Patent Publication Number: US-10760245-B2

Title: Drive control device for construction machine

Description:
TECHNICAL FIELD 
     The present invention relates to a drive control device for a construction machine suitable for use in a construction machine such as a hydraulic excavator and the like, for example. 
     BACKGROUND ART 
     For example, a construction machine such as a hydraulic excavator can perform excavation by a working mechanism (front) composed of a boom, an arm, a bucket and the like, travel of a machine by a lower traveling structure, revolution of an upper revolving structure and the like. Therefore, the hydraulic excavator is provided with an operating lever that is operated by an operator to perform the excavation, the travel, the revolution and the like, a plurality of hydraulic actuators for performing these movements of the excavation, the travel, the revolution and the like, a main pump that delivers pressurized oil for driving each of the hydraulic actuators, an engine that drives the main pump, a plurality of control valves that distribute the pressurized oil to each of the hydraulic actuators in response to the lever operating of an operator, and a pilot pump that is driven by the engine to generate a pilot pressure for controlling opening/closing of the control valve. This construction machine controls the pilot pressure in accordance with the operating amount of the operating lever to distribute the pressurized oil to each of the hydraulic actuators in response to the lever operation by an operator, thus enabling the machine to move according to an intent of the operator. 
     Here, general hydraulic excavators control the pilot pressure by a hydraulic circuit. In this case, some of the hydraulic excavators are designed such that control by a controller is added to the control of the pilot pressure to prevent the hydraulic excavator from excavating excessively over a preset target excavating surface or the bucket from colliding with a vehicle body including a cab of the hydraulic excavator. This type of hydraulic excavator is provided with a posture sensor (for example, an tilt angle sensor, a potentiometer or the like) that measures a posture of the vehicle body or the working mechanism, a pressure sensor that measures a pilot pressure in accordance with an operating amount of the operating lever, a proportional solenoid valve that reduces the pilot pressure generated in accordance with the lever operating amount, another proportional solenoid valve that increases the pilot pressure regardless of the lever operation, and a controller that drives the proportional solenoid valve based upon posture information of the vehicle body or the working mechanism by the posture sensor and lever operating information by the pressure sensor. In this case, the controller corrects the movement of the working mechanism by reducing or increasing the pilot pressure in such a manner as to prevent the working mechanism from deviating from a predetermined spacious area when an operator operates the working mechanism. 
     On the other hand, there are some hydraulic excavators in which an electrical lever is adopted as the operating lever, and the pilot pressure is controlled only by the controller without providing a hydraulic circuit for controlling the pilot pressure. This hydraulic excavator is provided with the electrical lever that outputs an electrical operating signal in accordance with a lever operating amount, a proportional solenoid valve that controls pilot pressures of a plurality of hydraulic actuators, and a controller that drives the proportional solenoid valve based upon an operating signal that is outputted by the electrical lever. In this case, the controller controls each of the hydraulic pilot pressures in accordance with the lever operating amount to operate the machine. Further, there are other hydraulic excavators that are provided with a posture sensor that measures a posture of the vehicle body or the working mechanism. In this case, the controller controls the pilot pressure of each of the hydraulic actuators such that the working mechanism does not deviate from a predetermined spacious area, making it possible to operate the working mechanism. 
     These hydraulic excavators have a possibility that in a case where some malfunction occurs or noises are mixed in the controller, the controller drives the proportional solenoid valve in error. In this case, even when the operating lever is returned back to a neutral position, the machine does not stop possibly. In contrast thereto, for example, Patent Document 1 discloses a drive control device of a hydraulic machine that is provided with an electrical lever that outputs a lever operating amount signal in accordance with an operating amount, a neutral position signal outputting section configured to output a neutral position signal when the electrical lever is in a neutral position, a controller that drives a proportional solenoid valve that controls a pilot pressure of each of the actuators, based upon the lever operating amount signal, and a blockade device that performs an on/off operation of a drive signal between the controller and the proportional solenoid valve based upon the neutral position signal. The blockade device blocks the drive signal of the proportional solenoid valve of the concerned actuator when the operating lever of each of the actuators is in the neutral position. Accordingly, even when abnormality of the controller occurs, it is possible to stop the machine by returning the operating lever to the neutral position. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Patent Laid-Open No. Hei 01-97729 A 
     SUMMARY OF THE INVENTION 
     The drive control device according to Patent Document 1 can drive the actuator the lever operation of which is performed by an operator. However, the drive control device cannot drive the actuator the operating lever of which is in the neutral position since the drive signal of the proportional solenoid valve is blocked out. On the other hand, in a case of controlling the working mechanism such that the working mechanism does not deviate from the predetermined spacious area, the actuator corresponding to the lever in the neutral position that an operator is not operating is required to be controlled by the controller. 
     Therefore, the drive control device according to Patent Document 1 cannot control the working mechanism such that the working mechanism does not deviate from the predetermined spacious area. It should be noted that it is conceived to apply the technology in Patent Document 1 to the hydraulic excavator that controls the pilot pressure in response to the lever operation in the hydraulic circuit. In this case as well, however, the proportional solenoid valve that increases the pilot pressure regardless of the lever operation cannot be controlled by the controller such that the working mechanism does not deviate from the predetermined spacious area, creating a problem as similar to the above. 
     An object of the present invention is to provide a drive control device for a construction machine that can stop a machine by setting an operating lever to a neutral position whether a controller (control section) is normal or not, and can control a working mechanism from deviating from a predetermined spacious area. 
     A drive control device for a construction machine according to the present invention is provided with a plurality of operating levers that operate a plurality of hydraulic actuators provided in a machine; an operating amount measuring section configured to output an operating signal in accordance with an operating amount of each of the operating levers; a posture measuring section configured to output a posture signal in accordance with a posture of the machine; a plurality of control valves that control a drive of each of the hydraulic actuators; and a control section configured to output a drive signal for driving each of the control valves based upon the operating signal and the posture signal. 
     For solving the aforementioned problems, the configuration adopted by the invention defined in claim  1  characterized in including a drive permission determination section configured to determine whether or not the drive of each of the hydraulic actuators is permitted based upon the operating signal; and a drive signal selecting section configured to select the drive signal in such a manner as to drive the control valve with the drive signal to the hydraulic actuator the drive of which is permitted by the drive permission determination section, and not to drive the control valve to the hydraulic actuator the drive of which is not permitted by the drive permission determination section. 
     On the other hand, the configuration adopted by the invention defined in claim  4  is characterized in that: the drive control device for the construction machine includes: a drive signal upper limit determination section configured to determine an upper limit value of the drive signal for driving the control valve of each of the hydraulic actuators based upon the operating signal; and a drive signal selecting section configured to select the drive signal in such a manner as to drive the control valve with the drive signal to the hydraulic actuator the drive signal of which is equal to or less than the upper limit value determined by the drive signal upper limit determination section, and to drive the control valve with the upper limit value to the hydraulic actuator the drive signal of which is beyond the upper limit value determined by the drive signal upper limit determination section. 
     The drive control device for the construction machine according to the present invention can stop the machine by setting the operating lever to the neutral position whether the control section is normal or not, and can control the working mechanism from deviating from the predetermined spacious area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view showing a hydraulic excavator according to a first embodiment of the present invention. 
         FIG. 2  is a block diagram schematically showing a hydraulic system (hydraulic circuit) and an electrical system (control circuit) of the hydraulic excavator. 
         FIG. 3  is a block diagram showing a drive permission control part in  FIG. 2 . 
         FIG. 4  is a diagram schematically showing an example of a movement of the hydraulic excavator as viewed in the same direction as in  FIG. 1 . 
         FIG. 5  is an explanatory diagram of a drive permission setting table showing an example of a relation between a lever operation and a drive permission target. 
         FIG. 6  is an explanatory diagram showing a use example (determination example) of the drive permission setting table in  FIG. 5 . 
         FIG. 7  is a diagram schematically showing another example of the operation of the hydraulic excavator as viewed in the same direction as in  FIG. 1 . 
         FIG. 8  is an explanatory diagram of a drive permission setting table showing another example of a relation between the lever operation and the drive permission target. 
         FIG. 9  is an explanatory diagram showing a use example (determination example) of the drive permission setting table in  FIG. 8 . 
         FIG. 10  is a flow chart showing processing to be executed in a pilot pressure selecting part in  FIG. 3 . 
         FIG. 11  is a flow chart showing processing to be executed in a pilot pressure abnormality selecting part in  FIG. 3 . 
         FIG. 12  is a characteristic line diagram showing an example of a change with time in pilot pressure sensor information, drive permission signal, requested boost pilot pressure and boost pilot pressure. 
         FIG. 13  is a block diagram schematically showing a hydraulic system (hydraulic circuit) and an electrical system (control circuit) of a hydraulic excavator according to a second embodiment. 
         FIG. 14  is a block diagram showing a drive permission control part in  FIG. 13 . 
         FIG. 15  is an explanatory diagram of a drive upper limit value setting table showing an example of a relation between a lever operation and a pilot pressure upper limit value of each of actuator drives. 
         FIG. 16  is an explanatory diagram showing a use example (determination example) of the drive upper limit value setting table in  FIG. 15 . 
         FIG. 17  is a characteristic line diagram showing a relation between a lever operating amount and a pilot pressure upper limit value. 
         FIG. 18  is a flow chart showing processing to be executed in a pilot pressure selecting part in  FIG. 14 . 
         FIG. 19  is a characteristic line diagram showing an example of a change with time in lever operating amount, pilot pressure upper limit value, requested pilot pressure and pilot pressure. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, an explanation will be in detail made of an embodiment of a drive control device for a construction machine according to the present invention with reference to the accompanying drawings, by taking a case of being applied to a hydraulic excavator as an example. 
       FIG. 1  to  FIG. 12  show a first embodiment. In  FIG. 1 , a hydraulic excavator  1  that is a representative example of construction machines includes an automotive lower traveling structure  2  of a crawler type, an upper revolving structure  4  that is rotatably mounted on the lower traveling structure  2  through a revolving device  3 , and a working mechanism  5  that is tiltably provided in the front side of the upper revolving structure  4  in a front-rear direction. The lower traveling structure  2 , the revolving device  3  and the upper revolving structure  4  configure a vehicle body of the hydraulic excavator  1 , and the lower traveling structure  2 , the revolving device  3 , the upper revolving structure  4  and the working mechanism  5  configure a machine (construction machine). 
     Here, the lower traveling structure  2  includes a truck frame  2 A, a drive wheel  2 B provided on each of both sides of the truck frame  2 A in a left-right direction, an idler wheel  2 C provided on each of both the sides of the truck frame  2 A in the left-right direction in the opposite side to the drive wheel  2 B in the front-rear direction and a crawler belt  2 D wound around and between each of the drive wheels  2 B and each of the idler wheels  2 C (only the left components of the above are shown). The left and right drive wheels  2 B are respectively connected to left and right traveling hydraulic motors  2 E (only the left motor is shown) through a reduction mechanism. That is, the drive wheel  2 B is driven and rotated by the traveling hydraulic motor  2 E. On this occasion, the traveling hydraulic motor  2 E configures a hydraulic actuator that causes the hydraulic excavator  1  as a vehicle to move/travel. 
     The revolving device  3  is disposed on the lower traveling structure  2 . The revolving device  3  includes, for example, revolving bearings, a reduction mechanism (any of them is not shown) and a revolving hydraulic motor  3 A. The revolving device  3  revolves the upper revolving structure  4  to the lower traveling structure  2 . At this time, the revolving hydraulic motor  3 A configures a hydraulic actuator that operates/revolves the upper revolving structure  4  together with the working mechanism  5 . 
     The working mechanism  5  configures an excavating mechanism that is a front of the hydraulic excavator  1 . The working mechanism  5  is provided with, for example, a boom  5 A, an arm  5 B and a bucket  5 C as a working tool (attachment), and a boom cylinder  5 D, an arm cylinder  5 E and a bucket cylinder  5 F as a working tool cylinder, which drive the above components. The boom  5 A, the arm  5 B and the bucket  5 C are pinned to each other. The working mechanism  5  can perform the excavating work with expansion or contraction of each of the cylinders  5 D,  5 E,  5 F. At this time, each of the cylinders  5 D,  5 E,  5 F configures a hydraulic actuator that operates/excavates the working mechanism  5 . 
     That is, the boom cylinder  5 D, the arm cylinder  5 E and the bucket cylinder  5 F that are composed of the hydraulic cylinders, and the left and right traveling hydraulic motors  2 E and the revolving hydraulic motor  3 A that are composed of the hydraulic motors respectively configure hydraulic actuators (hydraulic equipment and hydraulic devices) that are driven (operable) based upon delivery of pressurized oil. The plurality of hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A are provided in the machine (construction machine) including the lower traveling structure  2 , the revolving device  3 , the upper revolving structure  4  and the working mechanism  5 . 
     The upper revolving structure  4  is provided with a revolving frame  6  formed as a support structural body on the front side in the front-rear direction of which the working mechanism  5  is mounted, a housing cover  7  that accommodates an engine  10 , a main pump  11 , a pilot pump  12 , a control valve device  14  and the like that are disposed on the revolving frame  6 , a counterweight  8  that acts as a weight balance to the working mechanism  5  and a cab  9  on which an operator boards. 
     Here, the engine  10  is configured by using an internal combustion engine such as a diesel engine, for example. The main pump  11  as a hydraulic pump and the pilot pump  12  as another hydraulic pump are connected mechanically to an output side of the engine  10 . A rotational number (rotational speed) and a driving force of the engine  10  are controlled by controlling a fuel injection quantity by an engine controller  10 A also called an ECU. The engine controller  10 A is connected to a main controller  32  as described later. 
     The driving force of the engine  10  is transmitted to the main pump  11  and the pilot pump  12 . Accordingly, the engine  10  configures a prime mover (rotational source or drive source) for driving/rotating the main pump  11  and the pilot pump  12 . It should be noted that the prime mover that drives the main pump  11  and the pilot pump  12  can be configured with an engine unit as an internal combustion engine, and besides, may be configured with, for example, an engine and an electric motor or an electric motor unit. 
     The main pump  11  is driven/rotated by the engine  10 . The main pump  11  configures a main hydraulic source together with a hydraulic oil tank  13  (refer to  FIG. 2 ) for reserving hydraulic oil. The main pump  11  is configured by, for example, a variable displacement swash plate hydraulic pump, and has a regulator (capacity variable part or tilt actuator)  11 A (refer to  FIG. 2 ) that adjusts a pump capacity. The regulator  11 A is connected to the main controller  32  (vehicle body control part  36  thereof), and is variably controlled by the main controller  32  (vehicle body control part  36  thereof). That is, the pump capacity of the main pump  11  is adjusted by the main controller  32 . The main pump  11  is driven/rotated by the engine  10  to deliver pressurized oil to each of the hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A through the control valve device  14 . 
     The pilot pump  12  is driven/rotated by the engine  10  as similar to the main pump  11 . The pilot pump  12  is configured as, for example, a fixed displacement hydraulic pump, and configures a pilot hydraulic source together with the hydraulic oil tank  13 . The pilot pump  12  delivers a pilot pressure to the control valve device  14  through an operating lever device  15  provided in the inside of the cab  9 . 
     The control valve device  14  distributes the pressurized oil generated by the main pump  11  to each of the hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A. Therefore, the control valve device  14  is provided between the main pump  11  and each of the hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A. The control valve device  14  is a group of control valves configured by a plurality of control valves  14 A (refer to  FIG. 2 ). Each of the control valves  14 A is configured by a directional control valve having six ports and three positions, for example, and switches/controls the pressurized oil to be delivered to each of the hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A from the main pump  11 . 
     In this case, the control valve device  14  (each of the control valves  14 A) is operated (switched) by the operating lever device  15 . Therefore, a pair of hydraulic pilot parts (not shown) is provided in each of the control valves  14 A in the control valve device  14 , respectively. A pilot pressure (switching signal) is supplied to the hydraulic pilot part of the control valve  14 A based upon an operation of the operating lever device  15 . Accordingly, each of the control valves  14 A controls a drive of each of the hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A. 
     An operator&#39;s seat (not shown) on which an operator is seated, the plurality of operating lever device  15  to be operated by an operator, a monitor/operating panel device  16  that notifies an operator of various information of the machine and sets a drive mode and the like, and the like are provided in the inside of the cab  9 . In addition, the main controller  32  is provided in the inside of the cab  9  to control the main pump  11  and the control valve device  14  and give a command to the engine controller  10 A. It should be noted that in  FIG. 1 , the main controller  32  is provided in the inside of the cab  9  of the upper revolving structure  4 , but the main controller  32  may be provided, for example, outside of the cab  9  of the upper revolving structure  4 . 
     The plurality of operating lever devices  15  are configured of an operating lever/pedal device for travel, an operating lever device for work, and the like. That is, each of the operating lever devices  15  is configured as a pilot operating valve (hydraulic type lever device) composed of a pressure reducing valve type pilot valve, for example, and is provided with an operating lever  15 A to be operated by an operator. The operating lever device  15  including the operating lever  15 A is to operate each of the hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A. 
     That is, when an operator manually performs atilt operation (lever operation) of the operating lever  15 A, a pilot pressure (switch hydraulic signal) in proportion to an operating amount of the operating lever  15 A is supplied to each of the control valves  14 A (hydraulic pilot part thereof) configuring the control valve device  14  from the operating lever device  15 . As a result, a position of a spool in each of the control valves  14 A is displaced to control a direction and a flow amount of the pressurized oil to be supplied/discharged to each of the hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A, thus making it possible to perform excavation by the working mechanism  5 , travel of the lower traveling structure  2 , revolution of the upper revolving structure  4 , and the like. 
     The monitor/operating panel device  16  aims at informing an operator of a state of the machine concerning a fuel remaining amount, an engine cooling water temperature and the like, as well as selecting and setting a driving mode of the hydraulic excavator  1 , and the like. Therefore, the monitor/operating panel device  16  includes, for example, a liquid crystal monitor as a display screen, an acoustic device that outputs sounds, and an operating panel as an input interface of an operator. When the monitor/operating panel device  16  informs an operator of abnormality, the monitor/operating panel device  16  displays occurrence of the abnormality, a content of the abnormality and the like on the display screen and/or outputs sounds such as a warning sound, a voice and the like from the acoustic device. 
     Next, an explanation will be made of a hydraulic circuit  21  for driving the hydraulic excavator  1  with reference to  FIG. 2  in addition to  FIG. 1 . It should be noted that in  FIG. 2 , for avoiding complication of the figure, plural pieces of hydraulic equipment are represented by one piece of equipment. Specifically, in  FIG. 2 , the plurality of control valves  14 A configuring the control valve device  14  are represented by one control valve  14 A, and the plurality of the hydraulic actuators  5 D,  5 E,  5 F,  2 E,  3 A are represented by one hydraulic actuator (hereinafter, referred to as “hydraulic actuator  22 ”), the plurality of operating lever devices  15  are represented by one operating lever device  15 , a plurality of pressure-reduction proportional solenoid valves  23  are represented by one pressure-reduction proportional solenoid valve  23  and a plurality of boost proportional solenoid valves  25  are represented by one boost proportional solenoid valve  25 . 
     The hydraulic circuit  21  in the actual hydraulic excavator  1  is provided with, for example, the six hydraulic actuators  22 , the six control valves  14 A, the four operating lever devices  15  (for example, the two operating lever devices for work corresponding to a total of four directions and the two lever/pedal devices for travel), the four or six pressure-reduction proportional solenoid valves  23  and the four or six boost proportional solenoid valves  25 . In addition, in  FIG. 2 , a plurality of pressure sensors  28  and a plurality of other pressure sensors  29  as well to be described later each are represented by one sensor. The hydraulic circuit  21  in the actual hydraulic excavator  1  is provided with, for example, the four or six pressure sensors  28  and the other pressure sensors  29 , respectively. 
     As shown in  FIG. 2 , the hydraulic circuit  21  in the hydraulic excavator  1  is provided with the engine  10 , the main pump  11 , the plurality of control valves  14 A, the plurality of hydraulic actuators  22 , the pilot pump  12 , the plurality of operating lever devices  15 , the plurality of pressure-reduction proportional solenoid valves  23 , the plurality of boost proportional solenoid valves  25 , the plurality of pressure sensors  28 , the plurality of other pressure sensors  29 , a blockade solenoid valve  30 , a posture sensor  31 , the main controller  32  and the monitor/operating panel device  16 . 
     The pressure-reduction proportional solenoid valve  23  is provided between the operating lever device  15  and the control valve  14 A (the pilot part thereof). That is, the pressure-reduction proportional solenoid valve  23  is provided on the way of a pilot line  24  connecting between the operating lever device  15  and the control valve  14 A. The pressure-reduction proportional solenoid valve  23  is configured by a regular opening proportional solenoid valve, for example, and is connected to the main controller  32  (an area limit control part  40  thereof). The pressure-reduction proportional solenoid valve  23  reduces the pilot pressure to be supplied to the control valve  14 A (a pilot part thereof) based upon a command (drive signal) of the main controller  32 . 
     The boost proportional solenoid valve  25  is provided between the pilot pump  12  and the control valve  14 A (the pilot part thereof). That is, the boost proportional solenoid valve  25  is branched from a pilot delivery line  26  connecting between the pilot pump  12  and the operating lever device  15 , and is provided on the way of a pilot branch line  27  connected to between the pressure-reduction proportional solenoid valve  23  in the pilot line  24  and the control valve  14 A. The boost proportional solenoid valve  25  is configured by a regular closing proportional solenoid valve, for example, and is connected to the main controller  32  (a drive permission control part  44  thereof). The boost proportional solenoid valve  25  reduces the pilot pressure to be supplied to the control valve  14 A (a pilot part thereof) based upon a command (drive signal) of the main controller  32 . 
     The pressure sensor  28  is provided between the operating lever device  15  and the pressure-reduction proportional solenoid valve  23  in the pilot line  24 . The pressure sensor  28  is connected to the main controller  32  (the vehicle body control part  36 , the area limit control part  40  and the drive permission control part  44  thereof). The pressure sensor  28  detects a pilot pressure  37  that is outputted from the operating lever device  15 , and outputs a detection signal corresponding to the pilot pressure  37  to the main controller  32 . That is, the pressure sensor  28  configures an operating amount measuring section that outputs an operating signal in accordance with an operating amount of each of the operating levers  15 A. 
     The other pressure sensor  29  is provided between a connecting part of the pilot line  24  to the pilot branch line  27  and the control valve  14 A (the pilot part thereof). The other pressure sensor  29  is connected to the main controller  32  (the drive permission control part  44  thereof). The other pressure sensor  29  detects a pilot pressure  35  that is supplied to the pilot part of the control valve  14 A, and outputs a detection signal corresponding to the pilot pressure  35  to the main controller  32 . 
     The blockade solenoid valve  30  is provided between the pilot pump  12  in the pilot delivery line  26  and the operating lever device  15 , more specifically, between a branch part to the pilot branch line  27  and the pilot pump  12 . The blockade solenoid valves  30  is configured by, for example, a regular opening solenoid switching valve, and is connected to the main controller  32  (the drive permission control part  44  thereof). The blockade solenoid valve  30  blocks a source pressure  34  of the pilot pressure to be supplied to the operating lever device  15  and the boost proportional solenoid valve  25  from the pilot pump  12 , based upon a command of the main controller  32 . 
     The posture sensor  31  is composed of sensors (a sensor group of a plurality of sensors) that detect (measure) the posture of the hydraulic excavator  1 . That is, the posture sensor  31  is provided in the machine including the working mechanism  5  and the upper revolving structure  4  to detect (measure) various kinds of state amounts for estimating the posture of the machine. The posture sensor  31  includes, for example, a tilt angle sensor that measures a tilt of the upper revolving structure  4 , an angle sensor that detects an angle (for example, revolving angle) of the upper revolving structure  4 , a rotational angle sensor for boom that detects a rotational angle of the boom  5 A of the working mechanism  5 , a rotational angle sensor for arm that detects a rotational angle of the arm  5 B of the working mechanism  5  and a rotational angle sensor for bucket that detects a rotational angle of the bucket  5 C of the working mechanism  5 . Accordingly, the posture sensor  31  configures a posture measuring section that outputs a posture signal (detection signal) in accordance with the posture of the machine. 
     It should be noted that the rotational angle sensor of the working mechanism  5  may be configured by, for example, a potentiometer, a tilt angle sensor, a cylinder stroke sensor, and/or a combination of them. In addition, the angle sensor of the upper revolving structure  4  may be configured by a sensor that measures a relative angle to the lower traveling structure  2 , and besides, may be configured by a sensor that measures an angle on terrestrial coordinates using a global positioning navigation satellite system (GNSS). 
     Such a posture sensor  31  is connected to the main controller  32  (the area limit control part  40  thereof). The main controller  32  (the area limit control part  40  thereof) is provided with a function of controlling the working mechanism  5  such that the working mechanism  5  does not move beyond a preset space area, that is, an area limit control function of controlling the working mechanism  5  based upon measured data of the posture sensor  31  and a lever operation of an operator (for example, a detection signal of the pressure sensor  28 ). An application example of the area limit control function may include avoidance of collision of the working mechanism  5  with the cab  9 , prevention of excessive excavation in an excavating work, avoidance of collision of an upper side of the machine with facilities in a work site, and the like. 
     Next, an explanation will be made of a system configuration for realizing the area limit control function of the hydraulic excavator  1 . 
     The driving force of the engine  10  is transmitted to the main pump  11  and the pilot pump  12 . The main pump  11  generates pressurized oil  33  for driving (operating) each of the hydraulic actuators  22 . The pilot pump  12  generates a source pressure  34  of the pilot pressure for controlling the control valve  14 A through the operating lever  15 A in the operating lever device  15  by an operator. The control valve  14 A controls a delivery amount and a delivery direction of the pressurized oil to the hydraulic actuator  22  in accordance with the pilot pressure  35  (of the control valve  14 A-side) determined in accordance with an operating amount of each of the operating levers  15 A and the like. 
     The main controller  32  includes a microcomputer provided with, for example, a memory and a UPU (computing device). The main controller  32  includes the vehicle body control part  36 , the area limit control part  40  and the drive permission control part  44 . It should be noted that the vehicle body control part  36  is mounted in the main controller  32 , but the area limit control part  40  and the drive permission control part  44  respectively may be mounted in the main controller  32  or may be mounted in a controller aside from the main controller  32 . 
     The vehicle body control part  36  controls a rotational speed of the engine  10 , a flow amount (delivery amount) of the main pump  11  and the like based upon an operating amount of the operating lever  15 A calculated from the measured data  38  of the pilot pressure  37  (in the operating lever  15 A-side) measured by each of the pressure sensors  28 , a working state (operating state) of the engine  10 , a delivery pressure of the main pump  11 , a load pressure of each of the hydraulic actuators  22 , and the like. Therefore, the vehicle body control part  36  is connected to each of the pressure sensors  28 , the engine  10  (the engine controller  10 A thereof), the main pump  11  (the regulator  11 A thereof) and each of the hydraulic actuators  22  (pressure sensors (not shown) thereof). It should be noted that in some cases the vehicle body control part  36  outputs a requested pressure-reduction pilot pressure  39  to the pilot pressure  35  for controlling distribution of the pressurized oil to each of the hydraulic actuators  22  from the main pump  11 . Therefore, the vehicle body control part  36  is connected to the area limit control part  40 . The requested pressure-reduction pilot pressure  39  is outputted corresponding to each of the hydraulic actuators  22 . 
     Further, a system for realizing the area limit control function is provided with the pressure-reduction proportional solenoid valve  23 , the boost proportional solenoid valve  25 , the blockade solenoid valve  30 , the pressure sensor  29 , the area limit control part  40  and the drive permission control part  44 . The pressure-reduction proportional solenoid valve  23  is a solenoid valve (speed-reduction proportional solenoid valve) that reduces the pilot pressure  35  to decelerate or stop the hydraulic actuator  22 . The boost proportional solenoid valve  25  is a solenoid valve (speed-increase proportional solenoid valve) that increases the pilot pressure  35  to activate or speed up the hydraulic actuator  22 . The blockade solenoid valve  30  is a solenoid valve that blocks the source pressure  34  of the pilot pressure. The pressure sensor  29  measures the pilot pressure  35  for controlling the control valve  14 A. 
     The area limit control part  40  has an input side that is connected to the posture sensor  31 , each of the pressure sensors  28  and the vehicle body control part  36  and an output side that is connected to each of the pressure-reduction proportional solenoid valves  23  and the drive permission control part  44 . The area limit control part  40  configures a control section (area limit control section) that outputs a drive signal (drive current  42  and requested boost pilot pressure  43 ) for driving each of the control valves  14 A, based upon an operating signal (signal of the pilot pressure  37 ) in accordance to the operating amount of each of the operating levers  15 A and a posture signal (detection signal of a state amount concerning the posture) of the posture sensor  31 . That is, the area limit control part  40  estimates a posture of the machine based upon the measured data  41  of the posture sensor  31  in the hydraulic excavator  1 , and calculates an operating amount of the operating lever  15 A by an operator based upon the measured data  38  of the pilot pressure  37  of each of the pressure sensors  28 . 
     In addition, the area limit control part  40 , for preventing the machine from deviating from the preset space area, outputs the drive current  42  of the pressure-reduction proportional solenoid valve  23  in accordance with the posture of the machine, the operation of an operator, the requested pressure-reduction pilot pressure  39  outputted from the vehicle body control part  36  and the like, to decelerate or stop the desired hydraulic actuator  22 . Otherwise, the area limit control part  40 , for preventing the machine from deviating from the preset space area, outputs a requested boost pilot pressure  43  to the drive permission control part  44  for activating or speeding up the desired hydraulic actuator  22  by driving the boost proportional solenoid valve  25  in accordance with the posture of the machine, the operation of an operator, the requested pressure-reduction pilot pressure  39  and the like. The drive current  42  and the requested boost pilot pressure  43  are outputted corresponding to each of the hydraulic actuators  22 . 
     The drive permission control part (operation permission control part)  44  has an input side that is connected to each of the pressure sensors  28 , the area limit control part  40  and each of the other pressure sensors  29  and an output side that is connected to each of the boost proportional solenoid valves  25 , the monitor/operating panel device  16  and the blockade solenoid valve  30 . The drive permission control part  44  determines presence/absence of an operation of the operating lever  15 A by an operator based upon the measured data  38  of the pilot pressure  37 , and determines whether or not to permit a drive (operation) of each of the hydraulic actuators  22  according to the operating state. The drive permission control part  44  outputs the drive current  45  of the boost proportional solenoid valve  25  to the boost proportional solenoid valve  25  in response to the requested boost pilot pressure  43  outputted from the area limit control part  40  to the hydraulic actuator  22  the drive of which is permitted. Accordingly, the desired hydraulic actuator  22  is activated or speeded up. The drive current  45  is outputted corresponding to each of the hydraulic actuators  22 . 
     On the other hand, the drive permission control part  44  does not output the drive current  45  to the hydraulic actuator  22  the drive of which is not permitted regardless of a value of the requested boost pilot pressure  43 . Accordingly, even when the incorrect requested boost pilot pressure  43  is outputted due to the abnormality of the area limit control part  40 , the drive permission control part  44  can prevent the boost proportional solenoid valve  25  in the hydraulic actuator  22  the drive of which is not permitted from being driven. Further, the drive permission control part  44  can prevent permission of drives of all the hydraulic actuators  22  when the operating lever  15 A is in a neutral position. As a result, an operator can prevent the drives of all the boost proportional solenoid valves  25  by returning the operating lever  15 A back to the neutral position, stopping an inappropriate movement of the hydraulic actuator  22 . 
     In addition, the drive permission control part  44  can output abnormality information  46  that the requested boost pilot pressure  43  is abnormal to the monitor/operating panel device  16  in a case where the requested boost pilot pressure  43  is outputted to the hydraulic actuator  22  the drive of which is not permitted. Thereby, the abnormality can be informed to an operator. In addition, the drive permission control part  44  compares the pilot pressure  35  detected by the other pressure sensor  29  with a boost pilot pressure  51  to be described later, making it possible to determine the abnormality of the pilot pressure  35 . In a case where the pilot pressure  35  is determined to be abnormal, the drive permission control part  44  outputs a drive current  47  for driving (closing) the blockade solenoid valve  30  to the blockade solenoid valve  30 . Accordingly, the source pressure  34  of the pilot pressure can be blocked to stop the machine. 
     Next, an explanation will be made of the drive permission control part  44  with reference to  FIG. 3  to  FIG. 9 . 
     As shown in  FIG. 3 , the drive permission control part  44  is provided with a drive permission determination part  48 , a pilot pressure selecting part  50 , a solenoid valve drive part  53 , a pilot pressure abnormality detecting part  54  and an abnormality notification part  58 . The drive permission determination part  48  has an input side that is connected to each of the pressure sensors  28  and an output side that is connected to the pilot pressure selecting part  50 . The drive permission determination part  48  configures a drive permission determination section that determines whether or not to permit the drive of each of the hydraulic actuators  22  based upon an operating signal in accordance with the operating amount of each of the operating levers  15 A and outputs the determination. That is, the drive permission determination part  48  determines the hydraulic actuator  22  the drive of which is permitted according to the operating state of each of the operating levers  15 A by an operator based upon the pilot pressure sensor information of each of the pressure sensors  28 , that is, the measured data  38  of the pilot pressure  37 . In addition, the drive permission determination part  48  outputs a drive permission signal  49  corresponding to the determination result (permission/non-permission of the drive of the hydraulic actuator  22 ) to the pilot pressure selecting part  50 . 
     The pilot pressure selecting part  50  has an input side that is connected to the area limit control part  40  and the drive permission determination part  48  and an output side that is connected to the solenoid valve drive part  53 , the pilot pressure abnormality detecting part  54  and the abnormality notification part  58 . The pilot pressure selecting part  50  is formed as a drive signal selecting section configured to select a drive signal (the requested boost pilot pressure  43  from the area limit control part  40 ) in such a way as to drive the control valve  14 A by the drive signal (requested boost pilot pressure  43 ) to the hydraulic actuator  22  the drive of which is permitted by the drive permission determination part  48  and not to drive the control valve  14 A to the hydraulic actuator  22  the drive of which is not permitted. 
     That is, the pilot pressure selecting part  50  selects the requested boost pilot pressure  43  in response to the drive permission signal  49  outputted from the drive permission determination part  48 , that is, the requested boost pilot pressure  43  of the hydraulic actuator  22  the drive of which is permitted as the boost pilot pressure  51 , out of the requested boost pilot pressures  43  from the area limit control part  40 . In addition, the pilot pressure selecting part  50  outputs the boost pilot pressure  51  to the solenoid valve drive part  53  and the pilot pressure abnormality detecting part  54 . 
     Further, the pilot pressure selecting part  50 , when the requested boost pilot pressure  43  of the hydraulic actuator  22  the drive of which is not permitted is not zero, outputs requested-boost pilot pressure abnormality information  52  that the requested boost pilot pressure  43  is abnormal to the abnormality notification part  58 . That is, the pilot pressure selecting part  50  is also formed as an abnormality detecting section (requested-boost pilot pressure abnormality detecting section) that detects control abnormality based upon the drive signal (requested boost pilot pressure  43 ) of each of the hydraulic actuators  22  and the drive permission signal  49  determined in the drive permission determination part  48 . It should be noted that the processing in  FIG. 10  to be executed in the pilot pressure selecting part  50  will be explained later. 
     The solenoid valve drive part  53  has an input side that is connected to the pilot pressure selecting part  50  and an output side that is connected to the boost proportional solenoid valve  25 . The solenoid valve drive part  53  outputs the drive current  45  of the boost proportional solenoid valve  25  to the boost proportional solenoid valve  25  based upon the boost pilot pressure  51  from the pilot pressure selecting part  50 . Thereby, the boost proportional solenoid valve  25  opens in response to the drive current  45  to supply the pilot pressure corresponding to the boost pilot pressure  51  to the pilot part of the control valve  14 A in the hydraulic actuator  22  the drive of which is permitted. 
     The pilot pressure abnormality detecting part  54  has an input side that is connected to the pilot pressure selecting part  50  and each of the other pressure sensors  29  and an output side that is connected to the abnormality notification part  58  and the blockade solenoid valve  30 . The pilot pressure abnormality detecting part  54  compares the measured data of the pilot pressure  35  as pilot pressure sensor information  55  of each of the other pressure sensors  29  with the boost pilot pressure  51  from the pilot pressure selecting part  50  to detect the abnormality of the pilot pressure  35 . The pilot pressure abnormality detecting part  54  outputs the pilot pressure abnormality information  56  that the pilot pressure  35  is abnormal to the abnormality notification part  58  in a case where the abnormality of the pilot pressure  35  is detected. 
     Together with it, the pilot pressure abnormality detecting part  54  outputs a pilot pressure blocking request  57  as a command signal (drive current  47 ) for blocking the pilot pressure (the source pressure  34  thereof) to the blockade solenoid valve  30 . That is, the pilot pressure abnormality detecting part  54  is formed as another abnormality detecting section (pilot pressure abnormality detecting section) that detects the control abnormality based upon a drive signal (boost pilot pressure  51 ) selected in the pilot pressure selecting part  50  and an actual drive signal (pilot pressure  35 ) to be supplied to the control valve  14 A, and a drive signal stopping section that blocks a drive signal (pilot pressure) to the control valve  14 A when the abnormality is detected. It should be noted that the processing in  FIG. 11  to be executed in the pilot pressure abnormality detecting part  54  will be explained later. 
     The abnormality notification part  58  has an input side that is connected to the pilot pressure selecting part  50  and the pilot pressure abnormality detecting part  54  and an output side that is connected to the monitor/operating panel device  16 . The abnormality notification part  58  is formed as an abnormality notification section configured to notify the abnormality when the control abnormality is detected by the pilot pressure selecting part  50  and/or the pilot pressure abnormality detecting part  54 . That is, the abnormality notification part  58  outputs the abnormality information  46  concerning occurrence of the abnormality and corresponding to a content of the abnormality to the monitor/operating panel device  16  based upon the requested-boost pilot pressure abnormality information  52  from the pilot pressure selecting part  50  and/or the pilot pressure abnormality information  56  from the pilot pressure abnormality detecting part  54 . 
     Here, the drive permission determination part  48  can preliminarily set the hydraulic actuator  22  the drive of which is permitted for each lever operation of an operator.  FIG. 5  and  FIG. 8  are drive permission setting tables  60 ,  62  that show setting examples of a movement of the hydraulic actuator  22  permitted at each lever operation time in a matrix. The drive permission determination part  48 , in a case where one or more of the lever operations are performed, determines whether or not the movement of each of the hydraulic actuators  22  is permitted by any of the lever operations based upon the drive permission setting tables  60 ,  62 . In addition, the drive permission determination part  48  determines the movements of all the hydraulic actuators  22  as non-permission in a case where any of the lever operations is not performed, that is, when the operating lever  15 A is in the neutral position, and the drive permission signal  49  corresponding to this determination result is outputted as a drive permission signal En. 
     The setting of the drive permission setting table  60  in  FIG. 5  is made to move the boom  5 A in a raising direction by the area limit control part  40  at the time of operating the arm  5 B or the bucket  5 C, such that the bucket  5 C does not dig the side deeper than a target surface  61  in an excavating work or a uniform work as shown in  FIG. 4 . When an operator performs the arm pulling operation and the bucket excavating operation, as shown in  FIG. 6 , the drive permission determination part  48  permits the boom raising as well in addition to the arm pulling and the bucket excavating. Accordingly, the boom raising movement by the area limit control part  40  is made possible without the boom raising operation by an operator. On the other hand, even when the area limit control part  40  outputs the incorrect requested boost pilot pressure  43  due to malfunction of the area limit control part  40 , when an operator returns the operating lever  15 A back to the neutral position, the determination results of the drive permission determination part  48  are all made to the non-permission. Thereby, it is possible to stop the inappropriate movement of the hydraulic actuator  22 . 
     On the other hand, the setting of the drive permission setting table  62  in  FIG. 8 , as shown in  FIG. 7 , is to dispose an interference prevention area  63  in such a manner that the bucket  5 C does not collide with the upper revolving structure  4  and the lower traveling structure  2 , and moves the arm  5 B in a pushing direction by the area limit control part  40  at the time of operating the boom  5 A, the arm  5 B and the bucket  5 C. When an operator performs the boom raising operation and the bucket excavating operation, the drive permission determination part  48 , as shown in  FIG. 9 , permits the arm pulling in addition to the boom raising and the bucket excavating. Thereby, the arm pushing movement by the area limit control part  40  is made possible even without the arm pushing operation by an operator. On the other hand, even when the area limit control part  40  outputs the incorrect requested boost pilot pressure  43  due to malfunction of the area limit control part  40 , when an operator returns the operating lever  15 A back to the neutral position, the determination results of the drive permission determination part  48  are all made to the non-permission. Therefore, it is possible to stop the inappropriate movement of the hydraulic actuator  22 . 
     Thus, the drive permission determination part  48  is provided with the drive permission setting table  60  as shown in  FIG. 5  and/or the drive permission setting table  62  as shown in  FIG. 8 . The drive permission setting tables  60 ,  62  each represent a corresponding relation between a lever operation by an operator and a lever operation for permitting a drive in response thereto. In addition, the drive permission setting table  60  in  FIG. 5  and/or the drive permission setting table  62  in  FIG. 8  are configured as drive permission setting sections configured to set one or a plurality of lever operations for permitting a drive to each of the hydraulic actuators  22 . It should be noted that the drive permission setting section is only required to set a corresponding relation between a lever operation by an operator and a lever operation for permitting a drive in response thereto, and is not limited to the tables (matrixes) as shown in  FIG. 5  and in  FIG. 8 . In addition, the drive permission setting tables  60 ,  62  are not limited to those in  FIG. 5  and in  FIG. 8 , but various kinds of the drive permission setting tables (a corresponding relation between a lever operation by an operator and a lever operation for permitting a drive in response thereto) may be set in response to the limit control of the area limit control part  40 . 
     Next,  FIG. 10  shows the control processing that is executed in the pilot pressure selecting part  50 . The control processing in  FIG. 10  is repeatedly executed in a predetermined control cycle during power supply to the main controller  32  (pilot pressure selecting part  50 ), for example. It should be noted that each step in a flow chart shown in  FIG. 10  (and in  FIG. 11  and in  FIG. 18  to be described later) is shown in a sign of “S” (for example, step  1 =S 1 ). 
     When the control processing of the pilot pressure selecting part  50  starts, at step S 1 , the pilot pressure selecting part  50  acquires the requested boost pilot pressure  43  outputted from the area limit control part  40 , that is, a requested boost pilot pressure Pcr. At a subsequent step S 2 , the drive permission signal  49  corresponding to the drive permission determination result outputted from the drive permission determination part  48 , that is, a drive permission signal En is acquired. At step  3 , it is determined whether or not the drive permission signal En is “drive permission”. 
     At S 3 , in a case where “YES” determination is made, that is, in a case where it is determined that the drive permission signal En is “drive permission”, the process goes to S 4 . At S 4 , the requested boost pilot pressure Pcr is defined as a boost pilot pressure Pc. That is, the boost pilot pressure  51  is outputted as the boost pilot pressure Pc (=Pcr) to the solenoid valve drive part  53  and the pilot pressure abnormality detecting part  54 , and the process returns (the process returns to START, and the processing after S 1  is repeated). 
     On the other hand, at S 3 , in a case where “NO” determination is made, that is, in a case where it is determined that the drive permission signal En is “drive non-permission”, the process goes to S 5 . At S 5 , the requested boost pilot pressure Pcr is defined as zero. That is, the boost pilot pressure  51  is outputted as the boost pilot pressure Pc (=0) to the solenoid valve drive part  53  and the pilot pressure abnormality detecting part  54 . At subsequent step S 6 , it is determined whether or not the requested boost pilot pressure Pcr acquired at S 1  is a value greater than zero. 
     In a case where “YES” determination is made at S 6 , that is, in a case where it is determined that the requested boost pilot pressure Pcr acquired at S 1  is the value greater than zero, the process goes to S 7 . At S 7 , the requested-boost pilot pressure abnormality information  52  as abnormality information that the requested boost pilot pressure Pcr is abnormal is outputted to the abnormality notification part  58 , and the process returns. On the other hand, in a case where at S 6  “NO” determination is made, that is, in a case where it is determined that the requested boost pilot pressure Pcr acquired at S 1  is not the value greater than zero (Pcr=0), the process returns without through S 7 . These processes, that is, the processing to be executed in the pilot pressure selecting part  50  is executed to the movement in each of the hydraulic actuators  22 . 
     Next,  FIG. 11  shows the control processing that is executed in the pilot pressure abnormality detecting part  54 . The control processing as well in  FIG. 11 , as similar to the processing in  FIG. 10 , is repeatedly executed in a predetermined control cycle, for example, during power supply to the main controller  32  (pilot pressure abnormality detecting part  54 ). 
     When the control processing of the pilot pressure abnormality detecting part  54  starts, at S 11 , the pilot pressure abnormality detecting part  54  stores the boost pilot pressure  51  outputted from the pilot pressure selecting part  50 , that is, the boost pilot pressure Pc, and the process returns (the process is back to START through RETURN, and the processing at S 11  is repeated). In addition, the processing after S 21  is also executed in parallel to the processing at S 11 . 
     At S 21 , a boost pilot pressure Pcd stored prior to the present point by time Td is read out. It should be noted that time Td is a sum of a time from a point where the boost pilot pressure Pc is determined to a point where the pilot pressure  35  in accordance therewith is generated and a time from a point where the generated pilot pressure  35  is measured by the other pressure sensor  29  to a point where the pilot pressure abnormality detecting part  54  acquires the pilot pressure Pr as the measured result (pilot pressure sensor information  55 ). That is, the boost pilot pressure Pcd is equivalent to the past boost pilot pressure Pc corresponding to the pilot pressure Pr acquired by the pilot pressure abnormality detecting part  54 . 
     At S 22  subsequent to S 21 , the pilot pressure abnormality detecting part  54  acquires an actual pilot pressure Pr from the other pressure sensor  29 , which is compared with the boost pilot pressure Pcd read out at S 1 . That is, at subsequent S 23 , it is determined whether or not a difference between the actual pilot pressure Pr and the boost pilot pressure Pcd is less than dPce as a predetermined abnormality determination difference threshold value. At S 23  in a case where “YES” determination is made, that is, in a case where it is determined that the difference between the actual pilot pressure Pr and the boost pilot pressure Pcd is less than dPce, the pilot pressure  35  can be determined to be correct. Therefore, the process goes to S 24 , wherein an error counter EC is cleared to return the process (the process is back to START through RETURN, and the processing after S 21  is repeated). It should be noted that the threshold value dPce can be set as a value in more than which a high possibility that the abnormality of the pilot pressure  35  is generated can be determined, for example. The threshold value dPce is in advance found by, for example, experiments, calculations, simulations and the like to make it possible to perform the determination of the abnormality with accuracy. 
     On the other hand, at S 23 , in a case where “NO” determination is made, that is, in a case where it is determined that the difference between the actual pilot pressure Pr and the boost pilot pressure Pcd is equal to or more than dPce, the pilot pressure  35  can be determined to be incorrect. Therefore, the process goes to S 25 , wherein an error counter is incremented. In addition, at subsequent S 26  it is determined whether or not the error counter EC is equal to or more than RC as a predetermined threshold value to the times of abnormality determinations. 
     At S 26 , in a case where “YES” determination is made, that is, in a case where it is determined that the error counter EC is equal to or more than RC, the process goes to S 27 , wherein a pilot pressure blocking request  57  as a command signal for blocking the source pressure  34  of the pilot pressure, that is, a pilot pressure blocking request DesPi is outputted to the blockade solenoid valve  30 . Thereby, the blockade solenoid valve  30  is made to a closed position (blocked position) to stop the machine. At subsequent S 28 , the pilot pressure abnormality information  56  that the pilot pressure  35  is abnormal is outputted to the abnormality notification part  58 . Accordingly, the abnormality notification part  58  outputs the abnormality information  46  concerning the occurrence of the abnormality and corresponding to the content of the abnormality to the monitor/operating panel device  16 , making it possible to inform an operator of the abnormality. When at S 28 , the pilot pressure abnormality information  56  is outputted, the process returns. It should be noted that the threshold value RC may be set as a value in more than which it can be determined that the machine is preferably stopped, for example. The threshold value RC is in advance determined by, for example, experiments, calculations, simulations and the like to make it possible to appropriately perform the stop of the machine. 
     On the other hand, at S 26 , in a case where “NO” determination is made, that is, in a case where it is determined that the error counter EC is less than RC, the process returns without through S 27  and S 28 . These processes, that is, the processing to be executed in the pilot pressure abnormality detecting part  54  is executed to the movement in each of the hydraulic actuators  22 . That is, the pilot pressure blocking request DesPi and the blockade solenoid valve  30  may be provided in each of the hydraulic actuators  22 , respectively. In this case, it is possible to stop only the movement of the hydraulic actuator  22  corresponding to the abnormality. On the other hand, the blockade solenoid valve  30  may be not provided and S 27  may be omitted. In this case, it is possible to stop the machine by performing a key-off operation by an operator based upon the notification of the abnormality by the monitor/operating panel device  16 . 
     The hydraulic excavator  1  according to the present embodiment has the aforementioned configuration, and next, an explanation will be made of the movement. 
     When an operator having boarded on the cab  9  activates the engine  10 , the main pump  11  and the pilot pump  12  are driven by the engine  10 . Accordingly, the pressurized oil delivered from the main pump  11  is supplied to each of the hydraulic actuators  22  (that is, the left and right traveling hydraulic motors  2 E, the revolving hydraulic motor  3 A, the boom cylinder  5 D, the arm cylinder  5 E and the bucket cylinder  5 F in the working mechanism  5 ) in response to the operation of the operating lever  15 A in the operating lever device  15  provided in the inside of the cab  9  (for example, a lever operation of the operating lever for work, a lever operation of the operating lever/pedal for travel, and a pedal operation). As a result, the hydraulic excavator  1  can perform the traveling movement by the lower traveling structure  2 , the revolving movement by the upper revolving structure  4 , the excavating movement by the working mechanism  5 , and the like. 
     Here,  FIG. 12  shows a basic movement by the drive permission control part  44  when the operating lever  15 A is operated. At a point of T 1 , an operation of the operating lever  15 A by an operator is started and a pilot pressure  37  is generated by this operation. At a point of T 2 , the drive permission determination part  48  of the drive permission control part  44  outputs the drive permission signal En of each of the hydraulic actuators  22  in accordance with the operating state of each of the operating levers  15 A by an operator, based upon the pilot pressure sensor information (the measured data  38  of the pilot pressure  37  thereof). In addition, since the drive permission signal En is “drive permission” from a point of T 2  to a point of T 6 , the pilot pressure selecting part  50  of the drive permission control part  44  outputs the requested boost pilot pressure Pcr from the area limit control part  40  as the boost pilot pressure Pc. At this time, the solenoid valve drive part  53  of the drive permission control part  44  outputs the drive current  45  to the boost proportional solenoid valve  25  based upon the boost pilot pressure Pc. Accordingly, the movement of the hydraulic actuator by the area limit control part  40  is made possible. 
     On the other hand, when the incorrect requested boost pilot pressure Pcr due to the malfunction of the area limit control part  40  is outputted from a point of T 4 , for example, an operator having had uncomfortable feelings to the movement due to this malfunction starts to return all the operating levers  15 A back to the neutral position at a point of T 5 . In this case, at a point of T 6 , the drive permission determination part  48  of the drive permission control part  44  makes the drive permission signal En of all the hydraulic actuators  22  “drive non-permission”. As a result, since the pilot pressure selecting part  50  of the drive permission control part  44  makes all of the boost pilot pressures Pc “zero”, the drive of the boost proportional solenoid valve  25  by the solenoid valve drive part  53  of the drive permission control part  44  stops. Thereby, it is possible to stop the inappropriate movement of the hydraulic actuator  22 . 
     Thus, in the first embodiment, the drive permission determination part  48  determines whether or not to permit the drive of each of the hydraulic actuators  22  in response to an operating state of the operating lever  15 A. In addition, in a case where the drive is permitted, the pilot pressure selecting part  50  drives the control valve  14 A in response to a drive signal (requested boost pilot pressure  43 ) outputted from the area limit control part  40 . On the other hand, in a case where the drive is not permitted, even when the drive signal (requested boost pilot pressure  43 ) is outputted from the area limit control part  40 , the pilot pressure selecting part  50  selects a drive signal not to drive the control valve  14 A. Therefore, when an operator operates the operating lever  15 A, it is possible to permit not only the drive of the hydraulic actuator  22  corresponding to the operating lever  15 A but also the drive of the hydraulic actuator  22  required for moving the machine such that the working mechanism  5  does not deviate from the predetermined spacious area. Together with it, when an operator sets the operating lever  15 A to a neutral position, even when the area limit control part  40  outputs the drive signal (requested boost pilot pressure  43 ) by mistake, since the drive of the hydraulic actuator  22  is not permitted, it is possible to stop the machine. 
     In the first embodiment, it is possible to optionally set one or a plurality of lever operations for permitting the drive to each of the hydraulic actuators  22  by the drive permission setting table  60  in  FIG. 5  and the drive permission setting table  62  in  FIG. 8  corresponding to the drive permission setting section. Therefore, it is possible to set the drive permission suitable for the configuration of the working mechanism  5  and the drive permission suitable for the spacious area for preventing deviation of the working mechanism  5 . 
     The first embodiment is provided with the pilot pressure abnormality detecting part  54  and the abnormality notification part  58  as the requested-boost pilot pressure abnormality detecting section. Therefore, it is possible to perform detection and notification of the control abnormality based upon the drive signal (requested boost pilot pressure  43 ) of each of the hydraulic actuators  22  and the drive permission signal  49  outputted by the drive permission determination part  48 . Accordingly, it is possible to encourage an operator to repair the machine. 
     Next,  FIG. 13  to  FIG. 19  show a second embodiment of the present invention. The second embodiment is characterized in that an operating lever device is configured of an electrical lever device and a pilot pressure upper limit determination part is provided. It should be noted that in the second embodiment, components identical to those in the aforementioned first embodiment are referred to as identical reference numerals, and the explanation is omitted. 
     A plurality of operating lever devices  71  each are configured as an electrical operating lever device, and have an operating lever  71 A to be operated by an operator. Here, the operating lever device  71  is configured as an operating amount measuring section that outputs an operating signal (lever operating amount  72 ) in accordance with an operating amount of each of the operating levers  71 A. The operating lever device  71  has an output side that is connected to a vehicle body control part  73  and a drive permission control part  77  in the main controller  32 . When an operator performs a manual tilt operation (lever operation) of the operating lever  71 A in the operating lever device  71 , an electrical signal (operating signal) corresponding to the lever operating amount  72  is outputted to the vehicle body control part  73  and the drive permission control part  77  in the main controller  32  from the operating lever device  71 . 
     It should be noted that, associated with configuring the operating lever device  71  as the electrical operating lever device, the blockade solenoid valve  30 , the proportional solenoid valve  25  and the other pressure sensor  29  are provided in order from the pilot pump  12 -side on the way of a pilot line  92  connecting between the pilot pump  12  and the control valve  14 A. 
     The vehicle body control part  73  controls a rotational speed of the engine  10 , a flow amount (delivery amount) of the main pump  11  and the like based upon the lever operating amount  72  of the operating lever  71 A, a working state (operating state) of the engine  10 , a delivery pressure of the main pump  11 , a load pressure of each of the hydraulic actuators  22  and the like. Therefore, the vehicle body control part  73  is connected to the operating lever device  71 , the engine  10 , the main pump  11  and each of the hydraulic actuators  22 . In addition, an output side of the vehicle body control part  73  is connected to an area limit control part  75 . The vehicle body control part  73  outputs a target pilot pressure  74  corresponding to the pilot pressure  35  for moving each of the hydraulic actuators  22  to the area limit control part  75 . The target pilot pressure  74  is outputted corresponding to each of the hydraulic actuators  22 . 
     The area limit control part  75  has an input side that is connected to the posture sensor  31  and the vehicle body control part  73  and an output side that is connected to the drive permission control part  77 . The area limit control part  75 , together with the vehicle body control part  73 , is configured as a control section (area limit control section) that outputs a drive signal (requested pilot pressure  76 ) for driving each of the control valves  14 A based upon an operating signal (lever operating amount  72 ) in accordance with the operating amount of each of the operating levers  71 A and a posture signal (detection signal of a state amount concerning the posture) of the posture sensor  31 . That is, the area limit control part  75  estimates the posture of the machine based upon the measured data  41  of the posture sensor  31  in the hydraulic excavator  1 , and predicts a change in the posture of the machine based upon the target pilot pressure  74  outputted from the vehicle body control part  73 . 
     In addition, in a case where there is no possibility that the machine deviates from the predetermined space area, the area limit control part  75  outputs the target pilot pressure  74  to the drive permission control part  77  as the requested pilot pressure  76 . On the other hand, in a case where there is a possibility that the machine deviates from the predetermined space area, the area limit control part  75  adjusts the target pilot pressure  74  to prevent the deviation, and the adjusted target pilot pressure  74  is outputted to the drive permission control part  77  as the requested pilot pressure  76 . The requested pilot pressure  76  is outputted corresponding to each of the hydraulic actuators  22 . 
     The drive permission control part (operation permission control part)  77  has an input side that is connected to the operating lever device  71 , the area limit control part  75  and each of the other pressure sensors  29  and an output side that is connected to each of the proportional solenoid valves  25 , the monitor/operating panel device  16  and the blockade solenoid valve  30 . The drive permission control part  77  recognizes an operating amount of each of the operating levers  71 A by an operator based upon the lever operating amount  72  of the operating lever  71 A, and determines a pilot pressure upper limit value as an upper limit value of the pilot pressure  35  for moving each of the hydraulic actuators  22  in accordance with the lever operating amount  72 . In addition, in a case where the requested pilot pressure  76  in response to the movement of each of the hydraulic actuators  22  is equal to or less than the pilot pressure upper limit value, the drive permission control part  77  outputs the drive current  45  for driving the proportional solenoid valve  25  in accordance with the requested pilot pressure  76  to the proportional solenoid valve  25 . On the other hand, in a case where the requested pilot pressure  76  is higher than the pilot pressure upper limit value, the drive permission control part  77  outputs the drive current  45  for driving the proportional solenoid valve  25  in accordance with the pilot pressure upper limit value to the proportional solenoid valve  25 . 
     Accordingly, even when the incorrect requested pilot pressure  76  is outputted from the area limit control part  75  due to the abnormality of the vehicle body control part  73  or the area limit control part  75 , the movement of each of the hydraulic actuators  22  is controlled to a speed in accordance with the pilot pressure upper limit value determined in accordance with the lever operating amount  72  of an operator. Further, when the operating lever  71 A is in a neutral position, the drive permission control part  77  can make the pilot pressure upper limit value zero in such a manner as not to permit the drives of all the hydraulic actuators  22 . Accordingly, when an operator returns the operating lever  71 A back to the neutral position, the pilot pressure upper limit value becomes zero, thus making it possible to stop an inappropriate movement of the hydraulic actuator  22 . 
     Further, when a requested pilot pressure  76  higher than the pilot pressure upper limit value is outputted from the area limit control part  75 , the drive permission control part  77  can output the abnormality information  46  that the requested pilot pressure  76  is abnormal to the monitor/operating panel device  16 . Accordingly, the abnormality can be notified to an operator. In addition, the drive permission control part  77  can determine the abnormality of the pilot pressure  35  by comparing the pilot pressure  35  detected by the other pressure sensor  29  with a pilot pressure  81  to be described later. In a case where the pilot pressure  35  is determined to be abnormal, the drive permission control part  77  can output the drive current  47  for driving (closing) the blockade solenoid valve  30  to the blockade solenoid valve  30 . Accordingly, the source pressure  34  of the pilot pressure is blocked, thus making it possible to stop the machine. 
     Next, an explanation will be made of the drive permission control part  77  with reference to  FIG. 14  to  FIG. 17 . 
     As shown in  FIG. 14 , the drive permission control part  77  is provided with a pilot pressure upper limit determination part  78 , a pilot pressure selecting part  80 , a solenoid valve drive part  83 , a pilot pressure abnormality detecting part  84  and an abnormality notification part  88 . The pilot pressure upper limit determination part  78  has an input side that is connected to the operating lever device  71  and an output side that is connected to the pilot pressure selecting part  80 . The pilot pressure upper limit determination part  78  is configured as a drive signal upper limit determination section configured to determine and output an upper limit value (pilot pressure upper limit value) of a drive signal (requested pilot pressure  76 ) for driving the control valve  14 A of each of the hydraulic actuators  22  based upon an operating signal (lever operating amount  72 ) in accordance with the operating amount of each of the operating levers  71 A. That is, the pilot pressure upper limit determination part  78  determines a pilot pressure upper limit value of each of the hydraulic actuators  22  according to the operating state of each of the operating levers  71 A by an operator based upon the lever operating amount  72 . In addition, the pilot pressure upper limit determination part  78  outputs the pilot pressure upper limit value  79  of each of the hydraulic actuators  22  to the pilot pressure selecting part  50 . 
     The pilot pressure selecting part  80  has an input side that is connected to the area limit control part  75  and the pilot pressure upper limit determination part  78  and an output side that is connected to the solenoid valve drive part  83 , the pilot pressure abnormality detecting part  84  and the abnormality notification part  88 . The pilot pressure selecting part  80  is configured as a drive signal selecting section configured to select a drive signal (requested pilot pressure  76 ) in such a way as to drive the control valve  14 A by the drive signal (requested pilot pressure  76 ) to the hydraulic actuator  22  the drive signal (requested pilot pressure  76  from the area limit control part  75 ) of which is equal to or less than the pilot pressure upper limit value  79  determined in the pilot pressure upper limit determination part  78 , and in such a way as to drive the control valve  14 A by the pilot pressure upper limit value  79  to the hydraulic actuator  22  the drive signal (requested pilot pressure  76 ) of which is beyond the pilot pressure upper limit value  79  determined in the pilot pressure upper limit determination part  78 . 
     That is, the pilot pressure selecting part  80  selects any of the requested pilot pressure  76  and the pilot pressure upper limit value  79  of each of the hydraulic actuators  22  as the pilot pressure  81  in accordance with the pilot pressure upper limit value  79 . In addition, the pilot pressure selecting part  80  outputs the pilot pressure  81  to the solenoid valve drive part  83  and the pilot pressure abnormality detecting part  84 . 
     Further, the pilot pressure selecting part  80 , when the requested pilot pressure  76  is beyond the pilot pressure upper limit value  79 , outputs requested-pilot pressure abnormality information  82  that the requested pilot pressure  76  is abnormal to the abnormality notification part  88 . That is, the pilot pressure selecting part  80  is configured as an abnormality detecting section (requested-pilot pressure abnormality detecting section) configured to detect control abnormality based upon the drive signal (requested pilot pressure  76 ) of each of the hydraulic actuators  22  and the upper limit value (pilot pressure upper limit value  79 ) of the drive signal determined in the pilot pressure upper limit determination part  78 . It should be noted that the processing in  FIG. 18  to be executed in the pilot pressure selecting part  80  will be explained later. 
     The solenoid valve drive part  83  has an input side that is connected to the pilot pressure selecting part  80  and an output side that is connected to the proportional solenoid valve  25 . The solenoid valve drive part  83  outputs the drive current  45  of the proportional solenoid valve  25  to the boost proportional solenoid valve  25  based upon the pilot pressure  81  from the pilot pressure selecting part  80 . Thereby, the proportional solenoid valve  25  opens in response to the drive current  45  to supply the pilot pressure  35  corresponding to the pilot pressure  81  to the pilot part of the control valve  14 A. 
     The pilot pressure abnormality detecting part  84  has an input side that is connected to the pilot pressure selecting part  80  and each of the other pressure sensors  29  and an output side that is connected to the abnormality notification part  88  and the blockade solenoid valve  30 . The pilot pressure abnormality detecting part  84  compares the measured data of the pilot pressure  35  as pilot pressure sensor information  85  of each of the other pressure sensors  29  with the pilot pressure  81  from the pilot pressure selecting part  80  to detect the abnormality of the pilot pressure  35 . The pilot pressure abnormality detecting part  84  outputs pilot pressure abnormality information  86  that the pilot pressure  35  is abnormal to the abnormality notification part  88  in a case where the abnormality of the pilot pressure  35  is detected. 
     Together with it, the pilot pressure abnormality detecting part  84  outputs a pilot pressure blocking request  87  as a command signal for blocking the pilot pressure (source pressure  34  thereof) to the blockade solenoid valve  30 . That is, the pilot pressure abnormality detecting part  84  is configured as another abnormality detecting section (pilot pressure abnormality detecting section) configured to detect the control abnormality based upon a drive signal (pilot pressure  81 ) selected in the pilot pressure selecting part  80  and an actual drive signal (pilot pressure  35 ) supplied to the control valve  14 A, and as a drive signal stopping section configured to block a drive signal (pilot pressure) to the control valve  14 A at the time of detecting the abnormality. It should be noted that the processing executed in the pilot pressure abnormality detecting part  84  is similar to the processing in  FIG. 11  executed in the pilot pressure abnormality detecting part  54  in the first embodiment, other than a point where “boost pilot pressure Pc” is “pilot pressure Pc”. 
     The abnormality notification part  88  has an input side that is connected to the pilot pressure selecting part  80  and the pilot pressure abnormality detecting part  84  and an output side that is connected to the monitor/operating panel device  16 . The abnormality notification part  88 , when the control abnormality is detected by the pilot pressure selecting part  80  and/or the pilot pressure abnormality detecting part  84 , is configured as an abnormality notification section configured to notify the abnormality. That is, the abnormality notification part  88  outputs the abnormality information  46  concerning the occurrence of the abnormality and corresponding to the content of the abnormality to the monitor/operating panel device  16  based upon the requested-pilot pressure abnormality information  82  from the pilot pressure selecting part  80  and/or the pilot pressure abnormality information  86  from the pilot pressure abnormality detecting part  84 . 
     Here, the pilot pressure upper limit determination part  78  can preliminarily set a pilot pressure upper limit value for permitting the movement of each of the hydraulic actuators  22  for each lever operation of an operator.  FIG. 15  is a pilot pressure upper limit value setting table  90  that shows an example of a pilot pressure upper limit value for permitting the movement of each of the hydraulic actuators  22  for each lever operation in a matrix. “0” in  FIG. 15  indicates that the pilot pressure upper limit value is 0, which means not to move the hydraulic actuator  22 . “Ca” and “Cb” in  FIG. 15 , as shown in  FIG. 17 , indicate that an upper limit value of the pilot pressure of each varies in accordance with the lever operating amount. As shown in  FIG. 17 , both “Ca” and “Cb” are in a dead zone when the lever operating amount is in a range of 0 to v 1 . When the lever operating amount is in a range of v 1  to v 2 , the pilot pressure upper limit value increases (for example, increases proportionally) with an increase of the lever operating amount in both “Ca” and “Cb”. In addition, in v 2 , the maximum value of the pilot pressure upper limit value, that is, “Ca” reaches Ppa 2 , and “Cb” reaches Ppb 2 . 
     The pilot pressure upper limit determination part  78  outputs the greatest value out of the pilot pressure upper limit values in response to the lever operation for each movement of each of the hydraulic actuators  22  as the pilot pressure upper limit value  79 , based upon the pilot pressure upper limit setting table  90  in a case where one or more of the lever operations are performed. 
     When an operator performs the arm pulling operation and the bucket excavating operation, as shown in  FIG. 16  the pilot pressure upper limit determination part  78  determines the pilot pressure upper limit value  79  of each of the hydraulic actuators  22  in accordance with the lever operating amount of each of the arm pulling and the bucket excavating. Specifically, when the arm pulling operating amount is indicated at v 3  and the bucket excavating operating amount is indicated at v 4 , the pilot pressure upper limit value of the arm pulling is Ppa 3  from “Ca” in  FIG. 17 , and the pilot pressure upper limit value of the bucket excavating is Ppa 4  from “Ca” in  FIG. 17 . On the other hand, the pilot pressure upper limit value of the boom raising is Ppa 3  as the greatest value of Ppa 3  and Ppb 4  from “Ca” and “Cb” in  FIG. 17 . Further, the pilot pressure upper limit value of the other operation becomes zero. 
     Accordingly, the movement of the hydraulic actuator  22  in response to the boom raising movement by the area limit control part  75  is made possible even without the boom raising operation by an operator. In addition, even when the area limit control part  75  outputs the incorrect requested pilot pressure  76  due to malfunction of the area limit control part  75 , the inappropriate boom raising movement can be suppressed to a speed in accordance with the lever operating amount of an operator. Further, when the operator returns the operating lever  71 A back to the neutral position, it is possible to stop the inappropriate boom raising movement. 
     Thus, the pilot pressure upper limit determination part  78  is provided with the pilot pressure upper limit value setting table  90  as shown in  FIG. 15  and a characteristic diagram  91  of the lever operating amount and the pilot pressure upper limit value as shown in  FIG. 17 . The pilot pressure upper limit value setting table  90  represents a corresponding relation between the lever operation performed by an operator and the pilot pressure upper limit value of each of the lever operations in response thereto. The characteristic diagram  91  of the lever operating amount and the pilot pressure upper limit value represents a corresponding relation between the lever operation amount and the pilot pressure upper limit value. In addition, the pilot pressure upper limit value setting table  90  as shown in  FIG. 15  is configured as a drive signal upper limit value setting section configured to determine an upper limit value of a drive signal (pilot pressure) in accordance with the operating amount of each of the lever operations to each of the hydraulic actuators  22 . 
     It should be noted that the drive signal upper limit value setting section is only required to set the corresponding relation between the lever operation performed by an operator and the pilot pressure upper limit value of each of the lever operations in response thereto, and is not limited to the table (matrix) as shown in  FIG. 15 . In addition, the pilot pressure upper limit value setting table  90  and the characteristic diagram  91  of the lever operating amount and the pilot pressure upper limit value are not limited to those in  FIG. 15  and in  FIG. 17 , but various kinds of the drive signal upper limit value setting tables (the corresponding relation between the lever operation performed by an operator and the pilot pressure upper limit value of each of the lever operations in response thereto) and the characteristic diagram (corresponding relation between the lever operating amount and the pilot pressure upper limit value) may be set in response to the limit control of the area limit control part  75 . 
     Next,  FIG. 18  shows the control processing that is executed in the pilot pressure selecting part  80 . The control processing in  FIG. 18  is repeatedly executed in a predetermined control cycle during power supply to the main controller  32  (pilot pressure selecting part  80 ), for example. 
     When the control processing of the pilot pressure selecting part  80  starts, at step S 31 , the pilot pressure selecting part  80  acquires the requested pilot pressure  76  outputted from the area limit control part  75 , that is, a requested pilot pressure Pcr. At a subsequent step S 32 , the pilot pressure upper limit value  79  corresponding to the upper limit value determination result outputted from the pilot pressure upper limit determination part  78 , that is, a pilot pressure upper limit value Pp is acquired. At step  33 , it is determined whether or not the requested pilot pressure Pcr is equal to or less than the pilot pressure upper limit value Pp. 
     At S 33 , in a case where “YES” determination is made, that is, in a case where it is determined that the requested pilot pressure Pcr is equal to or less than the pilot pressure upper limit value Pp, the process goes to S 34 . At S 34 , the requested pilot pressure Pcr is defined as the pilot pressure Pc. That is, the pilot pressure  81  is outputted as the pilot pressure Pc (=Pcr) to the solenoid valve drive part  83  and the pilot pressure abnormality detecting part  84 , and the process returns (the process is back to START through RETURN, and the processing after S 31  is repeated). 
     On the other hand, at S 33 , in a case where “NO” determination is made, that is, in a case where it is determined that the requested pilot pressure Pcr is greater than the pilot pressure upper limit value Pp, the process goes to S 35 . At S 35 , the requested pilot pressure Pcr is defined as the pilot pressure upper limit value Pp. That is, the pilot pressure  81  is outputted as the pilot pressure Pc (=Pb) to the solenoid valve drive part  83  and the pilot pressure abnormality detecting part  84 . At subsequent S 6 , the requested-pilot pressure abnormality information  82  as abnormality information that the requested pilot pressure Pcr is abnormal is outputted to the abnormality notification part  88 , and the process returns. These processes, that is, the processing to be executed in the pilot pressure selecting part  80  is executed to the movement in each of the hydraulic actuators  22 . 
     Here,  FIG. 19  shows a basic movement by the drive permission control part  77  when the operating lever  71 A is operated. At a point of T 1 , an operation of the operating lever  71 A by an operator is started. From a point of T 2 , the pilot pressure upper limit value Pp outputted from the pilot pressure upper limit determination part  78  in the drive permission control part  77  increases with an increase of the operating amount of the operating lever  71 A. In addition, from a point of T 2  to a point of T 5 , since the requested pilot pressure Pcr from the area limit control part  75  is equal to or less than the pilot pressure upper limit value Pp, the pilot pressure selecting part  80  of the drive permission control part  77  outputs the requested pilot pressure Pcr from the area limit control part  75  as the pilot pressure Pc. At this time, the solenoid valve drive part  83  of the drive permission control part  77  outputs the drive current  45  to the proportional solenoid valve  25  based upon pilot pressure Pc. Accordingly, the movement of the hydraulic actuator  22  by the vehicle body control part  73  and the area limit control part  75  is made possible. 
     On the other hand, when the incorrect requested pilot pressure Pcr due to the malfunction of the vehicle body control part  73  or the area limit control part  75  is outputted from a point of T 4 , and when the requested pilot pressure Pcr is greater than the pilot pressure upper limit value Pp from a point of T 5 , the pilot pressure selecting part  80  of the drive permission control part  77  outputs the pilot pressure upper limit value Pp as the pilot pressure Pc. Accordingly, at a point of T 6  from a point of T 5 , the pilot pressure can be suppressed to the pilot pressure Pc in accordance with the lever operating amount. Further, when an operator starts to return the operating lever  71 A back to the neutral position at a point of T 6 , at a point of T 7 , the pilot pressure upper limit value Pp in the pilot pressure upper limit determination part  78  of the drive permission control part  77  becomes zero. As a result, since the pilot pressure selecting part  80  of the drive permission control part  77  makes the pilot pressure Pc zero, the drive of the proportional solenoid valve  25  by the solenoid valve drive part  83  of the drive permission control part  77  stops. Accordingly, it is possible to decelerate and stop the inappropriate movement of the hydraulic actuator  22 . 
     The second embodiment is configured to control the pilot pressure Pc to be equal to or less than the pilot pressure upper limit value Pp by the pilot pressure upper limit determination part  78  as described above, and a basic operation thereof does not differ particularly from that of the aforementioned first embodiment. 
     Particularly, in the second embodiment, the pilot pressure upper limit determination part  78  determines the upper limit value of the drive signal (requested pilot pressure  76 ) for driving the control valve  14 A of each of the hydraulic actuators  22  in accordance with the operating amount of the operating lever  71 A. In addition, the pilot pressure selecting part  80  drives the control valve  14 A in response to the drive signal (requested pilot pressure  76 ) outputted from the area limit control part  75  to the hydraulic actuator  22  the drive signal (requested pilot pressure  76 ) of which is equal to or less than the upper limit value. On the other hand, the pilot pressure selecting part  80  selects the drive signal (requested pilot pressure  76 ) in such a manner as to drive the control valve  14 A with the upper limit value (pilot pressure upper limit value  79 ) to the hydraulic actuator  22  the drive signal (requested pilot pressure  76 ) of which is beyond the upper limit value. Therefore, when an operator operates the operating lever  71 A, it is possible to permit not only the drive of the hydraulic actuator  22  corresponding to the operating lever  71 A but also the drive of the hydraulic actuator  22  required for moving the machine such that the working mechanism  5  does not deviate from the predetermined spacious area. Together with it, even when the incorrect drive signal (requested pilot pressure  76 ) is outputted from the area limit control part  75 , since the drive signal is suppressed to a drive signal in accordance with the lever operating amount  72  by an operator, that is, the pilot pressure upper limit value  79 , a speed change of the machine can be suppressed. Further, when an operator sets the operating lever  71 A to a neutral position, even when the area limit control part  75  outputs the incorrect drive signal (requested pilot pressure  76 ), the drive signal is suppressed to zero of the pilot pressure upper limit value  79 . Accordingly, the drive of the hydraulic actuator  22  is not permitted, thus making it possible to stop the machine. 
     In the second embodiment, it is possible to set the upper limit value (pilot pressure upper limit value  79 ) of the drive signal in accordance with the operating amount of each of the lever operations to each of the hydraulic actuators  22  by the pilot pressure upper limit value setting table  90  in  FIG. 15  corresponding to the drive signal upper limit setting section. Therefore, it is possible to set the upper limit value of the drive signal suitable for the configuration of the working mechanism  5  and the upper limit value of the drive signal suitable for the spacious area for preventing deviation of the working mechanism  5 . 
     The second embodiment is provided with the pilot pressure selecting part  80  and the abnormality notification part  88  as the requested-pilot pressure abnormality detecting section. 
     Therefore, it is possible to perform detection and notification of the control abnormality based upon the drive signal (requested pilot pressure  76 ) of each of the hydraulic actuators  22  and the upper limit value (pilot pressure upper limit value  79 ) outputted by the pilot pressure upper limit determination part  78 . Thereby, it is possible to encourage an operator to repair the machine. 
     It should be noted that the aforementioned first embodiment is explained by taking a case where the vehicle body control part  36 , the area limit control part  40  and the drive permission control part  44  are mounted in the single main controller  32 , as an example. However, the present invention is not limited thereto, but, for example, the area limit control part  40  and the drive permission control part  44  may be mounted in a controller different from the main controller  32  in which the vehicle body control part  36  is mounted. In addition, the vehicle body control part  36 , the area limit control part  40  and the drive permission control part  44  may be respectively mounted in different controllers. This configuration can be applied likewise to the second embodiment. 
     The aforementioned first embodiment is explained by taking a case of moving the boom  5 A in the raising direction to prevent excavating the side deeper than the target surface  61  and a case of moving the arm  5 B in the pushing direction to prevent the bucket  5 C from entering the interference prevention area  63  as the control performed in the area limit control part  40 , as an example. However, the present invention is not limited thereto, but for example, the control section (area limit control section) may be configured, in addition to the above, to perform various kinds of control to prevent the machine from deviating from the predetermined space area, such as avoidance of collision of the machine upper side with facilities in the working site and the like. This configuration can be applied likewise to the second embodiment. 
     The aforementioned first embodiment is explained by taking a case where the hydraulic actuator  22  is operated using the operating lever  15 A, as an example. However, the present invention is not limited thereto, but, for example, the hydraulic actuator  22  may be operated using various kinds of operating devices such as an operating pedal or an operating stick and the like. That is, the operating lever includes various kinds of operating devices. This configuration can be applied likewise to the second embodiment. 
     The aforementioned first embodiment is explained by taking a case where the drive signal for driving the control valve  14 A is adopted as the pilot pressure (hydraulic pressure), as an example. However, the present invention is not limited thereto, but, for example, various kinds of drive signals other than the hydraulic pressure may be used, such as adopting a solenoid valve as the control valve and adopting an electrical signal as the drive signal and the like. This configuration can be applied likewise to the second embodiment. 
     The aforementioned first embodiment is explained by taking a case where the drive source of the revolving device  3  is configured of the revolving hydraulic motor  3 A, as an example. However, the present invention is not limited thereto, but, the drive source of the revolving device may be configured of, for example, a hydraulic motor (revolving hydraulic motor) and an electric motor (revolving electric motor). In addition, the drive source of the revolving device may be configured of an electric motor (revolving electric motor) only. This configuration can be applied likewise to the second embodiment. 
     Each of the aforementioned embodiments is explained by taking a case where the hydraulic excavator  1  is adopted as the construction machine, as an example. However, the present invention is not limited thereto, for example, but the present invention may be widely applied to various types of construction machines such as a wheel loader. Further, each of the embodiments is disclosed as only an example and a partial replacement or a combination of the configurations in the different embodiments can be made without mentioning. 
     According to the above embodiments, it is possible to stop the machine by setting the operating lever to a neutral position whether the control section is normal or not, and it is possible to control the working mechanism from deviating from the predetermined spacious area. 
     (1) That is, according to the embodiment, it is configured to includes the drive permission determination section and the drive signal selecting section. In addition, the drive signal selecting section is configured to select the drive signal in such a manner as not to drive the control valve to the hydraulic actuator the drive of which is not permitted by the drive permission determination section. In this case, the drive permission determination section can prevent the drives of all the hydraulic actuators from being permitted when the operating lever is in the neutral position. Accordingly, when an operator sets the operating lever to the neutral position, the drive permission determination section selects the drive signal not to drive the control valve even if an abnormal drive signal is outputted. As a result, it is possible to stop the machine by setting the operating lever to the neutral position, without mentioning when there is no presence of the abnormal drive signal, and even if there is presence of the abnormal drive signal. 
     On the other hand, when the operating lever is operated from the neutral position, the drive permission determination section can permit the drive of the hydraulic actuator required for controlling the working mechanism from deviating from the predetermined spacious area to the operating lever. Accordingly, even if the abnormal drive signal (for example, drive signal other than the drive signal for controlling the working mechanism from deviating from the predetermined spacious area) is present, the drive signal selecting section is configured to select the drive signal to the hydraulic actuator the drive of which is permitted by the drive permission determination section without selecting the abnormal drive signal. Asa result, it is possible to control the working mechanism from deviating from the predetermined spacious area, without mentioning when there is no presence of the abnormal drive signal, and also even if there is presence of the abnormal drive signal. 
     (2) According to the embodiment, the drive permission determination section is configured to include the drive permission setting section. In this case, the drive permission setting section may be set as the corresponding relation between the lever operation and the movement of the actuator the drive of which is permitted to the lever operation. That is, the drive permission setting section may set the drive permission suitable for the configuration of the working mechanism and/or the drive permission suitable for the spacious area for preventing the deviation of the working mechanism. Accordingly, the drive permission determination section can appropriately and stably determine whether to permit the drive of each of the hydraulic actuators. 
     (3) According to the embodiment, it is configured to further include the abnormality detecting section and the abnormality notification section. Accordingly, it is possible to notify an operator of the abnormality and further, to automatically stop the machine. Asa result, it is possible to encourage an operator to repair the machine. 
     (4) According to the embodiment, it is configured to include the drive signal upper limit determination section and the drive signal selecting section. In addition, the drive signal selecting section selects the drive signal in such a manner as to drive the control valve with the upper limit value to the hydraulic actuator the drive signal of which is beyond the upper limit value determined in the drive signal upper limit determination section. In this case, the drive signal upper limit determination section can make the upper limit values of the drive signals to all the hydraulic actuators zero when the operating lever is in the neutral position. Accordingly, when an operator sets the operating lever to the neutral position, the drive signal selecting section selects the drive signal as zero that is the upper limit value even if there is present the abnormal drive signal. As a result, it is possible to stop the machine by setting the operating lever to the neutral position, without mentioning when there is no presence of the abnormal drive signal, and even if there is presence of the abnormal drive signal. 
     On the other hand, when the operating lever is operated from the neutral position, the drive signal upper limit determination section can determine the upper limit value of the drive signal to be capable of driving the hydraulic actuator required for controlling the working mechanism from deviating from the predetermined spacious area to the lever operation. 
     Accordingly, even if there is present the abnormal drive signal (for example, drive signal exceeding the upper limit value of the drive signal for controlling the working mechanism from deviating from the predetermined spacious area), the drive signal selecting section is configured to select the upper limit value of the drive signal determined by the drive signal upper limit determination section. As a result, it is possible to control the working mechanism from deviating from the predetermined spacious area, without mentioning when there is not present the abnormal drive signal, and also even if there is present the abnormal drive signal. 
     (5) According to the embodiment, the drive signal upper limit determination section is configured to include the drive signal upper limit value setting section. In this case, the drive signal upper limit determination section may be set as the corresponding relation between the lever operation and the upper limit value of the drive signal to the actuator the drive of which is permitted to the lever operation. That is, the drive signal upper limit determination section may set the upper limit value of the drive signal suitable for the configuration of the working mechanism and/or the upper limit value of the drive signal suitable for the spacious area for preventing the deviation of the working mechanism. Accordingly, the drive signal upper limit determination section can appropriately and stably determine the upper limit value to each of the hydraulic actuators. 
     (6) According to the embodiment, it is configured to further include the abnormality detecting section and the abnormality notification section. Accordingly, it is possible to notify an operator of the abnormality and further, to automatically stop the machine. Asa result, it is possible to encourage an operator to repair the machine. 
     DESCRIPTION OF REFERENCE NUMERALS 
       1 : Hydraulic excavator (Construction machine) 
       2 : Lower traveling structure (Machine) 
       2 E: Traveling hydraulic motor (Hydraulic actuator) 
       3 : Revolving device (Machine) 
       3 A: Revolving hydraulic motor (Hydraulic actuator) 
       4 : Upper revolving structure (Machine) 
       5 : Working mechanism (Machine) 
       5 D: Boom cylinder (Hydraulic actuator) 
       5 E: Arm cylinder (Hydraulic actuator) 
       5 F: Bucket cylinder (Hydraulic actuator) 
       14 : Control valve device 
       14 A: Control valve 
       15 : Operating lever device 
       15 A: Operating lever 
       28 : Pressure sensor (Operating amount measuring section) 
       31 : Posture sensor (Posture measuring section) 
       32 : Main controller 
       40 ,  75 : Area limit control part (Control section) 
       48 : Drive permission determination part (Drive permission determination section) 
       50 ,  80 : Pilot pressure selecting part (Drive signal selecting section, Abnormality detecting section) 
       58 ,  88 : Abnormality notification part (Abnormality notification section) 
       60 ,  62 : Drive permission setting table (Drive permission setting section) 
       71 : Operating lever device (Operating amount measuring section) 
       71 A: Operating lever 
       73 : Vehicle body control part (Control section) 
       78 : Pilot pressure upper limit determination part (Drive signal upper limit determination section) 
       90 : Pilot pressure upper limit value setting table (Drive signal upper limit setting section)