JP2006308073A - Hydraulic drive system for construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic drive system having simple and inexpensive construction for detecting the malfunction of a solenoid proportional pressure reducing valve and stopping a hydraulic actuator. <P>SOLUTION: A controller 26 inputs operation signals VL1-VL4 from electric lever devices 20, 21, an instruction signal GL from a gate lock clever switch 22, and a monitoring signal EL from a pressure sensor 25 and outputs a drive signal to the solenoid proportional pressure reducing valve 10a, or 10b-12a or 12b. It also determines the malfunction in accordance with signals VL1, VL2; VL3, VL4, GL, EL and outputs a signal for changing over a solenoid selector valve 24. The pressure sensor 25 is connected at its upstream side to a pilot pump 3 and at its downstream side to a tank. It detects pressure on the upstream side of a hydraulic signal line 33 which is cut off by the movement of spools of control valves 7-9 to detect that the spool of any of the control valves 7-9 is in an operated condition and changes over the solenoid selector valve 24 to stop the actuator. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a construction machine such as a hydraulic excavator, and more particularly to a hydraulic drive system for a construction machine that detects an abnormality in an electromagnetic proportional pressure reducing valve in a hydraulic drive system including an electric lever device.

  For example, a hydraulic excavator, which is one of construction machines, includes a lower traveling body, an upper swinging body that is swingably provided on the lower traveling body, and a boom, an arm, and a bucket that are connected to the upper swinging body so as to be able to be lifted and lowered. And an articulated front work machine including a work tool such as the above. Each component of the lower traveling body, the upper swing body, and the front work machine is hydraulically driven by a hydraulic drive system. This hydraulic drive system generally includes a prime mover such as an engine, a hydraulic pump driven by the prime mover, and a boom hydraulic cylinder that drives the boom, arm, and work implement by pressure oil discharged from the hydraulic pump, A plurality of hydraulic actuators including a hydraulic cylinder for arm and a hydraulic cylinder for bucket, a plurality of control valves for controlling the flow of pressure oil supplied from the hydraulic pump to each of the hydraulic actuators, and manual operation of the hydraulic actuator Operating means. The hydraulic drive system includes, for example, a pilot pump driven by the prime mover, and an electromagnetic valve (electromagnetic proportional pressure reducing valve) that controls the pilot pressure to the control valve in accordance with an operation amount (electric signal) of the operation means. And a pilot circuit.

  In such a hydraulic drive system, when an abnormality occurs in the electromagnetic proportional pressure reducing valve, the hydraulic actuator can be controlled to be stopped or controlled at a predetermined low speed, for example, as described in JP-A-7-19207 There is a drive control device for hydraulic machines. This drive control device is provided with a pressure sensor between an electromagnetic proportional pressure reducing valve and a control valve in a pilot circuit, and a pilot pressure signal detected by the pressure sensor and an operation signal (electric signal) output from the operation means. In comparison, when the pilot pressure signal and the operation signal are not equal, it is determined that the electromagnetic proportional pressure reducing valve is abnormal. According to this, even when the electromagnetic proportional pressure reducing valve malfunctions due to the catch of foreign matter, the operation signal of the operating means is a signal corresponding to the stop of the hydraulic actuator, whereas the pilot pressure detected by the pressure sensor is Since the signal is a signal corresponding to the driving of the hydraulic actuator, an abnormality can be detected immediately. Accordingly, it is possible to quickly take measures such as stopping the prime mover and stopping all hydraulic actuators.

Japanese Patent Laid-Open No. 7-19207

  In the hydraulic drive system, for example, some metal pieces of mechanical parts constituting the hydraulic drive system may be peeled off into the hydraulic circuit, or dust in the atmosphere may be mixed into the hydraulic circuit. At this time, when foreign matter such as these metal pieces or dust enters the inside of the electromagnetic proportional pressure reducing valve, for example, the drive portion of the electromagnetic proportional pressure reducing valve may be caught by the foreign matter and cause malfunction. That is, when such a malfunction occurs, for example, in an electromagnetic proportional pressure reducing valve that controls the control valve of the boom hydraulic cylinder, the control valve is controlled from the electromagnetic proportional pressure reducing valve even if the operator operates the operating means to stop the boom. F pilot pressure continues to be output. As a result, the boom hydraulic cylinder may continue to operate, and the front work machine may operate against the operator's intention.

  In addition, even when foreign matters such as metal pieces or dust enter the control valve, the drive portion (spool) of the control valve may be caught in the same manner as the electromagnetic proportional pressure reducing valve, resulting in malfunction. is there. In this case, even if the operator operates the operating means so as to stop the hydraulic actuator corresponding to the control valve, the electromagnetic proportional pressure reducing valve is in the shut-off position, and the spool does not move even if the pilot pressure to the control valve is shut off. It may be difficult to stop the hydraulic actuator without returning to the neutral position while being caught.

  According to the technique described in Japanese Patent Application Laid-Open No. 7-19207, when an operation failure of the electromagnetic proportional pressure reducing valve occurs due to the catch of foreign matter, the operation signal of the operation means is compared with the pilot pressure signal detected by the pressure sensor. Thus, the abnormality can be detected, and a response such as stopping the prime mover and stopping all hydraulic actuators can be taken quickly.

  However, in the technique described in Japanese Patent Laid-Open No. 7-19207, since a pressure sensor is provided between the electromagnetic proportional pressure reducing valve and the control valve in the pilot circuit, two pressure sensors are required for one control valve. Thus, the number of pressure sensors increases according to the number of control valves, the number of pressure sensors is large, and the system becomes extremely complicated and expensive.

  Further, when a foreign matter such as a small metal piece or dust enters the control valve and the control valve malfunctions, when the operator operates the operating means to stop the hydraulic actuator corresponding to the control valve, Since the pilot pressure signal detected by the pressure sensor and the operation signal output from the operation means are equivalent signals corresponding to the stop of the hydraulic actuator, it is difficult to detect such an abnormality of the control valve.

  A first object of the present invention is to provide a hydraulic drive system for a construction machine that can detect an abnormality of an electromagnetic proportional pressure reducing valve and stop a hydraulic actuator, and has a simple and inexpensive system configuration.

  A second object of the present invention is to provide a hydraulic drive system for a construction machine that can detect an abnormality of not only an electromagnetic proportional pressure reducing valve but also a control valve and stop a hydraulic actuator.

  (1) In order to achieve the first and second objects, the present invention includes a prime mover, a hydraulic pump driven by the prime mover, a plurality of hydraulic actuators for driving a driven body, and the hydraulic pump. A plurality of hydraulic pilot type control valves that respectively control the flow of pressure oil to the plurality of hydraulic actuators, and a plurality of electromagnetic proportionalities that generate pilot pressures to the plurality of control valves based on the pilot pressure of a pilot hydraulic source A pressure reducing valve and a plurality of electric lever devices that command the operations of the plurality of hydraulic actuators are provided, and corresponding ones of the plurality of electromagnetic proportional pressure reducing valves are controlled in accordance with respective operation signals of the plurality of electric lever devices. In the hydraulic drive system for a construction machine, the operation detection means for detecting whether any one of the plurality of control valves is in an operating state; An abnormality determination unit that determines abnormality based on operation signals of a plurality of electric lever devices and a detection result of the motion detection unit, and an actuator stop that stops the plurality of hydraulic actuators when the abnormality determination unit determines that there is an abnormality And a hydraulic signal line connected upstream to the pilot hydraulic pressure source, connected downstream to the tank, and shut off by movement of the spools of the plurality of control valves, and the hydraulic signal line. And a pressure sensor for detecting the pressure on the upstream side.

  In the present invention configured as described above, the operation detection unit detects whether any spool of the control valve is in an operating state, and the abnormality determination unit detects the operation signal of the electric lever device and the operation detection unit. Abnormality is determined based on the result. For example, when it is detected by the operation signal of the electric lever device that all the electric lever devices are not operated by the operator, and the operation detecting means detects that the spool of one of the control valves is in an operating state. In addition, there is some abnormality in the electromagnetic proportional pressure reducing valve that is driven according to the operation signal and should control the pilot pressure, or the control valve that is driven according to the pilot pressure and should control the flow of pressure oil to the hydraulic actuator It can be seen that there is some kind of abnormality.

  Accordingly, when the abnormality determining means determines that there is an abnormality, the actuator stopping means can be operated to stop the hydraulic actuator.

  In the present invention, the operation detecting means includes a hydraulic signal line connected to the pilot hydraulic power source on the upstream side and connected to the tank on the downstream side, and shut off by the movement of the spools of the plurality of control valves. Since it has a configuration having a pressure sensor for detecting the pressure on the upstream side, even if any of the plurality of control valves or the electromagnetic proportional pressure reducing valves malfunctions, the operating state can be detected by one pressure sensor. For this reason, the system configuration is extremely simple and inexpensive.

  In addition, since the operation detection means consisting of the hydraulic signal line and the pressure sensor detects the operating state of the control valve itself, not only when an abnormality occurs in the electromagnetic proportional pressure reducing valve, but also when an abnormality occurs in the control valve The abnormality determining means can determine the abnormality and can stop the hydraulic actuator by operating the actuator stopping means.

  (2) In the above (1), preferably, the abnormality determining means indicates that all the operation signals of the plurality of electric lever devices indicate a non-operating state, and the operation detecting means selects any one of the plurality of control valves. When it is detected that the spool is operating, it is determined that there is an abnormality.

  Thereby, the abnormality of the electromagnetic proportional pressure reducing valve or the control valve can be detected.

  (3) In the above (1), preferably, the actuator stop means is a switching valve capable of communicating / blocking a pilot pipeline from the pilot hydraulic power source to the plurality of electromagnetic proportional pressure reducing valves, and the abnormality determination. Means for controlling the switching valve and shutting off the pilot line when the means is determined to be abnormal.

  As a result, when the electromagnetic proportional pressure reducing valve malfunctions, the abnormality determining means determines that there is an abnormality and shuts off the pilot line, so that the supply of pressure oil from the pilot hydraulic power source to the electromagnetic proportional pressure reducing valve is cut off. Then, the control valve that has been operated is returned to the neutral position, and the operation of all the hydraulic actuators is stopped.

  (4) Furthermore, in the above (1), preferably, the actuator stopping means is means for stopping the prime mover when the abnormality determining means determines that there is an abnormality.

  As a result, not only when the electromagnetic proportional pressure reducing valve malfunctions, but also when the control valve malfunctions, the abnormality determination means determines the abnormality and stops the prime mover. As a result, the operation of all the hydraulic actuators stops.

  (5) In the above (1), preferably, a switching valve capable of communicating / blocking a pilot pipeline from the pilot hydraulic power source to the plurality of electromagnetic proportional pressure reducing valves, and an instruction for instructing switching of the switching valve And the actuator stopping means, even when the instruction means instructs the switching of the switching valve to communicate the pilot pipeline, when the abnormality determination means determines that an abnormality, It is means for controlling the switching valve and blocking the pilot pipeline.

  As a result, for example, an indication means such as a gate lock lever switch and its switching valve are provided. Regardless of the indication state of the indication means, an abnormality occurs in the electromagnetic proportional pressure reducing valve or the control valve, and the abnormality determination means determines that it is abnormal. In this case, the switching valve can be controlled to shut off the pilot line and stop the hydraulic actuator. Further, since the hydraulic actuator is stopped using a switching valve provided for an indicating means such as a gate lock lever switch, the system configuration is further simplified and inexpensive.

  (6) In order to achieve the first and second objects, the present invention provides a prime mover, a hydraulic pump driven by the prime mover, a plurality of hydraulic actuators for driving a driven body, and the hydraulic pressure A plurality of hydraulic pilot-type control valves that respectively control the flow of pressure oil from the pump to the plurality of hydraulic actuators, and a plurality of pilot pressures to the plurality of control valves based on the pilot pressure of a pilot hydraulic power source An electromagnetic proportional pressure reducing valve and a plurality of electric lever devices that command the operations of the plurality of hydraulic actuators, and corresponding to the plurality of electromagnetic proportional pressure reducing valves according to respective operation signals of the plurality of electric lever devices In the hydraulic drive system of a construction machine that controls the operation, an operation detecting means for detecting whether any of the spools of the plurality of control valves is in an operating state An abnormality determining means for determining an abnormality based on an operation signal of the plurality of electric lever devices and a detection result of the motion detecting means, and a means for stopping the hydraulic actuator when the abnormality determining means determines an abnormality. The operation detecting means includes a hydraulic signal line having an upstream side connected to the pilot hydraulic pressure source, a downstream side connected to a tank, and shut off by movement of spools of the plurality of control valves, and an upstream of the hydraulic signal line. A pressure sensor that detects a pressure on the side, and the abnormality determination means includes a plurality of electric lever devices after a predetermined time has elapsed after all operation signals of the plurality of electric lever devices indicate a non-operation state. All of the operation signals indicate a non-operation state, and the operation detecting means detects that any one of the plurality of control valves is operating. It shall be determined to be abnormal.

  As a result, as described in (1) above, the abnormality of the electromagnetic proportional pressure reducing valve or control valve can be detected to stop the hydraulic actuator, and the system configuration can be made simple and inexpensive.

  In addition, the abnormality determination means detects all the operation signals of the plurality of electric lever devices indicating the non-operation state and detects the operation after a predetermined time elapses after all the operation signals of the plurality of electric lever devices indicate the non-operation state. When it is detected by the means that any one of the plurality of control valves is operating, it is determined to be abnormal. For example, even when the hydraulic oil temperature is low, such as when working in a cold region, An erroneous determination due to the influence of the residual pressure of the hydraulic signal line can be prevented, and the reliability of the abnormality determination can be improved. Further, since it is not necessary to increase the passage diameter of the hydraulic signal line in order to reduce the influence of the residual pressure of the hydraulic signal line, there is no need to increase the size of the control valve housing, and the remaining hydraulic signal line can be reduced with an inexpensive configuration. An erroneous determination due to the influence of pressure can be prevented.

  (7) Further, in the above (6), the present invention further includes temperature detection means for detecting the temperature of the hydraulic oil used in the pilot hydraulic power source, and the abnormality determination means determines the predetermined time by the temperature detection means. It is calculated as a variable value depending on the temperature of the detected hydraulic oil, and the abnormality is determined.

  In this way, by calculating the delay time for starting the abnormality determination as a variable value depending on the hydraulic oil temperature at that time, it is possible to prevent erroneous determination when there is no abnormality in the electromagnetic proportional pressure reducing valve and the control valve. When there is an abnormality in the valve and the control valve, the abnormality can be detected more quickly and reliably, and the reliability of the abnormality determination can be improved.

  According to the present invention, when an abnormality occurs in the electromagnetic proportional pressure reducing valve, the hydraulic actuator is stopped, and the work machine member driven by these hydraulic actuators is stopped. Accidents can be prevented and safety is excellent. Moreover, even if any of the plurality of control valves or the electromagnetic proportional pressure reducing valves malfunctions, the operation state can be detected by one sensor (pressure sensor), so that the system configuration is extremely simple and inexpensive.

  Further, according to the present invention, the operation detecting means comprising the hydraulic signal line and the pressure sensor detects the operation state of the control valve itself, so that not only when an abnormality occurs in the electromagnetic proportional pressure reducing valve, but also there is an abnormality in the control valve. If this occurs, it can be detected and the hydraulic actuators can be stopped to prevent unforeseen accidents due to undesired operations of the work implement members driven by these hydraulic actuators. Can be improved.

  Further, according to the present invention, the abnormality determination means is configured such that all the operation signals of the plurality of electric lever devices are not operated after a predetermined time has elapsed after all the operation signals of the plurality of electric lever devices indicate the non-operation state. When the operation detecting means detects that one of the spools of the plurality of control valves is operating, the hydraulic oil temperature is low, for example, when working in a cold region, for example, to determine that there is an abnormality. Even in such a case, it is possible to prevent erroneous determination due to the influence of the residual pressure of the hydraulic signal line, and to improve the reliability of abnormality determination. Further, since it is not necessary to increase the passage diameter of the hydraulic signal line in order to reduce the influence of the residual pressure of the hydraulic signal line, there is no need to increase the size of the control valve housing, and the remaining hydraulic signal line can be reduced with an inexpensive configuration. An erroneous determination due to the influence of pressure can be prevented.

  In addition, according to the present invention, since the delay time for starting the abnormality determination is calculated as a variable value depending on the hydraulic oil temperature at that time, it is possible to prevent erroneous determination when there is no abnormality in the electromagnetic proportional pressure reducing valve and the control valve. When there is an abnormality in the electromagnetic proportional pressure reducing valve and the control valve, the abnormality can be detected more quickly and reliably, and the reliability of the abnormality determination can be improved.

  Embodiments of a hydraulic drive system for a construction machine according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a circuit diagram of a hydraulic drive system according to a first embodiment of the present invention.

  In FIG. 1, a hydraulic drive system includes a prime mover (engine) 1, a variable displacement main hydraulic pump 2 and a fixed displacement pilot pump 3 driven by the prime mover 1, and pressure oil discharged from the main hydraulic pump 2. A plurality of hydraulic actuators including hydraulic cylinders 4 and 5 and a hydraulic motor 6 driven by the motor, and pilot-operated control for controlling the flow (flow rate and direction) of pressure oil supplied to the hydraulic cylinders 4 and 5 and the hydraulic motor 6 Electromagnetic proportional pressure reducing valves 10a, 10b to 12a that control the corresponding control valves by reducing and outputting the pressure of the control oil including the valves 7 to 9 and the pressure oil pressure (pilot pressure) discharged from the pilot pump 3. , 12b and a plurality of electromagnetic proportional pressure reducing valves and a discharge oil passage 3a of the pilot pump 3, and the pressure of the pressure oil discharged from the pilot pump 3 (pi Tsu DOO pressure) defines a pilot relief valve 14 which forms a pilot hydraulic source 13, and a tank 15.

  In addition, the hydraulic drive system includes electric lever devices 20 and 21 that command the operation of the hydraulic cylinder 4 and the hydraulic motor 6, and a gate lock lever (not shown) when the worker gets on or off the vehicle to ensure the safety of the worker. The gate lock lever switch 22 that is activated by operating the pilot pressure source 10 and the pilot lock line that extends from the pilot hydraulic power source 13 to the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b can be communicated and cut off. The switching valve 24 and the hydraulic signal line whose upstream side is connected to the pilot hydraulic pressure source 13 (discharge oil passage 3a of the pilot pump 3) and whose downstream side is connected to the tank line 32, and is shut off by the movement of the spools of the control valves 7-9. 33 and a pressure sensor for detecting the operating state of the control valves 7 to 9 by detecting the pressure upstream of the hydraulic signal line 33 5 and the electric operation signals VL1, VL2; VL3, VL4 of the electric lever devices 20, 21; the instruction signal GL of the gate lock lever switch 22; and the monitoring signal EL of the pressure sensor 25 are input to perform predetermined signal processing. , The drive signals corresponding to the operation signals VL1, VL2; VL3, VL4 are output to the solenoid drive parts of the electromagnetic proportional pressure reducing valves 10a or 10b-12a or 12b, respectively, and the signals VL1, VL2; VL3, VL4, GL, EL A controller (control means) 26 that performs predetermined determination processing based on the electromagnetic switching valve 24 is provided.

  The operation lever 20a of the electric lever device 20 can be rotated in the left-right direction along the paper surface in FIG. 1 and the cross direction perpendicular to the paper surface. For example, the operation lever 20a is rotated in the left-right direction along the paper surface. And the operation signal VL1 is output to drive the hydraulic cylinder 4, and the operation signal VL2 is output to drive the hydraulic motor 6 when the operation lever 20a is rotated in the front and back direction perpendicular to the paper surface. Similarly, the operation lever 21a of the electric lever device 21 can be rotated in the cross direction. When the operation lever 21a is rotated in one direction of the cross, the hydraulic cylinder 5 is driven, and when the operation lever 21a is rotated in the other direction of the cross. Another hydraulic actuator not shown is driven.

  The control valves 7 to 9 are center bypass type valves and have a center bypass passage located on the center bypass line 31. The center bypass passage connects the control valves 7 to 9 in series to the center bypass line 31 and can be communicated and blocked by movement of the spool of the control valves 7 to 9. The upstream side of the center bypass line 31 is connected to the discharge oil passage 2 a of the main hydraulic pump 2, and the downstream side is connected to the tank line 32.

  Further, the control valves 7 to 9 have a signal passage which is located on the hydraulic signal line 33 and connects the control valves 7 to 9 in series. In this signal passage, the spool of the control valves 7 to 9 is in a neutral position. In some cases, the hydraulic signal line 33 is communicated, and when the spools of the control valves 7 to 9 are moved from the neutral position, the hydraulic signal line 33 is shut off. A fixed throttle 34 is provided between the discharge oil passage 3 a of the hydraulic signal line 33 and the control valve 7 on the most upstream side of the center bypass line, and the pressure sensor 25 is provided between the fixed throttle 34 and the control valve 7. Yes. The fixed throttle 34 is for reducing the flow rate of the oil discharged from the pilot pump 3 in the hydraulic signal line 33.

  The electromagnetic switching valve 24 is for a gate lock lever (actuated in response to the operation of the gate lock lever switch 22). In the present embodiment, the electromagnetic switching valve 24 is also used as a switching valve when an abnormality is detected. This is also used (described later).

  The hydraulic signal line 33 and the pressure sensor 25 constitute an operation detection unit that detects whether any of the spools of the plurality of control valves 7 to 9 is in an operating state.

  FIG. 2 is a view showing an appearance of a hydraulic excavator on which the hydraulic drive system is mounted. The hydraulic excavator includes a lower traveling body 100, an upper swing body 101, and a front work machine 102. The lower traveling body 100 has left and right crawler traveling devices 103a and 103b, and is driven by left and right traveling motors 104a and 104b. A blade 105 is provided at the front of the lower traveling body and is moved up and down by a blade cylinder 106. The upper turning body 101 is driven to turn about the axis O on the lower traveling body 100 by a turning motor (not shown). The front work machine 102 is provided at the front part of the upper swing body 101 so as to be lifted and lowered. The front work machine 102 has an articulated structure having a boom 110, an arm 111, and a bucket 112. The boom 110, the arm 111, and the bucket 112 are in a plane including the axis O in the boom cylinder 113, the arm cylinder 114, and the bucket cylinder 115, respectively. Driven by rotation.

  In FIG. 1, hydraulic cylinders 4 and 5 are, for example, a boom cylinder 113 and an arm cylinder, respectively, and the hydraulic motor 6 is, for example, a turning motor. The hydraulic drive system is also provided with other hydraulic actuators such as the bucket cylinder 115 and traveling motors 104a and 104b and their control valves, but they are omitted in FIG.

  FIG. 3 shows operation amounts (lever operation amounts) of the operation levers 20a and 21a of the electric lever devices 20 and 21 and operation signals (control voltages) VL1 and VL2; VL3 and VL4 (represented by VL) as output signals thereof. It is a figure which shows the relationship and the relationship between the operation signal VL and the target pilot pressure calculated by the controller 26. The lever operation amount corresponds to one side of each of the operation levers 20a, 21a in the left-right direction and the up-down direction (that is, one of the left direction, the right direction, the up direction, and the down direction).

  For example, when the operating lever 20a is operated in the left direction in the figure, the electric lever device 20 outputs a control voltage (V) proportional thereto as the operation signal VL1. The controller 26 receives the operation signal VL1, and calculates a target pilot pressure Pi proportional to the operation signal VL1. This target pilot pressure Pi is converted into an electric drive signal in the controller 26 and output to, for example, the electromagnetic proportional pressure reducing valve 10a. The solenoid drive portion of the electromagnetic proportional pressure reducing valve 10a is excited by the drive signal, and the electromagnetic proportional pressure reducing valve 10a outputs a pilot pressure corresponding to the target pilot pressure Pi. The control valve 7 is driven to the right in the figure by this pilot pressure, the discharge oil of the main hydraulic pump 2 is supplied to the bottom side of the hydraulic cylinder 4, and the hydraulic cylinder 4 is driven in the extending direction.

  The same applies when the operation lever 20a is operated in the right direction in the figure. The electrical drive signal generated by the controller 26 is output to the electromagnetic proportional pressure reducing valve 10b, and the electromagnetic proportional pressure reducing valve 10b is the target calculated by the controller 26. A pilot pressure corresponding to the pilot pressure Pi is output. The control valve 7 is driven in the left direction in the figure by this pilot pressure, the discharge oil of the main hydraulic pump 2 is supplied to the rod side of the hydraulic cylinder 4, and the hydraulic cylinder 4 is driven in the contracting direction.

  The same applies when the operation lever 20a is operated upward or downward, and when the operation lever 21a of the operation lever device 21 is operated leftward, rightward, upward or downward.

  FIG. 4 is a diagram illustrating the relationship between the operation amount of the control valves 7 to 9 and the monitoring signal EL of the pressure sensor 25. When all of the control valves 7 to 9 are in the neutral position, the pressure of the hydraulic signal line 33 is the tank pressure (approximately 0), and the pressure sensor 25 outputs 0 V (OFF signal) as the monitoring signal EL. When any one of the control valves 7 to 9 is operated to move from the neutral position, a predetermined pressure is generated in a portion of the hydraulic signal line 33 between the fixed throttle 34 and the moved control valve, and the pressure sensor 25 is The pressure is detected, and the maximum voltage Vmax (ON signal) is output as the monitoring signal EL. The monitoring signal EL of the pressure sensor 25 is input to the controller 26. The controller 26 operates when the operation signals VL1, VL2; VL3, VL4 output from the electric lever devices 20, 21 are all 0, that is, when both the operation levers 20a, 21a are neutral (both the electric lever devices 20, 21). When the control signal EL of the pressure sensor 61 is not operated, it has a determination function for determining what state the monitoring signal EL of the pressure sensor 61 is, that is, whether it is an abnormal state or a normal state.

  FIG. 5 is a flowchart showing the processing contents of the controller 26.

  The controller 26 first operates the operation signals VL1, VL2; VL3, VL4 (represented by VL as appropriate) from the electric lever devices 20, 21, and the gate lock instruction signal (hereinafter simply referred to as instruction signal) GL from the gate lock lever switch 22. Is read (procedure S1). Next, it is determined whether or not the read instruction signal GL is ON (step S2). If the instruction signal GL is ON, the gate lock signal RL output to the electromagnetic switching valve 24 is turned ON and output (step S3). If the instruction signal GL is OFF, the gate lock signal RL output to the electromagnetic switching valve 24 is turned OFF and output (step S4).

  When the ON gate lock signal RL is output to the electromagnetic switching valve 24 in step S3, the controller 26 calculates the control pressure Pi corresponding to the read operation signal VL (step S5). The control pressure Pi is a target value of the control pilot pressure output from the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b. This calculation is performed based on the functional relationship between the operation signal VL and the control pressure Pi as shown in FIG. 3 stored in advance in the memory of the controller 26. This control pressure Pi is converted into drive signals for the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b, and is output from the controller 26 to the corresponding drive portions of the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b (step S5). ).

  If an OFF gate lock signal RL is output to the electromagnetic switching valve 24 in step 4, the process returns to step S1, and steps S1, S3, and S4 are performed until the instruction signal GL is turned ON and the gate lock signal RL is turned ON. repeat.

  Next, the controller 26 reads the monitoring signal EL that is an output signal of the pressure sensor 25 (step S6), and when the operation signal (control voltage) VL of the electric lever device 20, 21 is 0 V, that is, which of the operation levers 20a, 21a If the operation signals VL1, VL2; VL3, VL4 are all 0V, it is determined whether the monitoring signal EL is a 0V signal (OFF signal) corresponding to the tank pressure (step S7). That is, processing is performed to determine whether the state is abnormal or normal based on the operation signals VL1, VL2; VL3, VL4 and the monitoring signal EL.

  When the control valves 7-9 and the electromagnetic proportional pressure reducing valves 10a, 10b-12a, 12b are functioning normally, the determination result of this step S7 is yes, and the machine (hydraulic excavator) operates normally. On the other hand, when any of the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b fails or any of the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b is malfunctioning due to contamination. In step S7, although the operation signal VL corresponding to the electromagnetic proportional pressure reducing valve is 0V, the monitoring signal EL becomes a value other than 0V, and the determination result in step 7 is NO. That is, the operation signal VL and the monitoring signal EL are determined to be abnormal.

  If it is determined in step 7 that the operation signal VL and the monitoring signal EL are in an abnormal state, the controller 26 switches the gate lock signal RL from ON to OFF and outputs it to the electromagnetic switching valve 24 (step 8). Thereby, the electromagnetic switching valve 24 is switched to the position shown in the figure, the communication of the pilot line 23 is cut off, and the supply of pressure oil from the pilot pump 3 to the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b is cut off. . As a result, even if any of the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b fails or malfunctions, the control valve that has been operated so far is returned to the neutral position, and the hydraulic cylinders 4, 5 and hydraulic pressure The operation of all hydraulic actuators including the motor 6 is stopped. Along with this, all work implement members such as the boom 111, the arm 115, and the revolving structure 101 are stopped.

  In the above, the functions of the procedures S6 and S7 are abnormal based on the operation signals VL1 and VL2; VL3 and VL4 of the plurality of electric lever devices 20 and 21 and the detection results of the operation detection means (the hydraulic signal line 33 and the pressure sensor 25). The function of step S8 constitutes an actuator stopping means for stopping the plurality of hydraulic actuators 4, 5, 6 when the abnormality determining means determines that there is an abnormality.

  Next, the operation of the present embodiment configured as described above will be described.

  When the operator lowers the gate lock lever with the intention of starting work when boarding, the gate lock lever switch 22 shown in FIG. 1 is turned on, and a gate lock instruction signal GL is output to the controller 26. Thereafter, when the operator rotates one of the electric lever devices 20 and 21 shown in FIG. 1, for example, the operation lever 20 a of the electric lever device 20, for example, to the left in the drawing, the operation signal VL <b> 1 is output to the controller 26. The The controller 26 reads the operation signal VL1 and the instruction signal GL (procedure S1), determines whether or not the read gate lock instruction signal GL is ON (procedure S2). In this case, since the instruction signal GL is ON, An ON gate lock signal RL is output to the electromagnetic switching valve 24. As a result, the electromagnetic switching valve 24 is switched from the position shown in the figure, and the pilot pipe line 23 is communicated, so that the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b are in a state capable of generating the control pilot pressure.

  Next, the controller 26 calculates a control pressure Pi corresponding to the read operation signal VL1, converts this control pressure Pi into a drive signal for the electromagnetic proportional pressure reducing valve 10a, and sends the drive signal to the drive portion of the electromagnetic proportional pressure reducing valve 10a. Is output (step S5). The electromagnetic proportional pressure reducing valve 20a is actuated by the drive signal, and the pilot pressure given from the pilot pump 3 is reduced by the electromagnetic proportional pressure reducing valve 20a and output as a control pilot pressure. The control pilot pressure output from the electromagnetic proportional pressure reducing valve 20a is applied to the drive unit on the left side of the control valve 7 in the figure, and the control valve 7 is switched to the position on the left side in the figure. Accordingly, the pressure oil discharged from the main hydraulic pump 2 driven by the engine 1 is supplied to the bottom side of the hydraulic cylinder 4 through the control valve 7, and the hydraulic cylinder 4 expands. Thereby, the raising operation of the boom 111 is performed.

  When the control valve 7 is switched to the left position in the drawing, the hydraulic signal line 33 is shut off by the control valve 7 and a predetermined pressure is generated at a portion of the hydraulic signal line 33 between the fixed throttle 34 and the control valve 7. To do. The pressure sensor 25 detects the pressure and outputs the maximum voltage Vmax (ON signal) as the monitoring signal EL as shown in FIG.

  The controller 26 reads the monitoring signal EL (procedure S6), and determines whether it is abnormal or normal based on the operation signal VL and the monitoring signal EL (procedure S7). In this case, since the operation signal VL1 is not 0V and the monitoring signal EL is ON (not 0V), it is determined that the operation is normal and the machine (hydraulic excavator) continues to operate normally.

  Thereafter, the operation lever 20a of the electric lever device 20 is returned to the neutral position, and when the operation signal VL1 becomes 0V, the controller 26 calculates the control pressure Pi = 0 and outputs a drive signal to be output to the drive unit of the electromagnetic proportional pressure reducing valve 10a. The voltage is set to 0 V (procedure S5). When the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b are functioning normally, the control pilot output from the electromagnetic proportional pressure reducing valve 10a when the drive signal output to the drive unit of the electromagnetic proportional pressure reducing valve 10a becomes 0V. The pressure also becomes 0 (tank pressure), and the control valve 7 returns to the neutral position. As a result, the control valve 7 portion of the hydraulic signal line 33 is in communication, the pressure of the downstream portion of the fixed throttle 34 of the hydraulic signal line 33 becomes 0 (tank pressure), and the pressure sensor 25 detects the pressure, and FIG. As shown, 0V (OFF signal) is output as the monitoring signal EL. Therefore, the determination result of step S7 performed by the controller 26 at this time is yes, and the controller 26 does nothing.

  On the other hand, in the event that the electromagnetic proportional pressure reducing valve 10a breaks down or malfunctions due to contamination, the electromagnetic proportional pressure reducing valve 10a does not increase the control pilot pressure even if the operating lever 20a is returned to the neutral position. The control signal 7 continues to be output and the control valve 7 does not return to the neutral position, the monitoring signal EL output from the pressure sensor 25 remains at the maximum voltage Vmax (ON signal), and the determination result of step 7 is NO. For this reason, the controller 26 outputs an OFF gate lock signal RL to the electromagnetic switching valve 24 (procedure 8), whereby the electromagnetic switching valve 24 is switched to the position shown in FIG. The supply of pressure oil from the pump 3 to the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b is shut off. As a result, the control valve 7 which has been operated so far is returned to the neutral position, and the operation of all the hydraulic actuators including the hydraulic cylinders 4 and 5 and the hydraulic motor 6 is stopped. Along with this, all work implement members such as the boom 111, the arm 115, and the revolving structure 101 are stopped.

  When the operation lever 20a of the electric lever device 20 is operated in the right direction in the figure, or when the operation lever 20a of the electric lever device 20 is operated in the front and back direction of the paper, the operation lever 21a of the electric lever device 21 is shown in the horizontal direction or the front and back direction of the paper. The same applies to the operation.

  Thus, according to the present embodiment, when an abnormality occurs in the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b, the operation of all the hydraulic actuators including the hydraulic cylinders 4, 5 and the hydraulic motor 6 is stopped. Since the work implement member driven by these hydraulic actuators is stopped, an unexpected accident due to an undesired operation of the work implement member can be prevented in advance, and excellent safety is achieved.

  In addition, a hydraulic signal line 33 that is blocked by the movement of the spool of the control valves 7 to 9 and a pressure sensor 25 that detects the pressure on the upstream side of the hydraulic signal line 33 are provided, and any one of the control valves 7 to 9 is provided. Since it is detected whether or not the spool is in an operating state, even if any of the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b malfunctions, the operating state should be detected by one sensor (pressure sensor). The system configuration is extremely simple and inexpensive.

  Furthermore, according to the present embodiment, when an abnormality occurs in the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b regardless of the instruction state of the gate lock lever switch 22, the electromagnetic switching valve 24 for the gate lock lever is used. Can be controlled to shut off the pilot line 23 and stop the hydraulic actuator. At that time, since the electromagnetic switching valve 24 for the gate lock lever is also used as a switching valve at the time of detecting an abnormality, the system configuration is further simplified and inexpensive.

  A second embodiment of the present invention will be described with reference to FIGS. In FIG. 6, the same components as those shown in FIG. In this embodiment, the prime mover is stopped when the electromagnetic proportional pressure reducing valve is abnormal.

  In FIG. 6, a throttle dial 41 and an engine controller 42 are provided as control means of the prime mover 1, and the prime mover 1 is provided with an electronic governor 43. The throttle dial 41 is operated by an operator to set a target rotational speed of the prime mover 1, and the operation signal is input to the engine controller 42. Further, an engine stop signal ES is input from the controller 26A to the engine controller 42. The engine controller 42 performs predetermined calculation processing based on the setting signal from the throttle dial 41 and the engine stop signal ES, and outputs a target rotational speed signal to the electronic governor 43. The electronic governor 43 controls the fuel injection amount based on the target rotational speed signal so that the rotational speed of the prime mover 1 becomes the target rotational speed.

  FIG. 7 is a flowchart showing the processing contents of the controller 26A. The difference from the processing contents of the first embodiment shown in FIG. 5 is that if it is determined in step 7 that the operation signal VL and the monitoring signal EL are in an abnormal state, the engine stop signal ES is set in step 8A. It is to generate and stop the prime mover 1.

  FIG. 8 is a functional block diagram showing the processing contents of the engine controller 42. The engine controller 42 has functions of a target rotation speed setting unit 42a, an engine stop rotation speed setting unit 42b, an engine stop determination unit 42c, and a target rotation speed switching unit 42d.

  The target rotational speed setting unit 42a receives a setting signal from the throttle dial 41, and sets the target rotational speed of the prime mover 1 corresponding to this setting signal. The rotation speed set by the target rotation speed setting unit 42a includes an idle rotation speed, a maximum rotation speed, and an intermediate rotation speed. The intermediate rotation speed is variably changed from the idle rotation speed to the maximum rotation speed. Increase.

  The engine stop rotation speed setting unit 42b stores 0 rotation speed as a target rotation speed for stopping the prime mover 1.

  The engine stop determination unit 42c receives an engine stop signal ES from the controller 26A, determines whether or not the engine needs to be stopped, and switches the target rotational speed switching unit 42d from the illustrated position when it is determined that the engine needs to be stopped. When the engine stop signal ES is not input, an OFF determination signal is output, and when the engine stop signal ES is input, an ON determination signal is output.

  When the determination signal of the engine stop determination unit 42c is OFF, the target rotation number switching unit 42d is at the position shown in the figure, selects the target rotation number set by the target rotation number setting unit 42a, and determines by the engine stop determination unit 42c. When the signal is turned ON, the position is switched from the position shown in the figure, and the zero speed set in the engine stop speed setting section 42b is selected.

  The target rotational speed selected by the target rotational speed switching unit 42d is output to the electronic governor 43 as a target rotational speed signal.

  In the above, the functions of steps S6 and S7 in FIG. 7 are similar to the first embodiment in that the operation signals VL1 and VL2; VL3 and VL4 of the plurality of electric lever devices 20 and 21 and the motion detection means (hydraulic signal line) 33 and an abnormality determination means for determining abnormality based on the detection results of the pressure sensor 25), the function of step S8A, the engine stop rotation speed setting unit 42b of FIG. 8, the engine stop determination unit 42c, and the target rotation speed Each function of the switching unit 42d constitutes an actuator stopping unit that stops a plurality of hydraulic actuators 4, 5, and 6 when the abnormality determining unit determines that there is an abnormality.

  Therefore, when it is determined in step 7 of FIG. 7 that the engine is in the normal state, the engine stop signal ES is not output from the controller 26A, and the target rotational speed signal corresponding to the setting signal of the throttle dial 41 is electronically transmitted from the engine controller 42. It is output to the governor 43 and controlled so that the rotational speed of the prime mover 1 becomes the target rotational speed. As a result, the machine (hydraulic excavator) can be operated as before.

  On the other hand, when the operation signal VL and the monitoring signal EL are determined to be abnormal in step 7 of FIG. 7, the engine stop signal ES is output from the controller 26A (step 8A), and the engine controller 42 sends the electronic governor 43. A target rotational speed of 0 rotational speed is output, and the prime mover 1 stops. As a result, the discharge flow rate of the main hydraulic pump 2 becomes zero, and the operation of all hydraulic actuators including the hydraulic cylinders 4 and 5 and the hydraulic motor 6 is stopped. Along with this, all work implement members such as the boom 111, the arm 115, and the revolving structure 101 are stopped.

  As described above, the present embodiment can provide the same effects as those of the first embodiment.

  Further, according to the present embodiment, the operation detecting means comprising the hydraulic signal line 33 and the pressure sensor 25 detects the operating state of the control valves 7 to 9 itself, so that the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b. Not only when an abnormality occurs in the control valve, but also when an abnormality occurs in the control valves 7 to 9, this is detected and the hydraulic actuator is stopped, and the undesired operation of the work implement member driven by these hydraulic actuators In order to prevent unforeseen accidents due to accidents, safety can be further improved.

  A third embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a flowchart showing the processing contents of the controller in the present embodiment. In the figure, the same reference numerals are given to procedures for performing the same processing as the flowchart shown in FIG. This embodiment prevents erroneous determination due to the influence of the residual pressure of the hydraulic signal line. In this embodiment, the configuration of the hydraulic drive system is the same as that in the first embodiment shown in FIG. 1, for example, and in the following description, refer to FIG. 1 as appropriate for the configuration of the hydraulic drive system. To do.

  In FIG. 9, the processing from step S1 to step S6 is the same as the processing of the flowchart in the first embodiment shown in FIG. After reading the monitoring signal EL that is the output signal of the pressure sensor 25 in step S6, the controller 26 determines whether the operation signal (control voltage) VL of the electric lever devices 20, 21 is 0 V, that is, which of the operation levers 20a, 21a It is also determined whether the operation signals VL1 and VL2; VL3 and VL4 all indicate 0 V (step S11).

  If it is determined in step S11 that one of the operation levers 20a and 21a is not neutral, the timer count is cleared to 0 (step S13), the process returns to step S1, and the above procedure is repeated. When it is determined that both of the operation levers 20a and 21a are neutral, the timer is counted up and the elapsed time after the neutralization of the operation lever is counted (step S12). Next, it is determined whether or not the elapsed time counted by the timer has exceeded a preset delay time of T seconds (eg, 1.5 seconds) (step S14), and it is determined that T seconds or more have not elapsed. Then, the procedure returns to step S1, and the processing from step S1 to step S12 is repeated until the elapsed time counted by the timer has elapsed for T seconds or more. If it is determined in step S14 that the elapsed time counted by the timer has elapsed for T seconds or more, the process proceeds to abnormality determination processing (step S15). The contents of the abnormality determination process are the same as the processes of steps S7 and S8 shown in FIG. 5 in the first embodiment, for example. The abnormality determination process may be the process of steps S7 and S8 shown in FIG. 7 in the second embodiment.

  Next, the effect of this Embodiment comprised as mentioned above is demonstrated using FIG. FIG. 10 is a diagram showing the concept of prevention of erroneous determination in the present embodiment. FIG. 10A shows the operation levers of the electric lever devices 20 and 21 when there is no abnormality in the electromagnetic proportional pressure reducing valve and the control valve. The pressure of the hydraulic signal line 33 detected by the pressure sensor 25 when the operation signal becomes 0V and the drive signal to the electromagnetic proportional pressure reducing valves 10b, 11b, 12b becomes 0 is returned to neutral from the operation state. FIG. 10B shows an actual change in the pressure of the hydraulic signal line 33, and FIG. 10C shows the operating principle of the present invention.

  In FIG. 10A, the operation levers 20a and 21a of the electric lever devices 20 and 21 are returned to the neutral state from the operation state, the operation signal becomes 0V, and the drive signal to the electromagnetic proportional pressure reducing valves 10b, 11b and 12b is 0. When there is no abnormality in the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b and the control valves 7 to 9, the control pilot pressure output from the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b is 0 (tank pressure). Since all the control valves 7 to 9 return to the neutral position, the hydraulic signal line 33 is in a communicating state. At this time, ideally, the hydraulic signal line detected by the pressure sensor 25 at the same time as the operation signal becomes 0V. The pressure 33 is also almost 0 (tank pressure). In this case, even if the determination of abnormality is started at the same time as the operation signal becomes 0 V, it is not determined as abnormal and normal operation is possible. However, the control valves 7 to 9 are configured as spool valves arranged in one control valve, and the hydraulic signal line 33 is formed as an internal passage in the block (housing) of the control valve. When the operating oil temperature is low, such as when working in a cold region, the residual pressure is affected by the viscosity of the operating oil. Therefore, actually, even if the control valves 7 to 9 return to the neutral position and the hydraulic signal line 33 is in the communication state, the pressure of the hydraulic signal line 33 does not immediately become zero, and FIG. As shown, the pressure in the hydraulic signal line 33 becomes zero with a certain time delay. For this reason, if the determination of abnormality is started at the same time as the operation signal becomes 0 V, there is a possibility that it is erroneously determined that the abnormality is related to normality.

  In order to reduce the influence of the residual pressure and prevent erroneous determination, it is conceivable to increase the passage diameter of the hydraulic signal line 33. However, in order to increase the passage diameter of the hydraulic signal line 33, it is necessary to enlarge the housing of the control valve, which increases the cost.

  Therefore, in the present invention, as shown in FIG. 10C, the determination of abnormality is not started at the same time as the operation signal becomes 0V, but after the operation signal becomes 0V in consideration of the influence of the residual pressure, Abnormality determination is started after a predetermined delay time has elapsed. Thereby, even if there is a residual pressure in the hydraulic signal line 33, it is possible to make an accurate determination without being erroneously determined as abnormal.

  The present embodiment is based on such an idea. When it is determined that both the operation levers 20a and 20b are neutral as described above, the timer is counted up (step S12), and the elapsed time is counted. After elapse of a predetermined delay time or more, the process proceeds to an abnormality determination process (step S14). Thus, when an abnormality occurs in the electromagnetic proportional pressure reducing valves 10a, 10b to 12a, 12b, the abnormality is detected in the same manner as in the first embodiment or the second embodiment, and the hydraulic cylinders 4, 5 and the hydraulic motor 6 are detected. All hydraulic actuators including the engine can be stopped to ensure safety, and when there are no abnormalities in the electromagnetic proportional pressure reducing valve and control valve, the hydraulic oil temperature is low, such as when working in cold regions. However, since the abnormality determination is started after a predetermined time has elapsed after the operation signal becomes 0 V, erroneous determination due to the influence of the residual pressure in the hydraulic signal line 33 can be prevented.

  As described above, according to the present embodiment, the same effects as those of the first and second embodiments can be obtained, and even when the hydraulic oil temperature is low, such as when working in a cold region, the hydraulic pressure An erroneous determination due to the influence of the residual pressure of the signal line 33 can be prevented, and the reliability of the abnormality determination can be improved. Moreover, since it is not necessary to enlarge the housing of the control valve, it is possible to prevent erroneous determination due to the influence of the residual pressure of the hydraulic signal line 33 with an inexpensive configuration.

  A fourth embodiment of the present invention will be described with reference to FIGS.

  FIG. 11 is a circuit diagram of a hydraulic drive system for a construction machine according to the fourth embodiment of the present invention. In FIG. 11, the same components as those shown in FIG. In the present embodiment, the delay time for starting the abnormality determination is a variable value that depends on the hydraulic oil temperature.

  In FIG. 11, a temperature sensor 44 for detecting the temperature of hydraulic oil used in the hydraulic pumps 2 and 3 is provided, and a detection signal of the temperature sensor 44 is input to the controller 26B. The controller 26B calculates a determination start delay time based on the detection signal of the temperature sensor 44, and performs abnormality determination after the delay time elapses. Other configurations are the same as those of the first embodiment shown in FIG.

  FIG. 12 is a flowchart showing the processing contents of the controller 26B in the present embodiment. In the figure, the same steps as those in the flowchart shown in FIG.

  In FIG. 12, the controller 26B reads the monitoring signal EL that is the output signal of the pressure sensor 25 in step S6, and then reads the hydraulic oil temperature Ts (° C.) that is the detection signal of the temperature sensor 44 (step S21). The delay time T is calculated using a function relationship set in advance based on the hydraulic oil temperature Ts (step S22).

  FIG. 13 is a diagram showing a functional relationship between the delay time T and the hydraulic oil temperature Ts used in step S22, and the relationship between the two is set so that the delay time T increases as the hydraulic oil temperature Ts decreases.

  Returning to FIG. 12, after calculating the delay time T in this way, the process proceeds to step S11, and if it is determined that both the operation levers 20a and 21a are neutral, the timer is counted up (step S12). After the time elapses over the delay time T calculated in step S22, the process proceeds to the abnormality determination process (step S14).

  When the delay time T at the start of abnormality determination is set as a constant value as in the third embodiment, the delay time T is set longer assuming the most severe conditions (when the hydraulic oil temperature is the lowest). There is a need. However, at a high temperature at which the influence of the residual pressure in the hydraulic signal line 33 is small, the delay time T becomes a dead time for the abnormality determination process. In the present embodiment, the hydraulic oil temperature is detected, and the abnormality determination start delay time T is calculated as a variable value depending on the hydraulic oil temperature. As a result, when the working oil temperature is low, such as when working in a cold region, the delay time T is calculated to be long, and erroneous determination when there is no abnormality in the electromagnetic proportional pressure reducing valve and the control valve is reliably prevented. On the other hand, when the hydraulic oil temperature is high, such as when working in a warm area or after a sufficiently warm-up operation, the delay time T is calculated to be short, so when the operating lever returns to the neutral position, When the process proceeds to the abnormality determination process and the electromagnetic proportional pressure reducing valve and the control valve are abnormal, the abnormality can be detected more quickly and reliably.

  Thus, according to the present embodiment, the same effect as the third embodiment is obtained, and the delay time T for starting the abnormality determination is calculated as a variable value depending on the hydraulic oil temperature at that time. When there is an abnormality in the electromagnetic proportional pressure reducing valve and the control valve, it is possible to detect the abnormality more quickly and reliably, while preventing an erroneous determination when there is no abnormality in the electromagnetic proportional pressure reducing valve and the control valve. Can be improved.

  In the present embodiment, the temperature of the hydraulic oil is detected by the temperature sensor 44, and the abnormality determination start delay time T is obtained as a variable value depending on the hydraulic oil temperature. However, the engine 1 or a radiator (not shown) A temperature sensor for detecting the cooling water temperature may be provided, the cooling water temperature of the engine 1 may be detected by this temperature sensor, and the abnormality determination start delay time T may be obtained as a variable value depending on the cooling water temperature. Since the hydraulic oil temperature and the cooling water temperature have a correlation, even if the abnormality determination is performed by obtaining the abnormality determination start delay time as a variable value depending on the cooling water temperature, the same effect can be obtained.

1 is a circuit diagram of a hydraulic drive system for a construction machine according to a first embodiment of the present invention. It is a figure which shows the external appearance of the hydraulic excavator by which a hydraulic drive system is mounted. It is a figure which shows the relationship between the operation amount (lever operation amount) of the operation lever of an electric lever apparatus, and the operation signal which is the output signal, and the relationship between the operation signal and the target pilot pressure calculated by a controller. It is a figure which shows the relationship between the operation amount of a control valve, and the output signal of a pressure sensor. It is a flowchart which shows the processing content of the controller in the 1st Embodiment of this invention. It is a circuit diagram of the hydraulic drive system of the construction machine concerning the 2nd Embodiment of this invention. It is a flowchart which shows the processing content of the controller in the 2nd Embodiment of this invention. It is a functional block diagram which shows the processing content of an engine controller. It is a flowchart which shows the processing content of the controller in the 3rd Embodiment of this invention. When there is no abnormality in the electromagnetic proportional pressure reducing valve and control valve, the operating lever of the electric lever device is returned from the operating state to neutral, the operation signal becomes 0V, and the pressure sensor when the drive signal to the electromagnetic proportional pressure reducing valve becomes 0 It is explanatory drawing which shows together the change of the pressure of the hydraulic signal line which detects, and the change of the operation signal of an electric lever apparatus. It is a circuit diagram of the hydraulic drive system of the construction machine concerning the 4th Embodiment of this invention. It is a flowchart which shows the processing content of the controller in the 4th Embodiment of this invention. It is a figure which shows the relationship between hydraulic oil temperature and delay time.

Explanation of symbols

1 Main hydraulic pump 2 Pilot pump 3 Motor (engine)
4,5 Hydraulic cylinder 6 Hydraulic motor 7-9 Control valve 10a, 10b-12a, 12b Electromagnetic proportional pressure reducing valve 13 Pilot hydraulic power source 14 Pilot relief valve 15 Tank 21 Electric lever device 22 Gate lock lever switch 25 Pressure sensor 26 Controller (control) means)
31 Center bypass line 32 Tank line 33 EL signal line 34 Fixed throttle 41 Throttle dial 42 Engine controller 43 Electronic governor 44 Temperature sensor

Claims (7)

A prime mover, a hydraulic pump driven by the prime mover, a plurality of hydraulic actuators that drive a driven body, and a plurality of hydraulic pilot type that respectively control the flow of pressure oil from the hydraulic pump to the plurality of hydraulic actuators A control valve, a plurality of electromagnetic proportional pressure reducing valves that generate pilot pressures to the plurality of control valves based on a pilot pressure of a pilot hydraulic power source, and a plurality of electric lever devices that command the operations of the plurality of hydraulic actuators. A hydraulic drive system for a construction machine that controls a corresponding one of the plurality of electromagnetic proportional pressure reducing valves according to each operation signal of the plurality of electric lever devices,
Operation detecting means for detecting whether one of the plurality of control valves is in an operating state;
An abnormality determining means for determining an abnormality based on an operation signal of the plurality of electric lever devices and a detection result of the motion detecting means;
Actuator stopping means for stopping the plurality of hydraulic actuators when the abnormality determining means determines that there is an abnormality,
The operation detecting means includes a hydraulic signal line connected upstream to the pilot hydraulic pressure source, connected downstream to the tank, and blocked by movement of spools of the plurality of control valves, and a pressure upstream of the hydraulic signal line. A hydraulic drive system for a construction machine, comprising a pressure sensor for detecting the pressure. The hydraulic drive system for a construction machine according to claim 1,
The abnormality determination means detects that all the operation signals of the plurality of electric lever devices indicate a non-operation state, and the operation detection means detects that any one of the spools of the plurality of control valves is operating. A hydraulic drive system for a construction machine, characterized in that an abnormal condition is determined. The hydraulic drive system for a construction machine according to claim 1,
The actuator stopping means controls the switching valve when the switching valve capable of communicating / blocking a pilot pipe line from the pilot hydraulic power source to the plurality of electromagnetic proportional pressure reducing valves and the abnormality determining means are abnormal. And a hydraulic drive system for construction machinery, characterized in that it has means for blocking the pilot pipeline. The hydraulic drive system for a construction machine according to claim 1,
The hydraulic drive system for a construction machine, wherein the actuator stopping means is means for stopping the prime mover when the abnormality determining means determines that there is an abnormality. The hydraulic drive system for a construction machine according to claim 1,
A switching valve capable of communicating / blocking a pilot line from the pilot hydraulic power source to the plurality of electromagnetic proportional pressure reducing valves;
An instruction means for instructing switching of the switching valve;
The actuator stopping means controls the switching valve when the abnormality determining means determines that there is an abnormality even when the instruction means instructs the switching of the switching valve so that the pilot pipeline communicates. A hydraulic drive system for a construction machine, characterized in that it is means for blocking the pilot pipeline. A prime mover, a hydraulic pump driven by the prime mover, a plurality of hydraulic actuators that drive a driven body, and a plurality of hydraulic pilot type that respectively control the flow of pressure oil from the hydraulic pump to the plurality of hydraulic actuators A control valve, a plurality of electromagnetic proportional pressure reducing valves that generate pilot pressures to the plurality of control valves based on a pilot pressure of a pilot hydraulic power source, and a plurality of electric lever devices that command the operations of the plurality of hydraulic actuators. A hydraulic drive system for a construction machine that controls a corresponding one of the plurality of electromagnetic proportional pressure reducing valves according to each operation signal of the plurality of electric lever devices,
Operation detecting means for detecting whether one of the plurality of control valves is in an operating state;
An abnormality determining means for determining an abnormality based on an operation signal of the plurality of electric lever devices and a detection result of the motion detecting means;
Actuator stopping means for stopping the plurality of hydraulic actuators when the abnormality determining means determines that there is an abnormality,
The operation detecting means includes a hydraulic signal line connected upstream to the pilot hydraulic pressure source, connected downstream to the tank, and blocked by movement of spools of the plurality of control valves, and a pressure upstream of the hydraulic signal line. And a pressure sensor for detecting
The abnormality determining means indicates that after a predetermined time has elapsed after all the operation signals of the plurality of electric lever devices indicate a non-operation state, all the operation signals of the plurality of electric lever devices indicate a non-operation state, and A hydraulic drive system for a construction machine, characterized in that when the operation detecting means detects that any one of the plurality of control valves is operating, an abnormality is determined. The hydraulic drive system for a construction machine according to claim 6,
Temperature detecting means for detecting the temperature of hydraulic oil used in the pilot hydraulic power source,
The hydraulic drive system for a construction machine, wherein the abnormality determination unit calculates the abnormality by calculating the predetermined time as a variable value depending on the temperature of the hydraulic oil detected by the temperature detection unit.

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