim 2, wherein, the inner layer is an assembly of a first inner layer portion and a second inner layer portion, the first inner layer portion abutting the second inner layer portion along a third parting line, and the third parting line is spaced apart from the second parting line.

4. The power tool of claim 1, wherein, the inner layer is located beneath the outer layer such that an outward facing surface of the inner layer faces an inward facing surface of the outer layer without any intervening structure, and the inner layer is not adhered to and bonded to the outer layer.

5. The power tool of claim 1, wherein, the inward facing surface of the outer layer is free of structural reinforcement protrusions at locations facing the inner layer.

6. The power tool of claim 1, wherein the outer layer has a non-uniform thickness such that the outer layer has a first thickness in a first region of the tool housing and a second thickness in a second region of the tool housing, the first thickness is less than the second thickness, and the inner layer is disposed on an inner surface of the outer layer within the first region of the tool housing.

7. The power tool of claim 6, wherein the power tool is a hand-held fastener driving tool comprising: the mechanism disposed at a first end of the tool housing, the mechanism comprising a fastener driving mechanism; a power source disposed at a second end of the tool housing; and a handle extending between the first end and the second end, and the first region of the tool housing comprises the first end, and the second region of the tool housing comprises the handle.

8. The power tool of claim 6, wherein the power tool housing comprises: a cabinet portion housing the mechanism; a planar work surface supported on the cabinet portion; and a support member configured to support the cabinet portion relative to an external support surface, and the first region of the tool housing comprises the first end, and the second region of the tool housing comprises the handle. A first region of the tool housing corresponds to the cabinet portion, and a second region of the tool housing corresponds to the support member.

9. The power tool of claim 1, wherein the first material is a thermoplastic polymer, and the second material is a polymer foam.

10. The power tool of claim 1, wherein a thickness of the inner layer is at least 1.5 times a thickness of the outer layer.

11. A power tool comprising a tool housing and a mechanism disposed within the tool housing, the tool housing comprising: an outer layer providing an outer surface of the power tool housing; and an inner layer disposed on an inner surface of a first region of the outer layer and omitted from an inner surface of a second region of the outer layer, wherein the outer layer is an assembly of a first concave housing portion and a second concave housing portion joined together along a first part line to provide an enclosed interior space housing the mechanism, the inner layer is disposed between the first region of the outer layer and the mechanism, and the inner layer has a first peripheral edge portion offset from the first part line such that the inner layer continuously extends across the first part line.

12. The power tool of claim 11, wherein the outer layer comprises a first material, the inner layer comprises a second material, and a density of the first material is at least three times a density of the second material.

13. The power tool of claim 11, wherein, the outer layer is an assembly of the first housing portion, the second housing, and a third concave housing portion, the third housing portion is joined together with the first housing portion and the second housing portion along a second part line to provide the enclosed interior space, and a second peripheral edge portion of the inner layer is offset from the second part line such that the inner layer continuously extends across the second part line.

14. The power tool of claim 13, wherein, the inner layer is an assembly of a first inner layer portion and a second inner layer portion, the first inner layer portion abutting the second inner layer portion along a third part line, and the third part line is spaced apart from the second part line.

15. The power tool of claim 11, wherein, the inner layer is located beneath the outer layer such that an outward-facing surface of the inner layer faces an inward-facing surface of the outer layer without any intervening structure, and the inner layer is not adhered to and bonded to the outer layer.

16. The power tool of claim 11, wherein the outer layer has a non-uniform thickness such that the outer layer has a first thickness in a first region of the tool housing and a second thickness in a second region of the tool housing, the first thickness is less than the second thickness, and the inner layer is disposed on an inner surface of the outer layer within the first region of the tool housing.

17. The power tool of claim 16, wherein the power tool is a hand-held fastener-driving tool comprising: the mechanism disposed at a first end of the tool housing, the mechanism comprising a fastener-driving mechanism; a power source disposed at a second end of the tool housing; and a handle extending between the first end and the second end, the first region of the tool housing comprises the first end, and the second region of the tool housing comprises the second end. The second region of the tool housing comprises a handle. The second region of the tool housing comprises a handle.

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