JPH08303389A - Centrifugal impeller and its manufacture - Google Patents

Abstract

PURPOSE: To easily produce a high performance centrifugal impeller which is provided with a vane at its inducer part and a side plate. CONSTITUTION: A 3-dimensional blade 1d at an inducer part which changes flow direction from axial to radial direction is formed only in a core plate 1b, and a main vane 1a in external radial direction on its downstream side is formed so that it is fixed to the core plate 1b and a side plate 1c. Also the blade 1d at the inducer part can be produced at a low cost because it is not fixed to the side plate 1c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal impeller used for a centrifugal compressor, a centrifugal blower and the like and a method for manufacturing the centrifugal impeller.

[0002]

2. Description of the Related Art A general centrifugal impeller 1 having side plates used for a centrifugal compressor, a centrifugal blower, etc., has a core plate 1b attached to a rotary shaft 2 and side plates 1 as shown in FIG.
The blades 1a are provided in the form of a circular blade between c and the airflow 8 axially flowing from the inducer portion is pressurized by the blades 1a and blown out in the outer peripheral direction.

As a method for manufacturing a centrifugal impeller having such a side plate, there are a manufacturing method of casting and a manufacturing method of assembling cutting parts by welding or the like. The latter method is, in particular, a method of connecting a blade and a core plate or a side plate: 1) A blade is formed on one plate (for example, a core plate) by machining and the other plate (for example, Side plate) Welding method 2) Manufacture the blade independently and weld both plates (core plate and side plate) to both ends of it 3) If the height of the blade is low and normal welding is difficult, Method of forming blades by machining on the plate of No. 4 and slot welding the tip of this blade to the other plate 4) Forming blades on each of both plates by machining and forming blades and blades There are methods such as diffusion bonding. In addition, as described in Japanese Utility Model Laid-Open No. 62-40298, a plurality of ribs are provided upstream of the blades of the centrifugal impeller, and side plates with ribs and core plates with blades are integrated via main blades. There is also a way to assemble it.

When the centrifugal impeller is classified by the blade shape, it can be divided into a two-dimensional impeller and a three-dimensional impeller. Generally, the three-dimensional impeller has higher performance than the two-dimensional impeller, but has a problem of high manufacturing cost. In particular, when the twist of the blade, that is, the three-dimensionality of the blade becomes remarkable, it takes a lot of time to weld and join the above-mentioned methods 1) and 2). Especially, the blade of the inducer section has a flow path in addition to the bending of the blade. Also, the welding work becomes difficult because the axial direction changes from the radial direction. Further, there is a problem that it becomes difficult to finish the surface after welding. Further, if the height of the blades is further reduced, there is a problem that the manufacturing is difficult even by the methods 3) and 4), not only the manufacturing cost becomes high, but also the reliability in strength is lowered.

Regarding the arrangement of the blades in the centrifugal impeller, as described in Japanese Patent Application Laid-Open No. 62-291498, the blades are divided into a plurality of pieces in the gas flow direction, and the divided blades have a circumferential phase. There is a gap of
As described in Japanese Utility Model Publication No. 3-55839, the blade is divided into two in the air flow direction, and the number of blades on the downstream side is doubled on the upstream side. The blades described in these publications are all applied to centrifugal impellers without side plates.

Looking at the shape of the centrifugal impeller alone, with respect to the thickness of the blade in addition to the two-dimensional or three-dimensional shape, the thickness of the blade is in the range from the leading edge to the trailing edge of the blade. In addition to a fixed impeller with a constant value, U.S. Pat.
No. 8,865 specification and drawings and JP-A-3-21099
As described in Japanese Unexamined Patent Publication (Kokai), there is one in which the thickness of the blade is gradually increased from the leading edge to the trailing edge. These centrifugal impellers are applied to impellers having a small handling flow rate, that is, a small capacity, in other words, a small specific speed. Therefore, the height of the impeller is low and the impeller has a two-dimensional shape.

[0007]

In a three-dimensional blade, if the blade angle can be adjusted to the airflow over the entire area of the flow path at the inlet of the blade in the height direction, high efficiency can be obtained. However, a three-dimensional centrifugal impeller has a high manufacturing cost, and a compressor with a small handling flow rate, that is, a low specific speed centrifugal impeller has a low flow passage height, and thus has a side plate. Is extremely difficult to manufacture. Therefore, in a multi-stage compressor, a two-dimensional centrifugal impeller is used, especially in a low specific speed stage. Further, conventionally, in the low specific velocity region, the height of the flow path, that is, the height of the blade is low, so that it is considered that the effect of making the blade three-dimensional is small.

In the conventional two-dimensional centrifugal impeller, the leading edge of the impeller is located at the portion where the airflow flowing into the centrifugal impeller is diverted from the axial direction to the radial direction because the shape of the impeller is two-dimensional. Therefore, the average radius of the leading edge of the two-dimensional centrifugal impeller is larger than that of the centrifugal impeller having the inducer portion of the three-dimensional blade. Therefore, at the same rotational speed, the peripheral speed of the centrifugal impeller at the inflow portion is increased, and the inflow relative speed is also increased.

The centrifugal impeller described in Japanese Utility Model Laid-Open No. 62-40298 has a plurality of ribs provided upstream of the blades of the centrifugal impeller, that is, in the portion where the air flow is directed in the axial direction.
Even if this rib is regarded as a kind of blade, it has a merit in terms of performance because it is also connected to the side plate side and has a plate shape attached only to the axial direction part. On the contrary, there is a high possibility that the airflow upstream of the impeller is disturbed and the performance is deteriorated.

Therefore, a first object of the present invention is to provide a centrifugal impeller in which friction loss is reduced by reducing the relative velocity of the airflow flowing into the inducer portion of the centrifugal impeller and which is easy to manufacture. It is in.

The air flow inside the centrifugal impeller becomes a deceleration flow as a whole, and high efficiency can be obtained by performing appropriate deceleration. In order to stably operate the fluid machine over a wide operating range, the centrifugal impeller must prevent air flow separation and stall inside. One of the methods for preventing the peeling and the stall is disclosed in JP-A-62-291.
As in the centrifugal impeller described in Japanese Patent Publication No. 498 and Japanese Utility Model Publication No. 3-55839, by arranging the blades in two rows and shifting the arrangement of the blades in the first row and the second row in the circumferential direction, 1 There is a method of suppressing the development of the boundary layer on the blade surface by the blowing effect of the blades in the row. However, since all of these methods are performed by a centrifugal impeller having no side plate, a leaked air flow is generated on the side plate side of the tip of the blade. This method is also effective in the case of a centrifugal impeller, which has a large specific speed and the effect of this leakage is extremely small with respect to the entire flow, but in the low specific speed stage, the ratio of the tip clearance to the blade height is small. The effect of the boundary layer is different between the tip side and the root side of the blade because the flow rate increases and the ratio of the leaked air flow increases. Also, in the low specific speed stage, the loss due to the leakage flow itself becomes large,
The use of centrifugal impellers without side plates is not preferable per se.

Therefore, a second object of the present invention is to provide a centrifugal impeller having a wide working range by effectively suppressing the boundary layer in a centrifugal impeller with a side plate which is easy to manufacture.

On the other hand, it is not so important for the centrifugal impeller to have a wide working range, and it is sometimes desired that the centrifugal impeller can be manufactured with high efficiency and at the lowest possible cost.

Therefore, a third object of the present invention is to provide a centrifugal impeller with high efficiency and low manufacturing cost.

In order to reduce the friction loss in the centrifugal impeller, US Pat. No. 3,788,865 specification and drawings and Japanese Patent Laid-Open No. 3-21 have been proposed for an impeller having a relatively small specific speed.
As described in Japanese Patent Laid-Open No. 0099, there is a method of increasing the height of the blade by increasing the thickness of the blade. Although this method is an effective method for reducing the friction loss by reducing the wetted area of the flow path, it is not always sufficient.

Therefore, a fourth object of the present invention is to provide a highly efficient centrifugal impeller with further reduced friction loss by reducing the average flow velocity in the flow path of the centrifugal impeller.

In the air flow inside the centrifugal impeller, the place where the relative flow velocity is the largest is near the inlet, and in the impeller having the vane in the inducer portion, the friction loss increases as the flow velocity in that portion increases. Therefore, it is important to finish the surface of the blade in this portion, but it is difficult to finish the work with the conventional centrifugal impeller.

Therefore, a fifth object of the present invention is to provide a method of manufacturing a centrifugal impeller in which the surface finishing of the blade of the inducer portion is easy.

[0019]

The feature of the present invention that achieves the above first object is that the flow is changed from the axial direction to the radial direction, that is, the vanes of the inducer portion are either core plates or side plates. It is formed so that it is connected to only one side, and the core plate and the side plate are connected via the downstream main outward blade in the radial direction to reduce the average radius of the leading edge of the blade at the inlet of the centrifugal impeller. .

Another feature of the present invention that achieves the second object is that the vanes of the inducer portion are formed on either the core plate or the side plates, and the core plate and the side plates are radially outwardly directed downstream thereof. The main blades of the inducer section are separated from each other, and the trailing edge of the outlet blade of the inducer section and the leading edge of the main blade are shifted in the circumferential direction. is there.

The feature of the present invention that achieves the third object is that the blade formed on either the core plate or the side plate of the inducer section and the main blade attached to the core plate and the side plate downstream thereof. It is formed integrally.

The feature of the present invention that achieves the above-mentioned fourth object is that the blades of the centrifugal impeller near the inlet, that is, the blades of the inducer portion are formed on either the core plate or the side plate, and the core plate and the side plate are the same. The blades are coupled via a downstream radial outward main blade, and the blade thickness of at least one of the blade of the inducer portion and the main blade is gradually increased from the front edge to the rear edge thereof, and the predetermined thickness is obtained. That is, the wetted area of the flow channel is reduced while ensuring the flow channel area.

The feature of the present invention that achieves the fifth object is that the blade of the inducer portion of the centrifugal impeller is formed on either the core plate or the side plate, and the core plate and the side plate are provided via the main blade. It is to combine and manufacture.

[0024]

The blade of the inducer portion, which is difficult to process and requires a lot of work, is formed on only one of the core plate and the side plate. Therefore, compared with the conventional three-dimensional impeller, which is connected on both sides. It can be easily processed. Since the core plate and the side plate are connected via the main blade, even an impeller having a small specific speed can be easily formed by a conventional processing method.

Since the airflow in the centrifugal impeller can reduce the average radius of the leading edge of the blade by the blade of the inducer portion, the circumferential velocity at the inlet of the blade is smaller than that of the centrifugal impeller having the same rotational speed. It becomes smaller and the inflow relative velocity becomes smaller than that when the radius is large. If the relative velocity at the inlet is reduced and the relative velocity ratio at the inlet and outlet of the centrifugal impeller, that is, the deceleration rate of the relative velocity is designed to be about the same, the relative velocity at the outlet can also be reduced, so that the average relative velocity in the impeller is reduced. Further, in the three-dimensional blade of the inducer portion, the incident angle becomes small by adjusting the angle of the blade to the inflow angle of the air flow over the entire leading edge of the blade at the inlet, so that the flow can flow into the smooth. .

Although there is a gap between the tip of the blade of the inducer section and the facing surface of the core plate or side plate, there is no relative movement between the side plate or core plate and the blade, so this gap is present. Can be made extremely small, and
Even if the tips of the blades of the blade portion come into contact with the core plate or the side plate, there is no inconvenience, so that the machining is easy. .

In such a centrifugal impeller with side plates, the blade of the inducer section and the main blade are separated, and the trailing edge of the blade at the outlet of the inducer section and the leading edge of the main blade are displaced in the circumferential direction. As a result, the airflow flowing out from the pressure surface side of the inducer portion flows into the suction surface side of the main blade, and the blowing effect prevents the development of the boundary layer on the suction surface of the main blade and the accompanying separation. .

In an impeller with a side plate having a relatively large specific speed, if it is desired to make the centrifugal impeller as inexpensive as possible without requiring a wide operating range, the blade of the inducer portion and the main blade are integrally formed. By doing so, the processing cost is reduced. In particular, if the blade is processed independently and joined to the core plate or side plate by welding etc., machining work by machining is not required, and welding work of the most difficult part is also omitted in joining by welding. Therefore, the manufacturing cost is reduced.

The reduction of the friction loss of the fluid depends on the wetted area,
That is, it can be obtained by reducing the area in which the fluid is in contact with the flow path and reducing the flow velocity. The vanes provided in the inducer section reduce the average radius of the leading edge to reduce the inflow relative velocity, and gradually increase the thickness of the vane from its leading edge to its trailing edge while increasing the flow passage height. Due to the synergistic effect of increasing the height and shortening the length of the flow path cross section, the friction loss is significantly reduced even when the length of the flow path of the inducer portion is taken into consideration.

For example, when the blade is welded to only one of the core plate and the side plate, the surface finish including the fillet of the welded portion can be easily achieved in that state.
In addition, a smooth surface can be processed when machining is performed. In any case, it is easy to process the surface of the flow path of the inducer section smoothly. As a result, the friction loss of the inducer portion having the highest flow velocity in the centrifugal impeller is reduced. Further, even in the centrifugal impeller having a relatively low specific speed, the three-dimensional impeller can be easily provided in the inducer portion.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention and shows a partial cross section of one stage of a multi-stage compressor. This multi-stage compressor is composed of a centrifugal impeller 1, a rotary shaft 2, a diffuser 3, a return flow passage 4, an impeller labyrinth 5, a stage labyrinth 6, and the like, and air flows in through a suction flow passage 7. , The impeller 1, the diffuser 3, and the return flow path 4 to be sent to the next stage.

The centrifugal impeller 1 of this embodiment is a centrifugal impeller having a relatively low impeller height, that is, a low specific speed, and the impeller 1d has a three-dimensional shape and is welded. Alternatively, it is formed on the core plate 1b by carving. The blade 1d can be formed by welding or shaving and finishing in a state where the periphery of the blade 1d is open, so that even a three-dimensional shape can be formed relatively easily.

On the other hand, the main blade 1a is formed on the side plate 1c (or the core plate 1b) by welding or shaving, and after the necessary finishing work etc., the tip of the main blade 1a is attached to the other core plate 1b (or the side plate). 1c) by welding and joining to the facing surface, the main blade 1a, the core plate 1b, the side plate 1c, the blade 1
The centrifugal impeller 1 in which d is integrated is completed.

The side plate 1c and the core plate 1b described above can be easily joined by the work of welding the tips of the main blades 1a similar to the conventional two-dimensional centrifugal impeller, and the core plate 1c can be easily connected. When connecting 1b and side plate 1c, 3 of the inducer part is used.
Since it is not necessary to weld the tip of the dimension blade 1d, it is possible to easily manufacture a high-performance centrifugal impeller having a low specific speed and a three-dimensional blade in the inducer portion.

In this embodiment, since the centrifugal impeller having a low specific speed is assumed as described above, the blade 1d of the inducer portion is made three-dimensional so that the leading edge of the blade is provided at the inlet of the blade. Even if the angle of the blade is matched to the inflow angle of the flow in the whole area, the effect of significantly reducing the inflow loss cannot be expected. However, since the inflow relative speed can be reduced by providing the inducer portion, this point will be described below with reference to FIGS. 2 and 3.

FIG. 2 shows a velocity triangle at the inlet of the centrifugal impeller 1. The solid line is the velocity triangle at the front edge of the blade 1d of the inducer portion of this embodiment, and the broken line is the velocity triangle at the inlet of the conventional two-dimensional centrifugal impeller shown in FIG.

Assuming that the velocity flowing from the upstream side of the centrifugal impeller in the axial direction (radial direction in the case of a conventional two-dimensional centrifugal impeller) is C ₁ and both are the same, the peripheral speed of the leading edge of the vane is: When the number of rotations is the same, u ₁ <u ₁ 'due to the difference in average radius r.
It becomes a relationship. Therefore, the inflow relative velocity w ₁ of this embodiment
2 becomes smaller than the relative flow velocity w ₁ 'of the conventional centrifugal impeller as is apparent from FIG.

FIG. 3 shows the relative velocity distribution in the centrifugal impeller, where the vertical axis is the relative velocity and the horizontal axis is the flow path length. When the inflow relative velocity w ₁ is reduced as in this embodiment as compared with the broken line showing the characteristics of the conventional centrifugal impeller, when the outlets are the same, the relative velocity distribution as shown by the one-dot chain line, The average relative velocity in the centrifugal impeller becomes smaller.
Further, if the deceleration rate ((w ₁ −w ₂ ) / w ₁ ) in the centrifugal impeller is designed to be the same, the relative speed w at the exit of the centrifugal impeller
_{Since 2} becomes smaller, the relative velocity distribution becomes as shown by the solid line, and the average relative velocity in the centrifugal impeller can be further reduced.

From the above, in this embodiment, although the length of the blade is increased by the amount of the inducer portion, the average relative speed in the centrifugal impeller is significantly reduced, so that the friction loss is reduced and the efficiency is improved. Can be improved.

FIG. 4 shows an example of the inducer in the embodiment of FIG.
The cross-sectional shape of the flow path in the vicinity of the slot of the saw portion is shown in FIG.
Is a flow passage cross section of the inducer section, assuming that the blade 1a ′ of the inducer section is formed by extending the main blade 1a and the tip thereof is welded to the core plate or side plate on the other side. The shape. Since the joining by welding is restricted in terms of welding technology, the thickness t'of the blade 1a 'becomes thicker, and the surface finishing is often difficult. On the other hand, the blade 1d of the inducer portion in this embodiment is simply formed integrally with the core plate 1b by shaving, and is not joined (welded) to the side plate 1c, so that its surface is machined sufficiently smoothly. Further, the thickness t of the blade 1d can be reduced by considering only the fluid force. Therefore,
In this embodiment, not only the friction loss in the inducer portion can be reduced, but also the flow passage cross-sectional area can be made large, as is clear by comparing FIGS. 4 and 5. Of course, there are cases where it is not necessary to make the cross-sectional area larger than a predetermined value, but in any case, there is an advantage that the range of design choices becomes wider and the design becomes easier. These effects can be obtained not only in this embodiment but also in the case of a centrifugal impeller having a large specific speed. Although there is a gap λ between the tip of the blade 1d of the inducer portion and the side plate 1c, the tip of the blade 1d of the inducer portion is in contact with the facing surface of the side plate 1c. Since it is easy to form, the influence of leakage from the gap is negligible.

As described above, this embodiment can provide a centrifugal impeller having a small friction loss, which can be easily designed and manufactured even in a low specific speed stage.

FIG. 6 shows a second embodiment of the present invention. In this embodiment, the blade 1d of the inducer portion and the main blade 1a are formed separately, but the effect of reducing the friction loss due to the reduction of the relative inflow velocity due to the blade 1d of the inducer portion is as described above. This is similar to the case of the first embodiment. In addition to this embodiment, the vane 1 of the inducer section is added.
d and the main blade 1a are separated, the blade 1d of the inducer portion is formed on the core plate 1b, and the main blade 1a is formed on the side plate 1c. The optimum processing machine for each processing mode is selected. It is possible to shorten the processing time by enabling it to be used simultaneously and processing simultaneously in parallel.

FIG. 7 shows a third embodiment of the present invention in which the trailing edge of the blade 1d of the inducer portion and the leading edge of the main blade 1a are circumferentially offset. When the blades a and 1d are arranged in this manner, the airflow 8a flowing out from the trailing edge of the blade 1d of the inducer portion flows into the negative pressure surface side of the main blade 1a. By doing so, it is possible to supply a fluid having a large momentum to the suction surface side of the main blade 1a where the fluid having the lowest momentum tends to gather and the boundary layer tends to become thick, and the development of the boundary layer and separation of the flow in this portion can be performed. Can be suppressed. Therefore, as the centrifugal impeller 1, it is difficult for the centrifugal impeller 1 to stall even when it is operated in a low flow rate region, and it is possible to provide a compressor having a wide operating range.

FIG. 8 shows a fourth embodiment of the present invention. In contrast to the conventional two-dimensional impeller of the same specifications shown in FIG. 20 and the third embodiment of the present invention, an indu -The blade height of the blades 1e and the main blades 1f of the support portion is high, and the main blades 1f are
The thickness of is gradually increasing toward the downstream. 9 and 10 show the CC cross section of the centrifugal impeller shown in FIG. 8 and the BB cross section of the conventional centrifugal impeller shown in FIG. 20 corresponding thereto. The height b of the impeller 1f of the centrifugal impeller according to the present invention shown in FIG. 9 is higher than the height b ′ of the impeller 1a of the conventional centrifugal impeller shown in FIG. Although the cross-sectional areas are substantially the same, the contact length between the fluid and the wall is shorter in the centrifugal impeller of this embodiment shown in FIG. 9, so that the wetted area is smaller and therefore the friction loss is smaller. This effect is achieved, for example, in US Pat. No. 3,788,8.
This is the same as the centrifugal impeller described in the specification and drawings of JP-A No. 65-21 and Japanese Patent Application Laid-Open No. 3-21099, but in this embodiment, since the inducer portion is provided upstream of the flow,
Compared with the conventional two-dimensional centrifugal impeller, the inflow relative velocity and average relative velocity are small. Therefore, the friction loss is reduced due to the synergistic effect of the reduction in speed and the reduction in the wetted area, and high efficiency can be obtained. Naturally, this effect is greater in a centrifugal impeller having a low specific speed with a large friction loss ratio.

FIG. 11 shows a fifth embodiment of the present invention. In this embodiment, in relation to the second embodiment of the present invention described above, the blade 1g of the inducer portion is formed to have a three-dimensional shape and the main blade 1h is formed to have a two-dimensional shape. Of these, the main blade 1h having a two-dimensional shape is easier to manufacture than the three-dimensional blade 1g and is advantageous in terms of manufacturing cost.

FIG. 12 shows a sixth embodiment of the present invention, in which a blade i having a shape in which the main blade and the blade of the inducer portion are integrated is manufactured, and the side plate side of the inducer portion is formed. The removed region is connected to the core plate 1b and the side plate 1c by welding or the like. Since such an integral blade 1i can be formed by pressing or the like, it is possible to reduce the manufacturing cost as compared with the formation by shaving.

FIG. 13 shows a seventh embodiment of the present invention. This embodiment relates to the fifth embodiment, and the blade 1j in which the main blade and the blade of the inducer portion are integrally formed is
The height of the blades of the inducer portion and the main blade portion is high, and the thickness of the blade 1j gradually increases toward the downstream side. This centrifugal impeller can also be manufactured at low cost and have a small friction loss.

14 to 19 show still another embodiment of the present invention, which is particularly characterized by the manufacturing method.

The eighth embodiment shown in FIG. 14 is an inducer.
The blade 1d of the blade portion is on the side of the core plate 1b, and the main blade 1a is on the side plate 1c
Each side is machined by machining, and thereafter, the tips of the main blades 1a and the facing surface of the core plate 1b are welded to join the two to complete the centrifugal impeller. Of course, conversely, the blade 1d of the inducer portion may be formed on the side plate 1c side and the main blade 1a may be formed on the core plate 1c side by machining, and then the two may be welded and joined together. It is possible.

According to this manufacturing method, most of the surfaces of the blades 1a and 1d are machined, and since the blade 1d of the inducer portion having the highest flow velocity has no welding portion, the machining accuracy is high and the surface is smooth. Friction loss is greatly reduced because it can be processed into.

The ninth embodiment shown in FIG.
Main blades 1k and 1r obtained by dividing the blade 1d of the support portion on the side of the core plate 1b into two in the height direction are machined by machining on both the side of the core plate 1b and the side plate 1c.
This is a method for manufacturing a centrifugal impeller in which tips of 1r are diffusion-bonded to each other. This manufacturing method is effective when the blade height is low in the low specific speed stage of the multi-stage compressor and it is difficult to apply a normal welding operation. Since the blade 1d of the inducer portion has no welded portion as in the above-described embodiment, it can be easily processed even in a centrifugal impeller having a relatively low specific speed, the processing accuracy is high, and the surface can be processed smoothly. Therefore, friction loss can also be reduced.

In the tenth embodiment shown in FIG. 16, the blade 1d of the inducer portion is on the core plate 1b side, and the main blade 1a is the side plate 1.
This is a manufacturing method in which the centrifugal impeller is completed by welding and attaching to the c side, performing surface finishing, etc., and then joining the tip of the main blade 1a and the facing surface of the core plate 1b by welding. Of course, conversely, the blade 1d of the inducer portion may be welded to the side plate 1c side and the main blade 1a may be welded to the core plate 1b side, and then the both may be joined together.

This manufacturing method is effective when the relative speed is relatively high and the welding operation is easy, and has an advantage that the manufacturing cost is lower than that in the case where the blades 1a and 1d are formed by machining. is there. Further, the vane 1d of the inducer portion can be subjected to surface finishing processing while being welded to one side (core plate 1b or side plate 1c). It is extremely easy as compared with the case of doing.

FIG. 17 shows an eleventh embodiment of the present invention. The side plate is divided into two side plate portions 1m and 1n,
The blade 1d of the inducer portion is formed on the upstream side plate 1m by welding or machining, and the main blade 1a is formed on the downstream side plate 1n by welding or machining. 1a tip and mandrel 1b
The opposing surfaces of are joined by welding. Then, surface finishing is performed on the blades 1d and the main blades 1a of the inducer portion as necessary, and finally, the side plate 1m on the upstream side and the side plate 1n on the downstream side.
Are joined by welding or the like. This manufacturing method uses two core plates.
The same operation can be carried out by dividing into two parts and providing the vane 1d of the inducer portion on the upstream core plate.

According to this manufacturing method, since the impeller can be assembled without applying processing (welding) to the surfaces of the blades 1a and 1d whose surfaces have been finished, the surface is smooth and the friction loss is small. A centrifugal impeller can be provided. Further, the blade 1d of the inducer portion is the blade 1d.
Since the split surfaces can be joined by welding while the tip side of d is brought into contact with the mating plate, the blade 1d
The gap at the tip of the can be made extremely small.

FIG. 18 shows a twelfth embodiment of the present invention. The side plate is divided into two parts, the side plate 1 on the upstream side.
A blade 1d of the inducer portion is formed on m by welding or machining, and the side plate 1n on the downstream side, the core plate 1b, and the main blade 1a are integrally formed by casting. Then, the blades 1d and the main blades 1a of the inducer section are surface-finished as required, and finally, the side plate 1 on the upstream side.
m and the side plate 1n on the downstream side are joined by welding or the like. This manufacturing method can be similarly carried out even if the core plate 1b side is divided into two and the blades 1d of the inducer portion are provided on the upstream core plate.

In this manufacturing method, an inductor having a complicated shape is used.
Since the blades 1d of the saw portion are processed separately and the casting portion has a simple shape, casting is easy, and it is advantageous to reduce the manufacturing cost by mass production. Therefore, according to this manufacturing method, the main blade portion on the downstream side is prepared as a common component for the centrifugal impeller in a certain range of specifications, and the inducer is provided for the difference in the air flow due to the difference in the specifications within the range. If the centrifugal impeller is manufactured by changing the shape of the blades 1d of the support portion and correspondingly, the manufacturing cost can be significantly reduced.

FIG. 19 shows a thirteenth embodiment of the present invention. In this embodiment, the blade of the inducer portion and the main blade are integrally formed as a blade 1p, and only the tip of the main blade portion of the blade 1p is joined to the side plate 1c by welding or the like. In this manufacturing method, surface finishing is performed as necessary, and finally the facing surfaces of the tips of the core plate 1b and the blades 1p are joined by welding or the like.

This manufacturing method is suitable for a centrifugal impeller having a relatively high specific speed, that is, when the height of the blade is high and the welding work is easy, and if the integral processing of the blade 1p is performed by a press or the like, it is machined. Since the shaving work due to is eliminated, the manufacturing becomes easier and the manufacturing cost is reduced.

[0060]

INDUSTRIAL APPLICABILITY The present invention provides a centrifugal impeller having a three-dimensional impeller between a side plate and a core plate, by providing the impeller in the inducer portion so as to be coupled to only one of the side plate and the core plate. Can be manufactured at low cost, and in particular, manufacturing of an impeller with a low specific speed can be facilitated.

Moreover, it is possible to provide a centrifugal impeller having a high efficiency and a wide operating range, by significantly reducing the friction loss in the inducer portion.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional side view of a multi-stage compressor illustrating a first embodiment of the present invention.

FIG. 2 is a velocity triangle characteristic diagram of inlets of a centrifugal impeller according to the present invention and a conventional impeller.

FIG. 3 is a relative velocity distribution characteristic diagram of a centrifugal impeller according to the present invention and a conventional centrifugal impeller.

4 is a cross-sectional view of the inducer section AA of the centrifugal impeller according to the present invention shown in FIG.

FIG. 5 is a cross-sectional view of a conventional centrifugal impeller when the main blade is extended to the inducer section.

FIG. 6 shows a second embodiment of the present invention and is a vertical cross-sectional front view showing the blade shape of the centrifugal impeller.

FIG. 7 shows a third embodiment of the present invention and is a vertical sectional front view showing the blade shape of the centrifugal impeller.

FIG. 8 shows a fourth embodiment of the present invention and is a vertical sectional side view of a main part of a multistage compressor and a vertical sectional front view showing a blade shape of a centrifugal impeller.

9 is a sectional view taken along line CC of the flow path shape of the centrifugal impeller according to the present invention shown in FIG.

10 is a BB cross-sectional view showing the flow path shape of the conventional centrifugal impeller shown in FIG.

FIG. 11 shows a fifth embodiment of the present invention and is a vertical cross-sectional front view showing the blade shape of the centrifugal impeller.

FIG. 12 shows a sixth embodiment of the present invention and is a vertical sectional side view of a centrifugal impeller and a vertical sectional front view showing a blade shape.

FIG. 13 shows a seventh embodiment of the present invention and is a vertical sectional side view of a centrifugal impeller and a vertical sectional front view showing a blade shape.

FIG. 14 shows an eighth embodiment of the present invention and is a vertical sectional side view showing a manufacturing process of a centrifugal impeller.

FIG. 15 shows a ninth embodiment of the present invention and is a vertical sectional side view showing a manufacturing process of a centrifugal impeller.

FIG. 16 shows a tenth embodiment of the present invention and is a vertical cross-sectional side view showing a manufacturing process of a centrifugal impeller.

FIG. 17 shows an eleventh embodiment of the present invention and is a vertical cross-sectional side view showing a manufacturing process of a centrifugal impeller.

FIG. 18 shows a twelfth embodiment of the present invention and is a vertical sectional side view showing a manufacturing process of a centrifugal impeller.

FIG. 19 shows a thirteenth embodiment of the present invention and is a vertical sectional side view showing a manufacturing process of a centrifugal impeller.

FIG. 20 is a vertical sectional side view and a vertical sectional front view showing a blade shape of a centrifugal impeller provided with a conventional two-dimensional blade.

[Explanation of symbols]

1 ... Root car, 1a, 1f, 1h ... Main blade, 1b ... Mandrel, 1
c ... side plate, 1d, 1e, 1g ... blades of the inducer portion,
1i, 1j ... blades, 2 ... rotation axis, 3 ... diffuser, 4
... Return flow path, 5,6 ... Labyrinth, 7 ... Suction flow path, 8 ...
air flow.

Claims (13)

[Claims] 1. A centrifugal impeller provided with blades arranged in a circular cascade between a core plate and a side plate, wherein the blades of an inducer section for changing the flow from an axial direction to a radial direction are the core plate or the side plate. A centrifugal impeller characterized in that it is provided so as to be connected to only one of them, and a main blade downstream of the inducer portion is provided so as to be connected to both a core plate and a side plate. 2. The centrifugal impeller according to claim 1, wherein the blade of the inducer portion and the main blade downstream thereof are formed separately. 3. The blade according to claim 2, wherein the rear end edge portion of the blade of the inducer portion is provided so as to be displaced from the front end edge portion of the main blade so as to be located on the suction surface side of the main blade. Centrifugal impeller. 4. The centrifuge according to claim 2, wherein at least one of the blade and the main blade of the inducer portion is thicker at a middle portion and a rear end edge portion in a flow direction than at a front end edge portion. Impeller. 5. The centrifugal impeller according to claim 1, wherein the blade of the inducer portion is formed in a three-dimensional shape and the main blade is formed in a two-dimensional shape. 6. The centrifugal impeller according to claim 1, wherein the blade of the inducer portion and the main blade are integrally formed. 7. The centrifugal impeller according to claim 6, wherein the blades of the inducer portion have a blade thickness that is greater in the middle portion and the rear end edge portion in the flow direction than in the front end edge portion. 8. An inducer portion, which is composed of blades arranged in a circular blade arrangement between a core plate and a side plate, and which changes a flow from an axial direction to a radial direction, and a plurality of radial outward radial portions downstream thereof. In the method for manufacturing a centrifugal impeller having blades, the forming of the blades of the inducer portion on either the core plate or the side plate, and then connecting the core plate and the side plate via the downstream main blade. A method for manufacturing a centrifugal impeller, characterized by: 9. The method according to claim 8, wherein one of the core plate and the side plate is separated into an inducer portion and a radiating portion on an outer periphery thereof, and a blade of the inducer portion is formed in the inducer portion.
A method for manufacturing a centrifugal impeller, comprising forming the radiating portion in a state of being coupled to a plate on the other side via a main blade, and then coupling the inducer portion inside the radiating portion. 10. The method for manufacturing a centrifugal impeller according to claim 8 or 9, wherein the joining is performed by diffusion joining. 11. The method for manufacturing a centrifugal impeller according to claim 9, wherein the radiating portion of the separated core plate or side plate, the main blade and the plate on the other side are integrally cast. 12. An inducer portion, which is composed of vanes arranged in a circular blade arrangement between a core plate and a side plate, and which changes a flow from an axial direction to a radial direction, and a plurality of radially outwardly directed portions downstream thereof. In a method for manufacturing a centrifugal impeller having blades, the blade of the inducer portion and a portion of the downstream portion thereof facing outward in the radial direction is integrally formed, and the blade of the inducer portion has a core plate side or a side plate side. A method for manufacturing a centrifugal impeller, characterized in that the blade is connected to a core plate and a side plate except one of the sides. 13. The method for manufacturing a centrifugal impeller according to claim 12, wherein the bonding is performed by diffusion bonding.