WO2014115527A1

WO2014115527A1 - Hydraulic pressure drive device

Info

Publication number: WO2014115527A1
Application number: PCT/JP2014/000237
Authority: WO
Inventors: 哲弘近藤; 伊藤　誠; 藤山　和人; 浩次坂下
Original assignee: 川崎重工業株式会社
Priority date: 2013-01-25
Filing date: 2014-01-20
Publication date: 2014-07-31
Also published as: CN104364535A; JP2014142032A

Abstract

A hydraulic pressure drive device (1) is provided with direction control valves (26), electromagnetic proportion control valves (42), operating valves (37), and a control device (50). The direction control valves (26), which are provided to each of three actuators (7, 9, 10), supply oil to the actuators (7, 9, 10) at a flow rate corresponding to pilot pressure. The electromagnetic proportion control valves (42), which are provided corresponding to each of the direction control valves (26), provide the direction control valves (26) with output pressure of a pressure corresponding to a received command signal as the pilot pressure. The operating valves (36), which are provided corresponding to each of the electromagnetic proportion control valves (42), output a command pressure corresponding to the manipulated variables of operating levers (37). The control device (50) calculates a command signal corresponding to the command pressure from the operating valves (36) on the basis of output characteristics that are switched according to an actuation condition, and outputs the command signal to the electromagnetic proportion control valves (42) that correspond to the operating valves (36).

Description

Hydraulic drive device

The present invention relates to a hydraulic drive device that is connected to a plurality of actuators and supplies each of the hydraulic pressures discharged from a hydraulic pump to the actuators to drive each of the actuators.

Construction machines such as hydraulic excavators are equipped with a plurality of hydraulic actuators, and by driving the hydraulic actuators, various components such as booms, arms, buckets, swiveling devices, and traveling devices are moved to perform various operations. Can be done. The construction machine is provided with a hydraulic drive device as disclosed in Patent Document 1, for example, in order to drive these hydraulic actuators.

The hydraulic drive device described in Patent Document 1 has a hydraulic pump, and drives the actuator by supplying hydraulic pressure discharged from the hydraulic pump to the actuator. The hydraulic drive device has a control valve (including a flow rate control function and a direction control function), and each control valve is located between the hydraulic pump and the actuator. An operation valve is connected to this control valve. The operation valve is provided with an operation lever, and the operation valve outputs a pilot pressure corresponding to the operation amount of the operation lever to the control valve. The spool of the control valve moves to a position corresponding to the input pilot pressure, and supplies a flow rate corresponding to the position and the load of the actuator to the actuator.

Japanese Patent Laid-Open No. 64-6501

In the hydraulic drive device described in Patent Document 1, an operation signal output from an operation lever as an operation means is input to a controller, and a drive current corresponding to (or processed) an operation amount of the operation lever output from the controller. Is input to the electromagnetic proportional control valve, and the control valve is controlled using the output pressure of the electromagnetic proportional control valve as a hydraulic pilot.

However, disconnection of the operation signal line connected to the controller from the operation lever and connection failure of these connector parts, disconnection of the operation signal line connected from the controller to the electromagnetic proportional control valve, connection failure of these connector parts, or When the controller malfunctions, the actuator cannot be operated even if the operation lever is moved.

Therefore, the present invention provides a hydraulic drive device that enables control of an actuator even when an electronic device related to a pilot operation system including a controller becomes electrically uncontrollable. It is aimed.

The hydraulic drive device of the present invention is a hydraulic drive device that is connected to a plurality of actuators and supplies each of the actuators with the hydraulic fluid discharged from the hydraulic pump to drive each of the actuators. A control valve that is provided every time and that is supplied to at least one of the control valve and the control valve that supplies the actuator with a flow rate of a pressure according to the applied pilot pressure and the load pressure of the actuator, and according to a command signal that is provided A pressure adjusting valve that applies an output pressure to the control valve as the pilot pressure, an operation valve that is provided for each of the pressure adjusting valves and that outputs a command pressure corresponding to an operation amount of the operation lever, and a predetermined operating condition The command signal is calculated based on the output characteristics of the pressure regulating valve to be switched and the command pressure output from the operation valve. A control device that outputs the calculated command signal to the pressure regulating valve corresponding to the operation valve; and the pilot pressure applied to the control valve is changed from the output pressure of the pressure regulating valve to the command pressure of the operation valve. And a switching valve for switching.

According to the present invention, the hydraulic pressure applied to the control valve as the pilot pressure can be automatically switched from the output pressure of the pressure regulating valve to the command pressure of the operation valve by the switching valve. As a result, the pilot pressure applied to the control valve can be controlled from the output pressure of the pressure adjustment valve even when the electronic equipment related to the pilot operation system including the controller becomes electrically uncontrollable and the pressure adjustment valve does not operate. The actuator can be driven by switching to the command pressure of the valve by the switching valve. Furthermore, since the pilot pressure input to the control valve is output based on the output characteristics, the flow rate of the pressure oil flowing through each actuator can be suitably controlled according to the operating conditions by adjusting the contents of the output characteristics. it can.

In the above invention, when the control device satisfies an operating condition including operating at least two or more of the operation levers among the operation levers of the plurality of operation valves, the pressure corresponding to the operated operation valve is selected. It is preferable that the output characteristic of the regulating valve is switched.

According to the above configuration, even if a plurality of operation levers are operated simultaneously and a plurality of actuators are operated simultaneously, each operated operation valve is switched by switching the output characteristics of the pressure regulating valve corresponding to the operated operation valve. The flow rate to each actuator corresponding to can be suitably distributed. That is, it is possible to preferentially distribute the flow rate among the actuators that require a relatively high flow rate among the actuators. Therefore, the operation lever can be operated with the same feeling in both the single operation and the multiple simultaneous operations, and the operability is improved.

In the above invention, the control device, when switching the output characteristics of the pressure regulating valve, the pressure regulating valve so that the output pressure when the operating condition is satisfied is larger than the output pressure when the operating condition is not satisfied. It is preferable to switch the output characteristics.

According to the above configuration, for actuators with a large load where pressure oil does not flow easily, the output characteristics are switched so that the pilot pressure of the corresponding spool is increased, thereby suppressing a decrease in the flow rate flowing through the actuator with a large load. As a result, an increase in the flow rate flowing through the actuator with a small load can be suppressed. Thereby, the deviation of the flow rate distribution due to the simultaneous driving can be suppressed and the flow rate distribution can be suitably performed, and a plurality of actuators can be moved with the same operation feeling as when operated alone.

In the above invention, when the control device switches the output characteristics of the pressure regulating valve so that the flow rate flowing through each actuator corresponds to the command pressure, the control device satisfies the output pressure when the operation condition is not satisfied. It is preferable that the output characteristics of the pressure regulating valve are switched so that the output pressure becomes smaller.

According to the above configuration, for an actuator with a small load in which pressure oil easily flows, the flow rate flowing to the actuator with a small load can be limited by switching the output characteristics so that the pilot pressure of the corresponding spool is small. Thus, the flow rate flowing through the actuator with a large load can be increased. Thereby, the deviation of the flow rate distribution due to the simultaneous driving can be suppressed and the flow rate distribution can be suitably performed, and a plurality of actuators can be moved with the same operation feeling as when operated alone.

In the above invention, the pressure regulating valve is a normally closed electromagnetic proportional control valve, and the switching valve is activated when an output pressure from the pressure regulating valve becomes larger than a predetermined switching pressure. Preferably it is.

According to the above configuration, when a malfunction occurs in the pressure regulating valve and the pressure regulating valve stops operating, the output pressure of the pressure regulating valve becomes lower than the switching pressure. Thereby, the hydraulic pressure given to the control valve as the pilot pressure is automatically switched to the command pressure of the operation valve by the switching valve. In this way, when a malfunction occurs in the pressure control valve and the pressure control valve does not operate, the pilot pressure applied to the control valve is automatically switched to the command pressure of the operation valve, realizing fail-safe can do.

According to the present invention, it is possible to control the actuator even when the electronic control device of the pilot operation system including the controller becomes electrically uncontrollable.

The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings.

It is a side view showing a hydraulic excavator provided with a hydraulic drive unit of an embodiment of the present invention. It is a circuit diagram which shows the hydraulic circuit of the hydraulic drive device of 1st Embodiment. FIG. 3 is an enlarged circuit diagram showing a part of a hydraulic circuit of the hydraulic drive device of FIG. 2. It is a flowchart which shows the control procedure of the hydraulic drive unit of FIG. (A) is a graph which shows the relationship between the command pressure output from an operation valve, and the operation amount of an operation lever, (b) is the relationship between the output pressure output from an electromagnetic proportional control valve, and the operation amount of an operation lever. (C) is a graph which shows the relationship between the opening degree of a direction control valve, and the operation amount of an operation lever. It is a circuit diagram which shows the hydraulic circuit of the hydraulic drive device of 2nd Embodiment.

Hereinafter, the configurations of the

hydraulic drive devices

1 and 1A and the hydraulic excavator 2 including the hydraulic drive devices according to the first and second embodiments of the present invention will be described with reference to the drawings described above. In addition, the concept of the direction in the embodiment is used for convenience of explanation, and regarding the structure of the

hydraulic drive devices

1 and 1A and the hydraulic excavator 2, the arrangement and orientation of the configuration thereof are limited to that direction. It is not a suggestion. Further, the structures of the

hydraulic drive devices

1 and 1A and the excavator 2 described below are only one embodiment of the present invention, and the present invention is not limited to the embodiment and is added within the scope of the invention. Can be deleted, changed.

<First Embodiment>
[Hydraulic excavator]
As shown in FIG. 1, a hydraulic excavator 2 that is a construction machine can perform various operations such as excavation and transportation by an attachment, for example, a bucket 3, attached to a tip portion. The excavator 2 has a traveling device 4 such as a crawler, and a revolving body 5 is placed on the traveling device 4 so as to be capable of turning. The revolving structure 5 is configured to be capable of being swiveled by a revolving motor 10 to be described later, and a driver's seat 5a for a driver to board is formed.

Also, the revolving body 5 is provided with a boom 6 extending upward and obliquely forward from the revolving body 5 so as to be swingable in the vertical direction. A boom cylinder 7 is installed on the boom 6 and the swing body 5, and the boom 6 swings with respect to the swing body 5 by expanding and contracting the boom cylinder 7. At the tip of the swinging boom 6, an arm 8 extending obliquely downward and forward is provided so as to be swingable in the front-rear direction. An arm cylinder 9 is installed on the boom 6 and the arm 8, and the arm 8 swings with respect to the boom 6 by expanding and contracting the arm cylinder 9. Further, a bucket 3 is provided at the tip of the arm 8 so as to be swingable in the front-rear direction. Although not described in detail, the bucket 3 is also provided with a bucket cylinder, and the bucket 3 swings back and forth by expanding and contracting the bucket cylinder.

The hydraulic excavator 2 configured as described above includes a hydraulic drive device 1 that supplies hydraulic pressure to actuators such as a boom cylinder 7, an arm cylinder 9, and a turning motor 10 to drive them, as will be described later. There are various effects. Below, the structure of the hydraulic drive device 1 is demonstrated, referring FIG.2 and FIG.3.

[Hydraulic drive]
The hydraulic drive device 1 is configured by a so-called negative control type hydraulic drive circuit, and includes a hydraulic pump 11. The hydraulic pump 11 is connected to the engine E, and is configured to discharge hydraulic pressure when the engine E is rotationally driven. The hydraulic pump 11 employs a variable displacement hydraulic pump having a swash plate 11a, and discharges hydraulic pressure at a flow rate corresponding to the angle of the swash plate 11a. The discharge port 11 b of the hydraulic pump 11 configured in this way is connected to the main passage 12.

Three

valve units

21, 22, 23 described later are interposed in the main passage 12, and a tank 25 is connected to the downstream side of the

valve units

21, 22, 23 via a throttle 24. In addition, a relief passage 13 is connected to the main passage 12 before and after the restrictor 24 so as to bypass the restrictor 24, and a relief valve 14 is provided in the relief passage 13. Further, a negative control passage 15 is connected to the main passage 12 upstream of the throttle 24 and downstream of the three

valve units

21, 22, and 23. Negative control passage 15 is connected to the servo piston mechanism 16 provided in the hydraulic pump 11, a pressure higher than the tank pressure by diaphragm 24 through the negative control passage 15 is guided to the servo piston mechanism 16 as negative control pressure p _n Yes.

Servo piston mechanism 16 has a servo piston 16a, the servo piston 16a is adapted to move to a position corresponding to the negative control pressure p _n flowing through a negative control passage 15. A swash plate 11a of the hydraulic pump 11 is connected to the servo piston 16a, and the swash plate 11a is tilted at an angle corresponding to the position of the servo piston 16a. Specifically, when the negative control pressure _pn is increased, the swash plate 11a is tilted so as to reduce its angle to decrease the discharge flow rate of the hydraulic pump 11, and when the negative control pressure _pn is decreased, the swash plate 11a is The discharge flow rate of the hydraulic pump 11 is increased by tilting to increase the angle.

Further, a supply passage 17 is connected to the main passage 12, and hydraulic pressure discharged through the supply passage 17 is supplied to the

actuators

7, 9, 10. The supply passage 17 is branched from the main passage 12 downstream of the hydraulic pump 11 and upstream of the three

valve units

21, 22, and 23. The supply passage 17 is also branched into three on the downstream side, and three

valve units

21, 22, and 23 are connected to the

branched passage portions

17a, 17b, and 17c, respectively. The three

valve units

21, 22, and 23 are connected to the tank passage 18, and are connected to the tank 25 via the tank passage 18.

Among these three

valve units

21, 22, and 23, the boom valve unit 21 located on the most upstream side controls the flow direction and flow rate of hydraulic pressure flowing through the boom cylinder 7, and is located on the most downstream side. 23 controls the flow direction and flow rate of the hydraulic pressure flowing through the arm cylinder 9. Further, the turning valve unit 22 located between the two

valve units

21 and 23 controls the flow direction and flow rate of the hydraulic pressure flowing to the turning motor 10 for turning the turning body 5. These three

valve units

21, 22, and 23 have the same configuration and function except that the actuators to be driven are different. Hereinafter, the configuration of the boom valve unit 21 will be described in detail. The configurations of the turning valve unit 22 and the arm valve unit 23 will mainly be described with respect to different points, and the same components will be denoted by the same reference numerals. The description is omitted. Further, regarding the functions of the turning valve unit 22 and the arm valve unit 23, different points will be mainly described, and description of the same functions will be omitted.

[Boom valve unit]
The boom valve unit 21 has a direction control valve (control valve) 26 for controlling the direction of flow of hydraulic pressure and the flow rate thereof. A supply passage 17, a tank passage 18, a first supply / discharge passage 31 and a second supply / discharge passage 32 are connected to the direction control valve 26. The first supply / discharge passage 31 is connected to the head side 7 a of the boom cylinder 7, and the second supply / discharge passage 32 is connected to the rod side 7 b of the boom cylinder 7. The direction control valve 26 has a spool 27, and controls the direction and flow rate of hydraulic pressure in accordance with the position of the spool 27.

More specifically, the spool 27 is configured to be movable from the neutral position M toward the first offset position S1 and the second offset position S2. In the neutral position M, the main passage 12 communicates and is supplied. The passage 17, the tank passage 18, the first supply / discharge passage 31 and the second supply / discharge passage 32 are blocked. Thereby, the supply and discharge of hydraulic pressure to the boom cylinder 7 is stopped, and the movement of the boom 6 is stopped. On the other hand, when the main passage 12 communicates, the negative control pressure _pn increases and the discharge flow rate of the hydraulic pump 11 decreases.

When the spool 27 is moved from the neutral position M toward the first offset position S 1, the supply passage 17 is connected to the first supply / discharge passage 31, and the second supply / discharge passage 32 is connected to the tank passage 18. As a result, hydraulic pressure is supplied to the head side 7a of the boom cylinder 7, the boom cylinder 7 extends, and the boom 6 swings upward. On the other hand, the main passage 12 is squeezed by the spool 27 and is eventually blocked. As a result, the negative control pressure _pn decreases and the discharge flow rate of the hydraulic pump 11 increases.

When the spool 27 is moved from the neutral position M to the second offset position S2, the supply passage 17 is connected to the second supply / discharge passage 32, and the first supply / discharge passage 31 is connected to the tank passage 18. As a result, hydraulic pressure is supplied to the rod side of the boom cylinder 7, the boom cylinder 7 contracts, and the boom 6 swings downward. On the other hand, the main passage 12 is squeezed by the spool 27 and is eventually shut off. As a result, the negative control pressure _pn decreases and the discharge flow rate of the hydraulic pump 11 increases.

Thus, two pilot pressures p ₁ and p ₂ that oppose each other are applied to the spool 27 that switches the connection destination, and the spool 27 moves to a position corresponding to the pilot pressures p ₁ and p _2. ing. That is, the direction control valve 26 supplies the boom cylinder 7 with a hydraulic pressure having a direction and a flow rate corresponding to the pilot pressures p ₁ and p ₂ . These two pilot pressures p ₁ and p ₂ are guided through the first pilot passage 34 and the second pilot passage 35.

In the first pilot passage 34, a first switching valve 41 is provided, and the first switching valve 41 is connected to an operation valve 36 and a first electromagnetic proportional control valve (pressure adjusting valve) 42, respectively. The first switching valve 41 receives the output pressure from the first electromagnetic proportional control valve 42 as a pilot pressure. When the pilot pressure is equal to or lower than a predetermined pressure, the first pilot passage 34 is connected to the operation valve 36, and the pilot pressure is reduced. When the pressure exceeds a predetermined pressure, the connection destination of the first pilot passage 34 is switched from the operation valve 36 to the output pressure from the first electromagnetic proportional control valve 42.

Similarly, a second switching valve 44 is provided in the second pilot passage 35, and the second switching valve 44 is connected to the operation valve 36 and the second electromagnetic proportional control valve (pressure adjusting valve) 45, respectively. . The second switching valve 44 receives the output pressure from the second electromagnetic proportional control valve 45 as a pilot pressure. When the pilot pressure is equal to or lower than a predetermined pressure, the second pilot passage 35 is connected to the operation valve 36, and the pilot pressure is reduced. When the pressure exceeds a predetermined pressure, the connection destination of the second pilot passage 35 is switched from the operation valve 36 to the output pressure from the second electromagnetic proportional control valve 45.

The first switching valve 41 (or the second switching valve 44) operates the hydraulic pressure given to the direction control valve 26 as a pilot pressure from the output pressure of the first electromagnetic proportional control valve 42 (or the second electromagnetic proportional control valve 45). It is possible to switch to the command pressure of the valve 36. As a result, even if the first electromagnetic proportional control valve 42 (or the second electromagnetic proportional control valve 45) malfunctions and does not operate, the pilot pressure applied to the directional control valve 26 is supplied to the first electromagnetic proportional control valve 42 ( Alternatively, the actuator can be driven normally by switching from the output pressure of the second electromagnetic proportional control valve 45) to the command pressure of the operation valve 36 by the first switching valve 41 (or the second switching valve 44).

That is, even when the electronic equipment related to the pilot operation system including the control device 50 to be described later becomes electrically uncontrollable, the actuator can be controlled in the conventional manner. Safe can be realized.

The first electromagnetic proportional control valve 42 and the second electromagnetic proportional control valve 45, which are pressure regulating valves, are so-called normally closed direct proportional control valves. Each of the electromagnetic

proportional control valves

42 and 45 is connected to a pilot pump 47. The pilot pump 47 is connected to the engine E (not shown), and discharges hydraulic pressure when the engine E is driven to rotate. It is configured. Each of the electromagnetic

proportional control valves

42 and 45 adjusts the hydraulic pressure from the pilot pump 47 to the output pressure corresponding to the current flowing therethrough, and outputs it to the respective

solenoid valve passages

43 and 46, respectively.

The output pressure is output to the

solenoid valve passages

43, 46. For example, the first output pressure is output from the first electromagnetic proportional control valve 42 to the first solenoid valve passage 43. When the switching pressure is exceeded, the first switching valve 41 switches the connection destination of the first pilot passage 34 to the first solenoid valve passage 43. Thus, the first output pressure is input to the directional control valve 26 as a first pilot pressure p _1. On the other hand, when the output pressure from the first electromagnetic proportional control valve 42 becomes lower than the switching pressure, the connection destination of the first pilot passage 34 is switched from the first electromagnetic proportional control valve 42 to the operation valve 36 by the first switching valve 41. .

Further, when the second output pressure is output from the second electromagnetic proportional control valve 45 to the second electromagnetic valve passage 46 and the output pressure exceeds the switching pressure of the second switching valve 44, the second switching valve 44 causes the second output pressure to be increased. The connection destination of the pilot passage 35 is switched to the second electromagnetic valve passage 46. Thus, the second output pressure is input to the directional control valve 26 as a second pilot pressure p _2. On the other hand, when the output pressure from the second electromagnetic proportional control valve 45 becomes lower than the switching pressure, the connection destination of the second pilot passage 35 is switched from the second electromagnetic proportional control valve 45 to the operation valve 36 by the second switching valve 44.

The operation valve 36 has an operation lever 37 and outputs hydraulic pressure corresponding to the operation amount of the operation lever 37 in a direction corresponding to the operation direction of the operation lever 37. More specifically, the operation valve 36 is connected to a pilot pump 47 and has a first operation valve passage 48 and a second operation valve passage 49. The first operation valve passage 48 is connected to the first switching valve 41, and the second operation valve passage 49 is connected to the second switching valve 44. The operation valve 36 outputs a first command pressure corresponding to the operation amount of the operation lever 37 to the first operation valve passage 48 when the operation lever 37 is operated in a first direction (for example, forward). Is operated in the second direction (for example, rearward), the second command pressure corresponding to the operation amount of the operation lever 37 is output to the second operation valve passage 49.

The first operation valve passage 48 is provided with a first pressure sensor PS1 for detecting the first command pressure output thereto. The second operating valve passage 49 is provided with a second pressure sensor PS2 for detecting the second command pressure output thereto. These two pressure sensors PS1 and PS2 are electrically connected to the control device 50 together with the two electromagnetic

proportional control valves

42 and 45 described above.

The control device 50 is configured to acquire the first command pressure and the second command pressure from the two pressure sensors PS1 and PS2, respectively, and based on the acquired first command pressure and second command pressure, An operation state (operation amount and operation direction) is detected. In addition, the control device 50 allows current (command signal) to flow through the two electromagnetic

proportional control valves

42 and 45, and the output command signal includes a predetermined output characteristic and an operation amount of the operation lever 37. To be determined. A plurality of output characteristics of the electromagnetic

proportional control valves

42 and 45 for determining the command signal are stored in the controller 50 for each of the electromagnetic proportional control valves 42 and 45 (for example, a first output characteristic to a third output described later). Characteristic). The control device 50 determines whether or not the operation state of the hydraulic drive device 1 satisfies a predetermined operation condition, and determines which output characteristic to use based on the determination result. The details of the method for determining the characteristics will be described later. The operating conditions include, for example, operating states of the other valve units 22 and 23 (that is, operating states of the other operating lever 37), the rotational speed of the engine E, and the oil temperature. And the rotation speed and oil temperature of the engine E are detected by a sensor (not shown).

In the boom valve unit 21 configured as described above, when the operation lever 37 is operated in the first direction and the first command pressure is output from the operation valve 36, the first pressure sensor PS1 reduces the first command pressure. The detected first command pressure is sent to the control device 50. Then, the control device 50 determines which operating condition the operating state of the hydraulic drive device 1 satisfies, and selects an output characteristic used for calculating the command signal based on the determination result. Thereafter, the control device 50 calculates a command signal corresponding to the first command pressure based on the selected output characteristic. The calculated command signal is sent to the first electromagnetic proportional control valve 42 by the control device 50, and the first output pressure of the pressure corresponding to the command signal is sent to the first electromagnetic valve passage 43 by the first electromagnetic proportional control valve 42. Is output. When the pressure in the passage 43 becomes higher than a predetermined switching pressure of the first switching valve, the connection destination of the first pilot passage 34 is changed from the first operating valve passage 48 to the first electromagnetic valve passage by the first switching valve 41. is switched to 43, the first output pressure is input to the directional control valve 26 as a first pilot pressure p _1. Accordingly, it pushed the spool 27 toward the first offset position S1 by the first pilot pressure p _1. Thereby, it guide | induces to the head side 7a of the cylinder 7 for booms, and the boom 6 is lifted upwards.

On the other hand, when the operation lever 37 is operated in the second direction and the second command pressure is output from the operation valve 36, the second pressure sensor PS2 detects the second command pressure, and the detected second command pressure is the control device. 50. Then, the control device 50 determines which operating condition the operating state of the hydraulic drive device 1 satisfies, and selects an output characteristic used for calculating the command signal based on the determination result. Thereafter, the control device 50 calculates a command signal corresponding to the second command pressure based on the selected output characteristic. The calculated command signal is caused to flow to the second electromagnetic proportional control valve 45 by the control device 50, and a second output pressure corresponding to the command signal is output to the second electromagnetic valve passage 46 by the second electromagnetic proportional control valve 45. Is done. When the pressure of the passage 46 becomes higher than a predetermined switching pressure of the second switching valve, the connection point of the second pilot passage 35 is changed from the second operation valve passage 49 to the second electromagnetic valve passage by the second switching valve 44. is switched to 46, the second output pressure is input to the directional control valve 26 as a second pilot pressure p _2. Accordingly, it pushed the spool 27 towards the second pilot pressure p ₂ by the second offset position S2. Thereby, it guide | induces to the rod side 7b of the cylinder 7 for booms, and the boom 6 is lowered | hung below.

In the control device 50 that controls in this way, the operating state of the hydraulic drive device 1 is detected by various sensors, and based on the detection result, it is determined which operating condition is satisfied, and output characteristics that are used. Is selected. For example, when the control device 50 determines that the operating condition that the oil temperature detected by the oil temperature sensor is equal to or higher than a predetermined first predetermined temperature is satisfied, the control device 50 supplies hydraulic pressure to the boom cylinder 7. The output characteristic that makes it difficult (that is, the output characteristic that lowers the output pressure by reducing the current flowing through the electromagnetic

proportional control valves

42 and 45 with respect to the command pressure) is selected. As a result, the flow rate of the hydraulic pressure flowing through the boom cylinder 7 can be regulated, and the impact caused by the excessive supply by suppressing the excessive supply to the boom cylinder 7 at the start of the operation of the boom 6 in a high temperature environment where the viscosity is low. Can be relaxed.

Conversely, when the control device 50 determines that the operating condition that the oil temperature detected by the oil temperature sensor is equal to or higher than another second predetermined temperature (<first predetermined temperature) is not satisfied, the control device 50 An output characteristic that facilitates the flow of hydraulic pressure to the boom cylinder 7 (that is, an output characteristic that increases the current flow through the electromagnetic

proportional control valves

42 and 45 with respect to the command pressure to increase the output pressure) is selected. Thereby, the flow rate of the oil flowing into the boom cylinder 7 can be increased, and the operation of the boom 6 caused by the supply shortage is suppressed by suppressing the supply of the boom cylinder 7 under the low temperature environment where the viscosity is high. You can eliminate the sluggishness.

Similarly, the control device 50 selects an output characteristic that reduces the shock at the start of operation by regulating the flow rate of the hydraulic pressure flowing through the boom cylinder 7 when the rotational speed of the engine E is the operating condition and the rotational speed is high. The control device 50 selects an output characteristic that makes it easy to flow hydraulic pressure from the boom valve unit 21 to the boom cylinder 7 when the rotational speed is small, and eliminates the slack at the start of the operation of the boom 6. May be. Moreover, the load of the boom 6 can be set as an operating condition, and the flow rate can be regulated or allowed according to the load.

In the boom valve unit 21 that operates the boom 6 in this way, the spool 27 moves to a position corresponding to the command signal. Therefore, by changing the contents of the output characteristics, it is possible to suppress fluctuations in the flow rate flowing through the boom cylinder 7 according to the operating conditions. Thereby, the drive speed of the boom cylinder 7 with respect to the operation amount of the operation lever 37 can be suppressed according to the operating conditions.

Conventionally, in order to change the drive speed of the boom cylinder 7 with respect to the operation amount of the operation lever 37, the spool 27 is tuned to adjust the opening degree of the spool 27 or to resist the pilot pressures p ₁ and p ₂ , respectively. It is necessary to change the

springs

27a, 27b provided in the. On the other hand, since the drive speed of the boom cylinder 7 with respect to the operation amount of the operation lever 37 can be changed by changing the content of the output characteristics with the control device 50, the boom cylinder with respect to the operation amount of the operation lever 37 can be changed. 7 can be easily adjusted.

Further, since the boom valve unit 21 employs the normally closed electromagnetic

proportional control valves

42 and 45, an electric system malfunction or the like (including a malfunction of the controller) occurs, causing them to operate. When it disappears, the output pressure is not output to the

solenoid valve passages

43 and 46. Then, even after the operation lever 37 is operated, the connection destinations of the

pilot passages

34 and 35 are not switched to the

electromagnetic valve passages

43 and 46 but remain connected to the

operation valve passages

48 and 49. Therefore, when the electronic devices related to the pilot operation system including the control device 50 become electrically uncontrollable and the electromagnetic

proportional control valves

42 and 45 do not operate, the command pressure output from the operation valve 36 is directional controlled. The valve 26 is provided. Therefore, the boom cylinder 7 can be operated even if the electromagnetic

proportional control valves

42 and 45 are not operated, and failsafe can be realized in the boom valve unit 21.

[Swivel valve unit]
In the turning valve unit 22, the first supply / discharge passage 31 and the second supply / discharge passage 32 are connected to the turning motor 10. The turning motor 10 is a so-called hydraulic motor, and has two

ports

10a and 10b. The turning motor 10 rotates forward and backward according to the

ports

10a and 10b to which hydraulic pressure is supplied. The first supply / discharge passage 31 is connected to the first port 10a and the second port 10b is connected to the second port 10b. A second supply / discharge passage 32 is connected.

In the turning valve unit 22 configured as described above, when the spool 27 is located at the neutral position M, the supply and discharge of the hydraulic pressure to the turning motor 10 is stopped and the turning of the turning body 5 is stopped. When the spool 27 is located at the first offset position S1, the turning motor 10 rotates forward and the turning body 5 turns. When the spool 27 is located at the second offset position S2, the turning motor 10 rotates reversely and the turning body 5 rotates. Turns.

In the turning valve unit 22, the third pressure sensor PS3 for detecting the first command pressure is provided in the first operation valve passage 48, and the fourth pressure sensor PS4 for detecting the second command pressure is the second operation valve. The passage 49 is provided. The third pressure sensor PS3 and the fourth pressure sensor PS4 are electrically connected to the control device 50, and the control device 50 receives the first command pressure and the second command pressure from the third pressure sensor PS3 and the fourth pressure sensor PS4. To get.

In the swivel valve unit 22 configured in this way, first, output characteristics corresponding to the operating conditions satisfied by the control device 50 are selected. The operating conditions and output characteristics are set separately for each

valve unit

21, 22, 23 and for each electromagnetic

proportional control valve

42, 45. Then, based on the selected output characteristics, a command signal corresponding to the first command pressure or the second command pressure sent from the third pressure sensor PS3 and the fourth pressure sensor PS4 is calculated. For example, when the operation lever 37 is operated in the first direction, the control device 50 causes a command signal corresponding to the output pressure to flow through the first electromagnetic proportional control valve 42 based on the selected output characteristic. As a result, the spool 27 moves to the first offset position S <b> 1, and a hydraulic pressure having a flow rate corresponding to the command signal is supplied to the first port 10 a of the turning motor 10. On the other hand, when the operation lever 37 is operated in the second direction, the control device 50 causes a command signal corresponding to the output pressure to flow through the second electromagnetic proportional control valve 45 based on the selected output characteristic. As a result, the spool 27 moves to the second offset position S2, and a hydraulic pressure having a flow rate corresponding to the command signal is supplied to the second port 10b.

As described above, in the turning valve unit 22, the command signal is calculated based on the output characteristics selected according to the operating state of the hydraulic drive device 1, so that the turning motor 10 is the same as the boom valve unit 21. It is possible to reduce impact and shaking at the start of the operation. Further, in the turning valve unit 22, a large amount of high-pressure oil is prevented from flowing into the turning motor 10 by selecting an output characteristic so that the opening degree of the direction control valve 26 is reduced when the operation of the turning motor 10 is started. Energy saving can be achieved.

[Valve unit for arm]
In the arm valve unit 23, the first supply / discharge passage 31 and the second supply / discharge passage 32 are connected to the head side 9a and the rod side 9b of the arm cylinder 9, respectively. The arm cylinder 9 expands when hydraulic pressure is supplied to the head side 9a, and contracts when hydraulic pressure is supplied to the rod side 9b.

Thus, the arm valve unit 23 connected to the arm cylinder 9 stops the movement of the arm 8 by stopping the supply and discharge of the hydraulic pressure to the arm cylinder 9 when the spool 27 is located at the neutral position M. It has become. Further, when the spool 27 is located at the first offset position S1, the arm valve unit 23 supplies hydraulic pressure to the head side 9a of the arm cylinder 9 to swing the arm 8 rearward (pulling side), so that the spool 27 Is positioned at the second offset position S2, the hydraulic pressure is supplied to the rod side 9b of the arm cylinder 9 to swing the arm 8 forward (pushing side).

In the arm valve unit 23, the fifth pressure sensor PS5 for detecting the first command pressure is provided in the first operation valve passage 48, and the sixth pressure sensor PS6 for detecting the second command pressure is the second operation valve. The passage 49 is provided. The fifth pressure sensor PS5 and the sixth pressure sensor PS6 are electrically connected to the control device 50, and the control device 50 receives the first command pressure and the second command pressure from the fifth pressure sensor PS5 and the sixth pressure sensor PS6. To get.

In the arm valve unit 23 configured as described above, first, output characteristics corresponding to the operating conditions satisfied by the control device 50 are selected. Then, the control device 50 calculates a command signal based on the first command pressure or the second command pressure sent from the fifth pressure sensor PS5 and the sixth pressure sensor PS6 based on the selected output characteristic. For example, when the operation lever 37 is operated in the first direction, the control device 50 causes a command signal corresponding to the output pressure to flow through the first electromagnetic proportional control valve 42 based on the selected output characteristic. As a result, the spool 27 moves in the direction of the first offset position S1, and a hydraulic pressure having a flow rate corresponding to the command signal and the load pressure is supplied to the head side 9a of the arm cylinder 9. On the other hand, when the operation lever 37 is operated in the second direction, the control device 50 causes a command signal corresponding to the output pressure to flow through the second electromagnetic proportional control valve 45 based on the selected output characteristic. As a result, the spool 27 moves in the direction of the second offset position S2, and a hydraulic pressure having a flow rate corresponding to the command signal and the load pressure is supplied to the rod side 9b of the arm cylinder 9.

Thus, since the arm valve unit 23 calculates the command signal based on the output characteristics selected according to the operating state of the hydraulic drive device 1, the arm cylinder 9 is similar to the boom valve unit 21. It is possible to reduce impact and shaking at the start of the operation.

[Hydraulic drive function]
In the hydraulic drive device 1, when the operation lever 37 of each

valve unit

21, 22, 23 is operated as described above, an output pressure corresponding to the operation direction is output from the operation valve 36. When the output pressure output is detected by any of the pressure sensors PS1 to PS6, the control device 50 sends a command signal to the electromagnetic

proportional control valves

42 and 45 corresponding to the operated operation valve 36 or the operation lever 37. Therefore, the output characteristics of the corresponding electromagnetic

proportional control valves

42 and 45 are selected according to the operating conditions of the hydraulic drive device 1, and the command signal is calculated based on the selected output characteristics. When the operation lever 37 is operated independently, the control device 50 selects the first output characteristic that is basically a reference except when the operation is started as described above, and based on the first output characteristic. A command signal corresponding to the operation amount of the operation lever 37 is supplied to the electromagnetic

proportional control valves

42 and 45. As a result, an output pressure corresponding to the command signal is output from the electromagnetic

proportional control valves

42 and 45, and the

actuators

7, 9, and 10 are driven according to the operation amount of the operation lever 37 corresponding thereto and the load pressure of each actuator. It can be moved with.

On the other hand, when two or more operation levers 37 are operated at the same time, they function as follows. When the command pressure is detected by two or more of the plurality of pressure sensors PS1 to PS6, the control device 50 selects the output characteristics of the electromagnetic

proportional control valves

42 and 45 that output the output pressure. Here, since the control device 50 determines that the operation condition that two or more operation levers 37 are simultaneously operated is satisfied, an output characteristic is selected based on the determination result, and each electromagnetic proportional control valve 42, A command signal to be output to 45 is calculated.

The output characteristics to be selected will be described in more detail. Among the

valve units

21, 22, and 23 in which the operation lever 37 is simultaneously operated, the

actuators

7, 9, and 10 that are driven by the

actuators

7, 9, and 10 have a large load. A second output characteristic with a command signal output to the

control valves

42 and 45 greater than the first output characteristic is selected. When this second output characteristic is selected, the opening degree of the directional control valve 26 becomes larger than in the case of the first output characteristic, and the flow rate of oil flowing from the directional control valve 26 to the

actuators

7, 9, 10 increases. The flow rate flowing through the

other actuators

7, 9, 10 decreases.

Contrary to the above, among the

valve units

21, 22, and 23 in which the operation lever 37 is simultaneously operated, the

actuators

7, 9, and 10 that are driven by the

actuators

7, 9, and 10 have a small load. The second output characteristic may be selected such that the command signal output to 45 is larger than the first output characteristic.

Therefore, the correspondence relationship between the operation speed of the

actuators

7, 9, and 10 and the operation amount of the operation lever 37 differs depending on whether two or more operation levers 37 are operated simultaneously.

As described above, by changing the output characteristics according to the operation state of the operation lever 37, the flow rate of the pressure oil flowing through the

actuators

7, 9, 10 can be controlled according to the output characteristics of the electromagnetic proportional control valves. it can. Further, by adjusting the contents of the output characteristics, the flow distribution of the pressure oil flowing through the

actuators

7, 9, 10 can be adjusted. In the present embodiment, the output characteristic of each electromagnetic proportional control valve corresponding to the operated operation lever 37 is appropriately selected regardless of whether the operation lever 37 is operated individually or simultaneously. .

In the following, the case where the operation lever 37 of the boom valve unit 21 is operated to raise the boom 6 will be described as an example with reference to the flowchart of FIG. 4 and the graphs of FIGS. explain. 5A to 5C, the vertical axis represents the first command pressure of the operation valve 36 of the boom valve unit 21, the first output pressure of the first electromagnetic proportional control valve of the boom valve unit 21, and The opening area of the direction control valve 26 of the boom valve unit 21 is shown, and the horizontal axis shows the operation amount of the operation lever 37 of the boom valve unit 21.

When the operation lever 37 of the boom valve unit 21 is operated in the first direction and the first command pressure is output from the operation valve 36, the control device 50 detects that the boom 6 is raised and the boom is raised. A process is performed and it transfers to step ST1. In step ST1, the control device 50 determines whether or not the operation lever 37 of the turning valve unit 22 is operated. That is, the control device 50 determines whether or not the output pressures detected by the third pressure sensor PS3 and the fourth pressure sensor PS4 are equal to or lower than a predetermined pressure (for example, 0.05 MPa). When it is determined that the output pressures detected by the third pressure sensor PS3 and the fourth pressure sensor PS4 are both equal to or lower than the predetermined pressure, the process proceeds to step ST2. In step ST2, whether the operation lever 37 of the arm valve unit 23 is operated in the first direction, that is, whether the fifth pressure sensor PS5 and the sixth pressure sensor PS6 are equal to or lower than a predetermined pressure (for example, 0.05 MPa). Determine whether. If it is determined that the output pressures detected by the fifth pressure sensor PS5 and the sixth pressure sensor PS6 are equal to or lower than the predetermined pressure, the process proceeds to step ST3.

The control device 50 executes control when it is determined that the operation lever 37 of the boom valve unit 21 is operated alone by moving to step ST3. In step ST3, first, the control device 50 selects the first output characteristic. This output pressure characteristic is the same as the output pressure (command pressure) of the operation valve. A command signal corresponding to the first command pressure detected by the first pressure sensor PS1 is calculated based on the first output characteristic. When calculated, the process proceeds to step ST4.

In step ST4, the command signal calculated by the control device 50 is supplied to the first electromagnetic proportional control valve 42 of the boom valve unit 21. Then, the operation of the operation lever 37 from the first electromagnetic proportional control valve 42 with respect to the output pressure (command pressure) of the operation valve 36 that monotonously increases with respect to the operation amount of the operation lever 37 as shown in FIG. A first output pressure as shown by the solid line in FIG. By outputting such a first output pressure, the opening degree of the direction control valve 26 of the boom valve unit 21 changes as indicated by the solid line in FIG. 5C with respect to the operation amount of the operation lever 37. . As a result, the hydraulic pressure at a flow rate corresponding to the operation amount of the operation lever 37 and the load pressure (pressure on the head side 7a of the boom cylinder) is guided to the head side 7a of the boom cylinder 7 at a driving speed corresponding to the flow rate. The boom 6 operates.

On the other hand, if it is determined in step ST2 that the fifth pressure sensor PS5 and the sixth pressure sensor PS6 exceed the predetermined pressure, the process proceeds to step ST5. The control device 50 executes control when it is determined in step ST5 that the operation levers 37 of the boom valve unit 21 and the arm valve unit 23 are simultaneously operated. In step ST5, first, the control device 50 selects the second output characteristic for the first electromagnetic proportional control valve 42 of the boom valve unit 21. This second output characteristic has the same characteristic as the command pressure of the operation valve in a range where the output pressure is lower than the switching pressure of the switching valve. The control device 50 calculates a command signal corresponding to the first command pressure detected by the first pressure sensor PS1 based on the second output characteristic. When calculated, the process proceeds to step ST4.

In step ST4, the control device 50 causes the calculated command signal to flow through the first electromagnetic proportional control valve 42 of the boom valve unit 21. If it does so, with respect to the operation amount of the operation lever 37 from the 1st electromagnetic proportional control valve 42 with respect to the output pressure of the operation valve 36 which monotonously increases like FIG. A first output pressure as indicated by the alternate long and short dash line in FIG. By outputting such first output pressure, the opening degree of the directional control valve 26 of the boom valve unit 21 changes as indicated by the one-dot chain line in FIG. To do. That is, when the opening degree of the direction control valve 26 of the boom valve unit 21 is independently operated (the solid line in FIG. 5C), the opening of the direction control valve 26 of the boom valve unit 21 is greatly opened.

Since the boom cylinder 7 has a larger load than the arm cylinder 9, if the two operation levers 37 are operated simultaneously, the hydraulic pressure does not easily flow to the boom cylinder 7. By increasing the opening of the direction control valve 26 of the boom valve unit 21, it is possible to suppress a decrease in the flow rate of the hydraulic pressure flowing through the boom cylinder 7. Then, by correcting the command signal in the control device 50, even if the two operation levers 37 are operated simultaneously, the boom cylinder 7 and the arm cylinder 9 are driven more faithfully by the operation amount of the corresponding operation lever 37. It can be driven at speed.

The command signal calculated based on the first output characteristic flows through the electromagnetic

proportional control valves

42 and 45 of the arm valve unit 23, and the electromagnetic

proportional control valves

42 and 45 of the arm valve unit 23, for example, FIG. An output pressure as shown by the solid line in (b) is output. However, the present invention is not limited to the case where the first output characteristic is selected in this way, and the control device 50 selects the third output characteristic described later to reduce the flow rate of the oil flowing through the arm valve unit 23, and this third output characteristic is selected. The command signal may be calculated based on the output characteristics.

If it is determined in step ST1 that one of the third pressure sensor PS3 and the fourth pressure sensor PS4 exceeds the predetermined pressure, the process proceeds to step ST6. The control device 50 executes control when it is determined that the operation levers 37 of the boom valve unit 21 and the turning valve unit 22 are simultaneously operated by moving to step ST6. In step ST6, first, the control device 50 selects the third output characteristic for the first electromagnetic proportional control valve 42 of the boom valve unit 21. This third output characteristic also has the same characteristic as the command pressure of the operation valve in a range where the output pressure is lower than the switching pressure of the switching valve. A command signal corresponding to the first command pressure detected by the first pressure sensor PS1 is calculated based on the third output characteristic. Once calculated, the process proceeds to step ST4.

In step ST4, the control device 50 causes the calculated command signal to flow through the first electromagnetic proportional control valve 42 of the boom valve unit 21. If it does so, with respect to the operation amount of the operation lever 37 from the 1st electromagnetic proportional control valve 42 with respect to the output pressure of the operation valve 36 which monotonously increases like FIG. An output pressure as indicated by a two-dot chain line in FIG. 5B is output. By outputting such output pressure, the opening degree of the directional control valve 26 of the boom valve unit 21 changes as shown by a two-dot chain line in FIG. 5C with respect to the operation amount of the operation lever 37. . That is, when the opening degree of the direction control valve 26 of the boom valve unit 21 is independently operated (solid line in FIG. 5C), the opening of the direction control valve 26 of the boom valve unit 21 is narrowed.

Since the boom cylinder 7 has a smaller load than the turning motor 10, the hydraulic pressure flows preferentially to the boom cylinder 7 when the two operation levers 37 are operated simultaneously. However, the direction control valve 26 of the boom valve unit 21 By restricting the opening, an increase in the flow rate of the oil flowing into the boom cylinder 7 can be suppressed. Then, by correcting the command signal in the control device 50, even when the two operation levers 27 are operated simultaneously, the boom cylinder 7 and the turning motor 10 are driven more faithfully by the operation amounts of the corresponding operation levers 37. It can be driven at speed.

A command signal calculated based on the first output characteristic flows through the electromagnetic

proportional control valves

42 and 45 of the turning valve unit 22, and the electromagnetic

proportional control valves

42 and 45 of the turning valve unit 22, for example, FIG. An output pressure as shown by the solid line in (b) is output. However, the present invention is not limited to the case where the first output characteristic is selected in this way, and the control device 50 selects the second output characteristic in order to increase the flow rate of the oil flowing through the turning valve unit 22, and this second output characteristic. The command signal may be calculated based on the above.

In the hydraulic drive device 1 that performs such an operation, the output characteristics of the command signal are switched in accordance with the operating state of the hydraulic drive device 1, so that the flow rate of oil that is extremely faithful to the operation amount of the operation lever 37 is supplied to each actuator 7. , 9, 10 can be supplied. As a result, the relief valve of the turning motor 10 is actuated to reduce energy consumption released as heat or the like, and energy saving of the hydraulic drive device 1 can be achieved.

Further, in the hydraulic drive device 1, as described above, the drive speed of the

actuators

7, 9, 10 with respect to the operation amount of the operation lever 37 can be changed by adjusting the content of the output characteristics. Therefore, it is sufficient to perform tuning (that is, setting the optimum opening area) to a minimum as in the case of adopting hydraulic pilot control (control using the command pressure of the operation valve as a pilot signal for the control valve). 1 development man-hours can be shortened.

Second Embodiment
The hydraulic drive device 1A of the second embodiment is similar in configuration to the hydraulic drive device 1 of the first embodiment. In the following, the configuration of the hydraulic drive device 1A of the second embodiment will be described mainly with respect to differences from the hydraulic drive device 1 of the first embodiment, and the same components will be denoted by the same reference numerals and the description thereof will be given. May be omitted.

The hydraulic drive device 1 </ b> A is configured by a positive control hydraulic drive circuit, and the main passage 12 </ b> A is directly connected to the tank 25 without the throttle 24. In the hydraulic drive apparatus 1A, a pilot pump 47 is connected to the servo piston mechanism 16 via a positive control passage 15A, and an electromagnetic valve 19 is interposed in the positive control passage 15A.

Solenoid valve 19 is an electromagnetic control valve of normally closed type, and outputs under reduced pressure the hydraulic pressure discharged from the pilot pump 47 to a pressure corresponding to the current flowing through the solenoid valve 19 as the lever-regulated, pump control pressure p _p . The lever-regulated, pump control pressure p _p which is output in this way is guided to the servo piston mechanism 16, servo piston 16a is adapted to move to a position corresponding to the positive control pressure p _p. Thus, the swash plate 11a is tilted to an angle corresponding to the lever-regulated, pump control pressure p _p.

The electromagnetic valve 19 configured as described above is connected to the control device 50, and the control device 50 determines the current to flow through the electromagnetic valve 19 based on the output pressure obtained from each of the pressure sensors PS1 to PS6. . For example, the control device 50 causes a current corresponding to the acquired output pressure, that is, a large current to flow to the solenoid valve 19 when the output pressure is large, and a small current corresponding to the solenoid valve 19 to flow when the output pressure is small. It has become. In other words, the control device 50 causes the current corresponding to the operation amount of the operation lever 37 to flow through the solenoid valve 19, and causes the hydraulic pump 11 to output oil having a flow rate corresponding to the operation amount.

The control device 50 also adjusts the current flowing through the electromagnetic valve 19 in accordance with the number of pressure sensors PS1 to PS6 that detect the output pressure, and when the output pressure is simultaneously detected by the plurality of pressure sensors PS1 to PS6. A large current corresponding to the number is supplied to the electromagnetic valve 19. That is, the control device 50 causes the current corresponding to the number of the operation levers 37 operated simultaneously to flow through the electromagnetic valve 19, and causes the hydraulic pump 11 to output oil having a flow rate corresponding to the operation amount. However, the maximum value of the current flowing through the solenoid valve 19 is determined in advance, and the above control is executed within a range not exceeding the maximum value.

The hydraulic drive device 1A configured as described above has the same operational effects as the hydraulic drive device 1 of the first embodiment, except for the operational effects due to the application of a positive control hydraulic drive circuit.

<Other forms>
In the

hydraulic drive devices

1 and 1A, the control device 50 switches the output characteristic for mainly calculating the command signal to be sent to the first electromagnetic proportional control valve 42 of the boom valve unit 21, but the turning valve unit 22 that operates simultaneously. Or you may make it switch the control apparatus 50 the output characteristic which calculates the command signal sent to the electromagnetic

proportional control valves

42 and 45 of the valve unit 23 for arms. At this time, the output characteristic for calculating the command signal to be sent to the first electromagnetic proportional control valve 42 may not be switched from the first output characteristic regardless of the operating state of the hydraulic drive device 1.

The actuator driven by the

hydraulic drive devices

1 and 1A is not limited to the one described above, and may be a bucket cylinder, a steering cylinder, or a travel drive motor. Further, the hydraulic pump 11 is not necessarily a variable displacement pump, and may be a fixed displacement pump or an oblique axis pump. Further, the hydraulic pump 11 is rotationally driven not only by the engine but also by an electric motor. Furthermore, the electromagnetic

proportional control valves

42 and 45 are preferably normally closed, but may be normally open electromagnetic proportional control valves. Further, the pressure liquid used as the operating pressure is not limited to oil, and may be water or other liquid.

From the above description, many modifications and other embodiments of the present invention are apparent to persons skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

DESCRIPTION OF

SYMBOLS

1,1A Hydraulic drive device 2 Hydraulic excavator 7 Boom cylinder 9 Arm cylinder 10 Turning motor 11 Hydraulic pump 26 Direction control valve (control valve)
27 Spool 36 Operating valve 37 Operating lever 41 First switching valve 42 First electromagnetic proportional control valve (pressure adjusting valve)
44 Second switching valve 45 Second electromagnetic proportional control valve (pressure regulating valve)
50 Control device

Claims

A hydraulic pressure driving device connected to a plurality of actuators and supplying each of the hydraulic fluid discharged from a hydraulic pump to the actuators to drive each of the actuators,
A control valve that is provided for each actuator and supplies the actuator with a flow rate of a pressure fluid corresponding to a given pilot pressure and a load pressure of the actuator;
A pressure regulating valve that is provided in at least one of the control valves and applies an output pressure corresponding to a given command signal to the control valve as the pilot pressure;
An operation valve that is provided for each pressure adjusting valve and outputs a command pressure according to the operation amount of the operation lever;
The command signal is calculated based on an output characteristic of the pressure regulating valve that is switched in accordance with a predetermined operating condition and the command pressure output from the operation valve, and the calculated command signal corresponds to the operation valve. A control device for outputting to the pressure regulating valve;
A hydraulic pressure drive device comprising: a switching valve that switches the pilot pressure applied to the control valve from the output pressure of the pressure adjustment valve to the command pressure of the operation valve.
The control device outputs an output of the pressure adjusting valve corresponding to the operated operation valve when an operation condition including operation of at least two or more of the operation levers among the operation levers of the plurality of operation valves is satisfied. 2. The hydraulic drive device according to claim 1, wherein the characteristics are switched.
When switching the output characteristic of the pressure regulating valve, the control device sets the output characteristic of the pressure regulating valve so that the output pressure when the operating condition is satisfied is larger than the output pressure when the operating condition is not satisfied. The hydraulic drive device according to claim 1 or 2, wherein the hydraulic drive device is adapted to be switched.
When switching the output characteristic of the pressure regulating valve, the control device switches the output characteristic of the pressure regulating valve so that the output pressure when the operating condition is satisfied is smaller than the output pressure when the operating condition is not satisfied. The hydraulic drive device according to claim 1, wherein the hydraulic drive device is configured as described above.
The pressure regulating valve is a normally closed electromagnetic proportional control valve,
The hydraulic pressure driving device according to claim 3 or 4, wherein the switching valve is activated when an output pressure from the pressure regulating valve becomes smaller than a predetermined switching pressure.