JPS5840680B2 - Variable pitch axial flow fan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The schematic structure of a conventional rotor blade variable pitch axial flow fan will be explained with reference to FIG. The impeller 3 is driven one time via the impeller side plate 2.

A plurality of moving blades 4 are attached to the outer periphery of the impeller 3 to rotate together with the impeller 3, and the moving blades 4 blow air in the direction of arrow A.

Stator blades 5 are fixed to the casing and serve to rectify the air flow sent by the rotor blades 4 to improve the efficiency of the fan.

The impeller 3 is fixed with a key 9 to one end of a main shaft 8 supported by bearings 6 and 7, and the other end of the main shaft 8 is connected to a hydraulic cylinder 8.
It is a.

Although a detailed explanation of the structure of this hydraulic cylinder section will be omitted, the axial movement of the pilot spool 11 is caused by the hydraulic pressure introduced from the hydraulic oil hose 10 to the piston 1.
The structure is such that the force is increased by the pressure receiving area of the piston 12 and the pressure of the oil.

In other words, it is a follow-up boosting mechanism. The rod portion 12a of the piston 12 passes through the hollow part of the main shaft 8, and an actuating plate 13 is attached to the blade wheel 3 so that it is located at the center of the blade. Although variations are possible, this structure is described in detail in FIGS. 2-4.

In the figure, when the piston rod portion 12a1 actuating plate 13 moves in the axial direction, the piece 14 fitted in the U-shaped groove 13a on the outer periphery of the actuating plate 13 also moves in the axial direction.

The piece 14 is swingably fitted into a pin portion at the tip of an arm 15, and the arm 15 is connected to a rotor blade shaft 16 by a spline at its center.

FIG. 4 is a sectional view taken along the line C-C in FIGS. 2 and 3 when this part is viewed from the outer circumferential direction toward the center of rotation, and the movement of the actuating plate 13 in the axial direction is in the direction of the y dimension in FIG. It is.

When the joint plate 13 moves by y in the axial direction, the arm 15 rotates by an angle θ about the rotor blade axis spline as shown by the two-dot chain line.

Then, a phase slip of X occurs between the bridge 14 and the groove 13a of the actuating plate 13.

From the above, it can be seen that it is desirable to have no relative rotation between the cylinder 8a and the piston 12, and between the actuating plate 13 and the piece 14, in terms of wear, heat generation, stickiness, etc.

For this purpose, a pin 17 is provided so that the main shaft 8 and piston 12 rotate together.

This pin 17 is supported at both ends by the impeller 3 and the side plate 2, and passes through the actuating plate 13 at an intermediate portion so as to be able to slide in the axial direction.

However, according to this structure, when the rotation speed is increased to improve the performance of the fan, or because the light metal blades cannot be used to pass high temperature gas or gas mixed with fine solid particles, heavy metal blades are used. In this case, the centrifugal force becomes extremely large, and even though the friction coefficient is reduced by the ball bearing 18, the rotational resistance force of the rotor blade shaft 16 becomes large.

That is, the force between the actuating plate 13 and the piece 14 becomes a force, and the sliding resistance of the dimension X caused by the rotation angle θ of the arm 15 becomes abnormally large.

Note that the slip resistance force X is a force that tends to cause relative rotation between the impeller 3 and the actuating plate 13, and this force is directly applied to the pin 17.

Therefore, there is a risk that the pin 17 may be bent or broken, and the relative movement of the pin 17 and the actuating plate 13 in the axial direction becomes difficult, resulting in malfunction.

An object of the present invention is to obtain a rotor blade variable pitch axial flow fan that uses a torque limiter to eliminate the above-mentioned conventional drawbacks such as pin breakage and malfunction. It is something to do.

In order to achieve this object, the present invention comprises a main shaft rotatably supported, a blade wheel coupled to the main shaft and connected to a rotational drive mechanism, and a plurality of rotor blades attached to the outer periphery of the blade wheel. and an inner assembly consisting of a piston rod that is reciprocably inserted into the main shaft and has an actuating plate fixed to its tip. In a rotor blade variable pitch type axial flow fan, the rotor blades are connected in such a way that a piece that is swingably fitted into the arm moves integrally in the axial direction, but rotation is not transmitted at that part. The inner and outer assemblies are rotated through a torque limiter consisting of a hub connected to the piston rod, a transmission plate that rotates integrally with the impeller but is freely movable in the axial direction, and a spring that presses a friction plate against both. Under normal operating conditions, the outer assembly and the inner assembly rotate together through a torque limiter, but the contact force between the bridge and the actuating plate increases, causing relative rotation. Even if a shift occurs, the shift in the rotation angle is so slight that the torque limiter will not slip and the disadvantages described above will not occur.

As described above, since the present invention uses a torque limiter, there is no need to force the bridge to slide in areas where there is high surface pressure, such as the contact area between the bridge and the actuating plate, which may cause wear, heat generation, sticking, etc. In addition, when a large force acts between the inner and outer assemblies and a relative rotational movement occurs, the relative rotational movement should be caused to an extent that does not cause any problems without forcibly resisting.

The present invention also does not have a part that forces the inner and outer assemblies to turn together like the conventional pin, so there are no drawbacks such as bending or breaking the pin or malfunction when changing the blade angle. do not have.

[Brief explanation of the drawing]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiments of the present invention shown in FIGS. 5 and 6, parts that are the same as those in the prior art are designated by the same reference numerals. Now, Fig. 5 is a cross-sectional view corresponding to Fig. 2, and the impeller 3
, the pin 17 shown in FIG. 2 that connects the outer assembly consisting of the rotor blades 4 and the main shaft 8 and the inner assembly consisting of the operating plate 13 and the piston rod 12a for synchronous rotation does not exist in FIG. A torque limiter constituted by a replacement hub 19, a nut 20, a disc spring 21, and a transmission plate 22 is interposed between the inner and outer assemblies. In this mechanism, a disc spring 21 is pressed down by a nut 20 screwed onto a hub 19, and this force clamps a transmission plate 22 to provide a frictional force. In addition, a shoe that allows dry sliding is provided on the surface of the transmission plate 22 that presses the friction surface, and when a torque of a certain value or more is applied, the shoe slides on this surface. Further, the torque limiter can be a general commercially available one, and is attached to the tip of the piston rod 12a with a key 23, and the transmission plate 22 meshes with the outer side plate 2 as shown in FIG. However, this meshing portion is slidable in the axial direction. Further, 24 is a nut for fixing the hub 19 to the piston rod 12a. In addition, in the figure, flange coupling 1, piece 14, arm 1
5. The rotor blade shaft 16 and ball bearing 18 have the same structure as the conventional one. Next, to explain the operation, in a steady operating state, the outer assembly and the inner assembly rotate together through the torque limiter. FIG. 6 is a side sectional view showing the main parts of a rotor blade variable pitch type axial flow fan showing an embodiment of the present invention.
-D sectional view. Explanation of the main parts of the diagram, 3... impeller, 4...
... Moving blade, 8 ... Main shaft, 12a ... Piston rod, 13 ... Actuation plate, 19 ...
Hub, 20...nut, 21...disc spring, 22...transmission plate, 23...key.

Claims (1)

[Claims] 1 A rotatably supported main shaft, a blade wheel coupled to the main shaft and connected to a rotational drive mechanism, an outer assembly consisting of a plurality of rotor blades attached to the outer periphery of the blade wheel, and a reciprocating motor within the main shaft. An inner assembly consisting of a piston rod that is movably inserted and has an actuating plate fixed to its tip is swingably fitted into an arm splined to the rotor blade shaft in a U-shaped groove provided in the actuating plate. In the variable pitch type axial flow fan, the rotor blades are coupled so that they move together in the axial direction by fitting the piston rod, but do not transmit rotation at the same portion, the hub coupled to the piston rod; The inner and outer assemblies are rotatably connected via a transmission plate that rotates integrally with the impeller but is freely movable in the axial direction, and a torque limiter made of a spring that presses a friction plate against both. A rotor blade variable pitch axial flow fan.