Excavating – Snow or ice removing or grooming by portable device – Motorized rotary excavating tool
Reexamination Certificate
2001-02-27
2003-04-01
Pezzuto, Robert E. (Department: 3671)
Excavating
Snow or ice removing or grooming by portable device
Motorized rotary excavating tool
C192S01700D
Reexamination Certificate
active
06539649
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to power transmission systems for use in a snow-removing machine for protecting an auger and/or a power delivery path from overload, preventing a decrease in snow-removing performance and allowing the snow-removing machine to be downsized and to be compact in structure.
2. Description of the Related Art
In general, downsized, hand-type self-propelled snow-removing machines have been proposed to transmit output power of an engine to an auger through a power transmission system such that the auger collects snow and collected snow is discharged far off. One of these snow-removing machines is, for example, disclosed in Japanese Utility Model Kokai (Post-Exam) Publication No. 51-34111.
The snow-removing machine of this type usually includes a pulley coupled to an output shaft of an engine, a pulley coupled to a rear end portion of a power delivery path and a belt connected between two pulleys, with a snow blower being located midway of the power delivery path. A forward end of the power delivery path is connected to an auger transmission section that has an auger drive shaft connected to an auger.
For example, during rotation of the auger, when the auger accidentally encounters or hits an obstacle such as compressed snow, a lump of ice or stone projecting upward from a road surface to cause rotation of the auger to be interrupted, the auger, the power delivery path between the auger drive shaft and the engine output shaft, and the engine are caused to encounter excessively large forces.
One technique for protecting the snow-removing machine from excessively large forces is to place a pin, a so-called “shear pin”, in a power delivery path and to cause the shear pin to be cut or broken in overload conditions, prior to the excessively large forces acting on the power delivery path thereby protecting the power delivery path from inadvertent damage.
With such a technology, when the shear pin is cut or broken, however, the snow-removing operation is interrupted, and the damaged shear pin is replaced with new one, resulting in a decrease in the snow-removing performance.
In order to lighten the work load, various attempts have been made to provide a snow-removing machine which is downsized and compact in structure.
In addition, for example, in the event the snow collected by the auger contains an obstacle such as a relatively large stone or a lump of ice, the obstacle accidentally enters a space between the snow blower and the frame body, interrupting rotation of the snow blower such that the snow blower encounters excessively large forces.
In the event the blades of the snow blower encounters damage owing to the excessively large forces, the damaged snow blower must be replaced with new one.
However, in the event the snow blower and the pulley are firmly mounted to the rotational axis, when the blades of the snow blower encounter damage, the snow blower, the rotational axis and the pulley must replaced as a whole, resulting in an increased cost.
Since, further, the aforementioned rotational axis is coupled to the auger transmission section by means of a fastening segment such as bolts, plural fastening segments should be employed in the power delivery path between the engine output shaft and the auger transmission section. Accordingly, when the power delivery path is assembled, the plural fastening segments may cause increased assembling steps, providing deteriorated workability in assembling.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a power transmission system for a snow-removing machine, which system is suitable for preventing a snow blower, an auger and a power delivery path between the auger and a drive source, such as an engine, from excessively large forces, and which system has a simplified mounting structure to allow a damaged snow blower to be easily replaced with a new one, thereby preventing a decrease in snow-removing performance.
According to an aspect of the present invention, there is provided a power transmission system for a snow-removing machine, which system comprises a drive shaft driven by a drive source, an auger transmission for driving an auger located in front of a snow blower driven by the drive shaft, and an overload protecting mechanism connected between the snow blower and the auger transmission for preventing a power delivery path between the drive shaft and the auger transmission from excessive overload.
With the system thus arranged, owing to the overload protecting mechanism located between the auger transmission and the snow blower, it is possible to provide protection from damage when the auger and the power delivery path encounter overload. Also, since the overload protecting mechanism can be located in a large space between the auger transmission and the snow blower, the existing, relatively large space can be effectively utilized thereby allowing the snow-removing machine to be small-sized and compact in structure.
Desirably, the overload protecting mechanism is located in close proximity to the auger transmission. For example, in the event the snow blower is mounted on the main drive shaft with the shear pin for protection of the overload, it is possible to increase the distance between the shear pin and the auger transmission, providing ease of assembling or disassembling of the shear pin.
In a preferred form, the overload protecting mechanism comprises a wet type friction coupling incorporating at least one pair of friction plates held in contact with one another, with one of the friction plates being coupled to the aforementioned main drive shaft while the other friction plate is coupled to the aforementioned auger transmission input shaft. When a torque to be exerted exceeds a given value, the friction plates begin to slip. With such a wet type friction coupling employed as the overload protecting mechanism, the overload to be exerted on the power delivery path is effectively prevented, permitting the complicated assembling step of the shear pin to be omitted while providing improved workability.
Preferably, the input shaft of the auger transmission comprises an oil passage for interconnecting the interior of the auger transmission and the interior of the friction coupling. Flood oil coming out from the friction coupling owing to expansions of various component parts of the friction coupling caused due to thermal heat produced in the friction coupling escapes through the oil passage to the auger transmission, preventing oil from being leaked to outside. Since, further, the auger transmission additionally serves as an oil tank, a specific oil tank is not required for the friction coupling.
It is desirable that the overload protection mechanism further comprises a rubber coupling that includes an input shaft coupled to a main drive shaft, an output shaft coupled to the auger transmission, and cushion rubbers located between the input and output shafts.
Thus, by locating the rubber coupling between the auger transmission and the snow blower, overload is effectively prevented when the auger and the power delivery path encounter overload. Further, it is possible to omit the complicated assembling steps for frequent replacement of the overload protecting shear pin thereby providing an improved workability. In addition, the rubber coupling is located in a large space between the auger transmission and the snow blower, allowing effective utilization of the existing large space while providing the snow-removing machine that is small in size and compact in structure.
The overload protecting mechanism may include input members coupled to the main drive shaft, an output member composed of a cylindrical segment, with the snow blower and the auger transmission being connected to the output member such that the cylindrical member of the overload protecting mechanism is effective to provide protection from damage when the snow blower, the auger and the power delivery path encounter overload, preventing the snow blower. In the preferred emb
Ishikawa Tomoaki
Kobayashi Hiroshi
Sakai Seishu
Sueshige Hiroshi
Yamamoto Takahiro
Adams & Wilks
Honda Giken Kogyo Kabushiki Kaisha
Pezzuto Robert E.
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