Cutlery – Cutting tools – With blade moving means
Reexamination Certificate
1999-05-28
2001-01-23
Payer, Hwei-Siu (Department: 3724)
Cutlery
Cutting tools
With blade moving means
C056S011300
Reexamination Certificate
active
06176016
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to improvements in an operation control lever unit for regulating power of an engine of an engine-powered working machine, such as a portable bush cutter, to control operation of a working tool of the working machine.
2. Description of the Related Art
Typical examples of known operation control lever units of the type concerned are disclosed in Japanese Patent Publication No. SHO 57-21962, entitled “BUSH CUTTING MACHINE WITH SAFETY DEVICE” and Japanese Utility Model Publication No. 57-42261, entitled “CUTTER BRAKING DEVICE FOR BUSH CUTTER”.
The bush cutting machine disclosed in Japanese Patent Publication No. SHO 57-21962 includes an operation control lever unit having a throttle lever and a brake release lever pivotally mounted on an upper end portion and a lower end portion, respectively, of an operation handle in such a manner that areas of pivotal movement of the two levers overlap with each other. The operation handle is continuously gripped with a hand of the operator during operation of the bush cutting machine. During that time, the throttle lever is depressed by the index finger to adjust power of an engine of the bush cutting machine while the brake released lever is held in its fully depressed position using the middle, third and little fingers so as to keep the a circular cutter free from braking force. When a grip on the operation handle is released, the brake release lever returns to its original braking position during which time the free end of the brake lever comes into engagement with a free end of the throttle lever, then forcing the throttle lever to return to its original throttle full-close position (idling position).
In the disclosed operation control lever unit, since the throttle lever and the brake release lever are both provided on the same side of the operation handle, all the fingers of the operator's hand should be used for manipulation of the two levers (including frequent depressing and releasing of the throttle lever) while keeping the necessary grip on the operation handle. This operation exerts a great load on the fingers of the operator's hand, making it difficult to continue the bush removing work for a long time while keeping a desired position of the circular cutter. The conventional bush cutting machine is therefore unable to achieve a high working efficiency.
The bush cutter disclosed in Japanese Utility Model Publication No. 57-42261 includes an operation control lever unit having a throttle lever pivotally mounted to an upper portion of an operation handle, and a brake release lever rotatably mounted to a lower portion of the operation handle in symmetric relation to the throttle lever about the axis of the operation handle. In use of the bush cutter, the operation handle is gripped with one hand of the operator in such a manner that the throttle lever and the brake lever can be manipulated by the index finger and the palm, respectively of the same hand. To place the throttle lever in the operative condition, the brake release lever is turned about the axis of the operation handle in one direction to release a brake mechanism acting on the power transmission line between an engine and a circular cutter of the bush cutter. This operation requires the operator to bend the wrist while keeping a sufficient grip on the operation handle.
The disclosed operation control lever unit has a drawback that since operation of the brake release lever requires bending of the operator's wrist, the wrist soon becomes fatigued and sometimes is damaged. Bending of the wrist may further limit variations in the posture available for the circular cutter during bush cutting operation. Additionally, if the operator unintentionally unbent his wrist while depressing the throttle lever, the brake release lever is allowed to return to its original braking position, thus forcibly terminating the throttle adjusting operation.
Furthermore, since the fulcrum of each lever is disposed exteriorly of the operation handle, both of the conventional operation control lever units are defective from the asthetical point of view.
SUMMARY OF THE INVENTION
With the foregoing drawbacks in view, it is accordingly an object of the present invention to provide an operation control lever unit for an engine-powered working machine, which is easy to manipulate and hence can lessen loads on the operator, is reliable in operation, is relatively compact in size, and is attractive from the esthetical point of view.
According to the present invention, there is provided an operation control lever unit provided on an elongated support rod of an engine-powered portable working machine including an engine attached to one end of the elongated support rod, a working tool attached to the other end of the support rod and operatively connected for driven relation to the engine, and a brake mechanism associated with the support rod for braking the working tool. The operation control lever unit is adapted to be gripped by an operator to enable the operator to keep a desired working position of the working machine while regulating power of the engine.
The operation control lever unit includes a handle case having a grip for being gripped by a hand of the operator, a throttle lever pivotally mounted to the handle case and arranged to be manipulated by depression with or releasing from at least one finger excluding the thumb of the operator's hand to regulate rotational speed of the engine while the grip of the handle case is being gripped by the operator's hand, and a brake release lever pivotally mounted to the handle case in diametrically opposite relation to the throttle lever such that the brake release lever can be depressed with a palm of the operator's hand to release the brake mechanism while the grip of the handle case is being gripped by the operator's hand.
Because of the throttle lever and the brake release lever being disposed in diametrically opposite relation, the operator can separately manipulate these two levers merely by adjusting depressing forces or pressures exerted on the respective levers from a finger and a part of the palm (for example, a ball of the thumb) while maintaining a grip on the grip of the handle case.
In one preferred form of the invention, the throttle lever is disposed on one side of the handle case which faces the working tool, and the brake release lever is disposed on the other side of the handle case which faces the engine.
The operation control lever unit may further include a throttle lever arresting mechanism disposed inside the handle case and is operative, in response to pivotal movement of the brake release lever when depressed, to exert a load on the throttle lever to hinder pivotal movement of the throttle lever. With this arresting mechanism, the operator is permitted to release the throttle lever at a desired position while keeping the brake release lever depressed by part of his palm. This operation improves the working efficiency of the engine-powered working machine.
Preferably, the throttle lever is equipped with a throttle return lever manipulable to forcibly return the throttle lever in a direction to decrease rotational speed of the engine. The throttle return lever, when used in combination with the throttle lever arresting mechanism, enables a fine adjustment of the position of the throttle lever.
The throttle lever arresting mechanism may include a throttle lever stop releasably engaged with the throttle lever to keep the throttle lever in an idling position. The throttle lever stop is disengaged from the throttle lever when the brake release lever is depressed to release the brake mechanism. This arrangement enables the operator to start the engine without paying attention to the position of the throttle lever.
The throttle lever may have an integral arm disposed inside the handle case and having a throttle-wire anchoring portion connected to one end of a throttle wire which is connected at the other end thereof to a thr
Higashi Kenji
Hiratsuna Kenjiro
Ikeda Takashi
Kojima Atsushi
Miyazaki Atsushi
Adams & Wilks
Honda Giken Kogyo Kabushiki Kaisha
Payer Hwei-Siu
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