JP4271685B2 - Work vehicle and engine restart control method for work vehicle - Google Patents

Description

  The present invention relates to a work vehicle having an idling stop function and an engine restart function, and an engine restart control method in such a work vehicle.

  Recently, in order to save energy and protect the environment, it is required to install an idling stop control function in a work vehicle such as a work vehicle. The idling stop control function is a function that automatically stops the engine when an idle state of the work vehicle occurs, that is, a state where the work vehicle waits while the engine is operating. For example, Patent Documents 1 and 2 disclose work vehicles having an idling stop function.

JP 2003-65097 A JP 2000-96627 A

  In the work vehicle disclosed in Patent Document 1, the idling operation of the engine is automatically stopped when the operation lever is not operated for a set time or when the switch attached to the operation lever is turned ON. The When the operating lever is operated after this automatic engine stop, the engine is automatically started.

  The construction machine disclosed in Patent Document 2 includes a lock position for prohibiting the operation of the hydraulic circuit and an unlocking operation for permitting the operation of the hydraulic circuit in addition to an operation lever for operating the construction machine by instructing the hydraulic circuit. A lock lever for switching between positions is provided. When a predetermined time has elapsed since the lock lever was switched to the lock position, the engine operation is automatically stopped. When the lock lever is switched to the unlock position after the automatic engine stop, the hydraulic circuit is ready for operation and the engine is automatically started.

  However, the work vehicle disclosed in Patent Document 1 has a problem in that when the engine is automatically restarted by the operation of the operation lever, the work vehicle may unexpectedly move in response to the operation lever. In the construction machine disclosed in Patent Document 2, when the operator performs the unlocking operation of the lock lever while operating the operation lever, the hydraulic circuit starts to operate simultaneously when the engine is restarted by the unlocking operation. There is a problem that the construction machine may be moved unexpectedly in response to the operation lever.

  Accordingly, an object of the present invention is to prevent the work vehicle from starting unexpectedly when the engine is restarted after the engine is automatically stopped by the idling stop control in the work vehicle having the idling stop control function.

  A work vehicle according to the present invention includes an engine, a hydraulic circuit driven by the engine, a hydraulic operation unit driven by the hydraulic circuit, an operation device that outputs an operation command signal for moving the hydraulic operation unit, An idling stop control connected to the engine, the hydraulic circuit, and the operating device and stopping the engine when the engine is in an idling operation state, and the engine is restarted after the engine is stopped by the idling stop control. And a control device for performing engine restart control for starting. When the engine restart control is performed after the engine is stopped by the idling stop control, the control device disables the hydraulic circuit before restarting the engine, and then the hydraulic circuit When in an inoperable state, the engine is restarted in response to a predetermined trigger signal, and after restarting the engine, the hydraulic circuit is turned on when the operation command signal is not input from the operating device. Return to the operable state.

  After the engine stops, the hydraulic circuit is rendered inoperable, after which the engine is restarted and then restored to the operational state. Therefore, when the engine is restarted, the hydraulic circuit is inoperable and the hydraulic operating unit cannot move, so there is no possibility of the work machine moving unexpectedly.

  In a preferred embodiment, the work machine is provided with a lock device that outputs a lock instruction signal and an unlock instruction signal for the hydraulic circuit. The control device is in a state where the hydraulic circuit cannot be operated in response to the lock instruction signal from the lock device after the engine is stopped by the idling stop control and before the engine is restarted. To. The control device operates the hydraulic circuit in response to the lock release instruction signal from the lock device when the operation command signal is not input from the operation device after restarting the engine. Return to a possible state. Therefore, after the engine is stopped, the engine is not restarted unless the hydraulic circuit is locked by the locking device to make it inoperable. In addition, after the engine is restarted, as long as some operation command signal for moving the hydraulic operation unit is output from the operation device, the hydraulic circuit remains in an operable state even if the lock device instructs to release the lock. Does not return.

  In a preferred embodiment, a predetermined operation command signal from the operating device is used as the predetermined trigger signal. Therefore, after a predetermined operation command signal is output from the operating device after the engine is stopped, the engine is automatically restarted.

  In a preferred embodiment, the work vehicle includes a pilot pressure control device that controls a pressure of pilot pressure oil for controlling the hydraulic circuit. The control device controls the pilot pressure control device to make the hydraulic circuit inoperable by lowering the pilot pressure oil pressure below a predetermined operating threshold, and the pilot pressure oil pressure Is raised above the operating threshold value to return the hydraulic circuit to an operable state. Further, the control device gradually increases the pressure of the pilot pressure oil when returning the hydraulic circuit to an operable state. By this gradual pressure increase control, when the hydraulic circuit returns to the operable state, it is avoided that the hydraulic operation unit starts to operate suddenly.

  In a preferred embodiment, the work vehicle is provided with an alarm device that outputs a warning sound or an alarm to the outside of the work vehicle. When the control device receives the trigger signal when the hydraulic circuit is inoperable, the control device restarts the engine after a warning sound or warning is output from the warning device. Therefore, it is possible to notify people outside the work vehicle that the engine will be restarted, and to alert them to ensure safety.

  ADVANTAGE OF THE INVENTION According to this invention, when restarting an engine after the engine automatic stop by idling stop control, it is prevented that a work vehicle begins to start suddenly.

1 is a side view of a hydraulic excavator according to a first embodiment of the present invention. The figure which shows the whole schematic structure of the drive control system of the hydraulic shovel which concerns on 1st Embodiment. The flowchart explaining the process sequence of idling stop control and engine restart control in 1st Embodiment. The figure which shows the pressure | voltage rise curve of the pilot original pressure immediately after the engine restart in 1st Embodiment. The figure which shows the whole schematic structure of the drive control system of the hydraulic shovel which concerns on the 2nd Embodiment of this invention. The flowchart explaining the process sequence of idling stop control and engine restart control in 2nd Embodiment. The figure which shows the pressure | voltage rise curve of the pilot original pressure immediately after engine restart in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic excavator 2a Traveling hydraulic motor 3a Turning hydraulic motor 10 Boom cylinder 11 Arm cylinder 12 Bucket cylinder 13, 14 Work machine operation lever 15 Traveling operation lever 16 Engine 17 Hydraulic pump 18, 61 Operation valve assembly 19 Hydraulic operation part 20 Hydraulic circuit 21 Controller 21a First lever operation determination unit 21c Second lever operation determination unit 21d Lock lever operation position determination unit 27 Engine control device 28 Engine starter 33 Pilot pump 35, 36, 39, 55, 56, 59 Operation Part 37, 38, 40 pressure reducing valve 42, 51, 52, 53, 54, 57, 58 potentiometer 43 lock lever 46 electromagnetic proportional pressure control valve 60 lever operation discrimination part 62a proportional electromagnetic operation part

  Next, specific embodiments of the work vehicle according to the present invention will be described with reference to the drawings. Although the present embodiment is an example in which the present invention is applied to a hydraulic excavator as a work vehicle, it goes without saying that the present invention can also be applied to various other work vehicles such as bulldozers, dump trucks, cranes, forklifts, and the like. Yes.

[First Embodiment]
FIG. 1 is a side view of a hydraulic excavator according to the first embodiment of the present invention. FIG. 2 shows an overall schematic configuration of the drive control system for the hydraulic excavator.

  As shown in FIG. 1, a hydraulic excavator 1 according to the present embodiment includes a lower traveling body 2 having a traveling device 2b driven by a traveling hydraulic motor 2a, and a turning device 3 driven by a turning hydraulic motor 3a. The upper swing body 4 disposed on the lower traveling body 2 through the swing device 3, the work machine 5 attached to the front center position of the upper swing body 4, and the upper swing body 4 A cab 6 is provided at the front left position. Here, the work machine 5 includes a boom 7 that is swingably connected to the upper swing body 4, an arm 8 that is swingably connected to the boom 7, and a bucket 9 that is swingably connected to the arm 8. Have. The work machine 5 further includes hydraulic cylinders for moving the boom 7, the arm 8, and the bucket 9, that is, the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12. Further, on both sides of a driver's seat (not shown) in the cab 6, work machine operation levers 13 and 14 (see FIG. 2) for operating the turning operation of the upper swing body 4 and the bending and raising / lowering operations of the work machine 5 are provided. A pair of traveling operation levers 15 and 15 (see FIG. 2) for operating the traveling operation of the lower traveling body 2 are disposed in front of the driver seat.

  As shown in FIG. 2, the drive control system of the hydraulic excavator 1 includes a hydraulic circuit 20, in which the working pressure oil discharged from the hydraulic pump 17 driven by the engine 16 is supplied to the operation valve assembly 18. Is supplied to the hydraulic actuator 19 through Here, the hydraulic operation unit 19 is a block diagram of various hydraulic actuators such as the boom cylinder 10, the arm cylinder 11, the bucket cylinder 12, the traveling hydraulic motor 2a, and the turning hydraulic motor 3a. It is. The operation valve assembly 18 is an assembly of hydraulic pilot operated directional control valves 34 corresponding to the hydraulic actuators. By actuating the hydraulic circuit 20, the bending / extending / lowering operation of the work machine 5, the turning operation of the upper revolving body 4, and the traveling operation of the lower traveling body 2 are performed. Further, the drive control system includes a controller 21, which is a computer, for example, and is omitted from illustration, but by executing a predetermined control program, idling stop control, engine restart control, and other A central processing unit that performs arithmetic processing for control, a storage device that stores the control program and various tables and setting condition data used for the arithmetic processing, and an input / output device that inputs and outputs various signals described below. It has an output device.

  The engine 16 is, for example, a diesel engine, and the engine 16 is provided with a fuel injection pump 22 and a governor 23. A fuel control lever 23 a of the governor 23 is driven by a governor drive motor 24. The drive position of the fuel control lever 23 a is detected by a potentiometer 25, and the detection signal is input to the controller 21. Further, a fuel dial (not shown) is provided to set the throttle position (engine speed) of the engine 16, and a throttle signal (set speed signal) from a potentiometer (not shown) attached to the fuel dial is provided. Are input to the controller 21. The actual rotational speed of the engine 16 is detected by the rotational speed sensor 26, and the detection signal is also input to the controller 21.

  In the present embodiment, an engine control device 27 is mainly composed of a controller 21, a governor 23, a governor drive motor 24, a potentiometer 25, and a fuel dial. In this engine control device 27, the controller 21 is between the throttle signal (set rotation speed signal) input by the fuel dial described above and the actual rotation speed signal of the engine 16 detected by the rotation speed sensor 26. A deviation signal is generated, a drive signal having a voltage level satisfying a predetermined functional relationship with the deviation signal is generated, and the governor drive motor 24 is driven based on the drive signal.

  Here, as an example, if the fuel dial is set to the maximum position (FULL position), the throttle signal output from the potentiometer attached to the fuel dial indicates the maximum set speed, and the controller 21 A motor drive signal corresponding to the maximum set rotational speed is applied to the governor drive motor 24. Thereby, the governor drive motor 24 operates the fuel control lever 23a so that the highest speed regulation line is set, and as a result, the output horsepower and the engine speed of the engine 16 are automatically set. As another example, if a motor drive signal corresponding to the engine stop command is applied from the controller 21 to the governor drive motor 24, the governor drive motor 24 causes the fuel injection by the fuel injection pump 22 to be non-injected. Then, the fuel control lever 23a is operated, whereby the operation of the engine 16 is stopped.

  Further, the engine 16 is provided with an engine starting device 28 for starting the engine 16. The engine starter 28 includes a starter 29, a starter switch 30, a battery 31, a battery relay 32, and wiring for connecting these devices. In the engine starting device 28, when the operator operates the starter switch 30 to set it to the starting position, a starting signal flows to the starter 29 and power from the battery 31 is supplied to the starter 29 via the battery relay 32. Thus, the starter 29 drives the engine 16 so that the engine 16 is started. Similarly, when a start signal flows from the controller 21 to the starter 29, the starter 29 drives the engine 16 and the engine 16 is started.

  The hydraulic pump 17 is, for example, a variable displacement hydraulic pump, and a pilot pump (pilot pressure oil generator) 33 that is driven by the engine 16 and discharges pilot pressure oil is connected to the hydraulic pump 17. Yes. On the other hand, as described above, the operation valve assembly 18 includes various hydraulic actuators (travel hydraulic motor 2a, turning hydraulic motor 3a, boom cylinder 10, arm cylinder 11 and bucket cylinder 12) included in the hydraulic operation unit 19. Etc.) is a group of hydraulic pilot operated directional control valves 34,. Various pilot pressure oils output from pressure reducing valves 37, 38, and 40, which will be described later, are supplied to the direction control valves 34,..., 34, thereby moving the work implement 5, the upper swing body 4 and the lower traveling body 2. For this purpose, various oil path switching operations are performed.

  The work implement operation levers 13 and 14 are provided with pressure reducing valves (pilot pressure oil pressure adjusting output devices) 37 and 38 through operation units 35 and 36 for outputting various operation commands corresponding to various lever operations. Yes. Similarly, the travel operation levers 15 and 15 are provided with a pressure reducing valve (pilot pressure oil pressure adjusting output device) 40 through an operation unit 39 that outputs various operation commands corresponding to various lever operations. Pilot pressure oil discharged from the pilot pump 33 is supplied to the pressure reducing valves 37, 38, and 40 via an electromagnetic proportional pressure control valve 46 described later. The pressure reducing valves 37, 38, and 40 adjust the supplied pilot pressure oil based on various operation commands from the operation units 35, 36, 15, and 15, and adjust the adjusted pilot pressure oil to the operation valve assembly. Output to 18 The various pilot pressure oils output from the pressure reducing valves 37, 38, and 40 are input to the corresponding pilot pressure oil input ports in the operation valve assembly 18, whereby the various oil path switching operations described above are performed. Done. As a result, the turning operation of the upper swing body 4 and the bending and extending / lowering operations of the work machine 5 are performed by operating the work machine operation levers 13 and 14, and the lower traveling body is operated by operating the travel operation levers 15 and 15. 2 running operation will be performed.

Further, operation signals indicating the operation states of the work machine operation levers 13 and 14 and the travel operation levers 15 and 15 are transmitted via hydraulic switches 41,..., 41 attached to the pressure reducing valves 37, 38, 40, respectively. Are input to the controller 21. In the present embodiment, the operation signals input to the controller 21 include, for example, the following 12 types.
(1) A right turning operation signal corresponding to the right turning operation of the upper turning body 4 (2) A left turning operation signal corresponding to the left turning operation of the upper turning body 4 (3) A boom corresponding to the raising operation of the boom 7 Lifting operation signal (4) Boom lowering operation signal corresponding to the lowering operation of the boom 7 (5) Arm dumping operation signal corresponding to the operation of feeding the arm 8 forward (6) Arm excavation corresponding to the operation of pulling the arm 8 forward Operation signal (7) Bucket dump operation signal corresponding to the operation of feeding the bucket 9 forward (8) Bucket excavation operation signal corresponding to the operation of pulling the bucket 9 forward (9) Corresponding to the right forward traveling operation of the lower traveling body 2 The right forward travel operation signal (10) The right reverse travel operation signal corresponding to the right reverse travel operation of the lower travel body 2 (11) The left forward travel operation signal (1 corresponding to the left forward travel operation of the lower travel body 2 ) Left reverse travel operation signal corresponding to the left reverse running operation of the lower traveling body 2

  The controller 21 includes a first lever operation determination unit 21a as one function. The first lever operation determination unit 21a determines which lever operation is being performed based on the input operation signals (1) to (12). While the engine 16 is operating, the controller 21 determines whether or not there is any lever operation by the first lever operation determination unit 21a. The controller 21 has a timer 21b that counts a predetermined time length as another function. For the time length counted by the timer 21b, an operator can set an arbitrary time length from a control panel (not shown) arranged in the cab. In the idling stop control, the controller 21 counts the predetermined time length by the timer 21b while the engine 16 is in the idling operation state.

  The operation unit 35 coupled to the work implement operating lever 13 has an electric signal indicating whether a specific lever operation, for example, a boom raising operation, among the various lever operations of the work implement operating lever 13 is performed, that is, a boom raising operation. A potentiometer 42 for outputting a signal is attached. A boom raising operation signal from the potentiometer 42 is input to the controller 21. As another function, the controller 21 has a second lever operation determination unit 21c, which determines whether or not a boom raising operation is performed based on a boom raising operation signal input from the potentiometer 42. Determine. In the engine restart control after the engine 16 is stopped by the idling stop control, the controller 21 determines whether or not the boom raising operation is performed by the second lever operation determination unit 21c. In the present embodiment, “boom raising operation” is employed as the specific lever operation, but this is merely an example, and lever operations other than “boom raising operation” may be employed.

  A lock lever 43 is provided in the cab 6 for switching between a lock position for prohibiting the operation of the hydraulic circuit 20 and a lock release position for permitting the operation of the hydraulic circuit 20. When the lock lever 43 is in the unlock position, an ON signal (lock release position signal) from the limit switch 44 pushed by the lock lever 43 is input to the controller 21. The controller 21 has, as yet another function, a lock lever operation position determination unit 21d, which is configured such that the lock lever 44 is locked or unlocked based on a lock release position signal input from the limit switch 44. It is determined whether it is in either. In the engine restart control after the engine 16 is stopped by the idling stop control, the controller 21 determines the position of the lock lever 44 by the lock lever operation position determination unit 21d.

  An electromagnetic proportional pressure control valve (pressure control device) 46 is provided in the pilot pressure oil supply conduit 45 connecting the pilot pump 33 and the pressure reducing valves 37, 38, 40. In proportion to the magnitude of the control current input from the controller 21 to the electromagnetic proportional pressure control valve 46, the pressure of the pilot pressure oil supplied from the pilot pump 33 to the pressure reducing valves 37, 38, 40 is controlled.

  The pressure sensor 47 detects the discharge pressure of the hydraulic pump 17. A pressure detection signal from the pressure sensor 47 is input to the controller 21. The pressure sensor 48 detects the pressure of the pilot pressure oil supplied to the pressure reducing valves 37, 38, 40 via the electromagnetic proportional pressure control valve 46. The pressure detection signal from the pressure sensor 48 is input to the controller 21 and used as a feedback signal in the control of the pilot original pressure described later.

  Next, processing procedures of idling stop control and engine restart control performed by the controller 21 executing the control program will be described below with reference to the flowchart of FIG. In FIG. 3, the control in steps S1 to S4 corresponds to idling stop control, and the control in steps S5 to S11 corresponds to engine restart control.

  As shown in FIG. 3, in step S1, the controller 21 determines whether or not the engine 16 is in an idling operation state. That is, when any of the operation signals (1) to (12) is input to the controller 21, that is, any of the work implement 5, the upper swing body 4, and the lower traveling body 2 operates. When the engine 21 is in operation, the controller 21 determines that the engine 16 is not in the idling operation state, and continues the operation of the engine 16 (step S2). On the other hand, when none of the operation signals (1) to (12) is input to the controller 21, that is, all of the work implement 5, the upper swing body 4 and the lower traveling body 2 are operating. If not, it is determined that the engine 16 is in the idling operation state.

  When it is determined in step S1 that the engine 16 has entered the idling operation state, the controller 21 starts counting for a predetermined time (for example, about several tens of seconds) by the timer 21b, and thereafter, the idling operation state continues for the predetermined time. It is determined whether or not the operation has been continued (S3). As a result, when the duration of the idling operation state reaches the predetermined time, the controller 21 transmits a motor drive signal corresponding to the engine stop command to the governor drive motor 24 to stop the engine 16 (S4). .

  After the engine 16 is stopped in step S4, the controller 21 locks the position of the lock lever 43 based on the presence / absence of the unlock position signal input from the limit switch 44 by the lock lever operation position determination unit 21d. It is determined whether it is in the position or the unlocked position (S5). If it is determined in step S5 that the position of the lock lever 43 is in the unlock position, the controller 21 stands by. On the other hand, if it is determined in step S5 that the position of the lock lever 43 is in the locked position, the controller 21 supplies the pilot pressure oil supplied to the pressure reducing valves 37, 38, 40 through the electromagnetic proportional pressure control valve 46. The pressure (hereinafter referred to as “pilot source pressure”) (Pc) is the lowest hydraulic pressure (hereinafter referred to as “operation threshold value” of the operation valve assembly 18) at which various oil path switching operations can be performed in the operation valve assembly 18 ( A control current is output to the electromagnetic proportional pressure control valve 46 so as to be a predetermined value (Pa) smaller than (Pt) (S6). As a result, even if the operation levers 13, 14, 15 are operated, the work machine 5, the upper swing body 4 and the lower traveling body 2 are not driven. In other words, the operation of the hydraulic circuit 20 is prohibited. However, the value (Pa) of the pilot original pressure (Pc) at this time is the lowest hydraulic pressure at which the hydraulic switches 41,..., 41 connected to the outputs of the pressure reducing valves 37, 38, 40 can operate (hereinafter referred to as the hydraulic switch 41). ,..., 41 (referred to as “actuation threshold”) (Ps). Therefore, various operations performed on the operation levers 13, 14, and 15 are detected by the hydraulic switches 41,. Recognized by the controller 21.

  Only when the operation of the hydraulic circuit 20 is prohibited in response to the lock position of the lock lever 43 in steps S5 and S6 described above, the control proceeds to step S7. In step S7, the controller 21 determines whether or not a specific lever operation, that is, a lever operation related to the boom raising operation, is performed based on the boom raising operation signal from the potentiometer 42 by the second lever operation determination 21c. Is discriminated (S7). When it is determined in step S7 that the specific lever operation is being performed, the controller 21 transmits a start signal to the starter 29 to start the engine 16 (S8). Thus, when the engine 16 is restarted in response to a specific lever operation, the operation of the hydraulic circuit 20 has already been prohibited by the above-described step S6 (Pc <Pt). Therefore, the corresponding oil passage switching operation is not performed by the operation valve assembly 18. Therefore, there is no possibility that the excavator 1 starts to move unexpectedly when the engine is restarted. At this time, since the pilot original pressure (Pc) is higher than the operation threshold value (Ps) of the hydraulic switches 41,..., 41 (Pc = Pa> Ps), the controller 21 uses the first lever operation determination unit 21a. The presence or absence of various lever operations after engine startup can be determined.

  After restarting the engine 16 in step S8, the controller 21 determines whether or not the operation signals (1) to (12) from the hydraulic switches 41,. Based on this, it is determined whether or not all the operation levers 13, 14, 15, 15 are in the neutral position (no lever operation for moving the excavator 1 is performed) (S9). If it is determined in step S9 that any of the operation levers 13, 14, 15, 15 is not in the neutral position (some lever operation for moving the excavator 1 is being performed), the controller 21 Wait. On the other hand, if it is determined in step S9 that all the operation levers 13, 14, 15, 15 are in the neutral position, the controller 21 controls the limit lever 44 from the limit switch 44 by the lock lever operation position determination unit 21d. Based on whether or not the unlock position signal is input, it is determined whether the lock lever 43 is in the lock position or the unlock position (S10). If it is determined in step S10 that the lock lever 43 is in the locked position, the control by the controller 21 returns to step S9. On the other hand, if it is determined in step S10 that the lock lever 43 is in the unlock position, the controller 21 outputs a control current to the electromagnetic proportional pressure control valve 46 (S11), and the pilot original pressure ( Pc) is raised with a curve as shown in FIG. As a result, as shown in FIG. 4, the pilot original pressure (Pc) rapidly rises from the predetermined value (Pa) to the operating threshold value (Pt) of the operating valve assembly 18, and thereafter, the operating threshold value (Pt) ) Slowly and gradually increase to a higher maximum set pressure value (Pe). The pilot original pressure (Pc) is increased in a state where the rotational speed of the engine 16 is equal to or higher than a predetermined rotational speed and the discharge pressure of the pilot pump 33 rises to a necessary and sufficient level. As the pilot original pressure (Pc) increases, the state of the operation valve assembly 18 shifts to a state where the oil passage switching operation can be performed (that is, the state of the hydraulic circuit 20 shifts to an operable state). . Therefore, when the operation levers 13, 14, 15, and 15 are operated, the operation of the hydraulic excavator 1 (hydraulic operation unit 19) starts.

  Thus, after the engine is restarted, only when all the operation levers are in the neutral position (that is, no lever operation for moving the excavator 1 is performed), the controller 21 can lock the lock lever 43. In response to the release of the lock, the pilot original pressure (Pc) is increased to the maximum set pressure value (Pe) higher than the operation threshold value (Pt) of the operation valve assembly 18 and the hydraulic circuit 20 is operable. To migrate. Therefore, there is no possibility that the excavator 1 (hydraulic operating portion 19) starts unexpectedly when the engine 16 restarts in response to a specific lever operation. Further, since the pilot original pressure (Pc) is increased gradually from the operating threshold value (Pt) to the maximum set pressure value (Pe), no matter what lever operation is performed immediately after unlocking, the hydraulic pressure The excavator 1 (hydraulic operating unit 19) starts to operate at a low speed, and a rapid high-speed operation at the start of the operation is avoided.

[Second Embodiment]
FIG. 5 shows an overall schematic configuration of a drive control system for a hydraulic excavator according to the second embodiment of the present invention. In the present embodiment, the same or similar elements as those in the first embodiment are denoted by the same reference numerals, and redundant description thereof will be omitted. In the following, different parts from the first embodiment will be described. The explanation will be focused on. The basic configuration of the hydraulic excavator is as already described with reference to FIG.

  In the present embodiment, the operation units 55 and 56 convert various operation commands corresponding to various lever operations of the work machine operation levers 13 and 14 into electric signals (operation signals) by the potentiometers 51, 52, 53, and 54. To the controller 21. The operation unit 59 converts various operation commands corresponding to various lever operations of the travel operation levers 15 and 15 into electric signals (operation signals) by the potentiometers 57 and 58, and outputs them to the controller 21. The controller 21 includes a lever operation determination unit 60, which determines whether or not various lever operations are performed based on various input operation signals. Examples of the type of operation signal input to the controller 21 include the above-described operation signals (1) to (12).

  In addition, the operation valve assembly 61 controls the supply of the hydraulic pressure oil discharged from the hydraulic pump 17 to the hydraulic operation unit 19. A plurality of electromagnetic valves are provided corresponding to the respective hydraulic actuators (travel hydraulic motor 2a, turning hydraulic motor 3a, boom cylinder 10, arm cylinder 11, bucket cylinder 12) of the hydraulic operation unit 19. It is an assembly of hydraulic pilot operated directional control valves 62. Each electromagnetic / hydraulic pilot operated directional control valve 62 includes a proportional electromagnetic operating unit 62a and a hydraulic pilot operating unit 62b. When any of the operation signals from the potentiometers 51, 52, 53, 54, 57, 58 described above is input to the controller 21, the controller 21 converts the operation current based on the input operation signal into the corresponding direction. It outputs to the proportional electromagnetic operation part 62a of the control valve 62. In each operation valve 62, the proportional electromagnetic operation unit 62a adjusts the pilot pressure oil supplied from the pilot pump 33 in proportion to the operation current from the controller 21, and the adjusted pilot pressure oil is the hydraulic pilot. A predetermined oil path switching operation for controlling the corresponding hydraulic actuator is performed in accordance with the pilot pressure oil output to the operation unit 62b and output to the hydraulic pilot operation unit 62b.

  Next, the processing procedure of idling stop control and engine restart control performed by the controller 21 will be described with reference to the flowchart of FIG. In FIG. 6, steps R1 to R4 correspond to idling stop control, and steps R5 to R11 correspond to engine restart control.

  As shown in FIG. 6, in step R <b> 1, the controller 21 determines whether or not the engine 16 is in an idling operation state based on the presence / absence of various operation signals (1) to (12). When any of the various operation signals (1) to (12) is input, the controller 21 determines that the engine 16 is not in the idling operation state, and continues the operation of the engine 16 in step R2. On the other hand, the controller 21 determines that the engine 16 is in the idling operation state when none of the various operation signals (1) to (12) is input.

  In step R1, when the engine 16 enters the idling operation state, the controller 21 starts counting a predetermined time (for example, about several tens of seconds) by the timer 21b in step R3, and thereafter the idling operation state is predetermined. Determine if it has continued over time. When the count value by the timer 21b does not exceed the predetermined time, the controller 21 continues the operation of the engine 16 (R2). On the other hand, when the count value by the timer 21b reaches the predetermined time, the controller 21 transmits a motor drive signal corresponding to the engine stop command to the governor drive motor 24 in step R4 to stop the engine 16.

  After the engine 16 is stopped in step R4, the controller 21 causes the lock lever operation position determination unit 21d to move the lock lever 43 to the locked position or not based on the presence / absence of an unlock position signal input from the limit switch 44. It is determined which position is the unlock position (R5). If it is determined in step R5 that the lock lever 43 is in the unlock position, the controller 21 stands by. On the other hand, if it is determined in step R5 that the lock lever 43 is in the locked position, the controller 21 sets the value of the control current output to the electromagnetic proportional pressure control valve 46 to zero (R6). In step R6, the pressure of the pilot pressure oil (hereinafter referred to as “pilot source pressure”) (Pc) supplied from the pilot pump 33 to each electromagnetic / hydraulic pilot operated directional control valve 62 through the electromagnetic proportional pressure control valve 46 is zero. Therefore, the hydraulic circuit 20 cannot drive any hydraulic actuators of the hydraulic operation unit 19.

  Thereafter, the controller 21 determines whether any of various lever operations for moving the excavator 1 is performed based on the presence / absence of an operation signal from the potentiometers 51, 52, 53, 54, 57, 58. Is discriminated (R7). When it is determined in step R7 that any lever operation is being performed, the controller 21 transmits a start signal to the starter 29 to start the engine 16 (R8). As described above, after the engine 16 is automatically stopped by the idling stop control, when any operation is performed on the work implement operation levers 13 and 14 or the travel operation levers 15 and 15, the engine is automatically restarted. However, at this time, the pilot original pressure (Pc) is already controlled to zero by the above-described step R6, so that the oil passage switching operation of the operation valve assembly 61 cannot be performed. Therefore, even if the engine 16 is restarted, there is no possibility that the excavator 1 (hydraulic operating portion 19) starts to move unexpectedly.

  After the engine 16 is restarted in step R8, the controller 21 performs work based on the presence / absence of the operation signals (1) to (12) from the potentiometers 51, 52, 53, 54, 57, 58. It is determined whether or not the machine operating levers 13 and 14 and the traveling operating levers 15 and 15 are all in the neutral position (that is, no lever operation for moving the excavator 1 is performed) (R9). In step R9, when it is determined that any of the operation levers 13, 14, 15, and 15 is not in the neutral position (that is, some lever operation for moving the excavator 1 is performed), the controller 21 waits. To do. At this time, as described above, since the pilot original pressure (Pc) is controlled to zero, the hydraulic excavator 1 remains stationary regardless of any lever operation. If it is determined in step R9 that all the operation levers 13, 14, 15, 15 are in the neutral position, the controller 21 determines whether the lock release position signal is input from the limit switch 44 or not. The operation position determination unit 21d determines whether the lock lever 43 is in the locked position or the unlocked position (R10). If it is determined in step R10 that the lock lever 43 is in the locked position, the control by the controller 21 returns to step R9. On the other hand, if it is determined in step R10 that the lock lever 43 is in the unlocked position, the controller 21 controls the pilot original pressure (Pc) so as to increase along the curve shown in FIG. A current is output to the electromagnetic proportional pressure control valve 46 (R11). As a result, as shown in FIG. 7, the pilot original pressure (Pc) is zero, and the minimum hydraulic pressure at which the oil passage switching operation of the operation valve assembly 18 can be performed (hereinafter referred to as the “operation threshold” of the operation valve assembly 18). ) To (Pt) in a short time, and then gradually increases gradually to a maximum set pressure value (Pe) higher than the operating threshold value (Pt). Note that this pilot original pressure increasing operation is performed in a state where the engine 16 has a rotational speed equal to or higher than a certain rotational speed and the discharge pressure of the pilot pump has risen sufficiently and sufficiently. As a result of the increase of the pilot original pressure (Pc), the oil passage switching operation of the operation valve assembly 61 can be performed, and the hydraulic excavator 1 (hydraulic operating portion 19) can be moved.

  Thus, after the engine is restarted, only when all the operation levers 13, 14, 15, and 15 are in the neutral position operation (that is, the lever operation for moving the excavator 1 is not performed at all). In response to the unlocking operation of the lock lever 43, the controller 21 shifts the hydraulic circuit 20 from an inoperable state to an operable state. Therefore, when the hydraulic circuit 20 becomes operable by the unlocking operation, there is no possibility that the excavator 1 (hydraulic operating portion 19) starts to move unexpectedly. Further, since the pilot original pressure (Pc) is gradually and gradually increased from the operating threshold value (Pt) to the maximum set pressure value (Pe), no matter what lever operation is performed immediately after unlocking, the hydraulic excavator 1 (hydraulic actuator 19) starts to operate at a low speed, and a rapid high-speed operation at the start of the operation is avoided. Regardless of how the operating levers 13, 14, 15, 15 are operated, the hydraulic operation unit 19 starts operating at a low speed, and a rapid high-speed operation at the start of the operation is avoided.

  As a modification, it is shown between the step S6 and step S7 shown in the flowchart of FIG. 3 in the above-described first embodiment, or in the flowchart of FIG. 6 in the above-described second embodiment. Between step R6 and step R7, a step is performed to check whether the operator has sounded a horn (not shown) of the excavator 1, and the engine 16 is restarted unless the horn is sounded in advance. You may control so that it may not. Alternatively, people who are near the outside of the excavator 1 or boarding the excavator 1 using an appropriate alarm method that automatically sounds an alarm before restarting the engine The operator may be automatically notified that the engine restart operation will be performed from now on. According to these modified examples, a warning sound or an alarm is output to the inside or outside of the excavator 1 immediately before the engine is restarted, so that the people who are near the excavator 1 or the operators who are on the excavator 1 can It is possible to call attention for safety in preparation for restart.

  As mentioned above, although embodiment of this invention was described, this embodiment is only the illustration for description of this invention, and is not the meaning which limits the scope of the present invention only to this embodiment. The present invention can be implemented in various other modes without departing from the gist thereof.

Claims (6)

An engine (17), a hydraulic circuit (20) driven by the engine, a hydraulic actuator (19) driven by the hydraulic circuit, and an operating device for outputting an operation command signal for moving the hydraulic actuator (13, 14, 15), an idling stop control connected to the engine, the hydraulic circuit, and the operating device, and stopping the engine when the engine is in an idling operation state, and the engine by the idling stop control. A control device (21) for performing engine restart control for restarting the engine after stopping the operation, a lock instruction signal for prohibiting the operation of the hydraulic circuit, and an unlock instruction signal for permitting the operation of the hydraulic circuit. In a work vehicle including a lock device (43) for outputting, the control device includes the idling strap. When the engine restart control is performed after the engine is stopped by the pop-up control, the engine waits until the lock instruction signal is received from the lock device (43) before the engine is restarted. 43), the hydraulic circuit is made inoperable in response to the lock instruction signal from S43 (S6, R6). When the hydraulic circuit is inoperable by the lock instruction signal , a predetermined trigger signal is received. The engine is restarted (S7, S8, R7, R8), and after the engine is restarted, when the operation command signal is not input from the operation device, the lock device (43) A work vehicle characterized by returning the hydraulic circuit to an operable state in response to a lock release instruction signal (S9, S11, R9, R11). The work vehicle according to claim 1, wherein the predetermined trigger signal is a predetermined operation command signal from the operating device. A pilot pressure control device (46) for controlling the pressure of the pilot pressure oil for controlling the hydraulic circuit; and the control device controls the pilot pressure control device (46) to control the pilot pressure oil. The hydraulic circuit is rendered inoperable by lowering the pressure below a predetermined operating threshold, and the hydraulic circuit is returned to an operable state by raising the pressure of the pilot pressure oil above the operating threshold. The work vehicle according to claim 1. The work vehicle according to claim 3 , wherein the control device gradually increases the pressure of the pilot pressure oil when returning the hydraulic circuit to an operable state. An alarm device that outputs a warning sound or a warning is further provided, and when the control device receives the trigger signal when the hydraulic circuit is inoperable, the warning device outputs the warning sound or the warning. The work vehicle according to claim 1, wherein the engine is restarted after a short time. An engine (17), a hydraulic circuit (20) driven by the engine, a hydraulic actuator (19) driven by the hydraulic circuit, and an operating device for outputting an operation command signal for moving the hydraulic actuator (13, 14, 15) and an idling stop in a work vehicle provided with a lock instruction signal for prohibiting the operation of the hydraulic circuit and a lock device (43) for outputting an unlock instruction signal for permitting the operation of the hydraulic circuit. In the control method for restarting the engine after the engine is stopped by control, the control device waits until the lock instruction signal is received from the lock device (43) before the engine is restarted. the step of said lock in response to an instruction signal inoperative the hydraulic circuit state from (43) and (S6, R6), wherein A step (S7, S8, R7, R8) of receiving the predetermined trigger signal and restarting the engine when the pressure circuit is in an inoperable state; A step (S9, S11, R9, R11) of returning the hydraulic circuit to an operable state in response to the unlocking instruction signal from the locking device (43) when no operation command signal is also input; An engine restart control method comprising:

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