Work machine, program, and recording medium therefor

Abstract

The present invention makes it possible to secure an operation speed of a work tool when the work tool and an arm are operated in combination.　This work machine comprises: a work tool cylinder (C5) and an arm cylinder (C4) that are driven with a hydraulic oil; a work tool (17) that is swung by the work tool cylinder; an arm (16) that is swung by the arm cylinder; an operation member (41) that operates the arm cylinder; an arm control valve (V7) that changes the flow rate of the hydraulic oil supplied to the arm cylinder; and a control device (U1) that controls the flow rate of the hydraulic oil supplied from the arm control valve to the arm cylinder by controlling the operation of the arm control valve according to an operation amount of the operation member, wherein the control device controls the operation of the arm control valve according to the operation amount of the operation member so as to reduce the flow rate of the hydraulic oil supplied from the arm control valve to the arm cylinder when the work tool and the arm are operated in combination, in comparison to when the arm cylinder is operated independently with the same operation amount as the operation amount of the operation member for the arm cylinder when the work tool and the arm are operated in combination.

Description

Work machine, program, and recording medium thereof

[0001] The present invention relates to a work machine such as a backhoe, a program, and a recording medium.

[0002] Conventionally, a work machine disclosed in Patent Document 1 is known.

[0003] The work machine disclosed in Patent Document 1 includes a working device mounted on the machine body. The working device includes a boom whose proximal end is pivotally supported by a support bracket provided on the machine body and is swingable up and down, an arm whose proximal end is pivotally supported on the distal end side of the boom and is swingable, and a working tool swingably attached to the distal end side of the arm. The boom, arm, and working tool are driven by a hydraulic cylinder.

[0004] Japanese Patent Application Laid-Open Publication "JP-A-2009-79366"

[0005] By the way, problems may occur if the operating speed of the working tool is set too fast. For example, during work, when the load acting on the working tool is removed from a state where the load is acting on the working tool, the operation of the working tool may suddenly become faster. Considering such a case, the operating speed of the working tool is set to be somewhat suppressed.

[0006] In addition, the working tool may be operated in combination (simultaneously) with the arm. However, when the working tool and the arm are operated in combination, the operating speeds of the working tool and the arm may decrease. Since the operating speed of the working tool is originally set slow, when the working tool and the arm are operated in combination, the operating speed of the working tool becomes slower than when the working tool is operated alone, and there is a problem that the operator tends to feel that the operating speed of the working tool is insufficient.

[0007] In view of the above problems, an object of the present invention is to ensure the operating speed of the working tool when the working tool and the arm are operated in combination.

[0008] A work machine according to one aspect of the present invention comprises a work tool cylinder and an arm cylinder driven by hydraulic fluid, a work tool oscillated by the work tool cylinder, an arm oscillated by the arm cylinder, an operating member for operating the arm cylinder, an arm control valve for changing the flow rate of hydraulic fluid supplied to the arm cylinder, and a control device for controlling the flow rate of hydraulic fluid supplied from the arm control valve to the arm cylinder by controlling the operation of the arm control valve according to the amount of operation of the operating member, wherein when the work tool and the arm are operated in combination, the control device controls the operation of the arm control valve according to the amount of operation of the operating member to reduce the flow rate of hydraulic fluid supplied from the arm control valve to the arm cylinder compared to when the arm cylinder is operated alone with the same amount of operation of the operating member as when the arm cylinder is operated in combination.

[0009] With the above configuration, it is possible to ensure the operating speed of the work tool when the work tool and the arm are operated in combination.

[0010] This is a side view of the work machine. This is a top view of the work machine. This is a schematic diagram of the hydraulic system. This is a circuit diagram of a part of the hydraulic system. This is a circuit diagram of a part of the control valve. This is a circuit diagram of another part of the control valve. This is a circuit diagram of yet another part of the control valve. This is a simplified diagram of the control system. This is a diagram showing the relationship between the operating amount of the operating member and the flow rate of the hydraulic fluid. This is a diagram showing the pilot control pressure applied to the arm control valve when the bucket and arm are operated individually and in combination. This is a configuration diagram showing another form of the control valve, etc. This is a configuration diagram showing yet another form of the control valve, etc.

[0011] The following describes one embodiment of the present invention, with appropriate reference to the drawings.

[0012] Figure 1 is a schematic side view showing the overall configuration of the work machine 1 according to this embodiment. Figure 2 is a schematic top view of the work machine 1. In this embodiment, a backhoe, which is a slewing work machine, is exemplified as the work machine 1.

[0013] As shown in Figures 1 and 2, the work machine 1 comprises a machine body (turntable) 2, a travel device 3, and a work device 4. The machine body 2 is equipped with a cabin 5. Inside the cabin 5 is a driver's seat 6 where the operator (driver) sits.

[0014] In this embodiment, the direction towards the front of the operator seated in the driver's seat 6 of the work machine 1 (direction of arrow A1 in Figures 1 and 2) is described as the front (front of the machine), the direction towards the rear of the operator (direction of arrow A2 in Figures 1 and 2) is described as the rear (rear of the machine), and the direction of arrow K1 in Figures 1 and 2 is described as the front-rear direction. Furthermore, the direction towards the left of the operator (front side in Figure 1, direction of arrow A3 in Figure 2) is described as the left, and the direction towards the right of the operator (back side in Figure 1, direction of arrow A4 in Figure 2) is described as the right.

[0015] Furthermore, the horizontal direction, which is perpendicular to the longitudinal direction (aircraft longitudinal direction) K1, will be described as the aircraft width direction K2 (see Figure 2). The direction from the center of the aircraft 2's width toward the right or left will be described as the outward direction of the aircraft width. In other words, the outward direction of the aircraft width is the direction away from the center of the aircraft 2's width in the aircraft width direction K2. The direction opposite to the outward direction of the aircraft width will be described as the inward direction of the aircraft width. In other words, the inward direction of the aircraft width is the direction approaching the center of the aircraft 2's width in the aircraft width direction K2.

[0016] The travel device 3 is a device that supports the machine body 2 so that it can move. As shown in Figures 1 and 2, the travel device 3 has a travel frame 3A, a first travel device 3L provided on the left side of the travel frame 3A, and a second travel device 3R provided on the right side of the travel frame 3A. The first travel device 3L and the second travel device 3R are crawler-type travel devices. The travel device 3 is driven by a travel motor M1 which is composed of a hydraulic motor (hydraulic actuator). Specifically, the first travel device 3L is driven by the first travel motor ML, and the second travel device 3R is driven by the second travel motor MR.

[0017] A dozer device 7 is mounted on the front of the traveling device 3. The dozer device 7 is driven by a dozer cylinder C1. The dozer cylinder C1 is composed of a hydraulic cylinder (hydraulic actuator), and the blade 7A of the dozer device 7 is raised and lowered by extending and retracting the dozer cylinder C1.

[0018] As shown in Figure 1, the machine body 2 is supported on the running gear 3 (running frame 3A) so as to be able to rotate around the pivot axis X1 via a slewing bearing 8. The pivot axis X1 is an axis (longitudinal axis) that extends in the vertical direction and passes through the center of the slewing bearing 8.

[0019] As shown in Figure 2, the cabin 5 is mounted on one side (left side) of the aircraft body 2 in the width direction K2. The engine E1 is mounted on the other side (right side) of the aircraft body 2 in the width direction K2. The engine E1 is a diesel engine. The engine E1 may also be a gasoline engine, an electric motor, or a hybrid type having both an engine and an electric motor.

[0020] A pressurized oil supply unit 18 is provided at the rear of the prime mover E1. The pressurized oil supply unit 18 is driven by the power of the prime mover E1 to pressurize and discharge the hydraulic fluid used in the hydraulic drive unit. The hydraulic drive unit is, for example, a hydraulic actuator equipped on the work machine 1.

[0021] As shown in Figure 1, the aircraft body 2 has a base plate (hereinafter referred to as the rotating base plate) 9 that rotates around a rotation axis X1. The rotating base plate 9 is made of steel plate or the like and constitutes the bottom of the aircraft body 2. A reinforcing member, a longitudinal rib 9A, is provided on the upper surface of the rotating base plate 9, extending from the front to the rear. In addition to the longitudinal rib 9A, members that support mounted equipment and other items mounted on the aircraft body 2 are also provided on the rotating base plate 9, thereby forming the rotating frame that forms the skeleton of the aircraft body 2.

[0022] As shown in Figure 1, the rear of the machine body 2 is equipped with a weight 10 for balancing the weight with the work device 4, a fuel tank T1 for storing fuel for the prime mover E1, and a hydraulic oil tank T2 for storing hydraulic oil.

[0023] As shown in Figure 2, a slewing motor MT is positioned at the front of the machine body 2 (slewing base plate 9) and in the center of the machine body width direction K2. This slewing motor MT drives the slewing base plate 9 to rotate around the slewing axis X1. The slewing motor MT is a hydraulic motor (hydraulic actuator). A swivel joint S1, which is a rotary joint that allows hydraulic fluid to flow between the hydraulic equipment on the machine body 2 side and the hydraulic equipment on the traveling device 3 side, is provided at the position of the slewing axis X1. A control valve (hydraulic equipment) CV is positioned behind the swivel joint S1. The control valve CV is a sectional type composite control valve (hydraulic equipment) having multiple control valves stacked and coupled in the vertical direction.

[0024] A control device U1 is provided below the cabin 5. The control device U1 includes a computer equipped with a processing circuit that includes one or more processors. The processors are, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit). The control device U1 is connected to a plurality of devices mounted on the work machine 1 via a network such as CAN, ISOBUS, LIN, or FlexRay in order to control the plurality of devices.

[0025] The computer (processor) executes a program (control program) to perform processing in the control device U1 of the work machine 1 (various control and setting processes, as described later).

[0026] The above program is recorded in a computer-readable format on a recording medium (such as an HDD, SSD, CD-ROM, or DVD-ROM, which is communicated to the control device U1). By allowing the computer to read the above program from the recording medium, the computer can be made to execute a program that performs processing on the control device U1. The recording medium may also be one provided by the control device U1.

[0027] A control device 1B for operating the work machine 1 is provided inside the cabin 5. The control device 1B is installed in front of the driver's seat 6. The driver's seat 6 and the control device 1B constitute the operating section 1C.

[0028] As shown in Figure 2, the aircraft body 2 has a support bracket 13. The support bracket 13 is fixed to the front of the longitudinal rib 9A and is provided to protrude forward from the aircraft body 2.

[0029] As shown in Figures 1 and 2, the front part of the support bracket 13 (the part that protrudes from the machine body 2) is attached so as to be able to swing around the swing axis X2, which is the axis through which the swing bracket 14 extends in the vertical direction.

[0030] As shown in Figure 1, the working device 4 is supported on the swing bracket 14 (machine body 2).

[0031] The work device 4 includes a boom 15 supported on the machine body 2 so as to be able to swing up and down (swing in the vertical direction), an arm 16 swingably connected to the boom 15, and a bucket (working tool) 17 swingably connected to the arm 16.

[0032] The base of the boom 15 is pivotally attached to the upper part of the swing bracket 14 so as to be rotatable around the horizontal axis (the axis extending in the width direction K2 of the machine body) when the boom 15 is facing the front of the machine body. This allows the boom 15 to swing in the vertical direction.

[0033] The arm 16 is pivotally attached to the boom 15 so as to be rotatable around its horizontal axis when the boom 15 is facing forward. This allows the arm 16 to swing in the forward / backward direction K1 or in the up / down direction. The arm 16 can also swing in the arm cloud direction D1, which is the direction towards the boom 15, and in the arm dump direction D2, which is the direction away from the boom 15.

[0034] In this embodiment, a bucket 17 is shown as a work tool. Alternatively, in place of the bucket, other work tools (attachments) such as pallet forks and manifold forks, or work tools with hydraulic actuators (hydraulic attachments) such as grapples, hydraulic crushers, angle brooms, earth augers, snow blowers, sweepers, mowers, and hydraulic breakers can be attached.

[0035] The bucket 17 is pivotally supported at its base on the tip side of the arm 16 via a pivot 61. The bucket 17 also has a claw portion 62 on the tip side (opposite the base).

[0036] Furthermore, the bucket 17 is rotatable around a horizontal axis about the pivot 61 when the boom 15 is facing the front of the machine, and the bucket 17 is swingable in the bucket cloud direction D4, which is the direction toward the arm 16, and in the bucket dump direction D3, which is the direction toward the arm 16. In other words, the bucket 17 is mounted on the arm 16 so as to be able to perform scooping and dumping operations. The scooping operation is the operation of swinging the tip 62a of the claw portion 62 of the bucket 17 toward the arm 16 (bucket cloud direction D4), for example, when scooping up soil or sand. The dumping operation is the operation of swinging the tip 62a of the bucket 17 toward the arm 16 (bucket dump direction D3), for example, when dropping (discharging) the scooped soil or sand.

[0037] The swing bracket 14 is swingable by the extension and retraction of the swing cylinder C2 located inside the machine body 2. The boom 15 is swingable up and down by the extension and retraction of the boom cylinder C3. The arm 16 is swingable in the arm cloud direction D1 and the arm dump direction D2 by the extension and retraction of the arm cylinder C4. The bucket 17 is swingable in the bucket cloud direction D4 and the bucket dump direction D3 by the extension and retraction of the bucket cylinder (work tool cylinder) C5. The swing cylinder C2, boom cylinder C3, arm cylinder C4, and bucket cylinder C5 are composed of hydraulic cylinders (hydraulic actuators). The various hydraulic actuators ML, MR, MT, C1 to C6 equipped on the work machine 1 are driven by hydraulic fluid.

[0038] Next, with reference to Figures 3 to 7, the hydraulic system for operating the various hydraulic actuators ML, MR, MT, C1 to C6 equipped on the work machine 1 will be described.

[0039] As shown in Figure 3, the hydraulic system includes a control valve CV, a pressurized oil supply unit 18, and a flow control unit 19. The control valve CV is composed of control valves V1 to V10 that control various hydraulic actuators ML, MR, MT, and C1 to C6, an inlet block B2 for pressurized oil intake, and a pair of outlet blocks B1 and B3 for pressurized oil discharge, all arranged in one direction and integrated into a single unit.

[0040] As shown in Figure 3, in this embodiment, the control valve CV is configured by arranging the following in order (arranged from right to left in Figure 3): the first outlet block B1, the bucket control valve (work tool control valve) V1 that controls the bucket cylinder C5, the boom control valve V2 that controls the boom cylinder C3, the first control valve V3 for the dozer that controls the dozer cylinder C1, the second travel control valve V4 that controls the travel motor MR of the second travel device 3R, the inlet block B2, the first travel control valve V5 that controls the travel motor ML of the first travel device 3L, the second control valve V6 for the dozer that controls the dozer cylinder C1, the arm control valve V7 that controls the arm cylinder C4, the slewing control valve V8 that controls the slewing motor MT, the swing control valve V9 that controls the swing cylinder C2, the SP control valve V10 that controls the attachment actuator (hydraulic actuator) C6 equipped on the hydraulic attachment when the hydraulic attachment is attached as a work tool instead of the bucket 17, and the second outlet block B3, and connecting them to each other.

[0041] As shown in Figures 4 to 7, each control valve V1 to V10 is configured by incorporating directional control valves DV1 to DV10 and a pressure compensation valve (compensator valve) V11 within the valve body. Directional control valves DV1 to DV10 are valves that switch the direction of hydraulic fluid to the hydraulic actuators ML, MR, MT, C1 to C6 that are to be controlled. Directional control valves DV1 to DV10 (control valves V1 to V10) also change the flow rate of hydraulic fluid supplied to the hydraulic actuators ML, MR, MT, C1 to C6 that are to be controlled.

[0042] The pressure compensation valve V11 is located on the downstream side of the pressurized oil supply to the directional control valves DV1 to DV10 and on the upstream side of the pressurized oil supply to the hydraulic actuators ML, MR, MT, and C1 to C6 that are to be controlled. When multiple of the control valves V1 to V10 are used, the pressure compensation valve V11 functions to adjust the load between the hydraulic actuators ML, MR, MT, and C1 to C6.

[0043] In the first outlet block B1, a first relief valve V12 and a first unloading valve V13 are incorporated, and in the inlet block B2, a travel independent valve V14 is incorporated. The first relief valve V12 is a main relief valve that defines the pressure of the hydraulic oil discharged from a first pressure oil discharge port P1, which will be described later.

[0044] The travel independent valve V14 is composed of a direct-acting spool type switching valve and is also composed of a pilot-operated switching valve that is switched (piloted) by a pilot control pressure.

[0045] In the second outlet block B3, a second relief valve V15 and a second unloading valve V16 are incorporated. The second relief valve V15 is a main relief valve that defines the pressure of the hydraulic oil discharged from a second pressure oil discharge port P2, which will be described later.

[0046] Each of the direction switching valves DV1 to DV10 is composed of a direct-acting spool type switching valve. Also, each of the direction switching valves DV1 to DV10 is a control valve that is electrically controlled by a control device U1. Specifically, for example, a pilot type proportional solenoid valve is adopted for each of the direction switching valves DV1 to DV10. A pilot type proportional solenoid valve is a valve that moves a spool by a pilot control pressure controlled by a proportional solenoid to control the direction and flow rate of the hydraulic oil flow. Specifically, a pilot type proportional solenoid valve is a two-stage direction / flow rate control valve that employs a proportional electromagnetic pressure reducing valve having two proportional solenoids in the pilot section. The flow rate is controlled by changing the input current to the proportional solenoid, and the direction is controlled by applying current to either one of the two proportional solenoids.

[0047] As shown in FIG. 4, the hydraulic pump as a pressure oil supply source in this hydraulic system is equipped with a first pump 21 for supplying hydraulic oil to operate the hydraulic actuators ML, MR, MT, C1 to C6, and a second pump 22 for supplying signal pressure oil such as a pilot control pressure and a detection signal. These first pump 21 and second pump 22 are provided in the pressure oil supply unit 18 and are driven by a prime mover E1.

[0048] The first pump 21 is a variable displacement hydraulic pump. In this embodiment, it is a swash plate type variable displacement axial pump having the function of an equal flow double pump that discharges an equal amount of hydraulic oil from two independent pressure oil discharge ports P1 and P2. Specifically, the first pump 21 employs a split flow type hydraulic pump having a mechanism for alternately discharging hydraulic oil from one piston - cylinder barrel kit to discharge grooves formed inside and outside the valve plate.

[0049] One of the pressure oil discharge ports discharged from the first pump 21 is referred to as the first pressure oil discharge port P1, and the other pressure oil discharge port is referred to as the second pressure oil discharge port P2.

[0050] In this embodiment, the pressure oil discharge ports discharged from the hydraulic pump having two pump functions are the first and second pressure oil discharge ports P1 and P2. However, the pressure oil discharge port of one of the two separately formed hydraulic pumps may be used as the first pressure oil discharge port, and the pressure oil discharge port of the other hydraulic pump may be used as the second pressure oil discharge port.

[0051] The pressure oil supply unit 18 is equipped with a pressing piston 23 for pressing the swash plate of the first pump 21 and a flow compensation piston 24 for controlling the swash plate of the first pump 21.

[0052] The first pump 21 is configured such that the swash plate is pressed in the direction of increasing the pump flow rate via the pressing piston 23 by the self - pressure of the first pump 21, and a force opposing the pressing force of the pressing piston 23 is applied to the swash plate by the flow compensation piston 24. By controlling the pressure acting on the flow compensation piston 24, the discharge flow rate of the first pump 21 is controlled.

[0053] Therefore, when the pressure acting on the flow compensation piston 24 leaks, the first pump 21 discharges the maximum flow rate with the swash plate angle becoming MAX.

[0054] As shown in Figure 4, the flow control unit 19 controls the swash plate of the first pump 21, and this swash plate control of the first pump 21 is performed by controlling the pressure acting on the flow compensation piston 24 by controlling the flow compensation valve V17 equipped in the flow control unit 19.

[0055] Furthermore, the pressurized oil supply unit 18 is equipped with a spring 25 and a spool 26 for controlling the pump horsepower (torque) of the first pump 21. When the discharge pressure of the first pump 21 reaches a preset pressure, the unit is configured to limit the horsepower (torque) absorbed by the first pump 21 from the prime mover E1.

[0056] The second pump 22 is composed of a constant-capacity gear pump, and the oil discharged from the second pump 22 is discharged from the third pressure oil discharge port P3.

[0057] The first pressurized oil discharge port P1 is connected to the inlet block B2 via the first discharge path a, and the second pressurized oil discharge port P2 is connected to the inlet block B2 via the second discharge path b.

[0058] The first discharge passage a is connected to the first pressurized oil supply passage d, which is formed to go from the inlet block B2 through the valve body of the second travel control valve V4 → the valve body of the first control valve V3 for the dozer → the valve body of the boom control valve V2 → the valve body of the bucket control valve V1 to the first outlet block B1, where it branches off (at the end of the flow path) and is connected to the first relief valve V12 and the first unload valve V13.

[0059] The hydraulic fluid can be supplied from the first pressurized oil supply passage d to the directional control valves DV4, DV3, DV2, and DV1 of the second travel control valve V4, the first control valve V3 for the dozer, the boom control valve V2, and the bucket control valve V1, respectively, via the pressurized oil branch passage f.

[0060] The first relief valve V12 and the first unload valve V13 are connected to the drain oil passage g. The drain oil passage g is formed to go from the first outlet block B1 through the valve body of the bucket control valve V1 → the valve body of the boom control valve V2 → the valve body of the first control valve V3 for the dozer → the valve body of the second travel control valve V4 → the inlet block B2 → the valve body of the first travel control valve V5 → the valve body of the second control valve V6 for the dozer → the valve body of the arm control valve V7 → the valve body of the slewing control valve V8 → the valve body of the swing control valve V9 → the valve body of the SP control valve V10 to the second outlet block B3. The hydraulic fluid flowing through the drain oil passage g is discharged from the second outlet block B3 to the hydraulic fluid tank T2.

[0061] The second discharge passage b is connected to the second pressurized oil supply passage e. The second pressurized oil supply passage e is formed to go from the inlet block B2 through the valve body of the first travel control valve V5 → the valve body of the second control valve V6 for the dozer → the valve body of the arm control valve V7 → the valve body of the swing control valve V8 → the valve body of the swing control valve V9 → the valve body of the SP control valve V10 to the second outlet block B3. At the second outlet block B3 (at the end of the flow path), it branches off and is connected to the second relief valve V15 and the second unload valve V16.

[0062] The hydraulic fluid can be supplied from the second pressurized oil supply passage e to the first travel control valve V5, the second control valve V6 for the dozer, the arm control valve V7, the slewing control valve V8, the swing control valve V9, and the SP control valve V10, respectively, via the pressurized oil branch passage h.

[0063] The hydraulic fluid supplied to each control valve V1 to V10 is supplied to and discharged from each hydraulic actuator ML, MR, MT, C1 to C6. In other words, the hydraulic system has a hydraulic circuit that supplies and discharges hydraulic fluid to each hydraulic actuator ML, MR, MT, C1 to C6.

[0064] The second relief valve V15 and the second unload valve V16 are connected to the drain oil passage g.

[0065] The first pressurized oil supply passage d and the second pressurized oil supply passage e are connected to each other within the inlet block B2 via a connecting passage j that crosses the travel independent valve V14.

[0066] The travel-independent valve V14 is switchable between an independent position 27 that shuts off the flow of pressurized oil through the communication passage j and a merging position 28 that allows the flow of pressurized oil through the communication passage j.

[0067] When the travel independent valve V14 is switched to the independent position 27, hydraulic fluid from the first pressurized oil discharge port P1 can be supplied to the directional control valves DV4 and DV3 of the second travel control valve V4 and the first control valve V3 for the dozer, respectively, and hydraulic fluid from the second pressurized oil discharge port P2 can be supplied to the directional control valves DV5 and DV6 of the first travel control valve V5 and the second control valve V6 for the dozer, respectively, but hydraulic fluid from the first pressurized oil discharge port P1 is not supplied to the first travel control valve V5 and the second control valve V6 for the dozer, and hydraulic fluid from the second pressurized oil discharge port P2 is not supplied to the second travel control valve V4 and the first control valve V3 for the dozer.

[0068] Furthermore, when the travel-independent valve V14 is switched to the confluence position 28, the hydraulic fluid from the first pressurized oil discharge port P1 and the hydraulic fluid from the second pressurized oil discharge port P2 are combined and made available for supply to the directional control valves DV1 to DV10 of each of the control valves V1 to V10.

[0069] The third pressurized oil discharge port P3 is connected to the inlet block B2 via the third discharge passage m, which branches into a first branched oil passage m1 and a second branched oil passage m2, both of which are connected to the inlet block B2.

[0070] The first branch oil passage m1 is connected to the pressure receiving section 14a on one side of the travel-independent valve V14 via the first signal oil passage n1, and the second branch oil passage m2 is connected to the pressure receiving section 14b on the other side of the travel-independent valve V14 via the second signal oil passage n2.

[0071] The first signal oil passage n1 is connected to the first detection oil passage r1, and the second signal oil passage n2 is connected to the second detection oil passage r2.

[0072] The first detection oil passage r1 is connected to the drain oil passage g via the first signal oil passage n1, the directional control valve DV6 of the second control valve V6 for the dozer, the directional control valve DV5 of the first travel control valve V5, the directional control valve DV4 of the second travel control valve V4, and the directional control valve DV3 of the first control valve V3 for the dozer.

[0073] The second detection oil passage r2 is connected to the drain oil passage g via the second signal oil passage n2, the directional control valve DV10 of the SP control valve V10 → the directional control valve DV9 of the swing control valve V9 → the directional control valve DV8 of the slewing control valve V8 → the directional control valve DV7 of the arm control valve V7 → the directional control valve DV6 of the second control valve V6 for the dozer → the directional control valve DV5 of the first travel control valve V5 → the directional control valve DV4 of the second travel control valve V4 → the directional control valve DV3 of the first control valve V3 for the dozer → the directional control valve DV2 of the boom control valve V2 → the directional control valve DV1 of the bucket control valve V1.

[0074] The aforementioned independent travel valve V14 is held in the merging position 28 by spring force when the directional control valves DV1 to DV10 of each control valve V1 to V10 are in the neutral position.

[0075] Then, when any of the directional control valves DV, such as the second travel control valve V4, the first travel control valve V5, the first control valve V3 for the dozer, or the second control valve V6 for the dozer, are operated from the neutral position, pressure is built up in the first detection oil passage r1 and the first signal oil passage n1, and the independent travel valve V14 is switched from the merging position 28 to the independent position 27.

[0076] Therefore, when only driving is performed, when the dozer device 7 is used while driving, or when only the dozer device 7 is used, the hydraulic fluid from the first pressurized oil discharge port P1 is supplied to the directional control valves DV of the second driving control valve V4 and the first control valve V3 for the dozer, and the hydraulic fluid from the second pressurized oil discharge port P2 is supplied to the directional control valves DV of the first driving control valve V5 and the first control valve V3 for the dozer.

[0077] At this time, when any of the directional control valves DV10, DV9, DV8, DV7, DV2, or DV1 of the SP control valve V10, swing control valve V9, slewing control valve V8, arm control valve V7, boom control valve V2, or bucket control valve V1 are operated from the neutral position, pressure is built up in the second detection oil passage r2 and the second signal oil passage n2, and the travel independent valve V14 is switched from the independent position 27 to the merging position 28.

[0078] Furthermore, when the directional control valves DV1 to DV10 of each control valve V1 to V10 are in the neutral position, the independent travel valve V14 is also in the merging position 28 when any of the directional control valves DV10, DV9, DV8, DV7, DV2, or DV1 of the SP control valve V10, swing control valve V9, slewing control valve V8, arm control valve V7, boom control valve V2, or bucket control valve V1 is operated from the neutral position.

[0079] Therefore, simultaneous operation of the boom 15, arm 16, bucket 17, swing bracket 14, machine body 2, and dozer device 7 is possible, whether the machine is not moving or is moving.

[0080] Furthermore, this hydraulic system is equipped with an automatic idling control system (AI system) that automatically operates the accelerator device of the prime mover E1.

[0081] This AI system includes an AI switch (pressure switch) 29 connected to the first branch oil passage m1 and the second branch oil passage m2 of the third discharge passage m via a sensing oil passage s and a shuttle valve V18, an electric actuator that controls the governor of the prime mover E1, and a control device that controls the electric actuator, the AI ​​switch 29 being connected to the control device.

[0082] In this AI system, when the directional control valves DV1 to DV10 of each control valve V1 to V10 are in the neutral position, no pressure is built up in the first branch oil passage m1 and the second branch oil passage m2. Therefore, the AI ​​switch 29 does not activate due to pressure. In this state, the governor is automatically controlled by an electric actuator or the like to reduce the accelerator to a preset idling position.

[0083] Furthermore, if any one of the directional control valves DV1 to DV10 of the control valves V1 to V10 is operated, pressure will be generated in the first branch oil passage m1 or the second branch oil passage m2. This pressure is detected by the AI ​​switch 29, which then activates. In response, the control device sends a command signal to an electric actuator, etc., which then automatically controls the governor to accelerate up to the set accelerator position.

[0084] Furthermore, this hydraulic system employs a load sensing system.

[0085] The load sensing system of this embodiment includes pressure compensation valves V11 provided on each control valve V1 to V10, a flow rate compensation piston 24 that controls the swash plate of the first pump 21, a flow rate compensation valve V17 equipped on the flow rate control unit 19, the first and second relief valves V12 and V15, and the first and second unload valves V13 and V16. Furthermore, the load sensing system of this embodiment employs an after-orifice type load sensing system in which the pressure compensation valve V11 is positioned on the downstream side of the pressurized oil supply to the directional control valves DV1 to DV10.

[0086] In this load sensing system, when multiple hydraulic actuators ML, MR, MT, C1 to C6 equipped on the work machine 1 are operated simultaneously, the pressure compensation valve V11 functions to adjust the load between the hydraulic actuators ML, MR, MT, C1 to C6, generating a pressure loss equal to the pressure difference between the low-load pressure and the maximum load pressure in the control valves V1 to V10 on the low-load pressure side. This allows the flow rate to be distributed according to the amount of spool operation of the directional control valves DV1 to DV10, regardless of the load size. In other words, the load sensing system controls the first pump 21 so that the pressure difference obtained by subtracting the maximum load pressure among the multiple hydraulic actuators ML, MR, MT, C1 to C6 from the discharge pressure of the first pump 21 is kept constant.

[0087] Furthermore, the load sensing system controls the discharge amount of the first pump 21 according to the load pressure of each hydraulic actuator ML, MR, MT, C1 to C6 equipped on the work machine 1, thereby discharging the hydraulic power required for the load from the first pump 21, and thus saving power and improving operability.

[0088] The load sensing system of this embodiment will be described in more detail.

[0089] The load sensing system includes a PLS signal oil passage w that transmits the highest load pressure among the load pressures of each control valve V1 to V10 as a PLS signal pressure to the flow compensation valve V17, and a PPS signal oil passage x that transmits the discharge pressure of the first pump 21 as a PPS signal pressure to the flow compensation valve V17.

[0090] The PLS signal oil passage w is provided from the first outlet block B1 through the valve body of the bucket control valve V1 → the valve body of the boom control valve V2 → the valve body of the first control valve V3 for the dozer → the valve body of the second travel control valve V4, and also crosses the travel independent valve V14 and is provided through the valve body of the first travel control valve V5 → the valve body of the second control valve V6 for the dozer → the valve body of the arm control valve V7 → the valve body of the slewing control valve V8 → the valve body of the swing control valve V9 → the valve body of the SP control valve V10 → the second outlet block B3, and the PLS signal oil passage w is connected to the pressure compensation valve V11 in each control valve via a load transmission line y.

[0091] Furthermore, this PLS signal oil passage w is connected from the second outlet block B3 to one side of the spool of the flow compensation valve V17, and the PPS signal pressure acts on one side of the spool of the flow compensation valve V17.

[0092] Furthermore, the PLS signal oil passage w is connected to the first unload valve V13 and the drain oil passage g in the first outlet block B1, and to the second unload valve V16 and the drain oil passage g in the second outlet block B3.

[0093] When the independent travel valve V14 is in the merging position 28, the line w1 of the PLS signal oil passage w from the independent travel valve V14 to the first outlet block B1 and the line w2 of the independent travel valve V14 to the second outlet block B3 are in communication. When the independent travel valve V14 is switched from the merging position 28 to the independent position 27, the PLS signal oil passage w is shut off by the independent travel valve V14.

[0094] As a result, when the travel independent valve V14 is set to the independent position 27, the PLS signal oil passage w is divided into line w1 on the side to which hydraulic fluid is supplied from the first pressurized oil discharge port P1 and line w2 on the side to which pressurized oil is supplied from the second pressurized oil discharge port P2.

[0095] The PPS signal oil passage x is provided from the travel-independent valve V14 to the other side of the spool of the flow compensation valve V17. When the travel-independent valve V14 is in the merging position 28, the PPS signal oil passage x is connected to the second pressurized oil supply passage e via a connecting oil passage z, and the PPS signal pressure (discharge pressure of the first pump 21) acts on the other side of the spool of the flow compensation valve V17. When the travel-independent valve V14 is switched to the independent position 27, the PPS signal oil passage x is connected to the drain oil passage g via a relief oil passage q, and the PPS signal pressure is set to zero.

[0096] Furthermore, a spring 30 and a differential pressure piston 31 are provided on one side of the spool of the flow compensation valve V17 to apply a control differential pressure to the flow compensation valve V17.

[0097] In the hydraulic system with the above configuration, when the directional control valves DV1 to DV10 of each control valve V1 to V10 are in the neutral position, the travel independent valve V14 is in the confluence position 28. At this time, the end of the flow path of the first pressurized oil supply passage d is blocked by the first unload valve V13, and the end of the flow path of the second pressurized oil supply passage e is blocked by the second unload valve V16. Therefore, when the discharge pressure (PPS signal pressure) of the first pump 21 rises, and the difference between this PPS signal pressure and the PLS signal pressure (which is zero at this time) becomes greater than the control differential pressure, the flow rate of the first pump 21 is controlled to decrease the discharge amount, and the first and second unload valves V16 open, allowing the discharged oil from the first pump 21 to fall into the hydraulic oil tank T2.

[0098] Therefore, in this state, the discharge pressure of the first pump 21 becomes the pressure set by the first and second unload valves V13 and V16, and the discharge flow rate of the first pump 21 becomes the minimum discharge rate.

[0099] Next, we will explain the case where two or more of the boom cylinder C3, arm cylinder C4, bucket cylinder C5, swing cylinder C2, slewing motor MT, and hydraulic attachment are operated simultaneously, or the case where one or more of these are operated simultaneously with one or more of the left / right travel motors ML, MR, and dozer cylinder C1.

[0100] In this case, the travel-independent valve V14 is at the merging position 28, and the maximum load pressure acting on the operated hydraulic actuators ML, MR, MT, C1 to C6 becomes the PLS signal pressure. The discharge pressure (discharge flow rate) of the first pump 21 is automatically controlled so that the difference between the PPS signal pressure and the PLS signal pressure becomes the control differential pressure (maintaining the difference between the PPS signal pressure and the PLS signal pressure at a set value).

[0101] In other words, when the unload flow rate through the first and second unload valves V13 and V16 becomes zero, the discharge flow rate of the first pump 21 begins to increase, and the entire amount of oil discharged from the first pump 21 flows to the operated hydraulic actuators ML, MR, MT, C1 to C6 according to the amount of operation of the operated control valve.

[0102] Furthermore, the pressure compensation valve V11 ensures that the differential pressure across the spools of the directional control valves DV1 to DV10 of the operated control valves V1 to V10 remains constant. Regardless of the difference in the magnitude of the load acting on the operated hydraulic actuators ML, MR, MT, C1 to C6, the discharge flow rate of the first pump 21 is divided among the operated hydraulic actuators ML, MR, MT, C1 to C6 by an amount corresponding to the amount of operation.

[0103] Furthermore, if the required flow rates of the hydraulic actuators ML, MR, MT, and C1-C6 exceed the maximum discharge flow rate of the first pump 21, the discharged oil from the first pump 21 is distributed proportionally to each operated hydraulic actuator ML, MR, MT, and C1-C6.

[0104] In the aforementioned case, simultaneous operation (complex operation) becomes possible with an efficient system.

[0105] When earthwork is performed by the bulldozer device 7 while the machine is moving, the travel independent valve V14 is switched to the independent position 27, and the travel independent valve V14 blocks the communication passage j and the PLS signal oil passage w, and the PPS signal oil passage x is connected to the drain oil passage g via the relief oil passage q, and the PPS signal pressure becomes zero.

[0106] Therefore, the hydraulic fluid from the first pressurized oil discharge port P1 flows to the second travel control valve V4 and the first control valve V3 for the dozer, but does not flow to the first travel control valve V5 and the second control valve V6 for the dozer. Also, the hydraulic fluid from the second pressurized oil discharge port P2 flows to the first travel control valve V5 and the second control valve V6 for the dozer, but does not flow to the second travel control valve V4 and the first control valve V3 for the dozer. Furthermore, since the PPS signal pressure is zero, the first pump 21 discharges at its maximum flow rate with its swash plate angle at MAX.

[0107] As shown in Figure 8, the proportional solenoids so1 to so10 of each directional control valve DV1 to DV10 are connected to the control device U1. Each directional control valve DV1 to DV10 (each control valve V1 to V10) is pilot-operated by a pilot control pressure corresponding to a control signal (current value supplied to the proportional solenoids so1 to so10) transmitted from the control device U1 to the proportional solenoids so1 to so10, so that the direction and flow rate of the hydraulic fluid to the hydraulic actuators ML, MR, MT, C1 to C6 are controlled. In other words, each control valve V1 to V10 is pilot-operated by a pilot control pressure controlled by a control signal transmitted from the control device U1. To put it another way, each control valve V1 to V10 is electronically controlled according to the current value supplied by the control device U1.

[0108] The control device U1 is connected to operating members 41 (first operating tool 41A to seventh operating tool 41G) that operate each directional control valve DV1 to DV10 (each control valve V1 to V10). The control device U1 detects when an operating member 41 is operated and supplies (transmits) a current value (control signal) corresponding to the amount of operation of the operating member 41 to the proportional solenoids so1 to so10 of the directional control valves DV1 to DV10 that are being operated.

[0109] The first operating device 41A and the second operating device 41B are provided on the control device 1B and consist of handles that are grasped and operated by an operator seated in the driver's seat 6, for example.

[0110] The first operating tool 41A can operate two operating objects equipped on the work machine 1. For example, the first operating tool 41A can operate the directional control valve DV8 (swing motor MT) (allowing the machine body 2 to be swung) and the directional control valve DV7 (arm cylinder C4) (allowing the arm 16 to swing).

[0111] Furthermore, the first operating tool 41A has a sensor (operation detection unit) 42 (first sensor 42A) that detects the operating direction and amount of operation. The first sensor 42A is connected to the control device U1. The control device U1 acquires the operating direction and amount of operation of the first operating tool 41A from the detection signal from the first sensor 42A, and controls the slewing control valve V8 (machine body 2) and the arm control valve V7 (arm 16) based on the detection signal from the first sensor 42A.

[0112] The second operating tool 41B can also operate two controllable objects equipped on the work machine 1. For example, the second operating tool 41B can operate the directional control valve DV2 (boom cylinder C3) (allowing the boom 15 to swing) and the directional control valve DV1 (bucket cylinder C5) (allowing the bucket 17 to swing).

[0113] Furthermore, the second operating tool 41B has a sensor (operation detection unit) 42 (second sensor 42B) that detects the operating direction and amount of operation. The second sensor 42B is connected to the control device U1. The control device U1 acquires the operating direction and amount of operation of the second operating tool 41B from the detection signal from the second sensor 42B, and controls the boom control valve V2 (boom 15) and the bucket control valve V1 (bucket 17) based on the detection signal from the second sensor 42B.

[0114] The third operating device 41C is provided on the control device 1B and is, for example, configured as a lever. The third operating device 41C can operate the directional control valves DV3 and DV6 (dozer cylinder C1) (it can operate the dozer device 7). The third operating device 41C also has a sensor 42 (third sensor 42C) that detects the direction and amount of operation. The third sensor 42C is connected to the control device U1. The control device U1 acquires the direction and amount of operation of the third operating device 41C from the detection signal from the third sensor 42C, and controls the first control valve V3 and the second control valve V6 for the dozer (dozer device 7) based on the detection signal from the third sensor 42C.

[0115] The fourth operating device 41D and the fifth operating device 41E are, for example, pedals provided on the floor in front of the driver's seat 6 and operated by the operator stepping on them.

[0116] The fourth operating tool 41D is capable of operating the directional control valve DV5 (first travel motor ML) (operating the first travel device 3L). The fourth operating tool 41D also has a sensor 42 (fourth sensor 42D) that detects the operating direction and amount. The fourth sensor 42D is connected to the control device U1. The control device U1 acquires the operating direction and amount of the fourth operating tool 41D from the detection signal from the fourth sensor 42D, and controls the first travel control valve V5 (first travel device 3L) based on the detection signal from the fourth sensor 42D.

[0117] The fifth operating tool 41E is capable of operating the directional control valve DV4 (second travel motor MR) (and thus the second travel device 3R). The fifth operating tool 41E also has a sensor 42 (fifth sensor 42E) that detects the direction and amount of operation. The fifth sensor 42E is connected to the control device U1. The control device U1 acquires the direction and amount of operation of the fifth operating tool 41E from the detection signal from the fifth sensor 42E, and controls the second travel control valve V4 (second travel device 3R) based on the detection signal from the fifth sensor 42E.

[0118] The sixth operating device 41F is composed of, for example, a switch (seesaw switch, slide switch, etc.) provided on the first operating device 41A or the second operating device 41B. The sixth operating device 41F can operate the directional control valve DV9 (swing cylinder C2) (it can operate the swing bracket 14). The sixth operating device 41F also has a sensor 42 (sixth sensor 42F) that detects the operating direction and amount. The sixth sensor 42F is connected to the control device U1. The control device U1 acquires the operating direction and amount of the sixth operating device 41F from the detection signal from the sixth sensor 42F, and controls the swing control valve V9 (swing bracket 14) based on the detection signal from the sixth sensor 42F.

[0119] The seventh operating tool 41G is composed of, for example, a switch (seesaw switch, slide switch, etc.) provided on the first operating tool 41A or the second operating tool 41B. The seventh operating tool 41G can operate the directional control valve DV10 (hydraulic actuator of the hydraulic attachment) (it can operate the hydraulic attachment as a work tool). The seventh operating tool 41G also has a sensor 42 (seventh sensor 42G) that detects the operating direction and amount. The seventh sensor 42G is connected to the control device U1. The control device U1 acquires the operating direction and amount of the seventh operating tool 41G from the detection signal from the seventh sensor 42G, and controls the SP control valve V10 (hydraulic attachment) based on the detection signal from the seventh sensor 42G.

[0120] The configuration of the sensors 42 (first sensors 42A to seventh sensors 42G) is not particularly limited, but for example, potentiometers can be used.

[0121] The spools of each directional control valve DV1 to DV10 are moved according to the amount of operation of each operating member 41 that operates each directional control valve DV1 to DV10 (each control valve V1 to V10), and the amount of hydraulic fluid corresponding to the amount that each directional control valve DV1 to DV10 is moved is supplied to the controlled hydraulic actuators ML, MR, MT, C1 to C6. In other words, the operating speed of the controlled object can be changed according to the amount of operation of each operating member 41.

[0122] As described above, the control valves V1 to V10 are operated by the operation of the operating member 41, and the corresponding hydraulic actuators ML, MR, MT, C1 to C6 are operated as a result. The hydraulic actuators ML, MR, MT, C1 to C6 then drive the drive parts (machine body 2, traveling device 3, dozer device 7, boom 15, arm 16, bucket 17, hydraulic attachment).

[0123] Incidentally, setting the operating speed of the bucket 17 to a faster speed is advantageous in that it makes it easier to operate. However, setting the operating speed of the bucket 17 to be too fast can cause problems. For example, when excavation work is being performed with the bucket 17, a load is acting on the bucket 17 when it is digging soil, and when the bucket 17 is pulled out of the ground, some of the load acting on the bucket 17 is released, which can cause the oscillating motion of the bucket 17 to suddenly become faster. Taking such cases into consideration, the operating speed of the bucket 17 is set to be somewhat restrained (for example, to a speed that the operator perceives as slightly slow).

[0124] Furthermore, the bucket 17 may be operated simultaneously with the arm 16 (combined operation). Since the arm cylinder C4 is a section where flow rate is required, when the bucket 17 and arm 16 are operated in combination, horsepower limitations may be imposed, resulting in a decrease in the operating speed of both the bucket 17 and the arm 16. Because the bucket 17 is originally set to operate at a slow speed, when the bucket 17 and arm 16 are operated in combination, the operating speed of the bucket 17 becomes slower than when the bucket 17 is operated alone, which tends to make the operator feel dissatisfied with the operating speed of the bucket 17. The same can be said for other work tools besides the bucket 17.

[0125] Furthermore, in the case of a large class of work machine 1, the length of the bucket 17 (for example, the distance from the pivot 61 to the tip 62a of the claw portion 62 of the bucket 17) is relatively small compared to the length of the arm 16, so moving the arm 16 allows for a greater movement distance of the tip 62a of the bucket 17 than moving the bucket 17.

[0126] In contrast, in the case of the small class of work machine 1, although the length of the arm 16 is smaller than that of the large class of work machine 1, the size of the bucket 17 cannot be made much smaller, so the length of the bucket 17 does not change much. Therefore, in the small class of work machine 1, moving the bucket 17 allows for a greater travel distance of the bucket's claws 62a than moving the arm 16. In other words, when considering the movement of the bucket's claws 62a, in the case of the small class of work machine 1, prioritizing the movement of the bucket 17 over the movement of the arm 16 allows for the construction of a machine that moves more nimbly.

[0127] Therefore, in the work machine 1 of this embodiment, when the bucket (work tool) 17 and the arm 16 are operated in combination, the operation of the arm control valve V7 is controlled (proportional control) according to the amount of operation of the operating member 41, so as to reduce the change in the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 in response to the change in the amount of operation of the operating member 41, compared to when the arm cylinder C4 is operated alone (the arm 16 is operated alone) with the same amount of operation of the operating member 41 (first operating tool 41A) as when the arm cylinder C4 is operated in combination.

[0128] The operation of the arm control valve V7 is controlled by the control device U1. Specifically, when the bucket (working tool) 17 and the arm 16 are operated in combination, the control device U1 detects that the arm 16 has been operated based on the detection signal from the first sensor 42A and that the bucket 17 has been operated based on the detection signal from the second sensor 42B, thereby determining that the bucket 17 and the arm 16 have been operated in combination. When the bucket 17 and the arm 16 are operated in combination, the control device U1 sends a control signal to the arm control valve V7 to lower the pilot control pressure of the arm control valve V7 compared to when the arm 16 is operated alone. As a result, the spool stroke of the arm control valve V7 is reduced, and the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 is reduced. This makes it possible to suppress the reduction in the flow rate of hydraulic fluid supplied from the bucket control valve V1 to the bucket cylinder C5.

[0129] Therefore, the operating speed of the bucket (working tool) 17 can be ensured when the bucket 17 and arm 16 are operated in combination. In other words, when the bucket 17 and arm 16 are operated in combination, the control device U1 reduces the flow rate of the hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4, thereby suppressing the decrease in the operating speed of the bucket 17 when the bucket 17 and arm 16 are operated in combination, and consequently, the bucket 17 can be operated appropriately when the bucket 17 and arm 16 are operated in combination.

[0130] Furthermore, in the work machine 1 of this embodiment, when the bucket 17 and arm 16 are operated in combination, the control device U1 reduces the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4. Therefore, reducing the flow rate of hydraulic fluid supplied to the arm cylinder C4 (reducing the output of the arm control valve V7) only requires a program setting in the control device U1, eliminating the need to install new valves or oil passages in the system, thus reducing costs and allowing the system to be provided at a low price. In addition, the hydraulic system in this embodiment employs a load sensing system. In the load sensing system, the flow rate of hydraulic fluid output from each control valve is stably controlled by the amount of movement of the control valve's spool (pilot control pressure), regardless of the load pressure acting on the controlled object. Therefore, it is easy to control the reduction of the output of the arm control valve V7 when the bucket 17 and arm 16 are operated in combination.

[0131] Furthermore, if the work machine 1 in this embodiment is a small work machine 1, when the bucket 17 and arm 16 are operated in combination, the control device U1 is configured to reduce the flow rate of the hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4. This makes it possible to construct a work machine 1 that moves quickly, considering the movement of the tip 62a of the bucket 17.

[0132] As shown in Figure 8, the first operating tool 41A (operating member 41) is a member capable of operating the arm control valve V7, the arm cylinder C4, and the arm 16. In other words, when the first operating tool 41A is operated to operate the arm control valve V7, etc., a detection signal from the first sensor 42A is transmitted to the control device U1. Upon receiving the detection signal from the first sensor 42A, the control device U1 transmits a control signal to the arm control valve V7. Upon receiving the control signal, the arm control valve V7 operates to output hydraulic fluid to the arm cylinder C4, and the arm cylinder C4 is operated by the hydraulic fluid from the arm control valve V7 to drive the arm 16.

[0133] Therefore, the first operating tool 41A (operating member 41) is a member that operates the arm control valve V7, a member that operates the arm cylinder C4, and a member that operates the arm 16.

[0134] Next, a system for controlling the arm 16 (arm cylinder C4, arm control valve V7) will be described based on Figure 8.

[0135] As shown in Figure 8, the control device U1 includes a control unit Ua and an arm flow rate suppression unit Ub.

[0136] The control unit Ua controls the operation of the arm control valve V7 (proportional control) when the arm 16 (arm cylinder C4, arm control valve V7) is operated independently. In other words, when the arm 16 is operated independently, the control unit Ua controls the flow rate of the hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4.

[0137] The arm flow rate suppression unit Ub controls the operation of the arm control valve V7 (proportional control) when the bucket (working tool) 17 and the arm 16 are operated in combination. In other words, the arm flow rate suppression unit Ub controls the flow rate of the hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 when the bucket 17 and the arm 16 are operated in combination.

[0138] Figure 9 is a graph showing the relationship between the amount of operation of the operating member 41 (first operating tool 41A) and the flow rate of the hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4, with the horizontal axis representing the amount of operation of the operating member 41 (first operating tool 41A) and the vertical axis representing the flow rate of the hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4.

[0139] In Figure 9, the first line 50 shows a case where the control unit Ua controls the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 in relation to the amount of operation of the operating member 41.

[0140] The second line 51 in Figure 9 shows a case where the arm flow rate suppression unit Ub controls the flow rate of the hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 in relation to the amount of operation of the operating member 41.

[0141] As can be seen from the first line 50 and the second line 51 in Figure 9, when the amount of operation of the operating member 41 (first operating tool 41A) is the same as when the arm 16 (arm cylinder C4, arm control valve V7) is operated alone, the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 is less when the bucket 17 and arm 16 are operated together compared to when the arm cylinder C4 (arm control valve V7) is operated alone. In other words, when the bucket 17 and arm 16 are operated together, the flow rate of hydraulic fluid supplied to the arm cylinder C4 in relation to the amount of operation of the operating member 41 (first operating tool 41A) decreases.

[0142] In other words, the arm flow rate suppression unit Ub causes the arm control valve V7 to supply a flow rate of hydraulic fluid to the arm cylinder C4 that is less than the flow rate of hydraulic fluid controlled by the control unit Ua for the same amount of operation of the operating member 41. Therefore, when the bucket 17 and arm 16 are operated in combination, the arm flow rate suppression unit Ub reduces the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4. To put it another way, the arm flow rate suppression unit Ub causes the arm control valve V7 to supply a flow rate of hydraulic fluid to the arm cylinder C4 that is less than the flow rate of hydraulic fluid controlled by the control unit Ua for the amount of operation of the operating member 41 (first operating tool 41A). This suppresses the decrease in the flow rate of hydraulic fluid output from the bucket control valve V1 when the bucket 17 and arm 16 are operated in combination, and ensures the operating speed of the bucket 17.

[0143] In this embodiment, the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 is reduced by lowering the pilot control pressure, which is controlled by a control signal transmitted from the control device U1 to the arm control valve V7. In other words, the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 is reduced by lowering the current value supplied by the control device U1 to the arm control valve V7.

[0144] Next, based on Figure 10, the pilot control pressure (pilot output) applied to the bucket control valve V1 and the arm control valve V7 when the bucket 17 and the arm 16 are operated individually and when they are operated in combination will be explained.

[0145] As shown in Figure 10, when the pilot control pressure applied to the bucket control valve V1 is set to 100% when the bucket 17 is operated alone, the pilot control pressure applied to the bucket control valve V1 when the bucket 17 and arm 16 are operated in combination is also 100%.

[0146] On the other hand, when the pilot control pressure applied to the arm control valve V7 when the arm 16 is operated alone is set to 100%, the pilot control pressure applied to the arm control valve V7 when the bucket 17 and arm 16 are operated together is 70%. In other words, when the bucket 17 and arm 16 are operated together, the pilot control pressure is reduced to 70% compared to the 100% pilot control pressure when the arm 16 is operated alone to control the arm control valve V7. When the bucket 17 and arm 16 are operated together, the pilot control pressure is reduced compared to when the arm 16 is operated alone to control the arm control valve V7, thereby reducing the output of the arm control valve V7 and ensuring the flow rate of the hydraulic fluid output from the bucket control valve V1.

[0147] Furthermore, the pilot control pressure (70%) when the bucket 17 and arm 16 are operated in combination is not limited to the values ​​shown in Figure 10, as opposed to the pilot control pressure (100%) when the arm 16 is operated alone.

[0148] Furthermore, the extent to which the pilot control pressure when the bucket 17 and arm 16 are operated in combination (referred to as the combined operation control pressure) is reduced relative to the pilot control pressure when the arm 16 is operated alone (referred to as the control pressure when the arm 16 is operated alone) may be freely adjustable. In other words, the ratio of the control pressure when the arm 16 is operated alone to the control pressure when the combined operation is operated may be freely adjustable so that the combined operation control pressure is lower than the control pressure when the arm 16 is operated alone.

[0149] The setting change that reduces the pilot control pressure when the bucket 17 and arm 16 are operated in combination may be made stepwise or continuously. If the setting can be changed stepwise, it may be possible to change the setting in two or three or more steps.

[0150] By allowing the setting of the control pressure during combined operation to be changed, for example, the control pressure during combined operation can be set for each size (class) of the work implement 1. For example, the control pressure during combined operation can be set to a higher value for large class work implements 1 and to a lower value for small class work implements 1 than for large class work implements 1. In this way, by making the control pressure during combined operation freely adjustable for each size of the work implement 1, it is possible to optimize the ratio between the pilot control pressure during arm-only operation and the pilot control pressure during bucket-arm combined operation (the ratio of the pilot control pressure during arm-only operation to the pilot control pressure during bucket-arm combined operation, when the pilot control pressure during combined operation is changed relative to the pilot control pressure during single operation) for each class of work implement 1, in order to construct a work implement 1 equipped with a bucket 17 as a work tool, such as a work implement 1 in which the claws 62a of the bucket 17 move smoothly.

[0151] The setting of the control pressure during the combined operation described above may be changed by changing the program of the control device U1, but as shown in Figure 8, the setting of the control pressure during the combined operation may also be done by a setting switch 63 connected to the control device U1. The setting switch 63 is a switch operated manually by the operator and consists of, for example, a rotary switch, a push button switch, a switch on a touch panel, etc. In Figure 8, the setting switch 63 is shown to be connected to the control device U1 by a connection line, but the setting switch 63 may also be connected to the control device U1 wirelessly.

[0152] When the combined operation control pressure is set using the setting switch 63, the control device U1 acquires the operation signal transmitted from the setting switch 63, and the combined operation control pressure selected by the setting switch 63 is set (stored) in the arm flow rate suppression unit Ub. When the bucket 17 and arm 16 are operated in combination, the arm flow rate suppression unit Ub transmits a control signal to the arm control valve V7 so that the pilot control pressure is applied to the arm control valve V7 at the set combined operation control pressure.

[0153] In the above hydraulic system, each control valve V1 to V10 (each directional control valve DV1 to DV10) is configured as a pilot-operated proportional solenoid valve, and the control device U1 controls the pilot control pressure by controlling the current value supplied to each control valve V1 to V10, thereby controlling each control valve V1 to V10. However, the system is not limited to this configuration.

[0154] For example, as shown in Figure 11, each control valve V1 to V10 may be configured as a pilot-operated switching valve that is pilot-operated by pilot control pressure acting on a pair of pilot pressure receiving sections Va1 and Va2, and a pair of proportional solenoid valves V21 and V22 controlled by a control device U1 may be provided, with pilot control pressure supplied from one proportional solenoid valve V21 to one pilot pressure receiving section Va1, and pilot control pressure supplied from the other proportional solenoid valve V22 to the other pilot pressure receiving section Va2, thereby controlling the direction and flow rate of the hydraulic fluid to the hydraulic actuators MT, ML, MR, C1 to C6.

[0155] Alternatively, as shown in Figure 12, each control valve V1 to V10 may be configured as a proportional electromagnetic directional and flow control valve in which the spool is directly driven by a proportional solenoid so11 supplied with current from the control device U1.

[0156] Therefore, in this case, the arm control valve V7 is not a valve controlled by pilot control pressure, but rather a valve that is directly controlled (proportionally controlled) by the current value supplied by the control device U1. Furthermore, when the bucket (working tool) 17 and the arm 16 are operated in combination, the control device U1 controls the operation of the arm control valve V7 by lowering the current value compared to when the arm cylinder C4 is operated alone, using the same amount of operation as the operating member 41 (first operating tool 41A) for the arm cylinder C4 in the case of combined operation.

[0157] Furthermore, even in this case, the degree to which the current value when the bucket (working tool) 17 and arm 16 are operated in combination is reduced compared to the current value when the arm 16 is operated alone may be freely adjustable. The other configurations are the same as in the above embodiment.

[0158] Furthermore, the work machine 1 in the above embodiment may be configured to allow selection of two modes: one in which the operation of the arm control valve V7 is controlled according to the amount of operation of the operating member 41 so as to reduce the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 when the bucket (work tool) 17 and the arm 16 are operated in combination; and another in which the operation of the arm control valve V7 is controlled according to the amount of operation of the operating member 41 without reducing the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 when the bucket 17 and the arm 16 are operated in combination. In this case, the selection (switching) of modes may be performed by a mode selection switch operated manually by the operator.

[0159] A preferred embodiment of the present invention provides a work machine 1 as described in the following items.

[0160] (Item 1) A work machine 1 comprising: a work tool cylinder C5 and an arm cylinder C4 driven by hydraulic fluid; a work tool 17 oscillated by the work tool cylinder C5; an arm 16 oscillated by the arm cylinder C4; an operating member 41 for operating the arm cylinder C4; an arm control valve V7 for changing the flow rate of hydraulic fluid supplied to the arm cylinder C4; and a control device U1 for controlling the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 by controlling the operation of the arm control valve V7 according to the amount of operation of the operating member 41, wherein when the work tool 17 and the arm 16 are operated in combination, the control device U1 controls the operation of the arm control valve V7 according to the amount of operation of the operating member 41 to reduce the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4 compared to when the arm cylinder C4 is operated alone with the same amount of operation as the operating member 41 for the arm cylinder C4 in the combined operation.

[0161] According to the work machine 1 related to item 1, it is possible to ensure the operating speed of the work tool 17 when the work tool 17 and the arm 16 are operated in combination.

[0162] (Item 2) The work machine 1 according to Item 1, wherein the arm control valve V7 is a valve pilot operated by a pilot control pressure controlled by a control signal transmitted from the control device U1, and the control device U1 lowers the pilot control pressure when the work tool 17 and the arm 16 are operated in combination, by the same amount of operation as the amount of operation of the operating member 41 on the arm cylinder C4 in the case of the combined operation, compared to when the arm cylinder C4 is operated alone.

[0163] According to the work machine 1 related to item 2, the operation of the arm control valve V7 when the work tool 17 and the arm 16 are operated in combination is controlled by a pilot control pressure controlled by a control signal transmitted from the control device U1. Therefore, to reduce the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4, only the program setting of the control device U1 is required, eliminating the need to install new valves or oil passages, thus reducing costs and allowing the machine to be provided at a low price.

[0164] (Item 3) The extent to which the pilot control pressure is reduced when the work tool 17 and the arm 16 are operated in combination is adjustable compared to when the arm 16 is operated alone, as described in Item 2.

[0165] According to the work machine 1 related to item 3, the pilot control pressure when the work tool 17 and the arm 16 are operated in combination can be optimally set according to various conditions (for example, the size and weight of the work machine 1, or the operator's preference).

[0166] (Item 4) The work machine 1 according to Item 1, wherein the arm control valve V7 is composed of a valve that is controlled according to the current value supplied by the control device U1, and the control device U1 reduces the current value when the work tool 17 and the arm 16 are operated in combination, by the same amount of operation as the amount of operation of the operating member 41 on the arm cylinder C4 in the case of the combined operation, compared to when the arm cylinder C4 is operated alone.

[0167] According to the work machine 1 related to item 4, the operation of the arm control valve V7 when the work tool 17 and the arm 16 are operated in combination is controlled by the current value supplied by the control device U1. Therefore, to reduce the flow rate of hydraulic fluid supplied from the arm control valve V7 to the arm cylinder C4, only the program setting of the control device U1 is required, eliminating the need to install new valves or oil passages, thus reducing costs and allowing the machine to be provided at a low price.

[0168] (Item 5) The work machine according to Item 4, wherein the extent to which the current value when the work tool 17 and the arm 16 are operated in combination is reduced relative to the current value when the arm 16 is operated alone is adjustable.

[0169] According to the work machine 1 related to item 5, the current value when the work tool 17 and the arm 16 are operated in combination can be optimally set according to various conditions (for example, the size and weight of the work machine 1, or the operator's preference).

[0170] (Item 6) The work machine 1 according to any one of items 1 to 5, comprising: a variable displacement hydraulic pump 21 that discharges hydraulic fluid to operate a plurality of hydraulic actuators including the arm cylinder C4 and the work tool cylinder C5; and a load sensing system that controls the hydraulic pump so that the differential pressure obtained by subtracting the highest load pressure of the plurality of hydraulic actuators from the discharge pressure of the hydraulic pump 21 becomes a constant pressure.

[0171] According to the work machine 1 related to item 6, in a work machine 1 equipped with a load sensing system, it is possible to effectively ensure the operating speed of the work tool 17 when the work tool 17 and the arm 16 are operated in combination.

[0172] (Item 7) A program to cause a computer to execute the processing of the control device U1 in the work machine 1 described in any one of Items 1 to 6.

[0173] According to item 7, by having a computer run the program, it is possible to provide the work machine 1 that produces the above-mentioned excellent effects.

[0174] (Item 8) A recording medium on which the program described in Item 7 is recorded in a computer-readable format.

[0175] According to item 8, by having a computer read the program related to item 7 from the recording medium and execute it, the work machine 1 that achieves the above-mentioned excellent effects can be provided.

[0176] Although one embodiment of the present invention has been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended to be included.

[0177] 16 Arm 17 Work tool (bucket) 21 Hydraulic pump 41 Operating member (first operating tool 41A) C4 Arm cylinder C5 Work tool cylinder U1 Control device Ua Control unit Ub Arm flow rate suppression unit Uc First mode Ud Second mode V7 Arm control valve

Claims

1. A work machine comprising: a work tool cylinder and an arm cylinder driven by hydraulic fluid; a work tool oscillated by the work tool cylinder; an arm oscillated by the arm cylinder; an operating member for operating the arm cylinder; an arm control valve for changing the flow rate of hydraulic fluid supplied to the arm cylinder; and a control device for controlling the flow rate of hydraulic fluid supplied from the arm control valve to the arm cylinder by controlling the operation of the arm control valve according to the amount of operation of the operating member, wherein the control device controls the operation of the arm control valve according to the amount of operation of the operating member so that when the work tool and the arm are operated in combination, the flow rate of hydraulic fluid supplied from the arm control valve to the arm cylinder is reduced compared to when the arm cylinder is operated alone with the same amount of operation of the operating member as when the arm cylinder is operated in combination.

2. The work machine according to claim 1, wherein the arm control valve is a valve pilot-operated by a pilot control pressure controlled by a control signal transmitted from the control device, and the control device reduces the pilot control pressure when the work tool and the arm are operated in combination, by the same amount of operation as the amount of operation of the operating member on the arm cylinder in the case of the combined operation, compared to when the arm cylinder is operated alone.

3. The work machine according to claim 2, wherein the extent to which the pilot control pressure is reduced when the work tool and the arm are operated in combination is adjustable relative to the pilot control pressure when the arm is operated alone.

4. The work machine according to claim 1, wherein the arm control valve is composed of a valve controlled according to a current value supplied by the control device, and the control device reduces the current value when the work tool and the arm are operated in combination, by the same amount of operation as the amount of operation of the operating member on the arm cylinder in the case of the combined operation, compared to when the arm cylinder is operated alone.

5. The work machine according to claim 4, wherein the extent to which the current value is reduced when the work tool and the arm are operated in combination is adjustable compared to the current value when the arm is operated alone.

6. The work machine according to any one of claims 1 to 5, comprising: a variable displacement hydraulic pump that discharges hydraulic fluid to operate a plurality of hydraulic actuators including the arm cylinder and the work tool cylinder; and a load sensing system that controls the hydraulic pump so that the differential pressure obtained by subtracting the highest load pressure of the plurality of hydraulic actuators from the discharge pressure of the hydraulic pump becomes a constant pressure.

7. A program for causing a computer to perform the processing of the control device in the work machine according to any one of claims 1 to 5.

8. A recording medium in which the program described in claim 7 is recorded in a computer-readable format.

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