JPH0266316A - Thrust-bearing lubricating device - Google Patents

Abstract

PURPOSE: To minimize the total lubricant flow quantity required for both bearings by providing a distributing device for distributing a lubricant to be supplied to a first and a second thrust bearings, and a device for sensing the axial thrust direction. CONSTITUTION: A first and a second thrust bearings 35, 37 for supporting a rotary shaft 31 with a thrust collar 33 are provided with an annular cage supporting a plurality of bearing pads. In a distributing device 41 for distributing to supply lubricant to the bearings 35, 37, lubricating film pressure generated between thrust bearing surfaces and the surface of the thrust collar 33 is monitored by pipes 45, 47, and in response to this, a spool of the distributing device is controlled to control the divided flow quantity. The total lubricant flow quantity required for both bearings can therefore be minimized.

Description

BACKGROUND OF THE INVENTION The present invention relates generally to thrust bearing lubricant supply systems of the type used in large rotary shaft machines, and more particularly to lubricant delivery systems for thrust bearings of the type used in large rotary shaft machines, and in particular for distributing lubricant to either active or inactive bearings. The present invention relates to a device corresponding to an axial thrust.

Rotating shaft machines such as turbines are equipped with stationary thrust bearings that prevent excessive axial movement of the rotating shaft. A rotating shaft rotates with the shaft and has "active" and "inactive"
It has a thrust collar installed between the bearings. Lubricating fluid is directed to both bearings to form a lubricating film on each thrust bearing surface, which film supports the thrust collar as the shaft moves in either axial direction. "Active" thrust bearings are usually expected to support high loads most of the time, while "inactive" bearings support loads part of the time.

The problem to be solved by the present invention is to cope with various operating conditions that normally apply loads to inert bearings,
The objective is to minimize the total lubricant flow to the two thrust bearings.

In the prior art, normal practice in turbomachine thrust bearing design is to size the required normally active bearing based on the expected steady state operating conditions of the machine. The axial thrust acting on various elements of the rotating shaft, including for example the blades, wheel discs, etc., is evaluated and the net axial thrust is determined for this steady state.

Net axial thrust is typically a small difference between two large values that push the axis of rotation forward and backward. It is known to designers that calculations of this net axial thrust are subject to significant errors.

Nevertheless, normally active thrust bearings are generally sized based on a calculation of the net thrust load and the allowable load per square inch of thrust bearing area. The river flow rate for this conventional active bearing is determined from considerations of its size, load, and sliding speed.

In the design of high-load gas turbines, it is common practice to design normally inert bearings that are smaller than normally active bearings based on the assumption that the inert thrust load does not exceed 50% of the design active thrust load. . The size of the passive thrust bearing and the required flow rate are therefore based on this assumption. The total flow to the thrust bearings is provided based on the requirements of the full size active thrust bearings and the lesser capacity of the inactive thrust bearings. A typical thrust bearing lubricant supply system includes a common header that supplies a journal bearing and two thrust bearings. The flow rate to each thrust bearing is controlled by differently sized orifices or perforations in the casting through which lubricant must be supplied from the inlet header.

Design considerations for sizing passive thrust bearings result in the benefit of reduced lubricant flow. However, under certain conditions the lubricant supplied to the passive bearing is inadequate or marginal for a given thrust load. As previously mentioned, net thrust load calculations are inherently erroneous even under mechanical design values. During undesigned machine operation, or during transient machine operation, or due to wear of certain critical elements, normally inert bearings are subjected to high thrusts. In such cases, it is desirable to allow a higher than normal flow rate to flow through the inert bearing.

It is common practice to provide turbomachine rotors with active and inactive thrust bearings. When a turbomachine has active and inactive bearings of the same size, it is common practice to supply lubricant to both bearings at sufficient flow rates.

OBJECTS OF THE INVENTION An object of the invention is to minimize the total lubricant flow required to both thrust bearings, whether they are of the same size or of different sizes. If the two bearings are the same size, the total flow required is the minimum required for a single bearing. If the bearings are not the same size, the total flow required is that required for the larger bearing.

SUMMARY OF THE INVENTION The present invention is implemented in a rotating shaft machine having a shaft-mounted thrust collar located between an active thrust bearing and an inactive thrust bearing. A supply of lubricating fluid is routed to a distribution device that serves as a spool valve. The position of the spool valve is determined by the pilot fluid port, which transmits the shaft position to the distributor, while the position of the spool valve determines the lubricant flow rate through the distribution port of the distributor, and the distributor is activated. and connected to an inert thrust bearing. In this manner, the position of the thrust collar relative to the active and inactive thrust bearings is communicated to the lubricant distribution system, and the appropriate amount of lubricant flows to the thrust bearings as desired.

Detailed description of the invention FIG. 1 shows the inlet end of a rotating machine in cross-section.

The port end 1 is equipped with an annular port 3 which sucks the incoming gas into the machine. Rotor or shaft of rotation 5 with its end shown
is provided with a thrust collar 7 positioned within the machine and fixed to the rotating shaft. Inner casing 9 surrounds the rotor end and generally supports active thrust bearing 11 and inactive thrust bearing 13. Active and inactive thrust bearings are determined generally by the direction of thrust of the working fluid as indicated by arrow 15.

In FIG. 1, active bearing 11 is larger than inactive bearing 15 in order to absorb thrust in the direction of arrow 15.

Bearing lubricant is supplied through lubricant supply pipe 19 and
1 to the active bearing 11 , through the tube 23 to the inactive bearing 13 , and through the tube 25 to the journal bearing 27 . Each supply tube 21.23 or 25 is differently sized or equipped with a differently sized flow restrictor so as to supply the appropriate amount of lubricating fluid to each bearing.

FIG. 2 shows a thrust bearing lubrication system 30 according to the present invention. A rotary shaft 31 of a rotary shaft machine (not shown) has a thrust collar 33 which is made integral with the rotary shaft for rotation therewith.

Although the active and inactive or first and second thrust bearings 35 and 37 respectively surround the axis of rotation and are shown to be of the same size as shown, they are different in that the active bearing is larger than the inactive bearing. Can be dimensioned. Thrust bearing constructions are well known in the art and thus need not be further described, but each bearing differs in that it generally includes an annular cage supporting a plurality of bearing pads. The bearing itself is thus an annular structure consisting of a number of arcuate segments or bearing pads.

The thrust bearing lubrication system of the present invention includes a device 41 for distributing lubricating fluid and further has an input bearing lubrication fluid indicated by arrow 43. The device 41 for distributing lubricating fluid basically comprises a manifold with inputs and outputs as described below. Assuming that the thrust direction in Figure 2 is the same as in Figure 1, i.e. from right to left, the active thrust bearing is bearing 35.
, and the inactive thrust bearing is bearing 37. Each thrust bearing develops a respective bearing lubricating film pressure between the thrust bearing surface and the thrust collar surface. The fluid film in the active thrust bearing is thus monitored by on the tube 45,
The fluid film pressure in the inert thrust bearing is monitored by tube 47, and both produce a type of feedback or control signal to the lubricating fluid distribution device 41, as indicated by the arrow, to sense the direction and position of the axial thrust. Form the device. Also, discharge fluid distribution pipes 49 and 51
are provided which couple the fluid distribution device 41 to the active bearing 35 and the inactive bearing 37, respectively.

FIG. 3 shows a cross-sectional view of the fluid distribution device 41, and in particular shows the slidable spool valve 55 in the fluid distribution device.

Fluid distribution device 41 further has first and second fluid distribution ports 59 and 61 that communicate with active and inactive effluent fluid distribution lines 49 and 51, respectively. Fluid distribution device 41 further includes first and second distribution pilot ports 65 and 67 that communicate with inlet active pressure tube 45 and inactive pressure tube 47, respectively.

FIG. 5 shows pressure distribution curves between active and inactive bearings 35 and 37 for active bearing surface 75 of thrust collar 33 and inactive bearing surface 77 of thrust collar 33, respectively. It can be seen from the inert pressure distribution diagram 81 that the closer the thrust collar is to the bearing, the greater the pressure sensed within the tube 47. Similarly, as shown in pressure diagram 83, the further the bearing is from the thrust collar, the less pressure will be sensed by the conventional active tube 45.

In FIG. 4, the total flow 43 in the lubricating fluid distribution device (manifold) is distributed as a result of the pressure sensed at each bearing, which pressure depends on the axial position of the thrust collar and thus the rotor itself. According to FIG. 5, the rotor moves toward the inert bearing, thereby increasing the fluid pressure in the tube 47 that connects to the pilot pressure cupboard lower.

The increased pressure drives spool valve 55 to the left as shown, opening fluid distribution port 61 and allowing a greater portion of the total fluid flow ff 143 to flow into fluid distribution line 51.

The foregoing is accomplished by pressure support on the two-sided piston 90, creating a resultant force in one or the other direction, and then plugs 95 and 9 extending in opposite directions from the piston.
7 to open either the active fluid distribution port 59 or the inert fluid distribution port 61.

Further in accordance with the present invention, if the two thrust bearings are of the same size, the total lubricant flow rate 43 distributed is equal to the maximum expected flow rate for one bearing.

If the two bearings are not the same size, the total lubricant flow distributed f; 143 is equal to the maximum flow expected for the large bearing.

Although what are considered to be preferred embodiments of the invention have been described above, it should be noted that other embodiments will occur to those skilled in the art. For example, in addition to sensing pressure, similar methods exist for determining the position of thrust collars relative to bearing surfaces, using electronic load cells to including generating a positioning signal to the valve. The claims are intended to cover such modifications as fall within the true spirit and scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional front view of the rotating machine, generally in the area of the thrust bearing. FIG. 2 is a route diagram of the present invention in combination with a thrust bearing. FIG. 3 is a cross-sectional view of a spool valve used in the dispensing device of the present invention when the valve is in a neutral position. FIG. 4 is a cross-sectional view of a spool valve used in the distribution device of the present invention when the valve diverts more flow to one bearing than the other. FIG. 5 is a load diagram showing the direction of the generated force used to determine the position of the rotating shaft. Explanation of main symbols 30... Lubricating device, 31... Rotating shaft, 33... Thrust collar, 35. 37... First. Second thrust bearing, 41... Distribution device, 55... Spool valve, 59
．． 61...1st. 2nd distribution port, 65.67...
1st. 2nd pilot port, 90... piston, 9
5,97...1st. 2nd plug

Claims (1)

[Claims] 1. A rotating shaft having a thrust collar that can rotate together, a first thrust bearing on one side of the thrust collar and a second thrust bearing on the other side of the thrust collar, and for the thrust bearing. A thrust bearing lubrication device for a machine comprising a lubricant supply device, comprising: a device for distributing lubricant to either the first or second thrust bearing according to the direction of axial thrust. 2. The thrust bearing lubrication system of claim 1, further comprising a device communicating with the distribution device and sensing the direction of axial thrust of the shaft. 3. The distribution device includes a spool valve having first and second fluid distribution ports and first and second pilot fluid ports, the spool valve having two surfaces slidable between the first and second pilot ports. The thrust bearing lubricating device according to claim 1, further comprising a piston. 4. The device for sensing the direction of axial thrust comprises a first fluid pipe between the first thrust bearing and the distribution device and a second fluid pipe between the second thrust bearing and the distribution device. The thrust bearing lubricating device according to item 1. 5. The distribution device includes a spool valve having first and second fluid distribution ports and first and second pilot fluid ports, the spool valve having two surfaces slidable between the first and second pilot ports. a first fluid pipe having a piston and connecting the first thrust bearing and the first pilot port; and the second thrust bearing and the second fluid pipe.
A second fluid pipe is provided that connects to the pilot port;
The thrust bearing lubrication system of claim 1, wherein fluid pressure in the first and second thrust bearings is transmitted to a fluid distribution system. 6. The spool valve further comprises first and second plugs oppositely connected to the two-sided piston, each plug being capable of sliding with the piston to open and close the first and second fluid distribution ports, respectively. The thrust bearing lubricating device according to item 5. 7. A rotating shaft having a thrust collar that can rotate together, a first thrust bearing on one side of the thrust collar, a second thrust bearing on the other side of the thrust collar, and a lubricating fluid supply device for the thrust bearing. In a thrust bearing lubricating system, the lubricating fluid distribution system includes a two-sided piston and a spool valve having first and second valve plugs extending in opposite directions from the two-sided piston to control first and second fluid distribution ports. , opposite sides of the two-sided piston and also first and second pilot fluid ports that connect with the first and second thrust bearings respectively, the spool valves being connected to one or the other side when the bearing pressure of either bearing increases. A device that moves to one side and opens or closes one or the other fluid distribution port to distribute the flow of lubricating fluid to one or the other of the bearings. 8. The thrust bearing lubrication system of claim 7, wherein the thrust bearings are of the same size and the total flow rate of lubricating fluid is the maximum expected flow rate of lubricating fluid required by one of the bearings. 9. The thrust bearing lubrication system of claim 7, wherein one thrust bearing is larger than the other thrust bearing, and the total flow rate of lubricating fluid is the maximum expected flow rate of lubricating fluid required for the larger bearing.