JPS6289496A - Torque controller for differential actuator - Google Patents

Abstract

PURPOSE:To drive an output shaft at a constant speed in response to the rotating speed from zero speed to normal rotating speed range by controlling the rotating speed by peculiar frequency with inverter a differential mechanism and two induction machines. CONSTITUTION:Induction machines 1, 2 form together with a differential mechanism 3 a differential actuator 4. The machines 1, 2 are driven by the powers from inverters 8, 9 through peculiar distribution lines 6, 7. Thus, a constant speed is obtained at an output shaft 10 irrespective of a load torque over zero speed to a normal rotating speed range of the shaft 10 by controlling the output frequencies of the inverters.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention consists of two induction machines and a differential mechanism [Prior Art] Fig. 7 shows a conventional induction machine used as an actuator. It is an inverter control circuit diagram, and in the figure, 5
1 is the input terminal of the AC power supply, and 52 is the input terminal for the AC power supply. 53 is a smoothing circuit that smoothes the converted DC; 54 is a DC-AC converter (hereinafter referred to as an inverter) that converts DC into AC power of an arbitrary frequency; 5
5 is an induction machine.

Next, the operation will be explained.

First, the AC-DC converter 52 converts, for example, a three-phase AC power source into DC, and after smoothing this in the smoothing circuit 53,
The inverter 54, which turns on and off in a fixed sequence, converts it into an alternating current voltage of any desired frequency, which is input to the induction machine 53.

Therefore, the rotational speed of the induction machine 55 is controlled by receiving the voltage/frequency output from the inverter 54 as shown in FIG.

Also, by using the inverter 54 as described above, the voltage/
By changing the frequency characteristic (CV/f characteristic), that is, by making the output voltage ■ proportional to the output frequency f of the inverter 54, a nearly constant torque characteristic can be obtained, and by changing the frequency r, the voltage ■ If is controlled to be constant, approximately constant output characteristics can be obtained.

[Problems to be Solved by the Invention] The conventional control method using the inverter 54 for the induction motor is as described above. It is necessary to appropriately change the set frequency of each inverter 54 for each induction machine depending on the magnitude of the
As shown in the figure, in addition to not being able to obtain sufficient torque, there is a limit to the frequency generated by the inverter 54, making it impossible to control the rotational speed.

This invention was made to solve the problems listed in L. A differential actuator, which is a combination of two induction motors and a differential mechanism, is controlled by an inverter, and the output shaft can be changed from zero speed to normal speed. It is an object of the present invention to obtain a rotational speed control method for a differential actuator that can obtain a constant rotational speed on an output shaft over a rotational speed range in relation to load torque.

[Means for solving problems]

The rotational speed control method of a differential actuator according to the present invention is set by each inverter provided correspondingly to each induction machine of the differential actuator consisting of two induction machines and a differential mechanism. A frequency power source is supplied, and a constant rotational speed corresponding to the difference between these set frequencies is obtained on the output shaft.

[Effect]

The inverter control of the differential actuator in this invention selects the difference between the set frequencies of two inverters, and adjusts the output shaft to zero regardless of the load torque by increasing or decreasing the set frequency difference. It acts to provide constant control over a wide range from speed to normal operating speed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, reference numerals 1 and 2 indicate induction machines having the same output characteristics and the same structure, and these constitute a differential actuator 4 together with a differential mechanism 3, which will be described later.

The induction machines 1 and 2 receive power from the same three-phase AC power supply 5 via their own distribution lines 6 and 7, and here each induction machine has the voltage/frequency characteristics shown in Figure 1O. It is driven by receiving power from inverters 8 and 9. IO is an output shaft of the differential actuator 4, which is equipped with a digital torque detector 11 so that the detected torque value can be displayed on a torque meter 12.

The data detected and measured by the digital torque detector 11 and other circuit current, voltage, and power measuring instruments can be monitored at any time on a display device such as a control panel. Further, 13° and 14 are multiphase power sources input to the distribution line 6.7.

FIG. 2 is a structural diagram showing details of the differential actuator 4. As shown in FIG. In the figure, reference numeral 1.2 denotes an induction machine, which are connected by a differential mechanism 3 and housed in the same case 21. 22 and 23 are hollow rotating shafts of the induction machines 1 and 2, which are rotatably supported by bearings 24 and 25, respectively.

26.27 are the first . A second differential gear, 28.29, is a third differential gear, 3, meshed together with both of these differential tooth types 26.21.
0 is a differential shaft installed on the third differential gear 28 and 29, 31 is a differential bearing that rotatably supports this differential shaft 30, and 32 and 33 are orthogonal to the differential shaft 30. projecting output shafts which pass through the hollow rotating shaft 22,23;
It is rotatably supported by bearings 34 and 35 provided at the open end of the case 21.

Next, the operation of this differential actuator 4 will be described, and then the method of the present invention will be described according to the circuit shown in FIG.

First, the rotating shafts 22 and 23 move toward the differential mechanism 3 by arrows P,
When rotating in the Q direction, if the rotational speed θ1 of the rotational shaft 220 is greater than the rotational speed 02 of the rotational shaft 230, (θ
1>θ2), based on these rotational speed differences, the third differential gears 28 and 29 revolve around the tenth differential gear 26 and the second differential gear 27 while rotating around the differential wheel 30. do. Therefore, the output shafts 32 and 33 are R
It rotates in the direction, and its rotational speed is . Furthermore, if the rotational speed of the rotational shaft 22 is lower than the rotational speed of the rotational shaft 23, that is, if θ1<θ2, the third Z' drive gear 2829 receives the same rotation of the second differential gear 27, and the IJ As shown in FIG. Next, if the rotational speeds of the rotating shafts 22 and 23 are both equal (θ1-θ,), then θo-0, the difference in the rotational speeds of the output shafts 32 and 33 becomes zero, and the output shafts 32 and 33 immediately stop.

In this way, even if the two rotating shafts 32, 33 are used within the normal rotation speed range, the output shafts 32, 33 can smoothly or easily rotate from zero speed to a predetermined low speed. In other words, it becomes easier to shift gears in the low-speed co-rotation region.

Next, when the rotational direction of one of the two rotational shafts 22.23, for example the rotational shaft 23, is reversed (in the direction of arrow S), the rotational speed of the output shaft 32.33 at this time will be the first. The rotational speeds of the second differential gears 26 and 27 add together and θ. -Ding(θ1+θ2) ・・・・・・・・・・・・
...(2), and the speed will be increased. Also, the rotational speed θ1. If both θ7 are made equal, (θ1−
θ2), the third differential gear 28,29 is the first differential gear 28,29. The second differential gear 26, 2Ll- does not rotate; The output shaft 32.33 rotates integrally with the second differential gear 26.27, and the rotational speed of the output shaft 32.33 obtained at this time is equal to the rotational shaft 22. It becomes something.

(Thus, the speed change range of the output shaft of this differential actuator 4 is a wide range including zero speed, i.e. -(θ, +
θ2)〈θ. 〈Juo (θ1 + θ2)・Old Be 3).

'jJ? 'a Conductor 11. Each output torque of 12 is ``r,''
r”.

and the output l/lux of the output shaft 32.33 is T. Then, between these, there is always T, = T, + T, ・・・・・・・・・・・・・・・
・The relationship (4) is established, and the output torque 'l'l, T'
2 is balanced, T,=27, and sufficient torque is obtained at the output shaft 32,33.

Next, a case will be described in which the rotational speed of the output shafts 32 and 33 is controlled to a desired constant value. First, operate the frequency setting knob etc. to change the frequency output by each inverter 8.9, and thereby adjust the set frequency of each inverter 8.9 to the frequency-voltage characteristic shown in FIG.
z to 50t (set the frequency within the frequency range of z, and further increase or decrease the difference in the set frequency. By doing this, as shown in FIG. 3, regardless of the magnitude of the load torque, the output shaft 32. 33 can be kept constant. For example, the rotation speed of the output shafts 32 and 33 can be set to 26 rpm.
m, the set frequencies of the two inverters 8.9 should be set to 35Hz and 3311z, 36H2 and 32t+z, 3711z and 31Hz, etc., depending on the value of the load torque. If you make one higher and the other lower, the respective frequency differences will be 2Hz, 4Hz,
The rotation speed corresponding to 5Hz... is the output shaft 32.33
can be obtained. This means that when the output shaft 32.33 is held at a certain rotation speed, it is only necessary to change the set frequency of each inverter 8.9 near the periodic speed of the induction machine. It also becomes easier to control the rotation speed. In addition, in Fig. 3, two inverters 8 and 9 are connected so that the output rotational speed becomes constant by tightening the pronibrake.
This shows the case where the set frequencies of are changed at the same time.

FIG. 4 shows an example in which the rotational speed control method of the present invention is applied to a main shaft 41 of a machine tool. According to this, by screwing the main shaft 41 to the output shaft 42 of the differential actuator 4, the main shaft 41 can be brought close to the workpiece 43 at a constant speed regardless of the magnitude of the torque, and the desired result can be achieved. You can execute T-works.

FIGS. 5(a) and 5(b) similarly show an example in which this rotational speed control method is used for the joint portion 45 of the robot 44 body. According to this C1-, the difference 111 type actuator 4
The motor 46 connected to the output shaft 42 can be operated at any speed IW including zero speed.

Figure 6 shows work 43 moving Desol 47L! ! The mounted table 48 is horizontally moved by the rotation of the output shaft 42! It shows the , = 4'+, the mounting table 48 can be moved in the range from zero-speed IW to 1 ftl normal speed jα (
＋Can be set as desired, ■11 If it is easy to link 11 machines, 1
-7 points.

〔Effect of the invention〕

As described below, according to the present invention, the rotational speed of the two induction machines constituting the differential actuator together with the differential mechanism is controlled by one inverter at a unique (h1) wave number, and the output shaft is thereby controlled. The rfL can be set freely regardless of the load torque, since it is possible to drive in the range of 11 rotations from zero speed at a constant speed corresponding to the difference in these rotation speeds.
It has the effect of reducing the amount of rotation j * degrees to a workpiece such as T machine 4 (etc.) by 1%.

[Brief explanation of drawings]

Fig. 1 is a one-piece connection diagram for explaining the rotational speed control method of a differential actuator according to an embodiment of the invention according to ζ and t; Fig. 2 is a sectional view of the differential actuator; For example, differential actuator torque vs. rotational speed Il
! f+l1-1'ul, Fig. 4 is a front view of the main shaft of the T machine tool using the rotational speed control system of the present invention, Fig. 5 is a front view of the r:2 pot joint, and Fig. 6 is the same. A front view of the table control device, Fig. 7 is a conventional induction machine inverter control circuit, and Fig. 8 is an inverter voltage/1h1 wave number 1.
, iTakezono, Figure 9 is a conventional torque-rotational speed characteristic +'1 diagram. 1.2 is an induction machine, 3 is a differential mechanism, 4 is a differential actuator, and 8 and 9 are inverters. Note that in the figures, reference numbers indicate the same or corresponding parts.

Claims (1)

[Claims] It is equipped with two induction machines and a differential mechanism that extracts the sum or difference of the rotational speeds of each of these induction machines and transmits it to an output shaft, and the output shaft is adjusted according to the rotational speed of each of the induction machines. In a differential actuator rotational speed control system that controls the rotational speed of A rotational speed control method for a differential actuator, characterized in that a rotational speed is obtained according to the frequency difference set above.