JPH0742980B2 - Hydrodynamic thrust fluid bearing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydrodynamic thrust fluid bearing having a bearing surface made of an elastic foil, and more particularly to a taper land type bearing tapered by a pad.

[Prior Art] It is known, for example, from JP-A-61-165011 to construct a tapered land type bearing by tapering with a foil pad.

However, in this known bearing, since the pad is connected to the pad foil body at one point, it is necessary to weld the connecting side end of the pad to the back foil laminated under the pad foil to reinforce the pad. . Therefore, there is a drawback that the work is troublesome and the positioning accuracy at the time of welding becomes strict.

Further, since the back foil laminated under the pad foil has a continuous ring shape and has no slits or holes, heat generated in the pad by friction cannot be effectively released to the lower side.

For this reason, there is a drawback that the pad is thermally deformed by heat generation when rotating at a high speed, and the bearing performance is deteriorated.

[Problems to be Solved by the Invention] As described above, according to the conventional thrust bearing, the pad is welded, so that the work is troublesome and the frictional heat generated in the pad cannot be effectively released. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dynamic pressure thrust fluid bearing which solves the above problems of the prior art, does not require welding, and can effectively prevent thermal deformation.

[Means for Solving the Problems] A hydrodynamic thrust fluid bearing of the present invention is configured by laminating a spring foil having a spring function, a bearing foil having a bearing function, and a shim foil having a backup function in order from the top. It

The spring foil has linear protrusions alternately arranged on the front and back along the direction of rotation of the runner of the rotary shaft, and pad insertion windows that interrupt the linear protrusions are provided at appropriate intervals.

The bearing foil integrally has a strippable pad piece, which is a tapered land which can be inserted through the window of the spring foil and supported by the linear projections of the spring foil.

The shim foil has a pillow-shaped projection that supports the linear projection of the spring foil to reinforce the taper land, and is provided with a fluid supply hole that communicates with the window through the cut-and-raised gap between the pad pieces.

[Operation] When the pad piece is inserted through the window of the spring foil, the pad piece rides on the spring foil in a slanted shape, so that a wedge-shaped gap is formed between the pad piece and the runner structurally.

As the runner rotates, the fluid is dragged by its viscosity and forced into the wedge-shaped gap, creating pressure. The sloping pad pieces tend to be pressed downwards by this pressure and try to lie flat, but are supported by the linear projections of the spring foil and the pillows of the shim foil, thus maintaining the taper land.

Further, each pad piece is independently divided by the fluid supply hole communicating with the window through the cut and raised gap between the pad pieces, and exerts the function of the independent bearing, so that the runner tilts under an unbalanced load. However, the taper land has the restoring force and the angular rigidity is large.

On the other hand, the faster the runner rotates, the greater the heat generated by the fluid friction. In proportion to this, the fluid flowing from the fluid supply hole also increases, and this fluid effectively cools the pad pieces.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 2 shows an exploded view of an example of the dynamic pressure thrust fluid bearing of the present invention. As can be seen from the figure, this bearing consists of three disc-shaped foils punched out around the rotary shaft hole, and a spring foil 10, a bearing foil 20, and a shim foil 30 are laminated in order from the upper layer to the lower layer.

The spring foil 10 has a large number of linear projections 1 arranged in a staggered manner on the front and back sides thereof and extending in the radial direction along the rotational direction (arrow ω) of a runner (not shown) of the rotary shaft. is doing. The linear protrusion 1 is formed by digging the land portion by hot etching. The etching location is shown in satin. Further, in the spring foil 10, a plurality of windows 2 for inserting the pad pieces are similarly punched by photoetching at appropriate intervals so as to interrupt the linear projections 1.
In the illustrated example, six windows 2 are provided, and four linear projections 1 are provided between the windows 2, but the number of these is not limited to that in the illustrated example. The pitch between the linear protrusions 1 is gradually narrowed in the rotation direction between the windows 2 to increase the rigidity.

The bearing foil 20 corresponds to the window 2 and has six pad pieces 11
have. The pad piece 11 is fan-shaped and is formed by etching a substantially inverted U-shaped slit groove around the pad piece 11 by etching so that approximately 2/3 of its length can be cut and raised. The slit groove 12 as a cut and raised gap between the tailing edge of the pad piece 11 and the leading edge of the adjacent pad piece 11 is slightly wider than the other slit grooves for use as a fluid introduction hole. When the foils are stacked, in order to make the pillow-like projections 21 of the shim foil 30 effective, the land portion of the foil except the pad pieces 11 is dug down by etching.

The shim foil 30 has on its surface six pillow-like projections 21 for supporting the pad pieces 11 of the bearing foil 20 via the linear projections 1 of the spring foil 10. The pillow-like protrusions 21 are provided to counter a load that cannot support the pad piece 11 by the spring foil 10. The position of the pillow-like protrusion 21 with respect to the pad piece 11 is placed at a position where the fluid film pressure shows a maximum value. As described above, the land portion is dug down by photoetching to form the pillow-shaped protrusion 21. Further, the shim foil 30 is provided with a fluid supply hole 22 for positively supplying a fluid from the outside of the bearing to the inside of the bearing. The fluid supply hole 22 is a long hole that extends in the radial direction, and the outer end in the radial direction extends to the mounting hole 24 of the mounting piece 23 that projects outside the outer circle of the disk-shaped shim foil 30. Further, the position of the fluid supply hole 22 is set on the side opposite to the rotation direction side of the window 2 of the spring foil 10 and the pad piece 11.
The fluid supplied from the fluid supply hole 22 can be introduced into the window 2 through the slit groove 12 so as to communicate with the slit groove 12 therebetween.

Mounting holes 4, 14, 24 are provided on the outer circumference of each foil 10, 20, 30 described above.
Mounting pieces 3, 13, and 23 that are opened are respectively projected. In the embodiment, six pieces are provided, but if these foils 10, 20, 30 are made to coincide with each other, the positioning between the foils is performed.

The mounting piece for the mounting hole may not be a protruding piece as shown in the illustrated example, but may be a circular outer edge portion formed by enlarging the foil outer circle a little more radially outward.

FIG. 3 is an assembly drawing, in which the pad piece 11 of the bearing foil 20 of the second layer is inserted through the window 2 of the spring foil 10 of the first layer so that it can ride on the uppermost layer. Inserting is performed up to about 2/3 of the total length of the pad piece 11 that can be cut and raised. When inserted so far, as shown in FIG. 1, the insertion pad piece 11 rides on the edge of the window 2 and structurally forms an inclined plane or taper land above the spring foil 10 from the beginning.

As shown in FIG. 4, the laminated foil is used in the bearing case 40.
Although it is supported above, if a groove 41 for fluid guide is provided on the surface of the bearing case 40 corresponding to the position of the fluid supply hole 22, the pad piece 11
The fluid is more smoothly supplied to.

When the runner 50 receiving the load W moves in the direction of the arrow,
The pad piece 11 is supported by the spring foil 20 and the shim foil 30 to form a tapered land A as shown in the drawing, and has a peak at the position of the pillow-like protrusion 21 and has a fluid supply hole 22 or a groove 41.
A wedge-shaped fluid film pressure is created that exhibits atmospheric pressure at the location.

At this time, the external fluid introduced from the groove 41 and supplied from the fluid supply hole 22 has a cooling function of positively cooling the pad piece 11.

[Effects of the Invention] The present invention has the following effects.

(1) Since the wedge-shaped gap is formed only by inserting the pad piece of the bearing foil from the window of the spring foil, the work is much easier than the conventional one which requires welding. Further, since the pad piece inserted through the window is supported by the linear projection of the spring foil and the pillow projection of the shim foil, the taper land can be secured even when the rotation speed increases, and excellent high-speed stability is exhibited.

(2) Since each pad piece is independently divided by the fluid supply hole that communicates with the window through the cut and raised gap between the pad pieces,
Even if an unbalanced load is applied to the runner, the restoring force is easily exerted and the angular rigidity is extremely large. Further, since the fluid is positively supplied from the fluid supply hole, the cooling action works and it is extremely strong against thermal deformation.

[Brief description of drawings]

FIG. 1 is an exploded cross-sectional view of an essential part in a circumferential direction showing an embodiment of a dynamic pressure thrust fluid bearing according to the present invention, FIG. 2 is an overall exploded plan view of the thrust fluid bearing shown in FIG. 1, and FIG. 3 is the same. FIG. 4 is an assembly plan view and FIG. 4 is a thrust foil state diagram and a fluid film pressure characteristic diagram at a high speed. In the figure, 1 is a linear protrusion, 2 is a window, 10 is a spring foil, 11 is a pad piece, 12 is a slit groove as a gap that is cut and raised, 20 is a bearing foil, 21 is a pillow-like protrusion, and 22 is a fluid supply hole. , 30 is a shim foil, 50 is a runner, and A is a taper land.

Claims (1)

[Claims] 1. A spring foil having linear projections arranged alternately on the front and back sides along the rotation direction of a runner of a rotary shaft, wherein the spring foils are provided with windows for interrupting the linear projections at appropriate intervals. The bottom of the spring foil with a taper land which can be inserted through the window of the spring foil and supported on the linear projections of the spring foil. A shim foil with pillow-shaped projections that support the linear projections of the spring foil to reinforce the taper land is provided in the lower layer of the bearing foil, and the shim foil communicates with the window through the cut and raised gap between the pad pieces. A dynamic thrust fluid bearing having a fluid supply hole provided therein.