JP4185082B2 - Hydraulic source distributed hydraulic unit using variable piston pump in oil immersion state - Google Patents

Description

  The present invention is a hydraulic unit in a hydraulic source distributed hydraulic system in which necessary hydraulic units are distributed and individually provided for each actuator, and the hydraulic pump is stored in an oil tank in an oil-immersed state in a compact manner and has multiple functions. The present invention relates to a hydraulic pressure source distributed type hydraulic unit that uses a variable piston pump capable of precise control in an oil immersed state.

  Conventionally, actuators are provided in various mechanism operating parts such as various industrial machines utilizing hydraulic devices. As means for supplying hydraulic oil to this actuator, a hydraulic source centralized system and a hydraulic source distributed system are known. The hydraulic power source centralized system supplies the hydraulic flow direction, pressure and flow required by each actuator to a plurality of hydraulic actuators from one hydraulic unit via piping connecting the hydraulic unit and each actuator. System. In this concentrated hydraulic power source system, not only pipe loss according to the piping distance is generated, but also the operation of a plurality of actuators is considered, and a large design margin is required for a hydraulic pump or the like serving as a hydraulic power source. For this reason, there is a disadvantage that the loss increases depending on the operating condition of the load.

Further, in this hydraulic source centralized system, as shown in block diagram illustrating the principal components of a hydraulic source centralized system of Figure 12, a variable piston pump 32 disposed in the oil tank 31 top, a plurality of such pumps regulators 33, 34 Control is performed by selecting and using a dedicated pump regulator in accordance with the control to be performed from among the pump regulators. Therefore, it is necessary to replace the dedicated pump regulator every time the control contents are different. Further, since it is installed at a location away from each actuator, there are few space restrictions, and various control mechanisms such as a variable piston pump 32, a pump regulator 33 (or 34), an electromagnetic valve 35, etc. disposed on the outer surface of the oil tank 31. Even if there is an overhanging portion or the like, it can be dealt with by increasing the size of the oil tank 31. Therefore, there is a problem that the installation space becomes larger than necessary, and the amount of hydraulic oil increases as the oil tank 31 becomes larger. In FIG. 12 , the mesh portion 36 represents an installation space for the oil tank 31.

  On the other hand, the distributed hydraulic source system distributes the necessary hydraulic units for each actuator separately and supplies them to each actuator from a dedicated hydraulic unit via a pipe connecting the hydraulic unit and each actuator. System. Therefore, the hydraulic pump, which is the hydraulic source, and the control valve are paired with the actuator, and the operation on the hydraulic source side can be uniquely determined according to the required energy of the actuator, so the hydraulic source can be operated efficiently and loss occurs Can be kept to a minimum. In addition, the hydraulic source can be arranged in the immediate vicinity of the actuator, the hydraulic piping length is short, and the pipe loss is advantageous compared to the centralized system. There are two types of this hydraulic power source distributed system: a type in which the hydraulic unit is attached to the actuator integrally, and a type in which the hydraulic unit is provided separately. The control mechanism is individually designed for each actuator. The same.

  Recently, a hydraulic source distributed system in which a hydraulic source and a control unit are integrally formed in a hydraulic cylinder as an actuator has attracted attention, and the present inventor has previously first integrated a hydraulic unit into a hydraulic cylinder. A hydraulic cylinder device in a distributed system has been provided (see Patent Document 1).

Further, in order to reduce the size of the oil tank in the hydraulic power source distributed system to the minimum necessary, the present inventor has determined the amount of oil increase / decrease during operation, the amount of residual oil in the oil tank, the air pool in the oil tank, etc. In consideration of this, it has been proposed to use an oil tank having a capacity of about three times the amount of increase / decrease in oil amount when the hydraulic cylinder is operated (see Patent Document 2).
JP 2001-124033 A JP 2001-317507 A

  As described above, the hydraulic source distributed hydraulic unit is an independent distributed hydraulic system in which a hydraulic source and a control unit are integrated with a hydraulic cylinder as an actuator, and the hydraulic system itself is independent in a self-contained form. This eliminates the need for piping from a large hydraulic unit to each hydraulic cylinder as in the prior art, and is free from piping work and flushing work, and there is an advantage that troubles such as pressure loss and oil leakage in the piping do not occur. Furthermore, there is an advantage that the hydraulic pump can be stored in an oil tank in which hydraulic oil is stored in an oil-immersed state, and space can be saved and noise can be reduced.

However, when using a variable displacement piston pump, it is indispensable to equip various types of pump regulators according to the control to be performed to control the hydraulic pump. Cannot accommodate a pump regulator to which various control mechanisms are added in space. FIG. 10 is a configuration diagram of the main part of a hydraulic source distributed system using an oil tank 37 having a capacity of about three times the amount of oil increase / decrease when the actuator is operated. The variable piston pump 38 is integrated with the pump regulator 39. When it is installed in the oil tank 37, it can be seen that it cannot be stored in the oil tank 37 due to the overhang of the pump regulator 39 or the like. Reference numeral 40 denotes an electromagnetic direction flow control valve and a laminated valve, 41 an electric motor, 42 a manifold, 43 a front cover, and a mesh portion 44 an installation space for the oil tank 37.

Therefore, in order to store these in the oil tank, it is necessary to secure a space for storing the hydraulic pump and the pump regulator in the oil tank. There is a problem that a tank must be selected. FIG. 11 is a main part configuration diagram in which a part of a hydraulic source distributed system is broken when an oil tank having a capacity for accommodating a hydraulic pump or the like is used. Components having the same configuration as FIG. 10 are the same. The description is abbreviate | omitted and attached | subjected. Since the variable piston pump 38 is housed in the oil tank 45 integrally with the pump regulator 39, the oil tank 45 needs to have a larger capacity than the required amount of oil. The space of 5 times or more of the installation space 44 of the oil tank 37 shown in FIG. 10 is required.

  For this reason, conventionally, a method has been adopted in which the flow rate and pressure are electrically controlled by controlling the rotation speed and torque of the hydraulic pump input shaft by an inverter or servo motor using a fixed displacement pump. The method requires high costs, high electrical knowledge, and the like, and there are troublesome problems such as high noise and generation of electrical noise.

The present invention is made to have versatility to the hydraulic control without without impairing the characteristics and usability of the hydraulic system itself in a limited small tank capacity placing different pump regulator of individually controllable characteristics for each actuator It is an object of the present invention to provide a hydraulic source distributed hydraulic unit that uses a multifunctional variable piston pump in an oil immersed state.

In order to achieve the above object, the present invention provides an oil tank in which hydraulic oil is stored, an electric motor disposed on an end surface of the oil tank, and hydraulic oil in the oil tank by the rotational driving force of the electric motor. It is driven and controlled by a hydraulic pump that sucks and discharges, a pump regulator that controls the hydraulic pump, an electromagnetic flow control valve that controls the flow direction, pressure, and flow rate of hydraulic fluid, a shuttle valve, and a hydraulic pump. In a hydraulic source distributed hydraulic unit comprising a hydraulic actuator, a pressure compensated variable piston pump is mounted in an oil tank together with a pump regulator using a pressure compensated variable piston pump as the hydraulic pump, and the pressure compensated variable piston pump The first check valve that can flow in the direction of the electromagnetic flow control valve is disposed in the pipe line between the valve and the electromagnetic flow control valve, and the pump regulator And a secondary-side pilot line through the shuttle valve is connected to the downstream side of the solenoid directional flow control valve of the hydraulic circuit through the second check valve can flow to the secondary side direction of the electromagnetic directional flow control valve, The hydraulic oil discharged from the pressure compensation variable piston pump passes through the first check valve, reaches the second check valve via the shuttle valve from the electromagnetic flow control valve, and before the first check valve. The hydraulic fluid branched and connected to the pump regulator as the primary pilot line and simultaneously branched in front of the first check valve passes through the orifice and then branches in three directions, one of which is the pump regulator The other one reaches the main relief valve, the other one reaches the second check valve, and the secondary pilot valve faces the hydraulic oil that reaches the second check valve via the shuttle valve. Is configured as a conduit, and the electromagnetic directional flow control valve is an orifice in the neutral position, the pump regulator, when the second check valve is configured to communicate with the oil tank, as an electric signal by detecting the pressure in the hydraulic circuit A signal that is input to the arithmetic unit and controls the flow rate with respect to the pressure based on a preset relationship between the pressure and the flow rate is output from the arithmetic unit to the electromagnetic directional flow control valve, and the electromagnetic directional flow control valve is electrically By controlling the external pilot pressure on the secondary side of the pump regulator indirectly, it is possible to add any control characteristics to the pressure compensation variable piston pump without adding separate pump regulators with different control characteristics. This is a configuration of a hydraulic power source distributed type hydraulic unit using a variable piston pump having oil in an oil immersed state. The pressure in the hydraulic circuit is detected by a pressure sensor or a pressure switch.

According to the hydraulic source distributed hydraulic unit using the variable piston pump according to the present invention in an oil-immersed state, an electromagnetic directional flow control valve is installed without touching the hydraulic pump or pump regulator disposed in the oil tank in the oil-immersed state. by indirectly control the external pilot pressure of the pump regulator and electrically controlled flow rate of the hydraulic oil with an arbitrary control characteristic, it is possible to set the pressure. Thus, there is no need for a separate pump regulator for controlling the hydraulic pump . For this reason, it is not necessary to secure a space for storing the overhanging portion of the pump regulator having various control characteristics in the oil tank, so there is no need to use a large-capacity oil tank , and the oil tank can be made compact and saved. In addition to space effect, cost reduction, energy saving effect and noise reduction effect can be obtained.

Further, since there is no need to place a different dedicated pump regulator of the control characteristic for each actuator, preferably in terms of structural and maintenance, yet it eliminates the need to select and adding a dedicated pump regulator for each actuator, There is provided a hydraulic power source distributed type hydraulic unit using a variable piston pump that is multifunctional and versatile without impairing the characteristics and convenience of the hydraulic system itself with a limited small tank capacity in an oil immersed state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a hydraulic source distributed hydraulic unit using a variable piston pump according to the present invention in an oil immersion state will be described below with reference to the drawings. In the present invention, a pressure-compensated variable piston pump is used as a hydraulic pump and is mounted in an oil tank in an oil tank together with the pump regulator, and the secondary pilot line of the pump regulator is connected to the electromagnetic direction flow control valve of the hydraulic circuit. In addition to connecting to the downstream side, the pressure in the hydraulic circuit is detected by a pressure sensor or a pressure switch and input to the arithmetic unit as an electrical signal, and the flow rate is adjusted with respect to the pressure based on the relationship between the preset pressure and flow rate the control signal from the arithmetic unit outputs to the electromagnetic directional flow control valve, by electrically controlling the solenoid directional flow control valve, by controlling the external pilot pressure in the secondary side of the pump regulator, control characteristics without different adding separate pump-regulation other, it is the size which gave any control characteristic to the pressure compensating type variable piston pump It has become a feature.

FIG. 1 is a block diagram of a main part of a hydraulic source distributed hydraulic unit using a variable piston pump according to the present invention in an oil immersion state. As main components, 1 is an oil tank, 11 is a variable piston pump, A pump regulator, 3 is a pressure sensor (or pressure switch), 4 is an electromagnetic flow control valve, 5 is a control panel, and 6 is a sequencer as an arithmetic unit. A pressure-compensated variable piston pump 11 is used as the hydraulic pump , and is mounted in the oil tank 1 together with the pump regulator 2 in an oil-immersed state , and the secondary pilot line of the pump regulator is connected to the electromagnetic flow rate of the hydraulic circuit. Connected to the downstream side of the control valve. A mesh portion 20 represents an installation space of the oil tank 1.

FIG. 2 is a block diagram showing the flow of control. The pressure value 7 detected by the pressure sensor 3 (or pressure switch) is inputted to the sequencer 6 and processed, and the sequencer 6 is set with a preset set value. The opening / closing control of the electromagnetic flow control valve 4 is performed by the output signal 8. 3 is a basic control characteristic diagram showing the relationship between the flow rate and pressure of hydraulic oil discharged from the variable piston pump 11 included in the hydraulic control circuit shown in FIG. 4 , wherein 9 is an electric control characteristic, and 10 is a load sensing characteristic. Is shown.

As described above, the variable piston pump 11 employed in the present invention is a pressure compensation type, and the pump regulator 2 is a remote control type regulator, which is integrated with the variable piston pump 11 and is immersed in the oil tank 1. The storage is installed. The pressure sensor 3 (or pressure switch), shuttle valve 15 and electromagnetic flow control valve 4 are incorporated in the hydraulic control circuit outside the oil tank 1, and the signals detected by the pressure sensor 3 (or pressure switch) during various hydraulic controls. Is read by the sequencer 6 to adjust the pressure and flow rate of the hydraulic oil, thereby obtaining various pump control characteristics.

FIG. 4 is a hydraulic control circuit diagram. First, the main circuit configuration will be described. 11 is a variable piston pump, 12 is an electric motor, 1 is an oil tank, 2 is a pump regulator, 3 is a pressure sensor (or pressure switch), 4 electromagnetic directional flow control valve, the first check valve 13, second check valve 14, 15 is a shuttle valve 18 is a main relief valve 19 is a hydraulic actuator, 21 Ru orifice der. A first check valve 13 that can flow in the direction of the electromagnetic flow control valve is disposed in the pipe line between the variable piston pump 11 and the electromagnetic flow control valve 4, and the secondary pilot pipe of the pump regulator 2 is connected to the shuttle valve 15. Is connected to the downstream side of the electromagnetic flow control valve 4 of the hydraulic circuit via a second check valve 14 that can flow in the secondary direction of the electromagnetic flow control valve 4. Also, hydraulic fluid discharged from the variable piston pump 11 is configured to pass through the first check valve 13 is branched before the first check valve 13, connected to the pump regulator 2 as a primary-side pilot line It is. At the same time, as shown in FIG. 4, the hydraulic oil branched before the first check valve 13 passes through the orifice 21 and then branches in three directions, one for the pump regulator 2 and the other for the other. reaches the main relief valve 18, the remaining one is constructed as a second reached the check valve 14, the secondary-side pilot line to face the working oil that has reached the second check valve 14 through the shuttle valve 15 ing.

According to such a hydraulic control circuit, the pressure-flow rate characteristic of FIG. 3 is determined as an initial setting and stored in the sequencer 6 as a set value or an arithmetic expression. When the electromagnetic flow control valve 4 is neutral during actual operation, when the variable piston pump 11 is driven by the motor 12, the pilot pressure on the secondary side of the pump regulator 2 is communicated with the shuttle valve 15 through the second check valve 14. Therefore, the variable piston pump 11 is unloaded (during non-operation) at the lowest control pressure of the pump regulator 2 because the A and B ports of the electromagnetic flow control valve 4 are opened to the oil tank 1. Therefore, unload operation is possible regardless of the set pressure of the main relief valve 18.

Next, when the electromagnetic flow control valve 4 is excited from the neutral position to the solenoid a or b, the hydraulic oil discharged from the variable piston pump 11 passes through the first check valve 13 and the electromagnetic flow control valve 4. The pressure oil in the P port flows to the excited A or B port, and then the high pressure side is selected by the shuttle valve 15 and the P.P. The second check valve 14 of the P line is reached and is opposed to the pressure of the hydraulic oil from the secondary pilot pipeline of the pump regulator 2. As a result, the balance between the pressure selected by the shuttle valve 15 and the secondary pilot pressure from the pump regulator 2 across the second check valve 14 is maintained within the set pressure of the main relief valve 18. The variable piston pump 11 is On-load operation is performed at a pressure with a constant pressure linked to the P-line pressure.

When the pressure of the hydraulic oil from the secondary pilot line of the pump regulator 2 rises and exceeds the set pressure of the main relief valve 18, The pressure of the P line is released to the oil tank 1 through the main relief valve 18, the differential pressure before and after the orifice 21 reaches the cutoff pressure, the pump regulator 2 is activated, and the variable piston pump 11 is set to the main relief valve 18. On-load cut-off with pressure.

Further, when the balance between the pressure selected by the shuttle valve 15 and the pilot pressure from the pump regulator 2 is lost, and the hydraulic oil from the pilot port tries to pass through the second check valve 14, the difference between the front and rear of the orifice 21. The pressure reaches the cut-off pressure, the pump regulator 2 is activated, and the variable piston pump 11 is cut off. The electromagnetic directional flow control valve 4 has a function of performing directional control and flow control by an external electrical signal, and can set an arbitrary flow rate by the electrical signal. The secondary P.P pressure is detected by the pressure sensor 3 (or pressure switch), and an electric signal having a value set or calculated in advance in the sequencer 6 is output to the electromagnetic flow control valve 4 to arbitrarily determine the pump discharge amount. can do.

  Since the flow rate control of the hydraulic oil is always kept at a constant differential pressure with respect to the secondary side load pressure by the action of the shuttle valve 15 and the pump regulator 2 with respect to the opening degree of the electromagnetic direction flow rate control valve 4, the secondary side load It is possible to control the flow rate with pressure compensation corresponding to the pressure.

FIG. 5 is a cut-off characteristic graph showing the relationship between the discharge amount and discharge pressure of the hydraulic oil by the hydraulic control circuit shown in FIG. 4, and (1) performs the pressure adjustment P1 by the main relief valve 18 to adjust the flow rate q1. the Ri example der made in valve position of the solenoid directional flow control valve 4 (meter-in flow control), exceeds the set pressure of the main relief valve 18 the flow rate q1 is Ru is cut off. (2) The flow rate q1, q2 is adjusted by the electromagnetic direction flow control valve 4, and the switching from q1 to q2 is performed by detecting the discharge pressure P1 with the pressure sensor 3 (or pressure switch), and the detected value is An example of a two-pressure two-flow control type in which an electric signal is input to the sequencer 6 as a signal, an electric signal is sent from the sequencer 6 to the electromagnetic directional flow control valve 4, and the flow rate q2 is controlled in two steps by the electromagnetic directional flow control valve 4 by the signal It is.

(3), at the time of the solenoid valve neutral electromagnetic directional flow control valve 4, a cut-off characteristic graph obtained by adding the ability to automatically unload cutoff (1).

Similarly, (4) is a cut-off characteristic graph in which the function of automatically unloading the electromagnetic directional flow control valve 4 when the solenoid valve is neutral is added to (2), both of which are when the solenoid valve is neutral. As described above, the variable piston pump 11 is unloaded (during non-operation) at the minimum control pressure of the pump regulator 2 and cut off.

FIG. 6 is a front view showing a specific example of a hydraulic source integrated hydraulic unit integrated with a hydraulic actuator using the variable piston pump according to the present invention in an oil immersed state, and FIG. 7 is a left side view of FIG. A base portion of the oil tank 1 is fixed to an upper portion 19, and an electric motor 12 is disposed on an end surface of the oil tank 1. A variable piston pump 11 and a pump regulator 2 are integrally disposed in the oil tank 1 in an oil-immersed state. The front cover 16 at the base of the oil tank 1 has a first check valve 13 and a second check valve. A valve 14 and a main relief valve 18 are arranged, and a shuttle valve 15, a pressure sensor 3 (or a pressure switch), and an electromagnetic direction flow control valve 4 are laminated on the base of the oil tank 1 and the front cover 16 via a manifold 17. Has been placed. Hydraulic oil is stored in the oil tank 1.

8 is a front view showing a specific example of a type in which the hydraulic unit and the hydraulic actuator are mounted separately, and FIG. 9 is a left side view of FIG. 8, except that the hydraulic actuator 19 is provided separately. As in the above example, the variable piston pump 11 and the pump regulator 2 are integrally disposed in the oil tank 1 in an oil-immersed state, and an electric motor 12 is disposed on the end surface of the oil tank 1. The front cover 16 is provided with a first check valve 13, a second check valve 14, and a main relief valve 18, and further, a shuttle valve 15 and a pressure sensor 3 (or the upper part of the front cover 16 are connected via a manifold 17. The pressure switch) and the electromagnetic flow control valve 4 are arranged in a stack. Incidentally, FIG. 8 is an example of a horizontal hydraulic unit, it is also possible to adopt a configuration of a vertical hydraulic unit (the vertical hydraulic unit not shown in the drawing).

As described above in detail, according to the present invention, any pump control characteristic or operation can be performed without touching the hydraulic pump or the pump regulator inside the oil tank by eliminating the need for a separate pump regulator for controlling the hydraulic pump. It is possible to set the oil flow rate and pressure, and without using a large-capacity oil tank, it is possible to reduce the amount of hydraulic oil and save space associated with a compact system, as well as lower costs, energy saving effects, and variable Since the noise reduction effect can be obtained by using the piston pump in an oil-immersed state, the convenience is improved and the maintenance problem does not occur. In particular, it can be widely used as a hydraulic source of an actuator provided in a mechanism operating unit of various industrial machines or the like utilizing an independent and distributed hydraulic system in which a hydraulic source and a control unit are integrated.

  In other words, in a hydraulic source distributed hydraulic unit, it is possible to save space if the hydraulic pump is stored in an oil tank in an oil tank in which hydraulic oil is stored, but a multi-function variable displacement piston pump can be used. In use, various pump regulators for control are indispensable for the hydraulic pump. In this case, a space for storing the hydraulic pump and the pump regulator is provided in the oil tank for the extension of the pump regulator integrated with the hydraulic pump. In the past, it was necessary to select a large-capacity oil tank that exceeded the required amount of hydraulic oil. In addition, since the hydraulic pump in the oil tank is stored in an oil-immersed state, it is not preferable from the viewpoint of structure and maintenance to install a pump regulator having an electric control unit. When setting the various adjusting units, it is troublesome to remove the oil tank each time. In addition, it is necessary to select and add a control unit that matches the required control characteristics each time, and lacks versatility. Therefore, according to the present invention, if the pump regulator having the required control characteristics is not required, and an arbitrary pump control characteristic can be constructed from the outside with an external pilot type single pump regulator, the oil tank can be made compact. A variable piston pump having multifunctional control characteristics can be used in an oil-immersed state while saving space, and the pump regulator can be made versatile.

The principal part block diagram of the hydraulic source dispersion | distribution type hydraulic unit which used the variable piston pump concerning this invention in the oil immersion state. The block diagram which shows the flow of control of this invention. The basic control characteristic figure which shows the relationship between the flow volume and pressure of hydraulic oil. Hydraulic control circuit diagram. The cut-off characteristic graph which shows the relationship between the discharge amount and discharge pressure of the hydraulic fluid by a hydraulic control circuit. The front view which shows the specific example of the hydraulic source dispersion | distribution type hydraulic unit which used the variable piston pump concerning this invention in the oil immersion state. Left side view of FIG. 6. The front view which shows the specific example of the type which mounts | wears with a hydraulic unit and a hydraulic actuator separately. A left side view of FIG. The principal part block diagram of a hydraulic-power source distributed type system. The principal part block diagram which fractured | ruptured a part of the conventional hydraulic power source distributed type system. The principal part block diagram of the conventional hydraulic power source concentration type system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Oil tank 2 ... Pump regulator 3 ... Pressure sensor (or pressure switch)
DESCRIPTION OF SYMBOLS 4 ... Electromagnetic direction flow control valve 5 ... Control board 6 ... Sequencer (as arithmetic unit) 11 ... Variable piston pump 12 ... Electric motor 13 ... First check valve 14 ... Second check valve 15 ... Shuttle valve 16 ... Front cover 17 ... Manifold 18 ... Main relief valve 19 ... Hydraulic actuator 21 ... Orifice

Claims (2)

An oil tank in which hydraulic oil is stored, an electric motor disposed on the end face of the oil tank, a hydraulic pump that sucks and discharges hydraulic oil in the oil tank by the rotational driving force of the electric motor, and a hydraulic pump is controlled Hydraulic source distributed type composed of a pump regulator, a hydraulic circuit incorporating an electromagnetic flow control valve that controls the flow direction, pressure, and flow rate of hydraulic oil and a shuttle valve, and a hydraulic actuator that is driven and controlled by a hydraulic pump In the hydraulic unit,
A pressure-compensated variable piston pump is used as the hydraulic pump, and is installed in an oil tank in an oil tank together with a pump regulator, and an electromagnetic directional flow control is provided in a line between the pressure-compensated variable piston pump and an electromagnetic directional flow control valve. A first check valve that can flow in the valve direction is arranged, and a second check valve that can flow in the secondary direction of the electromagnetic flow control valve through the shuttle pilot valve through the secondary pilot line of the pump regulator. The hydraulic fluid connected to the downstream side of the electromagnetic flow control valve of the hydraulic circuit through the pressure compensation variable piston pump passes through the first check valve and passes through the shuttle valve from the electromagnetic flow control valve. To the second check valve, branch off before the first check valve, and connected to the pump regulator as the primary pilot line, and at the same time the first check valve. The hydraulic fluid branched in front of the valve passes through the orifice and then branched in three directions, one leading to the pump regulator, the other leading to the main relief valve and the remaining one to the second check It is configured as a secondary pilot pipe line that opposes the hydraulic oil that reaches the second check valve via the shuttle valve, and the electromagnetic directional flow control valve has an orifice, a pump regulator, a second valve in the neutral position. The check valve communicates with the oil tank so that the pressure in the hydraulic circuit is detected and input to the arithmetic unit as an electrical signal, and the pressure is determined based on the relationship between the preset pressure and flow rate. a signal for controlling the flow rate output from the arithmetic unit to the electromagnetic directional flow control valve, by electrically controlling the solenoid directional flow control valve, the secondary side of the indirect pump regulator external By controlling the pilot pressure, a variable piston pump can be used in an oil-immersed state, where the pressure-compensating variable piston pump has any control characteristics without adding separate pump regulators with different control characteristics. Used hydraulic power source distributed type hydraulic unit.   2. A hydraulic source distributed hydraulic unit using a variable piston pump according to claim 1, wherein the pressure in the hydraulic circuit is detected by a pressure sensor or a pressure switch.

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