KR20080059352A - Variable diffuser and compressor - Google Patents

Abstract

A variable diffuser for a compressor, having further increased efficiency. In the variable diffuser (30), a diffuser passage (33) for recovering static pressure from dynamic pressure by reducing the speed of an air current discharged from the outer peripheral end of an impeller rotating in a housing is formed between a hub-side wall surface (32a) and a shroud-side wall surface (31a), and diffuser vanes are installed in the diffuser passage (33). Fixed vanes (35) and movable vanes (34) serving as the diffuser vanes are alternately circumferentially fixed to a fixed disk (32) and a movable disk (31) that form the hub-side wall surface (32a) and the shroud-side wall surface (31a). The variable diffuser also has a drive device (40) for rotating the movable disk (31) coaxially with the impeller.

Description

Variable Diffusers and Compressors {VARIABLE DIFFUSER AND COMPRESSOR}

TECHNICAL FIELD This invention relates to the variable diffuser applied to a centrifugal compressor, a four-flow compressor, etc., and the compressor provided with this variable diffuser, for example.

Conventionally, centrifugal compressors, such as a turbocharger used for the internal combustion engine for automobiles, are known.

Fig. 17 is a sectional view showing the main part of a conventional centrifugal compressor. In the illustrated centrifugal compressor 10, the impeller 13 including the plurality of blades 12 rotates in the housing 11, thereby compressing a fluid such as gas or air introduced from the outside of the housing 11. The flow (airflow) of the fluid thus formed is transferred to the outside through an impeller outlet (hereinafter also referred to as a "diffuser inlet") 14, a diffuser 15, and scrolls (not shown), which serve as outer peripheral ends of the impeller 13. It is sent out. In addition, the code | symbol 16 is a shaft center line which the impeller 13 rotates in the figure.

The diffuser 15 described above is a passage of airflow provided between the impeller outlet 14 and the scroll, and has a function of restoring dynamic pressure to a constant pressure by decelerating the airflow discharged from the impeller outlet 14. The diffuser 15 is usually formed of a pair of opposing wall surfaces, and in the following description, one side of the opposing pair of wall surfaces is called a shroud side wall surface 17, and the other is a hub side wall surface 18. It is called.

The diffuser 15 described above includes, for example, a vane diffuser provided with a diffuser blade (hereinafter referred to as "vane") 19 as shown in FIG. 18, and a vaneless having no vane 19. There is a diffuser.

In the general centrifugal compressor provided with the vane diffuser, the vane 19 employs a fixed blade diffuser with floating. However, when the flow rate range of the centrifugal compressor is required, the vane 19 is operated to change the blade front edge angle βk (hereinafter referred to as “blade angle βk”) shown in FIG. 20. A variable diffuser that can be used is adopted.

The general structure of the variable diffuser is that, for example, as shown in Fig. 18, a pivot shaft 20 is provided on the vanes 19 to support the shroud side wall surface 17 and the hub side wall surface 18, and at the same time, the pivot is provided. The vane 19 is rotated about the axis 20 to change the blade angle βk.

For such a variable diffuser, a drive device is proposed in which the angles of a plurality of diffuser blades are varied with a simple structure. This drive device is equipped with the gear wheel which rotates by an actuator etc., and the some gear meshed with a gear wheel, and rotates the diffuser blade connected to each gear, and changes an angle (for example, refer patent document 1). .

Moreover, in the centrifugal compressor provided with the diffuser with a blade, it is proposed to provide the 2nd stationary blade which can be rotated for the purpose of expanding the operation of the low flow rate side (for example, patent documents 2, 3). Reference).

Patent Document 1: Japanese Patent Application Laid-open No. Hei 7-310697

Patent Document 2: Japanese Patent Application No. 2865834

Patent Document 3: Japanese Patent Application No. 3513729

By the way, about the vane 19 of a variable diffuser, when designing a vane blade shape, it sets to the shape which becomes intermediate in the desired flow rate change range. Therefore, in the conventional variable diffuser in which the vane 19 is rotated about the pivot shaft 20 to make the blade angle beta k variable, the characteristic change as shown in FIG. 19 occurs. That is, the flow rate range defined by the surge flow rate Qs and the choke flow rate Qc is, for example, as shown in Fig. 20, the vane 19 is moved from the maximum blade angle βmax to the minimum blade angle βmin. By rotating in the range of rotation range (theta), it becomes large enough by the variation of the surge flow volume Qs and the choke flow volume Qc corresponding to each.

However, in the case where the above-described flow rate range (range where the flow rate can be changed) is set to be greatly widened, as shown in Fig. 21, the change of the inclination of the flow angle β and the blade angle βk of the vane 19 is different. Achieve. For this reason, since the range In becomes large in the low flow rate region and the large flow rate region, there is a problem that the efficiency decreases due to the increase of the loss. Also, the range is a value defined by the difference between the blade front edge angle βk and the flow angle β.

In addition, the rotary variable diffuser structure allows a gap δ between both ends of the vanes 19 and the shroud side wall surface 17 and the hub side wall surface 18 (Fig. 18) to enable smooth rotation of the vanes 19. Is formed). For this reason, since the leak of the airflow which flows through the clearance gap (delta) arises, the problem that efficiency falls over the whole flow volume range is also pointed out.

As described above, the conventional variable diffuser has a problem that the efficiency decreases due to the increase in the range or leakage from the gap δ. Therefore, it is expected to solve this problem and improve the efficiency further.

This invention is made | formed in view of the said situation, Comprising: It aims at providing the variable diffuser which can improve efficiency, and the compressor provided with this variable diffuser.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention employ | adopted the following means.

In the variable diffuser according to the present invention, a diffuser passage is formed between the hub side wall and the shroud side wall surface to reduce the airflow discharged from the outer peripheral end of the impeller rotating in the housing, thereby restoring the dynamic pressure to the static pressure, and the diffuser blade in the diffuser passage. In the variable diffuser provided with, the said diffuser blade is alternately fixed to the wall member which forms the said hub side wall surface and the shroud side wall surface in the circumferential direction, and any one of the said wall surface members is coaxial with rotation of the said impeller. It is characterized in that the drive means for rotating the rotation is provided.

According to such a variable diffuser, a drive means for alternately fixing the diffuser blades in the circumferential direction to the wall members forming the hub side wall and the shroud side wall, and rotating one of the wall members coaxially with the rotation of the impeller is provided. Thus, by rotating the wall member on the movable side, the throat area can be changed without changing the blade front edge angle. Further, the gap δ formed between the diffuser blade and the hub side wall surface and the shroud side wall surface is reduced because it is only one surface.

In this case, it is preferable that the movable range of the said wall surface member rotated by the said drive means is set so that it may be fixed to the wall surface member of a fixed side, and spans the full width between adjacent diffuser blades.

In the above invention, the inlet radius R1 of the diffuser blade provided on the rotating side of the wall member is set larger than the inlet radius R2 of the diffuser blade provided on the fixed side of the wall member (R1 > R2). It is preferable to be present, whereby it is possible to prevent the thickness of the front edge of the overlapping blades from increasing.

In the above invention, the blade front edge angle αk1 of the diffuser blade provided on the rotating side of the wall member is the blade front edge angle αk2 of the diffuser blade installed on the fixed side of the wall member at the same radial position. It is preferable to set smaller ((alpha) k1 <(alpha) k2), and it can reduce the average blade front edge angle in the state which two blades overlapped by this.

In the above invention, the blade front edge angle αk1 of the diffuser blade provided on the rotating side of the wall member is the blade front edge angle αk2 of the diffuser blade installed on the fixed side of the wall member at the same radial position. It is preferable to set larger ((alpha) k1> (alpha) k2), and it can increase the average blade front edge angle in the state which two blades overlapped by this.

In the above invention, it is preferable that the diffuser blade provided on the fixed side of the wall member is a small ratio ratio blade, thereby improving the characteristics at low flow rate while maintaining the characteristics of the small ratio ratio blade. Can be.

In this case, the rear corner radius R3 of the diffuser blade provided on the rotating side of the wall member is set larger than the rear corner radius R4 of the diffuser blade installed on the fixed side of the wall member (R3 &gt; R4). It is preferable to achieve a wide range of the flow rate range and a high pressure ratio by this.

In the above invention, the setting of the fixed side and the rotating side may be reversed.

That is, the inlet radius R2 of the diffuser blade provided on the fixed side of the wall member may be set larger than the inlet radius R1 of the diffuser blade provided on the rotational side of the wall member (R2> R1).

Further, the blade front edge angle αk2 of the diffuser blade provided on the fixed side of the wall member is smaller than the blade front edge angle αk1 of the diffuser blade provided on the rotation side of the wall member at the same radial position (αk2 <αk1). ) May be set.

In addition, the diffuser blade provided on the rotation side of the wall member may be a small ratio blade.

The rear corner radius R4 of the diffuser blade provided on the fixed side of the wall member may be set larger than the rear corner radius R3 of the diffuser blade provided on the rotational side of the wall member (R4> R3).

In the above-mentioned invention, it is preferable that the driving means has a sliding mechanism portion for reciprocating the gap between the gap formation position and the gap reduction position with respect to the fixed side of the wall member. As a result, the gap δ can be minimized to improve the efficiency.

The compressor which concerns on this invention is provided with the variable diffuser of any one of Claims 1-9 in the outer peripheral end part of the impeller rotating in a housing.

According to such a compressor, it becomes the compressor provided with the variable diffuser which can enlarge the range and eliminate the efficiency fall by the leakage from the clearance gap (delta), and can improve further efficiency.

According to the present invention described above, since the throat area can be changed without changing the angle of the front edge of the blade on the movable side, the decrease in efficiency due to the increase in the range can be eliminated, and thus the variable diffuser with improved efficiency and the It is possible to provide a compressor having a variable diffuser.

In addition, since the gap δ formed between the diffuser blade and the hub side wall surface and the shroud side wall surface is reduced to only one surface, it is possible to eliminate the decrease in efficiency due to leakage from the gap δ.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment which concerns on the variable diffuser of this invention, (a) is an exploded perspective view of a principal part, (b) is A-A sectional drawing of (a).

2 is a view showing the operation of the variable diffuser shown in FIG. 1, where (a) is set to A11 = A12, (b) is a state where the movable blade is in contact with the pressure surface of the fixed blade, and (c) is It is a figure which shows the case where it sets in the middle of (a) and (b).

Fig. 3 is a view showing the operation of the variable diffuser according to the second embodiment of the present invention. (A) When the movable blade inlet radius is larger than the fixed blade, (b) is the intersection of the front edge of the movable blade. When it rotates in the upstream of (X), (c) is a figure which shows the case where the front edge of a movable blade rotated downstream of intersection X. In FIG.

4 is a diagram showing a variable diffuser according to a third embodiment of the present invention.

FIG. 5 is a view showing characteristics of the variable diffuser shown in FIG. 4.

Fig. 6 is a diagram showing a variable diffuser according to a fourth embodiment of the present invention.

FIG. 7 is a view showing characteristics of the variable diffuser shown in FIG.

8 is a diagram showing a variable diffuser according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing a modification of the variable diffuser according to the fifth embodiment shown in FIG. 8.

Fig. 10 is a graph showing the relationship between the pressure recovery rate and the number of blades for the vane diffuser and the small-noise ratio diffuser.

11 is a perspective view of an essential part showing a variable diffuser according to a sixth embodiment of the present invention.

Fig. 12 is an explanatory view of the sliding mechanism portion shown in Fig. 11, (a) is a view showing the operation of the sliding surface relative to the guide surface, and (b) is a gap δ which changes with the rotation of the movable disc. It is a figure which shows.

FIG. 13 is a view showing a state of the movable disc and the movable blade which are moved by the sliding mechanism shown in FIG.

Fig. 14 is a sectional view showing a configuration example in which an active surface is provided on a wall between the movable blade and the fixed blade.

FIG. 15 is a diagram showing a first modification of the sliding mechanism part shown in FIG.

FIG. 16 is a view showing a second modified example of the sliding mechanism part shown in FIG.

Fig. 17 is a sectional view showing the main part of a conventional centrifugal compressor.

18 is a perspective view of an essential part showing a conventional example of an annular variable diffuser.

FIG. 19 is a diagram showing the characteristics of the variable diffuser shown in FIG.

20 is an explanatory diagram showing the operation of the variable diffuser shown in FIG.

Fig. 21 is a diagram showing the relationship between the range In, the flow angle β, and the blade angle βk.

<Description of the code>

30: variable diffuser

31: movable disc

31a: Shroud side wall

32: fixed disc

32a: hub side wall

33: diffuser passage

34, 34A to E: movable diffuser blades (movable blades)

35: fixed diffuser blade (fixed blade)

40, 40A: drive unit

41: gear drive unit

42: rack gear

43: pinion gear

45, 45A: sliding mechanism

46: guide rail

47: concave groove

48: guide groove

48a: guide surface

49: convex part

49a: sliding surface

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of the variable diffuser and the compressor which concerns on this invention are described based on drawing.

<1st embodiment>

The variable diffuser 30 shown in FIG. 1 recovers the dynamic pressure of the airflow to a constant pressure by decelerating the airflow discharged from the outer peripheral end of the impeller rotating in a housing such as a centrifugal compressor or a four-flow compressor. The variable diffuser 30 has a diffuser passage 33 formed between the opposing shroud side wall surface 31a and the hub side wall surface 32a, and a movable diffuser blade (hereinafter referred to as a "moving blade") in the diffuser passage 33. 34 and fixed diffuser blades (hereinafter referred to as "fixed blades") 35 are provided.

In addition, although the movable blade 34 is provided and movable in the shroud side wall surface 31a here, you may make it movable by providing the movable blade 34 in the hub side wall surface 32a.

The configuration of the movable diffuser 30 will be described in detail, and the movable blade 34 is fixed to the movable disc (wall member) 31 forming the shroud side wall surface 31a, and the fixed blade 35 is attached to the hub side wall surface ( It is fixed to the fixed disk (wall surface member) 32 which forms 32a). The movable blade 34 and the fixed blade 35 have the same blade shape, and the same number of blades (blade number N) is the circumferential direction with respect to the shroud side wall surface 31a and the hub side wall surface 32a, respectively. It is arranged at a predetermined pitch.

Fig. 1A shows a state in which a pair of opposing movable discs 31 and fixed discs 32 are separated. From this state, the movable disk 31 and the fixed disk 32 have the movable blade 34 of the shroud side wall surface 31a and the fixed blade 35 of the hub side wall surface 32a in the circumferential direction at a predetermined reference position. The slides are integrated in a combination direction indicated by arrows in the drawing so as to be alternately arranged at equal pitches. That is, in the assembled state in which the movable original plate 31 and the fixed original plate 32 are integrated, the movable blade 31 and the fixed blade 32 are arranged at equal pitch alternately in the circumferential direction at a predetermined reference position. 1B is a cross-sectional view taken along line A-A of FIG. 1A with respect to the diffuser passage 33 formed by integrating the movable original plate 31 and the stationary original plate 32.

On the movable disc 31 side, a drive device 40 is provided for rotating the movable disc 31 in a direction of rotation of the impeller and coaxial rotation (indicated by a white arrow in the figure), to rotate a predetermined rotation range θ. have. This drive device 40 is comprised by the gear drive part 41 provided in the upper end part of the movable original plate 31, and the sliding mechanism part 45 provided in the lower end part, for example. The rotation range θ in this case is substantially different from the pitch of the blades in comparison with the pitches in which the movable blades 31 and the fixed blades 32 are alternately arranged in the circumferential direction at the predetermined reference positions described above, but substantially Approximately doubled. In other words, the movable range θ is the entire width between the blades of the adjacent fixed blades 35.

The gear drive part 41 becomes a structure which meshes the rack gear part 42 and the pinion gear 43 which were formed in the upper end surface of the movable original plate 31. As shown in FIG. In addition, the pinion gear 43 is connected to a drive source such as an electric motor (not shown), and can be rotated in a desired direction as necessary.

The sliding mechanism part 45 is a part in which the movable original plate 31 is slidably connected to the circumferential direction with respect to the housing 11. In the example shown, the convex guide rail 46 formed in the housing 11 and the recessed groove part 47 formed in the lower end surface of the movable disc 31 are fitted, and the movable disc 31 is the guide rail 46. It is configured to slide along. Such a sliding mechanism part 45 is a guide rail so that the high-pressure airflow which restored the static pressure at the exit of the diffuser passage 33 does not leak from the back surface of the movable disc 31 to the inlet side of the diffuser passage 33. Between the 46 and the recessed groove part 47, the leak prevention measures which are not shown are implemented.

As a result, the movable disc 31 is guided to the sliding mechanism part 45 by rotating the pinion gear 43 of the gear drive part 41 and rotates coaxially with the axis of rotation of the impeller, so that the fixed disc 32 is floating. Move relative to. Then, the movable master plate 31 and the movable blade 34 integrally move from the reference position to both sides in the circumferential direction within the range of the movable range θ. That is, the movable blade 34 is moved toward the fixed blades 35 on both sides adjacent to each other by rotating from the reference positions arranged at equal pitches, and as shown by the imaginary line in FIG. Without changing the angle of the blade from the position where the pressure surface is in contact with the negative pressure surface of the adjacent fixed blade 35 to the position where the negative pressure surface of the movable blade 34 is in contact with the pressure surface of the adjacent fixed blade 35, It becomes rotatable in the range of the movable range (theta).

The movable range θ of the movable blade 34 will be described in more detail based on FIG. 2.

2 (a) shows a case where the movable blade 34 is at the reference position. In this state, the movable blade 34 and the fixed blade 35 which have the same blade shape are arranged in equal pitch (N sheets) in the circumferential direction, respectively. In this state, the throats A11 and A12 formed between the blades and the fixed blade 35 adjacent to both sides of the movable blade 34 become equal. For this reason, the throat area of the variable diffuser 30 is a value obtained by multiplying the number N of the movable blades 34 by the total value A11 + A12 of the throats formed on both sides of the movable blades 34.

2B shows a state in which the movable blade 34 is in contact with the pressure surface of the fixed blade 35. In this state, since the blades are in contact with each other, the throat A12 becomes approximately 0, and the throat A11 becomes the maximum (A11max). And since this maximum throat becomes larger than the sum total of the throats in the above-mentioned reference position (A11max> A11 + A12), the throat area increases by 1.2 to 1.3 times. In the following description, the state where the throat area is maximized in this manner is referred to as the throat maximum position.

Also, even when the movable blade 34 is rotated in the opposite direction from the reference position, the two blades are not in contact with somewhere, which results in the same result.

FIG. 2C shows the case where the movable blade 34 is in the intermediate position between FIG. 2A and FIG. 2B. The throat area in this state is approximately halfway between the reference position and the throat maximum position. Therefore, by rotating the movable blade 34 in the range of the movable range (theta), the throat area can be suitably changed within the range of about 1.2 to 1.3 times the reference value.

In the variable diffuser 30 having the above-described configuration, the number of diffuser blades composed of the movable blade 34 and the fixed blade 35 is substantially doubled from N sheets to 2N sheets. That is, when N pieces of movable blades 34 are provided on the movable disc 31 and N pieces of fixed blades 35 are installed on the fixed disc 32, the movable blades 34 and the fixed blades 35 are fixed. ) Are spaced apart from each other there are 2N diffuser blades. However, in a state where the adjacent movable blade 34 and the fixed blade 35 are in contact with each other, the airflow substantially flows between the N diffuser blades.

As a result, the flow rate of the compressor characteristics changes in accordance with the change in the throat area. That is, since the throat area is increased by about 1.2 to 1.3 times, the flow rate range can be widened by changing the choke flow rate Qc shown in Fig. 19 by about 20 to 30%.

In addition, since the blade front edge angle (blade angle) β of the movable blade 34 as well as the fixed blade 35 is always constant, the conventional blade angle β is changed by the rotation of the vanes 19. Compared with the variable diffuser, the change in range becomes very small as indicated by the dashed-dotted line in FIG. Therefore, the compressor provided with this variable diffuser 30 can reduce the loss which increases when the range becomes large, and can improve efficiency compared with the former.

Moreover, since the one end of the movable blade 34 and the fixed blade 35 is being fixed to the wall surface which forms the diffuser passage 33, the clearance gap (delta) is formed only in one side of the blade width direction. Therefore, compared with the conventional structure which rotates the vane 19, since the area | region of the clearance gap (delta) can be reduced by half, the loss by the airflow leakage can be reduced by half, and efficiency can be improved.

<2nd embodiment>

Then, 2nd Embodiment of this invention is described based on FIG.

In the movable blade 34A of the present embodiment, the inlet radius R1 is set larger than the inlet radius R2 of the fixed blade 35. That is, the inlet radius R1 of the movable blade 34A is a throat between the blades formed by the adjacent fixed blades 35 when the movable blade 34A is at an intermediate position of the adjacent fixed blades 35. For (A2), the blade front edge of the movable blade 34A is set to be upstream. In the example shown, with respect to the intersection X of the throat A2 and the radius R1, the throat area changes only in a range where the front edge of the movable blade 34A is upstream of the throat A2.

Hereinafter, it demonstrates concretely based on drawing.

As shown in Fig. 3A, when the movable blade 34A is located approximately at the center of the fixed blade 35, the throat area is minimized.

As shown in Fig. 3B, when the front edge of the movable blade 34A is located upstream of the throat A2, the total value A11 + A12 of the throat A11 and the throat A12. ) Gradually increases.

As shown in Fig. 3C, when the front edge of the movable blade 34A is located downstream of the throat A2, the throat area is a value obtained by multiplying the throat A2 by the number of blades N. As a result, even when the movable blade 34A is rotated, the throat reaches the maximum A2 and does not increase.

By the way, in the above-described state of FIG. It becomes This increase in blade thickness is not only an obstacle to increasing the throat area to the maximum, but also increases the loss of the blade front edge.

However, in the state shown in Fig. 3C, the front edge of the movable blade 34A is located downstream of the front edge of the fixed blade 35. Therefore, compared with the state shown in FIG.2 (b), the magnitude | size of a throat becomes A2> A1 lmax. In this way, when the inlet radius R1 is set larger than the inlet radius R2 (R1 &gt; R2), the movable range of the throat area becomes large.

In addition, in the state shown in Fig. 3C, the blade front edge is substantially reduced to the number of sheets of the fixed blade 35, so that the loss of the blade front edge is reduced.

<Third embodiment>

Then, 3rd Embodiment of this invention is described based on FIG. 4 and FIG.

The movable blade 34B of the present embodiment sets the blade front edge angle (blade angle) αk1 to be smaller than the blade angle αk2 of the fixed blade 35 at the same radial position, and sets the movable blade 34B. It drives toward the negative pressure surface of the fixed blade 35 from the middle of the fixed blade 35.

With such a configuration, the maximum value of the throat A12 is smaller than that of the throat A2, but the average blade angle αk can be reduced in the state where two blades are overlapped.

As a result, the characteristics of the compressor show that the flow angle α at the maximum angle decreases as shown in Fig. 5, and the performance when the flow rate is small is improved from the comparison between the solid line display and the broken line display. Can be. Moreover, also in the intermediate angle, it is understood from the comparison between the solid line display and the dotted line display that the performance at a small flow rate with a small flow angle α is also improved, but not at the maximum angle.

In other words, setting the blade angle αk to αk1 <αk2 focuses on performance at low flow rate with small flow angle α, and improves the pressure ratio in the low flow rate region at the maximum angle and at the intermediate angle. Performance improvement can be achieved.

<4th embodiment>

Then, 4th Embodiment of this invention is described based on FIG. 6 and FIG.

In the movable blade 34C of the present embodiment, the blade front edge angle (blade angle) αk1 is set larger than the blade angle αk2 of the fixed blade 35 at the same radius position, and the movable blade 34C is set. Driving from the middle of the stationary blade 35 toward the pressure surface of the stationary blade 35.

With such a configuration, as in the second embodiment described above, the throat has the maximum value A2. On the other hand, the choke flow rate Qc becomes a larger angle with respect to the pressure surface angle of the fixed blade 35, because the flow angle α of the diffuser inlet flows approximately at right angles to the throat A2. For this reason, the range of negative becomes large and a loss is large and it becomes a cause of reducing a substantial choke flow volume.

However, in the present embodiment, the average blade angle αk can be increased in the state where the movable blade 34C and the fixed blade 35 are in contact with each other and the two blades are joined.

As a result, the characteristics of the compressor are improved in performance due to the increase in the pressure ratio from the comparison between the solid line display and the broken line display at a large flow rate when the flow angle α is large at the maximum angle as shown in FIG. It can be seen that. Moreover, also in the intermediate angle, it is understood from the comparison between the solid line display and the dotted line display that the performance at large flow rate with a large flow angle α is also improved, but not at the maximum angle.

In other words, setting the blade angle αk to αk1> αk2 focuses on performance at large flow rates with a large flow angle α, and at a maximum angle and at an intermediate angle, the pressure ratio in the large flow rate region. Performance improvement can be obtained.

<5th embodiment>

Subsequently, a fifth embodiment of the present invention will be described with reference to Figs.

In the vane diffuser, the shortest distance is not formed at right angles from the blade negative pressure surface between the adjacent blades, in other words, the throat cannot be throated. It is generally recognized. This small ratio diffuser has the following features.

Since the vaneless diffuser has a small surge flow rate Qs and a large choke flow rate Qc, the vaneless diffuser has a characteristic of having a wide flow rate range but low efficiency.

On the other hand, since the vane diffuser has a large surge flow rate Qs and the choke flow rate Qc is only about 10 to 20% larger than the surge flow rate Qs, the vane diffuser has a characteristic that the flow rate range is narrow but the efficiency is high.

On the other hand, since the small draw ratio diffuser cannot throat, the choke flow rate Qc is larger than the vane diffuser, and the surge flow rate Qs is larger than the vane diffuser. Therefore, the small cell ratio diffuser has a feature that the efficiency is higher than that of the vaneless diffuser. In addition, in the small draw ratio diffuser, the movable blade in which the throat is not formed is called "a small draw ratio blade".

Fig. 10 shows the relationship between the pressure recovery rate and the number of blades for the vane diffuser and the small particle ratio diffuser as characteristics of the diffuser.

When the number of blades is changed, the normal vane diffuser changes rapidly when the number of blades is small and the number of blades from about 10 pieces as shown by the solid line in the figure, and the pressure recovery rate rapidly decreases. do.

On the other hand, since the size of the blade itself is smaller than that of a conventional vane diffuser in the small particle ratio diffuser, even if the number of blades is increased as shown by the dashed-dotted line in the figure, the pressure recovery rate does not increase until the conventional vane diffuser.

Therefore, in the fifth embodiment, as shown in Fig. 8, in the small ratio ratio diffuser provided with a small ratio ratio blade which is small enough to form a throat, the number of the fixed blades 35 is reduced. A2) is set and the above-described second embodiment is applied.

That is, the movable blade 34D of this embodiment sets the inlet radius R1 larger than the inlet radius R2 of the fixed blade 35. Therefore, the inlet radius R1 of the movable blade 34D is virtual between the blades formed by the adjacent fixed blades 35 when the movable blade 34D is at an intermediate position of the adjacent fixed blades 35. With respect to the throat A2, the blade front edge of the movable blade 34D is set so that it may be an upstream side.

In such a configuration, when the movable blade 34D and the fixed blade 35 are stacked, the pressure recovery rate is the same as that of the N-small blade ratio blade, and when both blades are installed at equal intervals, the number of blades is 2N sheets. The recovery rate is high. Therefore, by adopting the configuration of the present embodiment, it is possible to improve the performance by setting the movable blade 34D and the fixed blade 35 at equal intervals at a low flow rate while maintaining the characteristics of the small draw ratio diffuser.

Next, the modification of this embodiment is shown in FIG. This modified example uses the fixed blade 35 as a small ratio blade as in the embodiment shown in FIG. 8, and the rear edge radius R3 of the movable blade 34E is the rear edge radius R4 of the fixed blade 35. It is set larger.

With such a configuration, the following characteristics can be obtained. That is, as shown in Fig. 9A, when the movable blade 34E and the fixed blade 35 are separated and the number of blades is 2N sheets, the blade area of the movable blade 34E is smaller than that of the small draw ratio diffuser. As it increases, the pressure recovery rate increases.

In addition, when the movable blade 34E is in the position shown in Fig. 9B, the characteristics of the wide range in which the throat is not formed are shown.

And when the movable blade 34E is in the position shown to Fig.9 (c), it shows the same high pressure recovery rate as the usual vane diffuser which made N pieces of blades.

For this reason, when the movable blade 34E is on the pressure surface side of the fixed blade 35 rather than the actual throat, the choke flow rate Qc and the surge flow rate Qs in order to function as the small-focal ratio blade. It is possible to obtain the effect of increasing the pressure rise by the movable blade 34E while maintaining the widening range in which the flow rate range defined by. Therefore, by adopting the configuration of the present embodiment, the performance can be improved by setting the movable blade 34E and the fixed blade 35 at equal intervals at a low flow rate while maintaining the characteristics of the small draw ratio diffuser. Expansion of the flow range) and the high pressure ratio can be achieved simultaneously.

<6th embodiment>

Subsequently, a sixth embodiment of the present invention will be described with reference to Figs.

This embodiment is related with the sliding mechanism part 45 of the drive device 40 which rotates the movable disc 31, and especially reduces the clearance gap (delta) between the wall surface of the stationary disc 32, and the movable blade 34. As shown in FIG. To a suitable structure.

The drive device 40A shown in FIG. 11 includes a sliding mechanism 45A formed by a guide groove 48 formed in the housing 11 and a convex portion 49 formed in the lower end of the movable disc 31. Equipped.

One side surface of the guide groove 48 is provided with a guide surface 48a having a concave-convex shape having a circular arc shape (radius R). Similarly, on the convex part 49 side, the sliding surface 49a which provided the unevenness | corrugation of the same circular arc shape (radius R) with respect to the side surface which opposes the guide surface 48a is provided. This sliding surface 49a is in contact with the guide surface 48a. As the movable disc 31 rotates, the arc-shaped uneven contact positions formed on both sides move in the circumferential direction.

In addition, the housing 11 is provided with a sealing member 50 which exerts a sealing function in contact with a surface which becomes the outer peripheral side of the movable original plate 31 when viewed from the diffuser passage 33 side. This sealing member 50 prevents the airflow which flows through the diffuser passage 33 from leaking through 45 A of sliding mechanism parts.

With such a configuration, the movable disc 31 moves in the direction approaching or spaced apart from the fixed disc 32 in accordance with the uneven contact position between the guide surface 48a and the sliding surface 49a. Change the distance between planes. This change in distance between planes will be described in detail with reference to FIGS. 12 and 13.

As for the movable original plate 31, when the movable original plate 31 side rotates, the clearance gap formation position which the convex part formed in the guide surface 48a of the fixed side and the convex part formed in the sliding surface 49a contact | connects (FIG. 12 (a)). Between the gap reduction position (indicated by a solid line in Fig. 12 (a)) between the unevenness of the guide surface 48a and the unevenness of the sliding surface 49a so as to mesh with each other. Reciprocating in the direction of R).

As a result, the gap δ formed between the tip end of the movable blade 34 and the hub side wall surface 32a is determined from the maximum value (indicated by the dashed-dotted line in the figure) at the gap formation position as shown in FIG. It changes within the range to the minimum value (shown by a solid line in a figure) in a clearance reduction position.

Fig. 12B shows the change in the gap δ corresponding to the movable range θ of the movable disc 31, and the minimum gap at the clearance reduction position is the unevenness and sliding surface of the guide surface 48a. By optimizing the unevenness of (49a), it can be set to δ ≒ 0 equivalent to almost none. For this reason, since the leakage amount of the airflow through the gap δ is reduced at the gap reducing position, the efficiency of the compressor provided with the variable diffuser can be improved.

In addition, it is preferable that the above-mentioned sliding mechanism 45A is rotated stepwise by the pitch of the unevenness by using the gap reducing position where the unevenness of the guide surface 48a and the unevenness of the sliding surface 49a engage.

That is, since the position of the movable blade 34 is fixed step by step, it is possible to prevent fluctuations in the blade position due to oscillation of the drive device 40A or vibration from the outside, thereby making it possible to stabilize the characteristics of the compressor.

Further, in the above-described variable diffuser, for example, as shown in Fig. 14, the shroud side wall surface 31a between the blades of the movable blade 34 so as to obtain good sliding mobility even in the absence of the gap δ. And the active surface 51 on the hub side wall surface 32a between the blades of the stationary blade 35. Specifically, the active surface may be formed by applying, for example, a fluorine resin such as ethylene tetrafluoride to the wall between the blades of both blades.

In such a configuration, the movable original plate 31 can be smoothly rotated without the gap δ. In addition, when pressure is applied by the diffuser outlet pressure from the back side of the movable original plate 31, even if there are no irregularities such as the guide surface 48a and the sliding surface 49a described above, the gap δ can be eliminated to achieve an improvement in efficiency. Can be.

Incidentally, in the above description, the guide surface 48a and the sliding surface 49a are arc-shaped, but for example, the guide surface 48b having the same sinusoidal irregularities as in the first modification shown in FIG. It is good also as a sliding surface 49b.

Alternatively, as in the second modification shown in Fig. 16, the guide groove 48 'is formed in the housing 11 serving as the fixed side, and the rotatable ring 52 rotatable in place of the guide groove 48' is provided. It is good also as a structure to install as needed. In this case, when the movable disc 31 rotates, the sliding surface 49a of an arc shape or a sinusoidal wave slides with respect to the rotation ring 52, and similarly to guide gaps 48a and 48b mentioned above, The gap δ can be eliminated.

In addition, about the setting of the movable blade and the fixed blade which were demonstrated in said embodiment, you may set the fixed side and the rotating side to reverse. That is, reverse the magnitude of the inlet radius of the fixed blade and the inlet radius of the movable blade, or reverse the magnitude of the blade front edge angle of the fixed blade and the blade front edge angle of the movable blade, The same effect can be obtained even if the blades are reversed or the magnitude of the rear edge radius of the fixed blade and the rear edge radius of the movable blade are reversed.

As described above, according to the variable diffuser structure of the present invention, it is possible to solve the decrease in efficiency caused by the increase in the range and the leakage from the gap δ so as to provide a variable diffuser with improved efficiency. Therefore, compressors, such as a centrifugal compressor and a four-flow compressor provided with this variable diffuser, can improve the performance further.

In addition, this invention is not limited to embodiment mentioned above, It can change suitably in the range which does not deviate from the summary of this invention.

The diffuser and the compressor of the present invention can be applied to, for example, a turbocharger, a marine supercharger, an aeronautical small gas turbine, an industrial centrifugal compressor or a four-flow compressor.

Claims (10)

A diffuser passage is formed between the hub side wall and the shroud side wall to decelerate the airflow discharged from the outer peripheral end of the impeller rotating in the housing, and to restore the static pressure to the static pressure. In Drive means for alternately fixing the diffuser blade in the circumferential direction to the wall member forming the hub side wall surface and the shroud side wall surface, and rotating one of the wall members coaxially with the rotation of the impeller. Variable diffuser. The variable diffuser according to claim 1, wherein the movable range of the wall member rotated by the driving means is set to cover the entire width between adjacent diffuser blades fixed to the wall member on the fixed side. The inlet radius R1 of the diffuser blade provided on the rotation side of the wall member is larger than the inlet radius R2 of the diffuser blade provided on the fixed side of the wall member. > R2) variable diffuser. The blade front edge angle αk2 of the diffuser blade of the diffuser blade of claim 3, wherein the blade front edge angle αk1 of the diffuser blade provided on the rotational side of the wall member is at the same radial position. A variable diffuser, which is set smaller than? The blade front edge angle αk2 of the diffuser blade of the diffuser blade of claim 3, wherein the blade front edge angle αk1 of the diffuser blade provided on the rotational side of the wall member is at the same radial position. A variable diffuser, which is set larger than (αk1> αk2). The variable diffuser according to claim 3, wherein the diffuser blades provided on the fixed side of the wall member are small size ratio blades. The rear edge radius R3 of the diffuser blade provided on the rotational side of the wall member is larger than the rear corner radius R4 of the diffuser blade provided on the fixed side of the wall member (R3> R4). Variable diffuser. The variable diffuser according to any one of claims 3 to 7, wherein the fixed side and the rotating side are set oppositely. The said drive means is a sliding mechanism part in any one of Claims 1-7 with which the rotation side of the said wall surface member reciprocates between a clearance gap formation position and a clearance reduction position with respect to the fixed side of the said wall surface member. A variable diffuser, characterized in that provided. A compressor comprising the variable diffuser according to any one of claims 1 to 9 at an outer circumferential end of an impeller rotating in a housing.

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