Power tool

Several means 71, 72, 73, 74, and 75 are provided for restricting a relative displacement in a separating direction of half-split housings 50L, 50R. At one or more of several screw-connection parts 60 of the left and right half-split housings 50L, 50R, a press-fitting protrusion 71a is provided in an insertion hole 62a of a boss-receiving part 62 into which a screw-boss part 61 is inserted. By press-fitting the screw-boss part 61 to the boss-receiving part 62, a separation resistance may be introduced between the left and right half-split housings 50L, 50R.

This application claims priority to Japanese patent application serial number 2016-20898, filed on Feb. 5, 2016, the contents of which are herein incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention generally relates to a handheld power tool which may be used to perform various types of work, such as the cutting of materials.

BACKGROUND ART

A multifunction power tool, which is referred to as a multi-tool, can perform various kinds of work such as cutting work, peeling work, and grinding work, etc. by swinging a tip tool attached to an output axis of the power tool at a predetermined angle at high speed. The maximum swinging rate of the output axis may reach roughly 200,000 times per minute, which may cause microvibration. Owing to the microvibration, a problem of, for example, damaged operability and/or workability may occur in these types of power tools. Conventionally, in these types of power tools, various countermeasures have been taken to suppress such microvibration. Japanese Laid-Open Patent Publication No. 2015-229223 discloses a technique of suppressing microvibration in multifunction power tools such that a weight device is attached to one end of a motor shaft while an eccentric shaft for producing a swing movement is positioned at the other end of the motor shaft. Aside from this technique, Japanese Patent No. 4844409 discloses a technique of improving drop-impact strength by providing a thin wall part in a grip in pistol-type electric power tools.

Notwithstanding the aforementioned prior art, it is desirable to further suppress the microvibration occurring in multifunction power tools in which swing movement is performed at high speed. Some of the power tools may be configured such that their housing is integrally molded into a tubular body, or a half-split structure having left and right half-split housings made of resin. In the half-split structure, the microvibration caused by the high-speed swing movement can cause mating surfaces of the left and right half-split housings to vibrate at different phases (vibrate mutually) and/or to rub with each other. As a result, a heat generation problem may occur. Furthermore, in a case where a large amount of heat is generated, an additional problem of vibration welding, may occur.

Thus, due to these difficulties, there is a need in the art to solve the problem of heat generation by suppressing a mutual vibration of mating surfaces of the housing in multifunction power tools where the swing movement is performed at high speed.

SUMMARY

In one exemplary embodiment of the present disclosure, a power tool comprises a first half-split housing and a second half-split housing, and the first half-split housing is configured to be mated to the second half-split housing for screw connection. Furthermore, the first and the second half-split housings includes a relative displacement restriction means other than the screw connection for restricting a relative displacement of the first half-split housing with respect to the second half-split housing in a separating direction.

According to the embodiment, the power tool is provided with the relative displacement restriction means other than the screw connection for restricting the relative displacement of the half-split housings in the separating direction. Because of the relative displacement restriction means, a resistance to separation in the separating direction (separation resistance) is introduced between the half-split housings. Because of this element of construction, even if the screw connection is loosened, the half-split housings remain connected in an inseparable manner due to the separation resistance of the relative displacement restriction means.

Furthermore, the separation resistance which aids the half-split housings in remaining connected in a mating manner with each other dually functions as a resistance for restricting a displacement along the mating surfaces of the half-split housings in a longitudinal direction (a direction perpendicular to the separating direction). Thus, because of the separation resistance generated by the relative displacement restriction means, through the dual-function of the means, a relative displacement (vibration and/or rub) in a mating direction of the half-split housings can also be restricted. As a result, heat generation on the mating surface can be prevented and/or restricted.

In another exemplary embodiment of the disclosure, the first half-split housing includes a screw-boss part for fastening a screw, and the second half-split housing includes a boss-receiving part into which the screw-boss part of the first half is inserted. Furthermore, in this embodiment the relative displacement restriction means is configured by the screw-boss part being press-fitted to the boss-receiving part.

According to the embodiment, by press-fitting the screw-boss part to the boss-receiving part, separation resistance is introduced between the half-split housings. As a result, relative displacement (vibration and/or rub) in the mating direction of the half-split housings can be restricted and/or reduced. In the press-fitting structural configuration, an inner diameter of the boss-receiving part is configured to be sized with respect to an outer diameter of the screw-boss part such that the screw-boss part is press-fit to the boss-receiving part. In another structure, a protrusion is provided on an inner surface of the boss-receiving part such that the screw-boss part is press-fit to the boss-receiving part.

In another exemplary embodiment of the disclosure, the relative displacement restriction means is configured such that a press-fitting pin provided in the first half-split housing is press-fit to a press-fitting hole provided in the second half-split housing.

According to the embodiment, the press-fitting pin positioned between the half-split housings can generate the separation resistance. Because of the separation resistance, a relative displacement along the mating surface of the half-split housings in a longitudinal direction can be restricted. As a result, vibration and/or rub of the mating surface in a mating direction can be restricted, which can prevent and/or restrict heat generation.

In another exemplary embodiment of the disclosure, the first half-split housing includes a first mating surface, and the second half-split housing includes a second mating surface. A rib is provided on the first mating surface for restricting the relative displacement of the first half-split housing with respect to the second half-split housing in a mating direction, and a rib-receiving part into which the rib is inserted is provided on the second mating surface. In this manner, the relative displacement restriction means of this embodiment is structurally configured such that the rib is press-fit to the rib-receiving part.

According to the embodiment, the rib press-fit to the rib-receiving part can generate the separation resistance between the half-split housings. As a result, relative displacement (vibration and/or rub) along the mating surface of the half-split housings in a longitudinal direction can be restricted, which can prevent and/or restrict heat generation.

In another exemplary embodiment of the disclosure, a protrusion is provided on the rib, and the protrusion is configured to be elastically deformed such that the rib is press-fit to the rib-receiving part.

According to the embodiment, the protrusion is elastically deformed to be press-fit to the rib-receiving part. The press-fitting structural configuration of the rib with respect to the rib-receiving part is such that the protrusion is provided on a lateral side of the rib. In another structure, the rib is formed in a tapered manner to be press-fit to the rib-receiving part. In another structure, a groove width of the rib-receiving part is sized to be a little smaller than a thickness of the rib to be press-fit to the rib. Furthermore, in another structure, a elastic member such as a rubber sheet etc. is inserted between lateral sides of the rib and the rib-receiving part such that the rib is press-fit to the rib-receiving part.

In another exemplary embodiment of the disclosure, a plurality of ribs are provided on the first mating surface, and the relative displacement restriction means includes at least three ribs.

According to the embodiment, due to the plurality of ribs, relative displacement (vibration and/or rub) along the mating surfaces of the half-split housings in a longitudinal direction can be restricted in a wider area. As a result, heat generation can be more simply and/or more reliably prevented and/or reduced.

In another exemplary embodiment of the disclosure, the power tool further comprises an output shaft that swings at a predetermined angle. Furthermore, the first half-split housing and the second half-split housing are configured to be located left and right with respect to a place including a swing axis of the output shaft.

According to the embodiment, the above-discussed effects can be applied to the half-split housings in the multifunction power tool having a fast swing output shaft.

DETAILED DESCRIPTION OF EMBODIMENTS

The detailed description set forth below, when considered with the appended drawings, is intended to be a description of exemplary embodiments of the present invention and is not intended to be restrictive and/or to represent the only embodiments in which the present invention can be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other exemplary embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the exemplary embodiments of the invention. It will be apparent to those skilled in the art that the exemplary embodiments of the invention may be practiced without these specific details. In some instances, these specific details refer to well-known structures, components and/or devices that are shown in block diagram form in order to avoid obscuring significant aspects of the exemplary embodiments presented herein.

Hereinafter, exemplary embodiments of the present teachings will be described with reference toFIGS. 1 to 24. As shown inFIGS. 1 to 3, a multifunction electric power tool may be exemplified as a power tool1in each of exemplary embodiments. The power tool1may have a configuration in which a tip tool attached to an output shaft of a motor is swung at a predetermined angle at high speed. The power tool1may be used for various kinds of work such as, for example, a cutting work of plasterboards, a peeling work of tiles, and a grinding work of wooded materials, etc. Hereinafter, five embodiments will be described below. Each of the five embodiments may have differing features from each other with respect to a connection structure of half-split housings, and a basic structure of the housing, with the exception of the above feature may be common in the five embodiments. Because of this reason, only the embodiment 1 will be explained with regard to the basic structure of the power tool1, and the subsequent descriptions of the construction in the other four embodiments in common with the first embodiment may be omitted by using the same reference numerals.

The power tool1may be provided with a tool main body10in which an electric motor11is housed as a driving source, a mechanism section20that is located in front of the tool main body10, a grip30that is located at a rear part of the tool main body10, and a power supply section40that is located at a rear part of the grip30. In the power tool1, the mechanism section20, the tool main body10, the grip30, and the power supply section40may be successively arranged in this order from the front side, extending approximately in a straight line along the front-rear axis. The mechanism20, the tool main body10, the grip30, and the power supply section40may be housed in roughly a tubular housing50that extends along a motor axis M of the electric motor11. The housing50may include left and right half-split housings made from resin. Each of the five embodiments may have a feature in a connection structure of the half-split housings. The housing50may be described in detail later.

As shown inFIG. 3, the electric motor11of the tool main body10may be housed in a tubular motor case11a. A cooling fan11battached to a motor axis11cmay be housed in the motor case11a. An oval exhaust window11dmay be provided at a rear part of the motor case11a. InFIG. 3, the cooling fan11bmay be seen via the exhaust window11d. Furthermore, as shown inFIGS. 1, 4, and 5, a plurality of inlet ports50bmay be provided at a front side face, a center side face, and a rear side face in a longitudinal direction of the housing50. Furthermore, a plurality of exhaust ports50amay be provided at approximately a center side-face in the longitudinal direction of the housing, which is located around the exhaust window11d. When the cooling fan11brotates by the running of the electric motor11, outside air may be introduced into an inside of the motor case11avia the inlet ports50bto cool the electric motor11. This air for cooling the electric motor11introduced into the inside of the motor case11amay be exhausted from the exhaust window11dto the outside of the housing50via the exhaust ports50aby the continued rotation of the cooling fan11b.

The electric motor11may be powered by a battery pack41that is attached to the power supply section40. The mechanism section20may be connected to the motor shaft11cof the electric motor11. The mechanism section20may include a driving shaft22, a swinging arm23, and a member that rotatably supports output shaft24, where the members of the mechanism section are inside a mechanism case21. The driving shaft22may be connected to the motor shaft11cof the electric motor11. The driving shaft22may be rotatably supported by the mechanism case21via bearings22aand22b. The driving shaft22may be rotatably supported around the motor axis M. Furthermore, an eccentric shaft22cthat is eccentrically located with respect to the motor axis M may be integrally formed with the driving shaft22at a front part thereof. A driving roller25may be attached to the eccentric shaft22c.

Operating parts23aof the swinging arm23may be brought into slide contact with the driving roller25in both the left and right directions. The left and right operating parts23amay be integrally formed with a rear part of the swinging arm23. The left and right operating parts23amay extend in the rear direction in parallel at a predetermined space apart from each other. Furthermore, an output shaft24may be joined to a front part of the swinging arm23. The output shaft24may be rotatably supported around an output axis P that is perpendicular to the motor axis M. The output shaft24may be supported by the mechanism case21via an upper bearing24aand a lower bearing24b.

When the electric motor11is run, the driving shaft22may rotate around the motor axis M. When the driving shaft22rotates around the motor axis M, the eccentric shaft22cvia its eccentric orientation revolves around the motor axis M. Consequently, displacement of the driving roller25in the left and right directions due to movement from the eccentric shaft22cmay be transferred to the swinging arm23via the left and right operating parts23awhile the driving roller25revolves around the motor axis M. Thus, the swinging arm23may swing about the output axis P in the left-right directions at a predetermined angle. Because of this movement, the output shaft24may rotate about the output axis P at the same predetermined angle.

A lower part of the output shaft24may protrude in a downward direction from a lower surface of the mechanism case21. A tool holder26may be provided at the lower part of the output shaft24. Furthermore, a tip tool T may be attached to the lower part of the output shaft24by inserting the tip tool T to the tool holder26and tightening a fixing screw26ato fix the tip tool T. The tip tool T may be attached to the lower part of the output shaft24, extending from the lower part of the output shaft24in the front direction (a direction orthogonal to the output axis P). As shown inFIGS. 1 and 2, a band-shaped saw blade (cutting saw blade) may be attached to the output shaft24as the tip tool T. The tip tool T may be swung at high speed at the predetermined angle around the output axis P, and a cutting work may be performed by use of a tip of the tip tool T. For example, a wooden material can be cutout using the tip tool T in a rectangular shape.

A start switch12that is slidably operated in the forward and rearward directions may be provided on the upper peripheral surface of the main body housing51(corresponding to the tool main body10) of the housing50. As shown inFIG. 3, an operation lever13, which is integrally formed with the start switch12, may be located below a lower surface of the start switch12. The operation lever13may extend in the rearward direction along an inner surface of the housing50. A rear portion of the operation lever13may be joined to a main switch14that is housed within the grip30. When the start switch12is slidably operated (moved) in the forward direction (the start switch12is turned on), through the movement of operation lever13, the main switch14may be switched on to run the electric motor11. On the other hand, when the start switch12is slidably operated (moved) in the rearward direction (the start switch12is turned off), through the movement of operation lever13, the main switch14may be switched off to stop the electric motor11.

The grip30, which can be held by a user with one hand, may be located proximate to the rear end of the tool main body10. A grip housing53(corresponding to the grip30) of the housing50may have a thickness and shape such that the user can easily hold the grip30with one hand. A speed controller for adjusting a rotation speed of the electric motor11may be located at the rear part of the grip30. Furthermore, a rotary type adjustment dial31amay be provided at the speed controller31. As shown inFIGS. 2 and 3, an upper part of the adjustment dial31amay protrude from a window53aprovided at an upper surface of the grip housing53. A triangular indicator53bfor indicating an adjusted rotation speed of the electric motor11may be marked in front of the window53a. The window53amay be provided at a bottom part of a rectangular convex flange53cthat is formed in an inverted cone shape, as seen from the plan view inFIG. 2. The upper part of the adjustment dial31amay protrude from the window53ain such a way so as to not protrude from the concave part53c. Because of this configuration, an inadvertent erroneous operation of the adjustment dial31amay be prevented.

The power supply section40may be provided rearward of the grip30. A power supply section housing54, which houses the power supply section40, may be integrally formed with and protrude and tilt in a diagonally downward direction from the grip housing53. A main controller43for controlling the electric motor11may be housed in the power supply section housing54. Although not shown inFIG. 3, the main controller43may be configured such that a control circuit board of the main controller43, which molded with resin and is housed in a shallow rectangular case, comprises a motor control circuit and a power supply circuit.

A terminal stand42having positive and negative terminal plates42amay be housed at the rear surface side of the main controller43. A pair of rail receiving sections44for guiding the battery pack41may be provided at the left and right side directions of the terminal stand42. The battery pack41which is slidably attached to the power supply section40may include a plurality of lithium ion cells housed in a case thereof. For example, the battery pack41may output 10.8 volts. A pair of guide rails41athat engages with the pair of rail receiving sections44of the terminal stand42of the power supply section40may be provided on the front surface of the case comprising battery pack41. Furthermore, positive and negative terminal receiving parts may be arranged between the pair of guide rails41aon the battery pack41.

The battery pack41may be attached to the power supply section40by sliding the battery pack41in the downward direction from an upward starting position relative to the terminal stand. On the other hand, from an attached position, the battery pack41may be removed from the power supply section40by sliding the battery pack41in the upward direction. Although not shown in the figures, a claw part for locking an attachment condition of the battery pack41with respect to the ten final stand of the power supply section40may be provided on the battery pack41. Furthermore, as shown inFIG. 2, an unlock button41bmay be provide on the upper surface of the battery pack41for releasing the attachment lock condition by displacing the claw part to an unlock position relative to the power supply section40. Subsequently, the battery pack41may be removed from the power supply section41and recharged for repeated use by a dedicated charger separately provided.

As discussed earlier, the power tool1may include the tubular housing50extending along the motor axis M, which comprises the left and right half-split housings. The housing50may be configured such that the left half-split housing50L and the right half-split housing50R are mated and screw-connected to each other. The front of the housing50may correspond to a mechanism section housing52of the mechanism section20. The rear of the mechanism section housing52may correspond to the front of main body housing51of the tool main body10. The rear of the main body housing51may correspond to the front of a grip housing53of the grip30. Furthermore, the rear of the grip housing53may correspond to the front of the power supply section housing54of the power supply section40.

As shown inFIG. 2, the left half-split housing50L and the right half-split housing50R ofFIGS. 4 and 5, respectively, may be mated with each other on the mating surface J to form the tubular housing50.FIGS. 4 and 5show the left and right half-split housings50L,50R respectively seen from the right and left internal surface sides, respectively. Both the left and right half-split housings50L,50R may be provided with the mating surface J mainly along upper edge parts and lower edge parts thereof.

Outer circumferential surfaces of the left and right half-split housings50L,50R may be (partly or wholly) covered with elastic resin layer55in order to prevent slippage and/or reduce an impact of dropping etc. InFIGS. 4 and 5, the elastic resin layer55may be indicated by oblique lines in order to differentiate the elastic resin layer55from the mating surface J. Ribs56may be provided on the mating surface J in order to position the mating surface direction of the left and right half-split housings50L,50R (mainly in the upward and downward directions). As shown inFIG. 4, the ribs56may be provided on the mating surface J of the left half-split housing50L. Each of the ribs56may have a thin-plate shape, and a plurality of ribs56may be provided along the mating surface J at appropriate intervals. As shown inFIG. 4, five ribs56may be provided on the upper edge part and two ribs on the lower edge part of the left half-split housing50L (seven ribs56are provided in total).

Corresponding to the location of each of the ribs56on the left half-split housing50L, groove holes58may be respectively provided at corresponding locations on the mating surface J of the right half-split housing50R. Each of the groove holes58may have an appropriate groove width and length such that the opposing and/or corresponding ribs56can be inserted thereinto. As shown inFIGS. 6, 8, and 9, the left half-split housing50L may be mated with the right half-split housing50R by inserting the ribs56into the corresponding groove holes58. In this way, the left and right half-split housings50L,50R may be positioned in the mating direction and the mated housings50L and50R may be screw-connected to each other in the positioned state. Furthermore, the insertion of the ribs56into the corresponding groove holes58may restrict and/or prevent a positional displacement of the left and right half-split housings50L,50R in the mating surface direction, such that vibration etc. may not occur.

An auxiliary rib57may be provided at a lower end of the left half-split housing50L, and an auxiliary rib59at a lower end of the right half-split housing50R. As shown inFIG. 4, two auxiliary ribs57may be provided on the lower end of the mating surface J of the left half-split housing50L. Similarly, as shown inFIG. 5, two auxiliary ribs59may be provided on the lower end of the mating surface J of the right half-split housing50R. Each of the auxiliary ribs57,59may be formed long along the mating surface J (extending in the longitudinal direction). The front auxiliary ribs57and59may be provided along the mating surface J of the main body housing51. The rear auxiliary ribs57and59may be provided along the mating surface J from the grip housing53to the power supply section housing54.

As shown inFIGS. 6, 8, and 9, the auxiliary ribs57of the left half-split housing50L and the corresponding auxiliary ribs59of the right half-split housing50R may be overlapped with each other in the left-right direction. Because of this overlapping construction, a positioning and/or a displacement prevention of the left half-split housing50L with respect to the right half-split housing50R may be performed in the upward and downward directions of the mating surface J. With regard to a structural configuration in which the auxiliary ribs57of the left half-split housing50L are overlapped with the auxiliary ribs59of the right half-split housing50R in the left-right direction, along the thickness of the tubular housing, the same configuration may be adopted in other embodiments discussed infra.

As shown inFIG. 1, the left and right half-split housings50L,50R may be screw-connected with each other where the components of the screw connection comprise screw-connection parts60, at nine locations in total. Each of the screw-connection parts60may comprise a screw-boss part61included on the left half-split housing50L, a boss-receiving part62included on the right half-split housing50R, and a screw63for screw-connecting the left and right half-split housings50L,50R.

As shown inFIG. 4, nine screw-boss parts61each having a screw hole61afor fastening the screws63may be provided on the inner surface of the left half-split housing50L as seen from the right side. Each of the screw-boss parts61may be provided in a protruding direction from the inner surface of the left half-split housing50L toward the right half-split housing50R, with which the left half-split housing50L mates. Furthermore, the screw hole61ahas a predetermined depth and may be provided on the protruding side. Three screw-boss parts61may be provided on the inner surface of the mechanism section housing52of the left half-split housing50L. Two screw-boss parts61may be provided on the inner surface of the main body housing51of the left half-split housing50L. Two screw-boss parts61may be provided on the inner surface of the grip housing53of the left half-split housing50L. Furthermore, two screw-boss parts61may be provided on the inner surface of the power supply section housing54of the left half-split housing50L. Furthermore, in addition to the three screw-boss parts61provided on the mechanism section housing52, three case-fixing parts64each having a screw hole64afor fixing the mechanism section case21may be provided on the inner surface of the mechanism section housing52of the left half-split housing50L.

As shown inFIG. 5, nine boss-receiving parts62in total may be provided on the inner surface of the right half-split housing50R, corresponding to the nine screw-boss parts61of the left half-split housing50L. Each of the boss-receiving parts62may have a cylindrical shape such that the screw-boss part61can be inserted thereinto. An insertion hole62afor inserting the screw63may be provided at a bottom center of each boss-receiving part62. By inserting the screw63into the insertion hole62afrom the right half-split housing50R and fastening the screw63to the screw hole61aof the left half-split housing50L, the left half-split housing50L may be firmly connected to the right half-split housing50R in a mating manner to jointly form the tubular housing50. Conversely, when all of the screws63are removed from the nine screw-connection parts60, the left half-split housing50L may be separated from the right half-split housing50R.

A means for restricting a displacement in a mutual separation direction (hereinafter, referred to as a relative displacement restriction means70) may be provided between the left half-split housing50L and the right half-split housing50R. Hereinafter, several embodiments with respect to the relative displacement restriction means70may be described below. As shown inFIGS. 5 to 7, a relative displacement restriction means71of the first embodiment may be configured such that a press-fitting protrusion71amay be provided on an inner surface of the boss-receiving part62. The press-fitting protrusion71amay be provided at an upper screw-connection part60of the two screw-connection parts60that are located in the grip housing53of the right half-split housing50R. A degree of rub and/or vibration, which may potentially occur without the displacement restriction means between the mating surface J of the left and right half-split housings50L,50R, would be presumed to be larger in the vicinity of the upper screw-connection part60. As a result, the relative displacement restriction means71is provided at this place in the first embodiment.

In the upper screw-connection part60of grip housing53of the right half-split housing50R, four press-fitting protrusions71amay be provided on the outer periphery of the inner circumferential surface of the boss-receiving part62at equal intervals (four protrusions equally spaced in the circumferential direction). Due to the presence of the press-fitting protrusions71aon the outer periphery of the inner circumferential surface, an (actual) inner diameter of the upper boss-receiving part62may become smaller than that of the other eight boss-receiving parts62. Hence, the inner diameter of the upper boss-receiving part62may be appropriately sized such that the protruding tip part of the screw-boss part61of the left half-split housing50L can be inserted thereinto.

Because of this configuration, in a state where the left and right half-split housings50L,50R are connected to each other, the screw-boss part61may be press-fit to an inner peripheral hole of the boss-receiving part62in the upper screw-connection part60located in the grip housing53. On the other hand, for the other eight screw-connection parts60, each of the corresponding screw-boss parts61may be inserted into the corresponding inner peripheral holes of the corresponding boss-receiving part62without any resistance. In this way, in one of the nine screw-connection parts60(the upper screw-connection part60located in the grip housing53), the screw-boss part61may be press-fit to the screw-receiving part61because of the press-fitting protrusions71a. In this manner, a resistance in the separating direction (separation resistance) may be generated between the left and right half-split housings50L,50R. Thus, even if all of the screws63are loosened in the screw-connection parts60, the left and right half-split housings50L,50R may still be kept in a mating configuration with respect to each other, with the retaining force of the separation resistance of the upper screw-connection part60located in grip housing53present. In the first embodiment, the separation resistance by the press-fitting protrusions71a(a retaining force for retaining the housings in the mating manner) may be configured such that when, for example, the housing50is held in a horizontal left-to-right direction with only one of the half-split housings being held by the user, the other of the half-split housings may not be separated (may not fall) due to its own weight by gravity. In the first embodiment, a protruding size of the four press-fitting protrusions71ain the direction of the inner diameter from the outer periphery of the inner circumferential surface of the boss receiving part62may be appropriately set in order to generate the separation resistance desired.

The separation resistance for retaining the left and right half-split housings50L,50R in the mating configuration (with press-fit separation resistance present) with respect to each other may also dually serve as a resistance for restricting a displacement of the left and right half-split housings50L,50R in the mating surface direction J (in a direction perpendicular to the separation direction). Due to the nature of the separation resistance obtained by the press-fitting protrusions71a(relative displacement restriction means70) via the press fit structural configuration as described, a relative displacement (rub and/or vibration) of the left and right half-split housings50L,50R may be restricted in the direction of the mating surface J, which effectively prevents and/or restricts heat from generating on the mating surface J.

According to the relative displacement restriction means71in the first embodiment discussed above, the screw-boss part61may be press-fit to the inner circumferential surface of the boss-receiving part62in one of the nine screw-connection parts60as described above, by which the left and right half-split housings50L,50R are connected with each other (are not easily separated from each other). Under the press-fitting condition, the appropriate resistance (separation resistance) may be obtained between the left and right half-split housings50L,50R through configuration of the press-fit configuration and sizing of protrusions71aas described above. Because of the presence of the separation resistance, the relative displacement of the left and right half-split housings50L,50R may be restricted in the direction of the mating surface J. Thus, rub and/or vibration on the mating surface J can be restricted, which may restrict heat generation.

FIG. 8shows a relative displacement restriction means72of a second embodiment. The relative displacement restriction means72of the second embodiment may be configured such that instead of the four press-fitting protrusions71a, a tubular rubber bush72ais inserted into and/or fittedly mounted to the outer periphery of the inner circumferential surface of the boss-receiving part62. The tip end of the screw-boss part61may then be press-fit to the inner circumferential surface of the rubber bush72a. In this way, as with the first embodiment, separation resistance may be generated in one of the screw-connection parts60of the left and right half-split housings50L,50R.

As discussed above, because of the relative displacement restriction means72(the rubber bush72a) of the second embodiment, the separation resistance may be generated between the left and right half-split housings50L,50R. Because of this separation resistance, the relative displacement of the left and right half-split housings50L,50R may not only be restricted in the horizontal left-to-right direction, but may also be restricted in the longitudinal direction of the mating surface J. Thus, rub and/or vibration of the mating surface J can be restricted, which may restrict heat generation.

FIGS. 9 and 10show a relative displacement restriction means73of a third embodiment. The relative displacement restriction means73of the third embodiment may be configured such that the separation resistance can be generated between the left and right half-split housings50L,50R by use of a press-fitting pin73a. In the third embodiment, the press-fitting pin73amay be press-fitted between the mating surface J of the left and right half-split housings50L,50R along and/or in the vicinity of the upper screw-connection part60located in the grip housing53. Because of the press-fitting pin73a, the separation resistance, as present in the other embodiments above, may be obtained between the left and right half-split housings50L,50R. As a result, the relative displacement may not only be restricted in the horizontal left-to-right direction, but may also be restricted in the direction of mating surface J, where rub and/or vibration between the mating surface J of the left and right half-split housings50L,50R can be restricted, which may restrict heat generation.

FIGS. 11 to 14shows a relative displacement restriction means74of a fourth embodiment. The relative displacement restriction means74of the fourth embodiment may be configured such that instead of the press-fitting pin73a, a rib56of the left half-split housing50L may be press-fit to a groove hole58of the right half-split housing50R, which generates separation resistance between the left and right half-split housings50L,50R. In the fourth embodiment, a rubber sheet74amay be attached to the rib56to obtain a necessary press-fitting margin to contact the inner peripheral surface of the groove hole58. The rubber sheet74amay be attached to both the outside and inside surfaces of the rib56(upside and downside surfaces of the rib56as shown inFIG. 12). As shown inFIGS. 11 and 12, the rubber sheet74amay be attached to the both sides of the rib56, and the rib56with the rubber sheet74amay be press-fit to the groove hole58. By press-fitting the rib56with the rubber sheet74ato the groove hole58, the separation resistance may be generated between the left and right half-split housings50L,50R. As a result, the relative displacement may not only be restricted in the horizontal left-to-right direction, but may also be restricted in the direction of mating surface J, where rub and/or vibration (relative displacement) between the mating surface J of the left and right half-split housings50L,50R may be restricted, and thus heat generated in this area may be restricted.

FIGS. 15 and 16show a relative displacement restriction means75of the fifth embodiment. The relative displacement restriction75of the fifth embodiment may be configured such that a thickness of the rib56of the left half-split housing50L in the grip housing53, relative to the rib56of the fourth embodiment described above, is increased to obtain a necessary a press-fitting margin. InFIGS. 15 and 16, a symbol W may be added to the rib56whose thickness is increased to add the press-fitting margin. In the fifth embodiment, the rubber sheet74amay not be attached to the rib56to obtain the press-fitting margin unlike in the fourth embodiment, but the thickness of the rib56itself may be increased (the rib56having an increased thickness may be formed by molding) to obtain the press-fitting margin to contact the inner peripheral surface of groove hole58on its own. By press-fitting the rib56W to the groove hole58, the relative displacement restriction may be obtained between the left and right half-split housings50L,50R. As a result, in the fifth embodiment, the relative displacement may not only be restricted in the horizontal left-to-right direction, but may also be restricted in the direction of mating surface J, where rub and/or vibration (relative displacement) between the mating surface J of the left and right half-split housings50L,50R may be restricted, and thus heat generation may be restricted.

As discussed above, the rubber sheet74may be attached to the rib56in the fourth embodiment and the thickness of the rib56itself may be increased in the fifth embodiment in order to press-fit the (positioning) rib56provided on the mating surface J to the groove hole58. Other than the aforementioned embodiments, an additional relative displacement restriction means (press-fitting structure) embodiment may be adopted as shown inFIGS. 17 to 19. The press-fitting structure shown inFIG. 17may be such that a plurality of protrusions56aare provided on a surface of the rib56or both surfaces of the ribs56to obtain the necessary press-fitting margin. By press-fitting the rib56having the protrusions56ato the groove hole58, the separation resistance may be generated between the left and right half-split housings50L,50R. As a result, the relative displacement may not only be restricted in the horizontal left-to-right direction, but may also be restricted in the direction of mating surface J, where rub and/or vibration on the mating surface J may be restricted, and eventually heat generation in this area may be restricted.FIG. 17shows four protrusions56a, but more than four protrusions may be provided to obtain the press-fitting margin. Other than this configuration, for example, another configuration in which only one protrusion is provided on either one surface of the rib56may be adopted.

Furthermore, as shown inFIG. 18, instead of the protrusion(s)56adiscussed above, the necessary press-fitting margin may be obtained by providing a projection56bextending in a longitudinal direction of the rib56on a surface or both surfaces of the rib thereof.FIG. 18shows one projection56bon one surface of the rib56, but the projection56bmay be provided on the opposite side as well, thus being present on both surfaces of the rib56. Furthermore, other constructions in which a plurality of projections are provided on one surface of the rib56in order to obtain the necessary press-fitting margin may be contemplated.

FIG. 19shows another press-fitting structure (an additional relative displacement restriction means embodiment). The press-fitting structure shown inFIG. 19may be configured such that a rib56T formed in a tapered shape is press-fitted to the groove hole58to generate the separation resistance between the left and right half-split housings SOL,50R. A thickness of the rib56T may be continuously reduced (i.e. may be tapered) toward its extending tip side. By press-fitting the tapered rib56to the groove hole58, the separation resistance may be generated between the left and right half-split housings50L,50R. As a result, the relative displacement may not only be restricted in the horizontal left-to-right direction, but may also be restricted in the direction of mating surface J, where rub and/or vibration on the mating surfaces J may be restricted, and eventually heat generation may be restricted.

As discussed above, the relative displacement restriction means71,72,73,74, and75may provide the separation resistance in the left and right half-split housings SOL,50R in order to restrict not only relative displacement in the horizontal left-to-right direction, but also relative displacement (rib and/or vibration) between the mating surface J, which eventually restricts heat from being generated. In the press-fitting configurations of the second to fifth embodiments and those shown inFIGS. 17 to 19, the separation resistance between the left and right half-split housing50l,50R (the retaining force for retaining the housings in the mating manner) may be configured such that when, for example, the housing50is held in a horizontal direction with only one of the half-split housings being held, the other of the half-split housings may not be separated (may not fall) due to its own weight. In addition, the relative displacement may not only be restricted in the horizontal left-to-right direction, but may also be restricted in the direction of mating surface J, where because of this configuration, rub and/or vibration between the mating surfaces J may be effectively reduced, which can restrict heat from being generated.

In the first embodiment, the relative displacement restriction means71may be provided in the upper boss-receiving part62of the grip housing53. However, the relative displacement restriction means71of the first embodiment may be provided in another boss-receiving part62or in a plurality of boss-receiving parts62selected from the nine boss-receiving parts62in total such that the separation resistance can be generated. Similarly, this alternate or plural placement of the means may also be applied to the press-fitting structure of the second to fifth embodiments. In the second to fifth embodiments, the press-fitting margin may be provided in the upper edge side rib56of the grip housing53, or the press-fitting pin73amay be inserted in the vicinity of the rib56. However, the exemplified press-fitting structure may be applied to the other rib56or a plurality of ribs56selected from the seven ribs56in total.

In the above-discussed embodiments, the press-fitting margin may be provided in the rib56. However, instead of the ribs56, the press-fitting margin may be provided in the groove hole58into which the rib56is inserted.

In addition to the above discussed relative displacement restriction means, countermeasures against vibration and/or countermeasures for absorbing impacts at the time of falling etc. may be taken in the embodiments of the power tool1.FIG. 20shows a means for restricting vibration of the housing50transferred from the mechanism section20. A first impact absorption member81may be provided on the internal surface of the left and right half-split housings50L,50R. In more detail, the first impact absorption member81may be provided on the front side of the mechanism section housing52of the housing50. As shown inFIG. 20, the first impact absorption member81may be provided in a substantially bilaterally symmetrical manner around the mechanism section housing21of the left and right half-split housings50L,50R. As shown inFIGS. 5 and 20, the first impact absorption member81may include four absorbing protrusions81aon each side, for the left and right sides. The four absorbing protrusions81amay be arranged at appropriate angular intervals and in a parallel configuration relative to each other in a circumferential direction, each extending in the forward and rearward directions. The four absorbing protrusions81amay be formed integrally with an outer-surface-side elastic resin layer55by double molding at the time of molding of the half-split housings. The same elastic resin as used in the outer-surface-side elastic resin layer55may also be used in the four absorbing protrusions81a.

In assembling of the mechanism section20with regard to the housing50, each of the absorbing protrusions81aat the front side52of the mechanism section housing may be pressed against an outer surface of the mechanism case21. In this configuration, the mechanism case21may thus support the housing50via the left and right first impact absorption member81. Because of the first impact absorption member81, vibration generated in the mechanism section20, and in particular vibration caused by swing movement of the swinging arm23, may be absorbed, and eventually vibration of the housing50may be reduced. Furthermore, because of the first impact absorption member81, vibration of the left and right half-split housings50L,50R may be reduced, and thus rub and/or vibration on the mating surface J may be reduced. As a result, heat generated in this area may be restricted.

Furthermore, as shown inFIG. 21, a second impact absorption member82for absorbing vibration of the electric motor11may be provided on the inner surface of the left and right half-split housings50L,50R. The second impact absorption member82may be provided in the main body housing51of the housing50. The second impact absorption member82may comprise a pair of rubber sheets82aprovided along the inner surface of left and right half-split housings50L,50R. In assembling of the electric motor11with regard to the housing50, the pair of rubber sheets82ahaving appropriate elasticity may be pressed against the outer circumferential surface of the motor case11a. Because of this construction, vibration occurring in the electric motor11may be absorbed, and eventually vibration of the housing50may be reduced. By reducing vibration of the left and right half-split housings50L,50R through the absorption by the second impact absorption member82, rub and/or vibration on the mating surface J may be reduced, and eventually heat generated in this area may be restricted.

As shown inFIG. 22, a pair of ventilation seals83for closing a gap between an outer surface of the motor case11aand the internal surface of the right and left half-split housings50L,50R may be provided in the main body housing51of the housing50. The ventilation seal83may be circumferentially provided along the inner periphery of the left and right half-split housings50L,50R.

Because of the pair of ventilation seals83, the gap between the outer surface of the motor case11aand the internal surface of the right and left half-split housings50L,50R may be closed in front of the exhaust window11d. As a result, because the gap is closed in front of the exhaust window11d, the air that is exhausted from the exhaust window11dcannot flow in the forward direction, which thereby prevents the exhaust air from entering again into the motor case11a. In this respect, due to the presence of the ventilation seals83, exhaust efficiency of the electric motor11can be improved, and further cooling efficiency of the electric motor11can be improved. Furthermore, by arranging similar ventilation seals to83at the back of the exhaust window11d, exhaust and/or cooling efficiency of the electric motor11may be further improved.

At the time of molding elastic resin layer55covered on the outer surface of the housing50, the pair of ventilation seals83amay be formed (molded) by pouring molten resin material via resin casting ports50cprovided in the left and right half-split housings50L,50R to the inner face side thereof. In this manner of molding construction, the pair of ventilation seals83amay be simultaneously formed by the same material as the elastic resin layer55located outside the ventilation seals83a.

As shown inFIG. 23, a fourth impact absorption member84for reducing vibration of the speed controller31and reducing impact of dropping the housing50may be provided on the inner side of the left and right half-split housings50L,50R at the rear of the main body housing51of the housing50. The fourth impact absorption member84may be provided with a pair of cushioning elements84athat are in contact with the left and right sides of the speed controller31. The speed controller31may be cushioned against the inner periphery of the housing50and supported by the cushioning elements84athat are in contact with the left and right sides of the speed controller31. Because of this construction of cushioning elements, the vibration attributed to and/or of the speed controller31may be reduced, and in case the device is dropped, an impact of the dropping of the housing50upon the speed controller31may also be reduced. As a result, durability and/or reliability of the speed controller31can be improved and also malfunction of the speed controller31can be prevented.

Similar to the molding formation of the ventilation seals83as described above, at the time of molding elastic resin layer55covered on the outer surface of the housing50, the cushioning elements84aof the fourth impact absorption member84may be formed (molded) by pouring molten resin material via resin casting ports50dprovided in the left and right half-split housings50L,50R to the inner face side thereof. In this manner, the cushioning elements84amay be simultaneously formed by the same material as the elastic resin layer55located outside the cushioning elements84a.

As shown inFIG. 24, a fifth impact absorption member85for reducing vibration of the main controller43may be provided on the inner surface of the left and right half-split housings50L,50R of the power supply section housing54of the housing50. The fifth impact absorption member85may be provided with four cushioning elements85ain total that are in the vicinity of and in contact with each corner of the main controller43. Each of the cushioning members85amay be formed in a block shape. Similar to the ventilation seals83and the fourth impact absorption member84, the cushioning elements85aof the fifth impact absorption member85may be simultaneously formed by pouring molten resin material via resin casting ports at the time of molding elastic resin layer55. The main controller43may be cushioned against the inner periphery of the housing50and supported by the cushioning elements85athat are in contact with the left and right sides of the main controller43. Because of this construction, vibration of the main controller43may be reduced, and in case the device is dropped, an impact of dropping the housing50on the main controller43may also be reduced. As a result, durability and/or reliability of the main controller43can be improved and also malfunction of the main controller43can be prevented.

The present invention is not limited to the embodiments discussed above and may be further modified without departing from the scope and spirit of the present teachings. In the first and second embodiments of the present disclosure, the screw-boss part61may be configured to be press-fit into the insertion hole62aof the boss-receiving part62in the upper screw-connection part60of the grip housing53. However, the press-fit construction discussed above is not limited to this configuration and may be applied to another screw-connection part60as well. Furthermore, the press-fit construction may be applied to a plurality of screw-connection parts60, for example, three screw-connection parts60.

In the first embodiment of the present disclosure, the press-fitting protrusion71amay be provided in the insertion hole62aof the boss-receiving part62, and in the second embodiment, the rubber bush72amay be inserted into the insertion hole62a, in order to press-fit the screw-boss part61into the insertion hole62of the boss-receiving part62. However, the screw-boss part61may instead be configured to have the press-fitting margin to press-fit into the insertion hole62aof the boss-receiving part62. Furthermore, the screw-boss part61may be configured to be formed in a tapered shape to press-fit into the insertion hole62aof the boss-receiving part62.

In the third embodiment, the press-fitting pin73amay be press-fit between the left and right half-split housings50L,50R in the vicinity of the upper screw-connection part60of the grip housing53. However, the press-fitting pin73ais not limited to this configuration, and may instead be located in the vicinity of another screw-connection part60, and furthermore a plurality of press-fitting pins formed in a similar shape to the pin73amay be press-fit between the left and right half-split housings50L,50R.

In the fourth and fifth embodiments, the upper edge side rib56of the grip housing53may be press-fit to the groove-hole58. However, instead of this figuration, the rib56located in another portion of the device may be press-fit to its respective groove hole, and furthermore a plurality of the ribs56may be press-fit to the groove-holes, in order to generate separation resistance between the left and right half-split housings50L,50R. The point is that the relative displacement restriction means70may be applied to the mating surface J where large degree of rub and/or vibration might occur, such that an adequate separation resistance can be generated between the left and right half-split housings50L.50R, whereby rub and/or vibration may be reduced on the mating surface direction of the mating surface J to restrict heat generation.

In the embodiments, the multifunction power tool described may represent an exemplary embodiment of the power tool. However, the present teaching is not limited to this embodiment, and may also be applied to vibration drills, screw fastening devices, cutting devices, and any other electric power tools. Furthermore, instead of the battery pack, the present teaching may be applied to the power tool in a case where power may be supplied to the power tool by a mains AC power source such as a 100V commercial power source.

In the embodiments, the half-split structure represented by the described left and right half-split housings50L,50R may represent an exemplary embodiment of the housing50of the power tool1. However, the relative displacement restriction means70may be applied to another case where a front housing is mated to a front portion of a tubular main body housing, a main body housing is mated to a rear portion of the rear housing, or left and right half-split housings of a grip housing are mated with each other, whereby rub and/or vibration on the mating surface may be reduced and heat generation may be prevented.