JP2001317447A - Hydraulic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably operate a hydrostatic transformer even at micro-output time. SOLUTION: An output shaft of an electric motor is fastened to a common shaft of a hydraulic pump and a hydraulic motor. Driving force of the hydraulic pump is shared by the hydraulic motor and the electric motor, and a very small quantity is allocated first to the electric motor. Thus, the electric motor is integrally added to the hydrostatic transformer via the common shaft, and control for giving preference to driving by an operationally easily stabilizing electric motor is performed at micro-output time so that the hydrostatic transformer is stably operated even at micro-output time without making a sacrifice such as for change-over to an auxiliary pump and an increase in consumption energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device called a hydrotransformer or a hydraulic device incorporating the same, and more particularly, to an improvement in operating characteristics thereof. The hydrotransformer is a combination of a hydraulic pump and a hydraulic motor with a common rotating shaft, and the hydraulic pump can be driven to rotate by supplying a pressure liquid to the hydraulic motor. . Normally, a hydraulic pump and a hydraulic motor are incorporated in a body (base) formed by processing a single block or assembling a plurality of blocks.
A positive displacement pump is used for both the hydraulic pump and the hydraulic motor. In many cases, a variable displacement motor is used for a hydraulic motor or the like. In such a case, the capacity is variably controlled by an appropriate control device, so that automatic control and follow-up control of the discharge flow rate of the hydraulic pump and the like can be performed.

[0002]

2. Description of the Related Art When a hydrotransformer is used as a hydraulic pressure source such as a hydraulic pressure source, the regeneration of braking energy and the smoothing of power can be achieved relatively easily. In addition, it is also used in injection molding machines and the like (Japanese Unexamined Patent Publication No.
199999). In the injection molding machine 70 (FIG. 6)
(A)), the pressure liquid discharged from the hydraulic pressure source 71 is:
The mold clamping device 42, the ejection device 43, the injection device 44,
It is supplied to a weighing device 45, a nozzle moving device 46, and the like, and is properly used at a plurality of locations. The flow rate Q to be supplied is different depending on the operation state and the like in each of the devices 42 to 46 or even the same device. The flow rate Q follows the flow rate control command Qc by automatic control / following control by combining the device 72.

[0003] The hydraulic pressure source 71 is used to store a pressure liquid to be sent to the hydraulic motor 12 through the liquid flow path 26 in addition to a hydrotransformer in which the hydraulic pump 11 and the hydraulic motor 12 are connected. The pressure accumulator 25 provided together with the check valve 24 and the pressure accumulator 25
There is also provided a small pump 23 driven by a small electric motor 22 to send the pressurized liquid to the pump. The hydraulic motor 12 is provided with a variable displacement mechanism 17 and an electromagnetic proportional control valve 16 so that the flow rate can be controlled by the variable control of the displacement of the hydraulic motor 12. Further, the capacity variable mechanism 17 is provided with a capacity detecting means 18 so that the control device 72 can perform the control by the feedback control.
The rotational speed detecting means 19 is attached to each of them, and the detection signals Cf and Rf are fed back to the control device 72. The controller 72 detects the flow rate Q based on the detection value Rf, generates a proportional control current C based on the value and the flow rate control command Qc, and sends the proportional control current C to the electromagnetic proportional control valve 16, Control is performed so that the flow rate Q follows the flow rate control command Qc.

Further, in application to an injection molding machine or the like, extremely slow feeding or the like is performed as compared with a high-speed reciprocating operation. However, at such a low speed driving, the flow rate Q becomes very small, and stick-slip appears. In order to prevent this (see FIG. 6A), an auxiliary pump 75 is also provided in parallel with the hydraulic pressure source 71, and is driven by a servo motor 74 and a motor driver 73. ing.
At the time of low-speed drive / low-speed control, the auxiliary pump 75
The switching valve 76 interposed and connected to the discharge line is opened to utilize the flow control by the auxiliary pump 75, otherwise, the switching valve 76 is closed to utilize the flow control by the hydraulic pressure source 71 and the control device 72. It has become.

[0005]

In order to switch between the hydrotransformer and the auxiliary pump in this way, it is necessary to determine the switching timing of the switching valve 76 and the like. For this reason, the applicable range of the conventional hydrotransformer and the hydraulic device incorporating the same are limited. Further, even if the switching timing can be determined, it is difficult to apply to applications in which switching cannot be performed smoothly.

On the other hand, it is conceivable that a part of the discharge flow rate of the hydrotransformer is always bleed-off so that the discharge flow rate is not so small as to cause stick-slip. However, in that case, switching to the auxiliary pump would not be necessary, but at the expense of increased energy loss.

Therefore, in order to expand the range of application without paying such a price, it is a technical problem how to improve related devices such as a hydrotransformer itself and a control device used in combination therewith. The present invention
It was made to solve such a problem,
It is an object of the present invention to stably operate a hydrotransformer even at a minute output.

[0008]

Means for Solving the Problems First and second solving means invented to solve such problems are as follows.
The configuration and operation and effect will be described below.

[First Solution] A hydraulic device according to a first solution is a hydraulic motor which shares a rotary shaft with a rotary hydraulic pump as described in claim 1 at the time of filing. And a hydraulic device having an electric motor, the output shaft of which is connected to the rotating shaft. Here, the above-mentioned "tightness" means a coupling state in which there is no play in the rotation transmission between the output shaft and the rotation shaft.

In the hydraulic device according to the first solution, the hydraulic pump and the hydraulic motor share a rotating shaft, so that a hydrotransformer is formed by the hydraulic pump and the hydraulic motor. By supplying the pressurized liquid to the motor, the hydraulic pump is driven to rotate. Since the output shaft of the electric motor is also connected to the rotating shaft, the hydraulic pump is also driven to rotate by supplying a drive current to the electric motor. In addition, the rotational drive of the hydraulic pump by the electric motor is not affected by the compressibility of the liquid and the smoothing of the pressure by the accumulator as in the rotational drive of the hydraulic pump by the hydraulic motor. Since the connection with the output shaft is made firm, it is stable even when the pump discharge flow rate is extremely small or when only a small drive torque is output.

As described above, since the electric motor is integrally added to the hydrotransformer via the shared shaft and the common shaft, the rotation of the hydraulic pump is driven by the combined force of the outputs of the hydraulic motor and the electric motor. Therefore, it is not necessary to separately supply a small flow rate by arranging auxiliary pumps and switching valves,
It is not necessary to bleed off and make the hydrotransformer discharge a certain amount or more, and it is possible to freely combine the drive with the hydraulic motor and the drive with the electric motor, for example, stable operation at minute output The priority is given to the driving by the electric motor which is easy to perform, and it is possible to easily use the driving by the hydraulic pump suitable for the large output. Therefore, according to the present invention, it is possible to realize a hydrotransformer that can operate stably even at a minute output without sacrificing switching to an auxiliary pump or increasing energy consumption.

[Second Solution] A hydraulic device according to a second solution is provided by the first device described above.
A hydraulic device according to the invention, wherein a control device is provided, and the control device causes the driving force of the hydraulic pump to be shared between the hydraulic motor and the electric motor,
At that time, a minute part of the driving force is allocated to the electric motor first.

In the hydraulic device according to the second solution, the hydraulic motor and the electric motor share the driving force of the hydraulic pump in accordance with the control of the control device. When the driving force becomes very small, a process of allocating to the electric motor first is performed. As a result, at the time of minute output, driving by the electric motor which is easy to stabilize the operation is performed with priority. Therefore, according to the present invention, the hydrotransformer can operate stably even at a minute output without sacrificing switching to the auxiliary pump or saving energy consumption.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several embodiments for implementing the hydraulic apparatus of the present invention achieved by such a solution will be described.

According to a first embodiment of the present invention, a rotary hydraulic pump capable of operating a motor, a hydraulic motor capable of operating a pump, and the hydraulic It comprises a rotary shaft shared by a pump and the hydraulic motor, and an electric motor having an output shaft connected to the rotary shaft. In this case, reverse flow and reverse rotation are also possible, so that the ability of energy regeneration is high.

A second embodiment of the present invention is a hydraulic device according to the above-mentioned solution and embodiment, as described in claim 4 at the beginning of the application, wherein any one of the hydraulic pump and the hydraulic motor is provided. A capacity variable mechanism capable of changing the discharge / suction amount per unit rotation is added to one or both of them. In this case, the variable range of the discharge flow rate is widened, and quick variable control can be easily performed by controlling the capacity variable mechanism.

A third embodiment of the present invention is a hydraulic device according to the above-described embodiment, wherein the motor control means controls the rotation of the electric motor. Capacity control means for controlling the capacity variable mechanism, calculation means for calculating a control amount for following based on a received or generated control command, and the control amount for the motor control means and the capacity control means Distribution means for distributing. This makes it possible to easily and reliably realize the function of “sharing” in the control device of the second solving means described above.

A fourth embodiment of the present invention is the hydraulic apparatus according to the above-mentioned embodiment, as described in claim 6 at the beginning of the application, wherein the calculating means makes the control amount proportional to torque or substantially proportional thereto. The calculation is based on the torque equivalent amount, and when the control amount is weaker than a predetermined value, the distribution means allocates the entire amount of the control amount to the motor control means. As a result, the second
The function of “assigning a minute amount” in the control device of the solving means can be reliably realized.

A fifth embodiment of the present invention is directed to a hydraulic apparatus according to the above-described embodiment as described in claim 7 at the outset of the application, wherein the output torque of the electric motor or a corresponding one-to-one output torque of the electric motor is provided. Torque detection means for detecting the amount is provided,
When the torque is smaller than a predetermined value, the distribution means allocates the entire control amount to the motor control means. As a result, the function of “allocating a minute amount” in the control device of the second solving means is reliably realized, and the requirement of limiting the dimension of the control amount to torque or the like is released. Can be easily realized.

[0020] A sixth embodiment of the present invention is the hydraulic apparatus according to the above-described embodiment, wherein the predetermined value is larger than the static friction torque of the rotating shaft. That is, it is set to be smaller than the maximum value of the output torque of the electric motor. In this case, stick slip is surely eliminated.

A seventh embodiment of the present invention is the hydraulic apparatus according to the above-described embodiment, as described in claims 9 and 10 at the beginning of the application, wherein the hydraulic pump has a smaller capacity than the hydraulic pump. And a pressure accumulator connected to a liquid flow path capable of supplying pressure liquid from the small capacity hydraulic pump to the hydraulic motor. As a result, the power is smoothed, so that the size of the power receiving equipment is reduced.

With respect to the hydraulic apparatus of the present invention achieved by the above-described solution and embodiments, specific embodiments for implementing the hydraulic apparatus will be described with reference to the following first to fourth embodiments. The first embodiment shown in FIG. 1 and FIG.
A second solution and the first to fourth, sixth, and seventh embodiments are embodied. Further, the second embodiment shown in FIG. 3, the third embodiment of FIG. 4, and the fourth embodiment of FIG. 5 are modifications of the first embodiment. In addition, in showing them,
For simplicity, etc., symbolic diagrams and block diagrams are frequently used, the hydraulic main line is shown by a thin solid line, the hydraulic pilot line is shown by a thin long broken line, and the electric signal line is shown by a thin dashed line.

[0023]

First Embodiment A first embodiment of a hydraulic device according to the present invention will be described with reference to the drawings. FIG. 1A is a partial longitudinal sectional view of a hydrotransformer with a servomotor, FIG. 1B is a circuit diagram of a hydraulic pressure source and the like incorporating the hydrotransformer, and FIG. FIG. 2 is a block diagram of a transformer control device, and FIG.
(B) is a circuit diagram of an injection molding machine as a typical application example.

The hydrotransformer 10, which is a main part of the hydraulic apparatus (see FIG. 1A), is obtained by adding an electric motor 13 such as an AC servomotor to a general hydrotransformer. That is, in addition to the rotary hydraulic pump 11, a hydraulic motor 12 is also incorporated into a body made of cast iron or the like, and one long or several rigidly connected long shafts 14 are provided. Hydraulic pump 1
The first motor 1 and the hydraulic motor 12 are rotatably supported so as to extend through both centers thereof. Since the rotating shaft 14 is shared by the hydraulic pump 11 and the hydraulic motor 12, the two shafts 11 and 12 rotate together. Further, one end of the rotating shaft 14 is connected to a tip of the output shaft 15 protruding from the electric motor 13. The connection is made firmly by fitting with press fitting or appropriate fastening. With such an integral connection, the output shaft 15 and the rotating shaft 14 rotate together.

As the hydraulic pump 11 and the hydraulic motor 12, an axial piston pump or an axial piston motor as shown in the figure is often used, but a radial piston type or a vane type may also be used. Such a positive displacement pump or motor usually operates as a pump when driving a rotating shaft, and operates as a motor when a pressurized liquid is fed. Therefore, the hydraulic pump 11 is a rotary pump capable of motor operation. The hydraulic motor 12 is also a motor that can also perform a pump operation. The hydraulic motor 12 is of a variable displacement type, and a variable displacement mechanism 17 is incorporated in the body together with the hydraulic motor 12 in order to change the discharge / suction amount per unit rotation. , An electromagnetic proportional control valve 16 for operating it at pilot pressure. The electromagnetic proportional control valve 16 is not limited to an open control valve, but may be a servo valve. Variable capacity mechanism 1
7, the capacity of the hydraulic motor 12 is varied by changing the tilt angle of the swash plate in the illustrated example. Hydraulic motor 1 according to proportional control current C
It suffices if the capacity of 2 is made variable.

In the hydraulic pressure source 20 incorporating the hydrotransformer 10 (see FIG. 1 (b)), a small-sized electric motor 22 is used to sufficiently prepare a pressure liquid to be used for driving the hydraulic motor 12. In addition to the driven small pump 23, an accumulator 25 capable of storing a large amount of liquid at a substantially constant pressure is also provided. The pressure accumulator 25 is connected to a liquid flow path 26 extending from the discharge port of the small pump 23 and reaching the suction port of the hydraulic motor 12. The liquid flow path 26 is secured by a suitable metal pipe, a drilled hole in a metal block, or the like, and a check valve 24 for preventing a reverse flow to the small pump 23 is also interposed therebetween. The hydraulic pump 11 has a capacity sufficient to cope with the peak of the required flow rate Q, whereas the small pump 23 has an average value of the flow rate Q and the hydraulic motor 12 and the hydraulic pressure. A hydraulic pump having a smaller capacity than the hydraulic pump 11 is adopted in consideration of an average flow ratio with the pump 11 and the like. Then, a substantially constant pressure liquid is continuously sent from the tank 21 to the pressure accumulator 25 and stored therein, so that a required amount of the pressure liquid can be supplied to the hydraulic motor 12 at any time.

In order to control the discharge flow rate Q of the hydraulic pressure source 20, the hydrotransformer 10 is connected to the hydrotransformer 10 (see FIG. 1B) via an appropriate signal cable or the like provided with an electromagnetic shield or the like. , Control device 30 is connected. The control device 30 is composed of an analog or digital electronic circuit, includes a signal input / output interface circuit, and the like, receives a flow control command Qc from a higher-level controller, a setting device, or the like, and inputs the command value. At the same time, the flow rate Q is detected, and a proportional control current C is generated so that the flow rate Q follows the flow rate control command Qc and is sent to the electromagnetic proportional control valve 16. At this time, the detection of the flow rate Q may be performed directly using a flow meter or the like, but by measuring the tilt angle of the swash plate or the like so that it can be performed more simply, more accurately and indirectly. A capacity detecting means 18 for detecting the capacity of the hydraulic motor 12 by the capacity variable mechanism 17 is provided. The detected capacity Cf is sent to the control device 30 and the output shaft 15 of the electric motor 13 is output.
Alternatively, a rotation speed detecting means 19 comprising an encoder or the like linked to the rotation shaft 14 such as the hydraulic motor 12 is also provided, and the rotation speed Rf detected by the rotation speed detection means 19 is also sent to the control device 30 as a signal. Further, in order to drive the electric motor 13 as a servomotor capable of controlling the torque, the motor drive current I supplied from the control device 30 to the electric motor 13 is controlled.
Is also provided. Since the output torque of the electric motor 13 is determined according to the motor drive current I, the drive current detection member 39 can be said to be an indirect torque detection means, and the motor torque If detected by the drive current detection member 39 is also used by the control device 30. I have.

The control device 30 (see FIG. 2A) supplies a flow rate Q based on a flow control command Qc received from the outside.
The flow control unit 31 includes a flow rate detection unit 31 that calculates a detected flow rate Qf of an estimated value of the flow rate Q based on the rotation speed Rf, and a subtraction circuit, etc. A difference calculation unit 32 for calculating a flow error ΔQ between Qc and the detected flow Qf, and a flow control calculation unit for performing an appropriate calculation based on a PI control method or the like from the flow error ΔQ to calculate the total control amount Tc in the torque dimension. 33 are provided. Further, the control device 30 receives a motor control amount Ic as a control command as a motor control means for performing feedback control of the rotation of the electric motor 13 and receives the motor torque I
A motor control unit 37 that generates a current command that causes f to follow f, and a motor drive unit 38 that includes, for example, an inverter that generates a motor drive current I according to the current command and sends it to the electric motor 13 are provided. Further, as capacity control means for performing feedback control of the capacity variable mechanism 17 via the electromagnetic proportional control valve 16, capacity control for receiving a capacity control amount Cc as a control command and generating a current command to make the detected capacity Cf follow the control command. An electromagnetic drive unit 36, for example, a push-pull power amplifier that generates a proportional control current C according to the current command and sends the generated proportional control current C to the electromagnetic proportional control valve 16 is provided.

The control device 30 includes a total control amount Tc as distribution means for distributing the total control amount Tc to the motor control unit 37 of the motor control means and the capacity control unit 35 of the capacity control means.
A control amount distributing unit 34 for generating a motor control amount Ic and a displacement control amount Cc from the control unit is also provided. Control amount distribution unit 34
Is a predetermined value A fixedly set in advance or re-settable
When the total control amount Tc is weaker than the predetermined value A as a torque, that is, when the absolute value is smaller, the motor control amount Ic is assigned to allocate the entire control amount Tc to the motor control means.
c. Specifically, in order to easily perform the process, the motor control amount Ic is calculated by setting the upper limit of the total control amount Tc to + A and setting the lower limit to −A to be within a predetermined range, and calculating the total control amount Tc by − A
The capacity control amount Cc is calculated by extracting the portion from + A to the dead zone. At this time, an accompanying process accompanying unit conversion from the total control amount Tc expressed in the dimension of torque to the capacity control amount Cc expressed in the dimension of capacity is also performed. Further, the motor control amount Ic and the capacity control amount Cc obtained by decomposing the total control amount Tc are distributed to the motor control unit 37 and the capacity control unit 35 as control commands to the respective minor feedback loops. It is supposed to be.

The predetermined value A is the value of the hydrotransformer 1
In order to prevent the occurrence of the stick-slip phenomenon at 0, the static friction torque of the rotating shaft 14 is made larger. Further, if the motor control amount Ic exceeds the controllable range of the electric motor 13, the control becomes impossible, so that the predetermined value A
Is smaller than the maximum value of the output torque of the electric motor 13,
It is usually set below the rated output torque. For this purpose, the electric motor 13 whose output torque exceeds the static friction torque of the rotating shaft 14 is also used.
Although the static friction torque of the rotating shaft 14 varies depending on the material of the member and the use condition, it is not constant, but is often about several percent of the maximum output torque of the hydrotransformer 10. On the other hand, an electric motor having a large output torque generally has poor response. In consideration of these conditions, a small servomotor whose output torque is about 20% of the maximum output torque of the hydrotransformer 10 is usually adopted as the electric motor 13.

In the injection molding machine 40 incorporating such a control device 30 and the hydraulic pressure source 20 (see FIG. 2B), a mold clamping device 42, an ejection device 43, an injection device 44, a measuring device 45, a nozzle Moving device 46, etc.
The main controller 41, which is composed of a sequencer or the like, for example, performs sequence control with respect to the control devices 3 to 46 when issuing appropriate commands to the devices 42 to 46.
0, a flow control command Qc is issued. At this time, a motor driver 73 not provided in the injection molding machine 40 is used.
There is no need to generate a command to the switching valve 76, and it is not necessary to send the command at an appropriate timing.

The usage and operation of the hydraulic device of the first embodiment will be described.

When the pressurized liquid is stored in the pressure accumulator 25 by the small pump 23, the main controller 41 moves in the direction from the main controller 41 to the mold clamping devices 42 to 46 in accordance with a predetermined procedure corresponding to the injection molding process (see Japanese Patent Application Laid-Open No. 11-19997). When a flow control command Qc is transmitted from the main controller 41 to the control device 30 while a control valve switching command or the like is transmitted, the rotation speed Rf of the control device 30 is controlled by the difference calculation unit 32 and the flow control calculation unit 33. , The total control amount Tc is obtained from the motor control amount I by the control amount distribution unit 34.
c and a capacity control amount Cc, which are distributed to a motor control unit 37 and a capacity control unit 35. Then, a motor drive current I is generated by the motor control unit 37 and the motor drive unit 38. Unit 35 and electromagnetic drive unit 36
Generates the proportional control current C.

Driven by the motor drive current I,
The electric motor 13 outputs to the output shaft 15 a motor torque If that follows the motor control amount Ic. At the same time, since the electromagnetic proportional control valve 16 and the variable displacement mechanism 17 change the capacity of the hydraulic motor 12 according to the proportional control current C, the output torque of the hydraulic motor 12 changes accordingly. The power is transmitted to the rotation shaft 14. This rotating shaft 14 has
Since the torque of the output shaft 15 is also transmitted through the binding portion,
The hydraulic pump 11 is rotationally driven with a torque obtained by adding the output torques of the electric motor 13 and the hydraulic motor 12, and sends the pressure liquid having the flow rate Q corresponding to the flow control command Qc to the mold clamping devices 42 to 46. Pay. The pressurized liquid is supplied to a mold clamping device 42 to 4
6.

In this manner, the injection molding machine 40 operates properly. At this time, when the flow rate control command Qc becomes smaller than the predetermined value A when the fine speed control is required, the hydraulic pump 11
Is driven exclusively by the electric motor 13. The small electric motor 13 has excellent responsiveness and does not continue to generate excess torque, so that the load is not rapidly accelerated or decelerated to an excessive degree, so that the occurrence of stick-slip in the hydrotransformer 10 is avoided. The Rukoto. When the flow control command Qc is larger than the predetermined value A, the torque exceeding the predetermined value A
2, the hydraulic pump 11 is driven with a torque obtained by combining the torque and the output torque of the electric motor 13 corresponding to the predetermined value A.

In any case, an appropriate amount of flow Q follows the flow control command Qc from the hydraulic pressure source 20 to the mold clamping device 42-4.
6. As a result, a wide range of flow control from high speed to very low speed can be appropriately performed without impairing the advantages of the hydrotransformer such as power smoothing and energy saving, and the instructions can be given easily. It has become.

[0037]

Second Embodiment A hydraulic apparatus according to the present invention whose flow chart is shown in FIG. 3 is the same as the first embodiment described above, but is embodied in another form. That is, a computer is used as the control device 30, and the calculation means (31 to 33), the distribution means (34), the capacity control means (35), the motor control means (37) and the like are embodied by program processing. I have. A general-purpose microprocessor, a digital signal processor, or the like is used for the computer, and a serial or parallel digital data input / output circuit is built in or externally attached. A / D conversion circuits and D / A conversion circuits are also provided as necessary.

More specifically, the flow rate control command Qc, the detected capacity Cf, the motor torque If, and the rotation speed Rf are converted into digital values and input (step S1). Next, the detected flow rate Qf is calculated from the rotation speed Rf (step S2), and the flow rate control command Qc and the detected flow rate Qf are calculated.
Then, the flow rate error ΔQ is calculated, and the total control amount Tc is also calculated (step S3), and the processing of the calculating means is executed. Then, the displacement control amount Cc and the motor control amount Ic are calculated from the total control amount Tc and the predetermined value A (Step S).
4) The processing of the distribution means is executed.

Thereafter, the value of the proportional control current C is calculated from the capacity control amount Cc and the detected capacity Cf (step S5),
The current is output to the electromagnetic proportional control valve 16 (step S6), and the processing of the capacity control means is executed. Finally, the value of the motor drive current I or the voltage pulse width based on the PWM modulation is calculated from the motor control amount Ic and the motor torque If (step S7), and the current is output to the electric motor 13 (step S8). ), The processing of the motor control means is executed.

In this control device, the series of processes are repeated at a predetermined cycle, and the same operation result as that described for the control device 30 of the first embodiment can be obtained.

[0041]

Third Embodiment The hydraulic device of the present invention whose block diagram is shown in FIG. 4 is different from that of the first embodiment in that the main controller 51 has a pressure control command Pc in addition to the flow control command Qc. And the control device 50 performs pressure control in addition to the flow rate control. Further, a pressure gauge 52 for detecting the discharge pressure is connected to a discharge line or the like of the hydraulic pump 11, and the detected pressure Pf is fed back to the control device 50.

The control device 50 has a subtraction circuit and the like in order to calculate a pressure control amount Tp for causing the pressure Pf to follow the pressure control command Pc in addition to the elements 31 to 38 of the control device 30. Pressure error ΔP between control command Pc and pressure Pf
, A pressure control calculator 54 that performs an appropriate calculation based on the PI control method or the like from the pressure error ΔP to calculate the pressure control amount Tp in the torque dimension as well, and a flow rate error ΔQ and a pressure error. A comparison unit 55 that compares the value with ΔP and outputs a determination S corresponding to the magnitude, a pressure control amount Tp according to the determination S, and a flow control amount Tq from the flow control operation unit 33 (that is, the total amount in the first embodiment) Control amount Tc), and selects this as the total control amount Tc.
4 is also provided.

In this case, in addition to the flow control for causing the flow Q to follow the flow control command Qc, the pressure P
Not only can pressure control to follow f be performed, but switching between the two controls can also be performed automatically. Therefore, for example, when the movable member such as the injection cylinder reaches the operation limit and the operating force / reaction force suddenly increases as in the case of driving the injection device 44, the control content is changed from the flow control (speed control) to the pressure control (power control). This is convenient for applications in which automatic switching to control is desired. It should be noted that even when such automatic switching is required only in a specific scene, it is possible to easily cope with the situation by selectively transmitting the determination S to the selection unit 56 using an AND gate or the like. it can.

[0044]

Fourth Embodiment A hydraulic device 60 of the present invention whose circuit diagram is shown in FIG. 5 is different from that of the first embodiment in that the hydraulic pressure source 62 includes not only the hydraulic motor 12 but also the hydraulic motor 12. The pump 11 is also of the variable displacement type, and the control device 61
Is that the displacement control of the hydraulic pump 11 is performed in addition to the displacement control of the hydraulic motor 12.

As the hydraulic pump 11, an axial piston pump or the like capable of tilting a swash plate is employed as in the case of the hydraulic motor 12, and an electromagnetic proportional control valve 16 for the hydraulic motor 12 is used.
Also, an electromagnetic proportional control valve 63 similar to the variable capacity mechanism 17 and the capacity detection means 18, a variable capacity mechanism 64 and a capacity detection means 65.
Is attached.

Then, by the operation of the control device 61, etc.,
The detected flow rate Qf is calculated from the rotation speed Rf, the detected capacity Cf, and the detected capacity C2f of the capacity detecting means 65, and the total control amount Tc is calculated from the detected flow rate Qf and the flow rate control command Qc. Further, when distributing the total control amount Tc, first, a predetermined value A
A weaker portion is assigned to the motor control amount Ic, and a portion exceeding the motor control amount Ic and falling within the limit of the proportional control current C is assigned to the displacement control amount Cc. Unit 35 and electromagnetic drive unit 36
Proportional control current C2 by another capacity control means similar to
And the proportional control current C2 is sent to the electromagnetic proportional control valve 63.

As described above, since the variable control of the hydraulic pump 11 is also applied to a large flow which cannot be processed only by the variable control of the electric motor 13 and the hydraulic motor 12, the range in which the flow rate can be controlled is widened and the wide range is controlled. Appropriate flow control is performed throughout.

[0048]

[Others] In the above embodiment, application to an injection molding machine has been described. However, application of the present invention is not limited to this.
Various hydraulic systems, for example, a press machine and a die cast machine, as well as a glass forming machine, a machine tool, a press-fitting component mounting device, a transfer device, a robot arm, and the like are possible. Further, as for the liquid, oil pressure is widely used and oil is easy to use, but it is not limited to this.For example, depending on the characteristics and restrictions of the application, water, a chemically synthesized liquid, and a mixture of different liquids are used. A liquid, a mixed liquid of powder and granular material, or the like may be used.

Further, a brushless DC servomotor or the like may be used as the electric motor 13 in addition to the AC servomotor, and a current sensor such as a Hall element is often used as the drive current detecting member 39. Further, in each of the above embodiments,
The main controllers 41, 51 and the control devices 30, 50,
Although the main unit 61 and the control unit are separated into separate units, the present invention is not limited to this, and the main controller and the control device may be integrated in the same unit. Alternatively, they may be integrated into the same computer system. In such a case, the flow control command Qc and the pressure command Pc are generated in the control electronic circuit and may be transferred between boards, between circuit blocks, or between routines. is there.

In the above embodiment, the total control amount Tc is obtained in the dimension of torque. However, the total control amount Tc may be calculated by a torque equivalent amount substantially proportional to the torque. However, the processing contents of the control amount distribution unit 34 and the like do not have to be complicated. Further, when distributing the total control amount Tc, the total control amount Tc is decomposed into a part weaker than the predetermined value A and a part stronger than the predetermined value A, but the distribution method is also limited to this. Not something. For example, using the motor torque If from the drive current detection member 39,
Alternatively, another torque detecting means is separately added to detect the torque of the rotating shaft 14 and the output shaft 15 and compare the torque with a predetermined value A. When the torque is weaker than the predetermined value A, full control is performed. The entire amount Tc may be assigned to the motor control means 37. In this case, since the total control amount Tc is released from the dimension of torque, another dimension such as speed or position may be given, and it becomes easy to perform motor control or the like by speed control or the like.

[0051]

As is apparent from the above description, in the hydraulic apparatus according to the first solution of the present invention, the electric motor is integrally added to the hydrotransformer via the common shaft, There is an advantageous effect that a hydrotransformer that can operate stably even at a minute output without sacrificing such as switching to an auxiliary pump or increasing energy consumption can be realized.

Further, in the hydraulic device according to the second solution of the present invention, the control is performed such that the priority is given to the drive by the electric motor which is easy to stabilize the operation at the time of minute output, There is an advantageous effect that the hydrotransformer operates stably even at a minute output without sacrificing such as switching to the auxiliary pump or increasing energy consumption.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a hydraulic device according to the present invention.
(A) is a partial vertical sectional view of a hydrotransformer with a servomotor, and (b) is a circuit diagram of a hydraulic pressure source and the like incorporating the same.

2A is a block diagram of a control device for a hydrotransformer, and FIG. 2B is a circuit diagram of an injection molding machine as a typical application example.

FIG. 3 is a flowchart showing a processing procedure of a control device of a hydrotransformer in a second embodiment of the hydraulic device of the present invention.

FIG. 4 is a block diagram of a control device for a hydrotransformer according to a third embodiment of the hydraulic device of the present invention.

FIG. 5 is a circuit diagram of a hydraulic pressure source or the like incorporating a hydrotransformer with a servomotor in a fourth embodiment of the hydraulic device of the present invention.

FIG. 6 is a circuit diagram of a conventional injection molding machine and a hydraulic pressure source.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Hydrotransformer (hydraulic device) 11 Hydraulic pump (liquid pump, positive displacement pump) 12 Hydraulic motor (liquid motor, positive displacement motor) 13 Electric motor (electric motor, servomotor) 14 Rotary axis (common axis, common axis) , Common axis, rigid axis,
15 Output shaft (rotary output shaft of electric motor) 16 Electromagnetic proportional control valve (servo valve, pilot valve of variable capacity mechanism) 17 Variable capacity mechanism (means for changing volume by changing tilt angle of swash plate, etc.) 18) Capacity detection means (means for detecting the tilt angle of the swash plate) 19 Rotation speed detection means (encoder, tachometer) 20 Hydraulic pressure source (hydraulic device) 21 Tank (liquid tank) 22 Small electric motor (low Output electric motor) 23 Small pump (Small capacity hydraulic pump) 24 Check valve (Check valve) 25 Accumulator (Accumulator) 26 Liquid flow path (Pressure liquid supply line such as piping and perforation) 30 Control device ( Control device for hydrotransformer) 31 flow rate detection section (feedback section, calculation means) 32 difference calculation section (error calculation section, calculation means) 33 flow rate control calculation section (control amount calculation section, Means) 34 control amount distributing unit (control amount dissolving unit + control amount distributing unit, distributing unit) 35 displacement control unit (feedback control, displacement control unit of hydraulic motor) 36 electromagnetic drive unit (driver and power of solenoid proportional control valve) Electronic circuit 37 Motor control section (feedback control, electric motor control means) 38 Motor drive section (motor driver, inverter, power electronic circuit) 39 Drive current detecting member (drive torque detecting means of electric motor) 40 Injection molding machine (liquid) Pressure system) 41 main controller (sequence control means, application procedure control means) 42 mold clamping device 43 ejection device 44 injection device 45 weighing device 46 nozzle moving device 50 control device (control device of hydrotransformer) 51 main controller (sequence control means) , Application procedure control means) 52 Pressure gauge (detection means) Feedback means) 53 difference calculation unit (error calculation unit, calculation unit) 54 pressure control calculation unit (control amount calculation unit, calculation unit) 55 comparison unit (comparator, determination unit, determination unit) 56 selection unit (switch circuit, selector, Switching means) 60 Hydraulic device 61 Control device (Control device of hydrotransformer) 62 Hydraulic pressure source (Hydraulic device) 63 Electromagnetic proportional control valve (Pilot valve of variable capacity mechanism) 64 Variable capacity mechanism (Tilt angle of swash plate) Means for changing the volume by changing etc.) 65 capacity detection means (means for detecting the tilt angle of the swash plate) 70 injection molding machine (hydraulic system) 71 hydraulic pressure source (hydraulic device) 72 controller (hydro) Transformer control device) 73 Motor driver 74 Servo motor 75 Auxiliary pump 76 Switching valve (solenoid valve, open / close valve) A Predetermined value (exceeding static friction) Qc Flow control command Pc Pressure control command Tc Total control amount (control amount required to follow control command) Ic Motor control amount (one of electric motor torque control command and distribution control amount) If Motor torque ( Current detection signal, feedback value) I Motor drive current Cc Capacity control amount (the other of hydraulic motor capacity control command and distribution control amount) Cf Detection capacity (detection signal such as tilt angle of swash plate, feedback value) C proportional Control current Rf Rotation speed

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kunichi Hyodo 2-16-46 Minami Kamata, Ota-ku, Tokyo F-term in Tokimec Co., Ltd. (Reference) 3H045 AA08 AA09 AA12 AA24 AA34 BA19 CA28 DA10 3H075 AA02 BB03 CC12 DB03 DB42 EE03 EE14 3H089 AA01 AA21 AA32 BB04 BB10 BB14 BB17 CC01 CC11 DA02 DA03 DA04 DA14 DA15 DB63 DC02 EE35 EE36 FF10 FF12 GG01 GG02 JJ03 JJ05 JJ06 4F206 AR14 JA07 JM16 JT01 JT03 JT04

Claims (10)

[Claims] 1. A hydraulic device comprising a rotary hydraulic pump, a hydraulic motor sharing a rotary shaft with the rotary pump, and an electric motor having an output shaft connected to the rotary shaft. 2. A control device for sharing the driving force of the hydraulic pump between the hydraulic motor and the electric motor and allocating a minute amount to the electric motor first. Item 6. The hydraulic device according to Item 1. 3. A rotary hydraulic pump capable of operating as a motor, a hydraulic motor capable of operating as a pump, a rotary shaft shared by the hydraulic pump and the hydraulic motor, and A hydraulic device comprising: an electric motor having an output shaft connected thereto. 4. The hydraulic device according to claim 1, wherein a capacity variable mechanism is added to one or both of the hydraulic pump and the hydraulic motor. 5. A motor control means for controlling the rotation of the electric motor, a capacity control means for controlling the capacity variable mechanism, and a control amount for following based on a received or generated control command. 5. The hydraulic apparatus according to claim 4, further comprising a calculating unit, and a distribution unit that distributes the control amount to the motor control unit and the displacement control unit. 6. The control means calculates the control amount as a torque or a torque equivalent amount, and when the control amount is smaller than a predetermined value, the distribution means allocates the entire control amount to the motor control means. The hydraulic device according to claim 5, wherein: 7. An electric motor, comprising: a torque detecting means for detecting an output torque or a corresponding amount of the electric motor. When the torque is smaller than a predetermined value, the distributing means allocates the entire amount of the control amount to the motor control means. A hydraulic device according to claim 5, characterized in that: 8. The liquid according to claim 6, wherein the predetermined value is set to be larger than the static friction torque of the rotating shaft and smaller than the maximum value of the output torque of the electric motor. Pressure device. 9. The liquid according to claim 8, further comprising a hydraulic pump having a smaller capacity than the hydraulic pump, and an accumulator connected to a liquid flow path extending from the hydraulic pump to the hydraulic motor. Pressure device. 10. The apparatus according to claim 1, further comprising a hydraulic pump having a smaller capacity than said hydraulic pump, and an accumulator connected to a liquid flow path extending from said hydraulic pump to said hydraulic motor. A hydraulic device according to any one of the preceding claims.