JPH0663897U - Centrifugal compressor with vaneless diffuser - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to optimally adjust the flow passage cross-sectional area of the diffuser according to the discharge flow rate. [Structure] In a centrifugal compressor 11 having a vaneless diffuser 16 on the outlet side of an impeller 14, the diffuser 16 is provided with a throttle portion 21 for varying a flow passage cross-sectional area B in accordance with a discharge flow rate. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a centrifugal compressor with a vaneless diffuser, and more particularly to a centrifugal compressor with a vaneless diffuser that can change the flow passage cross-sectional area of the diffuser according to the discharge flow rate.

[0002]

[Prior art]

 Generally, there is known a centrifugal compressor that employs a vaneless diffuser as shown in FIG. 2 in order to convert the dynamic pressure of the compressed air introduced from the compression section to the discharge section into static pressure.

As shown in the figure, the centrifugal compressor 1 has an impeller 4 for introducing and compressing air from a suction part 3 in a casing 2, and an outlet side of the impeller 4 and a spiral-shaped discharge part. A diffuser 6 without blades is provided between the two.

[0004]

[Problems to be solved by the device]

 By the way, since the flow passage cross-sectional area A of the diffuser 6 is always constant, the discharge pressure becomes high in the low flow rate region, and surging easily occurs. In addition, as shown in FIG. 3, turning stall occurs, causing backflow and a separation phenomenon, which causes vibration noise. If the cross-sectional area A of the flow path of the diffuser 6 is narrowed in advance to prevent these, there is a problem that the flow resistance is reduced in the large flow rate region, and the flow rate reduction efficiency is reduced.

The present invention was devised to effectively solve the above problems.

An object of the present invention is to provide a centrifugal compressor with a vaneless diffuser that can optimally adjust the flow passage cross-sectional area of the diffuser according to the discharge flow rate.

[0007]

Means for Solving the Problems The present invention relates to a centrifugal compressor having a vaneless diffuser on the outlet side of an impeller, in which the diffuser is provided with a throttle section for varying the flow passage cross-sectional area according to the discharge flow rate. is there.

[0008]

[Action]

 In this way, the flow passage cross-sectional area of the diffuser is changed by the throttle portion, so that the optimum flow passage cross-sectional area can be obtained according to the discharge flow rate. That is, in the small flow rate region, the flow passage cross-sectional area is reduced to smooth the flow, and in the large flow amount region, the flow passage cross-sectional area is increased to reduce the flow resistance.

[0009]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, in a casing 12 of a centrifugal compressor 11, an impeller 14 for introducing and compressing air from a suction part 13 is provided, and an outlet side of the impeller 14 and a spiral shape are provided. A vaneless diffuser 16 is provided between the discharge unit 15 and the discharge unit 15.

In particular, the vaneless diffuser 16 is provided with a throttle portion 21 that can change the flow passage cross-sectional area of the diffuser 16, and the throttle portion 21 forms one side portion of the diffuser 16 and is a disc-shaped diffuser side plate. It is composed of 22. The diffuser side plate 22 is provided in a recess 23 formed in the diffuser 16 so as to be reciprocally movable toward the flow passage cross section B side.

That is, one end of, for example, three rods 24 arranged at equal intervals in the circumferential direction are connected to the diffuser side plate 22, and the other end portions of these rods 24 are reciprocally movable in the cylinder 25. It is connected to a piston 26 provided. The head chamber 27 defined by the piston 26 in the cylinder 25 is connected to the discharge portion 15 via a communication passage 28, while the rod chamber 29 defined in the cylinder 25 defines a communication passage 31 in the suction portion 13. Connected through. A spring 32 for urging the diffuser side plate 22 in the direction of enlarging the flow passage cross-sectional area B 1 is accommodated in the rod chamber 29.

Therefore, when operating in the small flow rate region, the pressure difference between the suction portion 13 and the discharge portion 15 is large, so that the capacity of the header chamber 27 is increased by overcoming the force of the spring 32, and the diffuser side plate 22 is The flow passage cross-sectional area B of the diffuser 16 is narrowed. For this reason, the flow becomes smooth, and it becomes difficult for turning to stall or surging. Therefore, when operating in a large flow rate range, the pressure difference between the suction part 13 and the discharge part 15 decreases conversely, so the force of the spring 32 acts and the volume of the rod chamber 29 expands, and the diffuser side plate 22 passes through the flow path. The cross-sectional area B will be enlarged. When the flow passage cross-sectional area B increases at a large flow rate, the resistance decreases and the flow passage reduction efficiency can be increased.

Therefore, the discharge flow rate from the low flow rate region to the high flow rate region is detected by the pressure difference between the suction section 13 and the discharge section 15, and the flow passage cross-sectional area of the diffuser 16 is automatically and optimally adjusted according to the change in the pressure difference. It can be changed and a smooth flow can be obtained.

[0015]

[Effect of device]

 In summary, according to the present invention, since the flow passage cross-sectional area of the diffuser is changed according to the discharge flow rate, it is possible to prevent swirling stall and surging in a small flow rate range and prevent a decrease in flow rate reduction efficiency in a large flow rate range.

[Brief description of drawings]

FIG. 1 is a sectional view showing a centrifugal compressor with a vaneless diffuser according to the present invention.

FIG. 2 is a cross-sectional view showing a conventional centrifugal compressor with a vaneless diffuser.

FIG. 3 is a diagram showing a peeling phenomenon.

[Explanation of symbols]

 14 Impeller 16 Bladeless diffuser 21 Throttle

Claims (1)

[Scope of utility model registration request] 1. A centrifugal compressor having a vaneless diffuser on the outlet side of an impeller, wherein the diffuser is provided with a throttle section for varying a flow passage cross-sectional area according to a discharge flow rate. Centrifugal compressor.