JPS5829439B2 - Lubricating oil cooling system for water turbine bearings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lubricating oil cooling system for a water turbine bearing that utilizes flowing water flowing through a back pressure chamber above a runner.

Conventionally, oil self-contained bearings for water turbines have two methods: as shown in Figure 1, a cooling pipe 19 is provided in the bearing tank, and the bearing lubricating oil is forcibly cooled by passing cooling water through the pipe, and the water turbine has a low circumferential speed, resulting in less temperature rise. In this case, two methods are used: radiating heat within the bearing tank and cooling it.

That is, in the case of the former forced cooling, since the cooling pipe 19 is installed in the bearing tank of the main shaft 7, it is necessary to provide a large axial distance between the bearing 4 and the metal case 12.

As a result, the distance between the center of the runner 8 and the center of the bearing becomes large, so there is a concern that vibrations may occur, and the cooling pipe 19
Since a constant amount of water must always flow inside the bearing tank, a flow rate relay is used to control the flow rate, and a mixed water relay is used to check if cooling water enters the oil tank due to damage to the cooling pipe in the bearing tank. There are problems in terms of maintenance because it requires installation and thorough management.

The latter can be used for low circumferential speed water turbines, but for medium-high speed water turbines, the temperature rise will be large, so it is necessary to enlarge the oil tank and expand the heat dissipation area.

However, due to structural limitations, it is not possible to provide the necessary heat dissipation area, so in such cases it is often necessary to adopt a forced cooling method.

In order to solve the above-mentioned drawbacks of the conventional technology, the present invention integrates the upper cover and the metal case, cools the bearing lubricating oil by using abundant flowing water flowing through the back pressure chamber at the upper part of the runner, and cools the bearing lubricating oil. The purpose of this invention is to provide a bearing with stable cooling performance by circulating the oil in the oil tank.

The feature of the present invention is that the upper cover and metal case were conventionally separated and integrated with the upper cover by tightening bolts, but now they are integrated by welding, and the surface opposite the back pressure surface of the upper cover is attached to the bottom of the bearing oil tank. The lubricating oil near the bottom of the oil tank is cooled by the pressure water flowing through the back pressure chamber at the top of the runner, and the high-temperature oil flowing from the oil pan into the oil communication pipe with a small drop cools the lubricating oil near the bottom of the oil tank. The volume of the cooled lubricating oil changes and the oil in the oil tank circulates by itself, making it possible to maintain an ideal bearing temperature.

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows an embodiment of a bearing device for a water turbine containing lubricating oil according to the present invention. Oil receivers 2 and 3 are attached to the upper cover 1, and a bearing 4 is attached to the upper cover 1. An oil receiving tray 5 for receiving high-temperature lubricating oil scattered from the oil receiving tray 5 and an oil communication pipe 6 for allowing the oil accumulated in the oil receiving tray 5 to flow down to the bottom of the oil tank are provided.

The oil pan 5 and the oil communication pipe 6 are provided to separate high temperature oil scattered from the bearing sliding surface so that it does not flow down to the upper limit oil level of the bearing oil tank and mix with it.

According to this configuration, sufficient pressure water flowing through the back pressure chamber at the upper part of the runner 8 cools the bearing lubricating oil that is in contact with the surface opposite to the back pressure surface of the upper cover 1, but the lubricating oil in the vicinity of the bottom of the oil tank is cooled. The cooled oil will not move unless it is subjected to some action.

Therefore, the high-temperature lubricating oil scattered from the sliding parts of the bearing 4 and the main shaft 7 is made to flow into the oil pan 5, and the high-temperature oil coming out from the sliding parts is placed on the oil surface of the bearing tank. Make sure it doesn't run off.

The oil flowing into the oil pan 5 flows down into the oil communication pipe 6 with a slight head difference.

The volume of oil inside the oil communication pipe 6 changes, the high temperature oil inside the oil communication pipe 6 is pushed out to the bottom of the bearing oil tank, the volume of the cooled oil at the bottom of the oil tank changes, and the oil communication pipe 6 The oil cooled by the same volume as the volume change of the oil inside 6 will rise.

Therefore, the oil in the bearing oil tank is circulated, and the oil near the outer periphery of the bearing 4 is cooled.

By repeating the above actions, the bearing temperature can be stabilized.

Furthermore, since the water leaking from the sealing box 9 flows through the drain communication pipe 10 and the drain communication pipe 10 is in contact with the oil tank, this water leak also has the effect of further cooling the oil at the bottom of the bearing oil tank.

That is, according to the present invention, the bearing lubricating oil can be cooled without forced cooling, and the cooled oil in the oil tank can be circulated, so that a bearing whose temperature is stable can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of a conventional lubricating oil cooling device for a water turbine bearing, and FIG. 2 is a longitudinal sectional view of a lubricating oil cooling device for a water turbine bearing showing an embodiment of the present invention. 1...Top cover 2...Bearing 1.3.
...Bearing 2.4 ...Bearing, 5 ...
・Oil pan, 6...Oil communication pipe, 7...Main shaft, 8...Runner, 9...Sealing box, 10... Drainage communication pipe.

Claims (1)

[Claims] 1. In a bearing device for a water turbine that contains lubricating oil, an oil tank for lubricating oil is formed by an upper cover provided above the runner, a back pressure chamber is formed between the upper cover and the runner, and A lubricating oil cooling device for a water turbine bearing, characterized in that hot lubricating oil is sent to the bottom of the oil tank, and the upper cover, which forms the bottom of the oil tank, is cooled by running water from a back pressure chamber.