Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Pump and motor in series with planetary gearing
Reexamination Certificate
2001-03-06
2003-11-11
Rodriguez, Pam (Department: 3683)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Pump and motor in series with planetary gearing
C475S031000, C475S346000
Reexamination Certificate
active
06645107
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an epicycle reduction gear or gear arrangement in which a hydraulic motor is built to be used for a drive device of an endless crawler belt or caterpillar band.
For a conventional epicycle reduction gear having a built-in hydraulic motor, Japanese Patent Laid-open Publication No. SHO 59-147154, Japanese Patent Laid-open Publication No. HEI 11-22789 and Japanese Patent Laid-open Publication No. HEI 4-43 disclose a planetary gear carrier structure of the epicycle reduction gear disposed adjacent to a hydraulic motor housing.
In the structure disclosed in the Japanese Patent Laid-open Publication No. SHO 59-147154, an axial external tooth spline is formed to an outer diameter side of an outer end surface of a hydraulic motor housing, and an axial internal tooth spline formed to an outer diameter side of one side carrier of a carrier carrying both ends of a planetary gear shaft of the epicycle reduction gear is meshed with the outer tooth spline mentioned above. According to such structure, the carrier carrying both ends of the planetary gear shaft is formed independently from the hydraulic motor housing and is integrally secured to the hydraulic motor housing.
On the other hand, in the structure disclosed in the Japanese Patent Laid-open Publication No. HEI 11-22789, a carrier carrying both ends of a planetary gear shaft is independently formed from the hydraulic motor housing and is fastened by means of bolts to an outer end surface of the hydraulic housing case so that the carrier carrying both ends of the planetary gear shaft is integrally secured to the hydraulic motor housing case.
Furthermore, in the structure of the Japanese Patent Laid-open Publication No. HEI 4-43, a support shaft (cantilever shaft) supporting one end of a planetary gear of an epicycle reduction gear is formed to an outer end surface of a hydraulic motor housing case so as to project outward therefrom, and a planetary gear is mounted to this support shaft so that the planetary gear is mounted to the outer end side of the hydraulic motor housing case to be rotatable.
Furthermore, in the epicycle reduction gears or gear arrangements disclosed in the above-mentioned Japanese Patent Laid-open Publication No. SHO 59-147154, Japanese Patent Laid-open Publication No. HEI 11-22789 and Japanese Patent Laid-open Publication No. HEI 4-43, needle bearings rolling around planetary gear shafts are utilized as rotation bearings for the planetary gears.
However, in the structure of mounting the carrier carrying both ends of the planetary gear shaft to the hydraulic motor housing disclosed in the Japanese Patent Laid-open Publication No. SHO 59-147154, the outer diameter of the planetary gear carrier is larger than that of the outer end surface of the hydraulic motor housing case, and hence, an outer diameter of a cylindrical drum rotating on an outer peripheral side of the hydraulic motor housing case is inevitably made large. Accordingly, in a case where such reduction gear mechanism as shown in this Japanese Patent Laid-open Publication No. SHO 59-147154 is utilized as a crawler belt drive device for a vehicle, such as bull-dozer traveling at a fast speed, the rotational peripheral speed of the cylindrical drum will be made fast, which may give an adverse influence on a wearing (abrasion) lifetime of a mechanical seal ring disposed between the cylindrical drum and the hydraulic motor housing case for preventing lubrication oil in the reduction gear from leaking and preventing sediment, soil, small stone, and the like from invading inside. In order to obviate such defect, it has been desired to make reduced an outer diameter of the carrier carrying both ends of the planetary gear shaft to thereby reduce the outer diameter of the cylindrical drum.
Furthermore, in the epicycle reduction gears or gear arrangements disclosed in the Japanese Patent Laid-open Publication No. SHO 59-147154 and Japanese Patent Laid-open Publication No. HEI 11-22789, needle bearings rolling around the planetary gear shafts are utilized as rotation bearings for the planetary gears.
However, in such structures, since a surface pressure is directly loaded to the planetary gear shaft, it becomes necessary to use a planetary gear shaft having a large diameter in the viewpoint of durability and/or strength, which results in an enlargement of the outer diameter of the carrier carrying both ends of the planetary gear shaft. And, it becomes necessary to make high a thrust receiving wall section of the needle bearing, thereby, in cooperation of the enlargement of the diameter of the planetary gear shaft, the outer diameter of the carrier carrying both ends of the planetary gear shaft is made further widened. Because of such reasons mentioned above, the outer diameter of the carrier is made larger than the outer diameter of the hydraulic motor housing case, and hence, the outer diameter of the cylindrical drum rotating on the outer peripheral side of the hydraulic motor housing case becomes inevitably large. It is therefore desired to make reduced the outer diameter of the carrier as well as to improve the planetary gear rotation bearing means with respect to the planetary gear shaft.
Still furthermore, as disclosed in the Japanese Patent Laid-open Publication No. HEI 4-43, in the structure that the planetary gear cantilever support shaft of the epicycle reduction gear is formed, in a projecting manner, to the outer end surface of the hydraulic motor housing case, the planetary gear cantilever support shaft does not exceed the outer diameter of the hydraulic motor housing case, so that the outer diameter of the cylindrical drum rotating on the outer peripheral side of the hydraulic motor housing case can be made smaller. However, this structure provides such a problem as that the cantilever support shaft, which is supported at only one side, may be bent, thus being not practical.
Still furthermore, in the structures of the Japanese Patent Laid-open Publication Nos. SHO 59-147154 and HEI 11-22789, since one side thickened portion of the carrier is overlapped to the hydraulic motor housing case, the axial dimensions of the epicycle reduction gear is made long, and in a case where a crawler belt having a narrow width is utilized, there may cause a case that the end edge of the planetary reduction gear extends beyond over the width of the crawler belt and not disposed within this width, so that there is a fear of damaging the epicycle reduction gear having a built-in hydraulic motor, thus providing a problem, which has been desired to be solved by reducing the axial dimension of the epicycle reduction gear or gear arrangement.
SUMMARY OF THE INVENTION
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide an epicycle reduction gear having a built-in hydraulic motor in which a carrier carrying both ends of a planetary gear shaft is monolithically formed to an outer end surface side of the hydraulic motor housing, reducing an outer diameter of the carrier to be less than an inner diameter of a rotation (rotating) bearing of a rotation (rotating) drum.
This and other object can be achieved according to the present invention by providing an epicycle reduction gear having a built-in hydraulic motor in which a rotation drum formed with internal teeth is rotatably attached to an outer peripheral side of a hydraulic motor housing in which a hydraulic motor is housed and a planetary gear is arranged between an output shaft of the hydraulic motor projecting and extending from the hydraulic motor housing and the internal teeth of the rotation drum to thereby rotate the rotation drum in a speed reduced manner,
wherein the hydraulic motor housing is provided with a shell portion to which the rotation drum is fitted through a rotation bearing and a carrier member carrying both ends of a planetary gear shaft and having an outer diameter less than an inner diameter of the rotation bearing is formed monolithically to an outer
Armstrong Westerman & Hattori, LLP.
Komatsu Ltd.
Rodriguez Pam
LandOfFree
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