JPS59222638A - Metal fretting preventive device of main bearing in marine auxiliary engine - Google Patents

Abstract

PURPOSE:To reduce a resonance caused between a crankshaft and a generator rotary shaft system so as to prevent metal fretting corrosion from its generation, by mounting a viscous damping oscillation absorber onto a generator rotor shaft coupled to the crankshaft. CONSTITUTION:A viscous damping oscillation absorber 5 comprising a spring 2, damper 4 and a weight 3 is mounted to be formed on a generator rotor shaft 6 between a generator rotor 7 and an exciter 8 which are fixed to the generator rotor shaft 6 coupled to a crankshaft 9 of a marine auxiliary engine. The viscous damping oscillation absorber 5 being mounted in such way decreases a resonance caused between the crankshaft 9 and a generator shaft system and arising from vibromotive force of a main engine when the marine auxiliary engine is stopped, thus substantially reducing vibration of the crankshaft. In this way, the cause of generation of metal fretting corrosion can be removed, and its generation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a main bearing metal fretting prevention device for a marine auxiliary engine that reduces vibration of a crankshaft when the engine is stopped.

When a marine auxiliary engine stops for a long period of time, its main bearing runs out of oil, but when it receives vibration from the main engine under this condition, the crankshaft vibrates within the metal clearance, causing the crankshaft to The bearing metal is struck by
Fretting corrosion, also known as micro-wear, occurs in the bearing metal and crankshaft, which is a major problem that reduces the durability of the engine.

Here, to explain the above-mentioned 7 retting corrosion, it is a case in which minute relative slippage occurs repeatedly at the contact surface of two members integrally connected by crimping, key connection, spline connection, etc. , fretting corrosion is likely to occur on the contact surface, and when this occurs, wear of the contact surface is accelerated, the surface is damaged, and the fatigue strength of the contact member is reduced.

This phenomenon mainly occurs in mechanical parts that vibrate, but it also occurs in the main bearing metal part of the marine auxiliary engine due to vibrations from the main engine in operation while the marine auxiliary engine is stopped.

Therefore, the present invention has been made to solve the above-mentioned conventional problems. The purpose is to reduce the resonance of the generator rotating shaft system and prevent the occurrence of metal fretting corrosion.

That is, the main bearing metal fretting prevention device between marine auxiliary machines of the present invention has a viscous damping motion consisting of a spring, a damper, and a weight on a generator rotating machine shaft connected to a crankshaft between marine auxiliary machines. It is characterized by the installation of a vibration absorber.

First, while the marine auxiliary equipment connected to the generator rotating shaft is stopped, the crankshaft system resonates due to the excitation force of the main engine, and the amplitude increases significantly as shown in diagram A in Figure 1. However, the vibration mode at the time of shaft system resonance takes the form as shown in the diagram in FIG.

In order to avoid such resonance in the shaft system consisting of the crankshaft and the generator rotating shaft, the present invention uses a viscous damping dynamic vibration absorber consisting of a spring, a damper, and a weight on the generator rotating shaft, which has a large amplitude. It has a container attached to it.

This viscous damping dynamic vibration absorber uses a rotating shaft shown in Figure 3, which corresponds to the main vibration system of a dynamic vibration absorber, which is suitable for preventing vibrations with a constant excitation frequency such as those caused by machines that always rotate at a constant speed. 1. A generally viscous damping dynamic vibration absorber such as Utility Model Publication No. 29-2008, in which a Dannoku 4 is added as a damper to the secondary vibration system in addition to the spring 2 and the main body corresponding to the secondary vibration system. 5 is used.

That is, when the engine speed changes as in the main marine engine of the present invention, it is not useful to provide only the spring 2 like a dynamic vibration absorber. Its performance has been improved by adding damping force.

The spring constant of this spring 2 is set so that it does not interfere with normal operation by setting a large spring constant in the radial direction and a small spring constant around the center rotation of the rotating shaft 1. shall be.

Next, FIGS. 4, 5, and 6 are side views of main parts of the crankshaft between marine auxiliary machines and the generator rotating shaft in each embodiment of the present invention, and FIG. Example 1, FIG. 5 shows Example 2, and FIG. 6 shows Example 3, and the same parts in each example are indicated by the same part numbers.

First, in the first embodiment shown in FIG. 4, a generator rotor 7 is fixed on a generator rotating shaft connected to a crankshaft 9 between marine auxiliary machines.
A viscous damping dynamic vibration absorber 5 consisting of a spring 2, a damper 4, and a weight 3 as shown in FIG.

By installing such a viscous damping dynamic vibration absorber 5, the amplitude of the vibration frequency characteristic of the shaft system can be significantly reduced as shown in B in FIG.

Further, in the second embodiment shown in FIG. 5, a viscous damping dynamic vibration absorber 5 having the same structure as above is built into the generator rotor 7, and furthermore, in the third embodiment shown in FIG. It is built inside the generator rotor 7.
and exciter 8, respectively, to reduce the weight of the entire generator.

Therefore, by applying the present invention, it is possible to reduce the resonance of the crankshaft and generator shaft system, which significantly increases crankshaft vibration caused by main engine vibration force when opening and stopping marine auxiliary equipment, which causes fretting corrosion. As a result, crankshaft vibration can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a shaft system vibration frequency characteristic diagram between marine auxiliary equipment, Fig. 2 is a vibration mode during shaft system resonance in Fig. 1, and Fig. 3 is a diagram of a viscous damping dynamic vibration absorber applied to an embodiment of the present invention. Schematic diagram, 4th
5 and 6 are side views of main parts of the crankshaft between marine auxiliaries and the generator rotation shaft in each embodiment of the present invention, and FIG. FIG. 5 shows the second embodiment, and FIG. 6 shows the third embodiment. 1... Rotating shaft, 2... Spring, 6... Weight, 4...
... Damper, 5... Viscous damping dynamic vibration absorber, 6... Generator rotating shaft, 7... Generator rotor, 9... Crankshaft.

Claims (1)

[Claims] A metal frame main bearing for a marine auxiliary engine, characterized in that a viscous damping dynamic vibration absorber consisting of a spring, a damper, and a main body is mounted on a generator rotating shaft connected to the crankshaft of the marine auxiliary engine. Anti-Ting device.