Tool driving or impacting – Impacting devices – Hammer head driven by pulsating fluid pressure
Reexamination Certificate
1999-11-18
2001-12-04
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Impacting devices
Hammer head driven by pulsating fluid pressure
C173S117000, C173S171000, C173S217000
Reexamination Certificate
active
06325157
ABSTRACT:
This application claims priority on Japanese Patent Application No. 10-329887 filed on Nov. 19, 1998, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to striking tools, such as hammer drills and electric power hammer. More particularly, the present invention relates to a striking tool, such as those described above, which cools the motor incorporated therein by generating an airflow through the motor housing.
2. Description of the Related Art
A typical striking tool includes a main housing which contains a striking mechanism with a tool bit attached to the top end thereof and a motor housing which contains a motor and which is connected to a rear portion of the main housing. When the tool is activated, the motor operates the striking mechanism to cause the tool bit to repeatedly strike a workpiece. As the motor generates heat during operation, a cooling fan is generally provided in such a striking tool. Japan Published Unexamined Utility Model Application No. 57-181586 discloses one such tool, in which a cooling fan is fitted around the motor shaft such that rotation of the motor creates an airflow through the motor housing, thus cooling the motor during operation.
Although a conventional arrangement for cooling the motor such as the foregoing serves its purpose, it is not free from certain defects. For example, the airflow created by the fan in the foregoing disclosure does not reach the main housing, passing through the motor housing only. Therefore, heat generated from the cylinder and other elements of the striking mechanism during operation may significantly raise the temperature of the main housing. At times, the operator may find it uncomfortable to hold the tool due to the heat conducted from the striking mechanism.
As a corrective measure, one or more air inlets may be provided on a side portion of the main housing so as to pass air through the main housing. Problems inherent in this arrangement include the ease with which dust or other foreign matter is drawn into the main housing and the adverse effects such foreign matter has on the operation of the striking mechanism when the tool is used with the attached bit pointed upward. While these problems could be solved if the outlets of cooling air are relocated to a side portion of the main housing, other problems are created. For example, unpleasant air would blow against the operator's hand, thus irritating the operator.
SUMMARY OF THE INVENTION
In view of the above-identified problems, an important object of the present invention is to provide a striking tool which can cool the main housing as well as the motor housing while protecting the internal mechanism from dust or any other foreign matter.
Another object of the present invention is to provide a striking tool which can cool the main housing as well as the motor housing while ensuring comfortable use of the tool.
The above objects and other related objects are realized by the invention, which provides a power-driven striking tool having front and rear portions. The striking tool comprises: a main housing containing a striking mechanism for transmitting hammer blows to a tool bit attached to the front portion of the tool; and a motor housing connected behind the main housing. The motor housing contains a motor having a motor shaft on which a fan is provided. When rotated by the motor, the fan creates an airflow through the motor housing. The striking tool further comprises: at least one air inlet provided in the rear of the main housing for admitting the airflow; a closing member extending in front and rear directions for isolating the motor from the main housing; and an air gate configured to allow the airflow to enter the motor housing after passing over a front end of the closing member and through at least a portion of the main housing, thus cooling the striking mechanism.
According to the invention, both the striking mechanism and the motor are cooled by airflow drawn by the motor due to the structure for isolating the motor from the main housing as well as the position of the air inlets. This allows the operator to hold the striking tool without feeling the discomfort caused by excessive heat, thus enhancing the operability of the tool.
According to one aspect of the present invention, the closing structure includes the air gate. In addition, the closing structure can be, for example, a baffle plate including a bottom portion which pneumatically separates the motor housing from the main housing except at the air gate, with the air gate provided in a front end of the bottom portion. In addition, the baffle plate can further include a flange along which the airflow is guided into the main housing toward the air gate.
According to another aspect of the present invention, the motor housing is connected to the main housing such that an axis of the motor housing is oriented at right angles to an axis of the main housing.
According to still another aspect of the present invention, the motor housing contains a substantially cylindrical inner housing for containing the motor, with the inner housing having a substantially circular opening in which the bottom portion of the baffle plate is fitted to close the opening and further the inner housing having a peripheral wall.
According to yet another aspect of the present invention, the flange includes a front end which is distal to the at least one air inlet and proximal to the front portion of the striking tool. In addition, the flange can further include a rear end proximal to the at least one air inlet and distal to the front portion of the striking tool, with the front end being located forward of the air gate such that external air drawn into the tool through the at least one air inlet travels over the flange and around the front end of the baffle plate and enters the motor housing at the air gate.
According to one feature of the present invention, the fan is fitted on the motor shaft in close proximity to a bottom of the motor housing. Additionally, at least one air outlet can be provided in the bottom of the motor housing, such that rotation of the motor draws in external air though the at least one air inlet and discharges the air through the at least one air outlet via the main housing and the motor housing.
According to another feature of the present invention, the inner housing is located intermediately between the front and rear ends of the flange such that the airflow is oriented back toward the at least one inlet as the airflow enters the inner housing.
According to still another feature of the present invention, the striking tool further comprises a handle housing provided in the rear of the main housing and the motor housing, with the at least one air inlet provided in the handle housing directly in the rear of the main housing.
According to yet another feature of the present invention, the baffle plate further includes a recess in which a portion of the striking mechanism is fitted.
According to one practice of the present invention, the air gate is a circular slot concentric with the peripheral wall of the inner housing.
According to another practice of the present invention, the baffle plate further includes an inclined plate extending from a lower edge of the circular slot and reaches the motor housing so as to guide the airflow into the inner housing.
Other general and more specific objects of the invention will in part be obvious and will in part be evident from the drawings and descriptions which follow.
REFERENCES:
patent: 3517755 (1970-06-01), Badcock
patent: 3718193 (1973-02-01), Wanner
patent: 3926266 (1975-12-01), Dorgnon
patent: 4476941 (1984-10-01), Buck et al.
patent: 4567951 (1986-02-01), Fehrle et al.
patent: 5052497 (1991-10-01), Houben et al.
patent: 5099160 (1992-03-01), Strozel et al.
patent: 6123158 (2000-09-01), Steffen
patent: 6127751 (2000-10-01), Kristen et al.
patent: 57-181585 (1981-05-01), None
Arakawa Takuo
Hyodo Koki
Foley Hoag & Eliot LLP
Makita Corporation
Smith Scott A.
LandOfFree
Striking tool with an improved cooling mechanism does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Striking tool with an improved cooling mechanism, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Striking tool with an improved cooling mechanism will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2602576