JPS6042326B2 - Thrust protection device for rotating shaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thrust protection device for a rotating shaft that issues an alarm and stops rotation when wear or damage occurs to a thrust bearing.

For example, in a steam turbine, if the thrust bearing supporting the rotor is abnormally worn or damaged, there is a risk that the rotor will move laterally and cause serious damage. The thrust protection device is installed close to the thrust collar near the thrust bearing, and when the thrust bearing wears out or is damaged, it issues an alarm and simultaneously trips the turbine to reduce the thrust force. This prevents serious damage to the blades and nozzles inside the turbine. A conventionally used thrust protection device is shown in FIG. There is a device that converts the movement of the thrust collar into a change in oil pressure, and operates when this oil pressure decreases. The configuration is such that a detection fitting a is fixed to a thrust bearing i that holds a thrust bearing, and a lubricating oil jet nozzle that opens close to the side of a thrust collar j extending from the rotor is attached to the detection fitting a. to be established. Lubricating oil is supplied from passage d through orifice c. A pressure slot e branches off from the passage d to derive the hydraulic pressure between the orifice c and the nozzle, and a pressure switch f and a pressure gauge g are connected thereto. Let Y be the gap between the nozzle ejection port and the thrust collar j. The jetting flow of lubricating oil jetted out from the nozzle is obstructed by the thrust collar j facing across the gap Y, and the corresponding resistance is guided to the pressure groove hole e as back pressure of the nozzle.

The smaller Y is, the greater this back pressure becomes. When the thrust bearing wears out, thrust collar j moves by that amount, and Y
increases. As a result, the amount of flow from the nozzle increases, and the pressure derived from the pressure slot e decreases, causing the pressure switch f to decrease.
operates and the turbine trips. The relationship between gap Y and oil pressure is shown in Figure 2.

This lubricating oil is the same as that supplied to the bearings, and the oil pressure is approximately 91d/1.

The change in oil pressure when the thrust collar j catches the slight movement and trips is about 91c in O.3. Therefore, setting the pressure switch f is difficult and requires high accuracy. However, in this device, there is always a risk of tripping or non-operation due to a differential, set misalignment, or oil pressure fluctuation of the pressure switch f. Turbines have control oil used in the control system, but the main oil pump is used during normal operation, and the electric auxiliary pump is used during operation, which causes large changes in oil pressure. There is also a risk of malfunction depending on the use. That is, with this conventional thrust protection device, the amount of change in oil pressure detected is small due to its construction, and this has resulted in the drawback that it is not reliable enough as a protection device. The present invention improves this and will be described in detail below by illustrating thrust protection of a turbine with reference to FIG. 3 and subsequent figures.

The turbine rotor 1 is rotatably supported by a bearing member 2 via a bearing 3, and at the same time, a thrust bearing 5 is interposed between the turbine rotor 1 and a thrust collar 4.

The thrust bearing 5 is held by a thrust bearing 6 extending from the bearing member 2. A detection fitting 7 is provided protruding from the side surface of the thrust receiver 6. This detection fitting 7 has an L-shape that extends beyond the outer periphery of the thrust collar 4 and faces the outer surface 4''.
″, a slit 8 that becomes a part of the cylinder concentric with the rotor axis
An oil hole 9 is provided which intersects at right angles to the . Control oil is introduced from one end 9'' of the oil hole 9, and a pressure gauge 10 is installed at the other end 9'' on the outlet side.
Connect the pressure switch 11. A partition ring 12 made of a thin plate is fixed to the outer periphery of the thrust collar 4, and one edge 12'' of the partition ring 12 enters into the slit 8.

Circumferential slit holes 13, 13 are provided in one side edge 12''. When the thrust bearing 5 is normal and the thrust collar 4 is in the normal position, the slit holes 13, 13
The oil hole 9 and the oil hole 9 are located at positions shifted in the axial direction, and the oil hole 9 is closed by the partition cylinder 12. Let Z be the gap between them. Next, the operation will be described. Since the oil hole 9 is in a closed state during normal operation, the control oil pressure hardly acts on the pressure gauge 10 and the pressure switch 11.

When the thrust bearing 5 wears out, the thrust collar 4 and the partition ring 12 move in the axial direction, and when the amount of movement exceeds the distance Z, the oil hole 9 and the slit hole 13 begin to overlap, and the oil hole 9 becomes a through hole. The control oil pressure is guided to a pressure gauge 10 and a pressure switch 11. FIG. 7 shows the relationship between the amount of wear of the thrust bearing and the oil pressure. At the point where the amount of wear exceeds the interval Z and the oil hole 9 and the slit hole 13 begin to overlap, the oil pressure increases rapidly.Since the control oil normally uses a hydraulic pressure of about 14k91cILy, the change in the oil pressure in this case is large and increases rapidly. become. This change in oil pressure causes the pressure switch 11 to operate, issue an alarm, and trip the turbine. In this case, the pressure switch 11 operates very sensitively, and the width of the set value cannot be increased. can. Therefore, the differential of the pressure switch 11,
It is possible to prevent misoperation due to misalignment of the set or large fluctuations in the control oil, and there is no risk of malfunction. In this way, it is possible to reliably reach the ultimate goal of stopping the turbine as soon as the wear of the thrust bearing exceeds a certain set value Z, thereby preventing serious damage from occurring. What is shown in Figures 8 and 9 is
In the case of both thrusts, the slit holes 13, 13'' of the partition ring 12 are arranged in two rows, and the oil hole 9 is located between them, and the spacing between them is set at Z, Z''. However, due to wear of the thrust bearing, etc., the thrust collar 4
moves to either side, and either slit hole 13,1
Even if the oil hole 9 overlaps at 3'', the oil pressure guided to the oil pressure switch 11 rises and trips the turbine.

As described above, the present invention obstructs the control oil hole that introduces hydraulic pressure to the pressure switch with a partition ring that is fixed to the shaft and rotates, so that when axial movement occurs due to wear of the thrust bearing, The circumferential slit hole provided in the partition ring and the oil hole overlap to open the oil hole, and the oil pressure to the oil pressure switch suddenly increases and activates the oil pressure switch. Controls trip devices to ensure aircraft safety.

In the mechanism of the present invention, the pressure switch is activated by a sudden increase in the introduced pressure when the set amount of wear is exceeded, and is therefore independent of the magnitude of the control hydraulic pressure. Therefore, there is no need to worry about malfunctions even if the source pressure of the control oil fluctuates, and the set value of the pressure switch can be selected regardless of the source pressure, which is advantageous in terms of accuracy.Moreover, operation is reliable and highly reliable, especially when used with steam. It has features that are highly effective for thrust protection of turbines, etc.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing a conventional steam turbine thrust protection device, Fig. 2 is a chart showing changes in the thrust movement amount and oil pressure, and Fig. 3 is a diagram showing the thrust protection device of the present invention implemented on a steam turbine rotor. Fig. 4 is a longitudinal cross-sectional view of the case shown in Fig. 3A.
- A longitudinal side view taken along line A, Fig. 5 is an enlarged longitudinal sectional view of section B in Fig. 3, Fig. 6 is a perspective view of the partition ring, and Fig. 7 shows changes in the amount of wear and oil pressure of the thrust bearing. 8 is an enlarged vertical cross-sectional view of the main parts in the case of both thrusts, and FIG. 9 is a perspective view of the partition ring. DESCRIPTION OF SYMBOLS 1... Turbine rotor, 2... Bearing member, 3... Bearing, 4... Thrust collar, 5... Thrust bearing, 6 ...Thrust receiver, 7...Detection fitting, 8...Slit, 9...Oil hole, 10...Pressure gauge, 1
1...Pressure switch, 12...Partition ring, 13...Slit hole.

Claims (1)

[Claims] 1. A detection fitting fixed to the thrust bearing for holding the thrust bearing is provided with a slit that forms part of a cylinder concentric with the rotating shaft, and a control oil hole that crosses orthogonally to this slit, while fixed to the rotating shaft. At the same time, at all times, a partition ring with a circumferential slit hole arranged at a position offset in the axial direction from the control oil hole faces into the slit of the detection fitting, and the control oil hole is A rotating shaft thrust protection device characterized by a pressure switch connected to the outlet side.