Work equipment

Abstract

To provide a work machine capable of suppressing a reduction in the travel speed when operating another hydraulic actuator other than a travel motor during travelling.SOLUTION: The work machine includes a machine body, a travel device supporting the machine body in a travelable manner, the travel motor constructed by a hydraulic motor to drive the travel device, another hydraulic actuator than the travel motor, an actuator control valve for controlling another hydraulic actuator, and a control device for controlling the actuator control valve, the control device having an actuator flow suppression part for reducing the flow amount of working oil to be supplied from the actuator control valve to another hydraulic actuator if operating another hydraulic actuator when driving the travel device.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a work machine such as a backhoe. [Background technology]

[0002] 2. Description of the Related Art A working machine disclosed in Patent Document 1 is known in the art. The working machine disclosed in Patent Document 1 has a traveling device that supports a machine body so that the machine body can travel. The traveling device is driven by a traveling motor formed by a hydraulic motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-79366 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a hydraulic actuator other than the traveling motor is operated while the vehicle is traveling, the flow rate of hydraulic oil supplied to the traveling motor is taken up by the other hydraulic actuator, causing a problem of a drop in traveling speed and a shock. In view of the above-mentioned problems, the present invention aims to provide a work machine that can suppress a decrease in traveling speed when a hydraulic actuator other than the traveling motor is operated while traveling. [Means for solving the problem]

[0005] A working machine according to one aspect of the present invention includes a machine body, a traveling device that supports the machine body so that it can travel, a traveling motor constituted by a hydraulic motor that drives the traveling device, another hydraulic actuator different from the traveling motor, an operating member that operates the other hydraulic actuator, an actuator control valve that changes a flow rate of hydraulic oil supplied to the other hydraulic actuator, and a control device that controls the operation of the actuator control valve in response to an operating amount of the operating member, The actuator control valve is a pilot-operated proportional solenoid valve that is pilot-operated by a pilot control pressure that is controlled by a control signal transmitted from the control device, The control device proportionally controls the operation of the actuator control valve in response to an amount of operation of the operating member when the other hydraulic actuator is operated alone without driving the travel motor. to the actuator control valve. By controlling the flow rate of the hydraulic oil supplied from the actuator control valve to the other hydraulic actuator, when the other hydraulic actuator is operated while the traveling device is being driven, the flow rate of the hydraulic oil supplied from the actuator control valve to the other hydraulic actuator is reduced to be lower than the flow rate of the hydraulic oil supplied to the other hydraulic actuator when the other hydraulic actuator is operated alone with the same operation amount. and The operation of the actuator control valve is proportionally controlled in accordance with the amount of operation of the operating member. A control signal for reducing the flow rate of the hydraulic oil is output to the actuator control valve, and the flow rate of the hydraulic oil to be reduced is set for each of the other hydraulic actuators. Effect of the Invention

[0006] According to the above-mentioned working machine, when a hydraulic actuator other than the travel motor is operated while traveling, the flow rate of hydraulic oil supplied to the other hydraulic actuator from the actuator control valve can be reduced, thereby ensuring the flow rate of hydraulic oil supplied to the travel motor and suppressing a decrease in travel speed. [Brief description of the drawings]

[0007] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 1 is a schematic diagram of a hydraulic system. [Figure 4]FIG. 2 is a circuit diagram of a portion of the hydraulic system. [Diagram 5] FIG. 4 is a circuit diagram of a portion of the control valve. [Figure 6] FIG. 4 is a circuit diagram of another portion of the control valve. [Figure 7] FIG. 4 is a circuit diagram of another portion of the control valve. [Figure 8] FIG. 2 is a simplified diagram of a control system. [Figure 9] 5 is a diagram showing the relationship between the operation amount of an operating member and the flow rate of hydraulic oil. FIG. [Figure 10] FIG. 11 is a configuration diagram showing another embodiment of the control valve etc. [Figure 11] FIG. 11 is a configuration diagram showing still another embodiment of the control valve etc. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic side view showing the overall configuration of a working machine 1 according to this embodiment. Fig. 2 is a schematic plan view of the working machine 1. In this embodiment, a backhoe, which is a rotating working machine, is exemplified as the working machine 1. As shown in Figures 1 and 2, the work machine 1 includes a machine body (swivel base) 2, a traveling device 3, and a work device 4. A cabin 5 is mounted on the machine body 2. Inside the cabin 5, a driver's seat 6 is provided where an operator (driver) is seated.

[0009] In this embodiment, the direction toward the front of an operator seated in the driver's seat 6 of the work machine 1 (the direction of the arrow A1 in Figs. 1 and 2) will be described as the forward direction (the front of the machine body), the direction toward the rear of the operator (the direction of the arrow A2 in Figs. 1 and 2) will be described as the rear (the rear of the machine body), and the direction of the arrow K1 in Figs. 1 and 2 will be described as the front-rear direction. Additionally, the direction toward the left side of the operator (the front side in Fig. 1, the direction of the arrow A3 in Fig. 2) will be described as the leftward direction, and the direction toward the right side of the operator (the back side in Fig. 1, the direction of the arrow A4 in Fig. 2) will be described as the rightward direction.

[0010] Additionally, the horizontal direction perpendicular to the front-to-rear direction (aircraft front-to-rear direction) K1 will be described as the aircraft width direction K2 (see FIG. 2). The direction from the center of the aircraft 2 in the width direction toward the right or left will be described as the aircraft width direction outward. In other words, the aircraft width direction outward is the direction away from the center of the aircraft 2 in the width direction in the aircraft width direction K2. The direction opposite to the aircraft width direction outward will be described as the aircraft width direction inward. In other words, the aircraft width direction inward is the direction approaching the center of the aircraft 2 in the width direction K2.

[0011] As shown in Figs. 1 and 2, the traveling device 3 is a device that supports the machine body 2 so that it can travel. This traveling device 3 has a traveling frame 3A, a first traveling device 3L provided on the left side of the traveling frame 3A, and a second traveling device 3R provided on the right side of the traveling frame 3A. The first traveling device 3L and the second traveling device 3R are crawler-type traveling devices. The traveling device 3 is driven by a traveling motor M1 configured by a hydraulic motor (hydraulic actuator). In more detail, the first traveling device 3L is driven by a first traveling motor ML, and the second traveling device 3R is driven by a second traveling motor MR.

[0012] A dozer device 7 is attached to the front of the traveling gear 3. The dozer device 7 is driven by a dozer cylinder C1. More specifically, the dozer cylinder C1 is configured by a hydraulic cylinder (hydraulic actuator), and a blade 7A of the dozer device 7 is raised and lowered by extending and contracting the dozer cylinder C1. 1, the machine body 2 is supported on the traveling device 3 (traveling frame 3A) so as to be rotatable about a rotation axis X1 via a swivel bearing 8. The rotation axis X1 is an axis (vertical axis) that passes through the center of the swivel bearing 8 and extends in the vertical direction.

[0013] 2, the cabin 5 is mounted on one side (left side) in the width direction K2 of the fuselage 2. The cabin 5 is disposed closer to the one side (left side) in the width direction K2 of the fuselage than a center line Y1 that passes through the rotation axis X1 and extends in the front-rear direction K1. As shown in Fig. 2, a prime mover E1 is mounted on the other side (right side) of the body 2 in the width direction K2. The prime mover E1 is mounted vertically on the body 2. Vertically mounted means that the axis of the crankshaft of the prime mover E1 extends in the front-rear direction K1. The prime mover E1 is a diesel engine. Note that the prime mover E1 may be a gasoline engine or an electric motor, or may be a hybrid type having an engine and an electric motor.

[0014] A pressure oil supply unit 18 is provided at the rear of the prime mover E1. The pressure oil supply unit 18 is driven by the power of the prime mover E1 to pressurize and discharge hydraulic oil used in the hydraulic drive unit. The hydraulic drive unit is, for example, a hydraulic actuator or the like provided on the work machine 1. A radiator R1, an oil cooler O1, and a condenser CD are disposed in front of the prime mover E1 and mounted on the machine body 2. The radiator R1 is a cooling device that cools the cooling water (fluid) of the prime mover E1, and the oil cooler O1 is a cooling device that cools the hydraulic oil (fluid). The condenser CD is a cooling device (condenser) that cools the refrigerant (fluid) of an air conditioner provided on the work machine 1.

[0015] A cooling fan F1 that generates cooling air for cooling the motor E1 is provided between the radiator R1 and the motor E1. The cooling fan F1 is driven by the power of the motor E1 to generate cooling air that flows from the front to the rear. As shown in FIG. 1, the machine body 2 has a base plate 9 (hereinafter referred to as a rotating base plate) that rotates around a rotation axis X1. The rotating base plate 9 is formed from a steel plate or the like, and constitutes the bottom of the machine body 2. On the upper surface of the rotating base plate 9, vertical ribs 9A serving as reinforcing members are provided from the front to the rear. In addition to the vertical ribs 9A, members for supporting mounted objects such as equipment mounted on the machine body 2 are provided on the rotating base plate 9, thereby forming a rotating frame that serves as the skeleton of the machine body 2. The horizontal periphery of the rotating frame is covered by a rotating cover.

[0016] A weight 10 is provided at the rear of the machine body 2. The weight 10 is disposed at the rear of the machine body 2, and has a lower portion attached to the rotating base plate 9. As shown in Fig. 2, a fuel tank T1 and a hydraulic oil tank T2 are mounted side by side along the width direction K2 of the aircraft at the rear of the aircraft body 2. The fuel tank T1 is a tank for storing fuel for the engine E1. The hydraulic oil tank T2 is a tank for storing hydraulic oil.

[0017] As shown in FIG. 2, a rotation motor MT is disposed at the front of the rotating base plate 9 (machine body 2) and at the center in the machine body width direction K2. The rotating motor MT rotates the rotating base plate 9 about the rotation axis X1. The rotation motor MT is a hydraulic motor (hydraulic actuator). A swivel joint S1 is provided at the position of the rotation axis X1. The swivel joint S1 is a hydraulic device that circulates hydraulic oil, and is a rotary joint that circulates hydraulic oil between the hydraulic device on the machine body 2 side and the hydraulic device on the traveling gear 3 side. A control valve (hydraulic device) CV is disposed behind the swivel joint S1. The control valve CV is a sectional type composite control valve (hydraulic device) having a plurality of control valves that are stacked and coupled in the vertical direction. A control device U1 is provided below the cabin 5.

[0018] A control device 1B for controlling the work machine 1 is provided in 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 a driver's section 1C. 2, the body 2 has a support bracket 13 at the front slightly to the right of the center in the body width direction K2. The support bracket 13 is fixed to the front of the vertical rib 9A and is provided so as to protrude forward from the body 2.

[0019] 1 and 2, a swing bracket 14 is attached to the front part of the support bracket 13 (the part protruding from the machine body 2) via a swing shaft 14A so as to be swingable about a swing axis X2, which is an axis extending in the vertical direction. Therefore, the swing bracket 14 is rotatable in the machine body width direction K2 (horizontally around the swing shaft 14A).

[0020] As shown in FIG. 1, a working device 4 is supported on the swing bracket 14 (machine body 2). The working device 4 has a boom 15 supported on the machine body 2 so as to be able to swing up and down (swing in the up and down direction), an arm 16 pivotally connected to the boom 15 so as to be able to swing, and a working tool (bucket) 17 pivotally connected to the arm 16 so as to be able to swing.

[0021] The base of the boom 15 is pivotally supported on the upper part of the swing bracket 14 via a pivot. More specifically, the base of the boom 15 is pivotally attached to the upper part of the swing bracket 14 so as to be rotatable about a horizontal axis (an axis extending in the width direction K2 of the machine body) when the boom 15 faces the front direction of the machine body. This allows the boom 15 to swing up and down. The arm 16 is pivotally supported via a pivot at the tip side of the boom 15. More specifically, the arm 16 is pivotally attached to the boom 15 so as to be rotatable about a horizontal axis when the boom 15 faces the front direction of the machine body. This allows the arm 16 to swing in the front-rear direction K1 or the up-down direction. The arm 16 can also swing in an arm crowding direction D1, which is a direction approaching the boom 15, and an arm dumping direction D2, which is a direction moving away from the boom 15.

[0022] The working implement 17 is pivotally supported on the tip side of the arm 16 via a pivot. More specifically, the working implement 17 is pivotally attached to the arm 16 so as to be rotatable about a horizontal axis when the boom 15 faces the front of the machine body. This allows the working implement 17 to swing in a direction approaching the arm 16 (bucket crowding direction) and in a direction moving away from the arm 16 (bucket dump direction). In addition, a bucket as the working implement 17 is provided on the arm 16 so as to be capable of scooping and dumping operations. The scooping operation is an operation of swinging the working implement 17 in a direction approaching the boom 15, for example, an operation for scooping up soil and sand. In addition, the dumping operation is an operation of swinging the working implement 17 in a direction away from the boom 15, for example, an operation for dropping (discharging) the scooped up soil and sand.

[0023] As the work tool 17, instead of a bucket, it is possible to attach work tools (attachments) such as pallet forks and manifold forks, or work tools (hydraulic attachments) having hydraulic actuators such as grapples, hydraulic crushers, angle brooms, earth augers, snow blowers, sweepers, mowers, and hydraulic breakers. The swing bracket 14 can swing by extending and retracting a swing cylinder C2 provided in the machine body 2. The boom 15 can swing up and down by extending and retracting a boom cylinder C3. The arm 16 can swing in an arm crowding direction D1 and an arm dumping direction D2 by extending and retracting an arm cylinder C4. The working tool 17 can swing in a bucket crowding direction and a bucket dumping direction by extending and retracting a working tool cylinder (bucket cylinder) C5. The swing cylinder C2, boom cylinder C3, arm cylinder C4, and working tool cylinder C5 are configured by hydraulic cylinders (hydraulic actuators).

[0024] Next, a hydraulic system for operating the various hydraulic actuators ML, MR, MT, C1 to C6 equipped in the work machine 1 will be described with reference to Figs. 3, the hydraulic system has a control valve CV, a pressure oil supply unit 18, and a flow rate control unit 19. The control valve CV is configured by arranging in one direction and aggregating control valves V1 to V10 that control various hydraulic actuators ML, MR, MT, C1 to C6, an inlet block B2 for taking in pressure oil, and a pair of outlet blocks B1, B3 for discharging pressure oil.

[0025] As shown in FIG. 3, in this embodiment, the control valve CV is configured by sequentially arranging (from the right in FIG. 3 ) the first outlet block B1, the implement control valve V1 that controls the implement cylinder C5, the boom control valve V2 that controls the boom cylinder C3, the first dozer control valve V3 that controls the dozer cylinder C1, the second travel control valve V4 that controls the travel motor MR of the second traveling unit 3R, the inlet block B2, the first travel control valve V5 that controls the travel motor ML of the first traveling unit 3L, the second dozer control valve V6 that controls the dozer cylinder C1, the arm control valve V7 that controls the arm cylinder C4, the swing control valve V8 that controls the swing motor MT, a swing control valve V9 that controls the swing cylinder C2, an SP control valve V10 that controls the attachment actuator (hydraulic actuator) C6 equipped on the hydraulic attachment when a hydraulic attachment is attached as the implement 17, and the second outlet block B3, and connecting these valves to each other.

[0026] As shown in Figs. 4 to 7, each of the control valves V1 to V10 is configured by incorporating directional control valves DV1 to DV10 and a pressure compensation valve (compensator valve) V11 in a valve body. The directional control valves DV1 to DV10 are valves that switch the direction of hydraulic oil to the hydraulic actuators ML, MR, MT, C1 to C6 that are the control targets. The pressure compensation valve V11 is disposed on the downstream side of the pressure oil supply to the directional control valves DV1 to DV10 and on the upstream side of the pressure oil supply to the hydraulic actuators ML, MR, MT, C1 to C6 that are the control targets. The pressure compensation valve V11 functions to adjust the load between the hydraulic actuators ML, MR, MT, C1 to C6 when multiple of the control valves V1 to V10 are used.

[0027] A first relief valve V12 and a first unloading valve V13 are incorporated in the first outlet block B1, and a traveling independent valve V14 is incorporated in the inlet block B2. The first relief valve V12 is a main relief valve that determines the pressure of the hydraulic oil discharged from a first pressure oil discharge port P1, which will be described later. The travel independent valve V14 is constituted by a direct acting spool type switching valve and is constituted by a pilot operated switching valve which is switched by a pilot control pressure.

[0028] A second relief valve V15 and a second unloading valve V16 are assembled in the second outlet block B3. The second relief valve V15 is a main relief valve that determines the pressure of the hydraulic oil discharged from a second pressure oil discharge port P2, which will be described later. Each of the directional control valves DV1 to DV10 is configured as a direct acting spool type switching valve. Also, each of the directional control valves DV1 to DV10 is a control valve electrically controlled by the control device U1. More specifically, each of the directional control valves DV1 to DV10 employs, for example, a pilot type proportional solenoid valve. A pilot type proportional solenoid valve is a valve that controls the direction and flow rate of the hydraulic oil by moving a spool with a pilot control pressure controlled by a proportional solenoid. More specifically, a pilot type proportional solenoid valve is a two-stage directional and flow rate control valve that employs a proportional solenoid pressure reducing valve having two proportional solenoids in the pilot section, and the flow rate is controlled by changing the input current to the proportional solenoid, and the direction is controlled by applying a current to either of the two proportional solenoids.

[0029] As shown in Fig. 4, the hydraulic pump serving as the pressure oil supply source in this hydraulic system includes a first pump 21 for supplying hydraulic oil that operates the hydraulic actuators ML, MR, MT, C1 to C6, and a second pump 22 for supplying signal pressure oil such as pilot control pressure and detection signals. The first pump 21 and second pump 22 are provided in the pressure oil supply unit 18 and are driven by a prime mover E1.

[0030] The first pump 21 is a variable displacement pump, and in this embodiment, is configured as a swash plate type variable displacement axial pump having a function of an equal flow rate double pump that discharges equal amounts of hydraulic oil from two independent pressure oil discharge ports P1, P2. More specifically, the first pump 21 is 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.

[0031] One pressure oil discharge port from the first pump 21 is referred to as a first pressure oil discharge port P1, and the other pressure oil discharge port is referred to as a second pressure oil discharge port P2. In this embodiment, the pressure oil discharge port discharged from the hydraulic pump having two pump functions is defined as the first and second pressure oil discharge ports P1, P2, however, the pressure oil discharge port of one of two hydraulic pumps formed separately may be defined as the first pressure oil discharge port, and the pressure oil discharge port of the other hydraulic pump may be defined as the second pressure oil discharge port.

[0032] The pressure oil supply unit 18 is also provided with a pressing piston 23 that presses the swash plate of the first pump 21 , and a flow rate compensation piston 24 that controls the swash plate of the first pump 21 . The first pump 21 is configured such that the self-pressure of the first pump 21 presses the swash plate in a direction increasing the pump flow rate via the pressing piston 23, and such that a force countering 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.

[0033] Therefore, when the pressure acting on the flow rate compensation piston 24 is released, the swash plate angle of the first pump 21 becomes MAX and the first pump 21 delivers the maximum flow rate. As shown in FIG. 4, the flow control unit 19 controls the swash plate of the first pump 21. The swash plate control of the first pump 21 is performed by controlling the pressure acting on the flow compensation piston 24 through a flow compensation valve V17 provided in the flow control unit 19.

[0034] In addition, the pressure oil supply unit 18 is provided with a spring 25 and a spool 26 for controlling the pump horsepower (torque) of the first pump 21, and is configured to limit the horsepower (torque) that the first pump 21 absorbs from the prime mover E1 when the discharge pressure of the first pump 21 reaches a preset pressure. The second pump 22 is constituted by a fixed displacement gear pump, and the oil discharged from the second pump 22 is discharged from a third pressure oil discharge port P3.

[0035] The first pressure oil discharge port P1 is connected to the inlet block B2 via a first discharge passage a, and the second pressure oil discharge port P2 is connected to the inlet block B2 via a second discharge passage b. The first discharge passage a is connected to a first pressurized oil supply passage d, which is formed so as to extend from the inlet block B2 through the valve body of the second travel control valve V4 → the valve body of the first dozer control valve V3 → the valve body of the boom control valve V2 → the valve body of the implement control valve V1 to the first outlet block B1, and is branched in the first outlet block B1 (at the end of the flow path) to be connected to the first relief valve V12 and the first unloading valve V13.

[0036] Hydraulic oil can be supplied from the first pressure oil supply passage d via a pressure oil branch passage f to each of the directional control valves DV4, DV3, DV2, and DV1 of the second travel control valve V4, the first dozer control valve V3, the boom control valve V2, and the implement control valve V1. The first relief valve V12 and the first unloading valve V13 are connected to a drain oil passage g. The drain oil passage g is formed so as to extend from the first outlet block B1 through the valve body of the implement control valve V1 → the valve body of the boom control valve V2 → the valve body of the first dozer control valve V3 → 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 dozer control valve V6 → 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. The hydraulic oil flowing through the drain oil passage g is discharged from the second outlet block B3 to the hydraulic oil tank T2.

[0037] The second discharge passage b is connected to a second pressure oil supply passage e. The second pressure oil supply passage e is formed so as to extend from the inlet block B2 through the valve body of the first travel control valve V5 → the valve body of the second dozer control valve V6 → 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, and is branched off (at the flow path terminal side) in the second outlet block B3 to be connected to the second relief valve V15 and the second unloading valve V16.

[0038] Hydraulic oil can be supplied from the second pressure oil supply passage e via a pressure oil branch passage h to each of the directional control valves DV5, DV6, DV7, DV8, DV9, and DV10 of the first travel control valve V5, the second dozer control valve V6, the arm control valve V7, the rotation control valve V8, the swing control valve V9, and the SP control valve V10. The hydraulic oil supplied to each of the control valves V1 to V10 is supplied to and discharged from each of the hydraulic actuators ML, MR, MT, C1 to C6. That is, the hydraulic system has a hydraulic circuit that supplies and discharges the hydraulic oil to each of the hydraulic actuators ML, MR, MT, C1 to C6.

[0039] The second relief valve V15 and the second unloading valve V16 are connected to a drain oil passage g. The first pressure oil supply passage d and the second pressure oil supply passage e are connected to each other within the inlet block B2 via a communication passage j that crosses the traveling independent valve V14. The traveling independent valve V14 is freely switchable between an independent position 27 where it blocks the flow of pressure oil through the communication passage j and a joining position 28 where it allows the flow of pressure oil through the communication passage j.

[0040] When the travel independent valve V14 is switched to the independent position 27, hydraulic oil from the first pressure oil discharge port P1 can be supplied to the directional control valves DV4, DV3 of the second travel control valve V4 and the first dozer control valve V3, and hydraulic oil from the second pressure oil discharge port P2 can be supplied to the directional control valves DV5, DV6 of the first travel control valve V5 and the second dozer control valve V6, but hydraulic oil from the first pressure oil discharge port P1 is not supplied to the first travel control valve V5 or the second dozer control valve V6, and hydraulic oil from the second pressure oil discharge port P2 is not supplied to the second travel control valve V4 or the first dozer control valve V3.

[0041] In addition, when the traveling independent valve V14 is switched to the merging position 28, the hydraulic oil from the first pressure oil discharge port P1 and the hydraulic oil from the second pressure oil discharge port P2 are merged and can be supplied to the directional control valves DV1 to DV10 of each of the control valves V1 to V10. The third pressure oil discharge port P3 is connected to the inlet block B2 via a third discharge passage m, and the third discharge passage m is branched into a first branch oil passage m1 and a second branch oil passage m2 midway and connected to the inlet block B2.

[0042] The first branch oil passage m1 is connected to a pressure receiving portion 14a on one side of the traveling independent valve V14 via a first signal oil passage n1, and the second branch oil passage m2 is connected to a pressure receiving portion 14b on the other side of the traveling independent valve V14 via a second signal oil passage n2. A first detection oil passage r1 is connected to the first signal oil passage n1, and a second detection oil passage r2 is connected to the second signal oil passage n2.

[0043] The first detection oil line r1 is connected from the first signal oil line n1 to the drain oil line g via the directional control valve DV6 of the second dozer control valve V6 → 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 dozer control valve V3. The second detection oil line r2 is connected from the second signal oil line n2 to the drain oil line g via 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 rotation control valve V8 → the directional control valve DV7 of the arm control valve V7 → the directional control valve DV6 of the second dozer control valve V6 → 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 dozer control valve V3 → the directional control valve DV2 of the boom control valve V2 → the directional control valve DV1 of the implement control valve V1.

[0044] The traveling independent valve V14 is held at the joining position 28 by the force of a spring when the directional control valves DV1 to DV10 of the respective control valves V1 to V10 are in neutral. When any of the directional control valves DV of the second travel control valve V4, the first travel control valve V5, the first dozer control valve V3, and the second dozer control valve V6 is operated from the neutral position, pressure is generated in the first detection oil line r1 and the first signal oil line n1, and the travel independent valve V14 is switched from the junction position 28 to the independent position 27.

[0045] Therefore, when only traveling, when the dozer device 7 is used while traveling, or when only the dozer device 7 is used, hydraulic oil from the first pressure oil discharge port P1 is supplied to the second travel control valve V4 and the directional control valves DV of the first dozer control valve V3, and hydraulic oil from the second pressure oil discharge port P2 is supplied to the first travel control valve V5 and the directional control valves DV of the first dozer control valve V3.

[0046] At this time, when any of the directional control valves DV10, DV9, DV8, DV7, DV2, DV1 of the SP control valve V10, swing control valve V9, rotation control valve V8, arm control valve V7, boom control valve V2, and implement control valve V1 is operated from the neutral position, pressure is generated in the second detection oil passage r2 and the second signal oil passage n2, and the traveling independent valve V14 is switched from the independent position 27 to the junction position 28.

[0047] In addition, when the directional control valves DV1 to DV10 of each control valve V1 to V10 are in neutral, the travel independent valve V14 is in the junction position 28 even when any of the directional control valves DV10, DV9, DV8, DV7, DV2, and DV1 of the SP control valve V10, swing control valve V9, rotation control valve V8, arm control valve V7, boom control valve V2, and implement control valve V1 is operated from the neutral position.

[0048] Therefore, the boom 15, arm 16, working implement 17, swing bracket 14, machine body 2, and dozer device 7 can be operated simultaneously whether the vehicle is traveling or not. This hydraulic system is also equipped with an auto idling control system (AI system) that automatically operates the accelerator device of the prime mover E1. 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, and the AI ​​switch 29 is connected to the control device.

[0049] In this AI system, when the directional control valves DV1 to DV10 of each control valve V1 to V10 are in neutral, no pressure is generated in the first branch oil passage m1 and the second branch oil passage m2, so that the AI ​​switch 29 does not operate in response to pressure. In this state, the governor is automatically controlled by an electric actuator or the like to throttle down to a preset idling position.

[0050] Furthermore, when any one of the directional control valves DV1-DV10 of the control valves V1-V10 is operated, pressure is generated in the first branch oil passage m1 or the second branch oil passage m2, and this pressure is detected by the AI ​​switch 29, which then operates in a pressure-sensitive manner. Then, a command signal is sent from the control device to an electric actuator or the like, which automatically controls the governor to increase the accelerator up to the set accelerator position.

[0051] In addition, a load sensing system is adopted in this hydraulic system. The load sensing system of this embodiment includes a pressure compensating valve V11 provided in each of the control valves V1 to V10, a flow rate compensating piston 24 that controls the swash plate of the first pump 21, a flow rate compensating valve V17 provided in the flow rate control section 19, the first and second relief valves V12 and V15, and the first and second unloading valves V13 and V16. The load sensing system of this embodiment employs a post-orifice type load sensing system in which the pressure compensating valve V11 is provided downstream of the pressure oil supply to the directional control valves DV1 to DV10.

[0052] In this load sensing system, when multiple hydraulic actuators ML, MR, MT, C1-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-C6, and generates a pressure loss corresponding to the differential pressure from the maximum load pressure in the control valves V1-V10 on the low load pressure side, and allows (distributes) a flow rate according to the operation amount of the spools of the directional control valves DV1-DV10 regardless of the magnitude of the load. In other words, the load sensing system controls the first pump 21 so that the differential pressure obtained by subtracting the maximum load pressure of the multiple hydraulic actuators ML, MR, MT, C1-C6 from the discharge pressure of the first pump 21 is kept at a constant pressure.

[0053] In addition, the load sensing system controls the discharge volume of the first pump 21 in accordance with 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 by the load from the first pump 21, thereby saving power and improving operability. The load sensing system of this embodiment will now be described in more detail.

[0054] The load sensing system has a PLS signal oil path 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 path x that transmits the discharge pressure of the first pump 21 as a PPS signal pressure to the flow compensation valve V17. The PLS signal oil passage w is provided from the first outlet block B1 through the valve body of the implement control valve V1 → the valve body of the boom control valve V2 → the valve body of the first dozer control valve V3 → the valve body of the second travel control valve V4, and also crosses the travel independent valve V14 through the valve body of the first travel control valve V5 → the valve body of the second dozer control valve V6 → the valve body of the arm control valve V7 → the valve body of the rotation 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 compensating valve V11 in each control valve via a load transmission line y.

[0055] Also, 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. Furthermore, the PLS signal oil passage w is connected to the first unloading valve V13 and the drain oil passage g in the first outlet block B1, and is connected to the second unloading valve V16 and the drain oil passage g in the second outlet block B3.

[0056] When the traveling independent valve V14 is in the junction position 28, the line w1 of the PLS signal oil path w from the traveling independent valve V14 to the first outlet block B1 and the line w2 from the traveling independent valve V14 to the second outlet block B3 are connected, and when the traveling independent valve V14 is switched from the junction position 28 to the independent position 27, the PLS signal oil path w is blocked at the traveling independent valve V14.

[0057] As a result, when the traveling independent valve V14 is set to the independent position 27, the PLS signal oil path w is divided into a line w1 on the side where hydraulic oil is supplied from the first pressure oil discharge port P1, and a line w2 on the side where pressure oil is supplied from the second pressure oil discharge port P2. The PPS signal oil passage x is provided from the traveling independent valve V14 to the other side of the spool of the flow compensation valve V17, and when the traveling independent valve V14 is in the merging position 28, the PPS signal oil passage x is connected to the second pressure oil supply passage e via a connection oil passage z, so that the PPS signal pressure (the discharge pressure of the first pump 21) acts on the other side of the spool of the flow compensation valve V17, and when the traveling 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 becomes zero.

[0058] Further, a spring 30 and a differential pressure piston 31 for applying a control differential pressure to the flow rate compensation valve V17 are provided on one side of the spool of the flow rate compensation valve V17. In the hydraulic system configured as described above, when the directional control valves DV1-DV10 of the control valves V1-V10 are in the neutral position, the travel independent valve V14 is in the joining position 28, and at this time, the flow path terminal side of the first pressure oil supply line d is blocked by the first unloading valve V13 and the flow path terminal side of the second pressure oil supply line e is blocked by the second unloading 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 first pump 21 is flow controlled in a direction to reduce the discharge amount and the first and second unloading valves V16 are opened to drop the discharge oil from the first pump 21 into the hydraulic oil tank T2.

[0059] Therefore, in this state, the discharge pressure of the first pump 21 becomes the pressure set by the first and second unloading valves V13 and V16, and the discharge flow rate of the first pump 21 becomes the minimum discharge flow rate. Next, we will explain the case where two or more of the boom cylinder C3, arm cylinder C4, implement cylinder C5, swing cylinder C2, slewing motor MT, and hydraulic attachment are operated simultaneously, or where one or more of these are operated simultaneously with one or more of the left and right traveling motors ML, MR, and dozer cylinder C1.

[0060] In this case, the traveling independent valve V14 is at the junction position 28, the maximum load pressure acting on the operated hydraulic actuators ML, MR, MT, C1 to C6 becomes the PLS signal pressure, and the discharge pressure (discharge flow rate) of the first pump 21 is automatically controlled so that the PPS signal pressure - PLS signal pressure becomes the control differential pressure (so that the difference between the PPS signal pressure and the PLS signal pressure is maintained at a set value). In other words, when the unloading flow rate through the first and second unloading valves V13, 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 in accordance with the amount of operation of the operated control valve.

[0061] In addition, the pressure compensation valve V11 keeps the differential pressure across the spool of the directional control valves DV1 to DV10 of the operated control valves V1 to V10 constant, and the discharge flow rate of the first pump 21 is diverted to each of the operated hydraulic actuators ML, MR, MT, C1 to C6 in an amount according to the operation amount, regardless of differences in the magnitude of the load acting on the operated hydraulic actuators ML, MR, MT, C1 to C6.

[0062] In addition, when the required flow rate of the hydraulic actuators ML, MR, MT, C1 to C6 exceeds the maximum discharge flow rate of the first pump 21, the oil discharged from the first pump 21 is proportionally distributed to each of the operated hydraulic actuators ML, MR, MT, C1 to C6. In the above case, simultaneous operations (combined operations) are possible in an efficient system. When earthwork work is performed by the dozer device 7 while traveling, the travel independent valve V14 is switched to the independent position 27, 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.

[0063] Therefore, hydraulic oil from the first pressure oil discharge port P1 flows to the second travel control valve V4 and the first dozer control valve V3, but does not flow to the first travel control valve V5 and the second dozer control valve V6. Also, hydraulic oil from the second pressure oil discharge port P2 flows to the first travel control valve V5 and the second dozer control valve V6, but does not flow to the second travel control valve V4 and the first dozer control valve V3. Furthermore, because the PPS signal pressure is zero, the swash plate angle of the first pump 21 becomes MAX and the first pump 21 discharges the maximum flow rate.

[0064] As shown in Fig. 8, the proportional solenoids so1-so10 of the directional control valves DV1-DV10 are connected to the control device U1. The directional control valves DV1-DV10 (the control valves V1-V10) are pilot-operated so that the direction and amount of flow of hydraulic oil to the hydraulic actuators ML, MR, MT, C1-C6 to be controlled are controlled by pilot control pressure according to a control signal (current value supplied to the proportional solenoids so1-so10) transmitted from the control device U1 to the proportional solenoids so1-so10. In other words, the control valves V1-V10 are pilot-operated by pilot control pressure controlled by a control signal transmitted from the control device U1. In other words, the control valves V1-V10 are controlled according to a current value supplied by the control device U1.

[0065] The control device U1 is connected to operating members 41 (first operating device 41A to seventh operating device 41G) that operate the respective directional control valves DV1 to DV10 (respective control valves V1 to V10). The control device U1 supplies (transmits) a current value (control signal) according to the amount of operation of the operating members 41 to the proportional solenoids so1 to so10 of the directional control valves DV1 to DV10 to be operated. The first operating tool 41A and the second operating tool 41B are provided on the control device 1B, and are constituted by handles that an operator seated in the driver's seat 6 grasps and operates, for example.

[0066] The first operating tool 41A can operate two operating objects provided on the work machine 1. For example, the first operating tool 41A can operate the directional control valve DV8 (swing motor MT) (swing operation of the machine body 2) and the directional control valve DV7 (arm cylinder C4) (swing operation of the arm 16). The first operating tool 41A also has a sensor (operation detection unit) 42 (first sensor 42A) that detects the operation direction and operation amount. The first sensor 42A is connected to the control device U1. The control device U1 controls the swing control valve V8 (machine body 2) and the arm control valve V7 (arm 16) based on the detection signal from the first sensor 42A.

[0067] The second operating tool 41B can also operate two operating objects provided on the work machine 1. For example, the second operating tool 41B can operate the directional control valve DV2 (boom cylinder C3) (can swing the boom 15) and can operate the directional control valve DV1 (work tool cylinder C5) (can swing the work tool 17). The second operating tool 41B also has a sensor (operation detection unit) 42 (second sensor 42B) that detects the operation direction and operation amount. The second sensor 42B is connected to the control device U1. The control device U1 controls the boom control valve V2 (boom 15) and the work tool control valve V1 (work tool 17) based on the detection signal from the second sensor 42B.

[0068] The third operating tool 41C is provided on the operation device 1B and is, for example, a lever. The third operating tool 41C can operate the directional control valve DV3 and the directional control valve DV6 (dozer cylinder C1) (can operate the dozer device 7). The third operating tool 41C also has a sensor 42 (third sensor 42C) that detects the operation direction and operation amount. The third sensor 42C is connected to the control device U1. The control device U1 controls the first dozer control valve V3 and the second dozer control valve V6 (dozer device 7) based on the detection signal from the third sensor 42C.

[0069] The fourth operating tool 41D and the fifth operating tool 41E are, for example, configured as pedals that are provided on the floor in front of the driver's seat 6 and are operated by the operator stepping on them. The fourth operating tool 41D can operate the directional control valve DV5 (first traveling motor ML) (can operate the first traveling device 3L). The fourth operating tool 41D also has a sensor 42 (fourth sensor 42D) that detects the operation direction and operation amount. The fourth sensor 42D is connected to the control device U1. The control device U1 controls the first traveling control valve V5 (first traveling device 3L) based on the detection signal from the fourth sensor 42D.

[0070] The fifth operating tool 41E can operate the directional control valve DV4 (second traveling motor MR) (can operate the second traveling device 3R). The fifth operating tool 41E also has a sensor 42 (fifth sensor 42E) that detects the operation direction and operation amount. The fifth sensor 42E is connected to the control device U1. The control device U1 controls the second traveling control valve V4 (second traveling device 3R) based on a detection signal from the fifth sensor 42E.

[0071] The sixth operating tool 41F is, for example, a switch (such as a seesaw switch or a slide switch) provided on the first operating tool 41A or the second operating tool 41B. The sixth operating tool 41F can operate the directional control valve DV9 (swing cylinder C2) (can operate the swing bracket 14). The sixth operating tool 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 controls the swing control valve V9 (swing bracket 14) based on the detection signal from the sixth sensor 42F.

[0072] The seventh operating tool 41G is, for example, configured with a switch (such as a seesaw switch or a slide switch) provided on the first operating tool 41A or the second operating tool 41B. The seventh operating tool 41G is capable of operating the directional control valve DV10 (hydraulic actuator of the hydraulic attachment) (capable of operating the hydraulic attachment as a working tool). The seventh operating tool 41G also has a sensor 42 (seventh sensor 42G) that detects the operation direction and operation amount. The seventh sensor 42G is connected to the control device U1. The control device U1 controls the SP control valve V10 (hydraulic attachment) based on the detection signal from the seventh sensor 42G.

[0073] The configuration of the sensor 42 (first sensor 42A to seventh sensor 42G) is not particularly limited, but for example, a potentiometer or the like can be used. The spool of each of the directional control valves DV1-DV10 is moved in proportion to the amount of operation of the corresponding operating member 41 that operates the corresponding directional control valve DV1-DV10 (each of the control valves V1-V10), and an amount of hydraulic oil proportional to the amount by which each of the directional control valves DV1-DV10 is moved is supplied to the hydraulic actuators ML, MR, MT, C1-C6 that are the control targets. In other words, the operating speed of the operation targets (controlled targets) can be changed in proportion to the amount of operation of each operating member 41.

[0074] As described above, the control valves V1 to V10 are operated by operating the operating member 41, which in turn operates the corresponding hydraulic actuators ML, MR, MT, C1 to C6. The hydraulic actuators ML, MR, MT, C1 to C6 then drive the drive parts (machine body 2, traveling gear 3, dozer unit 7, boom 15, arm 16, work tool 17, and hydraulic attachments).

[0075] As shown in FIG. 8, the control device U1 has a control unit Ua and an actuator flow rate suppression unit Ub. The control unit Ua controls the actuator control valve AV when another hydraulic actuator AC (actuator control valve AV that controls the other hydraulic actuator AC) different from the traveling motor M1 is operated independently.

[0076] The actuator flow rate suppression unit Ub controls the actuator control valve AV when the traveling motor M1 (first traveling control valve V5 and second traveling control valve V4) and another hydraulic actuator AC (actuator control valve AV) are operated in a combined manner. The combined operation means operating at least two (multiple) control valves V1 to V10 simultaneously. More specifically, when the traveling device 3 is driven and another hydraulic actuator AC other than the traveling motor M1 is operated, the actuator flow rate suppression unit Ub controls the flow rate of hydraulic oil supplied from the actuator control valve AV that controls the other hydraulic actuator AC to the other hydraulic actuator AC. The other hydraulic actuator AC is, for example, the swing motor MT, the boom cylinder C3, the arm cylinder C4, and the implement cylinder C5, which are operated by the first operating tool 41A and the second operating tool 41B, and the actuator control valve AV is the swing control valve V8, the boom control valve V2, the arm control valve V7, and the implement control valve V1. In other words, the actuator flow rate suppression unit Ub controls the flow rate of hydraulic oil supplied from the actuator control valve AV to the other hydraulic actuator AC when the traveling device 3 (first traveling control valve V5, second traveling control valve V4), the implement 4 (boom control valve V2, arm control valve V7, implement control valve V1), and the machine body 2 (swing control valve V8) are operated in a combined manner.

[0077] As other hydraulic actuators AC, a swing cylinder C2 and an attachment actuator C6 may be added. FIG. 9 is a graph showing the relationship between the operation amount of the operating member 41 and the flow rate of hydraulic oil, where the horizontal axis represents the operation amount of the operating member 41 and the vertical axis represents the flow rate of hydraulic oil supplied from the actuator control valve AV to the corresponding other hydraulic actuator AC.

[0078] A first line 50 in FIG. 9 shows a case where the control unit Ua controls the flow rate of hydraulic oil supplied from the actuator control valve AV to the corresponding other hydraulic actuator AC in response to the operation amount of the operating member 41. The second line 51 in Figure 9 indicates the case where the actuator flow rate suppression unit Ub controls the flow rate of hydraulic oil supplied from the actuator control valve AV (swing control valve V8, boom control valve V2, arm control valve V7, implement control valve V1) to other hydraulic actuators AC (swing motor MT, boom cylinder C3, arm cylinder C4, implement cylinder C5) in response to the operation amount of the operating member 41.

[0079] As can be seen from the first line 50 and the second line 51 in Fig. 9, when the operation amount of the operating member 41 is the same in the case of operating the other hydraulic actuator AC (actuator control valve AV) alone and in the case of operating the travel motor M1 (first travel control valve V5 and second travel control valve V4) and the other hydraulic actuator AC (actuator control valve AV) in a combined manner, the flow rate of hydraulic oil supplied from the actuator control valve AV to the other hydraulic actuator AC is smaller in the case of operating the travel motor M1 (first travel control valve V5 and second travel control valve V4) and the other hydraulic actuator AC (actuator control valve AV) in a combined manner than in the case of operating the other hydraulic actuator AC (actuator control valve AV) alone. In other words, when operating the travel motor M1 (first travel control valve V5 and second travel control valve V4) and the other hydraulic actuator AC (actuator control valve AV) in a combined manner, the flow rate of hydraulic oil supplied to the other hydraulic actuator AC is reduced relative to the operation amount of the operating member 41.

[0080] That is, the actuator flow rate suppression unit Ub causes the actuator control valve AV to supply hydraulic oil to the other hydraulic actuators AC at a flow rate less than the flow rate of hydraulic oil controlled by the control unit Ua for the same operation amount of the operating member 41. Also, when the other hydraulic actuators AC are operated while the travel motor M1 is being operated, the actuator flow rate suppression unit Ub reduces the flow rate of hydraulic oil supplied to the other hydraulic actuators AC from the actuator control valve AV. In other words, the actuator flow rate suppression unit Ub causes the actuator control valve AV to supply hydraulic oil to the other hydraulic actuators AC at a flow rate less than the flow rate of hydraulic oil controlled by the control unit Ua in accordance with the operation amount for the operation amount of the operating member 41.

[0081] In this embodiment, the flow rate of hydraulic oil supplied from the actuator control valve AV to the other hydraulic actuator AC is reduced by reducing the pilot control pressure controlled by a control signal sent from the control device U1 to the actuator control valve AV. In other words, the flow rate of hydraulic oil supplied from the actuator control valve AV to the other hydraulic actuator AC is reduced by reducing the current value supplied by the control device U1 to the actuator control valve AV.

[0082] In addition, the amount of reduction in the flow rate of hydraulic oil supplied from the actuator control valve AV to the other hydraulic actuators AC (the amount of reduction in pilot control pressure) may be set for each of the other hydraulic actuators AC (swing motor MT, boom cylinder C3, arm cylinder C4, work tool cylinder C5). Incidentally, in the past, when another hydraulic actuator AC was operated while the vehicle was traveling, the flow rate of hydraulic oil supplied to the traveling motor M1 was taken by the other hydraulic actuator AC, causing a problem that the traveling speed decreased and a shock occurred.

[0083] In this embodiment, when the other hydraulic actuator AC is operated while traveling, the flow rate of hydraulic oil supplied from the actuator control valve AV to the other hydraulic actuator AC is reduced, so the flow rate of hydraulic oil supplied to the traveling motor M1 is secured and a decrease in traveling speed can be suppressed. In addition, since the load sensing system is provided, the intermediate flow rate characteristics are stable, so stable movement can be achieved even if the speed of the other hydraulic actuator AC is reduced by lowering the pilot control pressure to reduce the flow rate of hydraulic oil.

[0084] In this embodiment, the first travel control valve V5 and the second travel control valve V4 are configured to be controlled by a pilot control pressure controlled by a control signal sent from the control device U1, but the present invention is not limited to this and may be configured to be pilot-operated by a pilot control pressure output from a remote control valve operated by an operating member. Furthermore, the first travel control valve V5 and the second travel control valve V4 may be valves that are directly operated (manually operated) by an operating member.

[0085] In addition, in the above hydraulic system, each control valve V1 to V10 (each directional control valve DV1 to DV10) is configured as a pilot-type proportional solenoid valve, and the control device U1 controls the current value supplied to each control valve V1 to V10 to control the pilot control pressure, thereby controlling each control valve V1 to V10, but the present invention is not limited to this configuration. For example, as shown in FIG. 10, each control valve V1 to V10 may be configured as a pilot-operated switching valve that is pilot-operated by a pilot control pressure acting on a pair of pilot pressure receiving parts Va1 and Va2, and a pair of proportional solenoid valves V21 and V22 controlled by a control device U1 may be provided, in which pilot control pressure is supplied from one proportional solenoid valve V21 to one pilot pressure receiving part Va1, and pilot control pressure is supplied from the other proportional solenoid valve V22 to the other pilot pressure receiving part Va2, thereby controlling the direction and amount of flow of hydraulic oil to the hydraulic actuators MT, ML, MR, C1 to C6.

[0086] Also, as shown in FIG. 11, each of the control valves V1 to V10 may be configured as a proportional electromagnetic directional / flow control valve in which a spool is directly driven by a proportional solenoid so11 to which current is supplied from a control device U1. The above-mentioned working machine 1 comprises a body 2, a traveling device 3 that supports the body 2 so that it can travel, a traveling motor M1 constituted by a hydraulic motor that drives the traveling device 3, another hydraulic actuator AC different from the traveling motor M1, an actuator control valve AV that controls the other hydraulic actuator AC, and a control device U1 that controls the actuator control valve AV, and the control device U1 has an actuator flow rate suppression unit Ub that reduces the flow rate of hydraulic oil supplied from the actuator control valve AV to the other hydraulic actuator AC when the other hydraulic actuator AC is operated while the traveling device 3 is being driven.

[0087] According to this configuration, when a hydraulic actuator AC other than the travel motor M1 is operated while traveling, the flow rate of hydraulic oil supplied to the other hydraulic actuator AC from the actuator control valve AV is reduced, thereby ensuring the flow rate of hydraulic oil supplied to the travel motor M1 and suppressing a decrease in travel speed. In addition, the actuator control valve AV is pilot operated by a pilot control pressure controlled by a control signal sent from the control device U1, and the actuator flow rate suppression unit Ub reduces the pilot control pressure when another hydraulic actuator AC is operated while the traveling device 3 is being driven.

[0088] This configuration makes it easy to control the flow rate of the actuator control valve AV. In addition, the actuator control valve AV is controlled according to the current value supplied by the control device U1, and the actuator flow rate suppression unit Ub reduces the current value supplied to the actuator control valve AV when another hydraulic actuator AC is operated while the traveling device 3 is being driven.

[0089] This configuration also makes it easy to control the flow rate of the actuator control valve AV. The control device U1 also includes an operating member 41 that operates the other hydraulic actuator AC, and has a control unit Ua that controls the flow rate of hydraulic oil supplied from the actuator control valve AV to the other hydraulic actuator AC in accordance with the amount of operation of the operating member 41 when the other hydraulic actuator AC is operated alone, and the actuator flow rate suppression unit Ub causes the actuator control valve AV to supply hydraulic oil to the other hydraulic actuator AC at a flow rate that is less than the flow rate of hydraulic oil controlled by the control unit Ua in accordance with the amount of operation of the operating member.

[0090] This configuration also makes it possible to ensure the flow rate of hydraulic oil supplied to the travel motor M1, thereby suppressing a decrease in travel speed. It also includes a boom cylinder C3 that drives a boom 15 supported on the body 2 so that it can swing up and down, an arm cylinder C4 that drives an arm 16 connected to the tip of the boom 15, a work tool cylinder C5 that drives a work tool 17 connected to the tip of the arm 16 so that it can swing, and a swing motor MT, which is a hydraulic motor that rotates the body 2 around an axis extending in the vertical direction. Other hydraulic actuators AC include at least the boom cylinder C3, the arm cylinder C4, the work tool cylinder C5, and the swing motor MT.

[0091] According to this configuration, it is possible to suppress a decrease in traveling speed when the boom 15, the arm 16, the work tool 17, and the machine body 2 are operated while traveling. The vehicle also includes a variable displacement pump 21 that discharges hydraulic oil to operate a plurality of hydraulic actuators MT, ML, MR, C1-C6 including the travel motor M1 and other hydraulic actuators AC, and a load sensing system that controls the pump 21 so that the differential pressure obtained by subtracting the highest load pressure among the plurality of hydraulic actuators MT, ML, MR, C1-C6 from the discharge pressure of the pump 21 is kept at a constant pressure.

[0092] According to this configuration, since the load sensing system is provided, the intermediate flow rate characteristics are stable, so that stable operation can be achieved even if the flow rate of the hydraulic oil is reduced. Although one embodiment of the present invention has been described above, the embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0093] 2. Aircraft 3 Running gear 15. Boom 16 Arm 21 Pump 17 Work tools 41 Operating member AC Other Hydraulic Actuators AV Actuator Control Valve C3 Boom Cylinder C4 Arm Cylinder C5 Tool Cylinder M1 Drive motor MT Swing Motor U1 Control Unit Ua control section Ub Actuator flow rate suppression part

Claims

1. The aircraft and A traveling device that supports the machine body so that it can travel; A travel motor constituted by a hydraulic motor that drives the travel device; Another hydraulic actuator different from the travel motor; An operating member for operating the other hydraulic actuator; an actuator control valve that changes a flow rate of hydraulic oil supplied to the other hydraulic actuator; a control device for controlling an operation of the actuator control valve in response to an amount of operation of the operating member; Equipped with The actuator control valve is a pilot-operated proportional solenoid valve that is pilot-operated by a pilot control pressure that is controlled by a control signal transmitted from the control device, The control device includes: when the other hydraulic actuator is operated independently without driving the travel motor, a control signal for proportionally controlling the operation of the actuator control valve in accordance with the amount of operation of the operating member is output to the actuator control valve, thereby controlling the flow rate of hydraulic oil supplied from the actuator control valve to the other hydraulic actuator; a control signal for proportionally controlling the operation of the actuator control valve in accordance with the amount of operation of the operating member, the control signal being output to the actuator control valve when the other hydraulic actuator is operated while the traveling device is being driven, so that a flow rate of hydraulic oil supplied from the actuator control valve to the other hydraulic actuator is reduced to a value lower than a flow rate of hydraulic oil supplied to the other hydraulic actuator when the other hydraulic actuator is operated alone with the same amount of operation, and the control signal being output to the actuator control valve in accordance with the amount of operation of the operating member, and the amount of hydraulic oil flow to be reduced is set for each of the other hydraulic actuators.

2. The aircraft and A traveling device that supports the machine body so that it can travel; A travel motor constituted by a hydraulic motor that drives the travel device; Another hydraulic actuator different from the travel motor; An operating member for operating the other hydraulic actuator; an actuator control valve that changes a flow rate of hydraulic oil supplied to the other hydraulic actuator; a control device for controlling an operation of the actuator control valve in response to an amount of operation of the operating member; Equipped with the actuator control valve is controlled in response to a current value supplied by the control device; The control device includes: when the other hydraulic actuator is operated independently without driving the travel motor, a current value for proportionally controlling the operation of the actuator control valve in accordance with the amount of operation of the operating member is supplied to the actuator control valve, thereby controlling the flow rate of hydraulic oil supplied from the actuator control valve to the other hydraulic actuator; a current value for proportionally controlling the operation of the actuator control valve in accordance with the amount of operation of the operating member, the current value being supplied to the actuator control valve when the other hydraulic actuator is operated while the traveling device is being driven, so as to reduce the flow rate of hydraulic oil supplied from the actuator control valve to the other hydraulic actuator below the flow rate of hydraulic oil supplied to the other hydraulic actuator when the other hydraulic actuator is operated alone with the same amount of operation, and the amount of current being supplied to the actuator control valve in accordance with the amount of operation of the operating member, and the amount of flow of hydraulic oil being reduced is set for each of the other hydraulic actuators.

3. A boom cylinder that drives a boom supported on the machine body so as to be capable of swinging up and down; an arm cylinder that drives an arm swingably connected to a tip end side of the boom; A working tool cylinder that drives a working tool connected to a tip side of the arm; A rotation motor which is a hydraulic motor for rotating the machine body around an axis extending in the vertical direction; Equipped with 3. The work machine according to claim 1, wherein the other hydraulic actuators include at least the boom cylinder, the arm cylinder, the implement cylinder, and the swing motor.

4. a variable displacement pump that discharges hydraulic oil for actuating a plurality of hydraulic actuators including the travel motor and the other hydraulic actuator; The work machine according to any one of claims 1 to 3, further comprising a load sensing system that controls the pump so that a differential pressure obtained by subtracting a maximum load pressure of the plurality of hydraulic actuators from a discharge pressure of the pump is kept at a constant pressure.

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