JPS6238954B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In order to drive a large inertial machine that is decelerated by a motor, in addition to the main driving motor, at the time of starting, a small linear motor exclusively for starting is used on the low speed shaft. Concerning improvements in economical operation by reducing the output of the engine to continuous operation output.

To start a large inertial machine with a motor, the size of the motor is determined based on the heat capacity that can be stored in the rotor, and the size is larger than the output determined from continuous operation. Figure 1 shows a conventional starting method for starting a rotating body with a moment of inertia G (Dm) ² from rotational speed O to n. In the figure, a pulley 3 is fitted onto the shaft end of a large inertial machine 1. A driving/operating motor 2 (hereinafter referred to as a driving motor) is installed parallel to the inertial machine 1, and a pulley 3a having an outer diameter smaller than the pulley 3 is fitted onto the shaft end.
The pulleys 3 and 3a are connected by a belt, and the inertial machine 1 is operated at a reduced speed by the driving motor 2. At this time, the amount of heat accumulated in the rotor of the inertial machine 1 is Q = 3.3 x G (Dm) ² x n ² x 10 ^-4 cal. If the allowable rotor calorific value Q ₁ is smaller than Q as the operating load L ₁ K _w , it is necessary to use a large motor L ₂ K _w corresponding to this. Therefore, when using a large inertia machine 1 at reduced speed, the moment of inertia is G (Dl) ² and the rotation speed is
As nl, convert the rotation speed nm of the two drive motor axes into the drive motor shaft, and let this be G(Dm) ² , then G(Dm) ² = G(Dl) ² × (nl/nm) ² . Letting the moment of inertia of the driving motor 2 be GD ² , when this ratio G(Dm) ² /GD ² ≧1000 is reached,
Simply increasing the capacity of the driving motor 2 is not economically advantageous.

When the G (Dm) ² / GD ² ratio increases in this way, there are disadvantages such as the need to increase the capacity of the operating motor 2 for starting and use it in an inefficient location where the load is light during operation. . To compensate for these drawbacks, there is a method that uses a mechanical centrifugal force clutch to start while sliding the torque transmission surface, but the
If (Dm) ² /GD ² is large, the transmission surface of the clutch will wear out in a short period of time. Therefore, a non-contact, economical starter was needed.

In order to eliminate such drawbacks, the present invention provides a starting motor that is small in size and has a large allowable heat capacity that can absorb the amount of heat that exceeds the allowable rotor heat capacity of the motor, and a motor that has a capacity that matches the load during operation. The purpose of this invention is to provide a method for starting a high moment of inertia rotating machine using a linear motor.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 5. However, the same parts as in the past are given the same reference numerals. FIG. 2 is a block diagram of a starting method according to an embodiment of the present invention, and FIG. 3 is a front view of a linear motor rotor. In the figure, a pulley 3 is fitted onto the shaft end of a large inertial machine 1, and a rotor 5 having a radius R and a U-shaped cross section is attached to the end face of the pulley 3 on the opposite side of the inertial machine 1. A starting motor 7, which is a linear motor, is formed by arranging iron cores 4, each of which has a coil 6 wound around a part of its outer periphery, facing each other. As for the size of the starting motor 7, an arc angle θ is selected that provides good characteristics for obtaining a predetermined rotational speed n1 for the rotor 5 having a radius R. Further, a driving motor 2a having a smaller operating output than the conventional motor is installed in parallel with the inertial machine 1, and a pulley 3b having a diameter smaller than the outer diameter of the pulley 3 is fitted to the shaft end. The pulleys 3 and 3b are connected by a belt.

The moment of inertia of the inertia machine 1 is G(Dl) ² , and the number of rotations is nl. Further, the moment of inertia of the driving motor 2a is Ga (Da) ² and the rotation speed is nm. The speed/torque curves of the starting motor 7 and the driving motor 2a are shown in curves 8 and 9 in FIG. 4, respectively. Next, the startup method of this embodiment will be explained. First, it is confirmed that the rotational directions of the starting motor 7 and the driving motor 2a are the same, and then the power is turned on. Then, the linear motor of the starting motor 7 has a large starting torque, so the low-speed shaft is turned off.
When it starts up to n1 rotation, the power is cut off. The rotational speed of the driving motor 2a at that time is as shown in Fig. 5.
It increases to n ₁ ×nm/nl. Further, when the driving motor 2a is rotated to nm, the rotational speed of the inertial machine 1 is also increased to nl. The above-mentioned rotational speed in the speed-torque curve of the starting motor 7 and the driving motor 2a at this time
The relationship between n1×nm/nl and nm is as shown in FIG. In this way, the starting motor 7, which has a large starting torque, takes over the task of starting the inertial machine 1, and during the start of the inertial machine 1, and during operation, the starting motor 7, which has good operating characteristics, takes over the task.
Due to the sharing of part a, starting can be completed in a short time. In addition, the moment of inertia Ga (Da) ² of the driving motor 2a itself,
Load inertia moment G converted to operating motor shaft
(Dm) ² is applied to the driving motor 2a at startup. The total amount of heat generated to start up the inertial machine 1 is Qt = 3.3.
×{Ga(Da) ² +G(Dm) ² }n ² ×10 ^-4 cal,
If the allowable calorific value of the operating motor 2a is Qm (with a rotational speed from n ₁ nm/nl to nm), the difference from the total starting calorific value Qt is distributed to the starting motor 7 by Qs = Qt - Qm. (with rotational speeds from 0 to nl). This results in 3.3×{G(Dl) ² +Ga(Da) ²
×(nm/nl) ² }n ₁ ² ×10 ^-4 cal is the starting motor,
3.3 × {G(Dm) ² +Ga(Da) ² }{(nm) ² −(n×nm/
nl) ² }×10cal is the amount of heat generated by each driving motor 2a. In other words, when the total starting heat generation is shared between the starting motor 7 and the driving motor 2a, the iron core weight of the driving motor 2a is 20 to 30% as compared to the conventional motor due to the reduction in heat generation due to the short time starting. The amount of winding is reduced and the size is significantly reduced.

This starting motor 7 may be attached to either the low-speed shaft or the high-speed shaft, but the advantage of attaching it to the low-speed shaft is that the arc angle θ in the design of the linear motor can be made smaller. The rotation speed of the linear motor is 60τp/πR (where τ
p is the pole pitch of the coil, is the power supply frequency, and R
Since the radius R cannot be made larger due to the surrounding dimensional conditions and economical considerations, the rotational speed is controlled by the pitch τp. Even if you try to increase the rotation speed, use a two-pole winding and increase the pole pitch τp of the coil, that is, in the extreme case where the arc angle θ is large, θ>
It becomes 180°. This is the configuration of the machine, the storage of the windings,
The formation of poles becomes disadvantageous and the characteristics deteriorate. On the low-speed axis, even if the poles of the linear motor are made large, the pole pitch τp and the arc angle θ can be made small, making it possible to design a machine that is compact and has good characteristics. For these reasons, the linear motor used as the starting motor 7 is not suitable for high speed operation, and is better installed on a low speed shaft.

Furthermore, the moment of inertia of the low-speed shaft is larger than that of the motor shaft at startup, but the arc angle θ of the linear motor
It is also possible to increase the core thickness without changing.
In addition, the linear motor itself has more contact with the outside air than the aluminum cast rotor induction motor. Fewer parts are covered by the stator. Must be larger than the rotor diameter of the driving motor. Do not use materials with low melting points such as aluminum. This is not a problem because the heat capacity can be extremely large due to good cooling.

Also, in the current curve shown in Fig. 4, the operating motor 2
By combining the starting current 10 of the starting motor 7 with the starting current 11 of a, it is not necessary to change the settings of the contactors and thermals of the power supplies used for both.

Further, after the start is completed, the power to the starting motor 7 is cut off and there is no contact, and the driving motor 2a is smaller and lighter than the conventional motor, reducing mechanical loss. Furthermore, since the linear motor can also be used for braking when stopped, it can be stopped in a short time, with less danger and good heat dissipation.

In this way, this embodiment takes advantage of the characteristics of the driving motor and the linear motor used for starting to rationally allocate the starting heat, plans the appropriate size of each motor, and makes it efficient and non-contact. Since the starter does not have a bearing, it provides a two-stage starting method with a low-speed shaft that is superior in terms of maintenance.

The starting motor 7 is attached to the low-speed shaft, and the rotor 5
Since the rotor 5 can be designed and manufactured from steel, a part of the machine can also be used for the rotor 5.

As mentioned above, in a machine that decelerates a large inertial body using a motor, a linear motor with good starting characteristics and ease of maintenance is installed on the low-speed shaft, and all starting heat is rationally distributed to both the driving motor and the linear motor used for starting. By distributing the starting power and starting in two stages using both motors, the capacity of the operating motor can be reduced and a starting method that is more reliable and more economical than the conventional method can be achieved.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a conventional starting method, Fig. 2 is an explanatory diagram of the configuration showing an embodiment of the present invention, Fig. 3 is a front view of the linear motor rotor in Fig. 2, and Figs. FIG. 5 is a characteristic diagram. 1... Inertia machine, 2, 2a... Drive/operation motor, 7... Starting motor.

Claims (1)

[Claims] 1. In a device in which a large rotating inertial machine is decelerated by a driving motor, the rotor diameter of the decelerating inertial machine is larger than the rotor diameter of the driving motor, and the stator is configured to surround only a part of the rotor. 1. Starting a high-inertia rotating machine, characterized in that a starting motor consisting of a linear motor is provided, the starting motor first accelerates the machine, and from an arbitrary rotation point, the operating motor rotates the machine to a steady rotation speed. Method.