JPS601436A - Method of passing dangerous speed of rotating member - Google Patents

Abstract

PURPOSE:To suppress growing of vibration of a rotating member upon starting, by applying an electromagnetic force to the rotating member during increase in speed of the rotating member. CONSTITUTION:An electromagnet 9 mounted to a suitable fixing portion is located over a rotating member 7 at a short distance therefrom. When a speed of the rotating member 7 approaches a point of a dangerous speed, that is, a point A on a curve 5 during increase in speed, current is supplied to a coil 10 of the electromagnet 9. As a result, an electromagnetic attracting force of the electromagnet 9 acts in such a direction as to lift the rotating member 7, thereby reducing a bearing load of the rotating member 7. When a bearing load of a slide bearing is reduced, a spring constant in a spring action of a bearing lubricating oil tends to decrease, and accordingly a dangerous speed range of the rotating member 7 is shifted to a low speed side. Thus, it is possible to pass a dangerous speed area by generating an attracting force due to excitation of the electromagnet 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for passing dangerous speeds encountered during the speed increase process up to the rated rotational speed, ie, the normal rotational speed, without any hindrance during the start-up of a rotating machine.

In recent years, rotating machinery has become increasingly lighter and faster, and its normal rotational speed is increasingly being brought above the critical speed.

Therefore, in many cases, the engine passes through a critical speed during the process of reaching the normal rotational speed at startup.

The relationship between the amplitude of vibration and the rotational speed of the rotating body shown in Figure 1 (A) is as shown in Figure (B), and in the same figure, 1
is a rotating body, 2 is a sliding bearing that supports rotating body 1, and arrow 3 is
, 4 indicate the vertical and horizontal components of vibration, respectively, curves 5 and 6 in the same figure (b) indicate changes in amplitude in the vertical and horizontal directions, respectively, and N indicates the rated rotation speed. However, when the rotating body 1 is started up, the vertical and horizontal vibration amplitudes of the rotating body change as shown by curves 5 and 6, respectively, during the speed increase process until the rotating body reaches the rated rotational speed N.

By the way, as is clear from this relationship diagram, the amplitude of vibration in the vertical direction is usually larger than that in the horizontal direction, and the amplitude in the vertical direction is particularly problematic.

In order to protect the rotating body from the speed that causes this amplitude, that is, the dangerous speed, it is possible to suppress the growth of resonance by passing this part as quickly as possible, and one way to do this is to increase the starting torque of the drive source. Alternatively, a means for reducing the moment of inertia (GD') of the rotating part including the rotating body 1 is adopted.

However, these methods have limitations and are not sufficiently effective.

The present invention solves these problems using a simple method, and will be described in detail below with reference to FIG. 2. FIG. 2 is a schematic diagram of the apparatus used to carry out the method of the present invention. In the figure, 7 is a rotating body, 8 is an oil film spring of a sliding bearing that supports the rotating body 7, and the spring action of the oil film of the bearing lubricating oil is shown in FIG. is expressed equivalently. ) is an electromagnet and is mounted on a suitable fixed part on one side of the rotating body 7 so as to face the outer periphery of the rotating body with a small gap.

When starting the rotating body 7 in the above configuration, when the rotating body approaches the point where its speed approaches the critical speed in the process of increasing the speed of the rotating body, that is, the point A of the curve 5 in FIG. When a current is supplied to the coil 1(), the electromagnetic attractive force of this electromagnet acts in a direction to lift the rotating body 7 in one direction, and the bearing load of this rotating body is reduced.

In general, when the bearing load of a sliding bearing decreases, the spring constant due to the spring action of the bearing lubricating oil decreases (1), and as a result, the critical speed range of the rotating body shifts toward lower speeds. Therefore, if we set the binary attractive force of electromagnet L so that the 13th point on the same curve 5 is brought down to near point A, the rotating body will become dangerous as soon as this electromagnet is excited. This means that the velocity has passed through the region, and the growth of resonance is suppressed. Then, if the current of the electromagnet 9 is cut off at the point where the rotational speed of the rotating body becomes higher than the original critical speed, that is, point B of the curve 5 in Fig. 1 (b), the state returns to the same as in the normal conventional case. , enters steady operation at point N, which is the rated rotation speed.

The above explanation has been about the case where the rotating body is supported by a sliding bearing, or even if it is supported by rolling bearings such as balls and rollers, if the bearing load is small, it will be supported by this bearing. The speed of the rotating body (the corresponding critical speed range is lowered), so there is no difference in its operation and effect from the case of the sliding bearing described above.

As described above, the present invention applies an electromagnetic attraction force to one rotating body during the speed increase process of the rotating body to change the bearing load of the rotating body so that the rotating body passes the critical speed instantaneously. It is possible to suppress the growth of vibration of the rotating body during startup without reducing the moment of inertia of the motor or increasing the starting torque of the drive unit, and it is possible to start the rotating body with low vibration and without danger. end.

[Brief explanation of drawings]

Figure 1 (a) is a configuration diagram of a rotating body for explaining the conventional technology, Figure 1 (b) is a diagram showing the amplitude of vibration corresponding to the speed of the rotating body at startup, and Figure 2 is a diagram of the main body. 1 is a schematic diagram of an apparatus for explaining the invention in detail; FIG. 7... Rotating body, )... Electromagnet. Patent applicant: Kamitsuna Electric Co., Ltd. Agent: Patent Attorney: Haruya Fuji (I)! (B) (Voluntary) Procedural Amendment 1, Indication of Case 1982 Patent Application No. 108466 2
・ Title of the invention Telephone within the method for passing the dangerous speed of 1111m body Ise (36) 1111 1) In the specification, page 3, line 5, ``8 rotary body 7 supports''
Correct the statement to read "8 supports rotating body 2."

Claims (1)

[Claims] It is characterized by temporarily exciting an electromagnet provided on the stationary side during the speed increase process of the rotating body to apply an electromagnetic attraction force to the rotating body, thereby changing the bearing load of the rotating body and changing the critical speed range. A method for passing dangerous speeds of rotating objects.