JPS6222005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to a preload adjustment device for tailing pad bearings.

As shown in FIG. 1, a conventional preload adjustment device of this kind has a cylinder 4 installed in a partition wall 3 that separates two fluid chambers having different pressures, namely a high-pressure bearing chamber 1 and a low-pressure back pressure chamber 2. A piston 5 having a built-in preload spring 6 is slidably inserted into the piston 4,
This piston 5 is configured to support a bearing pad 7 that supports a shaft 8. The preload spring 6 is supported by a pedestal 9 attached to the wall 2A of the back pressure chamber 2, and the fluid chamber 2 is communicated with the atmosphere or a low pressure section through a pipe 11 having a valve 10.

In general, if a necessary preload is applied to the bearing in order to obtain stable rotation at high speeds, the torque at startup becomes large, often making startup difficult.

However, the preload adjustment device takes advantage of the fact that the pressure in the bearing chamber 1 is higher than atmospheric pressure, and opens the valve 10 at startup to communicate the back pressure chamber 2 with the atmosphere, thereby acting on the piston 5. Activation can be facilitated by pushing back the preload spring 6 using the fluid pressure difference and reducing the preload on the bearing pad 7. If the valve 10 on the back pressure chamber 2 side is closed after startup, fluid will leak from the bearing chamber 1 to the back pressure chamber 2 through the space between the cylinder 4 and the piston 5, and the pressure balance between both chambers 1 and 2 will be restored. The initial preload due to the spring pressure is regained.

However, with the conventional preload adjustment device mentioned above,
Even if the valve 10 is closed again after opening the back pressure chamber 2, it takes several seconds to several tens of seconds until the pressures in the bearing chamber 1 and the back pressure chamber 2 are balanced. If the rotational speed of the shaft 8 reaches a high speed range during this time, unstable vibrations may occur because the preload has not returned to its normal value. When the vibration is large, there is a risk that the shaft 8 and the bearing 7 may seize before the pressure balance is restored and the preload returns to its normal value and the vibration stabilizes.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a preload adjustment device that can guarantee stable high-speed rotation. In a preload adjustment device for a tailing pad bearing, in which a piston having a built-in preload spring is slidably inserted into the shaft and the bearing pad is supported by the piston, the piston is connected to the two fluid chambers. It is characterized by having holes.

An embodiment of the present invention will be described below with reference to the drawings.

Among the symbols shown in FIG. 2, the same symbols as those shown in FIG. 1 indicate the same parts.

In FIG. 2, 12 is the bearing chamber 1 in the piston 5.
This is a communication hole provided so that the back pressure chamber 2 and the back pressure chamber 2 communicate with each other. If this communication hole 12 is too large, even if the valve 10 is opened to lower the pressure in the back pressure chamber 2,
Since no differential pressure occurs between the bearing chamber 1 and the back pressure chamber 2, it is impossible to push back the force of the spring 6.

Therefore, in order to generate the necessary differential pressure, the cross-sectional area of the communication hole 12 must be made smaller than the value. This value is determined by the volume of the bearing chamber 1 and the back pressure chamber 2 and the pressure difference between the bearing chamber 1 and the outside air, but if the volume of the back pressure chamber 2 is sufficiently small, the diameter of the communication hole 12 is 1 mm or less. A small hole is sufficient. The rest of the structure is the same as the conventional example shown in FIG. 1, so the explanation will be omitted.

Since this embodiment is configured as described above, when the valve 10 provided in the piping 11 communicating with the back pressure chamber 2 is closed, fluid flows from the high pressure bearing chamber 1 to the low pressure back pressure chamber 2 of the piston 5. It flows quickly through the hole 12. As a result, the pressure balance between the two chambers 1 and 2 can be restored instantaneously, so that a normal preload can be applied to the bearing pad 7 via the spring 6.

As explained above, according to the present invention, by instantly restoring the pressure balance between the bearing chamber and the back pressure chamber after the shaft is started, it is possible to apply a regular preload to the bearing. High speed rotation can be guaranteed.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional preload adjustment device, Figure 2 is a sectional view of a conventional preload adjustment device.
The figure is a sectional view showing an embodiment of the preload adjustment device of the present invention. DESCRIPTION OF SYMBOLS 1... Bearing chamber, 2... Back pressure chamber, 4... Cylinder, 5... Piston, 6... Preload spring, 12...
...Communication hole.

Claims (1)

[Claims] 1 On the outer periphery of the first partition defining the high pressure bearing chamber,
A second partition wall defining a low-pressure back pressure chamber is provided, a pipe having a valve for communicating the back pressure chamber with the atmosphere or a low pressure section is connected to the second partition wall, and the second partition wall is connected to the first partition wall. A preload adjustment device for a tailing pad bearing, in which a cylinder is provided, a piston with a built-in preload spring is slidably inserted into the cylinder, and a bearing pad is provided at the end of the piston on the high pressure bearing chamber side. A preload adjustment device characterized in that the piston is provided with a communication hole that communicates a high-pressure bearing chamber and a low-pressure back pressure chamber.