JP2000161589A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing device adopting a piping route such as a mountain-crossing piping and improving the bearing performance in the bearing device of external cooling type. SOLUTION: This bearing device is provided with a bearing 102 supporting a rotary shaft 101, a bearing oil tank 103 storing lubricating oil lubricating the bearing 102, a cooler 108 for cooling the lubricating oil installed outside the oil tank 103, an oil circulation pipe 104 connecting the cooler 108 to the bearing oil tank 103, and a pump 107 installed in the midway between the cooler 108 and the bearing oil tank 103 and circulating the lubricating oil. The device is also provided with a vapor-liquid separator 105 separating the bubble contained in the lubricating oil and a gas removal device 106 removing the gas separated by the vapor-liquid separator 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device such as a radial bearing or a thrust bearing for supporting a rotating shaft of a general rotary machine, and more particularly to a bearing device suitable for use in a system for externally cooling lubricating oil. .

[0002]

2. Description of the Related Art Conventionally, in industrial rotary machines,
In particular, when the machine is large, a plain bearing using lubricating oil is generally widely used as a thrust bearing or a radial bearing. A plain bearing forms an oil film between a bearing surface and a rotary shaft journal, performs normal lubrication, and can support a radial or axial bearing load. For example, in a vertical axis hydraulic machine for pumped-storage power generation, one radial bearing is generally used for a pump turbine, and two radial bearings and one thrust bearing are generally used for a generator motor.

In these bearing devices, as a system for cooling the bearing and the lubricating oil for lubricating and cooling the bearing, an internal cooling system for directly cooling the lubricating oil in the oil tank and a cooler outside the oil tank are provided. And an external cooling system in which the oil tank and the cooler are connected by a pipe. Recently, with the increase in speed and density of rotating machines, an external cooling system in which a cooler is installed outside and an oil tank can be made smaller has been increasingly used.

[0004]

However, in the case of employing the external cooling system, a pipe for circulating the lubricating oil in the lubricating oil tank to the external cooler is required. In the vicinity, the space is limited due to the relationship with other components, and the installation space for the oil circulation pipe is often not available. In such a case, it is often necessary to connect the circulation pump and the cooler through a route that raises the pipe once and then returns the pipe downward. However, if a pipe for performing oil circulation is set up once and then lowered (hereinafter, referred to as “hill-crossing pipe”), the pipe tends to pass a level higher than the free surface in the oil tank. is there. As a result, in the lubricating oil circulating in the piping,
Since a large amount of air bubbles contained in the bearing oil tank is contained, the air bubbles are separated during transportation in the pipe, and in the pipe over the mountain, the air bubbles stay at a high level in the pipe, that is, at the top of the pipe over the mountain. Become. When the air layer stays in the pipe, a phenomenon occurs in which the flow path in the pipe is restricted and the flow rate changes. When the flow rate changes, the cooling capacity of the cooler changes, so that the oil temperature in the oil tank and the bearing temperature are not constant. Therefore, a problem that the bearing performance is reduced occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bearing device of an external cooling type, in which a piping route such as a pipe crossing a mountain can be adopted, and the bearing performance is improved.

[0006]

(1) In order to achieve the above object, the present invention provides a bearing for supporting a rotating shaft, a bearing oil tank for storing lubricating oil for lubricating the bearing, and an external part of the oil tank. A cooler for cooling the lubricating oil installed in the oil cooler, a pipe for oil circulation connecting the cooler to the bearing oil tank, and a pipe installed between the cooler and the bearing oil tank to circulate the lubricating oil. And a bearing device having a pump of
A gas-liquid separator installed in the middle of the pipe for separating air bubbles contained in the lubricating oil, and a gas remover for removing gas separated by the gas-liquid separator are provided. With this configuration, even when there is a pipe over a mountain, the influence of bubbles in the lubricating oil is removed, and a piping route such as a pipe over a mountain can be adopted, and the bearing performance can be improved.

(2) In the above (1), preferably,
The pipe has a peak-over pipe section in the middle thereof, and the gas-liquid separation device is installed in the pipe between the lubricating oil discharge side of the lubricating oil tank and the peak-over pipe section.

(3) In the above (1), preferably,
The flow rate of the lubricating oil flowing in the pipe is set to 1 m / s or more.

(4) In the above (3), preferably,
The flow rate of the lubricating oil flowing in the pipe is set to 2 m / s or more.

(5) In the above (1), preferably,
The pump is a circulating pump having a built-in gas-liquid separation mechanism for separating bubbles contained in lubricating oil, and uses a vacuum pump as the gas removing device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a bearing device according to an embodiment of the present invention will be described below with reference to FIG. FIG.
1 is a block diagram illustrating a configuration of a bearing device according to an embodiment of the present invention.

The bearing device of the external circulation cooling system for lubricating oil according to the present embodiment includes a bearing 102 for supporting a load applied to a rotating shaft 101, and an oil tank 103 for storing lubricating oil for lubricating the bearing. ing.

Since the lubricating oil of the bearing is heated by the bearing 102 to support the load on the rotating shaft, the temperature of the entire oil tank 103 also increases. Therefore, in order to cool the heated lubricating oil, a cooler 108 for cooling the lubricating oil, which is installed outside the oil tank 103, and a lubricating oil, which is installed in the middle of the pipe between the cooler 108 and the oil tank 103 of the bearing, And a pump 107 for circulating water. Cooler 108 and pump 1
07 is the oil tank 10 of the bearing by the oil circulation pipe 104.
3 is connected.

Here, the lubricating oil in the oil tank 103 generates a swirling flow due to the rotation of the rotating shaft 101, whereby bubbles are mixed in from the free surface of the lubricating oil. As for the bubble content, the higher the peripheral speed, the stronger the swirling flow, and the more bubbles are mixed.

On the other hand, in the vicinity of the installation location of the pump-turbine-side radial bearing in which the rotation shaft 101 is the rotation shaft of the pump-turbine, the space is limited due to other components, and the installation space for the oil circulation piping is limited. Often cannot get. Therefore,
For example, if there is an obstacle 110 as shown in the installation space of the pipe, in order to avoid the obstacle 110, a piping route that raises the pipe once and then returns it to the bottom must be taken. No longer. As a result, piping 1
In the middle of 04, there is a mountain-crossing pipe portion 104A. At this time, there is a case where the level of the over-mounting pipe portion 104A becomes higher than the free surface of the lubricating oil in the oil tank 103 (usually a position higher than the upper end of the bearing 102) (for example, the height H in the drawing). In such a case, since a large amount of bubbles contained in the bearing oil tank 103 are contained in the lubricating oil circulating in the pipe 104, the bubbles are separated during transfer in the pipe 104, and the bubbles are separated in the mountain-crossing pipe section 104A. Air bubbles will stay at the top. When the air layer stays in the pipe, the flow path in the pipe is narrowed, the flow rate changes, and the cooling capacity of the cooler changes.

In order to solve such a problem, in the present embodiment, a gas-liquid separation device 105 for separating bubbles contained in the lubricating oil is provided in the middle of the pipe 104, and a gas separated by the gas-liquid separation device 105. And a gas removing device 106 for removing the gas. The lubricating oil that is heated in the lubricating oil tank 103 and contains air bubbles is pumped by the pump 107.
And introduced into the gas-liquid separation device 105. The gas-liquid separation device 105 separates air bubbles from the lubricating oil in which the air bubbles are mixed, and passes the lubricating oil in which the air bubbles are separated from the lubricating oil to the piping section 104A.
Send in the direction. The gas component separated by the gas-liquid separation device 105 is released into the atmosphere removed by the gas removal device 106. The lubricating oil from which the bubbles have been separated is sucked and discharged by the pump 107 and cooled by the cooler 108. The cooled lubricating oil is returned to the lubricating oil tank 103, and cools the lubricating oil in the lubricating oil tank 103.

In this embodiment, the gas-liquid separator 105 is connected to the lubricating oil discharge port of the lubricating oil tank 103 and the pipe 10.
4 is installed between the over-mounting pipe sections 104A. Therefore, since the lubricating oil from which the bubbles are removed is passed through the mountain-crossing pipe portion 104A, the bubbles do not stay at the upper portion, and the flow path in the pipe 104 is not restricted. is there. Therefore, since the flow rate of the lubricating oil does not change, the cooling capacity of the cooler does not change. As a result, the performance of the bearing does not decrease even if the pipe over the mountain is used.

Further, in the present embodiment, the piping 10
The flow rate of the lubricating oil and the diameter of the pipe are set so that the flow velocity of the lubricating oil flowing through the pipe 4 is 1 m / s or more. For example, when the flow rate is 400 L / m, the diameter of the pipe 104 is 6
By setting it to 5φ, the flow velocity of the lubricating oil becomes 2 m / s.

An experimental study was conducted on the relationship between the behavior of air bubbles in lubricating oil containing air bubbles flowing in a horizontal pipe and the flow velocity of the lubricating oil. When the flow velocity was high, the state of the lubricating oil became entirely cloudy. I was In the state of bubbles, small bubbles flow near the center of the pipe, and large bubbles flow near the upper part of the pipe. The speed of the bubbles was substantially equal to the flow rate of the lubricating oil, regardless of the size of the bubbles. On the other hand, when the flow velocity decreases, the state of the lubricating oil has almost disappeared. As for the state of the bubbles, the large bubbles and the small bubbles flowed near the upper part of the pipe while being mixed, and the large bubbles and the small bubbles merged with each other and flowed while growing into large bubbles. The velocity of the bubbles was large and small, both of which were slower than the flow rate of the lubricating oil and were non-uniform.

As a result of examining the behavior of the bubbles while changing the flow velocity, if the flow velocity is 1 m / s or more, the mixture of the bubbles is small, the flow velocity of the lubricating oil is almost equal to the flow velocity of the bubbles, It was found that it was difficult to stay inside.
In particular, if there is a portion such as a pipe crossing a mountain, air bubbles are likely to stay, and in such a case, the flow rate of the lubricating oil is reduced by 1 m.
/ S or more was found to be effective. Desirably, by setting the flow rate of the lubricating oil to 2 m / s or more, large and small bubbles are not mixed at all, and
Large bubbles are unlikely to be generated.Furthermore, large bubbles flow near the top of the pipe, and small bubbles flow near the center of the pipe. found. As a result, even if there is a portion where bubbles are likely to accumulate, such as the mountain crossing pipe portion 104A,
Since the bubbles do not grow, the bubbles hardly accumulate.

Therefore, in the present embodiment, the flow rate of the lubricating oil and the diameter of the pipe are set so that the flow rate of the lubricating oil is 1 m / s or more, preferably 2 m / s or more.

In the above description, the pump 107,
The gas-liquid separation device 105 and the gas-liquid separation device 105 are configured independently of each other. For example, by using a circulating pump having a built-in gas-liquid separation mechanism for separating bubbles contained in lubricating oil as a pump, Can be simplified. At this time, a vacuum pump can be used as the gas removing device 106 for removing the separated gas. Thereby, the circulation of the lubricating oil and the separation and removal of the air bubbles from the lubricating oil can be performed by the two pumps, which is particularly effective when the installation space is limited.

As the circulating pump, a sub-pump chamber is provided at the center of the back pressure side of the main pump impeller, and a centrifugal pump impeller for drawing out a cavity at the center of the impeller is disposed as a sub-pump in the sub-pump chamber. It has a pipeline that releases the discharge pressure to the suction side of the main pump, and has a structure in which an exhaust passage is provided from near the center of the sub-pump impeller to the outside. When the main impeller and the sub-impeller rotate, the air bubbles mixed into the lubricating oil are separated into oil and air by the centrifugal action of the main pump and the sub-pump, and the separated air is guided to an exhaust passage. Since the inside of the exhaust passage becomes a negative pressure portion of the centrifugal pump, by connecting to a vacuum pump and sucking air, gas-liquid separation and air removal can be continuously performed.

By providing a circulation pump and a vacuum pump together,
Since the vacuum pump sucks air from the negative pressure section at the center of the centrifugal pump impeller, the suction capacity as a circulation pump is significantly higher than a simple centrifugal pump. Reliable suction can be ensured even if the pipe goes over a mountain passing through a level higher than the oil level in the oil tank.

Further, since the bubbles can be removed, the bubbles do not collect and become air pockets and stay in the pipe, so that a constant circulation flow rate can be maintained. In particular, for bearing devices, it is necessary to maintain constant bearing temperature, oil temperature, etc. in a steady state in order to secure bearing performance and maintain durability, so it is essential to ensure reliable suction and a constant circulation flow rate. is there.

As described above, according to the present embodiment, even when the piping for circulating the lubricating oil of the bearing is the route of the hill-crossing pipe that passes through a level higher than the oil level in the bearing oil tank, the lubricating oil is mixed in the bearing oil tank. There is no change in the flow rate of the lubricating oil due to the stagnation of air bubbles, and a constant amount of oil can be circulated, and the lubricating oil temperature and the bearing temperature can be kept constant.

In addition, since the piping for circulating the lubricating oil of the bearing can be a pipe of a traversing route that passes a higher level than the oil level in the bearing oil tank, the restriction on the installation location of the lubricating oil circulation pump and the cooler is eased. Thus, the degree of freedom can be increased in the design of the civil engineering structure of the equipment installation building, the equipment layout design in the building, and the like.

Further, since bubbles in the lubricating oil are removed at the same time, especially for a bearing having a high peripheral speed and a large bearing loss, deterioration of the bearing performance due to the inclusion of bubbles is reduced.

[0029]

According to the present invention, in an external cooling type bearing device, a piping route such as a pipe over a mountain can be adopted.
In addition, bearing performance can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a bearing device according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Rotating shaft 102 ... Bearing 103 ... Bearing oil tank 104 ... Oil circulation pipe 104A ... Mountain crossing piping part 105 ... Gas-liquid separation device 106 ... Gas removal device 107 ... Oil circulation pump 108 ... Cooling device 110 ... Obstacle

Claims (5)

[Claims] 1. A bearing for supporting a rotating shaft, a bearing oil tank for storing lubricating oil for lubricating the bearing, a cooler for cooling a lubricating oil installed outside the oil tank, and the cooler and the bearing oil tank. In a bearing device having an oil circulation pipe to be connected and a pump for circulating lubricating oil installed in the middle of the pipe between the cooler and the bearing oil tank, the lubricating oil is installed in the middle of the pipe. A bearing device comprising: a gas-liquid separation device for separating bubbles contained in the gas; and a gas removal device for removing gas separated by the gas-liquid separation device. 2. The bearing device according to claim 1, wherein the pipe has a hill-crossing pipe portion in the middle thereof, and the gas-liquid separation device includes a lubricating oil discharge side of the lubricating oil tank and the hill-crossing pipe section. A bearing device installed in piping between the bearings. 3. The bearing device according to claim 1, wherein the flow velocity of the lubricating oil flowing in the pipe is 1 m / s or more. 4. The bearing device according to claim 3, wherein the flow velocity of the lubricating oil flowing in the pipe is 2 m / s or more. 5. The bearing device according to claim 1, wherein the pump is a circulating pump having a built-in gas-liquid separation mechanism for separating bubbles contained in the lubricating oil, and a vacuum pump is used as the gas removing device. A bearing device characterized by using: