CN215633947U

CN215633947U - Gas sealing device for air compressor and air compressor

Info

Publication number: CN215633947U
Application number: CN202122245342.8U
Authority: CN
Inventors: 陈霍; 陆秋琰
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2021-09-16
Filing date: 2021-09-16
Publication date: 2022-01-25
Anticipated expiration: 2031-09-16

Abstract

The utility model relates to a gas seal for an air compressor, comprising a sealing section of a defined length for sealing purposes, which is located between an impeller shaft of the air compressor and an impeller disk of the air compressor, on which sealing section at least one groove for sealing compressed air along the impeller shaft is formed, which compressed air reaches the groove via a gap between the impeller and the impeller disk, at least one of the grooves being designed at least on the basis of the product of the width and the depth of the respective groove as a variable, wherein the variable is greater than a predetermined threshold value. By optimally setting the gas seal, in particular taking into account the number of grooves, the product of the groove width and the depth of the gas seal as a design variable, the sealing effect against compressed air can be advantageously increased without the length of the sealing section being able to be changed and the costs for producing the gas seal can be reduced.

Description

Gas sealing device for air compressor and air compressor

Technical Field

The present invention relates to a gas seal for an air compressor, in particular for a fuel cell air compressor. The utility model also relates to an impeller disc comprising such a gas sealing device. The utility model further relates to an air compressor comprising such a gas seal or such an impeller disk.

Background

In an air compressor, air from the environment is supplied to a compressor wheel via an air compressor inlet, compressed to a high pressure by high speed rotation of the wheel and delivered to a compressor outlet. Since the compressed air is under high pressure inside the compressor and is supplied from the impeller shaft and the impeller disk via the gap between them, it often occurs that the compressed air leaks along the leakage gap from the high-pressure region to the low-pressure region, whereby the pressure of the compressed air and the supply of the compressed air are reduced, which in turn adversely affects the reliable operation of the air compressor.

In the prior art, sealing devices, in particular non-contact sealing devices, are provided in air compressors. The outer periphery of the impeller shaft is provided with a plurality of annular sealing teeth or grooves which are arranged in sequence, each groove forms a series of throttling gaps and expansion cavities and thus forms a labyrinth structure, and the sealed gas medium generates a throttling effect when flowing through the zigzag labyrinth gaps and generates energy conversion to seal the gas medium so as to achieve the purpose of preventing leakage.

In the conventional recognition, the larger the number of grooves of the labyrinth seal device, the better the sealing effect. However, on the one hand, the machining of these grooves requires high machining costs and, on the other hand, these grooves themselves also cause a reduction in the structural strength of the entire sealing device.

Therefore, there is a need for an improved gas sealing device which further improves the sealing against compressed air with a reduced number of grooves.

SUMMERY OF THE UTILITY MODEL

Against this background, according to one aspect of the utility model, a gas seal for an air compressor is proposed, which comprises a sealing section of a defined length for sealing purposes, which is located between an impeller shaft of the air compressor and an impeller disk of the air compressor, on which sealing section at least one groove for sealing compressed air along the impeller shaft is formed, the compressed air reaching the groove via a gap between the impeller and the impeller disk, at least one of the grooves being designed at least on the basis of the product of the width and the depth of the respective groove as a variable, wherein the variable is greater than a predetermined threshold value. Thus, the gas sealing device of the present invention can advantageously solve the above-described technical problems without increasing costs, so that the air compressor can be operated efficiently and reliably.

The basic idea of the utility model is that by optimally setting the gas seal, in particular taking into account the number of grooves, the product of the groove width and the depth of the gas seal as a design variable, the sealing effect against compressed air can be advantageously increased without the length of the sealing section being able to be changed and the costs for producing the gas seal can be reduced. In this case, the vortex formed by the compressed air in the groove is increased, so that a high flow resistance is produced to reduce the leakage of the compressed air into the low-pressure region. By the scheme of the utility model, the sealing performance of the air compressor can be improved under the condition of not increasing additional structural parts or materials, the operation reliability of the air compressor can be further improved, and the cost of the whole air compressor can be reduced.

The utility model is further developed from the individual embodiments that can be selected.

According to one embodiment of the utility model, the sealing section is formed with two grooves, which are formed adjacent to each other. The number of grooves is reduced in this embodiment. Contrary to the general knowledge that the greater the number of grooves, the better the sealing of the labyrinth seal, the rational dimensioning of the grooves by reducing the number of grooves enables the compressed air to generate large vortices in the grooves when flowing through the grooves, the formation of which vortices advantageously reduces the energy of the compressed air and thus improves the sealing of the compressed air.

According to an alternative embodiment of the utility model, the grooves are each greater than 2.9mm wide and greater than 4mm deep, wherein the predetermined threshold is 11.6mm². By reducing the number of grooves and increasing the number of grooves accordinglyThe leakage, for example, decreases to less than 1.62g/s with the width and depth of the large groove.

According to an alternative embodiment of the utility model, the sealing section is formed with only one groove. According to another alternative embodiment of the utility model, the groove has a width greater than 6.4mm and a depth greater than 4mm, wherein the predetermined threshold is 25.6mm². In this embodiment, the width of only one groove is significantly greater. As a result, the compressed air, when flowing through the recess, generates a greater turbulence in the recess, and by optimally dimensioning the recess, the tightness of the entire gas seal can be further increased even in the case of only one recess. Here, the leakage amount is reduced to less than 1.61 g/s. Furthermore, since only one groove is provided, the machining of the gas seal is greatly simplified and thus the manufacturing costs are reduced.

According to a further alternative embodiment of the utility model, the sealing section is arranged on a step of the impeller shaft configured as a stepped shaft, wherein an adjusting shim for adjusting a gap between the sealing section and the step is arranged between the sealing section and the step. Here, the steps of the impeller shaft and the outer circumferential surface of the adjusting shim together form a sealing fit with the sealing section. By providing corresponding adjusting shims, the gap of the sealing engagement can be adjusted or reduced, thereby further increasing the tightness against compressed air.

According to another alternative embodiment of the utility model, the gas sealing means is constructed on the impeller disc. That is, the gas sealing means is constructed integrally with the impeller disc. Here, the grooves are configured at the inner circumferential surface of the impeller disc. The grooves on the inner circumferential surface of the impeller disk thereby form a sealing engagement or a labyrinth seal with the outer circumferential surface of the impeller shaft and, if appropriate, with the outer circumferential surface of the adjusting shim.

According to an alternative embodiment of the utility model, the groove is manufactured by milling or stamping or casting. The grooves can be produced in a known production method.

According to another aspect of the present invention, there is provided an impeller disc for an air compressor, the impeller disc comprising a gas sealing arrangement as described above.

According to a further aspect of the present invention there is provided an air compressor comprising an impeller disc comprising a gas seal arrangement as described above.

Further features of the utility model will be apparent from the claims, the drawings and the description of the drawings. The features and feature combinations mentioned in the above description and those mentioned in the following description of the figures and/or shown in the figures only can be used not only in the respectively specified combination but also in other combinations without departing from the scope of the utility model. Accordingly, the following is also considered to be covered and disclosed by the present invention: these items are not explicitly shown in the drawings and are not explicitly explained, but originate from and result from combinations of separate features from the explained items. The following matters and combinations of features are also to be regarded as disclosed: which does not have all the features of the original written independent claim. Furthermore, the following and combinations of features are considered to be disclosed inter alia by the above: which exceed or deviate from the combinations of features defined in the claims' reference relations.

Drawings

Further optional details and features of the utility model result from the following description of preferred embodiments, which are schematically illustrated in the drawings. In this case, the amount of the solvent to be used,

fig. 1 shows a schematic structure of an air compressor according to an exemplary embodiment of the present invention;

FIG. 2 shows a schematic cross-sectional view of a gas sealing device according to an exemplary embodiment of the present invention;

FIG. 3 illustrates a cross-sectional view of a gas seal apparatus according to an exemplary embodiment of the present invention;

fig. 4 shows a cross-sectional view of a gas sealing device according to another exemplary embodiment of the present invention.

List of reference numerals

1 gas seal device

2 impeller

3 impeller plate

4 impeller shaft

5 air inlet

6 compressor shell

7 air compressor

8 grooves

9 adjusting shim

H depth

Width W

A high pressure region

B a low-pressure area.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and exemplary embodiments. It should be understood that the detailed description and specific examples, while indicating the scope of the utility model, are intended for purposes of illustration only.

A schematic structure of an air compressor 7 according to an exemplary embodiment of the present invention is shown in fig. 1. In this exemplary embodiment, the air compressor 7 includes: a compressor housing 6; an air inlet 5 arranged on the compressor housing 6; an impeller 2; the impeller 2 is arranged on the air inlet side; an impeller shaft 4, on which impeller shaft 4 the impeller 2 is arranged, which is configured as a stepped shaft by way of example; an impeller disk 3, said impeller disk 3 being arranged on said impeller shaft 4 adjacent to said impeller 2. Air from the environment enters the air compressor 7 via the air inlet 5 of the air compressor 7 and is compressed by the impeller 2 rotating at high speed. Here, gaps are present both between the impeller 2 and the impeller disk 3 and between the impeller disk 3 and the impeller shaft 4. In an ideal state where there is no leakage of the compressed air, the compressed air is delivered to the compressed air output side via a compressed air delivery passage (not shown in the drawings) provided in the compressor housing 6. However, in actual operation of the air compressor, the pressure at the left side of the impeller disk 3 (high pressure region a) is higher than the pressure at the right side of the impeller disk 3 (low pressure region B) as viewed in the direction of the paper shown in fig. 1, and therefore the compressed air reaches the impeller shaft 4 via the gap between the impeller 2 and the impeller disk 3 and flows toward the direction of the low pressure region B via the gap between the impeller shaft 4 and the impeller disk 3 due to the pressure difference between the left side of the impeller disk 3 and the right side of the impeller disk 3. Thereby, a leak path different from the compressed air delivery passage is formed in the air compressor 7 and thus leakage of the compressed air occurs. In order to reduce or prevent leakage of the compressed air, according to the exemplary embodiment, a gas sealing device 1 for preventing leakage of compressed air is also provided on the leakage path of compressed air.

In fig. 2 a schematic cross-sectional view of a gas sealing device 1 according to an exemplary embodiment of the present invention is shown. As can be seen from fig. 2, the gas seal 1 is formed according to this embodiment on the impeller disk 3 by way of example and comprises a sealing section which, as a result of the structural dimensioning of the impeller disk 3 in the axial direction, has a defined axial length and on which a plurality of grooves 8 are formed, which grooves 8 are formed at a distance from one another in the axial direction and thus form a labyrinth. In the exemplary embodiment, a spacer disk 9 is also provided, which spacer disk 9 is arranged on a shoulder of the impeller shaft 4 designed as a stepped shaft for adjusting the gap formed between the gas seal 1 or the seal segment and the impeller shaft 4/spacer disk 9. The adjusting shim 9 is designed in the form of a ring and is made, for example, of a metallic material or a material that is resistant to high temperatures and pressures. The gas sealing device 1 is arranged on a leakage path of compressed air from a high pressure region a in the direction of a low pressure region B, i.e. on a flow path via a gap between the impeller 2 and the impeller disc 3 and via a gap between the impeller disc 3 and the impeller shaft 4/shim plate 9, for sealing compressed air towards the low pressure region B.

In figure 3 is shown a device according to the utility modelA cross-sectional view of a gas sealing device 1 according to an exemplary embodiment of the utility model. In this exemplary embodiment, the gas seal 1, which is configured in an exemplary manner on the impeller disk 3, is configured with 2 grooves 8. At least one of the grooves 8 is designed based on the product of the width W and the depth H of the respective groove 8 as a variable Y. That is, at least one of the recesses 8 is formed according to the formula Y ═ f (W, H) ═ W × H, where Y is>And S, wherein S is a preset threshold value. Also in this exemplary embodiment, the two grooves 8 have an increased width W and depth H compared to the gas sealing device 1 of the prior art and both have the same width W and depth H, and have a width W of more than 2.95mm and a depth H of more than 4mm, wherein the predetermined threshold S is 11.6mm²Whereby Y is>And S. In this case, the leakage of compressed air is reduced to less than 1.62g/s during operation of the air compressor 7. Since the product Y of the width W and the depth H of each of the two grooves 8 is greater than the predetermined threshold S, the compressed air generates an increased vortex when flowing through the grooves 8. The increased turbulence in the groove 8 can lead to an increased energy dissipation or energy conversion of the compressed air and thus to an increased flow resistance, which advantageously contributes to the sealing of the compressed air. Thus, contrary to general knowledge, an improved tightness of the gas sealing device 1 is achieved in contrast to a reduction in the number of grooves 8.

Fig. 4 shows a sectional view of a gas sealing device 1 according to a further exemplary embodiment of the present invention. As can be seen from fig. 4, the gas sealing device 1 in fig. 4 has only one recess 8. Similar to the embodiment of fig. 3, the only one groove 8 is designed on the basis of its product of width W and depth H as variable Y. That is, the single recess 8 is formed according to the formula Y (f (W, H) W × H, Y being>And S, wherein S is a preset threshold value. In this exemplary embodiment, the only one groove 8 has a width W of more than 6.4mm and a depth H of more than 4mm, wherein the predetermined threshold value S is exemplarily 25.6mm²Whereby Y is>And S. Now, in comparison with the gas seal 1 according to fig. 3, the width W of the single groove 8 is significantly greater thanThe width W of each groove 8 of the gas sealing device 1 in fig. 3. With this optimized configuration of the gas sealing arrangement 1, the leakage of compressed air is further reduced to at least less than 1.61g/s during operation of the air compressor 7.

In the present invention, the predetermined threshold S is not fixed but is related to the design capacity of the air compressor and the maximum pressure of the compressed air, the specific configuration of the air compressor, and the like and may be set by simulation and testing based on the operating condition of the air compressor and the sealing section length.

In the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. Other advantages and alternative embodiments of the present invention will be apparent to those skilled in the art. Therefore, the utility model in its broader aspects is not limited to the specific details, representative structures, and illustrative examples shown and described. On the contrary, various modifications and substitutions may be made by those skilled in the art without departing from the basic spirit and scope of the utility model.

Claims

1. A gas seal (1) for an air compressor (7), the gas seal (1) comprises a sealing section of a defined length for sealing purposes, the sealing section is located between an impeller shaft (4) of the air compressor (7) and an impeller disc (3) of the air compressor (7), at least one groove (8) for sealing compressed air along the impeller shaft (4) is formed on the sealing section, the compressed air reaches the grooves (8) via a gap between the impeller (2) and the impeller disk (3), at least one of the grooves (8) is designed as a variable (Y) at least on the basis of the product of the width (W) and the depth (H) of the respective groove (8), wherein the variable (Y) is greater than a predetermined threshold value (S).

2. Gas sealing device (1) for an air compressor (7) according to claim 1, characterized in that the sealing section is configured with two grooves (8), the two grooves (8) being configured adjacently.

3. Gas sealing device (1) for an air compressor (7) according to claim 1, characterized in that the sealing section is configured with only one groove (8).

4. Gas sealing device (1) for an air compressor (7) according to claim 2, characterized in that the grooves (8) each have a width (W) greater than 2.9mm and a depth (H) greater than 4mm, wherein the predetermined threshold value (S) is 11.6mm²。

5. Gas sealing device (1) for an air compressor (7) according to claim 3, characterized in that the groove (8) has a width (W) greater than 6.4mm and a depth (H) greater than 4mm, wherein the predetermined threshold value (S) is 25.6mm²。

6. The gas sealing device (1) for an air compressor (7) according to one of claims 1 to 5, characterized in that the sealing section is arranged on a step of the impeller shaft (4) configured as a stepped shaft, wherein a shim (9) for adjusting a gap between the sealing section and the step is arranged between the sealing section and the step.

7. Gas sealing device (1) for an air compressor (7) according to one of claims 1 to 5, characterized in that the gas sealing device (1) is constructed on the impeller disc (3).

8. Gas sealing device (1) for an air compressor (7) according to one of claims 1 to 5, characterized in that the groove is manufactured by milling or stamping or casting.

9. Impeller disc (3) for an air compressor, characterized in that the impeller disc (3) comprises a gas sealing device (1) according to one of claims 1 to 8.

10. An air compressor (7), characterized in that the air compressor (7) comprises an impeller disc (3) according to claim 9.