JPH0719193A - Displacement control inlet vane for fluid machine - Google Patents

Abstract

PURPOSE:To reduce clearance area at the totally closed time of an inlet vane so as to enlarge a displacement control range by forming the tip part of the inlet vane into circular arc shape, and forming a rotary shaft on the inside into spherical shape. CONSTITUTION:A fluid passes between a rotary shaft 2 and a casing 3 and rotates an inlet vane 1, supported at a casing 3, by 90 deg. to open/close it, thus adjusting the displacement of a fluid machine. In this case, the rotary shaft 2 is formed into spherical shape, and the tip part of the inlet vane 1 is formed into circular arc shape. The area of a clearance between the tip part of the inlet vane 1 and the rotary shaft 2 can be thereby made small, so that leakage from the vane part is reduced, and the flow of the fluid machine can be made small. As a result, a displacement throttling effect at the totally closed time of the inlet vane of the fluid machine can be heightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacity control inlet vane of a fluid machine, and particularly to a capacity control inlet vane suitable for expanding the capacity restriction limit when the inlet vane is fully closed in a single-shaft multi-stage centrifugal compressor or the like. Regarding

[0002]

2. Description of the Related Art FIGS. 4, 5 and 6 are views showing a conventional example. FIG. 5 is a sectional view showing the structure of FIG.
Shows a structure when the inlet vane is fully opened, 1 is an inlet vane, 2 is a rotating shaft provided in the inlet vane, and 3 is a casing which supports the shaft of the inlet vane. The fluid passes between the rotary shaft 2 and the casing 3 to rotate and open / close the inlet vane 1 supported by the casing to adjust the capacity of the fluid machine.

In the conventional inlet vane shown in FIGS. 4, 5 and 6, the rotating shaft 2 has a cylindrical shape, and when the inlet vane 1 is rotated and opened / closed, the tip of the rotating shaft 2 and the inlet vane 1 are formed. The tip of the inlet vane was straight to avoid interference. Therefore, when the inlet vane 1 was fully closed, there was a large gap in the A portion between the tip of the inlet vane 1 and the rotating shaft 2.

A related device of this kind is described in, for example, Takefumi Ikai, Blower and Compressor, page 436, published by Asakura Shoten.

[0005]

FIG. 7 shows a characteristic curve of a fluid machine with inlet vane control. The inlet vane control is a method of changing the angle of the inlet vane to give a pre-rotation in the same direction as the rotation to the absolute speed of the impeller inlet to reduce the flow rate and the pressure, and to close the angle of the inlet vane to the fully closed state. Therefore, the characteristic curve is a,
The pressure and flow rate decrease like b and c. When the inlet vane is fully closed, the characteristic curve is d. At this time, since the inlet vane is fully closed, pre-turning is not given, and the flow rate is determined by the area of the gap of the inlet vane portion and the differential pressure between the upstream side and the downstream side of the inlet vane.

The flow rate Q at this time is expressed by the following equation.

[0007]

[Equation 1]

Here, C is a constant, A is the area of the gap when the inlet vane is fully closed, and ΔP is the differential pressure between the upstream side and the downstream side of the inlet vane.

In the prior art, when the inlet vane is fully closed, the area of the gap between the tip of the inlet vane and the rotating shaft becomes large, so the area A in the above equation becomes large and the flow rate Q of the fluid machine also becomes large. The capacity squeezing effect of was smaller.

It is an object of the present invention to provide a capacity control inlet vane which is designed to expand the capacity control range of a fluid machine by reducing the area of the gap when the inlet vane is fully closed.

[0011]

In order to achieve the above-mentioned object, the present invention uses an arc at the tip of the inlet vane and makes the rotating shaft inside the spherical shape so that the inlet vane and the rotating shaft are closed when the inlet vane is fully closed. The area of the gap between them has been reduced.

[0012]

According to the present invention, the area of the gap between the vane and the rotating shaft can be reduced when the inlet vane is fully closed, and the flow rate Q can be reduced as described in the equation (1). As a result, the capacity reduction effect of the fluid machine is increased, leading to an expansion of the capacity control range.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1, 2 and 3 are views showing the structure of the inlet vane of the present invention, FIG. 2 is a sectional view showing the structure of FIG. 1, and FIG. 3 shows the structure when the inlet vane is fully opened. Reference numeral 1 is an inlet vane, 2 is a rotating shaft provided in the inlet vane, and 3 is a casing that supports the shaft of the inlet vane. Fluid is rotating shaft 2 and casing 3
The capacity of the fluid machine is adjusted by rotating the inlet vane 1 which is supported by the casing by 90 ° and opened and closed.

In the inlet vane of the present invention shown in FIGS. 1, 2 and 3, the rotating shaft 2 has a spherical shape and the tip of the inlet vane 1 has a circular arc shape so that the inlet vane 1 is fully closed. At this time, the area of the gap between the tip of the inlet vane 1 and the rotary shaft 2 can be reduced,
The flow rate of the fluid machine can be reduced. Therefore, when the inlet vane of the fluid machine is fully closed, the capacity reducing effect can be enhanced.

[0016]

According to the present invention, by reducing the leakage from the vane portion when the inlet vane is fully closed, the capacity reduction performance of the fluid machine can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the structure of an inlet vane of the present invention.

FIG. 2 is an explanatory view showing the structure of the inlet vane of the present invention.

FIG. 3 is an explanatory view showing the structure of the inlet vane of the present invention.

FIG. 4 is an explanatory view showing the structure of an inlet vane of a conventional example.

FIG. 5 is an explanatory view showing a structure of a conventional inlet vane.

FIG. 6 is an explanatory view showing a structure of a conventional inlet vane.

FIG. 7 is a characteristic diagram of a fluid machine with inlet vane control.

[Explanation of symbols]

 1 ... Inlet vane, 2 ... Rotating shaft, 3 ... Casing.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keietsu Miura 4-3, Surugadai Kanda, Chiyoda-ku, Tokyo Hitachi Techno Engineering Co., Ltd.

Claims (1)

[Claims] 1. A capacity control device for a fluid machine, characterized in that an inlet vane portion provided on an upstream side of an impeller has a rotating shaft inside the inlet vane formed in a spherical shape and an inlet vane tip portion formed in an arc shape. Inlet vane.