JPH061996B2 - Torque control device for differential actuator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a torque control device for a differential actuator that controls output torque of a differential actuator including two induction machines and a differential mechanism.

[Prior Art] FIG. 9 is a control circuit diagram of an inverter of an induction machine used as a conventional actuator.
1 is an input terminal of an AC power supply, 52 is an AC-DC converter that converts AC into DC, 53 is a smoothing circuit that smoothes the converted DC, and 54 is DC-AC that converts DC into AC power of an arbitrary frequency. Converter (hereinafter referred to as inverter), 55
Is an induction machine.

Next, the operation will be described.

First, the AC-DC converter 52 converts, for example, a three-phase AC power supply into DC, smoothes it with a smoothing circuit 53, and then turns it on and off in a fixed sequence by an inverter 54, which has an AC of a desired arbitrary frequency. It is converted into a voltage and input to the induction machine 55. Therefore, the induction machine 55 receives the voltage / frequency output as shown in FIG.

Also, using the inverter 54 as described above, the voltage /
By changing the frequency characteristic (V / f characteristic), that is, by making the output voltage V proportional to the output frequency f of the inverter 54, a nearly constant torque characteristic can be obtained, and even if the frequency f changes, the voltage V remains unchanged. When controlled to be constant, almost constant output characteristics can be obtained.

[Problems to be solved by the invention]

Since the conventional control method by the inverter of the induction machine is as described above, in the normal operating state, as shown in FIG. 11, torque control is possible except in the low speed rotation region, but from zero speed to this region. In the low speed rotation speed range, the torque ripple becomes large and a sufficient and stable torque cannot be obtained. Therefore, there is a problem that the torque control of the induction machine is impossible in this rotation speed range.

The present invention has been made in order to solve the above-described problems, and it is an inverter control of a differential actuator that is a combination of two induction machines and a differential mechanism so that the output shaft is rotated at a normal speed from a zero speed. An object of the present invention is to obtain a torque control device for a differential actuator, which is capable of outputting a sufficiently large torque over a range.

[Means for solving problems]

A torque control device for a differential actuator according to the present invention uses each of the above induction machines of a differential actuator including two induction machines and a differential mechanism, and uses an inverter provided corresponding to each of the induction machines. The drive is controlled.

[Action]

One of the induction machines in the present invention is driven by an inverter having a constant output frequency, and the other induction machine is driven by an inverter capable of selecting an arbitrary output frequency, so that the output shaft is changed from zero speed to a normal rotation speed region. It acts to obtain a constant torque across. This is due to the differential characteristics of the differential mechanism capable of driving the output shaft at zero speed even when the above-mentioned induction machines rotate at high speed, and at the same time prevents the occurrence of torque ripple. Further, if the output frequency of the inverter input to each induction machine is arbitrarily set, the rotation direction of the output shaft can be reversed, and a desired torque can be freely obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, reference numerals 1 and 2 denote induction machines having the same output characteristics and the same structure, which constitute a differential actuator 4 together with a differential mechanism 3 described later. The induction machines 1 and 2 are supplied with electric power from the same three-phase AC power source 5 through their own power distribution lines 6 and 7, and here, each of them has a voltage / frequency characteristic shown in FIG. It is driven by receiving electric power from the inverters 8 and 9. Reference numeral 10 denotes an output shaft of the differential actuator 4, to which a digital torque detector 11 is attached, and the detected torque value can be displayed by a torque meter 12. Each detection and measurement data by the digital torque detector 11 and other circuit current, voltage, and power measuring devices can be monitored at any time by a display device such as a control panel. Also,
Reference numerals 13 and 14 are polyphase power meters placed in the distribution lines 6 and 7.

FIG. 2 is a structural diagram showing the details of the differential actuator 4. In the figure, reference numerals 1 and 2 denote induction machines, which are connected by a differential mechanism 3 and housed in the same case 21. Reference numerals 22 and 23 denote hollow rotary shafts of the induction machines 1 and 2, which are rotatably supported by bearings 24 and 25, respectively. 26 and 27 are hollow rotary shafts 22 and 2
First and second differential gears, 28, 2 attached to three ends
Reference numeral 9 is a third differential gear meshed with both differential gears 26 and 27, and 30 is the third differential gears 28 and 29.
, 31 is a differential bearing that rotatably supports the differential shaft 30, and 32 and 33 are output shafts that project so as to be orthogonal to the differential shaft 30. Rotating shaft 2
It is rotatably supported by bearings 34 and 35 which penetrate the insides of the cases 2 and 23 and are provided at the open ends of the case 21.

Next, the operation of the 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 rotary shafts 22 and 23 are attached to the differential mechanism 3 by arrows P,
When rotating in the Q direction, the rotation speed θ ₁ of the rotating shaft 22 is set to be higher than the rotation speed θ ₂ of the rotating shaft 23 (θ ₁
> Θ ₂ ), the third differential gears 28, 29 rotate on the differential shaft 30 and rotate on the first differential gear 26 and the second differential gear 27 based on the rotational speed difference. Revolve around. Therefore, the output shafts 32 and 33 are R
The rotation speed is θ ₀ = 1/2 (θ ₁ −θ ₂ ) ... (1). Further, when the rotation shaft 22 is lower than the rotation speed of the rotation shaft 23, that is, when θ ₁ <θ ₂ , the third differential gears 28 and 29 are adapted to receive the rotation of the second differential gear 27. And revolves on the first differential gears 26 and 27 in the opposite direction to the above, and the output shafts 32 and 33 rotate in the opposite direction to the above. Next, assuming that the rotation speeds of the rotation shafts 22 and 23 are both equal (θ ₁ = θ ₂ ), θ ₀ = 0, and the rotation speed difference between the output shafts 32 and 33 is zero, that is, stops.

As described above, even when the two rotary shafts 32 and 33 are used in a normal rotational speed range, the output shafts 32 and 33 can smoothly and easily obtain a predetermined low speed rotation from zero speed. That is, shifting in the low speed rotation region becomes easy.

Next, when the rotation direction of one of the two rotation shafts 22 and 23, for example, the rotation shaft 23 is reversed (arrow S direction), the rotation speeds of the output shafts 32 and 33 at this time are the first and second rotation speeds. The rotational speeds of the differential gears 26 and 27 are added to each other, resulting in θ ₀ = 1/2 (θ ₁ + θ ₂ ) (2), and the speed is increased. Also, the rotation speed θ ₁ ,
If both θ ₂ are made equal (θ ₁ = θ ₂ ), the third
Differential gears 28, 29 of the first and second differential gears 26, 2
7, the first and second differential gears 26, 2
The rotation speed of the output shafts 32 and 33, which rotate integrally with the motor 7, is equal to that of the rotation shafts 22 and 23, and the output is the sum of the outputs of the induction machines 11 and 12.

Thus, the speed change range of the output shaft of the differential actuator 4 is a wide range including zero speed, that is, -1/2 (θ ₁ + θ ₂ ) <θ ₀ <+1/2 (θ ₁ + θ ₂ ) ... … (3).

On the other hand, assuming that the output torques of the induction machines 11 and 12 are T ₁ and T ₂ and the output torques of the output shafts 32 and 33 are T ₀ , T ₀ = T ₁ + T ₂ ... When the relationship of (4) is established and the output torques T ₁ and T ₂ are balanced and the torque is T, T ₀ = 2T, and a sufficiently large torque can be obtained at the output shafts 32 and 33.

Next, the torque of the differential actuator 4 is set to the first
A control method using the circuit shown in the figure will be described.

First, regarding the relationship between the rotational speeds and torques of the output shafts 32 and 33 of the differential actuator 4, the set frequencies of the inverters 8 and 9 are 35 Hz and 30 Hz (frequency difference 5H, respectively).
z), the rotation speed of the induction machines 1 and 2 is 937 RPM,
According to the experiment, the solid line in Fig. 3 is obtained, and the maximum generated torque reaches 29.6 Kgcm. As in the conventional case, the maximum generated torque 4.7 when the single induction machine is driven at the set frequency is shown. It is much larger than Kgcm. This means that by controlling the differential actuator 4 by an inverter, a sufficiently large torque is generated even in the low speed rotation speed range, and it is sufficiently practical.

Moreover, the set frequency of the inverter 8 is fixed to 3.5 Hz,
When the set frequency of the other inverter 9 is changed between 5 Hz and 30 Hz, the torque-rotation speed characteristic as shown in FIG. 4 is obtained and the drooping characteristic similar to that of the DC machine is exhibited. That is, the speed control ratio can be made sufficiently large. According to this, for each set frequency to be changed, a sufficiently large torque can be obtained by controlling a small number of revolutions, and in a differential actuator that is a combination of two DC machines,
It also corresponds to the case where the difference in voltage applied to each DC machine is changed.

Next, a load is applied to the output shafts 32 and 33 by, for example, a brake to set the set frequency of the inverter 8 to a constant 35 Hz and the set frequency of the inverter 9 is changed. The torque-rotation speed characteristic is as shown in FIG. 5, and the torque can be controlled to be substantially constant regardless of the rotation speed.

In this way, the output shafts 32, 3 of the differential actuator 4 are
Even when 3 rotates at a low speed, the induction machines 1 and 2 constituting this rotate at a high speed.
Nos. 2 and 33 can generate a sufficiently large torque even during low speed rotation, and the torque ripple is also extremely small.

FIG. 6 shows a gripper using the torque control device of the present invention, which is a horizontally movable nut member 41 screwed into a screw portion 33a formed on the output shaft 33 of the differential actuator 4, and this nut member 41. Two arms 42 each having one end pivotally supported, a grip arm 43 having one end pivotally supported on the case of the induction machine 2 and the other end of the arm 42 pivotally supported at a central portion, and each grip arm It is composed of a grip plate 44 projectingly provided at the 43 end so as to face each other. This gripper allows the work 45 to be sandwiched between the grip plates 44 by an arbitrary force by the torque control of the differential actuator 4 as described above.
But you can grab it without damaging it. Further, due to the characteristics of FIG. 5, the work 45 can be moved from one side to the other with a constant clamping force regardless of the moving speed of the work 45, for example.

FIG. 7 shows a work extrusion device of various automatic machines utilizing a torque control device. This is one in which a nut member 46 is horizontally movably screwed into a screw portion 33a formed on the output shaft 33 of the differential actuator 4, and an L-shaped pushing rod 47 is integrally attached to the nut member 46. The rotation of the output shaft 33 causes the pushing rod 47 to push the work 48 to one side on the bed 49. According to this, for example, a high torque can be applied slowly when pushing out the work 48, and a small torque can be applied quickly when returning to the original position. Further, it is also possible to operate with a constant torque by utilizing the characteristic of FIG.

FIG. 8 shows a clamper using a torque control device. The arm 50 is attached to the output shaft 33 of the differential actuator 4.
And a clamp member 52 that clamps the work 51 is pivotally supported at the end of the arm 50, and the clamping force of the clamp member 52 with respect to the work 51 can be controlled to be constant or arbitrary by the above torque control.

〔The invention's effect〕

As described above, according to the present invention, the two induction machines that form the differential actuator together with the differential mechanism are individually controlled by the inverters, so that the output shaft from the zero speed to the normal rotation speed range can be controlled. The effect is that the range of torque control can be expanded, and stable torque can be obtained easily at any time.

[Brief description of drawings]

FIG. 1 is a block connection diagram for explaining a torque control device for a differential actuator according to an embodiment of the present invention,
2 is a sectional view of the differential actuator, FIG. 3 is a torque-rotational speed characteristic diagram of the differential actuator, and FIG. 4 is the same torque-rotational speed when the set frequency of the inverter is changed. FIG. 5 is a characteristic diagram, FIG. 5 is a torque-rotation number characteristic diagram when a load is similarly applied to the output shaft, FIG. 6 is a front view of a gripper using a torque control device, and FIG. 7 is a front view of the work extrusion device. , FIG. 8 is a front view of the clamper, FIG. 9 is a control circuit diagram of a conventional induction machine inverter, and FIG. 10 is a voltage / frequency characteristic diagram of the inverter.
FIG. 11 is a torque-rotational speed characteristic diagram of a conventional induction machine. Reference numerals 1 and 2 are induction machines, 3 is a differential mechanism, 4 is a differential actuator, and 8 and 9 are inverters. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshihiko Yanagiuchi 5-1-1 Yataminami, Higashi-ku, Nagoya-shi, Aichi Mitsubishi Electric Corporation Nagoya Works (72) Inventor Kuniharu Miura 5 Yata-minami, Higashi-ku, Nagoya-shi, Aichi 1-14 No. Mitsubishi Electric Co., Ltd. Nagoya Works (56) Bibliography Showa 59-30699 (JP, U) Showa 57-197750 (JP, U)

Claims (1)

[Claims] 1. A two-induction machine, a differential mechanism for extracting the sum or difference of the rotational speeds of these induction machines and transmitting the sum to the output shaft, and a voltage / frequency output characteristic. By outputting a constant frequency signal to one induction machine and a variable frequency signal to the other induction machine, the torque obtained with respect to the rotation speed of the output shaft is constant for each variable frequency signal. A torque control device for a differential actuator including two inverters for controlling.