Surgical impactor

Abstract

In summary, the invention herein is an electrically driven impactor adapted for use in surgical procedures, comprising: a housing; a brushless DC motor including a stator having multiple coils and a rotor having multiple magnets; a motor controller with a motor driver that supplies current to the coils of the stator to rotate the rotor around the stator; a planetary gear train with an input, a sun gear, planetary gears, a ring gear, and an output; a shaft including a shaft section having a non-circular cross-sectional shape; and an impact assembly including a drive component and a driven component: (i) the drive component has a defined passage inside and provides clearance for the non-circular rotating component and the rolling subassembly: (1) the non-circular rotating component is mounted to the rolling subassembly; (2) the non-circular rotating component and the rolling subassembly are rotated by the output of the gear train; (3) rolling The subassembly comprises a plurality of shafts, rollers, and forks, each roller being pressed against each shaft, and each shaft being press-fitted into each fork; (ii) The driven component comprises a collision portion and a stepped portion having a non-circular bore defined inside: (1) The shaft section having a non-circular cross-sectional shape extends through the non-circular bore; (2) The stepped portion further comprises a first roller bearing surface, a second roller bearing surface, a top surface, a first inclined portion, and a second inclined portion, each of these (3) The first inclined portion extends radially from the non-circular bore; the second inclined portion extends axially from the first roller bearing surface to the top surface; (4) the top surface is located between the first roller bearing surface and the second roller bearing surface; (iii) the roller of the rolling subassembly rotates on the first roller bearing surface, raising the first inclined portion to the top surface, and then descending the second inclined portion to the second roller bearing surface.

Description

Technical Field

[0001] This patent application relates to an electric surgical impacter used in joint replacement surgery.

Background Art

[0002] Patients with osteoarthritis or joint injuries often undergo arthroplasty to relieve pain and restore normal joint function. As part of the surgery, the problematic joint is surgically removed, the patient's joint is prepared for the prosthesis, and then the artificial components of the prosthesis are fixed within the patient's living tissue. To prepare the patient's joint to receive the artificial component, the surgeon must use a mallet to drive special instruments such as broaches or bone compressors into the patient's living tissue. Further, to achieve press-fitting between the patient's living tissue and the artificial joint component, the surgeon typically must drive in the artificial joint component.

Summary of the Invention

Problems to be Solved by the Invention

[0003] As described above, surgical impaction typically requires the use of a mallet. However, the use of a mallet has drawbacks. Since surgical impaction is a necessary aspect of joint replacement surgery, surgeons have reported that repeated use of a mallet over a long period causes fatigue and injury to the surgeon. Many surgeons have to undergo surgery themselves or shorten their careers. Therefore, there is a strong need for an electric instrument that replaces the use of a mallet and thereby reduces surgeon fatigue and injury.

[0004] Furthermore, precisely controlling the speed of the mallet during impact is extremely difficult, and therefore, controlling how deeply the mallet penetrates the instrument and prosthesis component into the patient's tissue is also extremely difficult. Patients with osteoarthritis often have reduced bone quality and cannot withstand excessive force from the mallet impact; however, if the mallet moves too quickly, it will deliver an excessively strong impact to the patient's tissue, thereby causing a fracture. The prosthesis component must be implanted precisely, but if the mallet impact is too strong, the prosthesis component will be pushed in too deeply, while if the impact is too light, it will result in insufficient fixation of the prosthesis component. Therefore, there is a need for an electrically powered instrument with a limited stroke that delivers sufficient force to penetrate the patient's tissue and fix the implant.

[0005] The foregoing does not encompass all the drawbacks associated with prior art brooches; however, the present invention aims to overcome these (and other) drawbacks inherent in prior art systems. The advantages of the present invention will be readily apparent to those skilled in the art after reading the disclosure provided herein. [Means for solving the problem]

[0006] The present invention is defined by the claims set forth herein; however, in short, the present invention is an electrically driven impactor adapted for use in surgical procedures, comprising: a housing; a brushless DC motor including a stator having multiple coils and a rotor having multiple magnets; a motor controller with a motor driver that supplies current to the coils of the stator to rotate the rotor around the stator; a planetary gear train having an input, a sun gear, planetary gears, a ring gear, and an output; a shaft including a shaft section having a non-circular cross-sectional shape; and an impact assembly including a drive component and a driven component: (i) the drive component has a defined passage inside that provides clearance for the non-circular rotating component and the rolling subassembly; (1) the non-circular rotating component is mounted to the rolling subassembly; (2) the non-circular rotating component and the rolling subassembly are connected to the gear train (ii) The driven component comprises a collision portion and a stepped portion having a noncircular bore defined inside: (1) The shaft section having a noncircular cross-sectional shape extends through the noncircular bore; (2) The stepped portion further comprises a first roller bearing surface, a second roller bearing surface, a top surface, a first inclined portion, and a second inclined portion (3) The first inclined portion extends axially from the first roller bearing surface to the top surface, and the second inclined portion extends axially from the second roller bearing surface to the top surface; (4) The top surface is located between the first roller bearing surface and the second roller bearing surface; (iii) The roller of the rolling subassembly rotates on the first roller bearing surface, raising the first inclined portion to the top surface, and then descending the second inclined portion to the second roller bearing surface. [Brief explanation of the drawing]

[0007] [Figure 1] Perspective view of a surgical impactor [Figure 2] Oblique view of a surgical impactor from one side. [Figure 3] Perspective view of the motor, gear train, output, and impact mechanism of a surgical impactor. [Figure 4] Cross-sectional view of the motor, gear train, output, and impact mechanism of a surgical impactor. [Figure 5] Perspective view of the motor, gear train without ring gear, output, and impact mechanism of a surgical impactor. [Figure 6] Perspective view of the gear train of a surgical impactor. [Figure 7] Perspective view of the motor rotor [Figure 8] Perspective view of the motor stator [Figure 9] Perspective view of the ring gear in the gear train. [Figure 10] Perspective view of the ring gear in the gear train. [Figure 11] Cross-sectional view of an impactor without a ring gear [Figure 12] Perspective view of the solar gear in the gear train [Figure 13] Side view of the sun gear in the gear train. [Figure 14] Front view of the sun gear in the gear train. [Figure 15] Side view of the sun gear in the gear train. [Figure 16] Cross-sectional view of the solar gear along line AA shown in Figure 15. [Figure 17] Side view of the planetary gears in the gear train. [Figure 18] Front view of the planetary gears in the gear train. [Figure 19] Rear view of the planetary gears in the gear train. [Figure 20] Front view of a surgical impactor without housing and ring gear. [Figure 21] Cross-sectional view of the surgical impactor along line AA shown in Figure 20. [Figure 22] Side view of the gear train input plate [Figure 23] Diagram of the rotor side of the input plate [Figure 24] Perspective view of the input plate [Figure 25] Diagram of the gear side of the input plate [Figure 26] Diagram of the carrier structure of the sun gear [Figure 27] Cross-sectional view of the sun gear in FIG. 26 [Figure 28] Perspective view of a surgical impactor without a housing or ring gear [Figure 29] Perspective view of the output of the gear train [Figure 30] Front view of the output of the gear train [Figure 31] Side view of the output of the gear train [Figure 32] Cross-sectional view along line A-A of the output in FIG. 31 [Figure 33] Side view of the output, tubular member, drive component, driven component, and shaft section [Figure 34] Cross-sectional view along line A-A of FIG. 33 [Figure 35] Perspective view of the tubular member [Figure 36] Front view of the tubular member [Figure 37] Detailed view of region "A" of the tubular member shown in FIG. 36 [Figure 38] Perspective view of the drive component [[ID=...]] [Figure 39] Perspective view of the drive component [Figure 40] Perspective view of the drive component [Figure 41] Perspective view of the drive component and the driven component [Figure 42] Perspective view of the non-circular rotating component [Figure 43] Diagram of the first end face of the non-circular rotating component [Figure 44] Perspective view of the non-circular rotating component [Figure 45] Front view of a surgical impactor without a housing [Figure 46] Perspective view of the rolling sub-assembly [Figure 47] Bottom view of the rolling sub-assembly [Figure 48] Perspective view of the rolling sub-assembly [Figure 49] Side view of the rolling sub-assembly [Figure 50] Side view of the stepped portion of the driven component [Figure 51] Side view of the stepped portion of the driven component [Figure 52] Top view of the stepped portion of the driven component. [Figure 53] Cross-sectional view along line AA of the stepped portion of the driven component shown in Figure 50. [Figure 54] Cross-sectional view of the stepped portion of the driven component along the BB line shown in Figure 51. [Figure 55] Side view of the drive component, shaft section, and driven component. [Figure 56] Figure 55 shows a cross-sectional view of the drive component, shaft section, and driven component along line AA. [Figure 57a] Side view of the shaft section and driven components [Figure 57b] Cross-sectional view of the shaft section and driven component along line AA shown in Figure 57a [Figure 58] Perspective view of the shaft section [Figure 59] Side view of the shaft section [Figure 60] Perspective view of the shaft section [Figure 61] Perspective view of an impactor without a battery [Figure 62] Cross-sectional view of the housing with the ring gear pressed in. [Figure 63] Cross-sectional view of the impactor [Figure 64] Perspective view of an impactor with a battery inserted inside. [Figure 65] Perspective view of the impactor into which the battery is about to be inserted. [Figure 66] Perspective view of motor mounting components including battery receptacle [Figure 67] Top view of the motor mounting component [Figure 68]Top view of the battery receptacle included with the motor mounting component. [Figure 69] Perspective view of motor mounting components including battery receptacle [Figure 70] Side view of motor mounting components including battery receptacle [Figure 71] Cross-sectional view along line AA in Figure 70 [Figure 72] Side view of motor mounting components including battery receptacle [Figure 73] Cross-sectional view along line AA in Figure 72 [Figure 74] Perspective view of the cap sealing the second housing opening. [Figure 75] Side view of the cap sealing the second housing opening. [Figure 76] Cross-sectional view along line AA in Figure 75 [Figure 77] Perspective view of the cap sealing the first housing opening. [Figure 78] Side view of the cap sealing the first housing opening. [Figure 79] Cross-sectional view along line AA in Figure 78 [Figure 80] Top view of the handle [Figure 81] Cross-sectional view of the handle along line AA [Figure 82] Partially disassembled side view of the handle [Figure 83] Partially disassembled side view of the handle [Figure 84] Partially disassembled side view of the handle [Figure 85] Partially disassembled side view of the handle [Figure 86] Partially disassembled top view of the handle [Figure 87] Top view of the handle body [Figure 88] Top view of the second opening of the impactor [Modes for carrying out the invention]

[0008] Figures 1 and 2 show perspective views of an impactor 1000 constituting a preferred embodiment of the present invention. The impactor 1000 is powered by a plurality of lithium-ion battery cells arranged in series to preferably supply 18 to 24 volts. As shown in Figures 1 and 2, the impactor 1000 comprises a housing 1100 and a handle 1200. The components within the housing 1100 and the handle 1200 are manufactured from a polyether ketone polymer known as "PEEK".

[0009] Figures 3 and 4 provide additional illustrations of the impactor 1000. Figure 4 provides the external shape of the housing 1100 and handle 1200 shown in Figure 2. In Figures 3 and 5, the housing 1100 and handle 1200 shown in Figure 1 have been completely removed, thereby providing perspective views of the motor 1300 (preferably a brushless DC motor including a stator 1310 and rotor 1320), gear train 2000, output 1500, and impact assembly 3000. As will be described more fully herein, the gear train 2000 is a planetary gear train in which each gear is manufactured from PEEK, further comprising a sun gear 2100 having multiple teeth 2111, a planetary gear 2200 having multiple teeth 2211, and a ring gear 2300 having multiple teeth 2311.

[0010] Referring to Figures 20 and 21, these provide a perspective view and a cross-sectional view along line AA, respectively, where the gear train 2000 is shown without the ring gear 2300. The gear train 2000 provides the impactor 1000 with a reduction ratio that increases torque. In the planetary gear train 2000 of a preferred embodiment, the ring gear 2300 is fixed and held, while the sun gears 2100-a and 2100-b rotate around the impactor shaft 2500 and, like the ring gear 2300, remain fixed in place and do not rotate.

[0011] The impactor shaft 2500 is a rod of titanium (or alternatively stainless steel) and is ground to produce an outer cylindrical shaft surface 2510, which has a diameter that is precise and suitable for the rotation of the sun gears 2100-a and 2100-b. The outer cylindrical shaft surface 2510 radially surrounds the shaft axis 2501 and extends axially between a pair of opposing shaft ends 2502 and 2503 (referred to as the "first" shaft end 2502 and the "second" shaft end 2503 to distinguish one end from the other).

[0012] A shaft flange 2511 located at the first shaft end 2502 extends radially from the outer cylindrical shaft surface 2510 to align the stator 1310 of the brushless DC motor 1300. In a preferred embodiment, both the shaft flange 2511 and the stator 1310 are bolted to a motor mounting component 2520 (made from PEEK). Advantageously, the outer cylindrical shaft surface 2510 includes an axial stopper or cylindrical bushing that provides axial clearance between the stator 1310 and the rotor 1320; the axial clearance is dimensioned so that the magnets in the rotor 1320 are axially aligned with the coils in the stator 1310.

[0013] As described above, the rotor 1320 comprises a rotor shaft 1321 and several permanent magnets 1322, 1323, 1324, 1325, 1326, 1327, 1328, and 1329 (as shown in Figure 7); similarly, the stator 1310 comprises a stator shaft 1311 and several coils 1312, 1313, 1314, 1315, 1316, and 1317 (as shown in Figure 8). The coils 1312-1317 are formed by winding copper wire around several electromagnetic steel punches, which together are stacked to form a single component. The electromagnetic steel punches are equally spaced radially apart, and the coils 1312-1317 are also equally spaced radially apart around the stator shaft 1311.

[0014] The permanent magnets 1322-1329 within the rotor 1320 are arranged radially around the rotor shaft 1321, with alternating polarity. As shown in Figure 7, the magnet designated "1322" is adjacent to the magnet designated "1323," which is adjacent to the magnet designated "1324." Thus, each of the magnets 1322-1329 has a polarity opposite to that of the adjacent magnet on either side.

[0015] As described above, the shaft flange 2511 aligns the stator 1310 and thus ensures that the shaft axis 2501 and the stator axis 1311 are aligned when bolted to the motor mounting component 2520. An axial stopper or cylindrical bushing provided on the outer cylindrical shaft surface 2510 positions the permanent magnets 1322-1329 in the stator 1320, which are radially arranged around the coils 1312-1317 in the stator 1310. As described above, in a preferred embodiment, the rotor 1320 is an external rotor that extends radially around the coils 1312-1317 of the stator 1310.

[0016] In addition to the coils 1312-1317 described above, the stator 1310 is provided with Hall effect sensors; as shown in Figure 8, the stator 1310 is provided with multiple Hall effect sensors (designated 1318-a, 1318-b, and 1318-c). The Hall effect sensors 1318-a, 1318-b, and 1318-c provide the position of the magnets 1322-1329 in the rotor 1320 relative to the coils 1312-1317 in the stator 1310. When each of the magnets 1322-1329 passes through the respective Hall effect sensors 1318-a, 1318-b, and 1318-c, a signal is provided to the motor controller 1350.

[0017] Based on signals from at least one of the Hall effect sensors 1318-a, 1318-b, and 1318-c, the motor controller 1350 causes current to flow through at least one of the coils 1312-1317, thereby inducing a magnetic field within the stator 1310. The induced magnetic field either attracts or repels at least one of the permanent magnets 1322-1329 in the rotor; thus, the induced magnetic field causes the rotor 1320 to rotate around the stator 1310.

[0018] In a preferred embodiment, the motor controller 1350 is a motor driver; however, in an alternative embodiment, the motor controller 1350 is a microcontroller or microprocessor, and in yet another alternative embodiment, the motor controller 1350 is a microcontroller or microprocessor that is communicatively linked to the motor driver.

[0019] Since the rotor 1320 is connected to at least one solar gear 2100, when the induced magnetic field in the stator 1310 rotates the rotor 1320, the teeth 2111 of at least one solar gear 2100 also rotate. The rotating teeth 2111 of the solar gear 2100 mesh with the teeth 2211 of at least one planetary gear 2200, which meshes with the teeth 2311 of the ring gear 2300. Since the ring gear 2300 is fixed and held in place, the planetary gear 2200 rotates around the outer diameter 2102 of the solar gear 2100 and the inner diameter 2302 of the ring gear 2300. Thus, the aforementioned combination of solar gear and planetary gear can be considered a "set".

[0020] Figures 9 and 10 show perspective views of the ring gear 2300 included in the gear train 2000. As described above, the ring gear 2300 comprises a ring gear shaft 2301, a cylindrical outer ring surface 2303, and a number of teeth 2311 (referred to as “internal teeth” or “ring teeth”). The ring teeth 2311 are arranged around the inner diameter 2302 of the ring gear 2300 and extend radially inward toward the ring gear shaft 2301. The ring teeth 2311 are configured to cooperate with the planetary gear 2200 and the sun gear 2100, as shown in Figures 6 and 11. Each tooth of the ring gear 2300 has a ring gear pitch point that mates with the corresponding pitch point on each tooth of the planetary gear 2200 (which mates with the corresponding pitch point on each tooth of the sun gear 2100).

[0021] In a preferred embodiment, the gear blank for the ring gear 2300 is manufactured by injecting PEEK into a mold; after injection molding, the blank is turned to an inner diameter suitable for the desired tooth contour, and then the multiple teeth 2311 are cut on a gear shaper. For manufacturing efficiency, the ring gear 2300 is supplied in an extended length so that a single ring gear 2300 can mate with multiple sets of sun gear and planetary gear combinations; however, in an alternative embodiment, multiple ring gears are used, one for each set of sun gear and planetary gear combinations.

[0022] Referring here to Figures 12, 13, and 14, the perspective view of the sun gear 2100 shows that the sun gear is a single unit comprising an axis 2101 and a pair of ends 2103, 2104 (referred to as the “first sun gear end” and designated as “2103” and the “second sun gear end” and designated as “2104”). The sun gear 2100 further comprises a gear structure 2110 and a carrier structure 2120. The gear structure 2110 extends axially from the first sun gear end 2103 and includes a plurality of teeth 2111 (referred to as “sun teeth” to distinguish the teeth of the sun gear from the teeth of other gears referred to herein). As shown in Figure 14, the sun teeth 2111 extend radially from the gear structure 2110 and include a pitch point (referred to as the “sun gear” pitch point).

[0023] The carrier structure 2120 is configured to carry motor-gear components such as the planetary gear 2200 or input plate (shown in Figures 22, 23, 24, and 25, and designated “2400”). As shown in Figures 14 and 16, the carrier structure 2120 extends axially and radially from the gear structure 2110 to form a flange 2121 (referred to as the “gear” flange to distinguish it from other flanges disclosed herein). As shown in Figure 16 (a cross-sectional view of the sun gear 2100) and Figure 14 (a perspective view of the sun gear 2100), at least one opening (and preferably more openings) is formed within the carrier structure 2120. Each opening 2122, 2123, 2124, and 2125 is provided with an axis (indicated as “2126”, “2127”, “2128”, and “2129”, respectively in Figure 12). Furthermore, each of the openings 2122-2125 is dimensioned to at least partially accommodate a planetary gear, such as the planetary gear 2200 shown in Figures 17, 18, and 19.

[0024] As shown in Figure 17, the planetary gear 2200 comprises a shaft 2201 (referred to as the “planetary” shaft to distinguish it from other shafts disclosed herein), a pair of ends (referred to as the “first planetary gear end 2203” and the “second planetary gear end 2204”), and a shaft 2202 (referred to as the “planetary gear shaft” to distinguish it from other shafts disclosed herein). The planetary gear shaft 2202 comprises an outer cylindrical surface 2209, which is press-fitted axially through the inner diameter of a bearing, preferably a deep groove ball bearing, and is dimensioned to form a planetary gear bearing assembly. The outer cylindrical surface 2209 of the planetary gear 2200 extends axially from the first planetary gear end 2203 and terminates at a stopper 2207 for the bearing.

[0025] The planetary gear 2200, which extends radially and axially from the stopper 2207, is provided with a number of external teeth 2211, as shown above and in Figures 18 and 19 (the planetary teeth 2211 are referred to as “planetary” teeth to distinguish them from the teeth of other gears disclosed herein). The planetary teeth 2211 have pitch points (referred to as “planetary gear pitch points”) and are shaped to contact the pitch points of the sun teeth 2111.

[0026] The planetary gear shaft 2202 is dimensioned to fit into each of the openings 2122, 2123, 2124, and 2125 formed within the carrier structure 2120 of the sun gear 2100. Each of the openings 2122-2125 is located radially from the sun gear shaft 2101, and as shown in Figure 6, the planetary gear pitch points are in contact with both the sun gear pitch points and the ring gear pitch points. In a preferred embodiment, each of the openings 2122-2125 has an inner diameter (referred to as “bearing IDs” in Figures 12 and 14, and designated as “2132”, “2133”, “2134”, and “2135”). Each bearing ID of the openings 2122-2125 is cylindrical and dimensioned so that the outer diameter of the deep groove ball bearing described above can be press-fitted therein.

[0027] Figure 21 shows a number of deep groove ball bearings (referred to as 2141, 2142, 2143, and 2144), at least one of which is press-fitted into one of the bearing IDs defined within each opening. Figure 21 also shows each bearing 2141-2144 pressed into each of the planetary gear shafts 2202-a, 2202-b, 2202-c, and 2202-d. A retaining plate 2145 is fixed to the carrier structure via through holes 2146, 2147, 2148, and 2149 defined inside, to hold each of the bearings 2141-2144 within each bearing ID 2132-2135.

[0028] Referring now to Figure 16, the solar gear 2100 comprises a solar gear cavity 2160. As shown in Figure 16, the solar gear cavity 2160 comprises a wall defined within the solar gear 2100 and cylindrical around the solar gear shaft 2101. The wall (hereinafter referred to as the "first cylindrical wall," and designated as "2161" in Figure 16) is dimensioned to receive the impactor shaft 2500. In a preferred embodiment, the cavity 2160 comprises a plurality of cylindrical walls (indicated as "2162" and "2163" in Figure 16, and referred to as the "second" and "third" cylindrical walls, respectively, to distinguish one wall from another).

[0029] To allow the sun gears 2100-a and 2100-b to rotate around the shaft 2500 while the shaft 2500 remains stationary, the second cylindrical wall 2162 and the third cylindrical wall 2163 are dimensioned so that the bearings can be inserted into the cavity 2160. In a preferred embodiment, the deep groove ball bearings are pressed onto the impactor shaft 2500, and then each of the sun gears is pressed onto the deep groove ball bearings; thus, the bearings 2171 and 2172 are shown pressed onto the impactor shaft 2500, and then the sun gear designated "2100-a" is subsequently pressed onto the bearings 2171 and 2172. Similarly, the bearings 2173 and 2174 are shown after being pressed onto the impactor shaft 2500, and then the sun gear designated "2100-b" is subsequently pressed onto the bearings 2173 and 2174. Therefore, the sun gears 2100-a and 2100-b are pressed against the impactor shaft 2500 such that the axis 2501 of the impactor shaft and the respective axes 2101 of the sun gears 2100-a and 2100-b are coaxial (or at least substantially coaxial).

[0030] As described above, the carrier structure 2120 is molded to support the motor-gear component; and as also described above, the motor-gear component may take multiple forms, including the planetary gear 2200 shown in Figures 17, 18, and 19, and the input plate 2400 shown in Figures 22, 23, 24, and 25. The input plate 2400 is provided with multiple through holes for fastening the rotor 1320 and one of the sun gears 2100-a, 2100-b. As the aforementioned fastening connections suggest, the input plate 2400 is positioned adjacent to the stator 1310 and is therefore made of aluminum to provide a heat sink for the coils 1312-1317 in the stator 1310; however, in alternative embodiments, the input plate 2400 may be made of PEEK, titanium, or stainless steel.

[0031] Furthermore, the input plate 2400 comprises an input shaft 2401 (shown in Figures 22 and 24), a rotor side 2410 (shown in Figures 22 and 23), and a gear side 2420 (shown in Figures 22, 24, and 25). The rotor side 2410 of the input plate 2400 is provided with a first register 2411, which is molded and dimensioned so that the rotor 1320 is centered and axially aligned when fixed to the input plate 2400. In a preferred embodiment, the first register 2411 includes a raised surface 2412 that extends axially from the rotor side 2410 of the input plate 2400 and provides a rotor surface 2413. The rotor surface 2413 is molded to match the alignment surface on the rotor 1320, and therefore, in a preferred embodiment, the rotor surface 2413 is molded cylindrically around the shaft 2401 of the input plate 2400.

[0032] As described above, the gear side 2420 of the input plate 2400 includes a second register 2422, which is molded and dimensioned to axially align when the gear (e.g., one of the sun gears 2100-a, 2100-b) and the rotor 1320 are fixed together; therefore, the second register 2422 includes position mating surfaces. As shown in Figures 24 and 25, the second register 2422 includes a plurality of position mating surfaces 2423, 2424 (referred to as the "first" position mating surface 2423 and the "second" position mating surface 2424 for distinction from one another). The position mating surfaces 2423, 2424 are preferably frustoconical; however, in alternative embodiments, the position mating surfaces 2423, 2424 are curved or spherical. In yet another alternative embodiment, the position mating surfaces 2423, 2424 are cylindrical.

[0033] The positional mating surfaces 2423 and 2424 extend axially from the gear side 2420 of the input plate 2400 and terminate at the annular positional mating surface 2422. The frustoconical first positional mating surface 2423 extends radially inward toward the input plate axis 2401, and the second positional mating surface 2424 extends radially outward away from the input plate axis 2401; thus, the first and second positional mating surfaces 2423 and 2424 provide a positional structure 2425 with respect to the input plate 2400 that tapers as it extends axially from the gear side 2420 of the input plate 2400.

[0034] It is advantageous that the gear side 2420 of the input plate 2400 and the carrier structure 2120 of the sun gear 2100 complement each other. Therefore, a circular groove 2130 is defined within the carrier structure 2120 of the sun gear 2100. The circular groove 2130 surrounds the sun gear shaft 2101 and includes a plurality of frustoconical surfaces (referred to as the "first" and "second" frustoconical gear surfaces, designated as "2133" and "2134" in Figures 26 and 27, respectively). In a preferred embodiment, the first and second frustoconical gear surfaces 2133, 2134 terminate at an annular gear surface 2132.

[0035] The first and second frustoconical gear surfaces 2133 and 2134 have the cross-sectional shapes shown in Figure 27. As shown in the figure, the first frustoconical gear surface 2133 extends axially toward the gear structure 2110 of the sun gear 2100 and radially inward toward the sun gear axis 2101. Similar to the first frustoconical gear surface 2133, the second frustoconical gear surface 2134 also extends axially toward the gear structure 2110, but unlike the first frustoconical gear surface 2133, the second frustoconical gear surface 2134 extends radially outward from the sun gear axis 2101. Therefore, the frustoconical gear surfaces 2133 and 2134 provide a taper to the circular groove 2130 within the carrier structure 2120 as the frustoconical gear surfaces 2133 and 2134 extend axially from the carrier structure 2120 toward the gear structure 2110 of the sun gear 2100.

[0036] Comparing Figures 22 and 25 with Figures 26 and 27, the alignment structure 2425 of the input plate 2400 (shown in Figures 22 and 25) and the circular groove 2130 of the carrier structure 2120 of the sun gear 2100 (shown in Figures 26 and 27) have complementary shapes. Therefore, the alignment structure 2425 of the input plate 2400 fits into the circular groove 2130 of the sun gear 2100, ensuring that the input plate 2400 and the sun gear 2100 are axially aligned when they are fixed together. As described above, the first positional fitting surface 2423 of the input plate alignment structure 2425 extends axially from the gear side 2420 of the input plate 2400 and radially inward toward the input plate axis 2401, similar to how the first frustoconical gear surface 2133 extends axially toward the gear structure 2110 away from the carrier structure 2120 and radially inward toward the sun gear axis 2201.

[0037] Similarly, the second positional fitting surface 2424 of the input plate alignment structure 2425 extends axially from the gear side 2420 of the input plate 2400 and radially outward from the input plate axis 2401, just as the second frustoconical gear surface 2134 extends axially from the carrier structure 2120 toward the gear structure 2110 and radially outward from the sun gear axis 2201; therefore, the alignment structure 2425 of the input plate 2400 is provided with a taper. As a result, when the input plate 2400 is fixed to the sun gear 2100, as shown in Figure 21, the taper of the alignment structure 2425 pulls the alignment structure 2425 of the input plate 2400 into the circular groove 2130 defined within the carrier structure 2120 of the sun gear 2100, causing the input plate 2400 and the sun gear 2100 to be more closely aligned axially.

[0038] As described above with respect to Figures 3, 4, 5 and 28, the impactor 1000 is provided with an output 1500. The output 1500 is manufactured from PEEK and comprises an output shaft 1501 and an output structure 1510, as shown in Figure 29. Extending both axially and radially from the output structure 1510 is an output flange 1521, which functions similarly to how the carrier structure 2120 functions on the sun gear 2100.

[0039] Similar to the carrier structure 2120 of the solar gear, the output flange 1521 of the output 1500 is configured to carry motor-gear components 2100 such as the planetary gear 2200 shown in Figures 17, 18, and 19, or the input plate 2400 shown in Figures 22, 23, 24, and 25. Within the output flange 1521, at least one opening (and preferably more openings) is formed, as shown in Figures 29 and 30 (perspective view of the output 1500) and Figure 32 (sectional view of the output 1500). As shown in Figures 29, 30, and 32, a preferred embodiment comprises a plurality of openings 1522, 1523, 1524, 1525, and 1561, each of which has an axis (the axes corresponding to openings 1522, 1523, 1524, and 1525 are called “opening” axes and are designated “1526,” “1527,” “1528,” and “1529,” respectively in Figure 30).

[0040] Each of the openings 1522, 1523, 1524, and 1525 is dimensioned to at least partially receive the planetary gear, more specifically, the planetary gear shaft 2202 of the planetary gear 2210 shown in Figures 17, 18, and 19. Thus, each of the openings 1522–1525 is radially located from the output shaft 1501 (shown as "X" inside the circle in Figure 6), as shown in Figure 6, with the planetary gear pitch point in contact with both the sun gear pitch point and the ring gear pitch point.

[0041] Just as each of the planetary apertures 2122-2125 of the solar gear 2100 is provided with an inner diameter, each of the apertures 1522, 1523, 1524, and 1525 of the output 1500 is also provided with an inner diameter (these are called "bearing IDs" and are designated as "1532," "1533," "1534," and "1535" in Figure 32). Each bearing ID is cylindrical and dimensioned so that a bearing can be press-fitted into it. As shown in Figure 21, the output 1500 is equipped with several deep groove ball bearings (indicated as "2143" and "2144" in Figure 21).

[0042] As shown in Figure 32, the output 1500 comprises an output cavity 1560 molded to receive the impactor shaft 2500. The output cavity 1560 includes a plurality of cylindrical surfaces (referred to as the “first,” “second,” and “third” cylindrical surfaces to distinguish one from the other, and designated as “1561,” “1562,” and “1563,” respectively). The first and second cylindrical surfaces 1561, 1562 are dimensioned so that bearings can be press-fitted into the cavity 1560; in a preferred embodiment, deep groove ball bearings 1575, 1579 are pressed onto the impactor shaft 2500 and press-fitted into the cylindrical cavity 1560 created by the cylindrical surfaces 1561, 1562.

[0043] As described above, it is within the scope of the present invention for the output flange 1521 to hold an input plate such as the input plate 2400 shown in Figures 22, 23, 24 and 25. Therefore, in the alternative embodiment, the output flange 1521 is molded to complement the register 2422 on the gear side 2420 of the input plate 2400. Thus, the output flange 1521 in the alternative embodiment has the same circular groove as the circular groove 2130 shown in Figures 26 and 27. The circular groove of the alternative output 1500 surrounds the output shaft 1501 and includes a plurality of frustoconical surfaces that are identical to the frustoconical gear surfaces 2133, 2134 shown in Figures 26 and 27. Thus, the frustoconical surface of the output flange 1521 tapers the alternative output 1500 and axially aligns the alternative output 1500 and the input plate 2400 more closely.

[0044] Referring here to Figures 29 and 30, in a preferred embodiment, the output 1500 is provided with an output structure 1510 configured to transmit torque, and thus the output structure 1510 is provided with a non-circular radial profile 1580 including lobes. However, it should be noted that the non-circular radial profile 1580 being in the form of a gear, spline, keyway shaft, or radial screw is within the scope of the invention. As shown in Figures 29 and 30, the lobes provided with the non-circular radial profile 1580 are external lobes; preferably, the non-circular radial profile 1580 includes a plurality of lobes (referred to as the “first,” “second,” “third,” and “fourth” external lobes in Figure 30, and designated as “1581,” “1582,” “1583,” and “1584,” respectively).

[0045] Advantageously, the non-circular radial profile 1580 comprises several transition surfaces 1585, 1586, 1587, and 1588 in addition to the outer lobes 1581–188. Each of the transition surfaces 1585–1588 extends from at least one of the outer lobes 1581–1584 in a direction substantially perpendicular to the axis of the output 1501. The transition surfaces 1585–1588 generally have a flat shape, but curved shapes are also within the scope of the present invention. The output 1500 also comprises several holes (two of which are shown in Figure 32 and designated “1589” and “1590”). Extending radially inward from each of the transition surfaces 1585–1588, each of the aforementioned holes (including the holes designated “1589” and “1590” in Figure 30) is defined within the non-circular radial profile 1580 and is formed to receive fasteners, preferably socket head cap screws. Thus, each hole is threaded; however, in an alternative embodiment, the holes defined within the transition surfaces 1581–1584 are formed for pins and are therefore not threaded.

[0046] Referring here to Figures 33 and 34, the output 1500 comprises a tubular member 1595 and fasteners, ideally multiple fasteners (designated “1597-a” and “1597-b” in Figure 33). In a preferred embodiment, the tubular member 1595 is made of PEEK and has four holes, each receiving a socket head cap screw (although only two of the four socket head cap screws are visible in the perspective view of Figure 33). As previously stated, each of the four holes defined within the tubular member 1595 is dimensioned to receive one of the aforementioned socket head cap screws. The non-circular radial profile 1580 of the output 1500 is provided with threaded holes for male threaded fasteners; in a preferred embodiment, the non-circular radial profile 1580 has four threaded holes, one for each socket head cap screw, which secure the tubular member 1595 to the non-circular radial profile 1580 of the output 1500. In an alternative embodiment, the tubular member 1595 forms an integral part with the non-circular radial profile 1580 of the output 1500 (and therefore, in such an alternative embodiment, there are no holes or fasteners).

[0047] The tubular member 1595 has an outer surface 1598 that is substantially cylindrical around the axis 1596, as shown in Figure 35. As a result, the outer surface 1598 surrounds the axis 1596 and the non-circular inner surface 1599. As its name suggests, the non-circular inner surface 1599 has a main inner diameter 1576 and a secondary inner diameter 1577, as shown in Figure 36.

[0048] As also shown in Figure 36, the non-circular inner surface 1599 is configured to transmit torque; therefore, it is within the scope of the invention that the non-circular inner surface 1599 may be in the form of an internal gear, a spline sleeve, or a cylindrical surface having a keyway. Advantageously, the non-circular inner surface 1599 is formed according to a non-circular profile 1580 of output 1500. As a result, the non-circular inner surface 1599 is formed to accommodate at least one lobe, preferably multiple external lobes.

[0049] The tubular member 1595 transmits torque through one internal lobe, but it is preferable that the tubular member 1595 includes multiple internal lobes (designated as "1591", "1592", "1593", and "1594" in Figure 35) for transmitting torque. As is clear from Figure 35, each of the internal lobes 1591 to 1594 has a curved inner surface, and a preferred embodiment includes multiple curved surfaces (designated as "1571", "1572", "1573", and "1574" in Figure 36). Each of the curved surfaces 1571 to 1574 has a diameter (referred to as "lobe diameter" in Figure 36 and designated as "1578"). In a preferred embodiment, the lobe diameter 1578 is smaller than the small inner diameter 1577 of the non-circular inner surface 1599.

[0050] Referring again to Figures 33 and 34, the impactor 1000 is provided with a collision assembly 3000. As shown in both Figures 33 and 34, the collision assembly 3000 comprises several components and subassemblies, including a drive component 3100, a driven component 3200, and a shaft section 3300. The drive component 3100 includes a rolling subassembly 3110 and a non-circular rotating component 3150, and the driven component 3200 includes a stepped portion 3210 and a collision portion 3250.

[0051] Referring here to Figures 38, 39, 40, and 41, various perspective views of the non-circular rotating component 3150 and the rolling subassembly 3110 are provided, and as shown therein, the non-circular rotating component 3150 and the rolling subassembly 3110 are shown mounted to each other. Thus, torque applied to the non-circular rotating component 3150 is transmitted to the rolling subassembly 3110. As described above, the non-circular rotating component 3150 is formed according to the non-circular inner surface 1599 of the tubular member 1595. As a result, the non-circular rotating component 3150 is formed so that torque from the output 1500 is transmitted to the rolling subassembly 3110. In a preferred embodiment, torque from the output 1500 is transmitted to the rolling subassembly 3110 via the tubular member 1595 and the non-circular rotating component 3150.

[0052] The non-circular rotating component 3150 is shown in Figures 42, 43, and 44. As shown in the aforementioned figures, the non-circular rotating component 3150 is fabricated from PEEK and comprises an axis 3151, a first end face 3161, a second end face 3162, and a non-circular radial surface 3570. The non-circular radial surface 3570 extends axially from the first end face 3161 to the second end face 3162. The non-circular radial surface 3570 also extends radially from the axis 3151 and provides lobes to the non-circular rotating component 3150. Figures 42, 43, and 44 depict the non-circular radial surface 3170 with lobes, but the non-circular radial surface 3170 may take the form of a gear, spline, or keyway shaft within the scope of the invention.

[0053] In a preferred embodiment, the non-circular radial surface 3170 is shaped to provide a number of lobes 3171, 3172, 3173, and 3174 to the non-circular rotating component 3150. As previously stated, the non-circular radial surface 3170 of the rotating member 3150 is sized to cooperate with the non-circular inner surface 1599 of the tubular member 1595.

[0054] As described above, the non-circular inner surface 1599 of the tubular member 1595 transmits torque; advantageously, the internal lobes 1591, 1592, 1593, and 1594 defined within the non-circular inner surface 1599 transmit torque to the external lobes 3171, 3172, 3173, and 3174 formed on the non-circular radial surface 3170 of the rotating component 3150. As shown in Figure 45, the internal lobes 1591, 1592, 1593, and 1594 of the tubular member 1595 and the external lobes 3171, 3172, 3173, and 3174 of the rotating component 3150 are molded to maintain axial alignment (or at least substantially axial alignment) of the rotating component 3150 and the tubular member 1595 while the tubular member 1595 transmits torque to the rotating component 3150.

[0055] As shown in the cross-sectional view of output 1500 and collision assembly 3000 (see, for example, Figure 34), the rolling subassembly 3110 is attached to the rotating component 3150 via two socket head cap screws (simply referred to as “fasteners” and designated “3148” and “3149”). Thus, the non-circular rotating component 3150 has two threaded holes 3146, 3147 extending from the second end face 3162 toward the first end face 3161. The threaded holes 3146, 3147 are positioned so that the rolling subassembly 3110 is fixed to the non-circular rotating component 3150, axially aligned (or at least substantially axially aligned).

[0056] A cylindrical pocket 3145, molded to accommodate a bearing, preferably a thrust bearing (shown in Figure 34 and designated "3144"), extends from the first end face 3161 of the non-circular rotating component 3150. The bearing 3144 maintains the axial position of the drive component 3100 within the impactor 1000 while the output 1500 transmits torque.

[0057] Figures 39 and 40 show the non-circular rotating component 3150 and the rolling subassembly 3110 aligned axially. As described above and as shown in Figure 39, the rolling subassembly 3110 is fastened to the rotating component 3150 via several bolts (the bolt heads are shown in Figure 40 and designated “3148-a” and “3149-a”). As a consequence of the aforementioned bolted connection between the rolling subassembly 3110 and the rotating component 3150, several holes are defined within the rolling subassembly 3110 (hereinafter referred to as “fastening holes” and designated “3142” and “3143” in Figures 47 and 48). The fastening holes 3142 and 3143 are sized, as shown in Figure 34, for threaded shanks 3148-b and 3149-b to extend through their interiors and engage with the threads of threaded holes 3146 and 3147 defined within the non-circular rotating component 3150. As shown in Figure 48, a positional mating surface 3138 is provided on the rotating component 3150 and preferably includes a register (not shown) to ensure that the rolling subassembly 3110 remains axially aligned with the rotating component 3150 when they are fixed together.

[0058] The rolling subassembly 3110 comprises a shaft structure 3130 including rollers and shafts, the rollers being cylindrical in shape and pressed onto the shafts, as shown in Figures 46, 47, 48, and 49. The shaft structure 3130 also includes forks that hold a plurality of shafts 3132, 3133 in place. In a preferred embodiment, the shaft structure 3130 comprises a plurality of rollers (referred to as a "first" roller designated "3134" and a "second" roller designated "3135"). Each of the rollers 3134, 3135 is pressed onto each of the shafts 3132, 3133. As shown in Figure 47, the shaft structure 3130 is in the form of a plurality of forks, each fork holding one of the shafts 3132, 3133 in place with one of the rollers 3134, 3135 pressed against it.

[0059] As further shown in Figure 47, the groove 3136 effectively provides the rolling subassembly 3110 with two “forks” for the shafts 3132, 3133 and the rollers 3134, 3135. By milling or turning the groove 3136 into a block of metal, ideally titanium or an alloy such as stainless steel, the rolling subassembly 3110 is provided with walls through which radial holes 3137 can be drilled or reamed, as shown in Figure 48. The groove 3136 has a substantially rectangular cross-sectional shape, which extends into the rolling subassembly 3110 in both the axial and radial directions, housing the cylindrical rollers therein.

[0060] As shown in Figure 47, the rolling subassembly 3110 is cylindrical (and therefore has a diameter). Therefore, the groove 3136 is preferably circular with a radius (indicated as "R" in Figure 47) and includes multiple curved surfaces extending around the shaft 3131 (shown in Figure 46). As previously stated, the groove 3136 includes a substantially rectangular cross-sectional shape and provides multiple opposing walls 3121, 3122, and 3123, 3124 to the shaft structure 3130, as shown in Figures 39 and 40. The opposing walls 3121, 3122, and 3123, 3124 are spaced sufficiently apart so that the rollers can fit between them and rotate freely. It should be noted that while groove 3136 is preferably circular in shape, it may extend in a straight line or take the form of a square or rectangle, and can provide a pair of opposing walls 3121, 3122 and 3123, 3124 to the rolling subassembly 3110.

[0061] As described above, the positional mating surface 3138 of the rolling subassembly 3110 is fixed to the second end face 3162 of the non-circular rotating component 3150 (which rotates itself by the tubular member 1595). To ensure that the non-circular rotating component 3150 and the rolling subassembly 3110 are axially aligned when fixed to each other, the second end face 3162 is provided with a register (not shown), which is in the form of a cylindrical blind hole defined within the non-circular rotating component 3150. The register has a diameter that is dimensioned so that the diameter of the rolling subassembly 3110 can be bolted therein.

[0062] As described above, the rolling subassembly 3110 is fixed to the non-circular rotating component 3150; since the non-circular rotating component 3150 is rotated by the tubular member 1595, the rolling subassembly 3110 also rotates while at least one of the rollers 3134, 3135 is in contact with the stepped portion 3210 of the driven component 3200. In a preferred embodiment, all of the rollers 3134, 3135 are in contact with the stepped portion 3210 of the driven component 3200 while rotating about the axis 3201 (shown as a “dot” in the circle in Figure 52). Thus, the driven component 3200 comprises roller bearing surfaces, preferably a plurality of roller bearing surfaces 3228, 3229.

[0063] As its name suggests, the stepped portion 3210 of the driven component 3200 comprises steps; in a preferred embodiment, the stepped portion 3210 comprises a plurality of steps 3211, 3212, 3214, and 3215, as shown in Figure 52. Advantageously, as shown in Figure 50, the steps 3211, 3212, 3214, and 3215 are connected to form smooth-profile inclined portions 3216 and 3217. Each of the inclined portions 3216 and 3217 extends at an angle 3230 from one of the roller bearing surfaces 3228 and 3229 and abuts against the top surface 3213. In a preferred embodiment, the angle 3230 is 135°; however, in an alternative embodiment, the angle 3230 is between 90° and 160° (including both ends).

[0064] As shown in Figure 52, each of the inclined portions 3216 and 3217 extends both radially from the shaft 3201 and axially from the roller bearing surfaces 3228 and 3229, respectively (as described above). By extending both axially and radially, the inclined portions 3216 and 3217 in the preferred embodiment form a helical portion around the shaft 3201, similar to the threads of a threaded component. As shown in Figure 50, each of the inclined portions 3216 and 3217 inclines upward from the roller bearing surfaces 3228 and 3229, respectively, and terminates at the top surface 3213 to form a set of inclined portions 3216 and 3217.

[0065] The pitch of the inclined sections 3216 and 3217 is dimensionally determined according to the outer diameter of the driven component 3200, the diameter and width of the rollers 3134 and 3135, the desired axial stroke length of each impact generated by the impactor 1000, and the number of impacts that the impactor 1000 delivers for each rotation of the rotor 1320. In a preferred embodiment, it is desirable that the impactor 1000 delivers impacts with a stroke length of 0.0625 inches, and that two such impacts are delivered per revolution of the motor 1300. Therefore, it is preferable that the stepped section 3210 of the driven component 3200 comprises a plurality of roller bearing surfaces, a plurality of top surfaces, and a plurality of inclined section sets connecting the roller bearing surfaces and the top surfaces.

[0066] Figure 52 shows a stepped portion 3210 of a driven component 3200, which has two sets of inclined sections (hereinafter referred to as the “first” set of inclined sections designated “3216” and “3217”, and the “second” set of inclined sections designated “3226” and “3227”) to provide two impacts per revolution of the rotor 1320. The two sets of inclined sections 3216, 3217 and 3226, 3227 connect two roller bearing surfaces and two top surfaces (hereinafter referred to as the “first” top surface designated “3213”, and the “second” top surface designated “3223”, and are distinguished from each other).

[0067] The second inclined section sets 3226, 3227 include multiple steps 3221, 3222, 3224, 3225, which are connected to form smooth-profile inclined sections 3226, 3227, similar to the first inclined section sets 3216, 3217 shown in Figure 50. Similar to the first inclined section sets 3216, 3217 that “go up” and “go down” to the first inclined section 3213, the second inclined section sets 3226, 3227 also “go up” and “go down” to the second inclined section 3223. Each of the second inclined section sets 3226, 3227 extends axially and radially from one of the roller bearing surfaces 3228, 3229 to form an angle 3230, and each of the second inclined section sets abuts against the second top surface 3223.

[0068] The angle 3230 formed between each of the inclined portions 3226 and 3227 and each of the roller bearing surfaces 3228 and 3229 is 135° (however, in alternative embodiments, the angle 3230 is 90° to 160°, including both ends). As described above, each of the inclined portions 3226 and 3227 extends radially from the shaft 3201 and axially from each of the roller bearing surfaces 3228 and 3229, forming a helical portion around the shaft 3201. It is preferable that the inclined portions 3226 and 3227 extend helically from the roller bearing surfaces 3228 and 3229 to the top surfaces 3213 and 3223, but it should be noted that other stepped profiles (such as linear inclined portion profiles) are also within the scope of the present invention.

[0069] Referring again to Figure 52, steps 3211, 3212, 3221, and 3222 (and thus inclined sections 3216, 3226 and top surfaces 3213, 3223) are positioned 180° from each other. Similarly, steps 3214, 3215, and 3224, 3225 (and thus inclined sections 3217, 3227) are also positioned 180° from each other. As a result, when the rolling subassembly 3110 is rotated counterclockwise on the stepped portion 3210 of the driven component 3200, the first roller 3134 rolls on the steps 3211, 3212 (and thus the first inclined portion 3216) and reaches the first top surface 3213, while simultaneously (or at least substantially simultaneously), the second roller 3135 rolls on the steps 3221, 3222 (and thus the second inclined portion 3226) and reaches the second top surface 3223. Thus, the rollers 3134 and 3135 of the rolling subassembly 3110 deliver the impact that is transmitted axially to the impact portion 3250 of the driven component 3200.

[0070] As described above, it is desirable that the impactor 1000 delivers impacts with a stroke of 0.0625 inches; also as described above, the two sets of inclined sections 3216, 3217 and 3226, 3227 extend axially from the roller bearing surfaces 3228, 3229 to "go up" and "go down" to the top surfaces 3213, 3223. Furthermore, as described above, the impactor 1000, which constitutes the currently preferred embodiment, provides two impacts per revolution of the motor 1300 as the rollers 3134, 3135 wind up the two sets of inclined sections 3216, 3217, 3226, 3227 and go over the two top surfaces 3213, 3223. Therefore, in order to provide impact with a stroke of 0.0625 inches, the inclined sections 3216, 3217, 3226, and 3227 extend 0.0626 inches axially from the roller bearing surfaces 3228, 3229 to the top surfaces 3213, 3223.

[0071] Referring here to Figures 53, 54, and 56, it is desirable that the stepped portion 3210 and the impact portion 3250 of the driven component 3200 remain axially aligned (or at least substantially axially aligned); as a result, the stepped portion 3210 and the impact portion 3250 each comprise a mating surface referred to as a “stepped” mating surface 3218 (which is provided on the “stepped” portion 3210 of the driven component 3200) and a “impact” mating surface 3219 (which is provided on the “impact” portion 3250 of the driven component 3200). In a preferred embodiment, the impact mating surface 3219 also functions as an inner surface 3252, as shown in Figure 57.

[0072] The mating surfaces 3218 and 3219 are dimensioned relative to each other to allow for press-fitting, as shown in Figure 56. In a preferred embodiment, the mating surfaces 3218 and 3219 are cylindrical in shape, with each mating surface having a diameter; the diameter of the stepped mating surface 3218 is 0.001 to 0.005 inches (including both ends) smaller than the diameter of the impact mating surface 3219.

[0073] Referring again to Figure 52, the stepped portion 3210 of the driven component 3200 includes a non-circular bore 3202 that accommodates the shaft section 3300 and is shaped to prevent rotation of the stepped portion 3210. In a preferred embodiment, the non-circular shape is square (with rounded corners); however, in an alternative embodiment, the non-circular shape is a keyway, ellipse, or polygonal shape such as hexagon or rectangle. Thus, the stepped portion 3210 of the driven component 3200 is prevented from rotating even as the rolling subassembly 3110 rotates and the rollers 3134, 3135 roll over the steps 3211, 3212, 3214, 3215, 3221, 3222, 3224, 3225 and top surfaces 3213, 3223.

[0074] As shown in Figure 34, the stepped portion 3210 is secured to the impact portion 3250 via pins, preferably a plurality of pins 3261, 3262, and extends from the outer surface 3251 to the inner surface 3252 of the impact portion of the driven component 3200 (shown in Figure 57). As shown in the cross-sectional view of the stepped portion 3210 in Figure 54, the pins 3261, 3262 further extend through fastening holes 3263, 3264 defined within the stepped portion 3210. The fastening holes 3263, 3264 of the stepped portion 3210 extend radially from a non-circular bore 3202 to the stepped mating surface 3218.

[0075] Pins 3261 and 3262 extend through fastening holes 3263 and 3264 defined within the stepped portion 3210 into holes 3265 and 3266 defined within the impact portion 3250 of the driven component 3200. To accommodate the pins 3261 and 3262 extending from holes 3263 and 3264 in the stepped portion 3210, holes 3265 and 3266 defined within the impact portion 3250 are molded to extend radially from the inner surface 3252 of the impact portion 3250, as shown in Figures 57-a and 57-b. The inner surface 3252 of the impact portion 3250 is dimensioned to accommodate the spring 3240 and, in a preferred embodiment, is generally cylindrical in shape.

[0076] The outer surface 3251 of the impact portion 3250 is cylindrical (and therefore has a circular cross-sectional shape); however, in alternative embodiments, the outer surface 3251 has a non-circular shape, such as an octagonal or hexagonal cross-sectional shape. In preferred embodiments, the outer surface 3251 is dimensioned to provide the impact portion 3250 with an "impact" bearing surface 3255, which is in the form of an annular surface located at one of two ends 3256, 3257 (referred to as the "stepped" end and the "instrument" end, respectively). The impact bearing surface 3255 is located at the stepped end 3256 of the impact portion 3250 (the stepped end 3256 facing the "stepped" portion 3210 is referred to to distinguish it from the instrument end 3257, which has a screw hole 3258 for mounting a surgical "instrument," such as a broach, bone compression tool, or other instrument).

[0077] As shown in Figure 57-b, the impact bearing surface 3255 contacts the outer surface 3251 and inner surface 3252 of the impact portion 3250. As described above, the second bearing surface 3238 of the stepped portion 3210 contacts the impact bearing surface 3255 of the impact portion 3250 of the driven component 3200.

[0078] Referring again to Figures 57-a and 57-b, the noncircular bore 3202 extends axially through the stepped portion 3210 and is molded to accommodate the shaft section 3300, which has a noncircular cross-sectional shape. The shaft section 3300 (shown in cross-section in Figure 57-b) conforms to the radial shape of the noncircular bore 3202, thereby preventing torsional motion of the stepped portion 3210 (and thus torsional motion of the impact portion 3250 pinned to the stepped portion 3210). Thus, as described above, the shaft section 3300 is molded so that the stepped portion 3210 moves axially along the length of the shaft section 3300, while the noncircular cross-sectional shape of the shaft section 3300 prevents rotation of the stepped portion 3210.

[0079] Referring here to Figure 58, the shaft section 3300 comprises a shaft 3301, a bearing surface 3302, a flange 3303, a slot 3305, and an end 3304 (referred to as the “spring” end to distinguish it from other ends disclosed herein, as it has a spring 3240). The slot 3305 extends through the shaft section 3300 to accommodate a pin 3267 (as shown in Figures 57-b and 56). As shown above, the pin 3267 extends through the slot 3305 and through a hole 3268 defined in the stepped portion 3210 of the driven component 3200. Thus, the slot 3305 extends radially, preventing torsional motion while simultaneously allowing the pin 3267 to move axially within the slot 3305 during the operation of the impactor 1000.

[0080] As seen in Figures 55 and 56, the shaft section 3300 extends through a passage 3102 defined within the drive component 3100. The passage 3102 is dimensioned to provide clearance for the drive component 3100, and therefore for the non-circular rotating component 3150 and rolling subassembly 3110 that rotate around the shaft section 3300. Thus, when the impactor 1000 is actuated, the shaft section 3300 screws onto the shaft 2500 and does not rotate, while the tubular member 1595 attached to the output 1500 rotates the drive component 3100 (and therefore for the non-circular rotating component 3150 and rolling subassembly 3110). As the rollers 3134 and 3135 of the rolling subassembly 3110 roll "up" on the inclined section and pass the top surfaces 3213 and 3223 of the stepped portion 3210 of the driven component 3200, the stepped portion 3210 is forced to move axially along the shaft section 3300 (as well as the first and second bearing surfaces 3238 and 3239 located on the outer surface of the stepped portion 3210). The first bearing surface 3238 of the stepped portion 3210 contacts the impact bearing surface 3255 of the impact portion 3250 of the driven component 3200, so the impact portion 3250 is forced to move axially.

[0081] As the second bearing surface 3239 contacts the spring 3240, the axial motion of the stepped portion 3210 compresses the spring 3240. As the rollers 3134 and 3135 roll "down" along the inclined portion from the top surfaces 3213 and 3223 to the roller bearing surfaces 3228 and 3229, the spring 3240 exerts force on the second bearing surface 3239 of the stepped portion 3210, thereby moving the stepped portion 3210 axially toward the flange 3303 of the shaft section 3300. Thus, the spring 3240 axially positions the stepped portion 3210 on the shaft section 3300, thereby causing the rollers 3134 and 3135 to contact the roller bearing surfaces 3228 and 3229 as the rotating component 3150 rotates around the shaft section 3300, impacting the step (and therefore the inclined portion).

[0082] As is evident from the cross-sectional views of the shaft section 3300 and the drive and driven components 3100 and 3200 in Figures 34 and 56, the spring 3240 abuts against the second bearing surface 3239 of the stepped portion 3210 and the flange 3307 (referred to here as the “spring” flange to distinguish it from other flanges disclosed herein). The spring flange 3307 is attached to the shaft section 3300 via bolts 3306 and threaded holes 3308 machined into the shaft section 3300. While preferred embodiments are shown using bolted attachment, alternative embodiments utilize welding or adhesive attachment between the shaft section 3300 and the spring flange 3307.

[0083] Referring here to Figures 61 to 65, an impactor 1000 is preferably shown comprising a housing 1100 and a motor mounting component 2520 including a battery receptacle 2530. The housing 1100 comprises a number of flats 1106 and blind screw holes 1107 defined therein for mounting a cylindrical handle, a housing shaft 1101, a first housing end 1110 terminating at a first housing opening 1111, and a second housing end 1120 terminating at a second housing opening 1122. The inner housing surface 1105 extends axially within the housing 1100 from the first and second housing openings 1111, 1122. The inner housing surface 1105 is shaped and dimensional such as to provide a proper fit between the housing 1100 and the various components and assemblies described herein.

[0084] As shown in Figures 62 and 63, the first inner housing surface 1113 extends axially from the first housing opening 1111 and is dimensioned to provide a sliding fit with the outer surface 3251 of the impact portion 3250 (i.e., to allow the impact portion 3250 to slide axially back and forth); as a result, in a preferred embodiment, the first inner housing surface 1113 has a diameter dimensioned to be 0.001 inches to 0.005 inches (including both ends) larger than the diameter of the outer surface 3251 of the impact portion 3250.

[0085] Figure 62 also shows a second inner housing surface 1123 extending axially from a second housing opening 1122; the second inner housing surface 1123 is dimensioned to press-fit with an outer cylindrical surface 2528 located on the motor mounting component 2520 (as shown in Figure 63). A third inner housing surface 1133 is located within the inner surface 1105 of the housing 1100 between the first inner housing surface 1113 and the second inner housing surface 1123. The third inner housing surface 1133 extends axially within the housing 1100 and provides press-fitting of the ring gear 2300 with the outer ring surface 2303 to the impactor 1000.

[0086] In a preferred embodiment, the battery receptacle 2530 is attached to a motor mounting component 2520, as shown in Figures 66–71. At one end (referred to as the “motor end” and designated “2522” in Figures 66, 69, 71, and 73), the motor mounting component 2520 includes a register 2524 for the stator 1310 and a number of through holes 2525, 2526 for mounting the stator 1310 and shaft 2500 of the motor 1300. The register 2524 is in the form of a shallow cylindrical pocket that aligns the shaft 1301 of the motor 1300 with the shaft 1101 of the housing 1100. The motor mounting component 2520 also includes a slot 2527 for conductors extending from the stator 1310 to a motor controller 1350 located within the battery receptacle 2530. The motor mounting component 2500 also includes grooves (preferably multiple grooves 2521, 2529) for electrical wiring; advantageously, after the wiring is inserted into the grooves 2521, 2529, the grooves 2521, 2529 are filled with silicone rubber or RTV rubber to prevent water ingress.

[0087] The battery receptacle 2530 located at the end opposite the motor end 2522 (referred to as the "battery end" and designated as "2523") is provided with a sealing structure 2535, which is in the form of a thread (preferably multiple turns of a coarse thread such as UNC4-4). Extending from the first opening 1111, the housing 1100 is provided with a housing sealing structure 1115, which is also in the form of a thread (preferably multiple turns of a coarse thread such as 2-4 1 / 2UNC).

[0088] In a preferred embodiment, since the sealing structures 1115, 2535 (referred to as the “first” sealing structure 1115 and the “second” sealing structure 2535, and distinguished from each other) employ multiple coarse threads, the impactor 1000 comprises threaded caps 1117, 2537 (shown in Figures 74-79). The caps 1117, 2537 seal the inner housing surface 1105 from water ingress, thereby allowing the impactor 1000 to be immersed in water for cleaning and subsequent sterilization. It is advantageous for the impactor 1000 to include a threaded sleeve to protect the threads of the sealing structure 1115 during use of the impactor 1000.

[0089] From the sealing structure 2535, the battery receptacle 2530 extends axially toward the motor end 2522. The battery receptacle 2530 is dimensioned so that the battery 2540 can be centrally positioned within the housing 1100 and slidably fixed within the housing 1100, as shown in Figures 64 and 65. The battery receptacle 2530 terminates adjacent to the motor mounting component 2520 where the motor controller 1350 is located. Advantageously, a spring load pin is incorporated within the motor controller 1350, the motor controller 1350 is positioned within the battery receptacle 2530, and the battery receptacle 2530 aligns the spring load pin with the contacts on the battery 2540. After the battery 2540 is placed inside the housing 1100, the sealing cap 2537 (shown in Figures 74-76) is placed on the sealing structure 2535 to secure the battery 2540 to the pins inside the housing 1100.

[0090] To assemble the impactor 1000 within the housing 1100, the shaft 2500 is attached to the motor mounting component 2520 via a number of bolts extending through holes 2526 in the motor mounting component 2520. The stator 1310 is then attached to and aligned with the motor mounting component 2520 via a number of bolts extending through holes 2525 in the motor mounting component 2520. Next, the sun gears 2100-a and 2100-b, having the input plate and rotor 1320, are positioned on the shaft 2500 such that the rotor 1320 extends radially around the stator 1310. The output 1500 and tubular member 1595 are then assembled on the shaft 2500, and the shaft section 3300, on which the drive and driven components 3100 and 3200 are assembled, is fastened to the threaded end of the shaft 2500. After assembling the motor 1300 and motor mounting component 2520, shaft 2500, gear train 2000, output unit 1500, and shaft section 3300 together with the collision assembly 3000, the assembly is placed inside the housing 1100. As described above, the outer cylindrical surface 2528 of the motor mounting component 2520 is dimensionally determined to press-fit with the second inner housing surface 1123 of the housing 1100.

[0091] Referring here to Figures 80-88, the impactor 1000 is provided with a handle 1200. The handle comprises two plates (a trigger plate and a support plate), a handle body, a trigger component, a support component, a switch, a bracket, and a cover. The trigger plate 1220 has two ends (referred to as the first trigger end 1221 and the second trigger end 1222); similarly, the support plate 1230 has two ends (referred to as the first support end 1231 and the second support end 1232). Like plates 1220 and 1230, the handle body 1240 also has two ends (referred to as the first body end 1241 and the second body end 1242).

[0092] Plates 1220 and 1230 are titanium (or stainless steel as an alternative) and are rounded to provide the handle 1200 with a cylindrical shape having a diameter of 1.20 to 2.1 inches, preferably 1.5 inches. To accommodate the width of a human hand, plates 1220 and 1230 have a length of 3.5 inches or more; in a preferred embodiment, the trigger plate 1220 is 4.5 inches and the support plate 1230 is 6.025 inches.

[0093] The first and second support components 1261 and 1262 are attached to the first and second body ends 1241 and 1242 via a plurality of fasteners 1243 and 1244 (as shown in Figure 86). The first and second trigger components 1251 and 1252 are attached to the trigger ends 1221 and 1222 via a plurality of fasteners 1293 and 1294 and a rectangular rod 1253 (as shown in Figure 81). Each of the trigger components 1251 and 1252 is provided with a pair of grooves 1254 and 1255, which allow each of the trigger components 1251 and 1252 to be slidably fixed to each of the handle body ends 1241 and 1242.

[0094] Switch 1270 (shown on circuit board 1272 and insulated with conformal coating) is a single-pole, single-throw, normally open, instantaneous tact switch housed and supported in at least one of the support components 1261, 1262. Switch 1270 has a dust and water protection rating of 67 (i.e., an IP rating of 67) and has operating and storage temperatures up to 125°C. To activate the impactor 1000, switch 1270 must be actuated by pressing the trigger plate 1220 and the support plate 1230 together. Since each of the trigger components 1251, 1252 is slidably fixed to each of the body ends 1241, 1242, trigger component 1250 slides toward one of the support components 1261, 1262 and toward at least one switch 1270 housed therein. As shown in Figure 83, the switch 1270 has sufficient clearance to extend beyond the support component, and when the plates 1220 and 1230 are pressed together, at least one of the trigger components 1251 and 1252 pushes down the actuator 1271 of the switch 1270.

[0095] A pair of compression springs apply force to the rectangular rod 1253, orienting the trigger component away from the actuator 1271 on the switch 1270, thereby returning the actuator 1271 to the open position and turning off the impactor 1000. As a result, the surgeon must overcome the spring force to close the switch 1270 and turn on the impactor 1000, or simply release the trigger plate 1220 to turn off the impactor 1000. To maintain the orientation of the springs, the rectangular rod 1253 is provided with a pair of counterbore holes 1246, 1247 defined within the handle body 1240 and a number of axially aligned pins 1256, 1257. The springs are positioned to surround the pins 1256, 1257 while simultaneously fitting into the counterbore holes 1246, 1247. Thus, when the trigger plate 1220 is compressed toward the support plate 1230 and then released, the axial orientation of the springs is maintained.

[0096] The handle 1200 is secured to the housing 1100 at a second end 1120 via a pair of brackets 1281 and 1282. As shown in Figures 63 and 88, each of the brackets 1281 and 1282 is attached to the housing 1100 such that the handle 1200 extends radially from the axis 1101 of the housing 1100; thus, by gripping the handle 1200, the surgeon's arm is aligned with the axis 1101, allowing for more precise positioning of the impactor 1000, and the force generated by the impactor 1000 can be supported by the surgeon's larger arm and pectoral muscles rather than the surgeon's wrist (as in the case of a pistol-grip power tool).

[0097] As described above, the handle 1200 includes a tact switch 1270 located within at least one of the support components 1261, 1262. To reach at least one of the switches located within the handle 1200, electrical wiring is routed from within the housing 1100 through at least one of the brackets 1281, 1282 to at least one of the support components 1261, 1262. To prevent water and foreign matter from entering the brackets 1281, 1282, the handle 1200 includes a cover, preferably a pair of covers 1291, 1292 (one for each of the brackets 1281, 1282). To further prevent water and foreign matter from entering, the plates 1220, 1230 are overmolded with silicone rubber or neoprene.

[0098] While the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that various forms of variations and details are possible without departing from the spirit and scope of the invention as described in the claims.

Claims

1. An electrically driven impactor suitable for use in surgical procedures, a) Housing; b) A brushless DC motor including a stator having multiple coils and a rotor having multiple magnets; c) A motor controller equipped with a motor driver that supplies current to the coils of the stator to rotate the rotor around the stator; d) A planetary gear train comprising an input, a sun gear, planetary gears, a ring gear, and an output; e) A shaft including a shaft section having a non-circular cross-sectional shape; f) Collision assembly including drive component and driven component Equipped with, i) The drive component has a defined passage inside, providing clearance for non-circular rotating components and rolling subassemblies, (1) The non-circular rotating component is attached to the rolling subassembly; (2) The non-circular rotating component and the rolling subassembly are rotated by the output of the gear train; (3) The rolling subassembly comprises a plurality of shafts, rollers, and forks, each of the rollers being pressed against each of the shafts, and each of the shafts being press-fitted into each of the forks, ii) The driven component includes a collision portion and a stepped portion in which a non-circular bore is defined inside, (1) The shaft section having a non-circular cross-sectional shape extends through the non-circular bore; (2) The stepped portion further includes a first roller bearing surface, a second roller bearing surface, a top surface, a first inclined portion, and a second inclined portion, each of which extends radially from the noncircular bore; (3) The first inclined portion extends axially from the first roller bearing surface to the top surface, and the second inclined portion extends axially from the second roller bearing surface to the top surface; (4) The top surface is located between the first roller bearing surface and the second roller bearing surface, iii) The roller of the rolling subassembly rotates on the first roller bearing surface, raising the first inclined portion to the top surface, and then descending the second inclined portion and rotating to the second roller bearing surface. An impactor characterized by the following features.

2. The impactor according to claim 1, characterized in that the sun gear, the planetary gear, and the ring gear are made from PEEK.

3. The impactor according to claim 1, characterized in that the stepped portion is made from PEEK.

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