Cutlery – Cutting tools – Saw
Reexamination Certificate
2001-12-13
2003-11-11
Payer, Hwei-Siu (Department: 3724)
Cutlery
Cutting tools
Saw
C173S162200
Reexamination Certificate
active
06643939
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a chain saw having vibration-isolating devices, capable of providing an improved vibration-isolating effect over a wide frequency range thereby reducing deviation from a desired cutting line.
BACKGROUND OF THE INVENTION
In Japanese Utility Model Publication No. Sho 63-21362, disclosed is a chain saw in which a main body with a two-stroke cycle internal combustion engine, a saw chain guide plate, etc. is mounted via an elastic member to a frame member having front and rear handles, etc.
Japanese Registered Utility Model Publication No. 2598703 also discloses a chain saw which has a mounting structure using a vibration-isolating coil spring for mounting a main body with a power source, such as an internal combustion engine, to a frame member with a grip handle, etc.
Further, Japanese Registered Patent Publication No. 2931025 discloses another chain saw wherein is adapted to make a significant difference between one side and the other side of a driving motor in terms of the sum of products derived from multiplying the spring stiffness values of vibration-isolating elements supporting the driving motor by the distances between each of the vibration-isolating elements and the center of a cylinder of the driving motor, so as to provide enhanced vibration-isolating effect.
However, the vibration-isolating mechanisms disclosed in the Japanese Utility Model Publication No. Sho 63-21362 and the Japanese Registered Utility Model Publication No. 2598703 suffer from an undesirable deviation from an intended cutting line in a sawing operation of an object to be cut (i.e. the object cannot be adequately cut along a straight line) due to inferior balance of the static stiffness between the vibration-isolating elements disposed in the chain saw. Furthermore, in these vibration-isolating mechanisms, respective vibration-isolating effects yielded from the vibration-isolating elements are effective only in the same frequency range, and it is thereby impossible to obtain a sufficient vibration-isolating effect over a wide frequency range. As a result, in a frequency range in which a sufficient vibration-isolating effect from the vibration-isolating mechanisms can not be obtained, undesirable vibration is transmitted to the front and rear handles substantially without receiving any damping effect.
On the other hand, the vibration-isolating mechanism disclosed in the Japanese Registered Patent Publication No. 2931025 has a significantly different static stiffness between the vibration-isolating elements arranged on the right and left sides of the driving motor. This causes undesirable deviation from an intended cutting line in a sawing operation using the chain saw. In addition, the vibration-isolating mechanism disclosed in the same Publication gives no consideration to the frequency range for each of the vibration-isolating elements to provide a vibration-isolating effect. Thus, this mechanism is also incapable of achieving a sufficient vibration-isolating effect over a wide frequency range.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a chain saw with vibration-isolating devices, capable of providing an improved vibration-isolating effect over a wide frequency range thereby reducing deviation from a desired cutting line.
The above object can be achieved by way of a chain saw comprising: a main body; a prime mover arranged within the main body and having a driveshaft extending in a lateral direction of the chain saw; a saw chain extending from the main body in a forward direction of the chain saw; a frame member; a grip handle mounted on the frame member; and at least two vibration-isolating devices each interposed between the main body and the frame member to support the main body with respect to the frame member, two of the vibration-isolating devices are disposed at a space from each other in the forward direction, each of the two vibration-isolating devices including a pair of first and second vibration-isolating members which are different in frequency range in which a vibration-isolating effect is provided, the pair of first and second vibration-isolating members being disposed in series with and being spaced apart from each other in an axial direction of the driveshaft of the prime mover, and the two vibration-isolating devices are disposed such that the respective first vibration-isolating members are positioned in a first diagonal relationship and the respective second vibration-isolating members are positioned in a second diagonal relationship.
The present invention operates as follows. When a certain vibration is caused in the main body by driving the prime mover provided in the main body, the vibration energy is absorbed by the first and second vibration-isolating members. Thus, the vibration energy to be transmitted to the frame member is reduced. In addition, the first and second vibration-isolating members are different in frequency range for providing a vibration-isolating effect bringing about their respective vibration-isolating effects without interfering with each other.
Generally, a vibration-isolating member has a limited frequency range for providing a vibration-isolating effect. It is known, for example, that the vibration-isolating member employing a rubber material is typically effective in isolating vibration in a relatively low frequency, and the vibration-isolating member employing a spring is typically effective in isolating vibration in a relatively high frequency. However, a vibration-isolating device providing a desirable vibration-isolating effect over a wide frequency range is not achieved by simply combining two of the vibration-isolating members which are different in a frequency range for providing a vibration-isolating effect. The afore-mentioned object of the present invention is best achieved if different kinds of first and second vibration-isolating members are arranged substantially in series with each other and are combined in a balanced manner, such that the first and second vibration-isolating members are set up with their different frequency ranges for providing a vibration-isolating effect.
In addition, by arranging the paired first vibration-isolating members and the paired second vibration-isolating members respectively in first and second diagonal relationships, well-balanced supporting ability is provided on the right and left sides of the chain saw, and thereby accidental deviation from a desired cutting line will be reduced.
Preferably, the main body includes a guide-plate supporting portion for supporting a chain guide plate for guiding the saw chain, wherein one of the first and second vibration-isolating members having a lower static stiffness than that of the other of the first and second vibration-isolating members is disposed in the vicinity of the guide-plate supporting portion.
With this construction, the vibration-isolating member having a higher static stiffness is disposed at a position spaced apart from the guide-plate supporting portion. This makes it possible to generate a larger moment of force against the static force acting on the guide-plate supporting portion. Thus, the frame member can stably support the main body, and thereby accidental deviation from a desired cutting line will be further reduced.
Further, the above object can be achieved by A chain saw comprising: a main body; a prime mover having a driveshaft which extends in a lateral direction of the chain saw; a saw chain extending from the main body in the forward direction of the chain saw; a frame member; a grip handle mounted on the frame member; and at least four vibration-isolating devices, each interposed between the main body and the frame member to support the main body with respect to the frame member; the four vibration-isolating devices being formed in two pairs, each comprised of two of the vibration-isolating devices, the two pairs of vibration-isolating devices being disposed spaced apart from each other in the longitudinal direction of the chain saw, the
Nara Masato
Ohsawa Hisato
Tajima Katsuya
Kioritz & Corporation
Nixon & Peabody LLP
Payer Hwei-Siu
Studebaker Donald P.
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