JP2001116004A - Hydraulic control device, and control device for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic control device which is favorable from the viewpoints of energy saving and measures to power failure. SOLUTION: Hydraulic fluid in an oil tank 1 is supplied by a hydraulic pump 2 to a servo valve 3. The servo valve 3 changes a supply direction and a supply quantity of the hydraulic fluid in accordance with a command of a servo amplifier to supply the hydraulic fluid to a hydraulic cylinder 4, and return oil from the hydraulic cylinder 4 is returned to the hydraulic tank 1. Excessive hydraulic fluid left unsupplied to the servo valve 3 is returned through a relief valve 5 to the hydraulic tank 1. To a motor control circuit 9, a three- phase 200 V power source and a single-phase 100 V power source are connected, and the three-phase 200 V power source is normally used, while the single-phase 100 V power source is selected and used at the time of power failure of the other power source. Output of a servo control device 14 to operate the servo valve 3 is supplied to the servo valve 3, and it is also supplied to an inverter 13 simultaneously, thereby a rotation number of the hydraulic pump 2 is changed in accordance with the opening of the servo valve 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device represented by a hydraulic servo device and a control circuit of a motor used directly therefor.

[0002]

2. Description of the Related Art FIG. 3 shows a schematic diagram of a typical conventional hydraulic servo system. The hydraulic oil in the oil tank 1 is supplied to a servo valve 3 by a hydraulic pump 2. The servo valve 3 changes the supply direction and supply amount of hydraulic oil according to a command from a servo amplifier (not shown), supplies hydraulic oil to the hydraulic cylinder 4, and returns the return oil from the hydraulic cylinder 4 to the hydraulic tank 1. The surplus hydraulic oil not supplied to the servo valve 3 is
The oil is returned to the oil tank 1 via the relief valve 5.

An accumulator 6 is provided to supply the fluctuation of the pressure of the hydraulic pump 2 and to secure an amount of oil sufficient to operate the hydraulic cylinder 4 to the safe side when the hydraulic pump stops. . The hydraulic pump 2 is driven by a constant-speed electric motor 7. In oil tank 1,
A cooling pipe 8 for cooling the hydraulic oil is provided, and cooling water is supplied.

[0004]

However, such a conventional hydraulic control apparatus has the following problems. The first
Means that the hydraulic pump 2 is rotating even when the cylinder 4 is stopped and supply of hydraulic oil is not necessary, and the electric motor 7 for driving the hydraulic pump 2 consumes electric power. This is not only undesirable from the viewpoint of energy saving, but also causes the hydraulic oil itself to generate heat and the heat of the electric motor 7 to be transmitted to the hydraulic oil via the hydraulic pump 2 to wastefully raise the temperature of the hydraulic oil. The need for extra cooling water is also a problem from the viewpoint of energy saving.

Second, when the power supply of the motor 7 is stopped, not only cannot the operation be continued, but also a large-capacity accumulator 6 is required in some cases as described above. Is to happen.

The present invention has been made in view of such circumstances, and provides a hydraulic control device which is preferable from the viewpoint of energy saving and measures against power failure, and a control circuit of a motor which is directly used and preferably used therefor. As an issue.

[0007]

A first means for solving the above-mentioned problems is that a hydraulic pump is driven by a variable speed motor, and the rotation speed of the variable speed motor corresponds to the opening of the hydraulic control valve. A hydraulic control device (claim 1) characterized in that it is adapted to change.

In this means, the rotational speed of the variable speed motor changes in accordance with the opening of the hydraulic control valve. This can be realized, for example, by changing the rotation speed of the variable speed motor according to the output of the servo amplifier. The rotation speed of the variable speed motor may be substantially proportional to the opening of the servo valve, or the rotation speed may be gradually reduced as the opening of the servo valve decreases. When the servo valve is closed, the rotation may be stopped or the rotation may be performed at a low speed. These can be arbitrarily selected according to the response and the like required for the hydraulic control circuit.

In this means, the amount of excess hydraulic oil circulating through the relief valve is reduced, so that the amount of electric power for driving the motor can be reduced by that amount, and energy can be saved. Also, the relief valve can be made smaller. Further, since the temperature rise of the hydraulic oil is also reduced, the amount of cooling water can be reduced, and in some cases, the cooling water can be eliminated.

[0010] A second means for solving the above-mentioned problems is as follows.
The first means, wherein the control circuit of the variable speed motor rectifies an AC power supply to generate a DC power supply, generates a pulse current or a pseudo AC current from the DC power supply, and supplies the current to the variable speed motor. And at least one of the AC power supplies supplied to the control circuit includes a plurality of power supplies having different specifications from other power supplies, and the control device selects one of the power supplies according to the status of each power supply. (Claim 2).

The pseudo AC means an AC formed by a known voltage type inverter, a PWM type inverter or the like and having a waveform substantially regarded as an AC when viewed from a motor. It is well known that an AC power supply is once converted to DC and converted to a pseudo AC having a desired frequency to perform vector control of an induction motor, or to control DC motor by converting DC into pulse current by PWM control. Matters. The present means covers all such systems.

In this means, a plurality of power supplies having at least one of different specifications from other power supplies are used as the AC power supply to be used. In this specification, "the specifications are different" of the power supply means that at least one of a voltage, a frequency, and the number of phases is different. Power supplies with different specifications have a very low possibility of simultaneous power outage compared to power supplies with the same specification. Therefore, by inputting a plurality of power supplies having different specifications and selecting and using a sound power source among them, the possibility that the hydraulic pump actually stops can be almost eliminated. Therefore, the accumulator may have a small capacity enough to absorb the pulsation of the hydraulic pump, and the accumulator may be omitted in some cases.

A third means for solving the above-mentioned problem is as follows.
In the second means, when the supply of all AC power is stopped to the DC power supply, the target to be hydraulically controlled,
The battery is connected to a battery having a capacity capable of driving the hydraulic pump only for a time required for driving to the safe side (claim 3).

Although the second means can cope with most power failures, in rare cases, power supplies with different specifications may fail simultaneously. If there is a danger to the equipment if the actuator stops during a power outage, it is necessary to stop the actuator after driving it to a safe side. In order to cope with such a case, the present means has a battery having a capacity capable of driving the hydraulic pump for a time necessary to drive the target to be hydraulically controlled to the safe side. When all of the AC power is stopped, power is supplied from this battery to drive the hydraulic pump and drive the actuator. Therefore, the equipment can be kept safe even without a large-capacity accumulator.

[0015] A fourth means for solving the above problems is as follows.
A control circuit for controlling the number of revolutions of the motor, wherein the AC power supply is rectified into a DC power supply, and a pulse current or a pseudo AC current is created from the DC power supply and supplied to the variable speed motor. The AC power supplied to the control circuit includes at least one of a plurality of power supplies having different specifications from other power supplies.
An electric motor control circuit is characterized in that one of them is selected and used.

In this means, at least one of the AC power supplies is composed of a plurality of power supplies having specifications different from those of the other power supplies. It is possible to drive the variable speed electric motor substantially uninterruptedly without any power.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, 1 is an oil tank, 2
Is a hydraulic pump, 3 is a servo valve, 4 is a hydraulic cylinder, 5
Is a relief valve, 7 is a motor, 8 is a cooling pipe, 9 is a motor control circuit, 10 and 11 are rectifiers, 12 is a storage battery, 13 is an inverter, and 14 is a servo control circuit.

The hydraulic oil in the oil tank 1 is supplied to a servo valve 3 by a hydraulic pump 2. The servo valve 3 changes the supply direction and supply amount of hydraulic oil according to a command of a servo amplifier (not shown), and supplies hydraulic oil to the hydraulic cylinder 4.
The return oil from the hydraulic cylinder 4 is returned to the hydraulic tank 1.
Excess hydraulic oil not supplied to the servo valve 3 is returned to the oil tank 1 via the relief valve 5.

The hydraulic pump 2 is driven by a variable speed electric motor 7. The oil tank 1 is provided with a cooling pipe 8 for cooling hydraulic oil, and is supplied with cooling water.
The rotation speed of the motor 7 is controlled by the motor control circuit 9 and is variable. In this embodiment, a three-phase induction motor is used as the motor 7, and the motor control circuit 9 controls the number of rotations by controlling the frequency of the power supplied to the motor 7.

The main part of the motor control circuit 9 is a well-known one, so a detailed description thereof will be omitted. However, the AC power supply is converted to DC by a rectifier, and then a pseudo AC is applied by PWM control or voltage control. The rotation speed of the electric motor 7 is made variable by changing the frequency of the alternating current.

In the present embodiment, a three-phase 200 V power source and a single-phase 100 V power source are supplied to the motor control circuit 9.
It is designed to be converted to direct current of the same voltage. Normally, a three-phase 200V power supply is selected and used, but when this power supply fails, a single-phase 100V power supply is selected and used.

Servo controller 14 for operating servo valve 3
Is supplied to the servo valve 3 and also to the inverter 13 to change the frequency of the output of the inverter 13. As a result, the frequency of the output of the inverter 13 is switched in multiple stages corresponding to the opening of the servo valve 3. When the opening of the servo valve 3 is large, the frequency is high, and when the opening of the servo valve 3 is small, Has a lower frequency.

In a hydraulic control system in which the response delay of the rotation speed of the motor 7 does not matter, the motor 7 may be stopped when the opening of the servo valve 3 is zero. In a hydraulic control system that requires a faster response than the response, the rotational speed of the electric motor 7 is set so that the hydraulic oil always flows at a higher flow rate than the hydraulic oil required by the servo valve 3. A part of the hydraulic oil is returned to the oil tank 1 via the relief valve 5. In any case, unlike the related art, the hydraulic pump 2 does not always send a constant amount of hydraulic oil, which saves energy and reduces the temperature rise of the hydraulic oil. And cooling water may not be required in some cases.

In this embodiment, when the three-phase 200V power supply is interrupted, power is immediately supplied from the single-phase 100V power supply, so that the operation can be performed without stopping the rotation of the motor 7. For this reason, the accumulator, which is required in the prior art, is omitted.

The three-phase 200V power supply and the single-phase 100V power supply
In many cases, the branch is near the source of the power supply,
It is extremely rare that a power failure occurs at the same time due to an accident on the way. By making such a connection, uninterrupted operation is possible in most cases without using special security power or the like.

However, in the present embodiment,
In the event of a simultaneous power outage of both power supplies, in such a case, there is a storage battery 12 having sufficient power supply capacity to supply the hydraulic pressure necessary to drive the hydraulic cylinder 4 to the safe side of the installation. ing. The storage battery 12 is charged in a steady state, and supplies the charged current to the inverter 13 when the power supply from the rectifiers 10 and 11 is cut off due to the power failure of both power supplies. The control related to this and the operation of the servo control device 14 when both power supplies are cut off are obvious matters to those skilled in the art, and thus the description thereof will be omitted. It should be noted that the servo control device 14 also has a function of switching to another power supply when one power supply fails, and a battery capable of continuing operation when both power supplies fail. There is no. In addition, when both power supplies lose power, if the hydraulic cylinder 4 may be locked at that position, the storage battery 12 can be omitted.

As the storage battery, a lithium ion battery or the like can be used, and an electric double layer capacitor or the like can also be used (in the present specification, such a battery is also regarded as a kind of battery). Further, a primary battery may be used instead of the storage battery.

FIG. 2 is an example of the embodiment of the present invention, and is a diagram showing an example of a circuit configuration of the motor control circuit 9. As shown in FIG.
After being rectified by the rectifier D 1, the three-phase 200 V power, which is the main power supply, is smoothed by the capacitor C 1, charges the storage battery 12 via the backflow prevention diode D 2, and is supplied to the inverter 13. The inverter 13 is controlled by the servo controller 14 as described above, generates a pseudo AC having a designated frequency, and supplies the pseudo AC to the induction motor.

The single-phase 100V power supply as a sub-power supply is boosted by a transformer T so that the voltage after rectification becomes the same as the voltage obtained by rectifying the three-phase 200V power supply, and then rectified by a rectifier D3 to obtain a capacitor C2. Is smoothed. Three
When the phase 200V power supply is normal, the relay X is turned on by the rectified voltage and the b contact x is open, so that this voltage is not supplied to the storage battery 12 or the inverter 13.

When the three-phase 200V power supply fails, the relay X
Is turned off, the contact x is closed, and the single-phase 100
The rectified power of the V power supply charges the storage battery 12 via the backflow prevention diode D4 and is supplied to the inverter 13.

In the above embodiment, a three-phase induction motor is used as the electric motor. However, a synchronous motor may be used.
Alternatively, a DC current control device based on PWM control may be used.

[0032]

As described above, according to the first aspect of the present invention, the amount of electric power for driving the motor can be reduced, energy can be saved, and the relief valve is also reduced. be able to.

In the invention according to claim 2, the possibility that the hydraulic pump actually stops can be almost eliminated. In the invention according to claim 3, the equipment can be kept safe even without a large-capacity accumulator. In the invention according to claim 4, the variable speed electric motor can be driven substantially without any power failure.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a hydraulic control device which is an example of an embodiment of the present invention.

FIG. 2 is an example of an embodiment of the present invention, and is a diagram illustrating an example of a circuit configuration of a motor control circuit.

FIG. 3 is a diagram showing an outline of a conventional typical hydraulic servo system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Oil tank 2 ... Hydraulic pump 3 ... Servo valve 4 ... Hydraulic cylinder 5 ... Relief valve 7 ... Electric motor 8 ... Cooling piping 9 ... Electric motor control circuit 10, 11 ... Rectifier 12 ... Storage battery 13 ... Inverter 14 ... Servo control circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshinobu Taguchi 2951-4 Ishikawacho, Hachioji-shi, Tokyo Inside Nireco Co., Ltd. (72) Inventor Masayuki Fukuda 2951-4 Ishikawacho, Hachioji-shi, Tokyo Nireko Co., Ltd. (72) Inventor Yukio Imai 2951, Ishikawa-cho, Hachioji-shi, Tokyo F-term in Nireco Co., Ltd. 3H089 BB01 CC01 DA02 DA14 DA17 DB03 DB46 DB49 DB54 EE18 EE31 FF05 FF12 GG02

Claims (4)

[Claims] 1. A hydraulic control device, wherein a hydraulic pump is driven by a variable speed motor, and a rotation speed of the variable speed motor changes according to an opening of a hydraulic control valve. 2. The hydraulic control device according to claim 1, wherein the control circuit of the variable speed motor rectifies an AC power supply to be a DC power supply, and generates a pulse current or a pseudo AC current from the DC power supply. The AC power supplied to the control circuit includes at least one of a plurality of power supplies having different specifications from other power supplies. A hydraulic control device characterized in that one of them is selected and used in response to the request. 3. The hydraulic control device according to claim 2, wherein when the supply of all AC power to the DC power supply is stopped, the DC power supply is required to drive a hydraulically controlled object to a safe side. A hydraulic control device, characterized in that a battery having a capacity capable of driving the hydraulic pump for a short time is connected. 4. A control circuit for controlling the number of revolutions of an electric motor, comprising: rectifying an AC power supply into a DC power supply; generating a pulse current or a pseudo AC current from the DC power supply; And at least one of the AC power supplies supplied to the control circuit includes a plurality of power supplies having different specifications from other power supplies, and the control device selects one of the power supplies according to the status of each power supply A control circuit for an electric motor, wherein the control circuit is used as a motor.