Electric tool

An electric tool includes a gripping portion, a working portion rotatably connected to the gripping portion about an axis, an output shaft moving in a reciprocating manner and accommodated in the working portion, and a gear box accommodated in the gripping portion for driving the output shaft. The gear box has an opening so that the output shaft is moveable from one end to the other end of the opening when the working portion is rotated relative to the gripping portion about the axis. A leakage-preventing device, such as a bushing, is arranged at the opening so that the lubricating grease can be avoided from leaking.

RELATED APPLICATION DATA

This application claims the benefit of CN 201010253482.3, filed on Aug. 8, 2010, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The subject disclosure generally relates electric tools and, more particularly, to a leakage-preventing and sealing device for the grease lubricating the moveable members inside an electric tool.

In electric tools, most of the moveable members need to be lubricated by grease. The lubricating effect of the grease is, however, often diminished with use of the electric tool. This is particularly true for electric tools having high-speed-rotating moveable members. Moreover, if the grease leaks out to an electrical connection part, the electric connection quality could be affected.

SUMMARY

To solve the above-mentioned problems, the following describes an electric tool equipped with a leakage-preventing device.

More particularly, described hereinafter is an electric tool having a gripping portion, a working portion rotatably connected to the gripping portion about an axis, a gear box accommodated within the gripping portion and having an opening, and an output shaft movably accommodated within the working portion in a reciprocating manner with the output shaft being rotated and displaced from one end to the other end of the opening along with the working portion. A leakage-preventing device is arranged at the opening.

In a described embodiment, the leakage-preventing device comprises a bushing rotatably arranged within the gear box, and the bushing is provided with a hole through which the output shaft may pass. Generally, the hole extends along the axis direction of the output shaft.

Further, the bushing may be provided with a notch and a grease-gathering portion, shaped as a barb, may be arranged at a first end or/and a second end of the notch where it protrudes to the inside of the bushing.

Still further, a transmission gear may be contained in the gear box and the transmission gear is provided with a groove within which the first end and/or the second end of the notch can be engaged.

Yet further, impact components may also be contained in the gear box and an isolating rib portion, for avoiding grease leaking, may be arranged between the transmission gear and the impact components.

Yet further, the working portion may be provided with a light source with a scraping device being arranged on an electric connection device of the light source.

Yet further, the electric connection device may comprise a moveable connecting piece arranged on the working portion and a stationary connecting piece connected with the moveable connecting piece and disposed on the gripping portion with the scraping device having scraping pieces disposed on the two sides of the moveable connecting piece respectively and with one end of a scraping piece contacting with the stationary connecting piece.

Yet further, the scraping device may include grease-gathering grooves disposed on two ends of the stationary connecting piece.

By adopting one or more of the above mentioned technical solutions, the following technical effects can be obtained:

1) with the bushing disposed at the opening of the gear box for avoiding grease leaking, the opening of the gear box can be covered no matter how the bushing is displaced along with the output shaft, so that leaking of the lubricating grease can be avoided;

2) the isolating rib portion disposed between the transmission gear and the impact components can decrease the flowing diffusion of the lubricating grease from the transmission area to the striking area; and

3) if the connecting piece of the light source is adhered with the leaked lubricating grease, the scraping piece can scrape away the leaked lubricating grease to ensure the unobstructed contact between the connecting pieces and the grease-gathering grooves disposed on the ends of the scraping piece respectively along the rotation direction thereof can be used for gathering the scraped grease.

DETAIL DESCRIPTION

A preferred embodiment of an electric tool will be explained in detail hereinafter wherein the electric tool is embodied in an electric hammer for striking a nail. It is to be understood, however, that this illustrative embodiment is not intended to be limiting. Rather, those of skill in the art will readily understand how to utilize the various components described hereinafter in other electrical devices to achieve the same results.

As shown inFIGS. 1-6, an electric hammer comprises a gripping portion20having a first axis A and a working portion10having a second axis B, the working portion10being rotatable with respect to the gripping portion20about a third axis C which is perpendicular to a plane defined by the first axis A and the second axis B. The intersection between the second axis B and the first axis A is closer to the tip end of the gripping portion20than the intersection between the third axis C and the first axis A, so that the working portion10can be operated in a narrower space.

As shown inFIG. 1, when the electric hammer is operated at a corner area formed by two workpieces that are disposed perpendicular to each other, the nail is struck into one workpiece at an angle of 45 degrees relative to the surface of the other workpiece so as to connect the two workpieces. In this case, the working portion10is rotated by 135 degrees relative to the gripping portion20and the hand of the operator grips the upright gripping portion, so that it is labor-saving and comfortable for operation. To enhance the light brightness in the working area50during striking of a nail, a light source30may be further disposed on the rotatable working portion10. As shown inFIG. 2, when one workpiece at the top needs to be operated upon, it is unnecessary for the operator to adjust the orientation of the gripping portion20manually but, instead, the operator need only rotate the working portion10to a position that is 180 degrees relative to the gripping portion20, so that the operation of the device remains convenient.

As shown inFIGS. 3-6, the working portion10has positioned therein working parts1which mainly comprises an output shaft7for striking a nail, a bushing6exteriorly mounted on the output shaft7, a cover12and a nail-receiving opening11, etc. The gripping portion20comprises a housing2for supporting a gear box5and the working parts1. A transmission gear9and impact components8are supported within the gear box5. A releasing button3is further provided on the housing2for locking and releasing the working parts1, which can be restored by a biasing member4.

The operation principle of rotation is that: the releasing button3has a discontinuous surface on the periphery thereof, accordingly, the housing2and the working parts1also have discontinuous surfaces for mating with that of the releasing button3. When the releasing button3is located between the housing2and the working parts1, the working parts1are locked and can not be rotated. When the releasing button3is pressed, the discontinuous surface of the releasing button3disengages from the housing2and entirely enters into the working parts1, so that the working parts1can be rotated. Due to the biasing member4, the releasing button3has a tendency of disengaging from the working parts1and entering into the housing2. When the releasing button3is rotated by a certain angle, the discontinuous surface thereof is consistent with the discontinuous surface on the housing2, as a result, the releasing button3enters into the housing and the working parts1is locked.

When the working parts1rotate, the output shaft7mounted thereon is substantially tangential at its axle center to the peripheral circle of the rotating impact components8.

As shown inFIGS. 4 and 7, the connection mode of the light source30(preferably, a LED light) is schematically shown. For the convenience of the user after rotating the working parts1, the LED light is configured to be rotated along with the working parts1. The LED is mounted on the working parts1so that the light emitted therefrom can illuminate the working area50in front of the nail-receiving opening11. The wiring takes the form of: the positive and negative wires are led out from the LED at one end thereof and soldered onto the moveable positive and negative connecting pieces34,32at the other end thereof, respectively. The wires are arranged along the inside surface of the cover12in the form of an arc. The moveable positive and negative connecting pieces34,32are fixed on the cover12respectively, and the stationary positive and negative connecting pieces35,31are fixed on the front and rear sides of the gear box5respectively. When the cover12is mounted on the gear box5, the moveable positive and negative connecting pieces34,32contact with the stationary positive and negative connecting pieces35,31, respectively. Another two positive and negative wires36are connected to the stationary positive and negative connecting pieces35,31at one end thereof and to the PCB assembly at the other end thereof, respectively. The stationary positive and negative connecting pieces35,31are longer in length than the movable positive and negative connecting pieces34,32, so that the moveable positive and negative connecting pieces34,32can slide on the positive and negative static connecting pieces35,31when the working portion10rotates relative to the gripping portion.

To ensure a reliable connection between the connecting pieces, an elastic member33is disposed on the moveable positive and negative connecting pieces34,32respectively for assisting them into contact with the stationary positive and negative connecting pieces35,31.

Referring toFIGS. 1 and 2, it is preferred to dispose the light source30at the lower portion of the working portion10. The light source30is controlled by a switch controlling the motor M and is supplied with power from a battery package40disposed at the bottom portion of the gripping portion20.

In the illustrated embodiment, to prevent the lubricating grease inside the device from leaking out due to the motion of the members, a leakage-preventing device for controlling the grease is provided in the electric tool. As shown inFIGS. 9,5and6, the gear box5has an opening51, hence, when the impact components8in the gear box5are driven to rotate in the gear box5by the transmission gear9, two tabs formed on the periphery of the impact components intermittently strike the output shaft7protruding to the inside of the opening51on the gear box. As a result, the output shaft7can move in a straight reciprocating manner within the working portion10to strike the nails or the like. In addition, since the working portion10of the electric hammer in this embodiment can be rotated relative to the gripping portion20to drive the output shaft7disposed therein to change its position, the opening51of the gear box serves to provide a space for the displacement of the output shaft7.

To avoid the leakage of the lubricating grease in the gear box5from the opening51, the bushing6is disposed at the opening51of the gear box. The profiles of the bushing6and the gear box5are concentric circles, wherein the bushing is encompassed by the gear box5. The output shaft7is connected to the bushing6through the axle hole62formed on the bushing so that the bushing6can be driven to rotate along the inner surface of the gear box5. As a result, the bushing6can move between the first end position (a) and the second end position (b) of the opening51on the gear box. It is noted that, the bushing6can cover the opening51on the gear box5no matter how it rotates, so that the leakage of the lubricating grease can be avoided.

As shown inFIG. 10, since the bushing6may interfere with the transmission gear9protruding into the gear box5, in order to keep away from the gear transmission position of the transmission gear, a notch60is formed on the bushing6, which has a first end61and a second end61separated from each other. To enhance the sealing effect for grease, it is preferred for the above leakage-preventing device to provide a barb-shaped grease-gathering portion on the first end61and/or the second end61of the bushing protruding to the inside of the bushing6. In order to make the length of the bushing6overlapping with respect to the inner surface of the gear box at one end of the opening51on the gear box when the bushing6is rotated to the other end, it is preferred for the above leakage-preventing device to form a groove91at the gear transmission position where the two ends of the notch60on the bushing6may be touched, and one end of the notch60on the bushing6can be embedded into the groove91as illustrated inFIG. 11.

Since the outer surface of the bushing6is engaged with the inner surface of the gear box5, the grease coming off the impact components8to the inner surface of the bushing6will flow back to the gear box5along this inner surface and is not likely to flow out of the gear box along the engagement surface. Certainly, it may be easily conceivable for those skilled in the art that the outer diameter of the bushing6may be slightly larger than the inner diameter of the gear box5so as to enhance the leak tightness of the seal. Referring toFIG. 4, another embodiment of the leakage-preventing device can be seen. Rib portions52are arranged on the gear box5for isolating the transmission gear9from the impact components8, so that the flowing diffusion of the lubricating grease from the transmission area to the striking area can be reduced.

To avoid a failure of connection of the LED due to the leakage of the grease, in the present embodiment a scraping device is disposed on the positive and negative connecting pieces of the circuit respectively. Referring toFIG. 8and taken the scraping device disposed on the negative connecting piece for example, a scraping piece38is disposed on two sides of the moveable negative connecting piece32along the rotation direction thereof respectively, with one end of each scraping piece38being mounted on the cover12and the other end thereof being contacted by the stationary negative connecting piece31. When the working parts1rotates and the stationary negative connecting piece31is adhered with the leaked lubricating grease, the scraping piece38can scrape away the grease immediately to ensure the unobstructed contact between the LED connecting pieces. Moreover, a grease-gathering groove may be formed on the ends of the scraping piece38along the rotating direction respectively for gathering the scraped grease. The scraping device disposed on the positive connecting piece is the same as the scraping device on the negative connecting piece.

While various concepts have been described in detail, it will be appreciated by those skilled in the art that modifications and alternatives to those concepts could be developed in light of the overall teachings of the disclosure. Therefore, it will be appreciated that the particular concepts disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any equivalents thereof.