Tension adjustment device for a chain saw

Information

  • Patent Grant
  • 6532671
  • Patent Number
    6,532,671
  • Date Filed
    Wednesday, November 28, 2001
    23 years ago
  • Date Issued
    Tuesday, March 18, 2003
    21 years ago
Abstract
An adjusting device has a driving disk with two diametrically oppositely formed arcuate tracks formed thereon and a driven plate securely connected to the chain saw and having multiple bosses evenly and horizontally distributed on the driven plate. The two arcuate tracks are alternately received between two adjacent bosses such that when the driving disk rotates, the driven plate is moved linearly, which results in the adjustment of the tension of the chain saw.
Description




FIELD OF THE INVENTION




The present invention relates to a tension adjustment device, and more particularly to a tension adjustment device for a chain saw. The tension adjustment device has a driving disk with two diametrically oppositely formed arcuate tracks formed thereon and a driven plate securely connected to the chain saw and having multiple bosses evenly and horizontally distributed on the driven plate. The two arcuate tracks are alternately received between two adjacent bosses such that when the driving disk rotates, the driven plate is moved linearly, which results in the adjustment of the tension of the chain saw.




BACKGROUND OF THE INVENTION




With reference to

FIG. 5

, a conventional tension adjustment device for a chain saw as disclosed in U.S. Pat. No. 5,491,889 has an adjusting ring A, a dust-proof cap B with a hole B


2


and a projection B


3


, a driving disk C with a central hole C


1


and an arcuate channel C


2


, a driven plate E with a boss E


1


received in the arcuate channel C


2


and two positioning bosses E


2


, a guide F with two positioning holes F


2


corresponding to the two positioning bosses E


2


and a cutout F


3


and a base G with a threaded bolt G


2


and a guide pole G


3


both received in the cutout F


3


. When the adjusting ring A rotates, the driving disk C rotates simultaneously with the adjusting ring A. Because the boss E


1


is received in the arcuate channel C


2


, the driven plate E is moved as well as the guide F, which leads to the adjustment to the tension of the chain saw (not shown).




The adjustment to the tension of the chain saw is based on the engagement between the boss E


1


and the arcuate channel C


2


. Therefore, when an adjustment is required, the shear is focus on the boss E


1


and thus the boss E


1


is easily worn and damaged.




To overcome the shortcomings, the present invention intends to provide an improved tension adjusting device to mitigate or obviate the aforementioned problems.




SUMMARY OF THE INVENTION




The primary objective of the invention is to provide an improved tension adjusting device having a driving disk with two diametrically oppositely formed arcuate tracks formed thereon and a driven plate securely connected to the chain saw and having multiple bosses evenly and horizontally distributed on the driven plate. The two arcuate tracks are alternately received between two adjacent bosses such that when the driving disk rotates, the driven plate is moved linearly, which results in the adjustment of the tension of the chain saw.




Another objective of the invention is to provide an adjusting member with an adjusting knob received therein and multiple first teeth formed on a bottom face thereof and a driven disk with multiple second teeth corresponding to the first teeth and securely formed with the driving disk, such that the rotation of the adjusting plate drives the rotation of the driven disk and thus the movement of the driven plate is moved and adjustment to the tension of the chain saw is accomplished.




Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is an exploded perspective view of the adjusting device for a chain saw;





FIG. 2

is a partial cross sectional view of the assembled adjusting device of the present invention;





FIG. 3

is a top plan view showing the adjusting of the adjusting knob;





FIGS. 4A

to


4


F are operational view showing the relative movement between the driving disk and the driven plate; and





FIG. 5

is an exploded perspective view of a conventional adjusting device.











DETAILED DESCRIPTION OF THE INVENTION




With reference to

FIG. 1

, the tension adjusting device in accordance with the present invention has an adjusting assembly


1


, a driving assembly


2


and a positioning base


3


.




The adjusting assembly


1


has an adjusting knob


11


with a recess


12


defined in a bottom face of the adjusting knob


11


, an adjusting member


14


with a central hole


140


, multiple first teeth


141


formed on a bottom face of the adjusting member


14


, a skirt


143


formed on an outer periphery of the adjusting member


14


and a chamber


144


defined in the adjusting member


14


to communicate with the central hole


140


and a positioning seat


13


corresponding to the recess


12


of the adjusting knob


11


and provided with a through hole


130


corresponding to the central hole


140


of the adjusting member


14


and the recess


12


of the adjusting knob


11


, a flange


131


and two cutouts


132


each oppositely defined in a periphery defining the through hole


130


so as to communicate with the through hole


130


.




The adjusting knob


11


is selectively and rotatably received in the chamber


144


. The positioning seat


13


is so configured that when the positioning seat


13


is received in the recess


12


, there is no relative movement between the adjusting knob


11


and the positioning seat


13


.




After the positioning seat


13


is received in the recess


12


of the adjusting knob


11


, the adjusting knob


11


together with the positioning seat


13


is received in the chamber


144


with the flange


131


engaging the periphery defining the central hole


140


. Then, a fastener


131


such as a screw is employed to extend through the central hole


140


, the cutouts


132


to threadingly secure the engagement of the positioning seat


13


and the adjusting knob


11


. Further, a dust-proof cap


15


is also included in the adjusting assembly


1


, wherein the dust-proof cap


15


has a recessed area


150


with multiple wedges


151


formed on a side face of the recessed area


150


and an opening


152


defined in a bottom face defining the recessed area


150


to communicate with the recessed area


150


.




The adjusting member


14


is received in the recessed area


150


with the skirt


143


clamped by the wedges


151


so as to secure the adjusting member


14


inside the dust-proof cap


15


yet still allow the adjusting member


14


to rotate inside the recessed area


150


. Meanwhile, the through hole


130


communicates the opening


152


and is exposed to the air.




The driving assembly


2


has a driving disk


21


with two diametrically opposite arcuate tracks


211


formed on a bottom face of the driving disk


21


, a driven disk


22


with multiple second teeth


221


formed on a top face of the driven disk


22


to correspond to the first teeth, a driven plate


23


having an elongate channel


231


, multiple bosses


232


oppositely formed to the elongate channel


231


and two opposite first positioning holes


233


and a guide


24


with a path


241


defined to correspond to the channel


231


and two opposite second positioning holes


242


corresponding to the first positioning holes


233


. A chain saw


25


is rotatably mounted on an outer periphery of the guide


24


.




The seat


3


has a platform


31


, a threaded bolt


32


extending from a top face of the platform


31


to correspond to the path


241


and the channel


231


, a guiding plate


33


integrally formed on the platform


31


to correspond to the path


241


and a driving wheel


34


for driving the chain saw


25


to rotate around the guide


24


.




With reference to

FIG. 2

, when the adjusting device of the invention is assembled, the driven disk


22


is mounted with the driving disk


21


and the driven plate


23


and the guide


24


are secured with each other by means of screws


243


screwed into aligned second positioning holes


242


and first positioning holes


233


. After the assembly between the driving disk


21


, the driven disk


22


and the driven plate


23


and the guide


24


, the threaded bolt


32


extends through the path


241


, the channel


231


, the driving disk


21


, the driven disk


22


, the opening


152


, the central hole


140


and a nut


142


that is securely received in the through hole


130


to screw with the adjusting knob


11


and the nut


142


is so configured that there is no relative movement between the nut


142


and the positioning seat


13


after the nut


142


is received in the through hole


130


. When the threaded bolt


32


threadingly extends through the nut


142


, the guiding plate


33


is received in the path


241


and one of the arcuate tracks


211


is received between two adjacent bosses


232


.




Thereafter, when an adjustment to the tension of the chain saw is necessary, the user first loosens the adjusting knob


11


to allow the adjusting member


14


to freely rotate with respect to the adjusting knob


11


, as shown in FIG.


3


. As a result of the rotation of the adjusting member


14


, due to the engagement between the first teeth


141


and the second teeth


221


, the driven disk


22


is also rotated. Because the driven disk


22


and the driving disk


21


are firmly engaged with each other, the driving disk


21


is rotated, which allows one of the tracks


211


that is received between to adjacent bosses


232


to drive the driven plate


23


linearly. Again, because the driven plate


23


is firmly engaged with the guide


24


, the guide


24


is also moved linearly along with the driven plate


23


.




With reference to

FIGS. 4A

to


4


F, when the driving disk


21


rotates, the driven plate


23


moves simultaneously and linearly, which moves the guide


24


in a linear direction and thus an adjustment to the tension of the chain saw


25


is accomplished.




Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.



Claims
  • 1. An adjusting device for a chain saw, the adjusting device comprising:an adjusting assembly having: an adjusting member with a central hole, multiple first teeth formed on a bottom face of the adjusting member, a skirt formed on an outer periphery of the adjusting member and a chamber defined in the adjusting member to communicate with the central hole; an adjusting knob selectively and rotatably received in the chamber of the adjusting member and provided with a recess defined in a bottom face of the adjusting knob to communicate with the chamber and the central hole; a positioning seat securely received in the recess of the adjusting knob and provided with a through hole corresponding to the central hole of the adjusting member and the recess of the adjusting knob, a flange formed to engage with a periphery defining the central hole of the adjusting member; a dust-proof cap having a recessed area defined to receive therein the adjusting member, the positioning seat and the adjusting knob and provided with an opening defined in a bottom face defining the recessed area to communicate with the recessed area; wherein the adjusting member is selectively rotatable inside the recessed area with respect to the adjusting knob and the dust-proof cap; a driving assembly having: a driving disk with two diametrically opposite arcuate tracks formed on a bottom face of the driving disk; a driven disk firmly engaged with the driving disk and provided with multiple second teeth formed on a top face of the driven disk to correspond to the first teeth; a driven plate having an elongate channel, multiple bosses oppositely formed to the elongate, wherein one of the arcuate tracks is received between two adjacent bosses; and a guide securely engaged with the driven plate and provided with a path defined to correspond to the channel and being so adapted that the chain saw is rotatably mounted on an outer periphery of the guide; and a seat having a threaded bolt extending outwardly to extend through the path, the channel, the driving disk, the driven disk, the opening of the dust-proof cap, the central hole of the adjusting member, the through hole of the positioning seat and into the recess of the adjusting knob to selectively and threadingly engage with the adjusting knob, a guiding plate integrally formed to correspond to the path so as to be received in the path and a driving wheel for driving the chain saw to rotate around the guide; whereby the rotation of the adjusting member drives the driven disk to rotate, which allows one of the tracks to move between two adjacent bosses and a linear movement to the driven plate together with the guide is accomplished.
  • 2. The adjusting device as claimed in claim 1, wherein the dust-proof cap has multiple wedges formed on a side face of the recessed area to engage with the skirt of the adjusting member so as that the adjusting member is securely yet rotatable inside the recessed area.
  • 3. The adjusting device as claim 1, the driven plate has two first positioning holes and the guide has two second positioning holes corresponding to the two first positioning holes of the driven plate so that the driven plate is able to securely engage with the guide by fasteners.
  • 4. The adjusting device as claim 2, where in the seat has a guiding plate formed to be received in the path so as to limit the movement of the guide in a linear direction.
US Referenced Citations (4)
Number Name Date Kind
4129943 Bricker Dec 1978 A
5491899 Schlimann et al. Feb 1996 A
5983508 Sundstrom Nov 1999 A
20020124421 Hermes et al. Sep 2002 A1
Foreign Referenced Citations (1)
Number Date Country
294418 Jan 1954 CH