Electric tool and mode switching mechanism therefor

Abstract

A mode switching mechanism for an electric tool, and an electric tool. The mode switching mechanism enables the electric tool to comprise two motion modes, namely, an eccentric motion mode and a concentric motion mode. The mode switching mechanism comprises: a transmission shaft (25) having a first axis (X1) and a toothed section (28); a ring gear (40) and a planet carrier (50) which are arranged coaxially with the transmission shaft; an output shaft (35), which is mounted on the planet carrier and can rotate around a second axis (X2) offset from the first axis; a counterbalance (70), which is fixed to the planet carrier and for which the center of mass is offset in a direction opposite to a radial direction from the first axis to the second axis; and a planetary gear (60), which is fixed to the output shaft and meshes with both the toothed section and the ring gear. In the eccentric motion mode, the ring gear (40) is engaged by a brake member of a mode selection device of the electric tool and is prevented from rotating around the first axis; and in the concentric motion mode, the planet carrier (50) is engaged by the brake member and is prevented from rotating around the first axis. The electric tool can provide two motion modes, namely, a concentric motion mode and an eccentric motion mode, and dynamic balance is easily maintained when switching between the two motion modes.

Description

Power tool and mode switching mechanism thereof Technical Field

[0001] The present invention relates to a mode switching mechanism for an electric tool and an electric tool comprising the mode switching mechanism. More specifically, the present invention relates to a dual-mode electric grinding or polishing tool having a straight-center motion mode and an eccentric motion mode. Background Art

[0002] Electric grinding and polishing tools are a kind of commonly used electric tools, which can perform tasks such as grinding and sanding on the surface of materials.

[0003] In particular, the use of polishers for repairing and polishing car paintwork is a common practice in the automotive industry. A straight-center polisher is particularly effective for paint repair, as it can effectively remove deeper scratches. However, it can sometimes over-polish, which can cause glare marks on the paint surface. An eccentric polisher is suitable for waxing and polishing, creating a brighter finish and effectively removing glare marks and sun streaks.

[0004] Currently, some polishers on the market can only provide one of the above modes and cannot cover all application scenarios. There are also some polishing machine products that can achieve two eccentric motion modes, but cannot provide the functions of a straight polisher and cannot cover the application scenarios of a straight polisher.

[0005] The difficulty in switching between straight and eccentric motion modes on the same polishing machine lies in the fact that these two motion modes correspond to two different dynamic balance states, and dynamic balance must be achieved in both modes. In particular, to achieve dynamic balance in the eccentric motion mode, the polishing machine typically requires a large balancing block. When the polishing machine switches between straight and eccentric motion modes, the large balancing block needs to move accordingly to provide completely different balancing dynamics (forces / actions). This poses significant challenges to the stability of the polishing machine's internal components, the fitting tolerances between parts, and the dynamic balancing effect.

[0006] Summary of the Invention

[0007] The object of the present application is to overcome at least one of the above mentioned drawbacks.

[0008] In a first aspect of the present application, a mode switching mechanism for an electric tool is provided, which has an eccentric configuration and a straight-center configuration and includes: a transmission shaft, which includes a toothed segment with external teeth and is configured to rotate about its own first axis when driven by the motor of the electric tool; an inner gear ring arranged coaxially with the transmission shaft; a planetary carrier arranged coaxially with the transmission shaft; an output shaft, which is mounted to the planetary carrier and can rotate about its own second axis relative to the planetary carrier, the second axis being parallel to the first axis and arranged from it in a first radial direction; a balancing weight fixed to the planetary carrier, the center of mass of the balancing weight being oriented from the first axis along the same radial direction as the first axis; The gears are offset in a second radial direction opposite to the first radial direction; and a planetary gear is coaxial with the output shaft and relatively fixedly mounted thereon, and meshes with both the toothed segment and the inner ring gear; in the eccentric configuration, the inner ring gear is engaged by a braking member of a mode selection device of the power tool and is prohibited from rotating about a first axis, so that the planetary gear and the output shaft rotate about the second axis while rotating about the first axis together with the planetary carrier and the balance weight; in the straight-center configuration, the planetary carrier is engaged by the braking member and is prohibited from rotating about the first axis, so that the planetary gear and the output shaft rotate only about the second axis.

[0009] In one embodiment, the toothed segment is an integrally formed shaft segment of the transmission shaft, or is a separately provided gear wheel fixed to the transmission shaft.

[0010] In one embodiment, the ring gear and the planet carrier include a ring gear clearance and a planet carrier clearance, respectively, configured to receive at least a portion of the brake member.

[0011] In one embodiment, the inner gear ring has an end surface and a plurality of protrusions protruding from the end surface and arranged at intervals in a circumferential direction, with adjacent protrusions defining inner gear ring gaps therebetween.

[0012] In one embodiment, each protrusion has an inclined end surface away from the end surface, the end surface having a front edge and a rear edge in the rotation direction of the inner gear ring, and the distance between the front edge and the end surface is smaller than the distance between the rear edge and the end surface.

[0013] In one embodiment, the planet carrier includes a base plate and a first flange and a second flange extending in opposite directions from the base plate in an axial direction, and the planet carrier gap is formed on an end surface of the first flange.

[0014] In one embodiment, two planet carrier gaps arranged opposite to each other in a diameter direction are formed on the end surface of the first flange.

[0015] In one embodiment, the diameter direction defined by the two planet carrier gaps is perpendicular to a plane defined by the first axis and the second axis.

[0016] In one embodiment, the end surface between the two planet carrier gaps is axially inclined toward the base plate in the rotation direction of the two planet carriers.

[0017] In one embodiment, the balancing weight is fixed to the planet carrier by at least one of bolt connection, welding, clamping, and form fit.

[0018] In one embodiment, the balancing weight includes a first balancing weight and a second balancing weight respectively fixed to two surfaces of the base plate that are opposite in the axial direction.

[0019] In one embodiment, the center of mass of the planet carrier on the side where the balancing weight is located and the center of mass of the planet carrier on the side where the output shaft is located are located in the same plane perpendicular to the first axis.

[0020] In a second aspect of the present application, there is provided an electric tool having a straight-center motion mode and an eccentric motion mode, and comprising: a transmission housing; the above-mentioned mode switching mechanism, which is accommodated in the transmission housing, and the output shaft of the mode switching mechanism extends from the transmission housing; and a mode selection device mounted on the transmission housing, the mode selection device comprising: a selection housing configured to be rotatably mounted on the transmission housing; the brake member, and at least a portion of the brake member is configured to selectively engage with one of the inner gear ring and the planetary carrier of the mode switching mechanism; and an operating member, which is mounted on the selection housing and configured To be operated by an operator, the operating member includes a housing engagement portion and an engagement end configured to engage with the brake member, and the operating member is configured such that: in a first position not operated by the operator, the housing engagement portion engages with the transmission housing to prevent the selection housing from rotating relative to the transmission housing, and the engagement end engages with the brake member to place the at least one portion thereof in a state of engagement with one of the ring gear and the planet carrier; and in a second position operated by the operator, the housing engagement portion is disengaged from the transmission housing to allow the selection housing and the transmission housing to rotate, and the engagement end is disengaged from the brake member.

[0021] In one embodiment, when the operating member is in the second position, the braking member is still in a state where the at least one portion is engaged with one of the ring gear and the planet carrier.

[0022] In one embodiment, the brake member includes a body and a tab extending from the body, the tab being the at least one portion.

[0023] In one embodiment, the body includes opposing annular portions and two opposing straight portions connecting the opposing annular portions, and in the first position of the operating member, the engaging end contacts and pushes against one of the two opposing straight portions, and in the second position of the operating member, the engaging end does not contact either of the two opposing straight portions.

[0024] In one embodiment, the selection housing includes a base, a protrusion extending from a first side of the base and adapted to be rotated by an operator, and an annular portion extending from an opposite second side of the base, and the operating member includes an operating portion extending from the protrusion to be operated by the operator between a first position and a second position.

[0025] In one embodiment, the mode selection device further includes a biasing spring disposed in the protrusion, one end of the biasing spring abutting against the selection housing, and the other end being received in a cavity formed in the operating portion of the operating member to maintain the operating member in the first position when the operating member is not operated.

[0026] In one embodiment, the transmission housing includes an annular portion, which includes two cutouts arranged opposite to each other in the diameter direction and configured to receive the housing engagement portion, wherein in the first position of the operating member, the housing engagement portion engages one of the two cutouts, and in the second position of the operating member, the housing engagement portion does not engage either of the two cutouts.

[0027] In one embodiment, the power tool is a power polishing tool.

[0028] In one embodiment, a motor is further included, wherein the rotation axis of the motor shaft of the motor is perpendicular to the first axis and the second axis, and the mode selection device is provided on either side of the transmission housing relative to the rotation axis.

[0029] In one embodiment, a polishing base plate is further included, which is fixedly mounted to the output shaft of the mode switching mechanism.

[0030] The power tool of the present application has a mode switching mechanism (or transmission device) disposed between a motor for providing driving force and a tool for operating a workpiece (e.g., a polishing base plate). The mode switching mechanism includes: a transmission shaft driven by the motor; an output shaft parallel to and eccentrically disposed with the transmission shaft; and a planetary device disposed between the transmission shaft and the output shaft. The planetary device includes planetary gears driven to rotate by the transmission shaft and mounted on the output shaft for synchronous rotation therewith; an inner ring gear and a planetary carrier coaxially disposed with the transmission shaft; and a balancing weight fixed to the planetary carrier in a radially opposite offset manner relative to the output shaft with respect to the central axis of the transmission shaft. The output shaft is mounted to the planetary carrier for relative rotation. A brake member of the power tool's mode selection device selectively engages one of the inner ring gear and the planetary carrier.

[0031] The brake member of the mode selection device prohibits the inner ring gear from rotating around the central axis of the transmission shaft when the inner ring gear of the mode switching mechanism is engaged. At this time, while the output shaft rotates around its own axis, the planetary carrier (and the output shaft and the balance block mounted thereon) rotate (revolve) around the central axis, so that the mode switching device provides an eccentric configuration and the polishing machine is in an eccentric motion mode; the brake member prohibits the planetary carrier (and the output shaft and the balance block mounted thereon) from rotating around the central axis of the transmission shaft when the planetary carrier is engaged, and the output shaft only rotates around its own axis, so that the mode switching device provides a straight-center configuration and the polishing machine is in a straight-center motion mode.

[0032] The polishing machine of the present application can provide two motion modes, straight and eccentric, and is therefore applicable to all application scenarios corresponding to these two motion modes. When switching between the two motion modes, the components of the polishing machine's transmission mechanism, especially the large-mass balancing block, do not need to move. This, on the one hand, ensures the dynamic balancing effect of the power tool in both motion modes, especially the eccentric motion mode. On the other hand, because the switching of motion modes only requires the operator to operate the operating member of the mode selection device and does not require any movement of the internal moving parts, the impact of frequent switching of motion modes on the performance or life of the polishing machine is minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is a schematic diagram of a power tool according to the present application, wherein a mode selection device of the power tool is removed from the power tool.

[0034] FIG2 is an exploded view of the transmission portion of the power tool of FIG1 , wherein the transmission portion includes the mode switching mechanism of the present application.

[0035] FIG3 is an assembly diagram of the transmission part, wherein the transmission part is partially cut away to reveal the internal structure.

[0036] FIG4 is a cross-sectional view of the transmission portion.

[0037] FIG. 5 is a parts diagram of the inner ring gear of the mode switching mechanism.

[0038] FIG6 is a parts diagram of the planetary carrier of the mode switching mechanism.

[0039] FIG7 is a schematic diagram showing the transmission part of the electric tool from another angle, showing the annular portion on the transmission part housing for mounting the mode selection device.

[0040] FIG8 is an exploded view of the mode selection device.

[0041] FIG. 9 is an assembly diagram of the mode selection device.

[0042] FIG. 10 is a schematic diagram of the mode switching mechanism of the electric tool in the eccentric motion mode.

[0043] FIG. 11 is a schematic diagram of the mode switching mechanism of the electric tool in the straight-center motion mode. DETAILED DESCRIPTION

[0044] This application relates to a power tool with two motion modes: a linear (or rotational) motion mode and an eccentric (or orbital) motion mode, as well as a mode switching mechanism capable of achieving these two motion modes. The power tool with these two motion modes may be, but is not limited to, a common grinder, polisher, or the like. This application will use a polisher as an example for illustration.

[0045] The polishing machine includes a motor for providing driving force, a tool (or grinding or polishing plate) for performing grinding or polishing operations on the surface of a workpiece, and a transmission device arranged between the motor and the tool for transmitting the driving force (or motion) of the motor to the tool, which is also referred to herein as a mode switching mechanism. The polishing machine of the present application can provide: a straight-center motion mode in which the polishing plate rotates only about its own geometric axis (correspondingly, the mode switching mechanism is in a straight-center configuration); and an eccentric motion mode in which the polishing plate rotates about its own geometric axis while also revolving about another axis (correspondingly, the mode switching mechanism is in an eccentric configuration).

[0046] With specific reference to FIG1 , generally, the polishing machine includes a handle portion 12, a motor portion 14, and a transmission portion 16. The handle portion 12 is configured to be held by an operator's hand and includes a handle portion housing 22, a power switch (not shown) for the motor housed therein, and a trigger 18 extending from the interior of the handle portion housing 22 to the exterior for the operator to operate to control the power switch. The motor portion 14 includes a motor portion housing 24 and a motor housed therein (not shown). A motor shaft 15 (FIGS. 2 and 3) extending from the motor extends into the transmission portion 16, and a small bevel (or output) gear 11 (FIG. 3) disposed on the motor shaft 15 is disposed within the transmission portion 16. The transmission portion 16 includes a transmission portion housing 26 comprised of a top cover 32, an upper housing 34, and a lower housing 36. The top cover 32 of the transmission portion 16 can serve as an auxiliary operating portion. When the operator holds the handle portion 12 of the polishing machine with one hand while the tool is operating the workpiece, the other hand can press on it to help stabilize the polishing machine against the workpiece surface. Optionally, the transmission unit 16 may further include an auxiliary operating portion extending forward (opposite the handle unit 12) from the top cover 32 and / or upper housing 34. Thus, the handle unit 12 and the transmission unit 16 are connected to the rear and front of the motor unit 14, respectively, in the direction of extension of the motor shaft 15. The polishing machine's mode switching mechanism is disposed within the transmission housing 26 of the transmission unit 16, and the mode selection device 80 is mounted to the transmission housing 26 via fasteners 81, such as bolts.

[0047] 2, 3, and 4, the mode switching mechanism primarily includes a transmission shaft 25 and an output shaft 35 that are offset from one another, an inner ring gear 40 and a planetary carrier 50 that are coaxially arranged with the transmission shaft 25, planetary gears 60 that are coaxially arranged with the output shaft 35, and a balancing weight 70 disposed on the planetary carrier 50. This will be described in detail below.

[0048] The transmission shaft 25 has a central axis, also referred to herein as the first axis X1 ( FIG. 3 ), and is provided with a large bevel gear 21 fixed to the transmission shaft 25 so as to rotate synchronously therewith. The large bevel gear 21 is configured to mesh with the small bevel gear 11 provided on the motor shaft 15 so that when the motor shaft 15 rotates, the small bevel gear 11 on it drives the large bevel gear 21 and the transmission shaft 25 to rotate together. The transmission shaft 25 is rotatably supported within the transmission housing 26 of the transmission part 16 of the polishing machine by bearings 25a and 25b located on both sides of the large bevel gear 21. For example, as shown in FIG. 3 , the bearings 25a and 25b are supported in the top cover 32 and the upper housing 34, respectively. The transmission shaft 25 also includes a toothed section 28 having external teeth, or alternatively, the toothed section 28 can be replaced by a gear fixed to the transmission shaft 25 so as to rotate synchronously therewith when the transmission shaft 25 rotates.

[0049] Planetary gears 60, each with external teeth, are fixed to the output shaft 35 so as to rotate synchronously therewith. They mesh simultaneously with the external teeth of the toothed segment 28 of the transmission shaft 25 and the internal teeth of the ring gear 40. The ring gear 40 and planetary carrier 50 are rotatably supported on the transmission housing 26 of the transmission unit 16, specifically within the upper and lower housings 34 and 36, via bearings 40a and 50a, respectively (see Figures 2 and 3). The ring gear 40 and planetary carrier 50 are coaxially arranged with the transmission shaft 25 and are rotatable about the first axis X1 of the transmission shaft 25.

[0050] The output shaft 35 is rotatably supported in the shaft hole 55 of the planet carrier 50 via bearings 35a and 35b. The output shaft 35 has a central axis, also referred to as the second axis X2, offset in a first radial direction from the first axis X1, and is thus rotatable relative to the planet carrier 50 about the second axis X2. A polishing plate (not shown) of the polishing machine is fixedly mounted to the lower end of the output shaft 35, extending beyond the transmission housing 26, so as to be driven to rotate therewith (refer to FIG. 2 for the directional terms "upper" and "lower"). Thus, when the planetary gears 60 are driven to rotate by the toothed segment 28 of the transmission shaft 25 (serving as a sun gear), they drive the output shaft 35 to rotate with it, which in turn drives the polishing plate to operate on the workpiece.

[0051] 5 , the ring gear 40 includes an integrally formed body 42 and a base 44. The base 44 extends axially and radially outward from the body 42. The bearing 40a is mounted on the outer circumferential surface of the body 42 and is axially stopped by the base 44. The base 44 has an end surface 41 facing away from the body 42, and a plurality of circumferentially spaced projections 46 protrude axially from the end surface 41. As used herein, the terms "axial" or "axial direction" refer to the direction of the central axis of the component or along the first axis X1 or the second axis X2, and the terms "circumferential" or "circumferential direction" refer to directions around the "axial direction." Optionally, the ring gear 40 further includes a flange 48 extending axially away from the body 42 from the inner periphery of the base 44. In this case, the projections 46 may extend axially to the outer circumferential surface of the flange 48 (as shown) or not. The protrusions 46 may or may not extend radially to the outer circumference of the base 44 (as shown). Adjacent protrusions 46 define inner tooth gaps 49 therebetween. Each inner tooth gap 49 opens axially away from the base 44 and radially outward. The inner tooth gaps 49 are designed to receive a brake member (or a portion thereof) of the mode selector 80.

[0052] Each protrusion 46 has an inclined end surface 47 , and has a front edge 471 and a rear edge 473 along the rotation direction R1 of the ring gear 40 , wherein the distance between the front edge 471 and the end surface 41 is smaller than the distance between the rear edge 473 and the end surface 41 .

[0053] 6 , the planet carrier 50 includes a circular base plate 52, a first flange 54 and a second flange 56 extending axially oppositely from the base plate 52, and a shaft hole 55 for mounting the output shaft 35 extending axially through the base plate 52. The center axis of the shaft hole 55, i.e., the second axis X2, is offset from the first axis X1 in a first radial direction. A balancing weight 70 is fixed to the planet carrier 50, e.g., fastened to the base plate 52, and is located on the opposite side of the output shaft 35 relative to the first axis X1, i.e., offset in a second radial direction opposite to the first radial direction. Specifically, the center of mass of the total mass on one side of the balancing block 70 (the mass of all masses that revolve together on this side when the planetary carrier 50 revolves, including the mass of the balancing block and this side of the planetary carrier 50, etc.) and the center of mass of the total mass on one side of the output shaft 35 (the mass of all masses that revolve together on this side when the planetary carrier 50 revolves, including the planetary gear 60, the polishing base plate and related accessories not shown in the figure, the mass of this side of the planetary carrier 50, etc.) are located on opposite sides of the first axis X1. Preferably, the radial distance between the center of mass on one side of the balancing block 70 and the first axis X1 is as greater as possible than the radial distance between the center of mass on one side of the output shaft and the first axis X1, so as to minimize the mass of the balancing block 70.

[0054] The balancing weight 70 can be configured as a single unit. More preferably, to maximize spatial angle utilization, the balancing weight 70 includes first and second balancing weights 72 and 74 fixed to opposing surfaces 51 and 53 ( FIG. 4 ) of the base plate 52. The balancing weight 70 is composed of the first and second balancing weights 72 and 74, respectively, located on opposing sides of the base plate 52, and the center of mass of the balancing weight 70 is positioned as close to the base plate 52 as possible. Most preferably, the center of mass of the total mass on one side of the balancing weight 70 and the center of mass of the total mass on one side of the output shaft 35 are located in the same plane perpendicular to the first axis X1 (or second axis X2) to avoid generating unnecessary torque that could disrupt the dynamic balancing effect.

[0055] A planet carrier gap 59 is formed on the end surface 57 of the first flange 54 that faces the ring gear 40. There can be only one planet carrier gap 59. Alternatively, as shown, two planet carrier gaps 59 can be arranged diametrically opposed to each other. The planet carrier gap 59 is open in the axial direction away from the first flange 54 and can be open outward in the radial direction. Similar to the ring gear gap 49, the planet carrier gap 59 is also designed to receive a portion of the brake member of the mode selection device 80. Between the two planet carrier gaps 59, the end surface 57 is inclined. In the rotation direction R2 of the planet carrier 50 (opposite to the rotation direction R1 of the ring gear 40), the end surface 57 is axially inclined toward the base plate 52, that is, the axial length of the first flange 54 extending from the base plate 52 is reduced. As is also clearly seen in FIG6 , the surface 51 of the base plate 52 of the planet carrier 50 includes bosses 62 and 64, each formed with fastener holes 61 and 63. Fasteners 66 and 68 extend through corresponding holes 71 and 73 ( FIG2 ) formed in the balancing weight 72 and fastener holes 61 and 63, respectively, to secure the balancing weight 72 to the base plate 52 of the planet carrier 50. Bosses 62 and 64 may, but are not necessarily, connected by a connection 65. Of course, bosses 62 and 64 may be configured as a single, oblong boss. FIG2 also shows fasteners 66 and 68 for securing the balancing weight 74 to the planet carrier 50. It is contemplated that a similar structure could be used to secure the balancing weight 74 to the other surface 53 of the base plate 52 of the planet carrier 50. Any mechanical structure known in the art (e.g., welding, snap-fitting, form-fitting, etc.) capable of securing the balancing weights 72 and 74 to the base plate 52 of the planet carrier 50 could be used in place of the illustrated structure.

[0056] 7 to 9 , the mode selection device 80 of the polishing machine will be described. The mode selection device 80 mainly includes a selection housing 82 , an operating member 84 , a biasing spring 86 and a braking member 88 .

[0057] The selector housing 82 may include, for example, a disc-shaped base 822 (FIGS. 1 and 9), a protrusion 824 integrally formed from one side of the base 822, and a generally annular portion 826 extending from the other side of the base 822. Fasteners 81 (FIG. 1) pass through through-holes 85 (FIGS. 1, 8, and 9) formed through the selector housing 82 and into corresponding holes 27 (FIG. 7) formed in the transmission housing 26 to secure the selector housing 82 to the transmission housing 26 of the transmission 16. The protrusion 824 may have any shape and size suitable for an operator's hand to operate and rotate the selector housing 82. The cylindrical outer circumferential surface 821 of the generally annular portion 826 is configured to engage the cylindrical inner circumferential surface 13 (see FIG. 7) of the annular portion 17 formed on the transmission housing 26 of the transmission 16, enabling the selector housing 82 to rotate relative to the annular portion 17 of the transmission housing 26.

[0058] The operating member 84 is configured to be mounted to the selector housing 82 and includes an operating portion 842 that protrudes from the selector housing 82 so as to be operable by an operator. A biasing spring 86 is mounted in an opening 825 formed in a protrusion 824 of the selector housing 82, with one end abutting the selector housing 82 and the other end being received in a cavity 843 ( FIG. 9 ) defined by the operating portion 842 to apply a biasing force to the operating portion 842. The operating member 84 also includes a neck portion 844 extending from the operating portion 842 and spanning the generally annular portion 826 of the selector housing 82, and an extension portion 846 extending from the neck portion 844 and having a housing engaging portion 845 and an engagement end 847. The housing engaging portion 845 is configured to engage with an opening 19 (oppositely disposed upper and lower openings 19 a and 19 b are illustrated in FIG. 7 ) formed in the annular portion 17 of the transmission housing 26, and the engagement end 847 is configured to engage and actuate the brake member 88.

[0059] The brake member 88 includes a generally annular body 882 and a protruding piece 884 protruding from the annular body, wherein the protruding piece 884 is configured to selectively engage with the planet carrier gap 59 of the planet carrier 50 or the inner ring gear gap 49 of the inner ring gear 40. The generally annular body 882 includes two opposing arc-shaped portions 881 and two opposing straight portions 883 connecting the two arc-shaped portions 881.

[0060] Thus, when the operating member 84 is not actuated (pressed) by the operator, the operating member 84 is held in the initial position shown in FIG9 by the biasing force of the biasing spring 86. At this time, the neck portion 844 of the operating member 84 engages with the annular portion 826 of the selection housing 82, the housing engaging portion 845 of the operating member 84 engages with or extends into the opening 19 (e.g., the upper opening 19a) formed on the annular portion 17, and the engaging end 847 engages with one of the straight portions 883 (shown as the one away from the protruding piece 884) of the substantially annular body 882 of the brake member 88 and pushes the straight portion 883 in the direction of the biasing force of the biasing spring 86, so that the protruding piece 884 of the brake member 88 engages with the inner gear gap 49 of the inner gear ring 40, as shown in FIG10.

[0061] At this point, the mode switching mechanism is in an eccentric configuration, and the polishing machine is in eccentric motion mode, with the ring gear 40 locked by the tab 884 of the mode selector's brake 88 and unable to rotate about the first axis X1. In this mode, the rotation of the motor shaft 15 drives the transmission shaft 25 via the meshing of the bevel pinion 11 and the bevel gear 21. With the ring gear prohibited from rotating, the toothed segment 28 of the transmission shaft 25 (equivalent to the sun gear) drives the meshing planetary gears 60 and the output shaft 35 to rotate about their own rotational axis X2. Simultaneously, the planetary carrier 50, along with the first and second balancing masses 72 and 74 mounted thereon, rotates about the first axis X1. Consequently, the polishing base plate (not shown) mounted to the output shaft 35 performs an orbital operation on the workpiece, rotating about the second axis X2 and orbiting about the first axis X1.

[0062] At this point, the operator's finger presses (downward in the illustrated embodiment) the operating portion 842 of the operating member 84 against the biasing force of the biasing spring 86, causing the neck portion 844 of the operating member 84 to disengage from the generally annular portion 826 of the selector housing 82. Simultaneously, the housing engaging portion 845 of the operating member 84 moves (downward) away from the opening 19a of the annular portion 17 and into the interior of the inner circumferential surface 13 of the annular portion 17, abutting against or spaced apart from it. The engaging end 847 no longer pushes against the straight portion 883 of the generally annular body 882 of the actuator 88. At this point, the selector housing 82 can be rotated relative to the transmission housing 26.

[0063] Next, the operator's hand rotates the protrusion 824 of the selection shell 82, and the shell engaging portion 845 of the operating member 84 pushes against or roughly pushes against the inner circumferential surface 13 of the annular portion 17 to rotate (once the operating member 84 is rotated to the point where the shell engaging portion 845 is no longer aligned with the opening 19a, the finger pressing the operating portion 842 can be released), and at the same time, the engaging end 847 moves along one of the arc-shaped portions 881 of the roughly annular body 882 of the brake member 88. When the housing engaging portion 845 of the operating member 84 reaches the lower opening 19b on the annular portion 17 (rotated approximately 180 degrees), the biasing force of the biasing spring 86 pushes the operating member 84 outward (downward), and the housing engaging portion 845 of the operating member 84 enters the lower opening 19b. At the same time, the engaging end 847 of the operating member 84 pushes against the other straight portion 883 (the one close to the protrusion 884) of the approximately annular body 882 of the brake member 88, thereby moving the brake member 88 downward and finally causing the protrusion 884 to enter the planetary carrier gap 59 of the planetary carrier 50, as shown in Figure 11.

[0064] At this point, the mode switching mechanism is in the straight-center configuration, and the polishing machine is in the straight-center motion mode. Because the tabs 884 of the brake member 88 engage within the planetary carrier gap 59, the planetary carrier 50 is prevented from rotating about the first axis X1 and remains stationary along with the first and second balance weights 72 and 74 secured thereto. Meanwhile, the ring gear 40 is permitted to rotate about the first axis X1. In this mode, driven by the motor, the transmission shaft 25 rotates, and the toothed segments 28 drive the planetary gears 60 to rotate about their own rotational axes X2, while the ring gear 40 simultaneously rotates about the first axis X1. Due to the rotation of the ring gear 40, the planetary gears 60 and the output shaft 35 rotate only about the second axis X2, not about the first axis X1 (revolution).

[0065] As described above, when the polishing machine switches between the eccentric motion mode and the straight-center motion mode, the operator only needs to operate (press and rotate) the operating member 84 of the mode selection device 80, while the various moving components of the mode switching mechanism housed in the transmission portion 16 do not move, particularly the relatively large balancing weight 70 (assembly). This helps maintain the coordination and motion accuracy of the various components of the mode switching mechanism, ensuring the dynamic balance of the polishing machine in both motion modes and extending the service life of the polishing machine. The balancing weight 70 (assembly) of the polishing machine only moves and rotates when the polishing machine is in the eccentric motion mode and remains stationary when the polishing machine is in the straight-center motion mode, which also helps improve the coordination and motion accuracy described above.

[0066] When the polishing machine switches from the eccentric motion mode to the straight-center motion mode, the operator can rotate the selection housing 82 in any direction, which can be clockwise or counterclockwise.

[0067] When the polishing machine switches from a centric motion mode in which the ring gear 40 rotates about the first axis X1 but the planet carrier 50 does not rotate about the first axis X1 to an eccentric motion mode in which the ring gear 40 does not rotate about the first axis X1 but the planet carrier 50 rotates about the first axis X1, there is a possibility that the ring gear 40 is still rotating when the protruding piece 884 of the brake member 88 moves out of the planet carrier gap 59 of the planet carrier 50 and is about to enter the ring gear gap 49 of the ring gear 40. To prevent the protruding piece 884 of the brake member 88 from suddenly entering the ring gear gap 49 of the rotating ring gear 40 and causing damage to the protruding piece 884 of the brake member 88 and / or the ring gear gap 49 of the ring gear 40, as described above and shown in FIG. 5 , the inclined end surface 47 of the protrusion 46 between adjacent ring gear gaps 49 has a front edge 471 lower than a rear edge 473 in the rotation direction R1 of the ring gear 40. This arrangement prevents the protruding piece 884 of the brake member 88 from entering any of the inner gear gaps 49 when the rotational speed of the inner gear ring 40 exceeds a predetermined speed. Specifically, when the protruding piece 884 of the brake member 88 initially engages the end surface 47 of a particular protrusion 46, as the inner gear ring 40 moves (rotates) in the rotational direction R1, the end surface 47 axially pushes the protruding piece 884 of the brake member 88 further away from the inner gear gap 49, causing the protruding piece 884 of the brake member 88 to pass over the end surface 47 of the protrusion 46, thereby reducing the rotational speed of the inner gear ring 40 to a certain extent. Similarly, the protruding piece 884 of the brake member 88 successively passes over the protrusion 46 following the protrusion 46 until the rotational speed of the inner gear ring 40 falls below the predetermined speed. At this time, the resistance of the inclined end surface 47 to the protrusion 884 of the brake member 88 is less than the elastic force of the biasing spring 86, and the protrusion 884 of the brake member 88 can enter the next inner gear gap 49, causing the inner gear 40 to stop rotating.

[0068] Similarly, when the polishing machine is in eccentric motion mode, the planet carrier 50 and the counterweight 70 rotate together about the first axis X1. Therefore, when switching from eccentric motion mode to centric motion mode, the planet carrier 50 may still be rotating. To prevent damage to either of the planet carrier 50 due to sudden engagement of the protrusions 884 of the brake member 88 with the carrier gaps 59, as described above and shown in FIG6 , the end surface 57 of the planet carrier 50 located between the two carrier gaps 59 is also inclined. Using the same principle as the ring gear 40, the inclined end surface 57 prevents the protrusions 884 of the brake member 88 from entering the carrier gaps 59 when the rotational speed of the planet carrier 50 exceeds a predetermined speed, while simultaneously reducing the rotational speed of the planet carrier 50. Once the rotational speed of the planet carrier 50 decreases to the predetermined speed, the protrusions 884 of the brake member 88 are prevented from entering the carrier gaps 59. Thereafter, rotation of the planet carrier 50 is stopped, and the polishing machine enters centric motion mode.

[0069] As shown in FIG1 , the mode selector 80 is mounted on one side of the polishing machine (relative to the axis of the motor shaft 15). In this case, the diameter defined by the two planetary carrier gaps 59 of the planetary carrier 50 is preferably perpendicular or approximately perpendicular to the plane defined by the first axis X1 and the second axis X2. Thus, when the tab 884 of the brake member 88 of the mode selector 80 enters or engages any of the planetary carrier gaps 59, the second axis X2 on which the output shaft 35 is located is located within a vertical plane on the axis of the motor shaft 15, for example, approximately directly below the axis. The second axis X2 can be located either in front of or behind the transmission portion 16 in the direction of extension of the motor shaft axis. The second axis X2 being within the vertical plane on the axis of the motor shaft helps the operator maintain better balance while holding the handle 12 of the polishing machine.

[0070] As described above, the polishing machine of the present application can provide: a linear motion mode in which the polishing base plate rotates about its own central axis on the workpiece surface, and an eccentric motion mode in which the polishing base plate not only rotates about its own central axis but also revolves about another axis parallel to but offset from the central axis. Thus, when operating in the linear motion mode, the polishing machine of the present application can perform a paint repair process and repair deep paint scratches, and the balancing weight does not function in this mode. When operating in the eccentric motion mode, the polishing machine can effectively remove light streaks and sun streaks, achieving a fine polish on the paint surface and making the paint surface more shiny. In this mode, the balancing weight balances the movement of the output shaft and reduces vibration caused by the eccentric motion. Furthermore, when the polishing machine switches between the linear motion mode and the eccentric motion mode, the moving parts of the mode switching mechanism of the polishing machine do not move at all. This ensures the accuracy and coordination of the transmission components, ensures that the dynamic balancing effect in either mode is not compromised, and makes the polishing machine more durable.

[0071] The principles of the present application have been described in detail above with reference to the accompanying drawings. However, those skilled in the art will appreciate that the embodiments shown in the drawings and described above are exemplary and are not intended to limit the scope of protection of the present invention. Various modifications, adaptations, and combinations of the features of the described embodiments may be made without departing from the scope of protection defined in the claims.

Claims

1. A mode switching mechanism for a power tool having an eccentric configuration and a straight-center configuration and comprising: a transmission shaft (25) comprising a toothed section (28) having external teeth and configured to rotate about its first axis (X1) when driven by the motor of the power tool; an inner gear ring (40) coaxially arranged with the transmission shaft (25); a planet carrier (50) coaxially arranged with the transmission shaft (25); an output shaft (35) mounted to the planet carrier (50) and rotatable relative to the planet carrier (50) about its own second axis (X2), the second axis (X2) being parallel to the first axis (X1) and arranged in a first radial direction therefrom; a balancing mass (70) fixed to the planet carrier (50), the center of mass of the balancing mass (70) being offset from the first axis (X1) in a second radial direction opposite to the first radial direction; and a planetary gear (60) which is coaxial with the output shaft (35) and relatively fixedly mounted thereon and meshes with both the toothed segment (28) and the inner gear ring (40); In the eccentric configuration, the inner ring gear (40) is engaged by the braking member of the mode selection device of the power tool and is prohibited from rotating around the first axis (X1), so that the planetary gear and the output shaft rotate around the second axis while rotating around the first axis together with the planetary carrier and the balance block. In the straight-center configuration, the planetary carrier (50) is engaged by the braking member and is prohibited from rotating around the first axis (X1), so that the planetary gear and the output shaft rotate only around the second axis.

2. The mode switching mechanism for an electric tool according to claim 1, wherein: The inner ring gear (40) and the planet carrier (50) respectively include an inner ring gear gap (49) and a planet carrier gap (59) configured to receive at least a portion of the brake member.

3. The mode switching mechanism for an electric tool according to claim 2, wherein: The inner gear ring (40) has an end surface (41) and a plurality of protrusions (46) protruding from the end surface and arranged at intervals in the circumferential direction, and the inner gear ring gaps (49) are defined between adjacent protrusions (46).

4. The mode switching mechanism for an electric tool according to claim 2, wherein: The planet carrier (50) includes a base plate (52) and a first flange (54) and a second flange (56) extending in opposite directions from the base plate (52) in the axial direction, and the planet carrier gap (59) is formed on an end surface of the first flange (54).

5. The mode switching mechanism for an electric tool according to claim 4, wherein: Two planet carrier gaps (59) arranged opposite to each other in the diameter direction are formed on the end surface of the first flange (54).

6. The mode switching mechanism for an electric power tool according to claim 5, wherein: The diameter direction defined by the two planet carrier gaps (59) is perpendicular to a plane defined by the first axis and the second axis.

7. A mode switching mechanism for an electric tool according to any one of claims 4 to 6, wherein: The balancing weight includes a first balancing weight (72) and a second balancing weight (74) respectively fixed to two surfaces of the base plate (52) opposite to each other in the axial direction.

8. The mode switching mechanism for an electric tool according to any one of claims 1 to 6, wherein: The center of mass of the side of the planetary carrier (50) where the balancing block is located and the center of mass of the side of the planetary carrier (50) where the output shaft is located are located in the same plane perpendicular to the first axis (X1).

9. An electric tool having a straight-center motion mode and an eccentric motion mode, and comprising: Transmission housing (26); A mode switching mechanism according to any one of claims 1 to 8, which is accommodated in a transmission housing (26), and an output shaft (35) of the mode switching mechanism extends out from the transmission housing (26); and A mode selection device (80) mounted on a transmission housing (26), the mode selection device (80) comprising: a selection housing (82) configured to be rotatably mounted on the transmission housing (26); The brake member (88), and at least a portion of the brake member is configured to selectively engage with one of the ring gear and the planet carrier of the mode switching mechanism; and An operating member (84) is mounted on the selection housing (82) and is configured to be operated by an operator, the operating member comprising a housing engagement portion (845) and an engagement end (847) configured to engage with the brake member (88), the operating member (84) being configured to: In the first position not operated by the operator, the housing engagement portion (845) engages the transmission housing (26) to prevent the selection housing (82) from rotating relative to the transmission housing, and the engagement end (847) engages the brake member (88) to prevent the selection housing (82) from rotating relative to the transmission housing. It is in a state where the at least one portion is engaged with one of the inner ring gear and the planet carrier, and In the second position operated by the operator, the housing engagement portion (845) is disengaged from the transmission housing (26) to allow the selection housing and the transmission housing to rotate, and the engagement end (847) is disengaged from the brake (88).

10. The electric tool according to claim 9, wherein: In the second position of the operating member (84), the braking member (88) is still in a state where the at least one portion is engaged with one of the inner ring gear and the planet carrier.

11. The electric tool according to claim 9, wherein: The brake member (88) includes a body (882) and a protrusion (884) extending from the body (882), wherein the protrusion is the at least one portion.

12. The electric tool according to claim 11, wherein: The main body (882) includes a relative annular portion (881) and two relative straight portions (883) connecting the relative annular portions. In the first position of the operating member (84), the engaging end (847) contacts and pushes against one of the two relative straight portions (883). In the second position of the operating member (84), the engaging end (847) does not contact either of the two relative straight portions (883).

13. The electric power tool according to claim 9, wherein: The selection housing (82) includes a base (822), a protrusion (824) extending from a first side of the base (822) and suitable for being rotated by an operator, and an annular portion (826) extending from an opposite second side of the base (822), and the operating member (84) includes an operating portion (842) extending from the protrusion (824) to be operated by an operator between a first position and a second position.

14. The electric tool according to any one of claims 9 to 13, wherein: The transmission housing (26) includes an annular portion, which includes two cutouts (19) arranged opposite to each other in a diameter direction and configured to receive the housing engagement portion (845), wherein in the first position of the operating member (84), the housing engagement portion (845) engages one of the two cutouts, and in the second position of the operating member (84), the housing engagement portion (845) does not engage either of the two cutouts.

15. The electric tool according to any one of claims 9 to 13, wherein: The electric tool is an electric polishing tool.

16. The electric tool according to claim 15, wherein: It also includes a motor, the rotation axis of the motor shaft (15) of the motor is perpendicular to the first axis and the second axis, and the mode selection device (80) is arranged on either side of the transmission housing (26) relative to the rotation axis.

Images