JPH04296245A - Speed reducer - Google Patents

Abstract

PURPOSE:To promote the shortening of an output shaft and its eccentric prevention by improving a support structure for the output shaft. CONSTITUTION:A train of reduction gears 4, 5, 6, 7, reducing the rotation of an input shaft 1 and transmitting it to an output shaft 8, is housed in a casing 3. This output shaft 8 is supported on the casing 3 free of rotation by a bearing 9, and a pinion 11 is formed in an end of the output shaft 8 being projected out of the casing 3. An arm 12 leading to the extension direction of the pinion 11 is formed in the casing 3, while an extension axial part 11A is formed in the pinion 11, and the bearing 13 is installed in the arm 12, supporting this extension part 11A.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in reduction gears used in backhoe turning devices and the like.

0002

2. Description of the Related Art A backhoe turning device controls the rotation of a rotating shaft 1 of a hydraulic motor by using a sun gear 4, for example, as shown in FIG.
6 and planet gears 5 and 7, the deceleration is transmitted to the output shaft 8, and the output shaft 8 is connected to the pinion 11.
By driving a rack (not shown) through the rack, a boom connected to the rack is rotated.

0003

The output shaft 8 is rotatably supported by the casing 3 at two locations, a front bearing 13 and a rear bearing 9, and a pinion 11 is formed on the outer periphery of the output shaft 8 protruding outside the casing.

In other words, the pinion 11 is supported in a cantilever structure, and the front bearing 13
The reaction force Rf of the rear bearing 9 and the reaction force Rr of the rear bearing 9 are expressed by the following equation.

[0005] Rf=(L1+L2)×W/L1 Rr
=L2/L1×W In this case, loads equal to Rf and Rr act on the front bearing 13 and rear bearing 9, respectively, so in order to keep these loads within the allowable limits, the distance L1 between the bearings 9 and 13 is It was necessary to set it larger than a certain level.

However, as a result, the output shaft 8 becomes longer and the overall length of the reduction gear becomes longer.

In addition, with this structure, it is necessary to set a large backlash in the meshing of the gears so that abnormal loads are less likely to be applied to the planetary gears when the bearings 9 and 13 are deformed. There was also the problem that gears sometimes collided with each other, creating shocks.

The object of the present invention is to solve the above problems by improving the support structure of the output shaft.

[0009]

[Means for Accomplishing the Objects] The present invention includes a reduction gear that decelerates the rotation of an input shaft and transmits it to the output shaft, which is housed in a casing, and the output shaft is rotatably supported by the casing via a bearing. In a reducer in which a pinion is formed at the end of the output shaft protruding from the casing, an arm extending in the direction of extension of the pinion is formed on the casing, and an extended shaft portion is formed on the pinion, and this extended shaft portion is connected to the arm. It is supported through bearings.

0010

[Operation] By supporting the extended shaft portion of the pinion on the arm using a bearing, pinion support portions are created on both sides of the pinion. Therefore, compared to cantilever support, the load on the bearing is smaller and deformation of the bearing is less likely to occur.

[0011]

Embodiments FIGS. 1 and 2 show embodiments of the present invention.

In this figure, reference numeral 1 denotes a rotating shaft of a hydraulic motor that constitutes an input shaft of a reduction gear. A casing 3 of the reducer is coupled to a body 2 of the hydraulic motor, and a rotating shaft 1 protrudes from the body 2 into the casing 3 so as to be freely rotatable.

Inside the casing 3 are a sun gear 4 spline-coupled to the outer periphery of the rotating shaft 1, a planet gear 5 meshing with the sun gear 4 and revolving around the sun gear 4, a sun gear 6 rotating integrally with the revolution of the planet gear 5, A reduction gear mechanism consisting of a planet gear 7 that meshes with the sun gear 6 and revolves around the sun gear 6 is housed.

An internal gear 10 that guides the revolution of the planet gears 5 and 7 is formed on the inner periphery of the casing 3, and an output shaft 8 that rotates together with the revolution of the planet gear 7 is rotated by the casing 3 by a rear bearing 9. freely supported.

One end of the output shaft 8 projects to the outside of the casing 3, and a pinion 11 is formed on the outer periphery of the projecting end. Furthermore, an extended shaft portion 11A is formed in the pinion 11 in the axial direction.

An arm 12 having a cross-sectional shape shown in FIG. 2 is integrally formed in the casing 3 and extends in the direction of extension of the pinion 11, and a front bearing 13 for supporting the extended shaft portion 11A is provided on the arm 12.

Next, the operation will be explained.

The rotation of the rotating shaft 1 is transmitted to the output shaft 8 while being decelerated through the sun gear 4, planet gear 5, sun gear 6, and planet gear 7, and is transmitted to the output shaft 8 while being decelerated.
Rotate 1.

When the pinion 11 rotates the boom via a rack (not shown), a load W due to the reaction force acts on the pinion 11. This load is front bearing 1
3 and a rear bearing 9. At this time, the reaction forces Rf and Rr of the front bearing 13 and rear bearing 9 are expressed by the following equations.

Rf=WL2/(L1+L2)Rr=WL
1/(L1+L2) As is clear from this equation, Rf and Rr are always smaller than W, so even if the distance (L1+L2) between the front bearing 13 and rear bearing 9 is set short, the load burden on the bearings 9 and 13 is It can be kept small enough.

Therefore, the bearings 9 and 13 are less likely to deform, and even if they are deformed, the eccentricity of the pinion 11 is small.

[0022] Therefore, the overall length of the reduction gear can be shortened, and the backlash of the reduction gear can also be reduced.

[0023]

As described above, in the present invention, the extended shaft formed on the pinion is supported by the arm via a bearing, so the pinion is not supported on a cantilever type, but the pinion is supported on both sides. be done.

Therefore, even if the distance between the bearings is reduced, the load acting on the bearings does not increase, and the overall length of the reducer can be shortened, which is effective in reducing the size and weight of the reducer.

Furthermore, since deformation of the bearing is less likely to occur and eccentricity of the pinion due to deformation is also less likely to occur, it is possible to reduce the backlash of the reduction gear and reduce the shock at the time of starting and stopping.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a speed reducer showing an embodiment of the present invention.

FIG. 2 is a view taken along the line A-A in FIG. 1;

FIG. 3 is a vertical cross-sectional view of a reduction gear showing a conventional example.

[Explanation of symbols]

1 Rotation axis 3 Casing 4,6 Sun gear 5,7 Planet gear 8 Output shaft 9 Rear bearing 11 Pinion 11A Extension shaft part 12 Arm 13 Front bearing

Claims (1)

[Claims] Claim 1: A reduction gear that decelerates the rotation of the input shaft and transmits it to the output shaft is housed in a casing, the output shaft is rotatably supported by the casing via a bearing, and the output shaft projects from the casing. In a speed reducer in which a pinion is formed at the end of the gear, an arm extending in the direction of extension of the pinion is formed on the casing, an extended shaft portion is formed on the pinion, and this extended shaft portion is supported by the arm via a bearing. A speed reducer featuring: