JPH0814056A - Centrifugal supercharger - Google Patents

Abstract

PURPOSE:To provide a low cost labyrinth seal to prevent a worker from being troubled by management of the gap of the labyrinth seal, improve assembly properties and sealing performance, reduce weight, and improve reliability by a method wherein the labyrinth seal is fixed to the end face of a bearing holder subassembled on a sun gear shaft. CONSTITUTION:A labyrinth seal 8 being an air seal is previously fixed to the end face of a bearing holder 7 subassembled on the sun gear shaft 13 of an impeller 1. The impeller 1 is assembled in a device even when a mounting error of a bearing holder 7 to a casing flange part 6, i.e., the mounting error of the rotary shaft of the impeller 1, is produced because of a backlash occurring to a thrust bearing 4, the bearing holder 7, the labyrinth seal 8, and the impeller 1 is not changed in a relation position in an axial direction. Thus, a labyrinth gap is kept at a constantly proper value between the properly set labyrinth seal 8 and the back of the impeller 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal supercharger installed in the intake system of an internal combustion engine.

[0002]

2. Description of the Related Art Centrifugal turbochargers of this type have excellent responsiveness due to crankshaft drive, which is an advantage of superchargers, low boost and high output performance, and efficiency at high speed, which is an advantage of turbochargers. It is simple and compact, and there is no confinement of pressurized fluid due to the unique method of centrifugal pressurization. If the flow rate is reduced at a constant rotation speed, the driving horsepower will increase even if the pressure ratio increases. Since it is decreasing, it is attracting attention as an extremely efficient supercharger.

An example of such a centrifugal supercharger disclosed in Japanese Patent Laid-Open No. 5-11206 will be briefly described with reference to FIG. 2. It is driven by a supplementary drive belt or the like from a crankshaft of an engine (not shown). The casing 26 of the centrifugal air compressor that constitutes the centrifugal supercharger
An impeller 21 formed by a large number of fans attached to the impeller shaft 33 is rotated at a high speed by an impeller shaft 33 that is rotated at a high speed by being accelerated by a speed increasing mechanism housed in the intake pipe from an air cleaner (not shown). The air in the intake passage 30 in the axial direction sent through is pressurized by the centrifugal force in the radial direction and is discharged from the radial passage to the pressurizing volute 22 in the circumferential direction at high pressure.
The high-pressure air will be subjected to high-power combustion in the internal combustion engine.

In such a centrifugal supercharger, a lower labyrinth seal 29 is arranged so that the lubricating oil between the rotating shaft portion of the impeller 21 and the casing 26 does not leak. On the other hand, the impeller 21 rotates at an ultra-high speed to generate high heat so that the impeller 21 takes in the atmosphere.
Need to cool the back of the. Therefore, a cooling passage is provided from the extraction passage 23 adjusted by the extraction valve 24 to the back air chamber 38 of the impeller 21. An upper labyrinth seal 28 is installed between the end surface of the casing 26 and the back surface of the impeller 21. As a result, it is possible to prevent the leakage of the lubricating oil that has leaked from the lower labyrinth seal 29, and also to appropriately maintain the pressure of the rear air chamber 38 of the impeller 21.

Further, in FIG. 3, as a second conventional example, the actual fairness 4
It shows what was described in Unexamined-Japanese-Patent No. 33364. In this example, a lower labyrinth seal 29 is installed on the inner peripheral portion of a bearing holding member 27 that supports the rotating shaft of the impeller 21, and a ring 32 that is integral with the turbine housing 37 is provided.
When the bearing holding member 27 is fixed by the bolts 34, the labyrinth plate 31 is clamped and fixed, and the inner peripheral portion of the labyrinth plate 31 and the impeller 2 are fixed.
1. An upper labyrinth seal 28 is provided between the inner periphery of the back surface of the No. 1 and a labyrinth plate 39 is provided on the back surface of the labyrinth plate 31 on the bearing holding member 27 side so that the labyrinth plate 31 undergoes thermal deformation during high heat. Is to prevent. Reference numeral 23 indicates a cooling air passage, and 38 indicates a rear air chamber.

[0006]

With respect to such a conventional labyrinth seal, particularly the upper labyrinth seal 28 installed in the rear air chamber 38 on the rear side of the impeller, the gap distance from the rear side of the impeller is very important, and the labyrinth gap is very important. Is small, the negative pressure in the rear air chamber 38 of the impeller becomes large, which is sucked by the air flow directed to the pressure volute in the circumferential direction from the radial passage that is pressurized by the radial centrifugal force due to the rotation of the impeller, and conversely. If the labyrinth gap is large, the negative pressure in the rear air chamber 38 of the impeller will be small. When the negative pressure in the rear air chamber 38 becomes large, the chances of the lubricating oil leaking from the lower labyrinth seal 29 increase, and when the labyrinth gap becomes large and the negative pressure in the rear air chamber 38 becomes small, this also becomes the upper labyrinth seal 28. This will lead to leakage of lubricating oil from the. Therefore, it is extremely important to assemble the device with proper labyrinth clearance.

However, in any of the above-mentioned conventional examples, the upper labyrinth seal 28 has the impeller 2
Since it is installed on the end surface side of the casing 26 that is integral with the turbine housing 37 to which the rotating shaft 1 is assembled,
By assembling the impeller 21, a labyrinth gap in the axial direction is formed. Therefore, in the conventional example of this type, if there is looseness of the thrust bearing or an assembly error of the rotary shaft of the impeller, the labyrinth seal performance is poor, and it takes time and labor to manage the labyrinth clearance when installing the impeller. In short, the assembly performance was inferior. Further, in the structure shown in FIG. 2, since the upper labyrinth seal 28 is installed near the outer peripheral end of the impeller 21, the diameter is large, so that the weight is increased and the area to be sealed is large, so that the labyrinth seal has a large sealing performance. Was also inferior. From such a thing,
The present invention solves the above-mentioned conventional problems and is excellent in assembling without being bothered by the gap management of the labyrinth seal,
Provided is a centrifugal supercharger equipped with a labyrinth seal which has a high sealing performance, a light weight, a high reliability and a low cost.

[0008]

Therefore, in the present invention,
As a means for solving the above-mentioned conventional problems, an impeller rotating by receiving power from a crankshaft of an engine through a speed-increasing device pressurizes air in an axial intake passage with a radial centrifugal force to form a circle. In a centrifugal supercharger consisting of a centrifugal air compressor that discharges from a circumferential pressure volute, a labyrinth seal, which is an air seal installed in the passage that sends cooling air from the ventilation hole to the back air chamber of the impeller, The sun gear shaft, which is a rotating shaft, is fixed to an end surface of a bearing holder that is sub-assembled to the sun gear shaft so as to pivotally support the sun gear shaft, which is a means for solving the problem. Further, according to the present invention, the bearing holder is press-fitted into the casing flange portion.

[0009]

Therefore, according to the present invention, by the above means, the cooling air is supplied from the ventilation hole to the end surface of the bearing holder 7 sub-assembled to the sun gear shaft 13 to pivotally support the sun gear shaft 13 which is the rotation shaft of the impeller 1. Since the labyrinth seal 8 which is an air seal installed in the passage to the rear air chamber of the impeller is fixed in advance,
Even if the mounting error of the bearing holder 7 to the casing flange portion 6, that is, the mounting error of the rotating shaft of the impeller 1 occurs due to the backlash of the thrust bearing 4 caused by mounting the impeller 1 in the apparatus, the bearing holder 7 and the labyrinth seal. Since the axially related positions of the impeller 8 and the impeller 1 do not change, a properly set labyrinth gap between the labyrinth seal 8 and the back surface of the impeller 1 is always maintained properly. Also,
In the present invention, the bearing holder 7 is press-fitted into the casing flange portion 6 by shrink fitting, etc., but is formed between the casing flange portion 6 and the bearing holder 7 which absorb the thrust force generated when the impeller 1 operates. Unlike the conventional one, it is not necessary to interpose a shim or the like for adjusting the labyrinth seal and the back surface of the impeller in consideration of the labyrinth gap, and the stepped portion 10 may be directly contacted to the step 10 for assembly. Since labor is not required, the labyrinth clearance management at the time of assembling the impeller becomes unnecessary. Moreover, the casing flange portion 6
Since the labyrinth seal 8 is installed on the end face of the small-diameter bearing holder 7 which is press-fitted into the inner periphery of the bearing, the diameter can be made smaller than that of the conventional one, and therefore the weight is reduced and the cost is reduced, and the seal should be made. Since the area is small, the sealing performance as a labyrinth seal is improved and the reliability is high.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a main part of one embodiment of the centrifugal supercharger of the present invention. Although not shown, in the vicinity of the left end of the sun gear shaft 13 to which the impeller 1 is attached at the end in the drawing, a plurality of pinion gears that are inscribed and meshed with the internal gear of the speed increasing device formed of a planetary gear are engaged. Sun gear is engraved. As a result, the rotation of the internal gear is increased, the pinion gear is rotated, and the sun gear meshing with these pinion gears is rotated at high speed. The sun gear shaft 13 is axially supported on the inner circumference of the bearing holder 7 with a spacer 16 interposed by a floating bush 5 that can withstand ultra-high speed rotation. A lubricating oil passage 11 is connected to the floating bush 5 by an oil plug 12 outside the casing.
Lubricating oil is supplied via. Further, in the thrust bearing 4 which receives the thrust force generated in the impeller 1 via the spacer 16, the fixing member 14 is provided with the snap ring 15 to the casing flange portion 6 integrated with the turbine housing 17 and the casing of the speed increasing device. It is fixed and transmits the thrust force to the casing flange portion 6. Reference numeral 9 is a piston ring that prevents the lubricating oil from flowing to the impeller side.

In the present invention, the cooling air is passed through the end surface of the bearing holder 7 which is the sub-assembly of the sun gear shaft 13 which is the rotating shaft of the impeller 1 and which is sub-assembled through the floating bush 5 which can withstand the sun gear shaft 13 at an extremely high speed. A labyrinth seal 8 which is an air seal installed in a passage for sending from the pores 3 to the rear air chamber 18 of the impeller 1 is fixed in advance. By doing so, even if the impeller 1 is assembled in the apparatus and the thrust bearing 4 is loosened and the mounting error of the bearing holder 7 with respect to the casing flange portion 6, that is, the assembly error of the rotary shaft of the impeller 1 occurs, the bearing Since the holder 7, the labyrinth seal 8 and the impeller 1 do not change their relative positions in the axial direction, the labyrinth gap between the labyrinth seal 8 and the back surface of the impeller 1 set appropriately should always be maintained properly. become. Therefore, during the operation of the centrifugal supercharger, the impeller 1 pressurizes the air in the axial intake passage, which is sent from the air cleaner (not shown) through the intake pipe, by the radial centrifugal force to move the air in the circumferential direction from the radial passage. At the time of pressurizing the pressurizing volute 2 with high pressure, the negative pressure of the back air chamber 18 of the impeller 1 is always maintained appropriately, so that the impeller 1 is appropriately cooled and a proper labyrinth sealing performance is exhibited. The lubricating oil does not leak into the space 19 between the piston ring 9 and the labyrinth seal 8.

While one embodiment of the present invention has been described above, the fitting configuration of the casing flange portion and the bearing holder, the related configuration of the bearing holder and the labyrinth seal, and the labyrinth seal are within the scope of the gist of the present invention. It is needless to say that an appropriate combination can be adopted for the shape, the shape of the thrust bearing, the configuration related to the casing flange portion, the shape of the vent hole, and the like.

[0013]

As described in detail above, the present invention provides
Centrifugal air compressor that presses air in the axial intake passage with radial centrifugal force by an impeller that rotates by receiving power from the engine crankshaft via a speed increasing device and discharges it from a circumferential pressure volute. In a centrifugal supercharger, the labyrinth seal, which is an air seal installed in a passage for sending cooling air from a ventilation hole to a rear air chamber of an impeller, is mounted on a sun gear shaft that is a rotary shaft of the impeller. Since it is fixed to the end surface of the bearing holder that is sub-assembled to the shaft, the impeller is assembled in the device, and the thrust bearing is loosened, which may cause an error in mounting the bearing holder to the casing flange, that is, an error in assembling the rotary shaft of the impeller. Even if it occurs, the bearing holder, labyrinth seal and Impeller since no relationship position in the axial direction is changed, the labyrinth gap between the appropriately configured back of the labyrinth seal and the impeller will always be appropriately maintained. Further, in the present invention, the bearing holder is press-fitted into the casing flange portion by shrink fitting, etc., but at a step formed between the casing flange portion and the bearing holder that absorbs the thrust force generated during operation of the impeller, Unlike the conventional one, it is not necessary to interpose a shim or the like for adjusting in consideration of the labyrinth gap between the labyrinth seal and the back surface of the impeller, and it suffices to contact the stepped portion as it is, which requires labor for assembly. There is no need for labyrinth clearance control when installing the impeller. Moreover, since the labyrinth seal is installed on the end surface of the small-diameter bearing holder that is press-fitted into the inner circumference of the casing flange, the diameter can be made smaller than that of the conventional one, thus reducing the weight and reducing the cost. Since the area to be sealed is small, the sealing performance as a labyrinth seal is improved and the reliability is high.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a first embodiment of a centrifugal supercharger of the present invention.

FIG. 2 is a diagram showing a first example of a conventional centrifugal supercharger.

FIG. 3 is a diagram showing a second example of a conventional centrifugal supercharger.

[Explanation of symbols]

 1 Impeller 2 Pressurizing Volute 3 Vent 4 Thrust Bearing 6 Casing Flange 7 Bearing Holder 8 Labyrinth Seal 13 Sun Gear Shaft 18 Rear Air Chamber

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Claims (2)

[Claims] Claim: What is claimed is: 1. An impeller, which is rotated by receiving power from a crankshaft of an engine through a speed increasing device, pressurizes air in an axial intake passage by centrifugal force in a radial direction and discharges the air from a pressure volute in a circumferential direction. In a centrifugal supercharger consisting of a centrifugal air compressor, a labyrinth seal, which is an air seal installed in a passage that sends cooling air from a ventilation hole to a rear air chamber of an impeller, and a sun gear shaft, which is a rotating shaft of the impeller, are used as shafts. A centrifugal supercharger characterized by being fixed to an end surface of a bearing holder which is sub-assembled to the sun gear shaft for supporting. 2. The centrifugal supercharger according to claim 1, wherein the bearing holder is press-fitted into a casing flange portion.