JP2007182969A - Hydraulic pressure generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic pressure generating device that can scale down and simplify a design of a driving control system without causing practical problems, and undergoes no restrictions by piping or wiring. <P>SOLUTION: The hydraulic pressure generating device includes: a hydraulic pressure generating unit having a reservoir tank, a supermagnetostrictive hydraulic pump and an electromagnetic switching valve; and a control section for driving control of the supermagnetostrictive hydraulic pump and the electromagnetic switching valve. The hydraulic pressure generating device further includes an electromagnetic inductive transmission unit arranged between the control section and the hydraulic pressure generating unit. The electromagnetic inductive transmission unit transmits electric power and control signals for the driving control without contact, while using an induction field as a transmission medium. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydraulic pressure generator that supplies hydraulic oil to a hydraulic cylinder for driving an actuator, for example.

  In the field of machine tools, construction machinery, etc., hydraulic pressure is generated by driving the hydraulic pump with a general-purpose motor installed at a position away from the target machine and transmitting the generated hydraulic pressure through piping over a long distance. It was.

  As a hydraulic pressure generator, for example, as shown in FIG. 9, a hydraulic pump is driven by an electric motor composed of a general-purpose motor, pumping up oil in an oil tank to generate an oil pressure, and this oil pressure advances the rod of the hydraulic cylinder. And those that are retracted in the opposite direction have been used (see, for example, Patent Document 1).

  This hydraulic pressure generator has an electromagnetic switching valve for switching the moving direction of the rod, and the check valve and the rod are moved forward in the piping between the electromagnetic switching valve and the rod advance side oil chamber of the hydraulic cylinder. A forward pressure switch is provided to detect the completion, and the pipe between the electromagnetic switching valve and the hydraulic cylinder back rod side oil chamber is moved backward to detect the completion of the rod backward movement. A pressure switch is provided. Furthermore, a relief valve is provided in the pipe between the hydraulic pump and the electromagnetic switching valve.

  In the conventional system, as described above, the hydraulic pump directly connected to the general-purpose motor is rotated at a high speed to suck up and pressurize the hydraulic oil in the hydraulic tank. When a predetermined time has elapsed after the pump starts rotating by the motor, the hydraulic pressure starts to rise, so the hydraulic fluid pressurized by turning on the clamp side valve of the electromagnetic switching valve is supplied to the hydraulic cylinder through the hydraulic line, The cylinder rod is moved forward, and this forward force becomes the workpiece clamping force.

  The verification of the completion of clamping is more surely performed by the load cell embedded with the actuator, but as a simple method, it can also be performed by confirming that the pressure switch in the hydraulic circuit in which the pressure corresponding to the clamping force is set is turned on. When the pressure switch reaches the set value, the clamp side valve that was on is turned off, but the forward pressure of the cylinder rod is maintained by the pilot check valve for clamping, so even if the motor is stopped and the hydraulic pump is stopped The workpiece clamp state is maintained. Therefore, in subsequent processes until unclamping, for example, workpiece cutting, polishing, and welding assembly, transmission of power and control information is not required unless state monitoring or in-process clamping correction is performed.

  The unclamping operation is performed similarly to the clamping operation, but through a separate flow path. First, the general-purpose motor is driven to rotate the hydraulic pump, and the unclamping valve of the electromagnetic switching valve is turned on after a predetermined time has elapsed. As a result, the rod of the hydraulic cylinder starts to move backward, and the oil in the forward oil chamber returns to the oil tank. However, the completion of the backward movement can be confirmed by confirming that the unclamping pressure switch of the hydraulic circuit is turned on. After confirming that the pressure switch is turned on, the unclamping valve is turned off. However, the cylinder rod retraction pressure is held by the unclamping pilot chuck valve, so the pressure state is maintained even if the motor drive is stopped as in the case of clamping. Thus, the unclamping work for removing the workpiece becomes possible.

JP-A-9-77395

  On the other hand, recently, distributed hydraulic pressure generation by servo motor drive is being adopted with the aim of energy saving, but the conventional motor-driven hydraulic pressure generators as described above are excessive in the size and weight of motors and peripheral electrical devices. In order to reduce the size and weight of the entire system, the hydraulic tank can be integrated with the hydraulic pump, and the general-purpose motor for driving can be made as small as possible to integrate the hydraulic pump and the shaft. However, since such a design is not suitable for practical use, it has been difficult to reduce the size and weight in practice.

  In view of the above problems, an object of the present invention is to provide a hydraulic pressure generator capable of downsizing the device design and simplifying the design of the drive control system without causing practical problems.

  In order to achieve the above object, a hydraulic pressure generator according to the invention described in claim 1 includes a reservoir tank for supplying / recovering hydraulic oil and a magnetostrictive element in the coil by a magnetic force generated by energizing the drive coil. A giant magnetostrictive hydraulic pump that discharges hydraulic oil sucked into the cylinder from the reservoir tank to the load side by changing the volume and reciprocatingly driving the plunger piston in the cylinder along with the volume change, and the giant magnetostrictive hydraulic pressure A hydraulic pressure generating unit that switches the direction of hydraulic oil from the pump by an electric signal; and a control unit that controls driving of the giant magnetostrictive hydraulic pump and the electromagnetic switching valve. Inductive transmission that performs power transmission and control signal transmission for drive control in a contactless manner using an induction electromagnetic field as a transmission medium between the hydraulic pressure generating unit and the hydraulic pressure generating unit One in which further comprises a knit.

  According to a second aspect of the present invention, in the hydraulic pressure generating device according to the first aspect, the cylinder rod is advanced and retracted by the operating pressure oil supplied from the hydraulic giant magnetostrictive hydraulic pump. A hydraulic cylinder is further provided, and the hydraulic cylinder, the hydraulic pressure generating unit, the control unit, and the electromagnetic induction transmission unit are mounted in a single unit structure.

  According to a third aspect of the present invention, there is provided the hydraulic pressure generating apparatus according to the first or second aspect, wherein the electromagnetic induction transmission unit is an electromagnetic for inductive transmission in a mutually stationary state. A pair of coil heads for coupling is provided, and the pair of coil heads is characterized in that a primary winding and a secondary winding are individually wound around a pot type core made of a high-frequency magnetic material.

  According to a fourth aspect of the present invention, there is provided the hydraulic pressure generating apparatus according to the first or second aspect, wherein the electromagnetic induction transmission unit is a pair of coils that perform electromagnetic coupling for induction transmission. The pair of coil heads includes a high-frequency magnetic material core that opens and closes via a hinge, and a primary coil that is fixed to a predetermined relative position that obtains the electromagnetic coupling state when the core is closed. And a hinge-type core having a secondary coil.

The hydraulic pressure generator according to the present invention uses a giant magnetostrictive hydraulic pump that utilizes a change in volume depending on whether or not a giant magnetostrictive element is energized as a hydraulic pump for supplying hydraulic fluid to a hydraulic cylinder for driving an actuator. Therefore, it is possible to construct a compact hydraulic unit that can control the flow rate by frequency control of voltage on / off without using an electric motor, and between the control unit that drives and controls the hydraulic pump and the electromagnetic switching valve, and the hydraulic pressure generating unit. The electromagnetic induction transmission unit can be provided, and power transmission and control signal transmission for driving control of the giant magnetostrictive drive unit and the electromagnetic switching valve can be performed in a non-contact manner using an induction electromagnetic field as a transmission medium. In this way, by adopting a combination of oil pressure generation by giant magnetostrictive actuator and inductive contactless transmission technology, autonomous of distributed hydraulic jigs (for example, hydraulic jig pallets) that could not be realized with conventional piping, wiring, and contact transmission systems Realization of distributed control makes it possible to achieve no loss and no wiring in bad environments such as cutting and welding, and it is not only strong in the environment, but also enables automation and flexible changes in processing and assembly processes.
Especially for hydraulic jig pallets, etc., in addition to sequence information for generating clamping force (for example, pressure switch and clamping force measurement load cell), state quantity sensor data including the workpiece itself and pallet position and the surrounding environment Since real-time feedback can be performed without being influenced, it is possible to perform adaptive precision machining and assembly by correcting the effects of the workpiece cutting reaction force and mechanical thermal strain by passing these pieces of information to an NC machine or robot.
Therefore, the present invention is greatly expanded to the realization of closed loop machining and assembly work by intelligent drive control and self-diagnosis function by the CPU mounted on the distributed hydraulic jig and real-time feedback of the work state detected by the sensor on the jig. There is an effect that it is possible to go.

  The present invention relates to a hydraulic pressure generating unit for supplying hydraulic oil pressurized by a hydraulic pump to a load pipe such as a hydraulic cylinder for driving an actuator through an electromagnetic switching valve in a hydraulic pressure generating unit. As a result, the volume of the giant magnetostrictive element in the drive coil of the giant magnetostrictive drive unit is changed by energizing the drive coil to change the volume. A giant magnetostrictive hydraulic pump that discharges working pressure oil from a reservoir is adopted.

  As a result, in the hydraulic pressure generator of the present invention, a compact hydraulic unit capable of controlling the flow rate by voltage on / off frequency control without using an electric motor can be constructed, and the entire apparatus can be downsized. .

  Furthermore, as shown in FIG. 6, the present invention is for transmitting power and information signals to the hydraulic pressure generating unit side by non-contact communication from the control unit for driving and controlling the giant magnetostrictive hydraulic pump and the electromagnetic switching valve without contact. The electromagnetic induction transmission system is used, and between the control unit and the hydraulic pressure generation unit, power transmission and control signal transmission are performed for driving control of the giant magnetostrictive driving unit and the electromagnetic switching valve. As an electromagnetic induction transmission unit.

  Therefore, in the present invention, since the wiring and piping between the control unit and the hydraulic pump unit, which are necessary in the conventional contact transmission type, can be omitted, the entire hydraulic pressure generator can be downsized. Piping and non-wiring are less likely to be adversely affected by the actuator driving environment such as cutting and welding, and as described above, the super-magnetostrictive type of hydraulic pump is adopted, enabling autonomous distributed drive control and actuator drive. Work efficiency can be improved by distributed processing.

  Therefore, as described above, the hydraulic pressure generating unit, the control unit, and the electromagnetic induction transmission unit capable of simplifying the device design and miniaturizing and capable of distributed drive control are supplied with hydraulic pressure oil from the giant magnetostrictive hydraulic pump. The cylinder rod for driving the actuator can be mounted in a single unit structure together with the hydraulic cylinder in which the cylinder rod for driving the actuator is moved forward and backward. It can be easily incorporated as a source, contributing to the realization of autonomous distributed control of these jigs. In this case, if the reservoir tank is integrally formed in the same housing as the giant magnetostrictive hydraulic pump, it is easier to combine the parts when configuring one small hydraulic pressure generator.

  The electromagnetic induction transmission is performed between two electromagnetic induction coils, and a high-frequency induction electromagnetic field generated in the vicinity of one of the coils is used as a transmission medium for power and information signals. That is, electric power is supplied by inducing electric power when the other coil receives an electromagnetic field generated by applying an alternating current to one coil. Usually, the distance between coils can be transmitted up to about 20 cm.

  Accordingly, the electromagnetic induction transmission unit of the present invention also includes a pair of coil heads that perform electromagnetic coupling for induction transmission in a stationary state opposite to each other, and each of the coil heads has a pot type core made of a high frequency magnetic material. The form which winds and forms a primary winding and a secondary winding separately is mentioned.

  In order to compensate for a voltage drop due to leakage inductance, a resonant inverter is preferably used for the inverter used for generating and transmitting high-frequency power according to the present invention. In this case, a capacitor connected in series is inserted on the secondary side of the transmission unit, and the high-frequency component in the current can be reduced to reduce the switching loss, the voltage change rate, and the current change rate. However, since the series capacitance is determined by the switching frequency, there is a concern about deviation from resonance due to the change in leakage inductance. However, if a coil head consisting of the above pot-type core is used, the change in leakage inductance with respect to the gap length Is practically not a problem.

  However, in the pot type core type, good transmission characteristics such as power transmission efficiency and information transmission speed cannot be obtained unless the inter-core gap and the relative positional relationship are set with high accuracy. If the configuration is such that the primary coil and the secondary coil can be fixed with high precision and good reproducibility to a predetermined relative positional relationship where the electromagnetic coupling can be obtained, good transmission characteristics are always ensured. be able to.

  As such a configuration, the high-frequency magnetic material core has a shape that opens and closes via a hinge, and when the core is in a closed state, the primary coil and the secondary coil obtain the electromagnetic coupling state in advance. A coil head composed of a hinge-type core fixed to the relative position is simple. Specifically, for example, by forming a primary coil by winding a primary winding on one of the core members that opens and closes via a hinge, and closing the core so that a separate secondary coil is sandwiched between the open ends of the core The structure which a secondary coil positions and fixes with respect to a primary coil is mentioned.

  In the hydraulic pressure generator of the present invention, the high frequency voltage supplied from the high frequency inverter and transmitted to the hydraulic pressure generation unit side through the transmission unit is once converted to direct current by a rectification and smoothing circuit, and then mounted on the inverter. Thus, the super magnetostrictive element of the super magnetostrictive drive unit is converted into low-frequency AC power that causes the maximum displacement.

  Also, with this hydraulic pressure generator, half-duplex in HDLC (High-level Data Link Control) format, considering high-frequency signal generation and transmission characteristics with transmission speeds that allow servo control level motion control and real-time sensor feedback. It is desirable to adopt a communication method.

  In such a frequency range of information transmission, the equivalent circuit and the stray capacitance existing in the transmission unit must be taken into consideration when examining the equivalent circuit. Further, when the feeder line from the transmission unit to the signal source is long, it is necessary to treat it as a distributed constant line in which signal attenuation along the transmission line exists, and to consider the response characteristics by including it in this equivalent circuit. The broken line in the frequency characteristics for information transmission is approximately given by the equivalent circuit constants. From this characteristic, the information frequency band that can be transmitted is known, and coupling is performed based on the transmission speed requirement (usually 1 MBps or more) required for motion control. Requirements for dimensions are required. Based on the required specifications as described above, the external dimensions of the coupled / separated electromagnetic induction transmission unit are determined.

  In addition, the most important issue in the simultaneous transmission of power and information is to ensure a high signal-to-noise ratio as much as possible. However, as the geometric distance between the power transmission unit and the information transmission unit increases, the superimposition increases. Although it is natural that the noise voltage level decreases, the distance cannot be increased as much as possible. Therefore, by using a resonant inverter as described above and electromagnetic shielding, the signal-to-noise ratio can be improved and communication errors can be prevented during transmission.

  Note that the present invention is not limited to the case where power transmission and information transmission are performed through transmission paths that are independent and close to each other as described above. In the present invention, the power transmission and the information transmission are first overlapped in synchronization. It is also possible to adopt a superposition transmission method for transmitting through the same taxiway.

  FIG. 1 shows a control system in the overall configuration of a hydraulic pressure generator according to an embodiment of the present invention. The hydraulic pressure generator is installed between a hydraulic pressure generating unit 1 for driving the actuator 5, a control unit 20 for driving and controlling the hydraulic pressure generating unit 1, and between the control unit 20 and the hydraulic pressure generating unit 1. The control unit 20 mainly includes a power for driving control and an electromagnetic induction transmission unit 30 for non-contact induction transmission of information and information to the hydraulic pressure generation unit 1.

  The hydraulic pressure generating unit 1 supplies hydraulic oil pressurized by the giant magnetostrictive hydraulic pump 2 to the hydraulic cylinder 4 via the electromagnetic switching valve 3, whereby the cylinder rod of the hydraulic cylinder 4 moves forward and backward. Thus, the actuator 5 is driven. At this time, the giant magnetostrictive hydraulic pump 2 and the electromagnetic switching valve 3 are driven and controlled by the power and information transmitted from the control unit 20.

  As shown in FIG. 2, the giant magnetostrictive hydraulic pump 2 used in this embodiment is inserted in the same housing 5 so that the giant magnetostrictive element 7 can be extended and contracted in a bobbin around which a drive coil 6 is wound. The giant magnetostrictive drive section and the plunger 8 connected to the end of the giant magnetostrictive element 7 extend in response to the magnetic force generated by energizing the drive coil 6 and disappears due to the deenergization. And a pump unit configured to reciprocate and slide in the pump chamber 9 according to the expansion and contraction motion caused by the volume change of the giant magnetostrictive element 7 that contracts to the original dimension in response to the above.

  The pump chamber 9 is connected to the reservoir tank 11, and when the volume in the pump chamber 9 is expanded in accordance with the reciprocal sliding of the plunger 8 accompanying the expansion and contraction of the giant magnetostrictive element 7 as described above, Reservoir oil is introduced from the reservoir chamber 12 whose volume is pressurized by the pressing plate 13 by the biasing force of the spring 14 of the tank 11, and the hydraulic oil is supplied via the check valve 10 when the volume of the pump chamber 9 is reduced. Is discharged to the hydraulic cylinder 4 side.

  That is, in this hydraulic pressure generating apparatus, a compact hydraulic system can be constructed without using an electric motor by employing the giant magnetostrictive hydraulic pump 2 that can obtain a pumping action by the expansion and contraction motion of the giant magnetostrictive element 7.

  In the giant magnetostrictive hydraulic pump 2 as described above, a pumping action occurs depending on whether or not the drive coil 6 is energized. Therefore, the energization of the drive coil 6 is controlled on / off with a predetermined frequency current so that the giant magnetostrictive type is obtained. The flow rate of the hydraulic oil discharged from the hydraulic pump 2 can be controlled. Further, the discharge port of the hydraulic pump 2 and the hydraulic cylinder 4 are connected via an electromagnetic switching valve 3, and forward / backward movement of the hydraulic cylinder rod can be controlled by controlling the electromagnetic switching valve 3 on and off. Therefore, by using such a giant magnetostrictive hydraulic pump 2, autonomous distributed drive control in the hydraulic pressure generator can be realized.

  In addition, the electromagnetic induction transmission unit 30 in the present embodiment is mainly composed of a pair of coil heads that perform electromagnetic coupling for induction transmission in a stationary stationary state. Inductive transmission uses a high-frequency induction electromagnetic field generated by applying an alternating current to one coil as a transmission medium, and the other coil receives the electromagnetic field to induce electric power to supply power. Is.

  In this embodiment, a resonant inverter as shown in FIG. 3 is used as an inverter used for high-frequency power generation and transmission. This inverter is characterized by the operation of a capacitor connected in series to the secondary side of the transmission unit. This inverter reduces high-frequency components in the current to reduce the switching loss, voltage change rate, and current change rate, thereby compensating for the voltage drop due to leakage inductance.

  In the present embodiment, the high-frequency voltage supplied from such a high-frequency inverter and transmitted to the hydraulic unit 1 via the transmission unit 30 is once converted to direct current by a rectifier and then magnetostricted by the mounted inverter of the hydraulic unit 1. The element is converted into low-frequency AC power that causes the maximum displacement. Further, in this embodiment, by adopting half-duplex communication in the HDLC format, it is possible to obtain a transmission speed capable of motion control at the servo control level and real-time sensor feedback.

  Further, as the configuration of the coil head constituting the electromagnetic induction transmission unit 30, a configuration using a pot-type core as shown in FIG. 4 can be used. In the coil head using the pot type core, good transmission characteristics such as power transmission efficiency and information transmission speed cannot be obtained unless the inter-core gap and the relative positional relationship are set with high accuracy.

  Therefore, if a hinge-type core as shown in FIG. 5 is used, the primary coil and the secondary coil can be fixed to a predetermined relative positional relationship in which electromagnetic coupling is obtained with high accuracy and good reproducibility. Good transmission characteristics can be ensured. In the coil head using this hinge-type core, the cores made of high-frequency magnetic material are opened and closed with each other via a hinge, and a primary coil is formed by winding a primary winding on one side of the opening and closing core member. By closing the core so that the secondary coil is sandwiched between the open ends of the core, the primary coil and the secondary coil are respectively fixed at predetermined relative positions to obtain an electromagnetic coupling state.

  In the hydraulic pressure generator according to the present embodiment having the above-described configuration, the transmission of power and information from the control unit 20 to the hydraulic pressure generation unit 1 is a non-contact transmission type via the electromagnetic induction unit 30. Wiring and piping to and from the hydraulic pressure generating unit 1 can be omitted, and the entire hydraulic pressure generating device can be reduced in size, and at the same time, it is less susceptible to adverse effects from the actuator driving environment such as cutting and welding. Furthermore, as described above, since a giant magnetostrictive hydraulic pump is employed, autonomous distributed drive control is possible, and work efficiency can be improved by distributed processing during actuator drive.

  As described above, the hydraulic pressure generating unit, the control unit, and the electromagnetic induction transmission unit capable of reducing the device design with no piping and no wiring and capable of distributed drive control are mounted in the same housing, and are combined into one small hydraulic pressure. It can be configured as a generator and can be applied to various automatic jigs.

  For example, if the work itself, the position of the pallet, and the status monitoring sensor data can be fed back in real time without being influenced by the surrounding environment, in addition to the sequence information from the pressure switch for generating the clamping force by hydraulic pressure, the clamping force measurement load cell, etc. An automatic jig such as an NC machine as shown in Fig. 7 that detects the state of a workpiece or jig by mounting a sensor on it, or an automatic as shown in Fig. 8 (quoted from the International Machining Technology Project (IMS) report) By incorporating this hydraulic pressure generator into the robot as a drive source, adaptive precision machining that compensates for the effects of workpiece cutting reaction force and mechanical thermal strain becomes possible.

It is the flowchart which showed the whole structure of the hydraulic pressure generator by one Example of this invention with the control system. It is a schematic block diagram of the giant magnetostrictive hydraulic pump used in a present Example. It is an electric circuit diagram of the inverter used for high frequency electric power generation and transmission in a present Example. It is a schematic diagram which shows schematic structure of the pot core type coil as an example of the coil head used for the electromagnetic induction transmission unit in a present Example, (a) is a front view of one coil head, (b) is longitudinal side sectional drawing. It is. It is a schematic diagram which shows schematic structure of the hinge core type coil as another example of the coil head used for the electromagnetic induction transmission unit in a present Example, (a) is explanatory drawing which shows the state before coupling | bonding, (b) is coupling | bonding. It is explanatory drawing which shows a completion state. It is a schematic diagram explaining the non-contact transmission by the electromagnetic induction transmission unit of this invention. It is explanatory drawing which shows an example of the automatic jig | tool at the time of using the hydraulic pressure generator by a present Example. It is a schematic block diagram showing an application example of an automatic jig equipped with a hydraulic pressure generator according to the present embodiment to an automatic robot. It is a hydraulic circuit diagram which shows an example of the conventional hydraulic pressure generator.

Explanation of symbols

1: Hydraulic pressure generating unit 2: Giant magnetostrictive hydraulic pump 3: Electromagnetic switching valve 4: Hydraulic cylinder 5: Actuator 6: Drive coil 7: Giant magnetostrictive element 8: Plunger 9: Pump chamber 11: Reservoir tank 12: Reservoir chamber 13: Holding plate 14: Spring 20: Control unit 30: Electromagnetic induction transmission unit

Claims (4)

By changing the volume of the giant magnetostrictive element in the reservoir tank for supplying and collecting the hydraulic oil and the magnetic force generated by energizing the drive coil, and reciprocatingly driving the plunger piston in the cylinder in accordance with the volume change Hydraulic pressure generation having a giant magnetostrictive hydraulic pump that discharges hydraulic oil sucked into the cylinder from the reservoir tank to the load side, and an electromagnetic switching valve that switches the direction of the hydraulic oil from the giant magnetostrictive hydraulic pump with an electric signal Unit,
A control unit that drives and controls the giant magnetostrictive hydraulic pump and the electromagnetic switching valve;
An electromagnetic induction transmission unit that performs power transmission and control signal transmission for the drive control in a non-contact manner using an induction electromagnetic field as a transmission medium is provided between the control unit and the hydraulic pressure generating unit. Hydraulic pressure generator.   The hydraulic cylinder further includes a hydraulic cylinder in which a cylinder rod is moved forward and backward by hydraulic pressure oil supplied from the hydraulic giant magnetostrictive hydraulic pump, and the hydraulic cylinder, the hydraulic pressure generating unit, the control unit, and the electromagnetic induction transmission unit are simply combined. The hydraulic pressure generator according to claim 1, wherein the hydraulic pressure generator is mounted in a single unit structure.   The electromagnetic induction transmission unit includes a pair of coil heads that perform electromagnetic coupling for induction transmission in a stationary state opposite to each other, and the pair of coil heads are individually wound on a high-frequency magnetic material pot-type core. The hydraulic pressure generator according to claim 1 or 2, wherein the hydraulic pressure generator is wound with a secondary winding. The electromagnetic induction transmission unit includes a pair of coil heads that perform electromagnetic coupling for inductive transmission, and the pair of coil heads is in advance in a closed state of a pair of high-frequency magnetic material cores that are opened and closed with hinges. A hinged core having a primary coil and a secondary coil fixed in a defined relative positional relationship;
The primary coil and the secondary coil of the hinge-type core coil are fixed in a relative positional relationship that provides sufficient electromagnetic coupling between the two coils in the closed state of the core to ensure proper transmission characteristics. The hydraulic pressure generator according to claim 1 or 2, wherein the hydraulic pressure generator is characterized.

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