JP2002106721A - Labylinth seal structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a seal effect of a labylinth seal structure provided on an axial flow type or a mixed flow type fan. SOLUTION: A labylinth seal structure 23 is formed between an outer peripheral surface 30a on a rotating side 30 and an inner peripheral surface 31a on a fixed side 31 opposed to the outer peripheral surface 30a. Annular throttle pieces S1 to S3 are projected on the outer peripheral surface 30a. An annular recessed groove 24 is provided on the inner peripheral surface 31a. Back flow G is divided into expansion chambers B1 and B2 and the recessed groove 24 to generate eddy current and the flow rate resistance is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a labyrinth seal structure formed between an outer peripheral surface on a rotating side and an inner peripheral surface on a fixed side opposed thereto, and more particularly, to provide an annular concave groove on the inner peripheral surface on the fixed side. The present invention relates to a labyrinth seal structure having an improved sealing effect.

[0002]

2. Description of the Related Art In a rotating device such as a fan or a pump, a gap between a rotating side such as a shaft and a fixed side such as a casing is often sealed with a labyrinth seal. For example, an axial or mixed flow fan used for cooling a radiator of an automobile has a boss portion fixed to a drive shaft that is rotated by a drive source such as an engine or a motor, and a plurality of blades are radially provided on the boss portion. The wings are connected to each other by a ring, and a cylindrical portion of the shroud is provided radially outside the ring. A labyrinth seal structure for preventing backflow is formed between the ring on the rotating side and the cylindrical portion of the shroud on the fixed side.

FIG. 6 is a side longitudinal sectional view of a conventional mixed flow fan for cooling a radiator or the like of an automobile. A fan 1 is a drive shaft 2 rotated by a crankshaft of an engine (not shown).
And a boss 3 fixed to the drive shaft 2 and a plurality of wings 4 radially arranged from the boss 3. The rotation of the wing 4 generates a wind from the left side to the right side in the drawing. The tips of the wings 4 are connected to each other by a ring 5, and a cylindrical portion 7 of a shroud 6 is arranged with a predetermined gap so as to surround a radially outer side of the ring 5. Further, a plurality of throttle pieces S each formed of an annular ridge are provided radially outward at predetermined intervals along the outer periphery of the ring 5. In this example, a ring-shaped bell mouth M for suppressing turbulence of air flow and generation of a vortex is provided at both ends of the ring 5 in the axial direction.
Are also used as the aperture pieces S at both ends.

On the other hand, the cylindrical portion 7 is bolted to the funnel-shaped connecting member 8 at its flange portion to form the shroud 6. The connecting body 8 is fixed to the periphery of the core of the radiator 9. The inner peripheral surface of the cylindrical portion 7 faces the outer peripheral surface of the ring 5 with a predetermined gap, and a so-called direct labyrinth is formed by a plurality of throttle pieces S provided on the inner peripheral surface and the outer peripheral surface of the ring 5. A seal structure 10 is formed. In such a straight-through labyrinth seal structure 10, a throttle port is formed by the gap between the inner peripheral surface of the cylindrical portion 7 and the tip end of the throttle piece S, and a backflow from the downstream side of the blade 4 causes the throttle port to form the throttle port. A backflow that isentropically expanded when passing through and the decelerated backflow is restored to a static temperature with an equal pressure in a space (expansion chamber) in the middle of the adjacent throttle piece S, thereby exerting a sealing effect. It is.

FIG. 7 is a partially enlarged cross-sectional view of the direct labyrinth seal structure 10 in FIG. 6, and the same parts as those in FIG. 6 are denoted by the same reference numerals. For simplicity, only three (S1 to S3) aperture pieces S on the outer peripheral surface of the ring 5 are illustrated. The backflow G from the right side of the drawing flows through the gap between the cylindrical portion 7 and the throttle piece S in a blow-by shape in a direction opposite to the direction of blast of the fan.
The flow is divided in B2 to form a vortex, and the flow resistance of the backflow G is increased.

FIG. 8 is a partially enlarged cross-sectional view in which a staggered labyrinth seal structure is employed instead of the direct through type of FIG. The staggered labyrinth seal structure 11 has a plurality of throttle pieces S (S <b> 1 to S <b> 3) provided on the outer periphery of the ring portion 5 and a plurality of reverse throttle pieces projecting radially from the inner peripheral surface of the cylindrical portion 7 of the shroud 6. R (R1, R2) is provided. Then, the backflow G is diverted by the reverse throttle R, and a part of the backflow is diverted in the expansion chambers B1 and B2 formed between the throttles S to form a vortex to reduce the reverse flow. Therefore, the staggered labyrinth seal structure 11 generally has a greater effect of suppressing the backflow (seal effect) than the direct-flow labyrinth seal structure 10.

[0007]

However, in the conventional labyrinth seal structure, the design is focused on how the expansion chamber on the rotating side formed by the throttle piece S effectively acts to suppress the backflow. Is done. However, in such a structure, even if the shape and position of the expansion chamber (or the reverse restricting piece R) are optimized, the labyrinth is increased in multiple stages (the restricting piece S and the reverse restricting piece R) in order to further enhance the backflow suppressing effect. There is no other way than to increase the number of However, practically, there is a limit due to dimensional restrictions in the width direction, costs, or manufacturing problems. Therefore, an object of the present invention is to solve such a problem in the conventional labyrinth seal structure and to provide a new labyrinth seal structure for that purpose.

[0008]

That is, the present invention provides a labyrinth seal structure 23 formed between an outer peripheral surface 30a of a rotating side 30 and an inner peripheral surface 31a of a fixed side 31 opposed thereto.
It is. The outer peripheral surface 30a of the rotating side 30 is provided with an annular throttle piece S protruding in the radial direction, and the inner peripheral surface 31a of the fixed side 31 is provided with an annular concave groove 24. (Claim 1). In the above-mentioned labyrinth seal structure, an annular reverse drawing piece R protruding in the radial direction can be provided on the inner peripheral surface on the fixed side avoiding the concave groove 24 (claim 2). In the above labyrinth seal structure,
The rotating side 30 may be the ring 5 connecting the blades 4 of the fan 1, and the fixed side 31 may be the cylindrical portion 7 of the shroud 6 for guiding air.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a front view of a mixed flow fan equipped with a labyrinth seal structure of the present invention for mounting on a vehicle, FIG. 2 is a rear view thereof, and FIG. 3 is a sectional view taken along line AA of FIG. The same parts as those in FIG. 6 are denoted by the same reference numerals. In these figures, a boss 3 is fixed to a drive shaft 2 of a motor 20 arranged at the center of the fan 1, and a plurality of blades 4 are radially protruded on the upstream side of the boss 3 in the axial direction. . The tips of the wings 4 are integrally connected to each other by a ring 5, and a cylindrical portion 7 of a shroud 6 is arranged radially outside the ring 5 with a gap therebetween. Further, at the rear end of the shroud 6, a plurality of stays 21 are connected between the inner peripheral surface of the cylindrical portion 7 and the center of the fan 1, and the motor mounting portion 32
Is provided, and the motor 20 is fixed there.

The ring 5 constitutes the rotating side 30 in the present invention, and the tubular portion 7 constitutes the fixed side 31 in the present invention.
A labyrinth seal structure 23 is formed between the rotating side 30 and the fixed side 31. And the inner peripheral surface 31 of the fixed side 31
a is provided with an annular concave groove 24. In addition, shroud 6
The fan 1 and the fan 1 can be made by molding with resin. Further, a power cable 22 is extended from the motor 20.

FIG. 4 shows a labyrinth seal structure 23 of the present invention.
It is the elements on larger scale sectional view. In this example, the outer circumferential surface 30a of the rotating side 30 constituted by the ring 5 is radially 3
The three stop pieces S (S1 to S3) are protruded, and three concave grooves 24 are provided on the inner peripheral surface 31a of the fixed side 31 constituted by the cylindrical portion 7. The groove 24 on the upstream side in the reverse flow direction is located at an intermediate portion between the throttle pieces S1 and S2, the groove 24 at the middle faces the throttle piece S2, and the groove 24 on the downstream side is located between the throttle pieces S2 and S3. To position. Each groove 24
Open in the inner peripheral surface 31a, and their axial width a is smaller than the axial length b of the inner peripheral surface 31a in contact therewith. As in the case of FIG. 7, a part of the backflow G is divided into the two expansion chambers B1 and B2 on the fixed side 30 to generate eddies, and another part is divided into the three concave grooves 24. The vortex flows to generate vortices, and the action of the vortices greatly increases the flow resistance of the backflow G.

FIG. 5 is an enlarged sectional view of a staggered labyrinth structure according to another embodiment of the present invention. On the inner peripheral surface 31a of the fixed side 31 formed by the cylindrical portion 7, two reverse stop pieces R (R1, R2) protruding in the radial direction are provided. The tip of the reverse throttle R1 located on the upstream side in the reverse flow direction extends above the expansion chamber B1 formed at the intermediate portion between the throttles S1 and S2 on the rotating side 30, and the reverse throttle R located on the downstream side.
The tip of 2 extends above the expansion chamber B2 formed at the intermediate portion between the throttle pieces S2 and S3 on the rotation side 30. Note that the inner diameter of the tip of each reverse drawing piece R is slightly larger than the outer diameter of the tip of each drawing piece S, so that the ring 5 can be easily inserted into the cylindrical portion 7 from the axial direction. . And reverse drawing piece R1
And one annular concave groove 24 is provided in contact with the upstream side of the other, and another annular concave groove 24 is provided between the reverse drawing pieces R1 and R2. As shown in the drawing, the backflow G is made up of each throttle piece S and each reverse throttle piece R.
And a part of the flow is divided into the expansion chambers B1 and B2 formed on the rotating side 30 and the concave grooves 24 provided on the fixed side 31 to further increase the flow resistance of the backflow G. Let it.

In the staggered labyrinth seal structure 23 shown in FIG.
When it is configured to extend into the expansion chambers B1 and B2 formed at 0, the detour of the backflow is increased and the effect of suppressing the backflow is enhanced. However, such a configuration causes another problem that it is difficult to assemble the rotary side 30 by inserting it into the fixed side 31 from the axial direction. Therefore, in this case, this problem can be avoided by making these reverse stop pieces R deformable in the axial direction. In FIG. 3, the reverse drawing piece R3 is elastically deformed, and may be made of an elastic material such as plastic or rubber and the thickness of the reverse drawing piece R may be made extremely thin. With this configuration, when the rotating side 30 is inserted into the fixed side 31 from the axial direction, each reverse stop piece R comes into contact with the stop piece S and falls down in the axial direction, and returns to the original state after passing.

The labyrinth seal structure 23 in FIG. 4 has three aperture pieces S and three concave grooves 24, and the labyrinth seal structure 23 in FIG. 5 has three aperture pieces S, two reverse aperture pieces R, and a further concave. Although the number of the grooves 24 is two, the numbers of the diaphragm pieces S, the concave grooves 24, and the reverse diaphragm pieces R are not limited thereto, and can be arbitrarily increased or decreased. Further, the labyrinth seal structure of the present invention can be applied to a seal of a pump or other rotating equipment other than the fan 1 mounted on an automobile.

[0015]

As described above, in the labyrinth seal structure of the present invention, the annular throttle piece S protruding in the radial direction is provided on the outer peripheral surface on the rotating side, and the annular groove is provided on the inner peripheral surface on the fixed side. As a result, the backflow shunts into the expansion chamber formed on the rotation side to form a vortex, and at the same time, the backflow shunts into the concave groove to form a vortex, so that the flow resistance is significantly increased. Therefore, the effect of suppressing the backflow can be significantly increased without increasing the axial dimension. In the above labyrinth seal structure, an annular reverse throttle piece R protruding in the radial direction from the inner peripheral surface on the fixed side, avoiding the concave groove portion, can be provided, whereby the effect of suppressing the backflow can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a front view of a mixed flow fan to which a labyrinth seal structure of the present invention is applied.

FIG. 2 is a rear view of FIG. 1;

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a partially enlarged sectional view showing one example of a labyrinth seal structure of the present invention.

FIG. 5 is a partially enlarged sectional view showing another example of the labyrinth seal structure of the present invention.

FIG. 6 is a side view of a conventional mixed flow fan mounted on a vehicle.

7 is a partially enlarged cross-sectional view of the labyrinth seal structure in FIG.

FIG. 8 is a partially enlarged cross-sectional view of a staggered labyrinth seal structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fan 2 Drive shaft 3 Boss part 4 Wing 5 Ring 6 Shroud 7 Cylindrical part 8 Connecting body 9 Radiator 10 Direct type labyrinth seal structure 11 Staggered type labyrinth seal structure 20 Motor 21 Stay 22 Power cable 23 Labyrinth seal structure 24 Concave Groove 30 Rotation side 30a Outer peripheral surface 31 Fixed side 31a Inner peripheral surface 32 Motor mounting part B Expansion chamber S Restrictor R Reverse restrictor M Bellmouth

Claims (3)

[Claims] 1. In a labyrinth seal structure 23 formed between an outer peripheral surface 30a of a rotating side 30 and an inner peripheral surface 31a of a fixed side 31 opposed thereto, the outer peripheral surface 30a of the rotating side 30 projects radially. A labyrinth seal structure wherein an annular throttle piece S is provided and an annular concave groove 24 is provided on an inner peripheral surface 31a of the fixed side 31. 2. A labyrinth seal structure in which an annular reverse throttle piece R protruding in the radial direction is provided on the inner peripheral surface 31a of the fixed side 31 avoiding the concave groove 24. 3. The ring 5 according to claim 1, wherein the rotating side 30 is connected to each of the blades 4 of the fan 1.
The labyrinth seal structure in which the fixed side 31 is the cylindrical portion 7 of the shroud 6 for guiding air.