JPH0721925Y2 - Dual bearing for seals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to improvements in bearings and gas seals used in gas compressors, gas expanders and the like.

[Conventional technology]

Examples of conventional bearings and gas seals are shown in FIGS. 2 and 3.

FIG. 2 is an example of use of a conventional oil film seal and bearing. In this case, since the functions of the seal 01 and the bearing 02 are separated, the respective operations are reliable. Note that
Reference numeral 03 is a shaft and 04 is a housing. FIG. 3 shows an example in which both the seal and the bearing are used. In this case, oil is pumped to the central circumferential groove to provide a sealing function. Note that
05 indicates a seal and 06 indicates an axis.

[Problems to be solved by the device]

By the way, in the case of the above-mentioned example of the prior art in which the oil film seal and the bearing are separately arranged, the respective operations are reliable, but the entire length of the shaft, particularly the overhang portion becomes long, and vibration stabilization Affect sexuality. For this reason, the bearing portion is required to have excessive performance, which is disadvantageous in terms of friction loss.

Also, in the conventional system that integrates the oil film seal and the bearing, there is a large pressure drop between the circumferential groove and the bearing clearance on the anti-load side, especially when the eccentricity is high, and the cavity penetrates near the circumferential groove. However, there is less margin for sealing when the load changes. For this reason, the total width has to be relatively large,
There is a problem that high refueling pressure is required.

The present invention is intended to provide a new seal-bearing journal bearing which solves the above-mentioned problems.

[Means for Solving the Problems]

Therefore, in the seal bearing journal bearing of the present invention, the oil film seat portion and the dynamic pressure journal bearing portion are arranged in parallel on both sides with a single circumferential groove for supplying sealing oil provided at the bearing end as a boundary. In the journal bearing that also serves as a seal and is integrated, a plurality of semicircular grooves are provided in the upper half portion of the bearing portion.

[Action]

The seal bearing journal bearing of the present invention as described above has the oil film seal portion and the bearing portion integrated with each other to allow the bearing to share the sealing function and to provide the bearing with an anti-circumferential groove to provide a labyrinth-like function. The pressure drop between the circumferential groove of the seal and the bearing clearance is suppressed, giving a margin to the sealing performance when the load changes. Further, this has the effect of suppressing the entire width of the bearing, suppressing the bearing loss, and reducing the oil supply pressure.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1 of the drawings. FIG. 1 (a) is a side sectional view of a seal and bearing of the present invention, and FIG. 1 (b) is a front sectional view of a two-arc bearing. FIG. 1 (c) is a front sectional view in the case of an offset bearing.

In these figures, the seal bearing 1 is shown in FIG. 1 (a).
As shown in the side sectional view, the left side is composed of the seal part and the right side is the bearing part with the circumferential groove 1a guiding the seal oil as the boundary, and the semi-circular groove 1b is provided on the anti-load surface of the bearing part. There is. As the type of the seal / bearing 1 according to the present invention, a two-arc bearing 1c type as shown in FIG. 1 (b) and an offset bearing 1d type as shown in FIG. 1 (c) are conceivable. Of course, a perfect circle may be used depending on the performance. However, the anti-load surface of the two-circle bearing 1c or the offset bearing 1d is also required to have a bearing action, and therefore the method of cutting the groove is shifted as shown in this embodiment (general semicircular groove is seen in the axial direction. In the cross section of the bearing, it is said that the symmetrical arrangement with respect to the vertical axis is designed by changing the phase hand or offsetting it.) It is necessary to provide a circumferential groove. Reference numeral 2 is a rotor.

Next, the operation and effect of the present invention will be described with reference to FIGS. FIG. 4 is an explanatory view of the pressure distribution in the bearing in the case of the above-mentioned conventional device, and FIG. 5 is an explanatory view of the pressure distribution in the bearing in the case of the bearing of the present invention. First, the shaft is stopped and a semicircular groove is provided. The pressure distribution in the bearing in the case of the invention and in the conventional case without the semicircular groove shown in FIGS. 2 and 3 will be described. As is apparent from FIG. 5, in the present invention, a plurality of semicircular grooves are provided in the upper half of the bearing portion, so that the pressure distribution has a stepwise shape, and the pressure distribution is partially shown in FIG. There is a portion where the pressure is higher than the pressure distribution, and the pressure retention in the bearing portion is improved. This is the labyrinth effect.

It is known that under incompressible fluid / laminar flow conditions the labyrinth effect results in a decrease in the axial flow drag coefficient, ie, an increase in the flow rate. Therefore, the pressure gradient around the narrow clearance is inevitably large, and the pressure level near the right end of the bearing is higher than in the straight case.

Next, the situation when the shaft rotates will be described with reference to FIGS. 6 and 7. FIG. 6 shows the case of the conventional device, and FIG. 7 shows the case of the bearing of the present invention.

The upper half of the bearing is generally in the form of a widening wedge in which the clearance is expanded in the rotational direction of the shaft. In such a case, a negative pressure is generated in the normal bearing, and a cavity is generated due to the deposition of air bubbles in the oil and the entrainment of air from the end, and the pressure becomes atmospheric pressure. This effect is shown in FIGS. 6 and 7 in accordance with FIGS. 4 and 5. What is important is that the groove pressure P1'P2 'does not drop significantly compared to the static pressure P1P2 due to the dynamic pressure effect during rotation. This is because the negative pressure generation area is limited to the half circumference where the bearing clearance expands and becomes a wedge. Therefore, the positive pressure part always touches the groove. This is because it occurs and the groove pressure is guaranteed. That is, the suppression of the pressure drop described above in the specification is the effect of FIGS. 6 and 7.

Next, regarding the margin of sealing performance against load fluctuation,
This will be described with reference to FIGS. When the load applied to the shaft fluctuates and the shaft is pushed down, a large negative pressure is momentarily generated due to the squeeze effect due to the small clearance. The pressure distribution due to the negative pressure effect at the time of steady rotation balances with the surrounding pressure condition and takes the form shown in FIGS. 6 and 7 above, so that the pressure Ps of the entire circumferential groove can be kept constant. . However, the momentary generation of a large negative pressure causes a temporary shortage of oil supply to the oil film seal part and the bearing part,
This causes an instantaneous drop in the groove pressure on the entire circumference, and in the case of the conventional device, a gas channel as shown in FIG. 8 is created to cause gas leakage from the left end to the right end. On the other hand, in the case of the bearing of the present invention having a half-circumferential groove, as shown in FIG. 9, since oil is supplied from the groove to the negative pressure portion of the clearance, the cavity generated by the negative pressure communicates with the gas channel. Hard to generate. This is the margin of sealing performance.

The seal bearing journal bearing according to the present invention is configured in this manner so that the bearing also has a seal function, and the semi-circular groove 1b provided on the bearing anti-load surface imparts a labyrinth function to enhance the seal effect.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the technical idea of the present invention.

[Effect of device]

As described above, the seal bearing journal bearing of the present invention provides the following effects.

(1) By combining the oil film part and the dynamic pressure journal bearing part, allowing the bearing to share the sealing function, and further providing a plurality of semicircular grooves in the bearing metal on the anti-load side of the bearing With such a function, it is possible to suppress a large pressure drop between the circumferential groove of the seal portion and the bearing clearance as in the prior art, and to give a margin to the sealing performance when the load changes.

(2) As a result, the overall width of the bearing can be suppressed to be smaller than that of the conventional one, and the bearing loss can be suppressed.
The oil supply pressure can also be reduced.

(3) Compared to the conventional type in which the oil film seal and the bearing are separately placed, the total length of the rotor can be shortened, so that the vibration safety of the rotary shaft system is significantly improved.

[Brief description of drawings]

FIG. 1 is a side sectional view and a front sectional view of a seal-bearing according to the present invention, FIGS. 2 and 3 are side sectional views of a conventional bearing, and FIGS. 4 and 5 are conventional devices when a shaft is stationary. And FIG. 6 and FIG. 7 are explanatory views showing the pressure distribution in the bearing of the present invention bearing, and FIGS. 6 and 7 are explanatory views showing the pressure distribution in the bearing of the conventional device and the bearing of the present invention when the shaft is rotated, FIG. 8 and FIG. FIG. 4 is an explanatory diagram of a margin of sealing performance between the conventional device and the bearing of the present invention.

Claims (1)

[Scope of utility model registration request] 1. An oil film sheet portion and a dynamic pressure journal bearing portion are integrated by arranging them in parallel on both sides with a single circumferential groove as a circumferential groove for supplying sealing oil provided at the bearing end. In the journal bearing for sealing and dual use, a plurality of semicircular grooves are provided in the upper half of the bearing portion.