JP2023151967A - Work machine - Google Patents

Abstract

To provide a work machine that can efficiently warm up hydraulic oil by a simple method without reducing fuel efficiency during work.SOLUTION: A work machine comprises a control device 520 which pumps oil from a hydraulic pump 511 to a hydraulic cylinder 460 without performing first control that controls a flow rate of the hydraulic pump 511 so that a pressure in a hydraulic circuit 510 does not exceed a predetermined pressure, under a condition that a specific operation for maintaining a work machine 100 having the hydraulic cylinder 460 operated by hydraulic oil pumped from the hydraulic pump 511 in a specific posture is continued.SELECTED DRAWING: Figure 2

Description

The present invention relates to a work machine that can be easily warmed up without reducing fuel efficiency during work.

The hydraulic excavator is known to actively relieve the hydraulic oil and warm up the hydraulic oil by performing an input operation in the direction of extending the stick cylinder further from the position where the stick cylinder of the hydraulic excavator does not extend any further. It is being (See Patent Document 1)

In recent years, hydraulic excavators have been required to have low fuel consumption, and the flow rate of the hydraulic pump is controlled so as not to exceed the relief setting pressure set in the relief valve in the hydraulic circuit, and the hydraulic oil is not relieved. may be implemented.

Japanese Patent Application Publication No. 2011-43219

However, with a hydraulic excavator equipped with the above control, even if input is performed in the direction of extending the stick cylinder further from the position where the stick cylinder does not extend any further, the flow rate of the hydraulic pump cannot be increased under high pressure conditions. Therefore, there is a problem that the hydraulic oil cannot be warmed up efficiently.

In addition, in some aspects, while an input operation is being performed in the direction of extending the stick cylinder further from the position where the stick cylinder will not extend any further, other actuators may be operated unintentionally. Not only is there a problem with performance, but there is also the problem of not being able to secure enough pressure to relieve the hydraulic oil.

The present invention was made in view of the problems of the prior art described above, and its object is to provide a working machine that can efficiently warm up hydraulic oil in a simple manner without reducing fuel efficiency during work. be.

In order to solve the above-mentioned problems, the present invention provides a hydraulic pump that pumps oil through an oil passage to a hydraulic cylinder that moves a working machine, and a flow rate of the hydraulic pump that prevents the pressure in the oil passage from exceeding a predetermined pressure. a control device that causes a first control to be executed to control the work machine, and when the control device continues a specific operation to maintain the work machine in a specific posture, without executing the first control. This is a working machine that pumps oil from the hydraulic pump to the hydraulic cylinder.

The invention according to another aspect of the present invention is a working machine in which the control device executes a second control that increases the flow rate of the hydraulic pump without executing the first control.

In the invention according to another aspect of the present invention, the specific operation is performed when a first operating lever for operating the hydraulic cylinder is operated in a state where the cylinder stroke of the hydraulic cylinder has reached a stroke end, and the specific operation is performed to operate the other actuator. This is a work machine in which the operating position of the second operating lever is neutral.

The invention according to another aspect of the present invention is a working machine in which the first control reduces the flow rate of the hydraulic pump when the pressure in the oil passage is equal to or higher than a predetermined pressure.

The invention according to another aspect of the present invention is a working machine, wherein the oil passage has a relief valve, and the predetermined pressure is equal to or lower than the relief setting pressure of the relief valve.

The invention according to another aspect of the present invention is a working machine in which the pressure in the oil passage increases to a relief set pressure by the second control.

The invention according to another aspect of the present invention is a working machine in which the working machine is a hydraulic excavator, the working machine includes a boom and an arm, and the hydraulic cylinder is a boom cylinder or an arm cylinder.

According to the present invention, it is possible to provide a working machine that can be efficiently warmed up using a simple method without reducing fuel efficiency during work.

FIG. 1 is a left side view of a hydraulic excavator according to an embodiment of the present invention. 1 is a schematic diagram of a control system for a hydraulic excavator according to an embodiment of the present invention. It is a flowchart figure of the control flow of the hydraulic excavator concerning one embodiment of the present invention. FIG. 3 is a schematic diagram of a control system for a hydraulic excavator according to another embodiment of the present invention. It is a flowchart figure of the control flow of the hydraulic excavator based on other embodiment of this invention. It is a diagram.

Hereinafter, a hydraulic excavator 100 as a representative example of a working machine according to the present invention will be described in detail with reference to FIG. 1 as an example. Note that the direction in which the working device 400 is disposed on the revolving upper structure 300 is defined as the front, and the opposite direction is defined as the rear.

The hydraulic excavator 100 includes a self-propelled lower traveling body 200, an upper rotating body 300 rotatably supported on the lower traveling body 200, and a working machine supported vertically rotatably in front of the upper rotating body 300. The device includes a device 400 and a control system 500.

The working device 400 includes a swing post 410 supported to be horizontally rotatable at the tip of the upper revolving structure 300, a boom 420 supported to be vertically rotatable by the swing post 410, and a tip of the boom 420. An arm 430 is attached so as to be rotatable up and down, a bucket 450 is rotatably attached to the tip of the arm 430, and a bucket 450 is installed below the upper rotating body 300 to rotate the swing post 410 in the horizontal direction. a swing cylinder (not shown); a boom cylinder 460 installed in front and below the boom 420 to move the boom 420; an arm cylinder 470 installed above the boom 420 to move the arm 430; The bucket cylinder 480 is installed at a bucket cylinder 480 and moves a bucket 450 via a bucket link 440.

A posture detection device 490 is attached to the work device 400 in order to detect the posture of the work device. The arm angle potentiometer 491 is connected to the rotation axis via the arm 430 and the link mechanism to detect the rotation angle of the boom 420 and the arm 430, and swings around the pivot point between the swing post 410 and the boom 420. The boom angle potentiometer 492 is attached to the upper end of the post 410 and connected to the rotation axis via the boom 420 and link mechanism, and detects the rotation angle of the swing post 410 and the boom 420.

The lower traveling body 200 has a center frame (not shown) and a side frame 210 (only one side shown) that is symmetrically paired with the center frame and extends in the front and rear direction. A driving wheel 211 (only the left side shown) driven by a left running motor 516 is installed on the left side, and a plurality of idler wheels 212 (only the left side shown) are arranged toward one front end. 212 has a crawler belt 213 (only the left side shown) wrapped around it, the right side has a similar configuration, and an earth removal device 220 is attached to the rear of the center frame.

The upper revolving body 300 includes a counterweight 310 installed at the rear end, a fuselage frame 320 extending forward from the counterweight 310, and a cabin installed at the tip of the fuselage frame 320 and behind the swing post 410. 330, and an engine room 340 installed between the cabin 330 and the counter 310.

The engine room 340 includes an engine (not shown), a variable displacement pump 511 that is driven by the engine and pumps hydraulic fluid to a plurality of actuators that move the hydraulic excavator 100, such as the boom cylinder 460 and the arm cylinder 470, and the cabin 330. A control valve 515 that controls a plurality of actuators and a pilot pump 512 that generates the source pressure of the control signal pressure (pilot pressure) that is input to the regulator 511a to control the flow rate of the variable displacement pump 511 are arranged below. Multiple devices are installed.

Inside the cabin 330, a control device 331 and a cockpit 333 including a seat 332 are arranged.

The operating device 331 can operate each actuator via the control device 510 by outputting the operating direction and amount as an electrical signal.

The operating device 331 is installed on the left and right in front of the pilot's seat 333, and is installed upright on a left travel lever 334, a right travel lever 335 (not shown), and a console box located on the left and right sides of the seat 332, It is comprised of a left operating lever 336, a right operating lever 337 (not shown), etc. for operating or turning operations.

The left traveling lever 334 and the right traveling lever 335 are operated by tilting the operating levers back and forth so that the lower traveling body 200 moves in the direction opposite to where the earth removal device 220 is installed and the right traveling lever 335 moves to the left. The motor 213 and right travel motor 214 are rotated.

When the left operating lever 336 is tilted rearward, the cylinder rod of the arm cylinder 470 moves in the extending direction, and the arm 430 performs a cloud operation in which it rotates in the direction approaching the cabin 330.

When the left operating lever 336 is tilted forward, the cylinder rod of the arm cylinder 470 moves in the direction of contraction, and the arm 430 performs a dumping operation in which it rotates in the direction away from the cabin 330.

When the right operating lever 337 is tilted rearward, the cylinder rod of the boom cylinder 460 moves in the direction of extension and performs a boom-raising operation in which the boom rotates in the direction of rising.

When the right operating lever 337 is tilted forward, the cylinder rod of the boom cylinder 460 moves in the direction of contraction and performs a boom lowering operation in which the boom rotates in the direction of descending.

Since the cloud operation of the left operating lever 336 and the boom raising operation of the right operating lever 337 are operations in which the work equipment 400 approaches the center of the hydraulic excavator 100, the hydraulic excavator 100 is equipped with at least one of the arm cylinder 470, the boom cylinder 460, or By holding both cylinder rods at their stroke ends, they will not get in the way when working around the hydraulic excavator 100, and will be a safe posture for warming up the hydraulic excavator 100. be.

Further, since the arm cylinder 470 and the boom cylinder 460 are actuators that consume a large amount of hydraulic oil, warm-up can be performed efficiently by using these actuators.

Next, the control system 500 of the hydraulic excavator 100 will be explained using FIG. 2.

The control system 500 includes a hydraulic circuit 510, a control device 520, an operating device 331, and a posture detection device 490.

In the hydraulic circuit 510, a high-pressure hydraulic oil pipe extending from the variable displacement pump 511 is represented by a solid line, and a low-pressure hydraulic oil (pilot pressure) pipe extending from the pilot pump 512 is represented by a dotted line.

The hydraulic circuit 510 includes a variable displacement pump 511 that controls the flow rate of hydraulic oil by inputting pilot pressure reduced by an electromagnetic proportional valve 511b to a regulator 511a, and a center bypass that extends from the variable displacement pump 511 to a hydraulic oil tank 513. It is composed of at least a flow path 514 and a control valve 515 that distributes the hydraulic oil flowing through the center bypass flow path 514 to the actuators according to the operation of the operating device 331.

The control valves 515 schematically show only a directional switching valve 515a that controls the hydraulic oil flowing to the left travel motor 516 and a directional switching valve 515b that controls the oil flowing to the boom cylinder 460, and controls the oil flowing to other actuators. The directional switching valve to be controlled is omitted.

The pilot pressure reduced from the electromagnetic proportional valves 518a1 and 518a2 is input to the pilot pressure input port of the directional switching valve 515a according to the direction and amount of operation of the left traveling lever 334, so that the directional switching valve 515a is activated. The spool 515a slides, and hydraulic oil according to the opening amount of the spool flows to the left travel motor.

The pilot pressure reduced from the electromagnetic proportional valves 518b1 and 518b2 is input to the pilot pressure input port of the directional control valve 515b according to the direction and amount of operation of the right operating lever 337, so that the spool slides. The boom cylinder 460 moves, and hydraulic oil flows into the boom cylinder 460 according to the opening amount.

A relief valve 517 and a pressure gauge 511b that detects the pressure of the hydraulic circuit 510 are installed upstream of the center bypass flow path 514 (near the discharge port of the variable displacement pump 511), and the pressure of the hydraulic circuit 510 is detected by the relief valve 517. When the relief setting pressure set at 517 is reached, the hydraulic oil in the hydraulic circuit 510 flows out to the hydraulic oil tank 513 via the relief valve 517.

The control device 520 is an ECU (electronic control unit), and includes a signal input section including an input buffer that converts the signal level of a digital input signal and an AD converter that converts an analog input signal to digital, and a control amount from various input signals. It is composed of a calculation section 521 consisting of a microcomputer that performs calculations, and a signal output section consisting of an output driver that converts the output signal of the microcomputer into a form of a drive signal that drives an actuator.

The signal input to the signal input section of the control device 520 is represented by a chain line with an arrow pointing toward the control device 520 at the tip, and is a signal detected from the attitude detection device 490, the operating device 331, and the pressure gauge 511b.

The signal output from the signal output section of the control device 520 is expressed by a dashed-dotted line with an arrow pointing toward the electromagnetic proportional valves 511c and 518, which are actuators, and the pilot pressure is input to the pilot pressure input port of the control valve 515. The pilot pressure is input to an electromagnetic proportional valve 518 which inputs the pilot pressure to the regulator 511a.

The calculation unit 521 includes an actuator required flow rate calculation unit 522, a posture calculation unit 523, and a pump flow rate calculation unit 524.

The actuator required flow rate calculation section 522 calculates the operating speed of the actuator (the flow rate of hydraulic fluid required by the actuator) from the signal corresponding to the operation amount of the operating device 331 input to the signal input section of the control device 520, and A signal amount corresponding to the opening amount of the spool of the control valve 522 to be output from the signal output section of the control valve 520 to the electromagnetic proportional valve 518 is calculated.

Posture calculation unit 523 calculates the height of boom 420 (cylinder stroke of boom cylinder 460) from a signal corresponding to the angle of boom angle potentiometer 492 input to the signal input unit of control device 520.

The pump flow rate calculation section 524 calculates the pressure calculated from the pressure of the pressure gauge 511b and the flow rate of the variable displacement pump 511 calculated from the sum of the flow rates of hydraulic oil required by each actuator calculated by the actuator required flow rate calculation section 522 as relief. A first control is performed in which the flow rate of the variable displacement pump 511 is calculated so as to be lower than a predetermined pressure set below the set pressure, and a value input to the corresponding electromagnetic proportional valve 511c is calculated.

The pump flow rate calculation unit 524 determines that when a predetermined period of time has elapsed with the cylinder stroke of the boom cylinder 460 calculated by the attitude calculation unit 523 reaching the stroke end, the operation signal of the right operation lever 337 is sent to the signal input unit of the control device 520. and the signal from the operating device 331 (including the left travel lever) other than the operating lever 337 is not input to the signal input section of the control device 520 (the operating lever is in the neutral position). A second control is performed in which a value input to the electromagnetic proportional valve 511c is calculated so that the flow rate of the variable displacement pump 511 reaches the relief setting pressure while stopping the control.

According to the above-mentioned control, when the operator is performing normal operations, the hydraulic oil is not discharged from the relief valve 517 into the hydraulic oil tank 513 unnecessarily, so that the fuel efficiency of the hydraulic excavator is improved.

In addition, the control device 520 automatically detects a specific warm-up operation by the operator and appropriately controls the flow rate of the variable displacement pump 511, so that warm-up can be easily and efficiently performed.

Furthermore, since the specific posture of the hydraulic excavator 100 during warming up is a stationary posture, it can be warmed up safely, and the specific posture is a posture in which the work equipment 400 does not disturb surrounding workers. Therefore, warm-up can be performed more safely.

Next, the control flow will be explained using FIG. 3. FIG. 3 is a flowchart relating to the control method.

A boom raising operation for tilting the right operating lever 337 backward is started. (S1) The control device 520 attempts to set the flow rate of the variable displacement pump 511 according to the operation amount of the right operation lever 337, but the pressure in the hydraulic circuit 500 is lower than the relief setting pressure. A first control is performed to correct the flow rate of the variable displacement pump 511 so that

When the right operating lever 337 is tilted backward, the cylinder stroke of the boom cylinder 460 reaches the stroke end, 5 seconds have passed, and the specific operating conditions are met, in which the operating devices 331 other than the right operating lever 337 are in a neutral state. If (S2: YES), the control device 520 stops the first control and adjusts the pressure of the hydraulic circuit 500 to the variable displacement pump 511 according to the operation amount of the right operation lever 337 so that the pressure of the hydraulic circuit 500 becomes the relief setting pressure. A second control for controlling the flow rate of the capacity pump 511 is performed. (S3)

When the right operating lever 337 is placed in a neutral state or when an operating device 331 other than the right operating lever 337 is operated (S4), the control device 520 stops the second control and executes the first control. (S5)

The control device 500 repeatedly executes the processes of steps S1 to S5 above. The flowchart shown in FIG. 3 is only an example, and processes may be added or omitted as appropriate, and the order of processes may be changed as appropriate.

Next, another embodiment of the present invention will be described using FIG. 4.

4 is the same as the control system 500 of the embodiment of FIG. 2, but the schematically shown directional control valve of the control valve 515 and the omitted directional control valve are different, and accordingly, the related actuators and electromagnetic proportional valves are different. However, since there is no difference in the effect of the invention, only the parts that are different from the embodiment of FIG. 2 will be described.

The control valve 515 schematically shows only a directional switching valve 515a that controls the hydraulic oil flowing to the left travel motor 516 and a directional switching valve 515c that controls the oil flowing to the arm cylinder 470, and controls the oil flowing to other actuators. The directional switching valve to be controlled is omitted.

The pilot pressure reduced from the electromagnetic proportional valves 518c1 and 518c2 according to the direction and amount of operation of the left operating lever 336 is input to the pilot pressure input port of the directional control valve 515c, so that the spool slides. The arm cylinder 470 moves, and hydraulic oil flows into the arm cylinder 470 according to the opening amount.

Posture calculation unit 523 calculates the height of arm 430 (cylinder stroke of arm cylinder 480) from a signal corresponding to the angle of arm angle potentiometer 491 input to the signal input unit of control device 520.

The pump flow rate calculation unit 524 determines that when a predetermined period of time has elapsed with the cylinder stroke of the arm cylinder 470 calculated by the posture calculation unit 523 reaching the stroke end, the operation signal of the left operation lever 336 is sent to the signal input unit of the control device 520. and the signal from the operating device 331 (including the left travel lever) other than the left operating lever 336 is not input to the signal input section of the control device 520 (the operating lever is in the neutral position). The first control is stopped and the second control is executed.

Next, referring to FIG. 5, a control flow for another embodiment will be described. FIG. 5 is a flowchart relating to a control method for another embodiment.

An arm cloud operation for tilting the left operating lever 336 backward is started. (S6) The control device 520 tries to set the flow rate of the variable displacement pump 511 according to the operation amount of the left operation lever 336, but the pressure in the hydraulic circuit 500 is lower than the relief setting pressure. A first control is performed to correct the flow rate of the variable displacement pump 511 so that

When the left operating lever 336 is tilted backward, the cylinder stroke of the arm cylinder 470 reaches the stroke end, 5 seconds have elapsed, and the specific operating conditions are met, in which the operating devices 336 other than the left operating lever 337 are in a neutral state. If (S7: YES), the control device 520 stops the first control and adjusts the pressure of the hydraulic circuit 500 to the variable displacement pump 511 according to the operation amount of the left operation lever 3336 so that the pressure of the hydraulic circuit 500 becomes the relief setting pressure. A second control for controlling the flow rate of the capacity pump 511 is performed. (S8)

When the left operating lever 336 is placed in the neutral state or when the operating device 331 other than the left operating lever 337 is operated (S9), the control device 520 stops the second control and executes the first control. (S10)

The control device 500 repeatedly executes the processes of steps S6 to S7 above. The flowchart shown in FIG. 3 is only an example, and processes may be added or omitted as appropriate, and the order of processes may be changed as appropriate.

Further, as a modified example, when the left operating lever 336 and the right operating lever 337 are tilted backward, the cylinder strokes of the arm cylinder 470 and the boom cylinder 460 reach their stroke ends, and 5 seconds have passed, and the left operating lever 336 and the right operating lever An operating condition in which the operating device 331 other than the lever 337 is in a neutral state can be set as a specific operating condition.

By starting warm-up under these operating conditions, it is not only possible to warm up efficiently in a simple manner without reducing fuel efficiency during work, but also to store the work equipment 400 in its most compact state. However, safety can also be improved because the aircraft can be stopped and warmed up.

The various configurations described in the other embodiments, modifications, or embodiments described above can be employed in appropriate combinations.

Although a hydraulic excavator has been described above as an example of a working machine, the working machine is not limited to a hydraulic excavator, and may be another working machine such as a wheel loader or a compact track loader.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and can be expanded or modified without departing from the spirit of the invention.

The present invention relates to a working machine and has industrial applicability.

100 Hydraulic excavator (work machine) 460 Boom cylinder (actuator) 510 Hydraulic circuit 511 Variable displacement pump (hydraulic pump) 520 Control device

Claims (8)

A hydraulic pump that pumps oil through an oil path to a hydraulic cylinder that moves a work machine, and a control device that executes a first control that controls the flow rate of the hydraulic pump so that the pressure in the oil path does not exceed a predetermined pressure. and, when the control device continues a specific operation for maintaining the working machine in a specific posture, pressure-feeding oil from the hydraulic pump to the hydraulic cylinder without executing the first control. A working machine that does. 2. The working machine according to claim 1, wherein the control device executes a second control that increases the flow rate of the hydraulic pump without executing the first control. The specific operation is performed when the cylinder stroke of the hydraulic cylinder reaches the stroke end, the operating lever that operates the hydraulic cylinder is operated, and all other operating levers that operate actuators that operate other than the working equipment are operated. 4. The work machine of claim 3, wherein the position is neutral. The working machine according to claim 3, wherein the first control reduces the flow rate of the hydraulic pump when the pressure in the oil passage is equal to or higher than a predetermined pressure. The working machine according to claim 4, wherein the oil passage has a relief valve, and the predetermined pressure is lower than a relief setting pressure of the relief valve. . The working machine according to claim 5, wherein the second control controls the flow rate of the hydraulic pump according to the amount of operation of the operating lever. The working machine according to claim 6, wherein the second control causes the pressure in the oil passage to rise to a relief set pressure. 8. The working machine according to claim 1, wherein the working machine is a hydraulic excavator, the working machine includes a boom and an arm, and the hydraulic cylinder is a boom cylinder or an arm cylinder.