JP6723896B2 - Hydraulic traveling device - Google Patents

Description

The present invention relates to a hydraulic traveling device configured such that oil discharged from a first hydraulic pump rotationally drives a first traveling hydraulic motor and oil discharged from a second hydraulic pump rotationally drives a second traveling hydraulic motor. Regarding

As one example of those equipped with such a hydraulic traveling device, a traveling body having left and right crawler mechanisms, a revolving structure provided on the traveling structure so as to be rotatable, and an excavation work provided at a front portion of the revolving structure. There is a power shovel configured with a shovel device for performing the above. In such a power shovel, an engine, a first hydraulic pump and a second hydraulic pump driven by the engine, and left and right traveling hydraulic motors (hereinafter referred to as traveling motors) that rotationally drive the driving wheels of the left and right crawler mechanisms, respectively. ) Are provided, the left traveling motor is rotationally driven by the hydraulic oil discharged from the first hydraulic pump, and the right traveling motor is rotationally driven by the hydraulic oil discharged from the second hydraulic pump to drive the power shovel. Some are configured as described above (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2016-53375

In the power shovel as described above, the hydraulic oil discharged from the first and second hydraulic pumps is attached not only to the left and right traveling motors but also to the swing motor of the swing body, a plurality of cylinders of the shovel device, and the shovel device. The hydraulic actuator of the attached attachment is also supplied and driven. Therefore, if an attempt is made to drive another hydraulic actuator while the power shovel is running, the flow rate of the hydraulic oil supplied to the hydraulic actuator will be smaller than when the power shovel is stopped, and the operation of the hydraulic actuator will be reduced. There was a problem that the speed became slow.

The present invention has been made in view of such a problem, and provides a hydraulic traveling device capable of supplying and driving a sufficient flow rate of hydraulic oil to a hydraulic actuator other than a traveling motor during traveling. The purpose is to

In order to achieve the above object, a hydraulic traveling device according to the present invention includes a first hydraulic pump and a first hydraulic motor driven by hydraulic oil discharged from the first hydraulic pump (for example, right traveling in the embodiment). A motor 16R), a first control valve (for example, the right travel control valve 62 in the embodiment) that controls the supply of hydraulic oil supplied from the first hydraulic pump to the first hydraulic motor, and a second hydraulic pump. A second hydraulic motor driven by the hydraulic oil discharged from the second hydraulic pump (for example, the left travel motor 16L in the embodiment), and hydraulic oil supplied from the second hydraulic pump to the second hydraulic motor. And a second control valve (for example, the first left travel control valve 61 in the embodiment) that controls the supply of the above, and is configured to be rotationally driven by the first hydraulic motor and the second hydraulic motor. Then, a third control valve (for example, the second left travel control valve 75 in the embodiment) that controls the supply of the hydraulic oil supplied from the first hydraulic pump to the second hydraulic motor, and the second control A supply oil passage switching valve that switches which of the hydraulic oil supply-controlled by the valve and the hydraulic oil supply-controlled by the third control valve to be in a state in which the second hydraulic motor can be supplied (for example, in the embodiment. The left traveling line switching valves 102 and 103) are provided. Then, the hydraulic oil supply controlled by the third control valve is switched by the supply oil passage switching valve to a state in which the hydraulic oil can be supplied to the second hydraulic motor, and the first hydraulic oil is discharged by the first hydraulic pump. The hydraulic motor and the second hydraulic motor are driven, and the hydraulic oil discharged from the second hydraulic pump is supplied to another hydraulic actuator to be driven.

In the hydraulic traveling device having the above-mentioned configuration, the traveling hydraulic pressure controller adjusts the discharge hydraulic pressure from the pilot hydraulic pump according to the operation of the pilot hydraulic pump and the traveling operating device (for example, the left traveling operating lever 24L in the embodiment), and the traveling operating device. The pilot valve (for example, the left traveling pilot valve 81 in the embodiment) that generates the pilot pressure of the second control valve and the third control valve according to the operation of, and the pilot pressure generated by the pilot valve are It is preferable to include a pilot oil passage switching valve (for example, pilot oil passage switching valve 101 in the embodiment) that switches which of the second control valve and the third control valve can be supplied. ..

According to the hydraulic traveling device of the present invention, the third control valve for controlling the supply of the hydraulic oil supplied from the first hydraulic pump to the second hydraulic motor, the hydraulic oil supply-controlled by the second control valve, and And a supply oil passage switching valve for switching which of the operating oils supplied and controlled by the third control valve can be supplied to the second hydraulic motor. Therefore, by switching the supply oil passage switching valve, the first hydraulic motor and the second hydraulic motor are driven by the hydraulic oil discharged from the first hydraulic pump, and the hydraulic oil discharged from the second hydraulic pump is changed to the second hydraulic pressure. It can be supplied to another hydraulic actuator and used for driving without being supplied to the motor. Therefore, it is possible to supply a sufficient amount of hydraulic oil to the hydraulic actuator to drive it even during traveling.

It is a perspective view of the power shovel which is an example of the working machine carrying the hydraulic travel device concerning the present invention. It is a block diagram which shows the control structure of the said power shovel. It is a hydraulic circuit diagram showing a configuration of the hydraulic traveling device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a power shovel 1 which is an example of a working machine equipped with a hydraulic traveling device according to the present invention. The power shovel 1 includes a traveling body 10 configured to be capable of traveling, a revolving structure 20 provided on the upper part of the traveling structure 10 so as to be horizontally rotatable, and a shovel device 30 provided in a front portion of the revolving structure 20. Configured.

The traveling body 10 includes drive wheels, a plurality of driven wheels, and crawler mechanisms 15</b>L and 15</b>R each having a crawler belt 13 wound around these wheels, on both left and right sides of the traveling body frame 11. The left and right crawler mechanisms 15L and 15R are respectively configured to include traveling motors 16L and 16R that rotationally drive the drive wheels. The traveling body 10 is configured to be capable of traveling in any direction and speed by controlling the rotation direction and rotation speed of the left and right travel motors 16L and 16R. A blade 18 is provided at a front portion of the traveling body frame 11 so as to be vertically swingable. The blade 18 is configured to be vertically swingable by expanding and contracting a blade cylinder 19 that is provided so as to extend between the blade 18 and the traveling body frame 11.

At the center of the upper part of the traveling body frame 11, an inner wheel fixed to the traveling body frame 11, an outer wheel fixed to the revolving structure 20, and a revolving motor 21 provided on the revolving structure 20 (see FIGS. 2 and 3). A revolving mechanism (not shown) having a rotary center joint for supplying hydraulic oil from the hydraulic pump provided on the revolving structure 20 to the left and right traveling motors 16L and 16R provided on the traveling structure 10 and the blade cylinders 19. Is provided. The revolving structure 20 is horizontally rotatably attached to the traveling body frame 11 via this revolving mechanism, and is configured to be capable of revolving left and right with respect to the traveling structure 10 by rotating the revolving motor 21 in the forward or reverse direction. There is. A body-side bracket 22 protruding forward is provided on the front part of the revolving unit 20.

The shovel device 30 includes a boom bracket 39 attached to the main body side bracket 22 so as to be rotatable (horizontally rotatable) about an up-down axis, and a boom bracket 39 which is vertically swingable (movable up and down) by a first swing pin 35a. ) Attached to the boom 31, an arm 32 attached to the tip of the boom 31 so as to be vertically swingable (flexible and extendable) by a second swing pin 35b, and a link mechanism 33 provided at the tip of the arm 32. And is configured. Further, the shovel device 30 includes a swing cylinder 34 (see FIGS. 2 and 3) provided between the swing body 20 and the boom bracket 39, and a boom cylinder 36 provided between the boom bracket 39 and the boom 31. And a bucket cylinder 38 that is provided between the arm 32 and the link mechanism 33, and an arm cylinder 37 that is provided between the boom 31 and the arm 32.

The boom bracket 39 is configured to be rotatable (swingable) in a horizontal plane with respect to the revolving unit 20 (main body side bracket 22) by expanding and contracting the swing cylinder 34. The boom 31 is configured to be movable up and down with respect to the revolving structure 20 by expanding and contracting the boom cylinder 36. The arm 32 is configured to be capable of bending and extending with respect to the boom 31 by expanding and contracting an arm cylinder 37.

Various attachments such as a bucket, a breaker, a crusher, a cutter, and an auger device can be vertically swingably attached to the tip ends of the arm 32 and the link mechanism 33, and these attachments extend and retract the bucket cylinder 38. By doing so, it is configured to be swingable with respect to the arm 32 via the link mechanism 33. First to third attachment connection ports 41 to 43 to which hydraulic hoses for supplying hydraulic oil to the hydraulic actuators of these attachments can be connected are arranged on the left side surface of the arm 32.

The revolving unit 20 is provided with a substantially rectangular box-shaped operator cabin 23. Inside the operator cabin 23, an operator seat for the operator to sit down facing forward, a pair of left and right traveling operation levers 24L and 24R (see FIG. 2) for operating the traveling body 10, and a revolving body 20. A pair of left and right work operation levers 25L, 25R and work operation pedals 26L, 26R (see FIG. 2) for operating the shovel device 30 and a blade operation lever 27 for operating the blade 18 are provided. .. Further, various switches operated by an operator are provided inside the operator cabin 23, and an attachment priority switch 28 is provided as one of those switches. The attachment priority switch 28 switches the supply source of hydraulic oil to the left and right traveling motors 16L and 16R to supply a sufficient amount of hydraulic oil to the hydraulic actuator of the attachment mounted on the arm 32 during traveling. It is operated, and is configured to be able to select one of "on" and "off" modes. The switching configuration of the hydraulic pressure supply source will be described in detail later.

In such a power shovel 1, the operator sits on the operator seat and tilts the left and right traveling operation levers 24L and 24R back and forth, so that the left and right crawler mechanisms 15L and 15R are operated according to the operation direction and operation amount. The power shovel 1 can be driven by driving. In addition, by tilting the left and right work operation levers 25L and 25R forward and backward or by depressing the left and right work operation pedals 26L and 26R, the shovel device 30 and the like are driven according to their operation direction and operation amount. It is configured to be able to perform work such as excavation.

Specifically, by tilting the left travel operation lever 24L forward, the left travel motor 16L is driven in the forward direction to drive the left crawler mechanism 15L in the forward direction, and by tilting the rearward, this is reversed. Drive to drive in the reverse direction. Similarly, by tilting the right travel operation lever 24R forward, the right travel motor 16R is driven in the forward direction to drive the right crawler mechanism 15R in the forward direction, and the tilt operation is performed in the backward direction to reversely drive it. It is configured to drive in the reverse direction. The left and right traveling operation levers 24L and 24R are provided with pedal portions at their base ends, and the operator operates the pedal portions with his/her foot to tilt the left and right traveling operation levers 24L and 24R back and forth. It can also be operated.

By tilting the right work operation lever 25R forward and backward, the boom cylinder 36 is expanded and contracted to swing (bend and descend) the boom 31 up and down, and by tilting left and right, the bucket cylinder 38 is expanded and contracted. Swing the attached attachment up and down. In the left work operation lever 25L, the arm cylinder 37 is extended/contracted by tilting forward/backward to vertically swing (bend/extend), and the swing motor 21 is driven by tilting left/right. The revolving unit 20 is turned to the left and right. Further, by operating the left and right work operation pedals 26L and 26R, the swing cylinder 34 is extended/contracted to rotate the shovel device 30 in the direction of the pedal on which the pedal is operated. Further, by tilting the blade operating lever 27 back and forth, the blade cylinder 19 is expanded and contracted to swing the blade 18 up and down.

As described above, the hydraulic drive device 50 that supplies hydraulic oil to each hydraulic actuator to drive the hydraulic actuator in accordance with the operation of each operation lever or the like is provided inside the revolving structure 20, and the hydraulic drive device 50 will be described with reference to FIGS. This will be described with reference to FIG.

The hydraulic drive system 50 includes a diesel engine E (hereinafter, referred to as engine E), a first hydraulic pump P1, a second hydraulic pump P2, a third hydraulic pump P3, and a pilot hydraulic pump P4, which are driven by the engine E. Each of the control valve unit 60 that controls the direction and flow rate of the hydraulic oil discharged from the first to third hydraulic pumps P1 to P3 and supplied to each hydraulic actuator, and the control valve unit 60 according to the operation of each operation lever or the like. And a pilot valve unit 80 for generating a pilot pressure for switching the control valve.

The control valve unit 60 includes a first left travel control valve 61 that controls the direction and flow rate of hydraulic oil supplied to the left travel motor 16L, and a right travel control that controls direction and flow rate of hydraulic oil supplied to the right travel motor 16R. A valve 62, a swing control valve 63 for controlling the direction and flow rate of hydraulic oil supplied to the swing motor 21, an arm control valve 64 for controlling the direction and flow rate of hydraulic oil supplied to the arm cylinder 37, and a boom cylinder 36. A boom control valve 65 for controlling the direction and flow rate of the hydraulic oil to be supplied, a bucket control valve 66 for controlling the direction and flow rate of the hydraulic oil to be supplied to the bucket cylinder 38, and a direction and flow rate of the hydraulic oil to be supplied to the swing cylinder 34. And a blade control valve 68 that controls the direction and flow rate of the hydraulic oil supplied to the blade cylinder 19.

Further, the control valve unit 60 is connected to the first attachment control valve 71 for controlling the direction and flow rate of the hydraulic oil supplied to the hydraulic actuator of the attachment connected to the first attachment connection port 41, and the second attachment connection port 42. The second attachment control valve 72 for controlling the direction and flow rate of the hydraulic oil supplied to the hydraulic actuator of the attached attachment, and the direction and flow rate of the hydraulic oil supplied to the hydraulic actuator of the attachment connected to the third attachment connection port 43. And a third attachment control valve 73 for controlling. Further, the control valve unit 60 has a second left travel control valve 75 which is provided separately from the first left travel control valve 61 and controls the direction and flow rate of the hydraulic oil supplied to the left travel motor 16L. Composed.

The first hydraulic pump P1 is driven by the engine E and discharges the hydraulic oil sucked from the hydraulic oil tank T to the first pump oil passage 51. As shown in FIG. 3, in the first pump oil passage 51, the second left travel control valve 75, the right travel control valve 62, the boom control valve 65, and the bucket control are sequentially arranged from the first hydraulic pump P1 side (upstream side). A valve 66 is provided. Each of these control valves 75, 62, 65, 66 is an open center type three-position switching valve in which the valve spool is driven and switched by the pilot pressure generated by the pilot valve unit 80, and the valve spool is set to the neutral position. When located, the working oil discharged to the first pump oil passage 51 is returned to the working oil tank T via the tank oil passage 54. When the valve spool is switched by the pilot pressure, the hydraulic oil discharged to the first pump oil passage 51 is supplied to each hydraulic actuator in the supply direction and the supply amount according to the switching position. There is. The right travel control valve 62 is connected to a branch oil passage 55 that branches from the first pump oil passage 51 upstream of the second left travel control valve 75. The right travel control valve 62 may supply the hydraulic oil discharged from the first hydraulic pump P1 to the right travel motor 16R by bypassing the second left travel control valve 75 via the branch oil passage 55. It is configured to be able to.

The second hydraulic pump P2 is driven by the engine E and discharges the hydraulic oil sucked from the hydraulic oil tank T to the second pump oil passage 52. The second pump oil passage 52 is provided with a first left travel control valve 61, a swing control valve 67, a first attachment control valve 71, and an arm control valve 64 in order from the second hydraulic pump P2 side (upstream side). There is. Each of these control valves 61, 67, 71, 64 is an open center type three-position switching valve similar to the right travel control valve 62, etc., and when the valve spool is in the neutral position, the second pump is operated. The hydraulic oil discharged to the oil passage 52 is returned to the hydraulic oil tank T via the tank oil passage 54. When the valve spool is switched by the pilot pressure from the pilot valve unit 80, the hydraulic oil discharged to the second pump oil passage 52 is supplied to each hydraulic actuator in the supply direction and the supply amount according to the switching position. Is configured.

The third hydraulic pump P3 is driven by the engine E and discharges the hydraulic oil sucked from the hydraulic oil tank T to the third pump oil passage 53. The third pump oil passage 53 is provided with a third attachment control valve 73, a second attachment control valve 72, a blade control valve 68, and a turning control valve 63 in order from the third hydraulic pump P3 side (upstream side). .. Each of these control valves 72, 68, 63 is an open center type three-position switching valve similar to the right travel control valve 62, etc., and when the valve spool is in the neutral position, the third pump oil passage is formed. The downstream end of 53 is connected to a position between the swing control valve 67 and the first attachment control valve 71 in the second pump oil passage 52 via the oil passage 59, and is discharged to the third pump oil passage 53. The hydraulic oil is supplied to the first attachment control valve 71 and the arm control valve 64. Then, when the valve spool is switched by the pilot pressure from the pilot valve unit 80, the hydraulic oil discharged to the third pump oil passage 53 is supplied to each hydraulic actuator in the supply direction and the supply amount according to the switching position. Is configured.

The third attachment control valve 73 is a two-position switching valve in which the valve spool is driven and switched by pilot pressure from the pilot valve unit 80, and when the valve spool is in the neutral position (the position shown in FIG. 3). The hydraulic oil discharged to the third pump oil passage 53 is supplied to the first attachment control valve 71 and the arm control valve 64 via the oil passage 59 similarly to the second attachment control valve 72 and the like. Then, when the valve spool is switched by the pilot pressure, the working oil discharged to the third pump oil passage 53 is supplied to the third attachment connection port in a supply amount according to the switching position. ..

A supply line switching valve 74 is provided in the third pump oil passage 53 on the upstream side (third hydraulic pump P3 side) of the third attachment control valve 73. The supply line switching valve 74 is a two-position switching valve whose valve spool is driven and switched by pilot pressure from the pilot valve unit 80. When the valve spool is located at the neutral position (the position shown in FIG. 3), the supply line switching valve 74 controls the hydraulic oil discharged to the third pump oil passage 53 as described above by the third attachment control valve 73. To the boom control valve 65 and the bucket control valve 66 via the first oil passage 56. When the valve spool is switched by the pilot pressure, the working oil discharged to the third pump oil passage 53 is supplied to the boom control valve 65 and the bucket control valve 66 via the first oil passage 56. , Is supplied to the swing control valve 67 via the second oil passage 57, and the supply to the third attachment control valve 73 and the like is restricted. At this time, the hydraulic oil discharged by the second hydraulic pump P2 is also supplied to the boom control valve 65 and the bucket control valve 66 via the second oil passage 57 and the first oil passage 56.

A branch oil passage 58 branched from a third pump oil passage P3 on the upstream side (third hydraulic pump P3 side) of the supply line switching valve 74 is connected to the turning control valve 63. The swing control valve 63 bypasses the supply line switching valve 74, the third attachment control valve 73, the second attachment control valve 72, and the blade control valve 68 via the branch oil passage 58 to bypass the third hydraulic pump P3. The hydraulic oil discharged from the motor is also configured to be supplied to the turning motor 21.

The pilot hydraulic pump P4 is driven by the engine E and discharges the hydraulic oil sucked from the hydraulic oil tank T to the pilot pump oil passage 91. The pressure oil discharged into the pilot pump oil passage 91 is adjusted to a predetermined pilot pressure by a pressure adjusting valve (not shown). A pilot valve unit 80 is provided in the pilot pump oil passage 91.

As shown in FIG. 2, the pilot valve unit 80 generates pilot pressure for switching the valve spools of the first left travel control valve 61 and the second left travel control valve 75 according to the operation of the left travel operation lever 24L. Depending on the operation of the left traveling pilot valve 81, the right traveling pilot valve 82 that generates pilot pressure for switching the valve spool of the right traveling control valve 62 according to the operation of the right traveling operation lever 24R, and the left work operation lever 25L. Of the swing control valve 63 and the arm control valve 64 to generate pilot pressure for switching the spool, and the boom control valve 65 and the bucket control valve 66 according to the operation of the right work operation lever 25R. A boom/bucket pilot valve 84 for generating pilot pressure for switching the spool, and a swing pilot valve for generating pilot pressure for switching the valve spool of the swing control valve 67 according to the operation of the left and right work operation pedals 26L, 26R. 85 and 86, and a blade pilot valve 87 that generates a pilot pressure for switching the valve spool of the blade control valve 68 according to the operation of the blade operating lever 27. In addition, in FIG. 3, illustration of parts other than the left and right traveling pilot valves 81 and 82 is omitted.

As shown in FIG. 3, in the oil passage for supplying the pilot pressure generated by the left travel pilot valve 81, the pilot pressure is supplied to either the first left travel control valve 61 or the second left travel control valve 75. A pilot line switching valve 101 for switching between the two is provided. The pilot line switching valve 101 is a two-position switching valve whose valve spool is switched by a drive signal (electrical signal) output via the controller C (see FIG. 2) when the attachment priority switch 28 is operated. In the pilot line switching valve 101, the pilot spool generated by the left traveling pilot valve 81 when the attachment priority switch 28 is in the off state, the valve spool is switched to the neutral position (the position that is moved downward from the position shown in FIG. 3). The pressure is supplied to the first left travel control valve 61 so that the valve spool of the first left travel control valve 61 can be switched. Further, in the pilot line switching valve 101, when the attachment priority switch 28 is turned on, the valve spool is switched to the position shown in FIG. 3, and the pilot pressure generated by the left travel pilot valve 81 is changed to the second left travel control. The valve 75 is supplied to the valve 75 so that the valve spool of the second left travel control valve 75 can be switched.

In the oil passage (the suction port side oil passage and the discharge port side oil passage of the left traveling motor 16L) that supplies the operating oil controlled by the first left traveling control valve 61 and the second left traveling control valve 75 to the left traveling motor 16L. Is provided with left travel line switching valves 102 and 103 that switch which of the first left travel control valve 61 and the second left travel control valve 75 supplies the operating oil to the left travel motor 16L. Similarly to the pilot line switching valve 101, the left travel line switching valves 102 and 103 are drive signals (electrical signals) output via the controller C (see FIG. 2) when the attachment priority switch 28 is operated. It is a two-position switching valve whose valve spool is switched by. Each of the left travel line switching valves 102 and 103 has its valve spool switched to a neutral position (position moved downward from the position shown in FIG. 3) when the attachment priority switch 28 is in an off state, and the first left travel control valve The hydraulic oil controlled by 61 is supplied to the left traveling motor 16L to bring the left traveling motor 16L into a rotationally drivable state. Further, the left travel line switching valves 102 and 103 respectively have their valve spools switched to the positions shown in FIG. 3 when the attachment priority switch 28 is turned on, and the hydraulic oil controlled by the second left travel control valve 75. Is supplied to the left traveling motor 16L so that the left traveling motor 16L can be rotationally driven.

According to the hydraulic drive device 50 configured as described above, when the attachment priority switch 28 is not operated and is in the OFF state, as described above, the valve spool of the pilot line switching valve 101 is in the neutral position (the position shown in FIG. 3). To a position in which the pilot pressure generated by the left traveling pilot valve 81 can be supplied to the first left traveling control valve 61. Further, the valve spools of the left travel line switching valves 102 and 103 are switched to the neutral position (the position moved downward from the position shown in FIG. 3), and the hydraulic oil controlled by the first left travel control valve 61 is supplied to the left travel motor 16L. Ready to be supplied to. Therefore, when the left and right travel operation levers 24L and 24R are operated, pilot pressures corresponding to the operation direction and operation amount are supplied to the first left travel control valve 61 and the right travel control valve 62, respectively, and the first left travel control is performed. The valve spools of the valve 61 and the right travel control valve 62 are switched. Then, the hydraulic oil discharged from the second hydraulic pump P2 is controlled by the first left travel control valve 61 to the supply direction and the supply amount according to the operation direction and the operation amount of the left travel operation lever 24L, and the left travel motor 16L. And the left traveling motor 16L is rotationally driven. The hydraulic oil discharged from the first hydraulic pump P1 is supplied to the right travel motor 16R by being controlled by the right travel control valve 62 in the supply direction and the supply amount according to the operation direction and the operation amount of the right travel operation lever 24R. Then, the right traveling motor 16R is rotationally driven. In this way, the left and right traveling motors 16L are driven by using the hydraulic oil discharged from both the first and second hydraulic pumps P1 and P2.
, 16R are rotationally driven to drive the power shovel 1.

When the right work operation lever 25R is operated while the power shovel 1 is traveling in this way, the hydraulic oil discharged from the first hydraulic pump P1 is controlled by the boom control valve 65 and the bucket control valve 66. The boom cylinder 36 and the bucket cylinder 38 are supplied to the boom cylinder 36 and the bucket cylinder 38, and the boom cylinder 36 and the bucket cylinder 38 are extended/contracted to vertically swing the attachment mounted on the boom 31 and the arm 32. However, since the boom control valve 65 and the bucket control valve 66 are located on the downstream side of the first pump oil passage 51 with respect to the right travel control valve 62, the flow rate of the hydraulic oil supplied to the boom cylinder 36 and the bucket cylinder 38 is The power shovel 1 decreases compared to when the power shovel 1 is stopped, and the operating speeds of the boom cylinder 36 and the bucket cylinder 38 become slower. Therefore, as described above, the hydraulic oil discharged from the second and third hydraulic pumps P2 and P3 is supplied to the boom control valve 65 and the boom control valve 65 via the supply line switching valve 74, the first oil passage 56 and the second oil passage 57. It can also be supplied to the bucket control valve 66 and supplied to the boom cylinder 36 and the bucket cylinder 38.

When the left work operation lever 25L and the blade operation lever 27 are operated while the power shovel 1 is traveling as described above, the hydraulic oil discharged from the third hydraulic pump P3 causes the turning control valve 63 and the blade. It is controlled by the control valve 68 and supplied to the swing motor 21 and the blade cylinder 19, and the swing motor 21 is driven to rotate and the blade cylinder 19 is extended/contracted to swing the swing body 20 and swing the blade 18 up and down. ..

When the left work operation lever 25L and the left and right work operation pedals 26L and 26R are operated while the power shovel 1 is traveling as described above, the hydraulic oil discharged from the second hydraulic pump P2 is controlled by the arm control. It is supplied to the arm cylinder 37 and the swing cylinder 34 under the control of the valve 64 and the swing control valve 67, and the arm cylinder 37 and the swing cylinder 34 are expanded and contracted to swing the arm 32 up and down and rotate the shovel device 30. You can However, since the swing control valve 67 and the arm control valve 64 are located on the downstream side of the second pump oil passage 52 with respect to the first left travel control valve 61, the flow rate of the hydraulic oil supplied to the swing cylinder 34 and the arm cylinder 37. Becomes smaller than when the power shovel 1 is stopped, and the operating speeds of the swing cylinder 34 and the arm cylinder 37 become slower. In addition, since the first attachment control valve 71 is also on the downstream side of the second pump oil passage 52 with respect to the first left travel control valve 61, the flow rate of the hydraulic oil supplied to the first attachment connection port 41 is equal to that of the power shovel. It is less than when 1 is stopped.

Therefore, the hydraulic drive system 50 is configured to include the attachment priority switch 28, the second left travel control valve 75, the pilot line switching valve 101, and the left travel line switching valves 102 and 103 described above. When the attachment priority switch 28 is turned on, as described above, the valve spool of the pilot line switching valve 101 is switched to the position shown in FIG. 3, and the pilot pressure generated by the left travel pilot valve 81 is changed to the second left travel. The control valve 75 is ready to be supplied. Further, the valve spools of the left travel line switching valves 102, 103 are switched to the positions shown in FIG. 3, and the hydraulic oil controlled by the second left travel control valve 75 can be supplied to the left travel motor 16L.

Therefore, when the left and right traveling operation levers 24L and 24R are operated, pilot pressures corresponding to the operation direction and the operation amount are supplied to the second left traveling control valve 75 and the right traveling control valve 62, respectively, and the second left traveling control is performed. The valve spools of the valve 75 and the right travel control valve 62 are switched. Then, the hydraulic oil discharged from the first hydraulic pump P1 is controlled by the second left travel control valve 75 to the supply direction and the supply amount corresponding to the operation direction and the operation amount of the left travel operation lever 24L, and the left travel motor 16L. And the left traveling motor 16L is rotationally driven. The hydraulic oil discharged from the first hydraulic pump P1 is supplied to the right travel motor 16R by being controlled by the right travel control valve 62 in the supply direction and the supply amount according to the operation direction and the operation amount of the right travel operation lever 24R. Then, the right traveling motor 16R is rotationally driven. In this way, the left and right traveling motors 16L and 16R are rotationally driven using only the hydraulic oil discharged from the first hydraulic pump P1, and the power shovel 1 travels.

In this way, when the left and right traveling motors 16L and 16R are rotationally driven by using only the hydraulic oil discharged from the first hydraulic pump P1 and the power shovel 1 is traveling, the left work operation lever 25L and the left and right working levers 25L and When the work operation pedals 26L and 26R are operated, the hydraulic oil discharged from the second hydraulic pump P2 is supplied to the swing cylinder 34, the first attachment connection port 41 and the arm cylinder 37 without being supplied to the left travel motor 16L. Can be used for driving. Therefore, even when the power shovel 1 is running, it is possible to prevent the flow rate of the hydraulic oil supplied to the swing cylinder 34, the first attachment connection port 41 and the arm cylinder 37 from decreasing. Note that the swing cylinder 34 and the attachment (hydraulic actuator) connected to the first attachment connection port 41 are driven at a low frequency at the same time, and when the swing cylinder 34 is not driven, the hydraulic oil discharged from the second hydraulic pump P2 is used. It is possible to drive the attachment by supplying the maximum flow rate thereof to the attachment.

Although the embodiments of the present invention have been described so far, the scope of the present invention is not limited to the above-described embodiments. For example, in the above-described embodiment, the configuration in which the supply source of the hydraulic oil to the left traveling motor 16L is switched from the second hydraulic pump P2 to the first hydraulic pump P1 has been described, but the arrangement of the left traveling motor 16L and the right traveling motor 16R is described. The configuration may be reversed to switch the supply source of the hydraulic oil to the right traveling motor 16R. Further, in the above-described embodiment, the case where the present invention is applied to the crawler traveling type power shovel has been described, but the present invention can be applied to a wheel traveling type power shovel and a working machine other than the power shovel. It is possible.

P1 First hydraulic pump P2 Second hydraulic pump P4 Pilot hydraulic pump 16L Left traveling motor (second hydraulic motor)
16R Right running motor (first hydraulic motor)
24L left travel control lever (travel control device)
50 Hydraulic drive device (hydraulic traveling device)
61 First left travel control valve (second control valve)
62 Right travel control valve (first control valve)
75 Second left traveling control valve (third control valve)
81 Left traveling pilot valve (pilot valve)
101 Pilot line switching valve (pilot oil passage switching valve)
102, 103 Left traveling line switching valve (supply oil passage switching valve)

Claims (2)

A first hydraulic pump,
A first hydraulic motor driven by hydraulic fluid discharged from the first hydraulic pump;
A first control valve for controlling the supply of hydraulic oil supplied from the first hydraulic pump to the first hydraulic motor;
A second hydraulic pump,
A second hydraulic motor driven by hydraulic fluid discharged from the second hydraulic pump;
A second control valve that controls the supply of hydraulic oil supplied from the second hydraulic pump to the second hydraulic motor,
In a hydraulic traveling device that is rotationally driven by the first hydraulic motor and the second hydraulic motor,
A third control valve for controlling the supply of hydraulic oil supplied from the first hydraulic pump to the second hydraulic motor;
And a supply oil passage switching valve for switching which one of the hydraulic oil supply-controlled by the second control valve and the hydraulic oil supply-controlled by the third control valve is brought into a state in which the second hydraulic motor can be supplied. Prepare,
The hydraulic oil supply controlled by the third control valve is switched by the supply oil passage switching valve to a state in which the hydraulic oil can be supplied to the second hydraulic motor, and the first hydraulic motor is operated by the hydraulic oil discharged from the first hydraulic pump. And a hydraulic traveling device configured to drive the second hydraulic motor and supply hydraulic oil discharged from the second hydraulic pump to another hydraulic actuator for driving. A pilot hydraulic pump,
A pilot valve that regulates a discharge hydraulic pressure from the pilot hydraulic pump according to an operation of the travel operation device to generate pilot pressures of the second control valve and the third control valve according to an operation of the travel operation device;
A pilot oil passage switching valve for switching to which of the second control valve and the third control valve the pilot pressure generated by the pilot valve can be supplied. The hydraulic traveling device according to claim 1.

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