JPH0735202A - Gear transmission - Google Patents

Abstract

PURPOSE:To realize low vibration and noise of a gear transmission effectively by increasing support rigidity in the radial direction of a bearing which supports a pair of gears. CONSTITUTION:A drive gear 1 and a drive gear shaft 3 of a gear transmission are supported by a drive gear bearing 5 in which a section having higher rigidity in the radial direction than the other sections exists at four places on a periphery of a bearing face, and the drive gear 1 meshes with a driven gear 2 at teeth 7, 8. The driven gear 2 and a driven gear shaft 4 are supported by a driven gear shaft bearing 6 in which a section having higher rigidity in the radial direction than the other sections exists at three places on the periphery of the bearing face. When the gear vibrates in a specific direction greatly, vibration having directivity also occurs in a gear shaft support section. Thus, it is possible to suppress vibration displacement of the gear by increasing support rigidity of the gear shafts 3, 4 in the direction of vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear transmission, and more particularly to a bearing structure for a gear transmission suitable for reducing the generation of vibration and noise.

[0002]

2. Description of the Related Art Most of the noise generated from a gear transmission is solid propagating sound in which a dynamic load generated on a tooth surface propagates through a bearing to a gear box and is radiated as a sound. Therefore, noise can be reduced unless the vibration of the gear shaft is transmitted to the gear box.

One of the methods is, for example, Japanese Patent Publication Sho 52.
As disclosed in Japanese Patent Publication No. 79168, it has been proposed to provide a damping material in a vibration propagation path between a gear and a shaft and between a bearing and a gear box to absorb the vibration. Another method is gear accuracy and performance P124 to P125 (197).
As seen in February 26, 1997, published by Taiga Publishing Co., Ltd., a method of suppressing vibration displacement by increasing the rigidity of a bearing portion has been proposed.

It is considered that these methods are effective in reducing the vibration of the gear box. However, when the vibration of the gear has directionality and vibrates greatly in a specific direction, it is not economical to apply these methods over the entire circumference of the bearing portion.

[0005]

There are always some resonance points in the gear transmission, and vibration and noise become very large at the time of resonance. For this reason, the operating speed of the gear transmission is usually set at the resonance point. However, it may be necessary to operate near the resonance point when the operating speed is changed, or when starting or stopping.

In such a case, the vibration due to the meshing of the gears has a remarkable directivity. Although this direction differs depending on the vibration mode, it can be calculated if the spring stiffness of the bearings and gear teeth is known.

In the conventional gear transmission, the support rigidity of the gear shaft is not increased in a specific direction with respect to the resonance as described above, and when a particularly large vibration occurs in a specific direction, the gear There is a problem that the vibration of the shaft cannot be suppressed sufficiently.

An object of the present invention is to solve the above problems and to provide a gear transmission with less vibration and noise.

[0009]

Since the vibration direction of the gear has directivity, the present invention suppresses the vibration displacement of the gear by increasing the shaft support rigidity in the direction in which the gear vibrates.

[0010]

When the gear vibrates greatly in a specific direction due to resonance or the like, the gear shaft support portion also vibrates with directivity. According to the present invention, the vibration displacement of the gear can be suppressed by increasing the support rigidity of the gear shaft in accordance with the vibration direction.

[0011]

【Example】

(Embodiment 1) FIG. 1 shows a first embodiment of a gear transmission according to the present invention.

In FIG. 1, the drive gear 1 and the drive gear shaft 3 are rotatable about the drive gear shaft, and there are four locations on the circumference of the bearing surface, and portions having higher rigidity in the radial direction than the other portions. It is supported by a drive gear shaft bearing 5 which is characterized by being present. The driving gear has teeth 7 and 8 meshing with the driven gear 2, and the driven gear and the driven gear shaft 4 are rotatable around the driven gear shaft. It is supported by the driven gear shaft bearing 6 which is characterized in that there is a portion having high rigidity in the radial direction.

In the dynamic pressure bearing, the bearing reaction force is obtained by the oil film pressure generated when the rotary shaft draws oil. In a normal bearing whose bearing surface is composed of a perfect circle, there is only one location where this oil film pressure occurs, but in a multi-arc slide bearing, oil film pressure is generated by the number of arcs that make up the bearing surface. The part exists. For this reason, a force that holds the shaft center at the center of the bearing is generated to increase the rigidity of the entire bearing, and a portion where the oil film pressure is generated becomes higher in rigidity than other portions of the bearing surface.

If the direction of vibration of the gear is made to coincide with the portion where the oil film pressure is generated, a fluctuating load is applied at a high oil film pressure, and vibration of the gear shaft can be suppressed. This multi-arc slide bearing is applied to a gear transmission.

In this gear transmission, when the drive gear rotates counterclockwise to transmit power to the driven gear, a fluctuating load due to meshing is generated in the drive gear shaft bearing in the direction of arrow 9. Further, since there is no restraint of the tooth spring, the vibration easily occurs in the direction of the arrow 10 depending on the vibration mode. In order to suppress the vibration displacement in this direction, a four-arc slide bearing having four places on the circumference of the bearing surface and a part having higher rigidity in the radial direction than the other parts is used. And 10 directions.

In addition to the vibration in the direction of arrow 12, the driven gear shaft bearing must receive the transmitted load in the direction of arrow 11. For this reason, a three-arc slide bearing is used, in which there are three locations on the circumference of the bearing surface that have higher rigidity in the radial direction than other portions, and the locations with high rigidity are aligned with the directions of arrows 11 and 12. Let

(Second Embodiment) FIG. 2 shows a second embodiment of the gear transmission according to the present invention.

The gear transmission of FIG. 2 has the same structure as that of the first embodiment, but the drive gear shaft and the driven gear shaft are supported by the hydrostatic bearings 13 and 14. Each hydrostatic bearing has throttles and pockets 15 and 16, and the positions where these throttles and pockets are present have higher support rigidity than the other parts of the bearing.

The high-rigidity portion of the drive-side bearing coincides with the directions of arrows 9 and 10, and the high-rigidity portion of the driven-side bearing coincides with the directions of arrows 11 and 12.

(Embodiment 3) A third embodiment of the gear transmission according to the present invention is shown in FIG.

The gear transmission of FIG. 3 has the same structure as that of the first embodiment, but the driving gear shaft and the driven gear shaft are supported by the rolling bearings 17 and 18. Each rolling bearing has outer rings 19 and 20 characterized in that the raceway surface is not a perfect circle, so that the bearing clearance is smaller at the positions of arrows 9, 10, 11, and 12 than at other parts. Built into the transmission. In this manner, the preload is partially applied to the bearing to increase the bearing rigidity in the specific direction, thereby suppressing the vibration displacement.

[0022]

In the gear transmission according to the present invention, by partially increasing the radial support rigidity of the bearings that support the gear pair, low vibration and low noise of the gear transmission are effectively realized. be able to.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a gear transmission according to the present invention.

FIG. 2 is a front view of an embodiment in which a hydrostatic bearing is used as the bearing.

FIG. 3 is a front view of an embodiment in which a rolling bearing is used as the bearing.

[Explanation of symbols]

1 ... driving gear, 2 ... driven gear, 3 ... driving gear shaft, 4 ... driving gear shaft, 5 ... driving gear shaft bearing, 6 ... driving gear shaft bearing,
7 ... drive gear tooth, 8 ... driven gear tooth, 9, 11 ... acting line direction, 10, 12 ... direction orthogonal to acting line.

Claims (1)

[Claims] 1. A gear transmission comprising at least a pair of gears meshing with each other, a gear shaft, a bearing supporting the gear shaft, and a gear box holding the bearing,
A gear transmission having shaft supporting means for locally increasing the supporting rigidity of a shaft at least at three positions.