JPH07291187A - Cooling structure for rotary shaft seal - Google Patents

Abstract

PURPOSE:To provide the cooling structure for a rotary seal which can effectively cool a shaft seal without generating heat excess on a slidable even if the peripheral speed of the rotary shaft is increased, and is suitable for the small-sized and high speed performance of the rotary machine and possesses high performance. CONSTITUTION:As for the shaft seal structure for a rotary shaft which is formed by surrounding the outer periphery of sleeve 2 which is coaxially fitted on the outer periphery of the rotary shaft, by an annular sealing member, one or a plurality of radial oil holes E for introducing the lubricating oil in the center hole D drilled in the radial direction in an equal interval at the part where the sleeve 2 is externally fitted in the axial direction hole D on the rotary shaft 1 are provided. Further, a cylindrical recess 2a which is coaxially formed in a recessed from over nearly the whole length in the inner surface part other than both the ends of the sleeve 2 fitted on the rotary shaft 1, and one or a plurality of radial direction holes F which discharge the lubricating oil in the cylindrical recess formed at one and of the cylindrical recess 2a, outside the sleeve 2 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for a rotary shaft seal such as a gland type seal for a rotary shaft of a water jet pump or an air extraction type dry seal.

[0002]

2. Description of the Related Art For example, in a water jet pump used as a propulsion device of a ship, seawater sucked up by a blade wheel 21 from a ship bottom through a suction pipe 22 is impeller wheel 21 as shown in a vertical sectional view of FIG. After being increased in pressure by the guide vanes 23, static pressure is recovered by the guide vanes 23, and then converted into dynamic pressure again at the jet outlet 24 and ejected rearward from the stern. Here, the impeller boss 25 of the impeller 21 and the guide vane boss 26 of the guide vane 23 form an impeller boss chamber A and a guide vane boss chamber B whose outer circumferences face each other, leaving a slight clearance δ. A seal 27 is built in the impeller boss chamber A, and a bearing 28 is built in the guide blade boss chamber B. The oil used for cooling / lubrication enters the guide vane boss chamber B as shown by the black arrow, cools the main shaft, cools / lubricates the bearing, and then is circulated out of the machine. Further, an axial balance hole C is bored in the axial direction of the impeller boss 25 on the inlet side so that seawater that has flowed in through the clearance δ at the mating portion of both bosses can escape from the balance hole C to the impeller inlet side. It has become.

[0003]

By the way, in the gland packing type seal 27 and the air extraction type dry seal of this type, the peripheral speed limit is kept low due to the heat generation of the sliding surface. In particular, if the amount of lubricating oil from the sealing surface is reduced too much, the cooling effect of the leak liquid (lubricating oil) itself on the sliding surface will be insufficient, causing a serious accident such as seizure of the packing. Therefore, for this reason, it is the actual situation that a certain amount of lubricating oil leak must be allowed on the sealing surface.

The present invention has been proposed in view of such circumstances, and it is possible to effectively cool the shaft seal without excessive heat generation on the sliding surface even if the peripheral speed of the rotating shaft is increased. It is an object of the present invention to provide a high-performance rotating shaft seal cooling structure suitable for downsizing and speeding up of rotating machines.

[0005]

To this end, the present invention provides a shaft seal structure for a rotary shaft, in which an outer circumference of a sleeve coaxially fitted to the outer circumference of the rotary shaft is surrounded by an annular seal member. And a plurality of radial oil holes that are formed in the axial center hole of the sleeve at equal intervals in the radial direction to guide the lubricating oil in the central hole to the outer periphery, and the rotary shaft. And a cylindrical recess formed coaxially over the inner surface of the sleeve other than both ends of the sleeve, and lubricating oil in the cylindrical recess formed at one end of the cylindrical recess is discharged to the outside of the sleeve. It is characterized by comprising one or more radial oil holes.

[0006]

With this structure, even when the amount of lubricating oil leak is reduced by increasing the tightening force of the packing, or in the case of a seal such as a dry seal in which cooling by the leak liquid on the sliding surface cannot be expected. , The annular recess formed on the inner surface of the shaft sleeve is communicated with the axial center hole of the spindle shaft end, and the coolant such as the bearing is made to flow into the annular recess, so that the heat generated on the seal sliding surface is Absorb through sleeve. In addition, the cooling / lubricating liquid (oil) is automatically supplied to the annular recess formed on the inner surface of the sleeve by the centrifugal force from the center hole at the end of the spindle through the radial oil hole in the sleeve by the rotational force of the water jet pump. To be done. Then, the cooled liquid (oil) is further circulated back to an oil tank (not shown) through a radial oil hole at one end of the sleeve. As a result, the cooling effect is remarkably improved as compared with the conventional structure. By the way, due to this cooling effect, the peripheral speed limit is allowed to be doubled from the conventional one.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a water jet pump type propulsion device of a ship will be described with reference to the drawings.
FIG. 1 is a vertical sectional view showing a shaft seal portion of the pump.

In the above figure, the outer peripheral surface of the sleeve 2 coaxially fitted on the rotary shaft 1 slides on the seal packing 3. An annular recess 2a is formed on the inner peripheral surface of the sleeve 2 over substantially the entire length except for both ends, and an oil hole F is radially formed at one end of the annular recess 2a. An axial center hole D is bored in the rear end of the rotary shaft 1 to cool the end of the rotary shaft 1. The axial center hole D communicates with the annular recess 2a of the sleeve 2 through the radial oil hole E.

In such a structure, the bearing, etc. are cooled and
As shown by the black arrow, the oil to be lubricated enters the annular recess 2a from the axial center hole D through the radial oil hole E, and then circulates cyclically to the oil tank (not shown) through the radial oil hole F of the sleeve 2. Will be returned.

[0010]

According to the cooling structure for a shaft seal according to the present invention as described above, it is possible to apply a gland packing type seal, an air extraction type dry seal or the like to a region exceeding the conventional peripheral speed limit. . As a result, serious accidents such as seizure can be avoided, and it becomes possible to design a high rotational speed that was forced to be designed at a low rotational speed due to the limit of the peripheral speed, thus making the water jet pump smaller. it can.

In short, according to the present invention, in the shaft seal structure of the rotary shaft, which is formed by surrounding the outer circumference of the sleeve coaxially fitted on the outer circumference of the rotary shaft with the annular seal member, the axial center hole of the rotary shaft. And a single or plural radial oil holes that are bored at equal intervals in the radial direction in the sleeve where the sleeve is fitted and guide the lubricating oil in the central hole to the outer circumference, and are fitted to the rotary shaft. A cylindrical recess formed coaxially over the inner surface other than both ends of the sleeve, and one or more radii formed at one end of the cylindrical recess for discharging lubricating oil in the cylindrical recess to the outside of the sleeve. The directional oil holes make it possible to effectively cool the shaft seal without excessive heat generation on the sliding surface even if the peripheral speed of the rotating shaft is increased, making it suitable for downsizing of rotating machines. High-performance rotary shaft seal cooling structure From getting, the present invention is the extremely valuable industrial.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a shaft seal portion of an embodiment in which the present invention is applied to a hydrojet propulsion device of a ship.

FIG. 2 is an overall vertical sectional view showing a conventional hydrojet pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft (spindle) 2 sleeve 2a inner surface annular recess 3 seal packing 21 impeller 22 suction pipe 23 guide vane 24 jet outlet 25 impeller boss 26 guide vane boss 27 seal 28 bearing A impeller boss chamber B guide vane boss chamber C Balance hole D Axial center hole E Radial oil hole F Radial oil hole

Claims (1)

[Claims] 1. A shaft seal structure for a rotating shaft, wherein the outer periphery of a sleeve coaxially fitted to the outer periphery of the rotating shaft is surrounded by an annular seal member, and the sleeve is the axial center hole of the rotating shaft. A radial oil hole or holes that are provided at equal intervals in the radial direction in the outer circumference of the sleeve to guide the lubricating oil in the center hole to the outer periphery, and other than the both ends of the sleeve fitted to the rotary shaft. A cylindrical recess formed coaxially over the inner surface portion, and one or more radial oil holes formed at one end of the cylindrical recess for discharging lubricating oil in the cylindrical recess to the outside of the sleeve. A cooling structure for the rotary shaft seal, which is equipped with