TECHNICAL FIELD
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The present invention relates to an impact tool, in particular an impact drive comprising an anvil for attaching a front-end tool.
BACKGROUND ART
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Impact Drivers usually have chuck that has 1/4lnch Hex or a 7/16 Inch Hex opening for inserts. Especially adapters that are used for bolting application, but basically all inserts can break inside the chuck. Usually, this break happens in a way that the insert can still be removed. Sometimes the break happens in a way that only a small part remains behind the locking balls. It is nearly impossible to remove this part and as the chuck is part of the anvil, either the anvil or the whole gearbox has to be scrapped.
SUMMARY OF THE INVENTION
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An objective of the present invention is to provide an impact driver that can be repaired more conveniently at a lower cost when a front-end tool breaks and becomes jammed in the anvil.
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An impact driver, comprising a housing, a motor, a main shaft and an impact mechanism, the impact mechanism comprising an anvil and a hammer which is both rotationally and axially movable relative to the anvil, a rotational driving force of the motor being transmitted to the main shaft and converted by means of the hammer to a rotational striking force, the anvil receiving the rotational striking force of the hammer and thus rotating about a rotation axis A, a front end of the anvil being provided with a chuck portion for receiving a front-end tool, the chuck portion being provided with an axially extending insertion hole, and a rear end of the anvil being provided with a receiving opening for receiving a front end of the main shaft, wherein the insertion hole and the receiving opening are connected to each other. Thus, if the front-end tool breaks and a broken part is jammed in the insertion hole, the housing of the impact driver can be opened, and the remaining part of the broken front-end tool that is jammed in the insertion hole can be pushed out of the anvil using a maintenance tool, so that there is no need to scrap the entire anvil; thus, the convenience of maintenance is increased while the cost of maintenance is greatly reduced.
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According to an embodiment of the present invention, the insertion hole and the receiving opening are connected by a connecting hole extending axially along the rotation axis A. Thus, after removing the anvil from the housing, the remaining part of the broken front-end tool can be removed by merely inserting a maintenance tool in the form of a thin rod into the connecting hole, and pushing the remaining part out of the insertion hole; the anvil can then be re-fitted in the housing for further use, greatly reducing maintenance costs.
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Preferably, the connecting hole, the insertion hole and the receiving opening are coaxial. Thus, the maintenance tool in the form of a thin rod inserted into the connecting hole can abut the centre of the broken part remaining in the insertion hole, to push it out more easily.
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The connecting hole has a diameter smaller than that of the insertion hole and/or the receiving opening. The strength of the anvil can be ensured when the connecting hole has a smaller diameter; otherwise, the anvil acting as an output shaft might be at risk of breaking during application due to a hole wall being too thin.
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According to another embodiment of the present invention, the receiving opening is provided with a sealing gasket at an end connected to the connecting hole. The sealing element can prevent unnecessary, excessive leakage of grease between the gearbox and the chuck.
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According to another embodiment of the present invention, a sealing element is provided in the connecting hole, the sealing element being held in the connecting hole when not subjected to an axial pushing force, and being able to move axially in the connecting hole when subjected to an axial pushing force.
BRIEF DESCRIPTION OF THE DRAWINGS
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A better understanding of the embodiments mentioned can be gained from the following detailed description with reference to the drawings. It is emphasized that various components are not necessarily drawn to scale. In fact, dimensions may be increased or decreased at will for the purpose of clear description. In the drawings, identical reference signs denote identical elements.
- Fig. 1 is a complete sectional view of an impact driver in an embodiment of the present invention.
- Fig. 2 is a partial enlarged sectional view of the impact driver shown in Fig. 1.
- Fig. 3 is a schematic drawing of an anvil of an impact driver in an embodiment of the present invention.
- Fig. 4 is a sectional view of the anvil shown in Fig. 3.
- Fig. 5 is a partial enlarged sectional view of the impact driver in the other embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
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The impact driver of the present invention is described below with reference to Figs. 1 - 5. The following description is merely exemplary, and does not limit the disclosed content of the present application or the applications or uses of the present invention. In the description of the present invention, it should be understood that orientations or positional relationships indicated by terms such as "centre", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "inside", "outside", "axial", "radial" and "circumferential" are based on orientations or positional relationships shown in the drawings, and are only for facilitating the description of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be construed as limiting the present invention.
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Fig. 1 shows an exemplary impact driver 1. The impact driver 1 has: a main body part 2; a handle 3, protruding downwards from the main body part 2; and a battery fitting part 4 arranged at a lower end of the handle 3, with a battery pack (not shown) fitted to the battery fitting part 4. As shown in Fig. 1, the main body part 2 comprises a housing 20, with the following arranged in the housing 20: a motor 21, a planetary gear mechanism 22, a main shaft 23, a spring 24, a hammer 25 and an anvil 10. In this embodiment, a direction parallel to a rotation axis A of the anvil 10 is suitably called the axial direction. In this embodiment, the rotation axis A extends in a front-rear direction. The axial direction coincides with the front-rear direction. A rotation axis of the motor 21, a rotation axis of the main shaft 23 and the rotation axis A of the anvil 10 coincide with each other. The motor 21 is the source of driving power for the impact driver 1. A rotational driving force of the motor 21 is reduced in speed by the planetary gear mechanism 22, and transmitted to the main shaft 23. The rotational driving force transmitted to the main shaft 23 is converted to a rotational striking force by the hammer 25. The anvil 10 can come into contact with the hammer 25 in the direction of rotation. The rotational striking force of the hammer 25 is transmitted to the anvil 10. The anvil 10 receives the rotational striking force and rotates about the rotation axis A.
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The anvil 10 is deployed at a position in front of the hammer 25. The anvil 10 is supported on the housing 20 in such a way as to be radially non-displaceable. An anvil bearing 26 is installed in the housing 20. The anvil 10 is supported by the anvil bearing 26 so as to be capable of rotating about the rotation axis A. In addition, the impact driver 1 further comprises a tool holding means 5 for holding a front-end tool, the tool holding means being arranged at a periphery of a front end of the anvil 10.
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Referring to Figs. 2- 4, a pair of extension parts 11 extending radially is provided at a rear end of the anvil 10, and a receiving opening 12 is formed at the centre of the two extension parts at the rear end of the anvil 10. A front end of the main shaft 23 is inserted in the receiving opening 12. A chuck portion 13 for receiving a front-end tool 6 is provided at the front end of the anvil 10. The chuck portion 13 comprises an insertion hole 14 for insertion of the front-end tool. The front-end tool 6 comprises various well-known drill bits, drill bit holders, or adapters for bolt fastening, etc. The front-end tool (not shown) often has a hexagonal tail end, which is inserted in the insertion hole 14 which is likewise hexagonal, and then locked in the insertion hole 14 by a locking ball of the tool holding means 5. During operation of the impact driver 1, a rotational impact force received by the anvil 10 is transmitted onwards by the anvil to the front-end tool 6 to perform an application task.
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According to an embodiment of the present invention, as shown in Fig. 4, the insertion hole 14 and the receiving opening 12 are connected to each other. Thus, if the front-end tool breaks and a broken part is jammed at a rear side of the insertion hole 13 by the locking ball of the tool holding means 5, the housing 20 of the impact driver can be opened to remove the anvil 10 from the housing 20, and the remaining part of the broken front-end tool that is jammed in the insertion hole 14 can then be pushed out of the insertion hole 14 using a maintenance tool, so that there is no need to scrap the entire anvil; thus, the convenience of maintenance is increased while the cost of maintenance is reduced. Furthermore, since the insertion hole 14 and the receiving opening 12 are connected to each other, there will be no compression of gas in the receiving opening 12 by the front end of the main shaft 23, causing resistance to installation, when the front end of the main shaft 23 is accommodated in the receiving opening during assembly of the impact driver. During operation of the impact driver, high-speed rotation of the main shaft 23 and the hammer 25 might also cause the temperature of gas in the housing 20 to rise, such that lubricating oil in the housing is at risk of being vaporized by high-temperature gas and consequently leaking. When the insertion hole 14 and the receiving opening 12 are connected to each other, gas pressures inside and outside the housing can be balanced, thereby avoiding undesired leakage of lubricating oil.
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Referring to Fig. 4, the insertion hole 14 and the receiving opening 12 are connected to each other by a connecting hole 15 extending in the axial direction of the rotation axis A. That is to say, an axially extending connecting hole 15 is provided between a rear end of the insertion hole 14 and a front end (the end facing the front-end tool) of the receiving opening 12. Thus, if the front-end tool breaks and there is a broken part, the part of the broken front-end tool that is jammed in the insertion hole can be pushed out of the anvil by opening the gearbox and using a maintenance tool to insert a thin rod into the connecting hole, so that there is no need to scrap the entire anvil or even the gearbox; thus, the convenience of maintenance is increased while the cost of maintenance is greatly reduced.
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The connecting hole 15, the insertion hole 14 and the receiving opening 12 are coaxial. Thus, the thin rod inserted into the connecting hole 15 can abut the centre of the broken part remaining in the insertion hole 14, to push it out more easily. The connecting hole 15 has a diameter smaller than that of the insertion hole 14 and the receiving opening 12. The strength of the anvil 10 can be ensured when the connecting hole 15 has a smaller diameter; otherwise, the anvil 10 acting as an output shaft might be at risk of breaking during an application task due to a hole wall being too thin.
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It will be understood that the shape of a cross section of the connecting hole 15 perpendicular to the rotation axis A is not limited to a round hole, and could also be square, hexagonal or an irregular shape. Furthermore, dimensions of the cross section of the connecting hole 15 perpendicular to the rotation axis A could also be variable, for example, gradually decrease from a side adjacent to the receiving opening 12 to a side adjacent to the insertion hole, or be step-shaped. Of course, it is also possible for the connecting hole 15 to taper towards the centre from two ends adjacent to the receiving opening 12 and the insertion hole 14.
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According to a preferred embodiment of the present invention, referring to Fig. 2, the receiving opening 12 is provided with a sealing element 16 at an end connected to the connecting hole 15. The sealing element 16 may be felt or a sealing gasket, to prevent unnecessary, excessive leakage of grease between the gearbox and the chuck portion 13. Alternatively, as shown in Fig. 5 the sealing element 16 is arranged in the connecting hole 15; the sealing element 16 is held in the connecting hole 15 when not subjected to an axial pushing force, and is able to move axially in the connecting hole 15 when subjected to an axial pushing force.
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As stated above, although exemplary embodiments of the present invention have been explained herein with reference to the drawings, the present invention is not limited to the specific embodiments above, and could have many other embodiments. The scope of the present invention shall be defined by the claims and their equivalent meaning.