Working machine

Abstract

To provide a work machine allowing a work device to carry out motions following an operation command by suppressing divergence between a temperature of pressured oil of a main circuit supplied to a hydraulic actuator and a temperature of pressured oil of a pilot circuit acting on a control valve.SOLUTION: A hydraulic shovel 1 provided with a work device 13 of a hydraulic driving type comprises: a first pipe line 701 as a warming pipe line; a second pipe line 702 as a cooling pipe line; a direction selector valve 70 for switching a direction of a pilot pressured oil; and a controller 5 for controlling the direction selector valve 70, wherein the controller 5 outputs to the direction selector valve 70 a first switching command signal instructing a switch to a warming position 70A when a pilot oil temperature Tp is lower than a hydraulic oil temperature, and outputs to the direction selector valve 70 a second switching command signal instructing a switch to a cooling position 70B when the pilot oil temperature Tp is higher than the hydraulic oil temperature.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a working machine equipped with a hydraulic-driven working device.

Background Art

[0002] A working machine typified by a hydraulic excavator is equipped with a working device that performs, for example, excavation work such as excavating earth and sand or minerals, or horizontal pulling work for leveling the ground. The working device is mainly hydraulically driven, and is driven by supplying pressurized oil discharged from a hydraulic pump to a hydraulic actuator. At this time, when the temperature of the pressurized oil is low, the viscosity of the pressurized oil increases, and the responsiveness of the hydraulic actuator to an operation command becomes slow. On the other hand, when the temperature of the pressurized oil is high, the viscosity of the pressurized oil decreases, and the responsiveness of the hydraulic actuator to an operation command becomes fast. Thus, since the responsiveness of the hydraulic actuator is affected by the oil temperature of the main circuit, and the responsiveness in the command signal is affected by the oil temperature of the pilot circuit, a deviation occurs between the actual operation of the working device and the operation intended by the operator, leading to a decrease in work efficiency. Therefore, temperature management of the pressurized oil becomes important.

[0003] For example, Patent Document 1 discloses an oil temperature sensor that detects the temperature of pressurized oil flowing through a hydraulic actuator circuit that drives a working hydraulic actuator, a cooling position for cooling the pressurized oil, an intermediate position where neither cooling nor warm-up of the pressurized oil is performed, a warm-up position for warming up the pressurized oil, a switching valve provided therewith, and a controller that switches and controls the position of the switching valve according to the temperature of the pressurized oil detected by the oil temperature sensor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technology described in Patent Document 1, only the temperature of the pressure oil in the main circuit supplied to the hydraulic actuator for work is monitored, and cooling and warm-up are performed. For the pressure oil in the pilot circuit acting on the control valve, temperature control is not performed.

[0006] In this case, if the temperature of the pressure oil in the pilot circuit is higher than the temperature of the pressure oil in the main circuit, the viscosity of the pressure oil in the pilot circuit is low and the viscosity of the pressure oil in the main circuit is high. Therefore, while the control valve performs an operation following the operation command, it becomes difficult for the pressure oil in the main circuit to flow into the control valve. Also, if the temperature of the pressure oil in the pilot circuit is lower than the temperature of the pressure oil in the main circuit, the viscosity of the pressure oil in the pilot circuit is high and the viscosity of the pressure oil in the main circuit is low. Therefore, the operation of the control valve cannot follow the operation command and is delayed. This is a problem that occurs when there is a deviation in the oil temperature between the main circuit and the pilot circuit even when they are warmed up to a certain extent.

[0007] This problem is particularly likely to occur in a working machine equipped with a machine control function that controls the working device to automatically operate along the target construction surface. For example, when a hydraulic excavator automatically performs a horizontal pulling operation on the ground based on an operation command by machine control, the working device cannot perform an operation following the operation command from the machine control, and sinking occurs with respect to the target construction surface, resulting in a wavy construction surface.

[0008] Therefore, an object of the present invention is to provide a working machine capable of suppressing the deviation between the temperature of the pressure oil in the main circuit supplied to the hydraulic actuator and the temperature of the pressure oil in the pilot circuit acting on the control valve, and enabling the working device to perform an operation following the operation command.

Means for Solving the Problems

[0009] In order to achieve the above object, the present invention provides a working machine including a machine body, a working device attached to the machine body, a hydraulic actuator for driving the working device, a main pump for supplying pressure oil to the hydraulic actuator, a control valve for controlling the flow rate of the pressure oil guided from the main pump to the hydraulic actuator, and a pilot pump for supplying pilot pressure oil to a pilot oil chamber of the control valve. The working machine further includes a first temperature sensor for detecting the main circuit oil temperature in a main circuit including the control valve, a second temperature sensor for detecting the pilot oil temperature which is the temperature of the pilot pressure oil, and a and leads to the pilot oil chamber warming-up pipeline the first pipeline as for warming up the pilot pressure oil discharged from the pilot pump and leads to the pilot oil chamber cooling pipeline the second pipeline as and a third pipeline that leads the pilot pressure oil discharged from the pilot pump to the pilot oil chamber without performing temperature adjustment; a direction switching valve for switching the direction of the pilot pressure oil guided from the pilot pump to the pilot oil chamber, and a controller for controlling the direction switching valve. The direction switching valve includes a warming-up position for guiding the pilot pressure oil discharged from the pilot pump to the pilot oil chamber through the First pipeline, a cooling position for guiding the pilot pressure oil discharged from the pilot pump to the pilot oil chamber through the Second pipeline, and a neutral position for guiding the pilot pressure oil discharged from the pilot pump to the Via the third pipeline pilot oil chamber. The controller outputs a first switching command signal for instructing switching to the warming-up position to the direction switching valve when the pilot oil temperature detected by the second temperature sensor is lower than the main circuit oil temperature detected by the first temperature sensor, and outputs a second switching command signal for instructing switching to the cooling position to the direction switching valve when the pilot oil temperature detected by the second temperature sensor is higher than the main circuit oil temperature detected by the first temperature sensor. and the absolute value of the difference between the main circuit oil temperature detected by the first temperature sensor and the pilot oil temperature detected by the second temperature sensor is greater than a predetermined threshold value This is the gist of the present invention. and the absolute value is greater than the predetermined threshold value and when the absolute value is less than or equal to the predetermined threshold value, a third switching command signal for commanding switching to the neutral position is output to the direction switching valve characterized by the above.

Advantages of the Invention

[0010] ​According to the present invention, it is possible to suppress the deviation between the temperature of the pressure oil in the main circuit supplied to the hydraulic actuator and the temperature of the pressure oil in the pilot circuit acting on the control valve, and the working device can perform an operation following an operation command. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

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Figure 5

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Figure 8

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Figure 11

Figure 12

Best Mode for Carrying Out the Invention

[0012] Hereinafter, as an aspect of the working machine according to each embodiment of the present invention, a crawler-type hydraulic excavator will be described.

[0013] <Overall Configuration of Hydraulic Excavator 1> First, the overall configuration of the hydraulic excavator 1 will be described with reference to FIG. 1.

[0014] FIG. 1 is an external side view showing a configuration example of the hydraulic excavator 1 according to each embodiment of the present invention.

[0015] The hydraulic excavator 1 includes a self-propelled crawler-type traveling body 11, a slewing body 12 rotatably provided above the traveling body 11, and a working device 13 attached to the slewing body 12 for performing operations such as excavation and leveling.

[0016] The traveling body 11 includes a pair of crawlers 111 extending in the traveling direction of the machine body, and a pair of traveling motors 112 for driving the pair of crawlers 111. The machine body is moved by rotating the pair of crawlers 111 in contact with the ground by the driving force of the pair of traveling motors 112. The pair of traveling motors 112 are mounted on the traveling body 11 corresponding to each of the pair of crawlers 111, and can rotate the pair of crawlers 111 independently in the forward and reverse directions by driving independently of each other. In FIG. 1, only one of the pair of crawlers 111 is shown.

[0017] The slewing body 12 includes a slewing frame 21 constituting a main body frame as a base, a cab 22 on which an operator rides, a counterweight 23 for maintaining the balance with the working device 13 so that the hydraulic excavator 1 does not tip over, and a machine room 24 for housing various devices for driving the hydraulic excavator 1 inside.

[0018] On the slewing frame 21, the operator's cab 22 is placed at the front, the counterweight 23 is placed at the rear end, and the machine room 24 is placed between the operator's cab 22 and the counterweight 23, respectively. Further, on one side of the operator's cab 22 at the front of the slewing frame 21, the working device 13 is attached.

[0019] The working device 13 is hydraulically driven and includes a boom 31 whose base end is rotatably attached to the slewing frame 21, an arm 33 rotatably attached to the tip of the boom 31, and a bucket 35 rotatably attached to the tip of the arm 33.

[0020] The boom 31 is driven by a boom cylinder 32. One end of the boom cylinder 32 is connected to the slewing frame 21, and the other end is connected to the boom 31. By the inflow and outflow of hydraulic oil, the rod 320 expands and contracts to rotate the boom 31 vertically (pitch) with respect to the slewing body 12.

[0021] The arm 33 is driven by an arm cylinder 34. One end of the arm cylinder 34 is connected to the boom 31, and the other end is connected to the arm 33. By the inflow and outflow of hydraulic oil, the rod 340 expands and contracts to rotate the arm 33 back and forth with respect to the boom 31.

[0022] The bucket 35 is driven by a bucket cylinder 36. One end of the bucket cylinder 36 is connected to the arm 33, and the rod side is connected to the bucket 35. By the inflow and outflow of hydraulic oil, the rod 360 expands and contracts to rotate the bucket 35 back and forth with respect to the arm 33.

[0023] The bucket 35 is a working tool for scooping up loads such as earth and sand and unloading the loads at a predetermined position or leveling the ground. Note that this bucket 35 can be changed to various attachments such as a grapple for gripping wood, rocks, waste, etc., or a breaker for excavating bedrock. Thereby, the hydraulic excavator 1 can perform various operations including excavation and crushing using an attachment suitable for the work content.

[0024] The boom cylinder 32, the arm cylinder 34, and the bucket cylinder 36 are all aspects of a hydraulic actuator that drives the working device 13. Below, the configuration of the hydraulic drive system for driving the working device 13 will be described for each embodiment.

[0025] <First Embodiment> The hydraulic drive system 4 according to the first embodiment of the present invention will be described with reference to FIGS. 2 to 5.

[0026] (Overall Configuration of Hydraulic Drive System 4) First, the overall configuration of the hydraulic drive system 4 will be described with reference to FIGS. 2 and 3.

[0027] FIG. 2 is a circuit diagram showing a configuration example of the hydraulic drive system 4 according to the first embodiment. FIG. 3 is a circuit diagram showing a configuration example of the machine control valve unit 6 in FIG. 2.

[0028] The hydraulic drive system 4 includes an engine 40, a hydraulic oil tank 40A, a main pump 41, a pilot pump 42, a boom control valve 43, an arm control valve 44, a bucket control valve 45, a boom pilot pressure generating device 46, an arm pilot pressure generating device 47, a bucket pilot pressure generating device 48, a gate lock valve 49, a controller 5, a machine control valve unit 6, and a shuttle block 410A.

[0029] The engine 40 is controlled by the controller 5 and starts and stops when the operator operates a key switch 220 provided in the cab 22.

[0030] When the operator operates the key switch 220 to the start position, the key switch 220 outputs a start signal to the controller 5, and the controller 5 outputs a control signal related to starting to the engine based on the start signal from the key switch 229. Thereby, the engine 40 starts.

[0031] When the operator operates the key switch 220 to the stop position, the key switch 220 outputs a stop signal to the controller 5, and the controller 5 outputs a control signal for stopping to the engine based on the stop signal from the key switch 220. As a result, the engine 40 stops.

[0032] The main pump 41 is driven by the engine 40, sucks up the hydraulic oil stored in the hydraulic oil tank 40A, and supplies hydraulic oil to each of the boom cylinder 32, the arm cylinder 34, and the bucket cylinder 36. The main pump 41 is a variable displacement hydraulic pump, and its discharge flow rate is controlled by a regulator 410.

[0033] Also, on the discharge side of the main pump 41, a main relief valve 41A is provided to keep the pressure of the hydraulic oil discharged from the main pump 41 constant. Therefore, when the pressure of the hydraulic oil discharged from the main pump 41 exceeds a predetermined relief pressure, the excess hydraulic oil returns to the hydraulic oil tank 40A.

[0034] The pilot pump 42 is driven by the engine 40, sucks up the hydraulic oil stored in the hydraulic oil tank 40A, and supplies pilot pressure oil to each of the boom control valve 43, the arm control valve 44, and the bucket control valve 45. The pilot pump 42 is a fixed displacement hydraulic pump and discharges hydraulic oil with a preset predetermined discharge flow rate as pilot pressure oil.

[0035] Also, on the discharge side of the pilot pump 42, similarly to the discharge side of the main pump 41, a pilot relief valve 42A is provided to keep the pressure of the pilot pressure oil discharged from the pilot pump 42 constant. Therefore, when the pressure of the pilot pressure oil discharged from the pilot pump 42 exceeds a predetermined relief pressure, the excess pilot pressure oil returns to the hydraulic oil tank 40A.

[0036] The boom control valve 43 is provided between the main pump 41 and the boom cylinder 32, and controls the direction and flow rate of the hydraulic oil guided from the main pump 41 to the boom cylinder 32. The boom control valve 43 has three switching positions: a first switching position 431, a second switching position 432, and a neutral position 430.

[0037] The first switching position 431 connects the main pump 41 and the bottom chamber 321 of the boom cylinder 32, and connects the rod chamber 322 of the boom cylinder 32 and the hydraulic oil tank 40A. Therefore, when the boom control valve 43 is switched to the first switching position 431, the hydraulic oil discharged from the main pump 41 flows into the bottom chamber 321 of the boom cylinder 32, and the hydraulic oil in the rod chamber 322 of the boom cylinder 32 is discharged into the hydraulic oil tank 40A. As a result, the rod 320 of the boom cylinder 32 extends, and the boom 31 rotates upward with respect to the slewing body 12.

[0038] The second switching position 432 connects the main pump 41 and the rod chamber 322 of the boom cylinder 32, and connects the bottom chamber 321 of the boom cylinder 32 and the hydraulic oil tank 40A. Therefore, when the boom control valve 43 is switched to the second switching position 432, the hydraulic oil discharged from the main pump 41 flows into the rod chamber 322 of the boom cylinder 32, and the hydraulic oil in the bottom chamber 321 of the boom cylinder 32 is discharged into the hydraulic oil tank 40A. As a result, the rod 320 of the boom cylinder 32 contracts, and the boom 31 rotates downward with respect to the slewing body 12.

[0039] The neutral position 430 shuts off the connection between the main pump 41 and the boom cylinder 32 and the connection between the boom cylinder 32 and the hydraulic oil tank 40A, respectively. Therefore, when the boom control valve 43 is switched to the neutral position 430, the inflow and outflow of the hydraulic oil in the boom cylinder 32 stop. As a result, the telescoping operation of the rod 320 of the boom cylinder 32 stops, and the vertical rotation operation of the boom 31 with respect to the slewing body 12 also stops.

[0040] The boom control valve 43 is provided with a pair of pilot oil chambers 43A and 43B to which pilot pressure oil is supplied. The switching between the first switching position 431, the second switching position 432, and the neutral position 430 in the boom control valve 43 is performed by the stroke of an internal spool according to the pressure of the pilot pressure oil (pilot pressure) supplied to the pair of pilot oil chambers 43A and 43B.

[0041] The arm control valve 44 is provided between the main pump 41 and the arm cylinder 34, and controls the direction and flow rate of the hydraulic oil guided from the main pump 41 to the arm cylinder 34. Similar to the boom control valve 43, the arm control valve 44 has three switching positions: a first switching position 441, a second switching position 442, and a neutral position 440.

[0042] The first switching position 441 connects the main pump 41 and the bottom chamber 341 of the arm cylinder 34, and connects the rod chamber 342 of the arm cylinder 34 and the hydraulic oil tank 40A. Therefore, when the arm control valve 44 is switched to the first switching position 441, the hydraulic oil discharged from the main pump 41 flows into the bottom chamber 341 of the arm cylinder 34, and the hydraulic oil in the rod chamber 342 of the arm cylinder 34 is discharged to the hydraulic oil tank 40A. As a result, the rod 340 of the arm cylinder 34 extends, and the arm 33 rotates upward with respect to the boom 31 (crowd operation).

[0043] The second switching position 442 connects the main pump 41 and the rod chamber 342 of the arm cylinder 34, and connects the bottom chamber 341 of the arm cylinder 34 and the hydraulic oil tank 40A. Therefore, when the arm control valve 44 is switched to the second switching position 442, the hydraulic oil discharged from the main pump 41 flows into the rod chamber 342 of the arm cylinder 34, and the hydraulic oil in the bottom chamber 341 of the arm cylinder 34 is discharged to the hydraulic oil tank 40A. As a result, the rod 340 of the arm cylinder 34 contracts, and the arm 33 rotates downward with respect to the boom 31 (dump operation).

[0044] The neutral position 440 cuts off the connection between the main pump 41 and the arm cylinder 34 and the connection between the arm cylinder 34 and the hydraulic oil tank 40A, respectively. Therefore, when the arm control valve 44 is switched to the neutral position 440, the inflow and outflow of the hydraulic oil in the arm cylinder 34 stop. As a result, the telescopic movement of the rod 340 of the arm cylinder 34 stops, and the vertical rotation movement of the arm 33 relative to the boom 31 also stops.

[0045] The arm control valve 44 is provided with a pair of pilot oil chambers 44A and 44B to which pilot pressure oil is supplied, similar to the boom control valve 43. The switching between the first switching position 441, the second switching position 442, and the neutral position 440 in the arm control valve 44 is performed by the stroke of the internal spool according to the pressure (pilot pressure) of the pilot pressure oil supplied to the pair of pilot oil chambers 44A and 44B.

[0046] The bucket control valve 45 is provided between the main pump 41 and the bucket cylinder 36, and controls the direction and flow rate of the hydraulic oil led from the main pump 41 to the bucket cylinder 36. The bucket control valve 45 has three switching positions, namely, a first switching position 451, a second switching position 452, and a neutral position 450, similar to the boom control valve 43 and the arm control valve 44.

[0047] The first switching position 451 connects the main pump 41 and the bottom chamber 361 of the bucket cylinder 36, and connects the rod chamber 362 of the bucket cylinder 36 and the hydraulic oil tank 40A. Therefore, when the bucket control valve 45 is switched to the first switching position 451, the hydraulic oil discharged from the main pump 41 flows into the bottom chamber 361 of the bucket cylinder 36, and the hydraulic oil in the rod chamber 362 of the bucket cylinder 36 is discharged to the hydraulic oil tank 40A. As a result, the rod 360 of the bucket cylinder 36 extends, and the bucket 35 rotates upward relative to the arm 33 (crowd operation).

[0048] The second switching position 452 connects the main pump 41 to the rod chamber 362 of the bucket cylinder 36 and connects the bottom chamber 361 of the bucket cylinder 36 to the hydraulic oil tank 40A. Therefore, when the bucket control valve 45 switches to the second switching position 452, the hydraulic oil discharged from the main pump 41 flows into the rod chamber 362 of the bucket cylinder 36, and the hydraulic oil in the bottom chamber 361 of the bucket cylinder 36 is discharged to the hydraulic oil tank 40A. As a result, the rod 360 of the bucket cylinder 36 contracts, and the bucket 35 rotates downward with respect to the arm 33 (dumping operation).

[0049] The neutral position 450 cuts off the connection between the main pump 41 and the bucket cylinder 36 and the connection between the bucket cylinder 36 and the hydraulic oil tank 40A, respectively. Therefore, when the bucket control valve 45 switches to the neutral position 450, the inflow and outflow of the hydraulic oil in the bucket cylinder 36 stop. As a result, the expansion and contraction operation of the rod 360 of the bucket cylinder 36 stops, and the vertical rotation operation of the bucket 35 with respect to the arm 33 also stops.

[0050] Similar to the boom control valve 43 and the arm control valve 44, the bucket control valve 45 is provided with a pair of pilot oil chambers 45A and 45B to which pilot pressure oil is supplied. The switching between the first switching position 451, the second switching position 452, and the neutral position 450 in the bucket control valve 45 is performed by the internal spool stroking according to the pressure (pilot pressure) of the pilot pressure oil supplied to the pair of pilot oil chambers 45A and 45B.

[0051] The boom pilot pressure generating device 46 generates a pilot pressure corresponding to the operation direction and operation amount of the first operation lever 221 for operating the boom 31 from the pilot pressure oil led from the pilot pump 42. The boom pilot pressure generating device 46 and a pair of pilot oil chambers 43A and 43B of the boom control valve 43 are connected by a pair of pilot pipelines 401A and 401B. The pilot pressure generated by the boom pilot pressure generating device 46 acts on the pair of pilot oil chambers 43A and 43B via the pair of pilot pipelines 401A and 401B.

[0052] The arm pilot pressure generating device 47 generates a pilot pressure corresponding to the operation direction and operation amount of the second operation lever 222 for operating the arm 33 from the pilot pressure oil led from the pilot pump 42. The arm pilot pressure generating device 47 and a pair of pilot oil chambers 44A and 44B of the arm control valve 44 are connected by a pair of pilot pipelines 402A and 402B. The pilot pressure generated by the arm pilot pressure generating device 47 acts on the pair of pilot oil chambers 44A and 44B via the pair of pilot pipelines 402A and 402B.

[0053] The bucket pilot pressure generating device 48 generates a pilot pressure corresponding to the operation direction and operation amount of the first operation lever 221 for operating the bucket 35 from the pilot pressure oil led from the pilot pump 42. The bucket pilot pressure generating device 48 and a pair of pilot oil chambers 45A and 45B of the bucket control valve 45 are connected by a pair of pilot pipelines 403A and 403B. The pilot pressure generated by the bucket pilot pressure generating device 48 acts on the pair of pilot oil chambers 45A and 45B via the pair of pilot pipelines 403A and 403B.

[0054] Both the first operation lever 221 and the second operation lever 222 for operating the working device 13 are provided in the driver's cab 22 (see FIG. 1). In this embodiment, the operation of the boom 31 and the operation of the bucket 35 are performed by the same first operation lever 221.

[0055] In the following description, the "boom pilot pressure generating device 46, the arm pilot pressure generating device 47, and the bucket pilot pressure generating device 48" may be simply referred to as "each pilot pressure generating device 46 to 48".

[0056] The gate lock valve 49 is a safety valve provided between the pilot pump 42 and each of the pilot pressure generating devices 46 to 48, and has a connection position 49A for connecting the pilot pump 42 and each of the pilot pressure generating devices 46 to 48, and a cutoff position 49B for cutting off the connection between the pilot pump 42 and each of the pilot pressure generating devices 46 to 48.

[0057] In this embodiment, the gate lock valve 49 is an electromagnetic switching valve, and the switching between the connection position 49A and the cutoff position 49B is controlled by the controller 5. The gate lock valve 49 is held at the cutoff position 49B by the biasing force of a spring when de-energized, and switches from the cutoff position 49B to the connection position 49A against the biasing force of the spring when a switching signal (switching command current) is output from the controller 5.

[0058] When the gate lock lever 223 provided in the operator's cab 22 is operated to the unlock position, the controller 5 outputs a switching signal for instructing switching to the connection position 49A to the gate lock valve 49. The operation of the gate lock lever 223 to the unlock position is detected by a position sensor (not shown) attached to the gate lock lever 223.

[0059] The machine control valve unit 6 is a device for realizing a machine control function that automatically operates the working device 13 along a target construction surface by the controller 5 regardless of the operations of the first operation lever 221 and the second operation lever 222 by the operator.

[0060] As shown in FIGS. 2 and 3, the valve unit 6 for machine control is provided on a pair of pilot pipelines 401A, 401B, 402A, 402B, 403A, 403B, and includes eight first to eighth electromagnetic proportional valves 61A, 61B, 62A, 62B, 63A, 63B, 63C, 63D and three first to third shuttle valves 601, 602, 603. The first to eighth electromagnetic proportional valves 61A, 61B, 62A, 62B, 63A, 63B, 63C, 63D are each controlled by the controller 5.

[0061] The first electromagnetic proportional valve 61A has its primary port side connected to the pilot pump 42 via the gate lock valve 49, and reduces and outputs the pilot pressure from the pilot pump 42 according to the command signal output from the controller 5.

[0062] The first shuttle valve 601 is connected to one pilot pipeline 401A that connects the boom pilot pressure generating device 46 and one pilot oil chamber 43A of the boom control valve 43 and to the secondary port side of the first electromagnetic proportional valve 61A, and selects the higher pressure side among the pilot pressure in the one pilot pipeline 401A and the control pressure output from the first electromagnetic proportional valve 61A, and outputs it to one pilot oil chamber 43A of the boom control valve 43.

[0063] The second electromagnetic proportional valve 61B is provided on the other pilot pipeline 401B that connects the boom pilot pressure generating device 46 and the other pilot oil chamber 43B of the boom control valve 43, and reduces the pilot pressure in the other pilot pipeline 401B according to the command signal output from the controller 5 and outputs it to the other pilot oil chamber 43B of the boom control valve 43.

[0064] The third electromagnetic proportional valve 62A is provided on one pilot pipeline 402A that connects the arm pilot pressure generating device 47 and one pilot oil chamber 44A of the arm control valve 44, and reduces the pilot pressure in the one pilot pipeline 402A according to the command signal output from the controller 5 and outputs it to one pilot oil chamber 44A of the arm control valve 44.

[0065] The fourth electromagnetic proportional valve 62B is provided on the other pilot pipeline 402B that connects the arm pilot pressure generating device 47 and the other pilot oil chamber 44B of the arm control valve 44, and reduces the pilot pressure in the other pilot pipeline 402B according to the command signal output from the controller 5 and outputs it to the other pilot oil chamber 44B of the arm control valve 44.

[0066] The fifth electromagnetic proportional valve 63A is provided on one pilot pipeline 403A that connects the bucket pilot pressure generating device 48 and one pilot oil chamber 45A of the bucket control valve 45, and reduces the pilot pressure in the one pilot pipeline 403A according to the command signal output from the controller 5 and outputs it.

[0067] The sixth electromagnetic proportional valve 63C has its primary port side connected to the pilot pump 42 via the gate lock valve 49, and reduces the pilot pressure from the pilot pump 42 according to the command signal output from the controller 5 and outputs it.

[0068] The second shuttle valve 602 is connected to the secondary port side of the fifth electromagnetic proportional valve 63A and the secondary port side of the sixth electromagnetic proportional valve 63C, selects the high-pressure side among the control pressures output from the fifth electromagnetic proportional valve 63A and the control pressures output from the sixth electromagnetic proportional valve 63C, and outputs it to one pilot oil chamber 45A of the bucket control valve 45.

[0069] The seventh electromagnetic proportional valve 63B is provided on the other pilot pipeline 403B that connects the bucket pilot pressure generating device 48 and the other pilot oil chamber 45B of the bucket control valve 45, and reduces the pilot pressure in the other pilot pipeline 403B according to the command signal output from the controller 5 and outputs it.

[0070] The eighth electromagnetic proportional valve 63D has its primary port side connected to the pilot pump 42 via the gate lock valve 49, and reduces the pilot pressure from the pilot pump 42 according to the command signal output from the controller 5 and outputs it.

[0071] The third shuttle valve 603 is connected to the secondary port side of the seventh electromagnetic proportional valve 63B and the secondary port side of the eighth electromagnetic proportional valve 63D, selects the high-pressure side among the control pressures output from the seventh electromagnetic proportional valve 63B and the control pressure output from the eighth electromagnetic proportional valve 63D, and outputs it to the other pilot oil chamber 45B of the bucket control valve 45.

[0072] Also, pressure sensors 60A to 60F for detecting the pilot pressures generated by the respective pilot pressure generating devices 46 to 48 and outputting them to the controller 5 are provided on each of the pair of pilot pipelines 401A, 401B, 402A, 402B, 403A, 403B. In FIG. 3, the electrical connection lines connecting the pressure sensors 60A to 60F and the controller 5 are omitted.

[0073] The second electromagnetic proportional valve 61B, the third electromagnetic proportional valve 62A, the fourth electromagnetic proportional valve 62B, the fifth electromagnetic proportional valve 63A, and the seventh electromagnetic proportional valve 63B are each held in a state where the opening degree is maximum (fully open state) by the biasing force of the spring when not energized, and when a command current (command signal) is output from the controller 5, the opening degree becomes smaller against the biasing force of the spring as the magnitude of the command current value increases.

[0074] The first electromagnetic proportional valve 61A, the sixth electromagnetic proportional valve 63C, and the eighth electromagnetic proportional valve 63D are each held in a state where the opening degree is zero (fully closed state) by the biasing force of the spring when not energized, and when a command current (command signal) is output from the controller 5, the opening degree becomes larger against the biasing force of the spring as the magnitude of the command current value increases.

[0075] In such a valve unit 6 for machine control, when a command signal is output from the controller 5 and the first electromagnetic proportional valve 61A, the sixth electromagnetic proportional valve 63C, and the eighth electromagnetic proportional valve 63D are driven, if the pilot pressure is not generated by the boom pilot pressure generating device 46 and the bucket pilot pressure generating device 48, that is, even when the operator does not operate the first operation lever 221, the pilot pressure can be generated based on the pilot pressure oil from the pilot pump 42. Thereby, even without the operation by the operator, it becomes possible to forcibly perform the raising operation of the boom 31, the crowd operation of the bucket 35, and the dump operation of the bucket 35 by the control of the controller 5.

[0076] Also, in the valve unit 6 for machine control, when a command signal is output from the controller 5 and the second electromagnetic proportional valve 61B, the third electromagnetic proportional valve 62A, the fourth electromagnetic proportional valve 62B, the fifth electromagnetic proportional valve 63A, and the seventh electromagnetic proportional valve 63B are driven, it is possible to generate a pilot pressure obtained by reducing the pilot pressure generated by each of the pilot pressure generating devices 46 to 48. Thereby, it becomes possible to forcibly reduce the lowering operation speed of the boom 31, the crowd operation speed and the dump operation speed of the arm 33, and the crowd operation speed and the dump operation speed of the bucket 35 from the operation amount of the operator.

[0077] Here, among the pilot signals (pilot pressures) acting on the pair of pilot oil chambers 43A, 43B, 44A, 44B, 45A, 45B of the control valves 43 to 45, the pilot signal generated by each of the pilot pressure generating devices 46 to 48 by the operation of the operator is defined as the "first pilot signal".

[0078] Of the pilot signals acting on the pair of pilot oil chambers 43A, 43B, 44A, 44B, 45A, and 45B of the respective control valves 43 to 45, the controller 5 drives the second electromagnetic proportional valve 61B, the third electromagnetic proportional valve 62A, the fourth electromagnetic proportional valve 62B, the fifth electromagnetic proportional valve 63A, and the seventh electromagnetic proportional valve 63B to correct (reduce the pressure) the first pilot signal to generate a pilot signal, and the controller 5 drives the first electromagnetic proportional valve 61A, the sixth electromagnetic proportional valve 63C, and the eighth electromagnetic proportional valve 63D to generate a pilot signal newly generated separately from the first pilot signal. These are combined to form the "second pilot signal".

[0079] The second pilot signal is generated when the speed of the control point of the working device 13 generated by the first pilot signal does not satisfy a predetermined condition, and is generated as a signal for generating the speed of the control point of the working device 13 that satisfies the predetermined condition.

[0080] For example, when a first pilot signal is output to one pilot oil chamber 43A of the boom control valve 43 and a second pilot signal is output to the other pilot oil chamber 43B, the second pilot signal is given priority, the first pilot signal is blocked by the second electromagnetic proportional valve 61B, and the second pilot signal is input to the other pilot oil chamber 43B. The same applies to the arm control valve 44 and the bucket control valve 45.

[0081] Therefore, among the boom control valve 43, the arm control valve 44, and the bucket control valve 45, those for which the second pilot signal is generated are controlled based on the second pilot signal, and those for which the second pilot signal is not generated are controlled based on the first pilot signal. Also, among the boom control valve 43, the arm control valve 44, and the bucket control valve 45, those for which neither the first pilot signal nor the second pilot signal is generated are not driven because they are not controlled by the pilot signal.

[0082] Therefore, the operation control of the working device 13 by the machine control function corresponds to the control of the boom control valve 43, the arm control valve 44, and the bucket control valve 45 based on the second pilot signal.

[0083] Also, a shuttle block 404 is provided on the downstream side of the machine control valve unit 6, and the first pilot signal or the second pilot signal is input to the regulator 410 of the main pump 41 via this shuttle block 404. The regulator 410 controls the discharge flow rate of the main pump 41 based on the input first pilot signal or second pilot signal.

[0084] In the present embodiment, as shown in FIG. 2, a direction switching valve 70 is provided between the pilot pump 42 and the gate lock valve 49. Specifically, the direction switching valve 70 has its primary port side connected to the discharge pipeline 700 of the pilot pump 42, and its secondary port side connected to the gate lock valve 49 via any one of the first to third pipelines 701 to 703.

[0085] The first pipeline 701 is a warm-up pipeline that warms the pilot pressure oil discharged from the pilot pump 42. In the present embodiment, a throttle 71 for restricting the flow rate of the pilot pressure oil to warm the pilot pressure oil is provided in the first pipeline 701. The pilot pressure oil guided to the first pipeline 701 is warmed by the throttle 71 and then guided to a pair of pilot oil chambers 43A, 43B, 44A, 44B, 45A, 45B of the control valves 43 to 45 via the gate lock valve 49.

[0086] Note that as a method for warming the pilot pressure oil, it is not necessarily required to flow the pilot pressure oil through the throttle 71. For example, a method using the exhaust heat of the engine 40 may be used. In this case, a fan for cooling the exhaust heat of the engine 40 is placed over the first pipeline 701, and the exhaust heat of the engine 40 is radiated toward the first pipeline 701 by the wind of the fan, thereby warming the pilot pressure oil flowing in the first pipeline 701.

[0087] The second pipeline 702 is a cooling pipeline that cools the pilot pressure oil discharged from the pilot pump 42. In this embodiment, a cooling fan 72 that generates cooling air is installed in the second pipeline 702. The cooling fan 72 is controlled by the controller 5. The pilot pressure oil led to the second pipeline 702 is cooled by the cooling fan 72 and then led to a pair of pilot oil chambers 43A, 43B, 44A, 44B, 45A, 45B of each control valve 43-45 via the gate lock valve 49.

[0088] Note that, as a method for cooling the pilot pressure oil, it is not necessarily required to generate cooling air with the cooling fan 72. For example, the pilot pressure oil may be cooled by exposing the second pipeline 702 to the outside air, such as by removing the body cover.

[0089] Unlike the first pipeline 701 and the second pipeline 702, the third pipeline 703 is composed only of piping and is a pipeline that leads the pilot pressure oil discharged from the pilot pump 42 to the gate lock valve 49 without temperature adjustment.

[0090] The direction switching valve 70 includes a warm-up position 70A that connects the discharge pipeline 700 and the first pipeline 701, a cooling position 70B that connects the discharge pipeline 700 and the second pipeline 702, and a neutral position 70C that connects the discharge pipeline 700 and the third pipeline 703.

[0091] Further, the direction switching valve 70 is an electromagnetic switching valve, and the warm-up position 70A, the cooling position 70B, and the neutral position 70C are switched based on a command signal output from the controller 5. The controller 5 controls the switching position of the direction switching valve 70 based on the temperature of the pressure oil in the main circuit (main circuit oil temperature), that is, the temperature Tm of the hydraulic oil discharged from the main pump 41 (hereinafter referred to as "operating oil temperature Tm"), and the temperature of the pressure oil in the pilot circuit (pilot circuit oil temperature), that is, the temperature Tp of the pilot pressure oil led to each pilot pressure generating device 46-48 (hereinafter referred to as "pilot oil temperature Tp").

[0092] The operating oil temperature Tm is detected by a first temperature sensor 81 provided on the discharge side of the main pump 41, and the pilot oil temperature Tp is detected by a second temperature sensor 82 provided on the downstream side of the gate lock valve 49 and upstream of each pilot pressure generating device 46 to 48, respectively.

[0093] When the pilot oil temperature Tp detected by the second temperature sensor 82 is lower than the operating oil temperature Tm detected by the first temperature sensor 81 (Tp < Tm), the controller 5 commands the directional control valve 70 to switch to the warm-up position 70A. On the other hand, when the pilot oil temperature Tp detected by the second temperature sensor 82 is higher than the operating oil temperature Tm detected by the first temperature sensor 81 (Tp > Tm), the controller 5 commands the directional control valve 70 to switch to the cooling position 70B and commands the cooling fan 72 to start.

[0094] Furthermore, in the present embodiment, the controller 5 compares the magnitude relationship between the difference (absolute value of the difference) between the operating oil temperature Tm detected by the first temperature sensor 81 and the pilot oil temperature Tp detected by the second temperature sensor 82 and a predetermined threshold value α in addition to the magnitude relationship between them, thereby determining whether or not to switch to the neutral position 70C. The predetermined threshold value α is input to the controller 5 by the input terminal 224. However, the predetermined threshold value α does not necessarily have to be set using the input terminal 224 and may be stored in the controller 5 in advance.

[0095] A monitor 225 connected to the controller 5 is installed in the cab 22, and the control content by the controller 5, specifically, the operating state of the engine 40, the control state of the gate lock valve 49, the ON / OFF state of the machine control function, and the switching state of the directional control valve 70 are displayed.

[0096] (Functional Configuration of Controller 5) Next, the specific functional configuration of the controller 5 will be described with reference to FIG. 4.

[0097] FIG. 4 is a functional block diagram showing the functions of the controller 5 according to the first embodiment.

[0098] The controller 5 is configured such that a CPU, a RAM, a ROM, an input I / F, and an output I / F are connected to each other via a bus. Then, operating devices such as a key switch 220, a gate lock lever 223, and an input terminal 224, and various sensors such as a first temperature sensor 81 and a second temperature sensor are connected to the input I / F, and a direction changeover valve 70, a monitor 225, etc. are connected to the output I / F.

[0099] In such a hardware configuration, the CPU reads out a control program (software) stored in a recording medium such as a ROM or an optical disk and expands it on the RAM, and by executing the expanded control program, the control program and the hardware cooperate to realize the functions of the controller 5.

[0100] In this embodiment, the controller 5 is described as a computer configured by a combination of software and hardware. However, it is not limited to this. For example, as an example of the configuration of other computers, an integrated circuit that realizes the functions of the control program executed on the side of the hydraulic excavator 1 may be used.

[0101] The controller 5 includes a data acquisition unit 51, an engine start determination unit 52, a gate lock valve state determination unit 53, an oil temperature calculation unit 54, an oil temperature determination unit 55, a storage unit 56, a valve command unit 57, and a monitor command unit 58.

[0102] The data acquisition unit 51 acquires an operation signal output from the key switch 220, a position signal output from the gate lock lever 223 (position sensor), the operating oil temperature Tm detected by the first temperature sensor 81, the pilot oil temperature Tp detected by the second temperature sensor 82, and data regarding a predetermined threshold value α input at the input terminal 224, respectively.

[0103] The engine start determination unit 52 determines whether the engine 40 has started based on the operation signal from the key switch 220 acquired by the data acquisition unit 51. Specifically, when the start signal is acquired by the data acquisition unit 51, the engine start determination unit 52 determines that the engine 40 has started. On the other hand, when the stop signal is acquired by the data acquisition unit 51, the engine start determination unit 52 determines that the engine 40 has stopped.

[0104] In addition, when the start signal is acquired by the data acquisition unit 51, the controller 5 outputs a control signal related to starting to the engine 40 and the engine start determination unit 52 determines that the engine 40 is in a starting state. Similarly, when the stop signal is acquired by the data acquisition unit 51, the controller 5 outputs a control signal related to stopping to the engine 40 and the engine start determination unit 52 determines that the engine 40 is in a stopped state.

[0105] The gate lock valve state determination unit 53 determines the state of the gate lock valve 49 based on the position signal from the gate lock lever 223 acquired by the data acquisition unit 51. Specifically, when the position signal related to the unlocked position is acquired by the data acquisition unit 51, the gate lock valve state determination unit 53 determines that the gate lock valve 49 is in an open state. On the other hand, when the position signal from the gate lock lever 223 is not acquired by the data acquisition unit 51, the gate lock valve state determination unit 53 determines that the gate lock valve 49 is in a closed state.

[0106] In addition, when the position signal related to the unlocked position is acquired by the data acquisition unit 51, the controller 5 outputs a switching signal for instructing the switching of the gate lock valve 49 to the connection position 49A and the gate lock valve state determination unit 53 determines that the gate lock valve 49 is in an open state.

[0107] The oil temperature calculation unit 54 calculates the difference |Tm - Tp| between the operating oil temperature Tm and the pilot oil temperature Tp acquired by the data acquisition unit 51.

[0108] The oil temperature determination unit 55 compares the magnitudes of the operating oil temperature Tm and the pilot oil temperature Tp acquired by the data acquisition unit 51. Further, the oil temperature determination unit 55 determines whether or not the pilot oil temperature Tp acquired by the data acquisition unit 51 is equal to or higher than the minimum recommended temperature Tth. This "minimum recommended temperature Tth" corresponds to the pilot oil temperature at which the responsiveness of each control valve 43 to 45 can be ensured at a minimum, and is stored in the storage unit 56.

[0109] Furthermore, in the present embodiment, the oil temperature determination unit 55 determines whether or not the difference |Tm - Tp| between the operating oil temperature Tm and the pilot oil temperature Tp calculated by the oil temperature calculation unit 54 is equal to or less than a predetermined threshold value α. This "predetermined threshold value α" is a value arbitrarily set by the input terminal 224 according to the external environment such as the environment at the site where the hydraulic excavator 1 is used, and is acquired by the data acquisition unit 51 and stored in the storage unit 56.

[0110] The valve command unit 57 outputs a switching command signal to the direction switching valve 70 according to the determination result in the oil temperature determination unit 55. Specifically, when it is determined in the oil temperature determination unit 55 that the pilot oil temperature Tp is less than the minimum recommended temperature Tth (Tp < Tth), the valve command unit 57 outputs a first switching command signal for instructing the direction switching valve 70 to switch to the warm-up position 70A.

[0111] Thereby, the direction switching valve 70 switches to the warm-up position 70A, and the pilot pressure oil discharged from the pilot pump 42 is guided to the gate lock valve 49 after being heated via the first pipeline 701.

[0112] In addition, when it is determined in the oil temperature determination unit 55 that the pilot oil temperature Tp is lower than the operating oil temperature Tm (Tp < Tm) and the difference (Tm - Tp) between the operating oil temperature Tm and the pilot oil temperature Tp is larger than the predetermined threshold value α (Tm - Tp > α), the valve command unit 57 also outputs a first switching command signal to the direction switching valve 70.

[0113] Even in this case, the direction switching valve 70 switches to the warm-up position 70A, and the pilot pressure oil discharged from the pilot pump 42 is guided to the gate lock valve 49 after being heated through the first pipeline 701.

[0114] On the other hand, when the valve command unit 57 determines in the oil temperature determination unit 55 that the pilot oil temperature Tp is equal to or higher than the operating oil temperature Tm (Tp ≧ Tm), and the difference (Tp - Tm) between the pilot oil temperature Tp and the operating oil temperature Tm is greater than a predetermined threshold value α (Tp - Tm > α), the valve command unit 57 outputs a second switching command signal for commanding the direction switching valve 70 to switch to the cooling position 70B.

[0115] As a result, the direction switching valve 70 switches to the cooling position 70B, and the pilot pressure oil discharged from the pilot pump 42 is guided to the gate lock valve 49 after being cooled through the second pipeline 702.

[0116] In addition, even when the valve command unit 57 determines in the oil temperature determination unit 55 that the pilot oil temperature Tp is lower than the operating oil temperature Tm (Tp < Tm), or the pilot oil temperature Tp is equal to or higher than the operating oil temperature Tm (Tp ≧ Tm), but the difference (|Tp - Tm|) between the operating oil temperature Tm and the pilot oil temperature Tp is equal to or less than a predetermined threshold value α (|Tm - Tp| ≦ α), the valve command unit 57 outputs a third switching command signal for commanding the direction switching valve 70 to switch to the neutral position 70N.

[0117] As a result, the direction switching valve 70 switches to the neutral position 70N, and the pilot pressure oil discharged from the pilot pump 42 is guided to the gate lock valve 49 through the third pipeline 703.

[0118] The monitor command unit 58 outputs a warm-up display signal for displaying the implementation of warm-up of the pilot pressure oil or a cooling display signal for displaying the implementation of cooling of the pilot pressure oil to the monitor 225 according to the determination result in the oil temperature determination unit 55. As a result, when the warm-up display signal is input, the monitor 225 displays that the warm-up of the pilot pressure oil is implemented, and when the cooling display signal is input, the monitor 225 displays that the cooling of the pilot pressure oil is implemented.

[0119] (Processing in Controller 5) Next, the specific processing flow executed in the controller 5 will be described with reference to FIG. 5.

[0120] FIG. 5 is a flowchart showing the processing flow executed by the controller 5 according to the first embodiment.

[0121] In the controller 5, first, the engine start determination unit 52 determines whether the engine 40 has started based on the operation signal (start signal or stop signal) from the key switch 220 acquired by the data acquisition unit 51 (step S501).

[0122] If it is determined in step S501 that the engine 40 has started (step S501 / YES), the gate lock valve state determination unit 53 determines whether a position signal (position signal related to the unlocked position) from the gate lock lever 223 has been acquired by the data acquisition unit 51, that is, whether the gate lock valve 49 is in the open state (step S502).

[0123] If it is determined in step S502 that the gate lock valve 49 is in the open state (step S502 / YES), the data acquisition unit 51 acquires the operating oil temperature Tm output from the first temperature sensor 81, the pilot oil temperature Tp output from the second temperature sensor 82, and a predetermined threshold value α output from the input terminal 224, respectively (step S503).

[0124] Next, the oil temperature calculation unit 54 calculates the difference |Tm - Tp| between the operating oil temperature Tm and the pilot oil temperature Tp acquired in step S503 (step S504). Subsequently, the oil temperature determination unit 55 determines whether the pilot oil temperature Tp acquired in step S503 is equal to or higher than the minimum recommended temperature Tth (step S505).

[0125] If it is determined in step S505 that the pilot oil temperature Tp is equal to or higher than the minimum recommended temperature Tth (Tp ≥ Tth) (step S505 / YES), then, subsequently, the oil temperature determination unit 55 determines whether the pilot oil temperature Tp is lower than the operating oil temperature Tm (step S506).

[0126] If it is determined in step S506 that the pilot oil temperature Tp is lower than the operating oil temperature Tm (Tp < Tm) (step S506 / YES), then, subsequently, the oil temperature determination unit 55 determines whether the difference (Tm - Tp) between the operating oil temperature Tm and the pilot oil temperature Tp is equal to or less than a predetermined threshold α (step S507).

[0127] If it is determined in step S507 that the difference (Tm - Tp) between the operating oil temperature Tm and the pilot oil temperature Tp is equal to or less than the predetermined threshold α (Tm - Tp ≤ α) (step S507 / YES), the valve command unit 57 outputs a third switching command signal to the direction switching valve 70 (step S508), and the processing in the controller 5 ends.

[0128] On the other hand, if it is determined in step S505 that the pilot oil temperature Tp is lower than the minimum recommended temperature Tth (Tp < Tth) (step S505 / NO), the monitor command unit 58 outputs a warm-up display signal to the monitor 225 (step S509). Subsequently, the valve command unit 57 outputs a first switching command signal to the direction switching valve 70 (step S510), and the processing in the controller 5 ends.

[0129] Also, if it is determined in step S506 that the pilot oil temperature Tp is equal to or higher than the operating oil temperature Tm (Tp ≥ Tm) (step S506 / NO), the oil temperature determination unit 55 further determines whether the difference (Tp - Tm) between the pilot oil temperature Tp and the operating oil temperature Tm is equal to or less than the predetermined threshold α (step S511).

[0130] When it is determined in step S511 that the difference (Tp - Tm) between the pilot oil temperature Tp and the operating oil temperature Tm is less than or equal to a predetermined threshold value α (Tp - Tm ≤ α) (step S511 / YES), the process proceeds to step S508, and the valve command unit 57 outputs a third switching command signal to the direction switching valve 70.

[0131] On the other hand, when it is determined in step S511 that the difference (Tp - Tm) between the pilot oil temperature Tp and the operating oil temperature Tm is greater than the predetermined threshold value α (Tp - Tm > α) (step S511 / NO), the monitor command unit 58 outputs a cooling display signal to the monitor 225 (step S512). Subsequently, the valve command unit 57 outputs a second switching command signal to the direction switching valve 70 (step S513), and the processing in the controller 5 ends.

[0132] Although omitted in the flowchart shown in FIG. 5, the controller 5 outputs a command signal related to starting to the cooling fan 72 in step S513.

[0133] Also, when it is determined in step S507 that the difference (Tm - Tp) between the operating oil temperature Tm and the pilot oil temperature Tp is greater than the predetermined threshold value α (Tm - Tp > α) (step S507 / NO), the monitor command unit 58 outputs a warm-up display signal to the monitor 225 (step S514). Then, the valve command unit 57 outputs a first switching command signal to the direction switching valve 70 (step S515), and the processing in the controller 5 ends.

[0134] Also, when it is determined in step S501 that the engine 40 is not started, that is, stopped (step S501 / NO) and when it is determined in step S502 that the gate lock valve 49 is not in the open state, that is, in the closed state (step S502 / NO), the processing in the controller 5 ends in both cases.

[0135] Note that in FIG. 5, the valve command unit 57 outputs each switching command signal to the direction switching valve 70 after the processing (steps S509, S512, and S514) by the monitor command unit 58 (steps S510, S513, and S515). However, the controller 5 does not necessarily have to execute the processing (steps S510, S513, and S515) by the valve command unit 57 after the processing (steps S509, S512, and S514) by the monitor command unit 58, and the processing by the monitor command unit 58 and the processing by the valve command unit 57 may be executed simultaneously.

[0136] As described above, when the pilot oil temperature Tp is lower than the operating oil temperature Tm (Tp < Tm), the pilot pressure oil discharged from the pilot pump 42 is heated in the first pipeline 701. On the other hand, when the pilot oil temperature Tp is higher than the operating oil temperature Tm (Tp > Tm), the pilot pressure oil discharged from the pilot pump 42 is cooled in the second pipeline 702, thereby suppressing the deviation between the pilot oil temperature Tp and the operating oil temperature Tm. Therefore, the working device 13 can perform an operation following an operation command by the operator or an operation command by machine control.

[0137] In particular, the pilot pressure oil discharged from the pilot pump 42 has a lower output than the hydraulic oil discharged from the main pump 41 and has a property of being difficult to heat up because the heat generated by pipes, valves, etc. is small. Also, in the case of the hydraulic excavator 1 equipped with a machine control function as in this embodiment, if the working device 13 is not frequently operated in the machine control mode, the pilot pressure oil on the pilot valve unit 6 side for machine control will cool down, and it is necessary to adjust (warm up) the pilot oil temperature every time the machine control mode is switched.

[0138] Thus, even when a deviation is likely to occur between the pilot oil temperature Tp and the operating oil temperature Tm, the operating oil temperature Tm can be monitored by the first temperature sensor 81, and the pilot oil temperature Tp can be monitored by the second temperature sensor 82, and since it is possible to pre-warm the pilot pressure oil, the working device 13 can be operated as per the operation command without reducing the working efficiency.

[0139] Furthermore, in the present embodiment, the direction switching valve 70 is switched to the warm-up position 70A or the cooling position 70B only when the difference |Tm - Tp| between the operating oil temperature Tm and the pilot oil temperature Tp is greater than a predetermined threshold α (|Tm - Tp| > α), and when the difference |Tm - Tp| between the operating oil temperature Tm and the pilot oil temperature Tp is less than or equal to the predetermined threshold α (|Tm - Tp| ≤ α), the direction switching valve 70 is set to the neutral position 70N. Therefore, compared with the case where the direction switching valve 70 is switched based only on the magnitude relationship between the operating oil temperature Tm and the pilot oil temperature Tp, the number of switching operations of the direction switching valve 70 can be reduced. Thereby, it becomes possible to suppress excessive operations of each component constituting the hydraulic drive system 4 and extend the life of each component.

[0140] <Second Embodiment> Next, the hydraulic drive system 4 according to the second embodiment of the present invention will be described with reference to FIGS. 6 and 7. Note that the same reference numerals are given to the components common to those described for the hydraulic drive system 4 according to the first embodiment, and the description thereof is omitted. The same applies to the third and fourth embodiments described later.

[0141] FIG. 6 is a functional block diagram showing the functions of the controller 5A according to the second embodiment of the present invention. FIG. 7 is a flowchart showing the flow of processing executed by the controller 5A according to the second embodiment.

[0142] The hydraulic excavator 1 according to this embodiment is provided with a mode selection button 226 as a mode selection device for selecting a warm-up mode for heating pilot pressure oil and a cooling mode for cooling pilot pressure oil in the operator's cab 22. The mode selection button 226 outputs a mode signal (warm-up mode signal or cooling mode signal) selected by the operator to the controller 5A.

[0143] As shown in FIG. 6, the controller 5A includes a data acquisition unit 51A, an engine start determination unit 52, a gate lock valve state determination unit 53, an oil temperature calculation unit 54, an oil temperature determination unit 55, a storage unit 56, a valve command unit 57A, a monitor command unit 58, and in addition, a mode determination unit 59.

[0144] The data acquisition unit 51A acquires the operating oil temperature Tm detected by the first temperature sensor 81, the pilot oil temperature Tp detected by the second temperature sensor 82, data regarding a predetermined threshold value α input at the input terminal 224, and in addition to the operation signal from the key switch 220 and the position signal from the gate lock lever 223, the mode signal from the mode selection button 226.

[0145] The mode determination unit 59 determines the mode selected by the mode selection button 226 based on the mode signal acquired by the data acquisition unit 51A. Specifically, when the warm-up mode signal is acquired by the data acquisition unit 51A, the mode determination unit 59 determines that the warm-up mode is selected by the mode selection button 226, and when the cooling mode signal is acquired by the data acquisition unit 51A, the mode determination unit 59 determines that the cooling mode is selected by the mode selection button 226.

[0146] The valve command unit 57A outputs a switching command signal to the direction switching valve 70 based on the determination result of the oil temperature determination unit 55 and the determination result of the mode determination unit 59.

[0147] Specifically, when the oil temperature determination unit 55 determines that the pilot oil temperature Tp is less than the minimum recommended temperature Tth (Tp < Tth), and the mode determination unit 59 determines that the warm-up mode is selected, the valve command unit 57A outputs a first switching command signal to the direction switching valve 70.

[0148] Further, when the oil temperature determination unit 55 determines that the pilot oil temperature Tp is equal to or higher than the operating oil temperature Tm (Tp ≥ Tm), the difference (Tp - Tm) between the pilot oil temperature Tp and the operating oil temperature Tm is greater than a predetermined threshold value α (Tp - Tm > α), and the mode determination unit 59 determines that the cooling mode is selected, the valve command unit 57A outputs a second switching command signal to the direction switching valve 70.

[0149] Also, when the oil temperature determination unit 55 determines that the pilot oil temperature Tp is lower than the operating oil temperature Tm (Tp < Tm), the difference (Tm - Tp) between the operating oil temperature Tm and the pilot oil temperature Tp is greater than a predetermined threshold value α (Tm - Tp > α), and the mode determination unit 59 determines that the warm-up mode is selected, the valve command unit 57A outputs a first switching command signal to the direction switching valve 70.

[0150] Therefore, in the present embodiment, when the determination result in the oil temperature determination unit 55 does not correspond to the determination result in the mode determination unit 59, the valve command unit 57A does not output either the first switching command signal or the second switching command signal to the direction switching valve 70.

[0151] As shown in FIG. 7, when the monitor command unit 58 outputs a warm-up display signal to the monitor 225 in step S509, the mode determination unit 59 determines whether the mode signal acquired by the data acquisition unit 51 is a warm-up mode signal, that is, whether the warm-up mode is selected by the mode selection button 226 (step S521).

[0152] If it is determined in step S521 that the warm-up mode is selected (step S521 / YES), the valve command unit 57A outputs a first switching command signal to the direction switching valve 70 (step S522), and the processing in the controller 5A ends. On the other hand, if it is determined in step S521 that the warm-up mode is not selected (step S521 / NO), the processing in the controller 5A ends as it is.

[0153] Also, when the monitor command unit 58 outputs a cooling display signal to the monitor 225 in step S512, the mode determination unit 59 determines whether the mode signal acquired by the data acquisition unit 51 is a cooling mode signal, that is, whether the cooling mode is selected by the mode selection button 226 (step S523).

[0154] If it is determined in step S523 that the cooling mode is selected (step S523 / YES), the valve command unit 57A outputs a second switching command signal to the direction switching valve 70 (step S524), and the processing in the controller 5A ends. On the other hand, if it is determined in step S523 that the cooling mode is not selected (step S523 / NO), the processing in the controller 5A ends as it is.

[0155] Also, similar to step S521, when the monitor command unit 58 outputs a warm-up display signal to the monitor 225 in step S514, the mode determination unit 59 determines whether the warm-up mode is selected by the mode selection button 226 (step S525).

[0156] If it is determined in step S525 that the warm-up mode is selected (step S525 / YES), the valve command unit 57A outputs a first switching command signal to the direction switching valve 70 (step S526), and the processing in the controller 5A ends. On the other hand, if it is determined in step S525 that the warm-up mode is not selected (step S525 / NO), the processing in the controller 5A ends as it is.

[0157] In this embodiment, the same operations and effects as those in the first embodiment can be achieved. Furthermore, in this embodiment, even when there is a divergence between the operating oil temperature Tm and the pilot oil temperature Tp, the operator can arbitrarily select whether to warm or cool the pilot pressure oil.

[0158] <Third Embodiment> Next, the hydraulic drive system 4A according to the third embodiment of the present invention will be described with reference to FIGS. 8 to 10.

[0159] FIG. 8 is a circuit diagram showing a configuration example of the hydraulic drive system 4A according to the third embodiment of the present invention. FIG. 9 is a functional block diagram showing the functions of the controller 5B according to the third embodiment. FIG. 10 is a flowchart showing the flow of processing executed by the controller 5B according to the third embodiment.

[0160] The hydraulic drive system 4A according to this embodiment is different from the hydraulic drive system 4 in terms of the warm-up method of the pilot pressure oil in that the warm-up method of the pilot pressure oil in the hydraulic drive system 4 according to the first embodiment.

[0161] As shown in FIG. 8, a branch pipeline 704A through which a part of the hydraulic oil discharged from the main pump 41 flows, branched from the main pipeline 704 connected to the discharge side of the main pump 41, is connected to the first pipeline 701A which is a warm-up pipeline.

[0162] A merging valve 73 as a merging device for reducing the hydraulic oil from the main pump 41 and merging it into the pilot pressure oil flowing through the first pipeline 701A is provided in the branch pipeline 704A. The merging valve 73 has a merging position 73A for guiding the hydraulic oil from the main pump 41 to the first pipeline 701A and a blocking position 73B for blocking the branch pipeline 704A.

[0163] The confluence valve 73 is an electromagnetic switching valve, and the switching between the confluence position 73A and the cutoff position 73B is controlled by the controller 5B. Specifically, when de-energized, the confluence valve 73 is held at the cutoff position 73B by the biasing force of a spring, and when a confluence command signal is output from the controller 5B, it switches to the confluence position 73A against the biasing force of the spring.

[0164] Also, in this embodiment, the confluence valve 73 also has the function of a pressure reducing valve. When a confluence command signal is output from the controller 5B and it switches to the confluence position 73A, it reduces the pressure of the hydraulic oil from the main pump 41 and then guides it to the first pipeline 701A, where it merges with the pilot pressure oil flowing in the first pipeline 701A.

[0165] Note that the confluence device does not necessarily have to be a switching pressure reducing valve that integrally has an electromagnetic switching function and a pressure reducing function. It may be separately provided with an electromagnetic switching valve whose confluence position and cutoff position are switched under the control of the controller 5B, and a pressure reducing valve that reduces the pressure of the hydraulic oil from the main pump 41.

[0166] Also, a check valve 74 is provided between the branch point and the confluence valve 73 in the branch pipeline 704A to prevent the hydraulic oil guided to the branch pipeline 704A side from flowing into each control valve 43 - 45 side. A relief valve 75 is provided on the downstream side of the confluence valve 73 in the branch pipeline 704A to keep the pressure of the hydraulic oil flowing in the branch pipeline 704A constant.

[0167] Furthermore, a check valve 76 is provided between the connection point of the branch pipeline 704A and the first pipeline 701A and the direction switching valve 70 to prevent the hydraulic oil guided from the branch pipeline 704A from flowing into the direction switching valve 70 side.

[0168] The controller 5B includes a data acquisition unit 51, an engine start determination unit 52, a gate lock valve state determination unit 53, an oil temperature calculation unit 54, an oil temperature determination unit 55, a storage unit 56, a valve command unit 57B, and a monitor command unit 58, similar to the controller 5 according to the first embodiment.

[0169] However, unlike the valve command unit 57 in the first embodiment, the valve command unit 57B outputs a switching command signal to the direction switching valve 70 and also outputs a merging command signal to the merging valve 73.

[0170] Specifically, when the oil temperature determination unit 55 determines that the pilot oil temperature Tp is lower than the minimum recommended temperature Tth (Tp < Tth), and when the oil temperature determination unit 55 determines that the pilot oil temperature Tp is less than the operating oil temperature Tm (Tp < Tm) and the difference (Tm - Tp) between the operating oil temperature Tm and the pilot oil temperature Tp is greater than a predetermined threshold α (Tm - Tp > α), the valve command unit 57B outputs a merging command signal to the merging valve 73, respectively.

[0171] As shown in FIG. 10, when a first switching command signal is output to the direction switching valve 70 in each of steps S510 and S515, the valve command unit 57B outputs a merging command signal to the merging valve 73 (steps S531 and S532), and the processing in the controller 5B ends.

[0172] In the flowchart shown in FIG. 10, the valve command unit 57B outputs a merging command signal to the merging valve 73 after outputting a first switching command signal to the direction switching valve 70 (steps S510 and S515) (steps S531 and S532), but it is not limited to this, and the output of the first switching command signal to the direction switching valve 70 and the output of the merging command signal to the merging valve 73 may be executed simultaneously.

[0173] Also in this embodiment, the same operations and effects as those in the first embodiment can be achieved.

[0174] <Fourth Embodiment> Next, the hydraulic drive system 4A according to the fourth embodiment of the present invention will be described with reference to FIGS. 11 and 12.

[0175] FIG. 11 is a functional block diagram showing the functions of the controller 5C according to the fourth embodiment of the present invention. FIG. 12 is a flowchart showing the flow of processing executed by the controller 5C according to the fourth embodiment.

[0176] The hydraulic drive system 4A according to the present embodiment is a combination of the configuration of the hydraulic drive system 4A according to the third embodiment and the configuration of the hydraulic drive system 4 according to the second embodiment.

[0177] As shown in FIG. 11, the controller 5C according to the present embodiment includes a data acquisition unit 51A, an engine start determination unit 52, a gate lock valve state determination unit 53, an oil temperature calculation unit 54, an oil temperature determination unit 55, a storage unit 56, a mode determination unit 59, a valve command unit 57C, and a monitor command unit 58.

[0178] Based on the determination result in the oil temperature determination unit 55 and the determination result in the mode determination unit 59, the valve command unit 57C outputs a switching command signal to the direction switching valve 70 and outputs a merging command signal to the merging valve 73.

[0179] As shown in FIG. 12, when it is determined that the warm-up mode is selected in step S521 (step S521 / YES), the valve command unit 57C outputs a first switching command signal to the direction switching valve 70 (step S522), and then outputs a merging command signal to the merging valve 73 (step S541), and the processing in the controller 5C ends.

[0180] Similarly, when it is determined that the warm-up mode is selected in step S524 (step S524 / YES), the valve command unit 57C outputs a first switching command signal to the direction switching valve 70 (step S525), and then outputs a merging command signal to the merging valve 73 (step S542), and the processing in the controller 5C ends.

[0181] Also in the present embodiment, the same operations and effects as those in the first embodiment and the second embodiment can be achieved.

[0182] The above describes each embodiment of the present invention. Note that the present invention is not limited to the above-described embodiments and includes various modifications. For example, each of the above-described embodiments has been described in detail for easy understanding of the present invention, and is not necessarily limited to having all the configurations described. Also, a part of the configuration of each embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can also be added to the configuration of each embodiment. Furthermore, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

[0183] For example, in each of the above embodiments, the hydraulic excavator 1 has been described as one aspect of the working machine. However, the present invention is not limited to this, and the present invention can be applied to other working machines as long as they are working machines equipped with the working device 13.

[0184] Also, in each of the above embodiments, the controllers 5, 5A, 5B, 5C output a switching command signal to the direction switching valve 70 after considering the magnitude relationship between the difference |Tm - Tp| between the operating oil temperature Tm and the pilot oil temperature Tp and a predetermined threshold value α. However, it is sufficient to output a switching command signal to the direction switching valve 70 based on at least the magnitude relationship between the operating oil temperature Tm and the pilot oil temperature Tp.

Explanation of Reference Numerals

[0185] 1: Hydraulic excavator (working machine) 5, 5A, 5B, 5C: Controllers 12: Slewing body (machine body) 13: Working device 32: Boom cylinder (hydraulic actuator) 34: Arm cylinder (hydraulic actuator) 36: Bucket cylinder (hydraulic actuator) 41: Main pump 42: Pilot pump 43: Boom control valve (control valve) 44: Arm control valve (control valve) 45: Control valve for bucket (control valve) 70: Direction changeover valve 70A: Warm-up position 70B: Cooling position 70N: Neutral position 71: Throttle 73: Confluence valve (confluence device) 81: First temperature sensor 82: Second temperature sensor 226: Mode selection button (mode selection device) 701: First pipeline (warm-up pipeline) 702: Second pipeline (cooling pipeline) 704: Main pipeline 704A: Branch pipeline

Claims

【Claim 1】 A machine body, A working device attached to the machine body, A hydraulic actuator for driving the working device, A main pump for supplying pressure oil to the hydraulic actuator, A control valve for controlling the flow rate of the pressure oil led from the main pump to the hydraulic actuator, A pilot pump for supplying pilot pressure oil to the pilot oil chamber of the control valve, In a working machine equipped with the above, A first temperature sensor for detecting the main circuit oil temperature in the main circuit equipped with the control valve, A second temperature sensor for detecting the pilot oil temperature which is the temperature of the pilot pressure oil, A first pipeline as a warm-up pipeline for heating the pilot pressure oil discharged from the pilot pump and leading it to the pilot oil chamber, A second pipeline as a cooling pipeline for cooling the pilot pressure oil discharged from the pilot pump and leading it to the pilot oil chamber, A third pipeline for leading the pilot pressure oil discharged from the pilot pump to the pilot oil chamber without temperature adjustment, A direction switching valve for switching the direction of the pilot pressure oil led from the pilot pump to the pilot oil chamber, A controller for controlling the direction switching valve, Having, The direction switching valve, A warm-up position for leading the pilot pressure oil discharged from the pilot pump to the pilot oil chamber via the first pipeline, A cooling position for leading the pilot pressure oil discharged from the pilot pump to the pilot oil chamber via the second pipeline, A neutral position for leading the pilot pressure oil discharged from the pilot pump to the pilot oil chamber via the third pipeline, Including, The controller, When the pilot oil temperature detected by the second temperature sensor is lower than the main circuit oil temperature detected by the first temperature sensor, and the absolute value of the difference between the main circuit oil temperature detected by the first temperature sensor and the pilot oil temperature detected by the second temperature sensor is larger than a predetermined threshold value, a first switching command signal for instructing switching to the warm-up position is output to the direction switching valve, When the pilot oil temperature detected by the second temperature sensor is higher than the main circuit oil temperature detected by the first temperature sensor, and the absolute value is larger than the predetermined threshold value, a second switching command signal for instructing switching to the cooling position is output to the direction switching valve, When the absolute value is less than or equal to the predetermined threshold value, a third switching command signal for instructing switching to the neutral position is output to the direction switching valve. A working machine characterized by the above. **Claim 2** In the working machine according to Claim 1, In the first pipeline, a throttle for restricting the flow rate of the pilot pressure oil and heating the pilot pressure oil is provided. A working machine characterized by the above. **Claim 3** In the working machine according to Claim 1, In the first pipeline, a branch pipeline branched from a main pipeline connected to the discharge side of the main pump and through which a part of the pressure oil discharged from the main pump flows is connected. In the branch pipeline, a merging device for reducing the pressure of the pressure oil and merging it with the pilot pressure oil is provided. The controller, when the pilot oil temperature detected by the second temperature sensor is lower than the main circuit oil temperature detected by the first temperature sensor and the absolute value is greater than the predetermined threshold value, outputs a merging command signal for instructing to merge the depressurized pressure oil with the pilot pressure oil to the merging device. A working machine characterized by the above. **Claim 4** In the working machine according to Claim 1, further includes a mode selection device for selecting a warm-up mode for heating the pilot pressure oil and a cooling mode for cooling the pilot pressure oil. The controller, when the pilot oil temperature detected by the second temperature sensor is lower than the main circuit oil temperature detected by the first temperature sensor and the absolute value is greater than the predetermined threshold value, and the warm-up mode is selected by the mode selection device, outputs the first switching command signal to the direction switching valve. when the pilot oil temperature detected by the second temperature sensor is higher than the main circuit oil temperature detected by the first temperature sensor and the absolute value is greater than the predetermined threshold value, and the cooling mode is selected by the mode selection device, outputs the second switching command signal to the direction switching valve. A working machine characterized by the above.

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