JPH021498Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a bearing cooling water system for a Francis-type hydraulic machine.

[Technical background of the invention and its problems]

In water turbines and pump turbines installed in hydroelectric power plants, during operation, the runners are subjected to a hydraulic unbalance force in the radial direction due to the driving water, which causes shaft runout in the rotating parts including the main shaft directly connected to the runners. occurs. In order to suppress this shaft runout, a bearing device is usually attached to the upper cover to support the main shaft skirt portion from the radial direction.

The bearing device consists of a main bearing, a bearing support, an oil tank, an oil cooling pipe, etc. During main engine operation, friction loss occurs in the lubricating oil film interposed between the main shaft skirt and the main bearing, and this is converted into heat, causing the oil temperature in the oil tank to rise. This lowers the spring stiffness of the lubricating oil film interposed between the main shaft skirt and the main bearing, thereby reducing the performance of the bearing.
Furthermore, as bearing performance deterioration increases, shaft runout increases, and in some cases, the outer peripheral surface of the main shaft skirt and the inner peripheral surface of the main shaft may come into metal contact, and the white metal cast into the inner peripheral surface of the main bearing may be affected by the impact caused by metal contact. It may suffer severe damage such as peeling due to high temperatures.
To avoid such a situation, cooling water is passed through the oil cooling pipe in the oil tank to prevent the oil temperature from rising while the main engine is operating. By the way, cooling water is normally supplied to the oil cooling pipes from a water supply pump installed outside the water turbine pit. In addition, for cooling water drainage, piping from the oil cooling pipe to the drainage pit is necessary, and there is a problem in that the piping is very noisy inside the power plant building.

In particular, in recent years, the effective use of hydraulic resources has been reconsidered, and hydraulic machinery has become more compact, has fewer parts and equipment, and has a simpler structure with an emphasis on ease of maintenance and inspection. Routing the aforementioned piping and securing space for installing the water supply pumps is not easy within the narrow building of the power plant.

Further, in order to supply cooling water to the oil cooling pipe, a device for communicating the back pressure chamber of the runner with the oil cooling pipe and taking water from the back pressure chamber is described in Japanese Utility Model Application No. 58-96063.
This device uses the pressure difference between the atmosphere and the back pressure chamber to draw water into the reservoir, and allows the excess water to overflow from the overflow pipe and pass through the oil cooling pipe.
It is released into the atmosphere. For this reason, the leakage flow rate into the back pressure chamber in the water flow from the speed ring to the runner increases, resulting in a disadvantage that the efficiency of the hydraulic machine decreases.

[Purpose of invention]

An object of the present invention is to provide a bearing cooling device for a hydraulic machine that can prevent a decrease in efficiency of the hydraulic machine and can be cooled with a simple configuration by omitting the cooling water piping disposed in the foundation pit.

[Summary of the idea]

In order to achieve the above object, in the present invention, a main bearing that rotatably guides and supports the main shaft of a hydraulic machine having a Francis-type runner is fixed to an upper cover, and this main bearing is connected to an oil tank with a built-in oil cooling pipe. In the bearing cooling device, the oil cooling pipe is immersed in lubricating oil, and the water supply side of the oil cooling pipe and the back pressure chamber of the runner are connected through a water supply pipe so that cooling water flows into the oil cooling pipe. There is provided a bearing cooling device for a hydraulic machine, characterized in that the drainage side of the pipe and the back pressure chamber of the runner are communicated by a drainage pipe opening into the back pressure chamber inside the water supply pipe.

[Example of idea]

An embodiment of a bearing cooling device according to the present invention will be described below with reference to the drawings.

In FIG. 1, an oil cooling pipe 11 of a main bearing 7 that supports a main shaft 6 is connected from an oil tank 12 to an upper cover 2 via a water supply pipe 10 and a drain pipe 13. The upper cover 2 is provided with a hole that communicates with the back pressure chamber of the Francis-shaped runner 3. The hole that opens into the outer back pressure chamber 14 connects to the water supply pipe 10, and the hole that opens into the inner back pressure chamber 15 connects to the drain pipe. 13, respectively.

Further, FIG. 2 shows a water turbine often seen in small and medium-sized hydroelectric power plants, and an upper cover 2 made of one thick plate is directly attached to the main plate of the speed ring 1. 1st
As shown in the figure, the oil cooling pipe 11 of the main bearing 7 is connected to the water supply pipe 10.
and is connected to the upper cover 2 via a drain pipe 13, and an outer back pressure chamber 14 and an inner back pressure chamber 15, respectively.
The two are connected to each other through a hole made in the upper cover 2.

According to the bearing cooling device configured as described above, the following effects can be obtained.

In Figures 1 and 2, when the main engine is stopped, there is no difference in pressure between the inside and outside back pressure chambers, but during operation, as shown in Figure 3, the inside back pressure P ₂ is higher than the outside back pressure P ₁ . The value is quite low due to the difference in the centrifugal force of the water in the pressure chamber and the effects of the balance hole 3a and the intermediate seal 3b. Furthermore, in the case where there is no intermediate seal 3b, as shown in FIG. 4, there is a considerable difference in runner back pressure between the inner circumference and the outer circumference due to the difference in centrifugal force between the outer and outer circumferences of the back pressure chamber and the effect of the balance hole 3a.

Therefore, due to the difference in these back pressures, the water flowing in the runner back pressure chamber is cooled by oil through the outer back pressure chamber 14 on the high pressure side or the hole made in the bottom plate of the cover above the outer periphery of the back pressure chamber and the water supply pipe 10. The oil flows into the pipe 11, circulates in the oil tank, and then is discharged to the inner back pressure chamber 14 on the low pressure side or to the inner periphery of the back pressure chamber through the drain pipe 13 and the hole in the bottom plate of the upper cover.

Therefore, the piping for the main bearing cooling water only needs to connect the oil tank 12 and the hole provided in the upper cover 2, and there is no need to route piping indoors or into the water turbine pit as in the past. Furthermore, regarding the water supply pump, water sealing device 5 is used since there is no need to supply water to main bearing 7.
A small pump is sufficient to supply water to the pump, and the diameter of the piping connected to the pump and the capacity of the strainer can also be reduced. In power plants where water is supplied to the main bearing 7 using a dedicated pump, the dedicated pump itself becomes unnecessary, making it extremely easy to install other equipment, especially in the narrow buildings of small and medium-sized hydropower plants, and the hydraulic machinery itself. It becomes extremely compact.

[Effect of idea]

As detailed above, according to the present invention, the oil cooling pipe and the back pressure chamber are connected through a drain pipe, and the cooling water supplied from the back pressure chamber is returned to the back pressure chamber, thereby improving the efficiency of the hydraulic machine. The oil tank can be cooled without lowering the oil tank, and the cooling water piping inside the foundation pit can be omitted, which is effective in simplifying the configuration of the Francis type hydraulic machine.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a hydraulic machine showing one embodiment of the present invention, Fig. 2 is a sectional view of a hydraulic machine showing another embodiment, and Fig. 3 is a back pressure chamber pressure in the case of a runner with an intermediate seal. Distribution diagram, FIG. 4 is a back pressure chamber pressure distribution diagram in the case of a runner without an intermediate seal. 2...Top cover, 3...Runner, 6...Main shaft, 7
... Main bearing, 10 ... Water supply pipe, 11 ... Oil cooling pipe, 12 ... Oil tank, 13 ... Drain pipe, 14 ... Outer back pressure chamber, 15 ... Inner back pressure chamber.

Claims (1)

[Scope of utility model registration request] The main bearing, which rotatably guides and supports the main shaft of a hydraulic machine with a Francis-type runner, is fixed to the upper cover, and the main bearing is immersed in lubricating oil in an oil tank containing a built-in oil cooling pipe. In the bearing cooling device, the water supply side and the back pressure chamber of the runner are communicated with each other through a water supply pipe so that cooling water flows into the oil cooling pipe, wherein the water supply side of the oil cooling pipe and the back pressure chamber of the runner are connected to each other. A bearing cooling device for a hydraulic machine, characterized in that the water supply pipe is connected to a back pressure chamber inside the water supply pipe through a drain pipe that opens to the back pressure chamber.