JP2006328765A - Hydraulic feeder for hydraulic shovel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly perform operation of carrying out the pushing operation of an arm and the release operation of a bucket side by side without increasing an operator's burden while improving work efficiency based on the speed increase of the arm. <P>SOLUTION: When operating an arm control valve 50, a confluence selector valve 62 is switched into an arm side confluent position 62a to allow discharge oil from a third hydraulic pump P3 to join operating oil supplied to the arm control valve 50 from a second hydraulic pump P2. On the other hand, when a bucket control valve 40 is operated in a bucket release direction even when the arm control valve 50 is operated more than a fixed quantity from its neutral position, that is, when there is a possibility of performing sediment discharge operation or the like of carrying out the pushing direction operation of the arm and the release operation of the bucket side by side, arm side confluence regulation is performed by returning the confluence selector valve 62 into a confluence intercepting position 62b or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a device that supplies hydraulic pressure to a hydraulic actuator that is provided in a hydraulic excavator and drives a bucket and an arm thereof.

  2. Description of the Related Art Conventionally, as a hydraulic supply device provided in a hydraulic excavator, there is known a device that has a plurality of hydraulic pumps and shares hydraulic supply to a plurality of hydraulic actuators by these hydraulic pumps.

  For example, Patent Document 1 below discloses a hydraulic pressure supply apparatus that employs a so-called three-pump system. In this device, hydraulic oil is supplied from the first hydraulic pump to the boom control valve, bucket control valve, right travel control valve, etc., and hydraulic oil is supplied from the second hydraulic pump to the arm control valve, left travel control valve, etc. On the other hand, independence of the turning control is achieved by supplying hydraulic oil from the third hydraulic pump to the turning control valve.

Further, this Patent Document 1 discloses that the operating oil supplied to the arm control valve is not subjected to the operation when the arm control valve is operated in order to improve the operating speed of the arm cylinder controlled by the arm control valve. A technique for joining the discharge oil of the three hydraulic pumps is disclosed.
JP 2002-155904 A

  As one of the main driving operations performed in the hydraulic excavator, while moving this arm in the pushing direction (the direction in which the arm opens with respect to the boom), the bucket at the tip of the arm is rotated in the opening direction. There is an earth and sand discharge operation for discharging earth and sand in the bucket to a predetermined position (for example, a loading platform of a stopped dump truck). In order to perform this operation smoothly, it is necessary to operate so that the operation in the pushing direction of the arm and the operation in the opening direction of the bucket are well coordinated.

  However, as described in Patent Document 1, in an apparatus in which the discharge oil of the third hydraulic pump is supplied to the arm control valve when the arm control valve is operated, the operating speed of the bucket cylinder that opens the bucket Compared to the above, since the operating speed of the arm cylinder that moves the arm in the pushing direction is increased, the speed balance between the two is lost, and the earth discharging operation cannot be performed smoothly.

  For example, in the backhoe, from the raised state as shown in FIG. 13A, that is, from the state where the boom 26 stands, the arm 28 is closed with respect to the boom 26, and the bucket 30 is closed with respect to the arm 28. The operation of the boom 26 in the inclining direction, the operation in the pushing direction of the arm 28, and the operation in the opening direction of the bucket 30 are simultaneously performed in a discharge state as shown in FIG. When it is desired to shift the arm 28 and the bucket 30 to the open state, if only the operating speed of the arm cylinder is increased as described above, the pushing operation of the arm 28 is preceded and the bucket 30 is opened. Since the movement cannot be followed, as shown in FIG. 5C, the working state in which the bucket 30 is hardly opened even when the arm 28 is fully opened. It may occur.

  In this case, the operator must wait until the bucket 30 is fully opened behind the posture in which only the arm 28 is completely open as shown in FIG. 13C, and smooth operation cannot be expected. Moreover, since the opening operation of the bucket 30 is slow, it is easy to feel irritation. Further, when the operation of lowering the boom 26 is advanced with the posture shown in FIG. 13 (c), there may be a disadvantage that the toe of the bucket 30 that is not sufficiently operated in the opening direction is stuck into the ground.

  In order to avoid such inconvenience, the operator only needs to balance the arm operation speed and the bucket operation speed by suppressing the operation amount of the arm operation lever during the earth and sand discharge operation. It is difficult to adjust the amount, especially for an operator who is not accustomed to increasing the speed of the arm cylinder.

  On the other hand, when driving other than the earth and sand discharge operation, for example, when driving only in the pushing direction of the arm during excavation work, a request to increase the operating speed of the arm to improve the operating efficiency Exists.

  In view of such circumstances, the present invention smoothly performs an operation in which the pushing operation of the arm and the opening operation of the bucket are performed in parallel without increasing the burden on the operator while improving work efficiency by increasing the speed of the arm. An object of the present invention is to provide a hydraulic supply device for a hydraulic excavator that can be used.

  As means for solving the above-mentioned problems, the present invention provides an arm drive actuator for rotating an arm attached to a boom that can be raised and lowered with respect to the aircraft body in the vertical direction, and an arm attached to the tip of the arm. An apparatus for supplying hydraulic pressure to both actuators of a hydraulic excavator provided with a bucket drive actuator for rotating the bucket in a vertical direction with respect to the arm, the first hydraulic pump and the first hydraulic pump The first hydraulic pressure is provided between the hydraulic pump and the bucket driving actuator, and has a neutral position that blocks between the first hydraulic pump and the bucket driving actuator and is operated from the neutral position. Bucket control valve that is switched to a state in which hydraulic fluid is guided from the pump to the bucket drive actuator The neutral position is provided between the second hydraulic pump and the second hydraulic pump and the arm driving actuator, and has a neutral position that blocks between the second hydraulic pump and the arm driving actuator. The hydraulic pressure is applied to an arm control valve that is switched to a state in which hydraulic fluid is guided from the second hydraulic pump to the arm driving actuator by operating from the second hydraulic pump, and a hydraulic actuator different from the bucket driving actuator and the arm driving actuator. A third hydraulic pump to be supplied; an arm-side merging position where the discharge oil of the third hydraulic pump is merged with hydraulic oil supplied from the second hydraulic pump to the arm control valve; and a merging cutoff position where the merging is interrupted And the merge switching valve when the arm control valve is in its neutral position. Is switched to the merging cut-off position, and when the arm control valve is operated more than a certain amount from the neutral position, the merging switching valve is switched to the arm-side merging position, and the arm control valve is moved to the neutral position. Even when the bucket control valve is operated in a direction to rotate the bucket in the opening direction even when the bucket control valve is operated more than a certain amount from the position, the combined flow rate of hydraulic oil from the third hydraulic pump to the arm control valve And a merging control means for performing an arm side merging restricting operation.

  In this device, when the arm control valve is operated more than a certain amount from its neutral position and the bucket control valve is not operated, the merging switching operation for switching the merging switching valve to the arm side merging position, that is, the third hydraulic pressure Since the operation of joining the discharge oil of the pump to the hydraulic oil supplied from the second hydraulic pump to the arm control valve is performed, the operating speed of the arm driving actuator is thereby increased.

  On the other hand, even when the arm control valve is operated more than a certain amount from its neutral position, when the bucket control valve is operated in a direction to rotate the bucket in the opening direction, in other words, the arm The arm that reduces the combined flow rate of the hydraulic fluid from the third hydraulic pump to the arm control valve when there is a possibility that a sediment discharge operation or the like is performed in parallel with the pushing direction operation and the bucket opening operation Since the side merging restricting operation is performed, the speed increase of the arm driving actuator is thereby suppressed, and the balance between the operating speed of the arm driving actuator and the operating speed of the bucket driving actuator is maintained. Accordingly, it is possible to smoothly perform an operation that requires cooperation between the operation in the pushing direction of the arm by the operation of the arm driving actuator and the opening operation of the bucket by the operation of the bucket driving actuator.

  In particular, there is a neutral position between the first hydraulic pump and the boom driving actuator that blocks between the first hydraulic pump and the arm driving actuator, and the operation is performed from the neutral position. When a boom control valve is provided that is switched to a state in which hydraulic oil is guided from the first hydraulic pump to the boom drive actuator, the first hydraulic pressure is also applied to the boom side so as to cause the boom to fall down during the sediment discharge operation or the like. Since the discharge speed of the pump is distributed, the operation speed of the bucket driving actuator is further reduced, so that the suppression of the speed increase of the arm hydraulic actuator becomes more effective.

  In this case, as the merging control means, when the arm control valve is operated more than a certain amount from its neutral position, the bucket control valve is operated in a direction to rotate the bucket in the opening direction, and the boom The arm side merging restriction operation may be performed only when the control valve is operated in a direction that causes the boom to fall down.

  In the present invention, the specific content of the arm side merging restriction operation is not particularly limited. For example, another dedicated control valve (a switching valve or a flow control valve) is provided in the oil passage from the merging switching valve to the merging point. However, even when the arm control valve is operated more than a certain amount from its neutral position, the operation of setting the merging switching valve to the merging cutoff position is performed. By doing so, it is possible to restrict the merging of the hydraulic oil to the arm control valve side without introducing the dedicated control valve.

  The merging switching valve is a flow rate control valve that increases the merging flow rate of hydraulic oil from the third hydraulic pump to the arm control valve as the operation stroke from the merging cutoff position to the arm side merging position increases. As the side merging restriction operation, it is possible to perform more appropriate merging flow rate control by reducing the operation stroke amount from the merging cutoff position of the merging switching valve compared to when the bucket control valve is not operated. become.

  The merging control means, when performing the arm side merging restriction operation, joins the discharge oil of the third hydraulic pump to the hydraulic oil supplied from the first hydraulic pump to the bucket control valve. If the switching operation is performed, not only the acceleration of the arm driving actuator can be suppressed, but also the operating speed of the bucket driving actuator can be increased to increase the overall operating speed while balancing the speeds of both actuators. This makes it possible to achieve both a smooth sediment discharge operation and an improvement in work efficiency.

  As a specific aspect thereof, the merging switching valve is added to the merging cutoff position and the arm-side merging position, and the discharge oil of the third hydraulic pump is supplied from the first hydraulic pump to the bucket control valve. It has a bucket-side merging position for merging with oil, and if the operation for switching the merging switching valve to the bucket-side merging position is performed as the bucket-side merging switching operation, the merging switching valve is switched to arm-side merging. With a simple configuration that is also used for switching the bucket side merging, appropriate merging control can be realized.

  Also, a release command input means for inputting a command for canceling the arm side merge restriction operation of the merge control means, and an arm side merge restriction of the merge control means when the command is input by the release command input means By providing a merging restriction releasing means for releasing the operation, the driver has a state in which the arm-side merging restriction operation is automatically performed and a state in which the operation is not performed according to the driving situation. You can choose.

  As described above, according to the present invention, when the arm control valve is operated more than a certain amount from its neutral position, the discharge oil of the third hydraulic pump is supplied from the second hydraulic pump to the arm control valve. By performing a merge switching operation for merging with oil, the operating speed of the arm drive actuator is increased to improve work efficiency, while the arm control valve is operated more than a certain amount from its neutral position, When the bucket control valve is operated in the bucket opening direction, that is, when there is a possibility that an earth and sand discharge operation or the like in which the operation in the arm pushing direction and the bucket opening operation are performed in parallel is performed. (3) By performing the arm side merging restriction operation that reduces the merging flow rate of hydraulic oil from the hydraulic pump to the arm control valve, the arm load is reduced without increasing the burden on the operator. Operation of the arms of the push direction by the operation of the drive actuator, there is an effect that it is possible to smoothly carry out the bucket actuating soil release operation is parallel with the opening operation of the bucket by the driving actuator and the like.

  A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 2 shows a schematic configuration of a hydraulic excavator (backhoe in the illustrated example) 10 according to the present invention. The machine body of the hydraulic excavator 10 is composed of a lower traveling body 12 and an upper revolving body 14 that is turnably mounted thereon, and a hydraulic motor for causing the upper revolving body 14 to revolve on the lower traveling body 12. Built-in swivel motor.

  The lower traveling body 12 includes left and right traveling crawlers 16L and 16R, and the traveling crawlers 16L and 16R include traveling motors 18L and 18R, respectively, which are hydraulic motors for rotating the iron wheels. A dozer 20 is attached to the frame of the lower traveling body 12, and a dozer cylinder (not shown) that swings the dozer 20 up and down is provided.

  A swing bracket 22 is provided at the front end of the upper swing body 12, and a boom support member 24 is attached to the swing bracket 22 so as to be swingable in the left-right direction. A boom 26 can be raised and lowered on the boom support member 24, and an arm 28 is connected to the tip of the boom 26 so as to be able to rotate in the vertical direction. A bucket 30 is attached to the tip of the arm 28. It is attached so that it can rotate in the vertical direction. Here, the swing of the boom support member 24, the raising and lowering of the boom 26, the rotation of the arm 28 with respect to the boom 26, and the rotation of the bucket 30 with respect to the arm 28, respectively, This is realized by expansion and contraction of the boom cylinder 32, the arm cylinder 34, and the bucket cylinder 36.

  A hydraulic pressure supply device mounted on the hydraulic excavator 10 is shown in FIG. This apparatus includes a first hydraulic pump P1, a second hydraulic pump P2, and a third hydraulic pump P3 for supplying hydraulic pressure to each of the hydraulic actuators, and a pilot pump P4 that is a pilot hydraulic source. Yes.

  The first hydraulic pump P1 is for supplying hydraulic pressure to the left traveling motor 16L, the boom cylinder 32, the bucket cylinder 36, etc. via control valves, respectively. Only the bucket control valve 40 interposed between P1 and the bucket cylinder 36 is depicted.

  This bucket control valve 40 is constituted by a three-position pilot switching valve, and when the pilot pressure is not supplied to any of the pilot chambers 42 and 44, the bucket control valve 40 is held at the neutral position 40a while the pilot pressure is supplied to the pilot chamber 42. When the pilot pressure is supplied to the pilot chamber 44, it is switched to the second drive position 40c. Then, at the neutral position 40a, the first hydraulic pump P1 and the bucket cylinder 36 are disconnected from each other, and the discharged oil of the first hydraulic pump P1 is directly passed through the center bypass passage 46 without passing through the bucket cylinder 36. The center bypass flow path 46 is closed at the first drive position 40b and the oil discharged from the first hydraulic pump P1 is supplied to the head side chamber of the bucket cylinder 36 to arm the bucket 30. 28 is rotated in the closing direction (counterclockwise direction in FIG. 2), and conversely, at the second drive position 40c, the center bypass flow path 46 is closed and the first cylinder is placed in the rod side chamber of the bucket cylinder 36. Bucket opening direction in which the oil discharged from the hydraulic pump P1 is supplied to open the bucket 30 with respect to the arm 28 (clockwise direction in FIG. 2) It is rotated.

  On the other hand, the second hydraulic pump P2 is for supplying hydraulic pressure to the right traveling motor 16L, the boom swing cylinder, the arm cylinder 34, and the like via control valves, respectively. In FIG. Only the arm control valve 50 interposed between the hydraulic pump P2 and the arm cylinder 34 is depicted.

  This bucket control valve 50 is also constituted by a three-position pilot switching valve, similar to the arm control valve 40, and is maintained at the neutral position 50a when no pilot pressure is supplied to any of the pilot chambers 52 and 54, When the pilot pressure is supplied to the pilot chamber 52, the first driving position 50b is switched. Conversely, when the pilot pressure is supplied to the pilot chamber 54, the second driving position 50c is switched. At the neutral position 50a, the second hydraulic pump P2 and the arm cylinder 34 are disconnected from each other, and the oil discharged from the second hydraulic pump P2 is directly released to the tank through the center bypass passage 56, while the first hydraulic pump P2 is allowed to escape to the tank. In the driving position 50b, the center bypass passage 56 is closed and the discharge oil of the second hydraulic pump P2 is supplied to the head side chamber of the arm cylinder 34 to close the arm 28 with respect to the boom 26, that is, arm pulling. 2 is rotated in the direction (counterclockwise in FIG. 2), and at the second drive position 50c, the center bypass flow path 56 is closed and the discharge oil of the second hydraulic pump P2 is placed in the rod side chamber of the arm cylinder 34. And the arm 28 is rotated in the opening direction with respect to the boom 26, that is, in the arm pushing direction (clockwise direction in FIG. 2).

  The third hydraulic pump P3 is for supplying hydraulic pressure to the swing motor and the dozer cylinder. Of these, in FIG. 1, the swing control interposed between the third hydraulic pump P3 and the swing motor. Only valve 60 is depicted.

  The swing control valve 60 is also constituted by a three-position pilot switching valve, similar to the arm control valve 40, and is held at a neutral position (middle position in the figure) when no pilot pressure is supplied to any of the pilot chambers. The oil discharged from the third hydraulic pump P3 is allowed to escape to the center bypass passage 61. On the other hand, when pilot pressure is supplied to any pilot chamber, the neutral hydraulic position is switched to any driving position, and the third hydraulic pump The discharged oil of P3 is guided to the turning motor.

  The center bypass passage 61 is connected to a primary port of the merging switching valve 62. The merging switching valve 62 is constituted by a two-position pilot switching valve. When the hydraulic pressure is not supplied to the pilot chamber 64, the merging switching valve 62 maintains the merging cutoff position 62 a, while the hydraulic pressure is supplied to the pilot chamber 64, the arm side merging position. It is switched to 62b. At the merging cutoff position 62a, the hydraulic oil flowing from the third hydraulic pump P3 through the center bypass passage 61 is released to the entire tank, while at the arm side merging position 62b, the hydraulic oil is passed through the arm side merging oil passage 65. The primary port of the arm control valve 50 is replenished. That is, the hydraulic oil is merged with the hydraulic oil supplied from the second hydraulic pump P2 to the arm control valve 50.

  Next, the configuration of the merging control means for controlling the switching of the merging switching valve 62 will be described.

  The pilot chamber 64 of the merging switching valve 62 is connected to the pilot pump P4 through a pilot line 68 having a throttle 66 in the middle. Further, two pilot pressure release lines 70 and 72 are branched from the pilot line 68 and connected to the tank side. These pilot pressure release lines 70 and 72 are respectively connected to the arm control valve 50 and the bucket control valve. The open / close switching is performed in conjunction with the operation 40.

  Specifically, an arm side child valve 58 is connected to the arm control valve 50 so as to be linked thereto, and this arm side child valve 58 is provided in the pilot pressure release line 70. When the arm control valve 50 is in the neutral position 50a, the arm side child valve 58 maintains the open position 58a for opening the pilot pressure release line 70, while the arm control valve 50 is in the first drive position 50b or the first drive position 50b. When switched to the second drive position 50c, the pilot pressure release line 70 is switched to the cutoff positions 58b and 58c.

  The bucket control valve 40 is connected to a bucket side child valve 48 in conjunction with the bucket control valve 40, and the bucket side child valve 48 is provided in the pilot pressure release line 72. When the bucket control valve 40 is in the neutral position 40a or the first drive position 40b, the bucket side child valve 48 maintains the cutoff positions 48a and 48b that shut off the pilot pressure release line 72, while the bucket control valve 40 Is switched to the second drive position 50c, that is, the position where the bucket 30 is rotated in the bucket opening direction, and the opening position 48c where the pilot pressure release line 72 is opened is switched.

  Next, the operation of this apparatus will be described.

  First, when the arm control valve 50 is not operated, that is, when the arm control valve 50 is in the neutral position 50a, the arm side child valve 58 of the arm control valve 50 is opened to open the pilot pressure release line 70. At the position 58a, a pilot line 68 between the pilot pump P4 and the pilot chamber 64 of the merging switching valve 62 is communicated with the tank through the pilot pressure release line 70. Therefore, no pilot pressure is generated in the pilot line 68, and the merging switching valve 62 is held at the merging / blocking position 62a, so that the operation flows out from the turning control valve 60 through the center bypass passage 61 from the third hydraulic pump P3. The oil is released to the tank as it is without joining the arm control valve 50 side.

  On the other hand, when the arm control valve 50 is operated from the neutral position 50a to the first drive position 50b or the second drive position 50c, the arm side valve 58 is switched to the cutoff position 58b or the cutoff position 58c. In either case, the pilot pressure release line 70 is shut off.

  In this case, the bucket control valve 40 is switched to the neutral position 40a or the first drive position 40b (a position where the discharge oil of the first hydraulic pump P1 is guided to the head side chamber of the bucket cylinder 36 and the bucket 30 is moved in the closing direction). When this is done, the bucket side valve 48 is switched to the shut-off position 48a or the shut-off position 48b, and the pilot pressure release line 72 is also shut off, so that pilot pressure is generated in the pilot line 68 and the merge switching valve 62 The pilot chamber 64 is supplied. As a result, the merging switching valve 62 is switched to the arm-side merging position 62b, and the hydraulic fluid flowing from the third hydraulic pump P3 through the center bypass passage 61 is guided to the arm-side merging oil passage 65, and the arm control is performed from the second hydraulic pump P2. The hydraulic oil supplied to the valve 50 is merged. Thereby, the operating speed of the arm cylinder 34 is increased.

  On the other hand, when the bucket control valve 40 is switched to the second drive position 40c (position where the discharge oil of the first hydraulic pump P1 is guided to the rod side chamber of the bucket cylinder 36 and the bucket 30 is moved in the opening direction) Even if the arm control valve 50 is operated from the neutral position 50a to the first driving position 50b or the second driving position 50c because the bucket side child valve 48 is switched to the opening position 48c and the pilot pressure release line 72 is opened. No pilot pressure is generated in the pilot line 68, and the merging switching valve 62 is maintained at the merging cutoff position 62a. That is, the joining of the discharge oil of the third hydraulic pump P3 to the arm control valve 50 side is released.

  Accordingly, the sediment control operation is performed in which the bucket control valve 40 is switched to the second drive position 40c and the bucket 30 is operated in the opening direction while the arm control valve 50 is switched to the second drive position 50c and the arm 28 is operated in the pushing direction. For example, the speed increase of the arm cylinder 34 due to the merged discharge oil of the third hydraulic pump P3 is released, so that the opening of the bucket 30 due to the contraction of the bucket cylinder 36 due to the speed increase of the arm cylinder 34 is released. The relative movement of the direction is prevented, and the speed balance for smoothly performing the earth and sand discharging operation and the like is maintained.

  In other words, according to this apparatus, when only the arm 28 is operated alone without moving the bucket 30, the operation speed of the arm 28 is increased by confluence of the discharge oil of the third hydraulic pump P3. While improving the efficiency, when the operation of pushing the arm 28 and the opening operation of the bucket 30 are performed in parallel, the merging is stopped and the acceleration of the arm 28 is released, so that the load on the operator can be increased smoothly. Sediment discharge operation etc. can be realized.

  In this embodiment, in order to release the pilot pressure of the merging switching valve 62 in conjunction with the operation of the bucket control valve 40 in order to release the merging, the bucket side valve 48 is connected to the bucket control valve 40. Although the pilot pressure release line 72 is opened and closed by the bucket side child valve 48, a switching valve independent of the bucket control valve 40 may be used.

  An example thereof is shown in FIG. 3 as a second embodiment. In the figure, in the middle of the pilot pressure release line 72, a two-position pilot switching valve 74 independent from the bucket control valve 40 is provided. The pilot switching valve 74 is connected to a pilot line 45, the pilot chamber 75 of which is connected to the pilot chamber 44 for switching the bucket control valve 40 to the second drive position 40 c, and the pilot pressure is applied to the pilot chamber 75. When not supplied, the shutoff position 74a for shutting off the pilot pressure release line 72 is maintained, and when the pilot pressure is supplied to the pilot chamber 75, the pilot pressure release line 72 is switched to the open position 74b. It is like that.

  Further, in this embodiment, an electromagnetic switching valve 76 is provided in series with the pilot switching valve 74 in the pilot pressure release line 72. The electromagnetic switching valve 76 is for manually releasing the arm side merging restriction operation (that is, the operation of setting the merging switching valve 62 to the merging cutoff position 62b) during the earth and sand discharging operation, and the solenoid 78 is excited. If not, the open position 76a for opening the pilot pressure release line 72 is maintained, while the solenoid 78 is energized to switch to the cutoff position 76b for closing the pilot pressure release line 72.

  The solenoid 78 is connected to an operating device 79 provided in the driver's seat. The operation device 79 includes a merging restriction release switch that can be operated by the driver, and is configured to excite the solenoid 78 only when a command to release the merging restriction is input by operating this switch. ing.

  According to this device, when pilot pressure is supplied to the pilot chamber 44 of the bucket control valve 40 and the control valve 40 is switched to the second drive position 40c, that is, the position where the bucket 30 is opened, the pilot pressure is changed to the pilot switching valve 74. Therefore, even if the arm control valve 50 is operated, the pilot pressure is not supplied to the pilot chamber 64 of the merging switching valve 62 because the switching valve 74 is switched to the open position 74b that opens the pilot pressure release line 72. Not supplied, the valve 62 maintains the merge blocking position 62a. That is, the arm side merging restriction operation is performed.

  Further, in this device, when the merge restriction release switch of the operation device 79 is operated and the device 79 excites the solenoid 78 of the electromagnetic switching valve 76, the valve 76 is switched from the open position 76a to the shut-off position 76b. Regardless of the switching position of the pilot switching valve 74, the pilot pressure release line 72 is shut off. That is, the arm side merging restriction operation by the pilot switching valve 74 is released. Therefore, in this state, regardless of the operation position of the bucket control valve 40, when the arm control valve 50 is operated, the merging switching valve 62 is switched to the arm side merging position, and the discharge oil of the third hydraulic pump P3 is supplied to the arm control valve 50. Join the primary side.

  According to this device, the driver uses the merge restriction release switch in the operation device 79 to change between the state in which the arm side merge restriction operation is automatically performed and the state in which the operation is not performed according to the driving situation. Can be freely selected.

  The specific configuration of the merge restriction release means can be set as appropriate. For example, the electromagnetic switching valve 76 is provided in front of the pilot chamber 75 of the pilot switching valve 74 in the apparatus shown in FIG. 3, and the solenoid valve 76 is only activated when the solenoid 78 of the electromagnetic switching valve 76 is excited. Even if the pilot line leading to is cut off, the same effect as described above can be obtained.

  Further, such a merging restriction canceling means can be similarly applied to the first embodiment or the following embodiments.

  The circuit for supplying the pilot pressure to the pilot chamber 64 of the merging switching valve 62 can be set as appropriate. For example, as shown in FIG. 4 as the third embodiment, the pilot pressure of the arm control valve 50 is used. The switching operation of the merging switching valve 62 may be performed.

  In the figure, both inlet ports of the shuttle valve 55 are respectively connected to pilot lines communicating with both pilot chambers 52, 54 of the arm control valve 50, and an output port of the shuttle valve 55 is connected to the merging switching valve 62 via the pilot line 68. A pilot switching valve 67 at two positions is provided in the middle of the pilot line 68.

  The pilot chamber 69 of the pilot switching valve 67 is connected to a pilot line on the pilot chamber 44 side of the bucket control valve 40. When the pilot pressure is not supplied to the pilot chamber 69, the pilot switching valve 67 holds an opening position 67a for opening the pilot line 68. On the other hand, when the pilot pressure is supplied to the pilot chamber 69, the pilot switching valve 67 The line 68 is cut off from the shuttle valve 55 and can be switched to a pilot pressure release position 67b that passes directly to the tank.

  In this apparatus, when the pilot pressure is not supplied to the pilot chamber 44 of the bucket control valve 40, that is, when the bucket control valve 40 is in the neutral position 40a or the first drive position 40b, the pilot of the pilot switching valve 67 is used. Since the pilot pressure is not supplied also to the chamber 69, the pilot switching valve 67 holds the open position 67a. Therefore, in this state, when the pilot pressure is supplied to one of the pilot chambers 52 and 54 of the arm control valve 50 and the arm control valve 50 is operated from the neutral position 50a, the pilot pressure is By supplying the pilot chamber 64 and switching the valve 62 to the arm-side merging position 62b, the oil discharged from the third hydraulic pump P3 and the oil discharged from the second hydraulic pump P2 are merged. Is increased.

  On the other hand, when the pilot pressure is supplied to the pilot chamber 44 of the bucket control valve 40 and the bucket control valve 40 is switched to the second drive position 40c that operates the bucket 30 in the opening direction, the pilot pressure is Switched to the pilot chamber 69 of the switching valve 67, the valve 67 is switched to the pilot pressure release position 67b, and the pilot line 68 leading to the pilot chamber 64 is directly connected to the tank. The valve 62 is maintained at the merge blocking position 62a, and the discharge oil is not merged. That is, the speed of the arm cylinder 34 is not increased. As a result, it is possible to smoothly perform a sediment discharge operation that requires cooperation between the arm pushing operation and the bucket opening operation.

  A fourth embodiment is shown in FIGS. The apparatus according to this embodiment electrically performs switching control of the merging switching valve 62.

  In FIG. 5, a pilot pressure release line 73 branches from a pilot line 68 leading to the pilot chamber 64 of the merging switching valve 62 to reach a tank, and an electromagnetic switching valve 80 is provided in the middle thereof. The electromagnetic switching valve 80 maintains an open position 80a for opening the pilot pressure release line 73 when the solenoid 81 is not excited, while a cutoff position for cutting off the pilot pressure release line 73 when the solenoid 81 is excited. It can be switched to 80b.

  On the other hand, pressure switches 82 and 84 are provided on the pilot lines communicating with the pilot chambers 52 and 54 of the arm control valve 50, respectively. These pressure switches 82 and 84 are normally open switches, and the contacts are closed only when a pilot pressure exceeding a certain level is generated in the pilot line in which the switches are provided.

  A pressure switch 86 is also provided in a pilot line that leads to the pilot chamber 44 of the bucket control valve 40 (a pilot chamber for switching the bucket control valve 40 to the second drive position 40c). The pressure switch 86 is a normally closed switch, and the contact is opened only when a pilot pressure exceeding a certain level is generated in the pilot line in which the switch is provided.

  FIG. 6 shows a circuit for controlling energization of the solenoid 81. In the figure, a solenoid drive line 91 and an energization control line 92 are arranged in parallel between the positive electrode of the power supply 90 and the ground.

  A relay contact 96 of the relay 94 and the solenoid 81 are arranged in series on the solenoid drive line 91, and the solenoid 81 is energized and excited only when the relay contact 96 is closed.

  In the energization control line 92, the pressure switch 86, the pressure switch 82, and the relay coil 98 of the relay 94 are arranged in series, and the pressure switch 84 is arranged in parallel with the pressure switch 82. A merging restriction release switch 88 is provided in parallel with the pressure switch 86. The merge restriction release switch 88 is provided in the driver's seat, and is switched from an open state to a closed state by switch operation.

  In a state in which the merging restriction release switch 88 is open, pilot pressure is supplied to one of the pilot chambers 52 and 54 of the arm control valve 50, and the control valve 50 is operated to one of the drive positions 50b and 50c. Then, one of the pressure switches 82 and 84 is closed.

  At this time, if the pilot pressure is not supplied to the pilot chamber 44 of the bucket control valve 40 (that is, if the bucket control valve 40 is in the neutral position 40a or the first drive position 40b), the pressure switch 86 is in a closed state. Then, a current flows through the energization control line 92, the relay coil 98 is energized, the relay contact 96 is closed, and the solenoid 81 is energized (excited). As a result, the electromagnetic switching valve 80 is switched from the open position 80a to the blocking position 80b, the pilot pressure release line 73 is blocked, and the pilot pressure is supplied from the pilot pump P4 to the pilot chamber 64 of the merging switching valve 62. The valve 62 is switched to the arm side joining position 62b to join the discharge oil of the third hydraulic pump P3 to the primary side of the arm control valve 50. That is, the speed of the arm cylinder 34 is increased.

  On the other hand, when the pilot pressure is supplied to the pilot chamber 44 of the bucket control valve 40 and the bucket control valve 40 is switched to the second drive position 40c, that is, the position to rotate the bucket 30 in the opening direction, the pilot Since the pressure switch 86 is opened by the pressure and the energization control line 92 is cut off, the relay coil 98 is de-energized and the relay contact 96 is opened. That is, the solenoid 81 is not energized, and the electromagnetic switching valve 80 is maintained at the open position 80a that opens the pilot pressure release line 73. Therefore, no pilot pressure is supplied to the pilot chamber 64 of the merging switching valve 62, and the valve 62 Holds the merge blocking position 62a. Accordingly, at this time, the discharge oil of the third hydraulic pump P3 is not joined to the arm side.

  However, at this time, if the merge restriction release switch 88 is operated and the switch is closed, the relay coil 98 is energized to close the relay contact 96 regardless of whether the pressure switch 86 is opened or closed. 80 is switched to the cutoff position 80b, and the merging switching valve 62 is switched to the arm side merging position 62b. Therefore, in this case, the oil discharged from the third hydraulic pump P3 can be merged with the arm control valve 50 (that is, the arm-side merge regulating operation is released).

  As such switching control of the electromagnetic switching valve 80, program control by a microcomputer may be executed instead of using a circuit as shown in FIG.

  In any of the above-described embodiments, the merging switching valve 62 is held at the merging / blocking position 62a as the arm-side merging restriction operation. However, the arm-side merging restriction operation does not completely block the merging, but the merging flow rate. May be reduced.

  An example thereof is shown in FIG. 7 as a fifth embodiment. Here, the center bypass flow path 61 on the third hydraulic pump P3 side increases as the operation stroke of the junction switching valve 62 of the apparatus shown in FIG. 3 increases from the junction blocking position 62a to the arm side junction position 62b. To the arm control valve 50 through the merging flow path 65 is constituted by a flow rate control valve that increases the merging flow rate of the hydraulic oil. That is, the merging switching valve 62 according to this embodiment restricts only a part of the hydraulic oil from the center bypass passage 61 between the merging cutoff position 62a and the complete arm side merging position 62b. Thus, a merging suppression position 62c that diverges to the arm-side merging oil passage 65 side is provided.

  On the other hand, the pilot pressure release line 72 is provided with a throttle 77, and when the pilot switching valve 74 is switched to the open position 74b for opening the pilot pressure release line 72, the pilot line 68 changes to the pilot pressure release line 72. The flow rate of the flowing hydraulic oil is suppressed by the amount of the throttle 77. As a result, the pilot pressure is lower than when the pilot pressure release line 72 is shut off from the pilot line 68 to the pilot chamber 64 of the merging switching valve 62. Thus, the merging switching valve 62 is switched to the merging suppression position 62c.

  In this apparatus, when the arm control valve 50 is operated to the first drive position 50b or the second drive position 50c and the bucket control valve 40 is operated to the neutral position 40a or the first drive position 40b, the arm side The slave valve 58 is switched to the shut-off position 58b or 58c that shuts off the pilot pressure release line 70, and the pilot switching valve 74 keeps the shut-off position 74a and shuts off the pilot pressure release line 72. The maximum pilot pressure is supplied to 64, and the valve 62 is switched to the arm side joining position 62b. Therefore, the entire amount of hydraulic fluid flowing from the third hydraulic pump P3 to the merging switching valve 62 through the center bypass flow passage 61 is merged with the hydraulic fluid supplied from the second hydraulic pump P2 to the arm control valve 50 through the arm-side merging oil passage 65. To do. Thereby, the operating speed of the arm cylinder 34 is fully increased.

  On the other hand, when the arm control valve 50 is operated and the bucket control valve 40 is switched to the second drive position 40c, that is, the position for operating the bucket 30 in the opening direction, the pilot switching valve 74 is opened. As a result of switching to 74b and opening the pilot pressure opening line 72, the pilot pressure supplied to the pilot chamber 64 is lower than when the pilot switching valve 74 is in the shut-off position 74a. Therefore, only a part of the hydraulic fluid flowing through the center bypass passage 61 is arm-side merged because the operation stroke is suppressed and the operation is switched to the merge suppression position 62c between the merge blocking position 62a and the arm-side merge position 62b. The oil passage 65 is diverted at a low flow rate. Accordingly, in this case as well, the operating speed of the arm cylinder 34 is increased, but the increase in speed is suppressed, and a good balance between the operating speed of the arm cylinder 34 and the operating speed of the bucket cylinder 36 is maintained.

  According to such a configuration, at the time of earth and sand discharge operation, the arm cylinder 34 is not completely stopped from speeding up. It is possible to set the operating speed.

  Here, the means for adjusting the operation stroke of the merging switching valve 62 is not limited to adjusting the pilot pressure to the pilot chamber 64 as described above, but may limit the stroke mechanically. Good.

  An example thereof is shown in FIG. 8 as a sixth embodiment. In this embodiment, a cylinder driving oil passage 100 is branched from a pilot line 68 that extends from the pilot pump P4 to the pilot chamber 64 of the merging switching valve 62, and the cylinder driving oil passage 100 is connected to the stroke limiting cylinder 102. Head side room is connected. The stroke limiting cylinder 102 is attached to the merging switching valve 62. In the contracted state, the stroke limiting cylinder 102 allows a full stroke from the merging cutoff position 62a of the merging switching valve 62 to the arm side merging position 62b, while the cylinder 102 When hydraulic oil is supplied to the head side chamber and extends, the stroke from the joining block position 62a to the arm side joining position 62b is restricted and stopped at the middle joining position 62c.

  On the other hand, a drive release oil passage 104 branches from the cylinder drive oil passage 100 to the tank side, and a bucket side valve 48 connected to the bucket control valve 40 is provided in the middle of the drive release oil passage 104. Is provided. When the bucket control valve 40 is in the neutral position 40a or the first drive position 40b, the bucket side child valve 48 is switched to open positions 48d and 48e that open the drive release oil passage 104, while the bucket When the control valve 40 is switched to the second drive position 40c, the control valve 40 is interlocked with the bucket control valve 40 so as to be switched to the cutoff position 48f that shuts off the drive release oil passage 104.

  In this apparatus, when the bucket control valve 40 is in the neutral position 40a or the first drive position 40b, the bucket side child valve 48 is switched to the open position 48d or the open position 48e to open the drive release oil passage 104. All of the hydraulic oil flowing into the cylinder driving oil passage 100 from the pilot pump P4 is released to the tank through the driving release oil passage 104, and the stroke limiting cylinder 102 is not driven (ie, is not extended). Therefore, when the arm side valve 58 is switched to the shut-off position 58b or the shut-off position 58c by operating the arm control valve 50 in this state and the pilot pressure is supplied to the pilot chamber 64 of the merging switching valve 62, the merging switching is performed. The valve 62 is operated for a full stroke from the merge blocking position 62a to the arm side merge position 62b, and guides the entire amount of hydraulic oil flowing from the third hydraulic pump P3 through the center bypass flow path 61 to the merge oil path 65 to the arm side.

  On the other hand, when the bucket control valve 40 is switched to the second drive position 40c, the bucket side valve 48 is switched to the cutoff position 48f and shuts off the drive release oil passage 104, so that the pilot pump P4 drives the cylinder. The hydraulic oil flowing into the oil passage 100 is supplied to the head side chamber of the stroke limiting cylinder 102 and the cylinder 102 extends. Since the stroke of the merging switching valve 62 is limited by the extension of the stroke limiting cylinder 102, even if the pilot pressure is supplied to the pilot chamber 64 of the merging switching valve 62 by the operation of the arm control valve 50, the merging switching valve 62 is A full stroke is not possible from the merge blocking position 62a to the arm side merge position 62b, but only a stroke to the middle merge suppression position 62c is stopped. Therefore, only a part of the hydraulic oil flowing from the third hydraulic pump P3 through the center bypass passage 61 is supplied to the arm-side joining oil passage 65 side, and the speed increase of the arm cylinder 34 is suppressed accordingly.

  In the apparatus shown above, a. The arm control valve 50 is operated from the neutral position 50a to the first drive position 50b side or the second drive position 50c side by a certain amount or more; b. The arm side merging restricting operation is performed only on the condition that the bucket control valve 40 is operated to the second drive position 40c side (bucket opening operation side). It is generally performed at the same time, and the operation of overturning the boom 26 may be added to the conditions for executing the arm side merging restriction operation.

  An example thereof is shown in FIG. 9 as a seventh embodiment. This figure shows a boom control valve 110 that drives the boom cylinder 32 by receiving the hydraulic pressure supply from the first hydraulic pump P1 together with the bucket control valve 40 in the apparatus shown in FIG.

  The boom control valve 110 is also constituted by a three-position pilot switching valve, similar to the bucket control valve 40, and is provided at a position upstream of the bucket control valve 40 in the center bypass passage 46. When the pilot pressure is not supplied to any of the pilot chambers 112 and 114, the neutral position 110a for flowing all the discharged oil of the first hydraulic pump P1 to the center bypass passage 46 is held, while the pilot chamber 112 When the pilot pressure is supplied, the center bypass flow path 46 is closed and the discharge oil is guided to the head side chamber of the boom cylinder 32 to switch to the first drive position 110b where the boom 26 is raised. When pilot pressure is supplied to the pilot chamber 114, the center bypass flow path 46 is closed and the discharge oil is guided to the rod side chamber of the boom cylinder 32 so as to be switched to the second drive position 110c that causes the boom 26 to fall. It is configured.

  Further, as a feature of this device, a boom side child valve 118 linked to the boom control valve 110 is connected to the boom control valve 110, and the boom side child valve 118 is in series with the bucket side child valve 48 in the pilot pressure release line 72. Is provided. As with the bucket side valve 48, the boom side child valve 118 is cut off positions 118a, 118b that cut off the pilot pressure release line 72 when the boom control valve 110 is in the neutral position 110a or the first drive position 110b. On the other hand, when the boom control valve 110 is switched to the second drive position 110c, the boom control valve 110 is switched to the opening position 118c for opening the pilot pressure release line 72.

  According to this configuration, the arm control valve 50 is switched to the first driving position 50b or the second driving position 50c, and the arm side child valve 58 is switched to the blocking position 58b or the blocking position 58c where the pilot pressure release line 70 is blocked. Where a. The bucket control valve 40 is switched to the second drive position 40c for operating the bucket 30 in the opening direction, and the bucket side valve 48 is switched to the opening position 48c; and b. Only when the boom control valve 110 is switched to the second drive position 110c that operates the boom 26 in the inclining direction and the boom side sub valve 118 is switched to the open position 118c, the pilot pressure release line 72 is opened and the merging is switched. The operation of canceling the pilot pressure applied to the pilot chamber 64 of the valve 62, that is, the arm side merging restriction operation is executed.

  An eighth embodiment is shown in FIG. In the apparatus according to this embodiment, when the arm side merge restriction operation is performed, the discharge oil of the third hydraulic pump P3 is further merged with the primary side of the bucket control valve 40 to increase the speed of the bucket cylinder 36. Bucket-side merging operation is performed.

  Specifically, the apparatus shown in FIG. 10 is provided with a merging switching valve 120 including a three-position pilot switching valve in place of the merging switching valve 62 in the apparatus shown in FIG. The merging switching valve 120 includes a merging cutoff position (neutral position) 120a through which the hydraulic oil flowing from the third hydraulic pump P3 through the center bypass passage 61 is released to the tank, and the hydraulic oil through the arm-side merging oil passage 65. In addition to the arm-side merging position 120b that leads to the primary port of the arm control valve 50, there is a bucket-side merging position 120c that leads to the bucket-side merging oil passage 126 while restricting the flow of part of the hydraulic oil. Here, the bucket-side merging oil passage 126 is connected to a supply oil passage from the first hydraulic pump P1 to the bucket control valve 40, and the hydraulic oil guided to the merging oil passage 126 is the first hydraulic pump. The hydraulic oil supplied to the bucket control valve 40 from P1 is joined.

  Of the pilot chambers 122 and 124 provided in the merging switching valve 120, the pilot chamber 122 for switching the valve 120 to the arm-side merging position 120b is connected to the pilot line 68 in the same manner as the apparatus shown in FIG. On the other hand, the pilot chamber 124 for switching the valve 120 to the bucket-side merging position 120 c is provided through the pilot line 128 that branches from the pilot line 68 at a position upstream of the throttle 66 of the pilot line 68. Connected to P4.

  The pilot line 128 has a throttle 127 in the middle thereof, and in the region downstream of the throttle 127 (on the pilot chamber 124 side), the pilot pressure releasing line 130 and the pilot pressure releasing line 132 from the pilot line 128. And each branch to the tank.

  On the other hand, the arm side valve 58 of the arm control valve 50 is provided in the middle of a pilot pressure release line 70 branched from the pilot line 68 as in the device shown in FIG. It is provided in the middle of the line 130 and is configured to open and close the line 130. Specifically, when the arm control valve 50 is in the neutral position 50a, the arm side child valve 58 maintains a position 58d where both the pilot pressure release lines 70 and 130 are opened. When switched to the first drive position 50b or the second drive position 50c, the pilot pressure release lines 70 and 130 are both switched to positions 58e and 58f.

  Further, the bucket side valve 48 of the bucket control valve 40 is provided in the middle of the pilot pressure release line 72 branched from the pilot line 68 in the same manner as the apparatus shown in FIG. It is provided in the middle of the line 132 so as to open and close the line 132. Specifically, when the bucket control valve 40 is in the neutral position 40a or the first drive position 40b, the bucket side child valve 48 shuts off the pilot pressure release line 72 and opens the pilot pressure release line 132. The positions 48g and 48h are maintained, respectively, and when the bucket control valve 40 is switched to the second drive position 40c, the pilot pressure release line 72 is opened and the pilot pressure release line 132 is switched to the position 48i. Has been.

  Next, the operation of this apparatus will be described.

  First, when the arm control valve 50 is not operated and is in the neutral position 50a, the arm side valve 58 is in a position 58d where both of the pilot pressure release lines 70 and 130 are opened. , 130, both pilot lines 68 and 128 communicate with the tank. Accordingly, no pilot pressure is generated in the pilot lines 68 and 128, and no pilot pressure is supplied to any of the pilot chambers 122 and 124 of the merging switching valve 120. Therefore, the valve 120 maintains the merging cutoff position 120a, The hydraulic oil flowing out from the turning control valve 60 from the third hydraulic pump P3 through the center bypass passage 61 is directly released to the tank.

  On the other hand, when the arm control valve 50 is operated from the neutral position 50a to the first drive position 50b or the second drive position 50c, the arm side child valve 58 blocks both pilot pressure release lines 70 and 130. It is switched to position 58b or 58c. At this time, the bucket control valve 40 is switched to the neutral position 40a or the first drive position 40b (position where the discharge oil of the first hydraulic pump P1 is guided to the head side chamber of the bucket cylinder 36 and the bucket 30 is moved in the closing direction). If this is the case, the bucket side valve 48 is switched to the position 48a or 48b where the pilot pressure release line 72 is shut off and the pilot pressure release line 132 is opened, so that the pilot line 128 connected to the pilot pressure release line 132 (details) The pilot pressure of the pilot line 128 on the downstream side of the throttle 127) is released, but since the pilot pressure release lines 70 and 72 are both shut off, the pilot line 68 has a pilot pressure. Is left and supplied to the pilot chamber 122 of the merging switching valve 120.As a result, the merging switching valve 120 is switched to the arm-side merging position 120b, and the hydraulic oil flowing from the third hydraulic pump P3 through the center bypass passage 61 is guided to the arm-side merging oil passage 65, and the second hydraulic pump P2 The hydraulic oil supplied to the control valve 50 is merged. Thereby, the operating speed of the arm cylinder 34 is increased.

  On the other hand, when the bucket control valve 40 is switched to the second drive position 40c, the bucket side valve 48 shuts off the pilot pressure release line 132 and opens the pilot pressure release line 72. Therefore, even if the arm control valve 50 is operated from the neutral position 50a to the first drive position 50b or the second drive position 50c, the pilot line 68 connected to the pilot pressure release line 72 (specifically, the pilot line 68 The pilot pressure in the line downstream of the throttle 66) is eliminated, but the pilot pressure elimination lines 130 and 132 are both shut off, so the pilot pressure remains in the pilot line 128 and the merge switching valve 120 Pilot pressure is supplied to the pilot chamber 124. As a result, the merging switching valve 120 is switched to the bucket-side merging position 120c, and the hydraulic oil flowing from the third hydraulic pump P3 through the center bypass passage 61 is guided to the bucket-side merging oil passage 126 at a regulated flow rate. The hydraulic oil supplied from the hydraulic pump P1 to the bucket control valve 40 is joined. Therefore, in addition to stopping the acceleration of the arm cylinder 34, the operation speed of the bucket cylinder 36 is moderately increased by the amount of the merge, thereby maintaining a speed balance for smoothly performing the sediment discharge operation and the like. It will be.

  Also in this apparatus, as in the arm side merging restriction condition in the apparatus shown in FIG. 9, as a condition for performing the bucket side merging, in addition to the operation of the arm 28 and the operation in the opening direction of the bucket 30, It may be added to be manipulated. In that case, as shown in FIG. 11 as the ninth embodiment, the positions of the bucket control valves 40 aligned in series with the bucket side valve 48 in the pilot pressure release lines 72 and 132 of the apparatus shown in FIG. The boom side sub-valve 118 interlocked with the boom side control valve 110 may be disposed in the main valve 118, and the sub-valve 118 may have the same opening / closing function as the bucket side sub-valve 48.

  That is, when the boom control valve 110 is switched to the neutral position 110a or the first drive position 110b for raising the boom 26, the boom side sub-valve 118 opens the pilot pressure release line 132 and opens the pilot pressure release line 72. When switching to the shut-off position 118d (or 118e) and the boom control valve 110 is switched to the second drive position 110c that causes the boom 26 to fall down, the boom side slave valve 118 shuts off the pilot pressure release line 132 and The pilot pressure release line 72 may be switched to the position 118f that opens.

  Alternatively, as the arm merging restriction operation, the discharge oil of the third hydraulic pump P3 may be distributed at a flow rate restricted to both the arm side and the bucket side and merged with each other. In that case, the junction switching valve 120 shown in FIG. 10 may be configured as shown in FIG.

  The merging switching valve 120 shown in FIG. 12 is a merging cutoff position for allowing hydraulic oil flowing from the third hydraulic pump P3 through the center bypass passage 61 to the tank as it is when pilot pressure is not supplied to both pilot chambers 122 and 124. (Neutral position) When the pilot pressure is supplied to the pilot chamber 122 while maintaining 120d, the hydraulic oil from the center bypass passage 61 is switched to the arm side joining position 120e that leads to the arm side joining oil passage 65. When the pilot pressure is supplied to the pilot chamber 124 (that is, when the arm control valve 50 shown in FIG. 10 is operated and the bucket control valve 40 is operated to the second drive position 40c), the center bypass flow is performed. The hydraulic oil from the passage 61 is divided into the arm side joining oil passage 65 and the bucket side joining oil passage 126. It is adapted to be switched to the bucket-side junction position 120f.

1 is a hydraulic circuit diagram showing a hydraulic pressure supply device for a hydraulic excavator according to a first embodiment of the present invention. FIG. 2 is an overall configuration diagram of the hydraulic excavator. It is a hydraulic circuit diagram which shows the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 2nd Embodiment of this invention. It is a hydraulic circuit diagram which shows the principal part of the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 3rd Embodiment of this invention. It is a hydraulic circuit diagram which shows the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 4th Embodiment of this invention. It is an electric circuit diagram which shows the control circuit of the electromagnetic switching valve provided in the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 4th Embodiment of this invention. It is a hydraulic circuit diagram which shows the principal part of the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 5th Embodiment of this invention. It is a hydraulic circuit diagram which shows the principal part of the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 6th Embodiment of this invention. It is a hydraulic circuit diagram which shows the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 7th Embodiment of this invention. It is a hydraulic circuit diagram which shows the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 8th Embodiment of this invention. It is a hydraulic circuit diagram which shows the principal part of the hydraulic pressure supply apparatus of the hydraulic shovel which concerns on the 9th Embodiment of this invention. It is a hydraulic circuit diagram which shows the modification of the confluence switching valve in the hydraulic pressure supply apparatus of the hydraulic shovel shown in FIG. (A)-(c) is a figure which shows the motion of the boom, an arm, and a bucket in the earth-and-sand discharge | release operation of a hydraulic shovel.

Explanation of symbols

P1 1st hydraulic pump P2 2nd hydraulic pump P3 3rd hydraulic pump P4 Pilot pump 10 Hydraulic excavator 26 Boom 28 Arm 30 Bucket 32 Boom cylinder (actuator for boom drive)
34 Arm cylinder (actuator for arm drive)
36 Bucket cylinder (bucket drive actuator)
40 Bucket control valve 48 Bucket side valve (confluence control means)
50 Arm control valve 58 Arm side child valve (Merging control means)
62 Junction switching valve 62a Junction blocking position 62b Arm side merging position 62c Junction suppression position 65 Arm side merging oil passage 67 Pilot switching valve (merging control means)
68 Pilot line (Meeting control means)
70, 72 Pilot pressure release line (Merge control means)
74 Pilot switching valve (confluence control means)
76 Electromagnetic switching valve (Meeting restriction release means)
80 Electromagnetic switching valve (confluence control means)
82, 84, 86 Pressure switch (confluence control means)
88 Merge restriction release switch 90 Power supply 94 Relay (Merge control means)
102 Stroke restriction cylinder 110 Boom control valve 118 Boom side child valve (joining control means)
120 Merge switching valve 120a, 120d Merge blocking position 120b, 120e Arm side merge position 120c, 120f Bucket side merge position

Claims (7)

  An arm drive actuator that rotates an arm attached to a boom that can be raised and lowered with respect to the airframe in an up-and-down direction with respect to the boom, and a bucket attached to the tip of the arm is turned up and down with respect to the arm. An apparatus for supplying hydraulic pressure to both actuators of a hydraulic excavator provided with a bucket drive actuator to be provided, and provided between a first hydraulic pump and the first hydraulic pump and the bucket drive actuator. And having a neutral position for blocking between the first hydraulic pump and the bucket driving actuator, and operating from the neutral position to guide the hydraulic oil from the first hydraulic pump to the bucket driving actuator. The bucket control valve to be switched, the second hydraulic pump, the second hydraulic pump and the A neutral position between the second hydraulic pump and the arm driving actuator, and is operated from the neutral position to operate the second hydraulic pump from the second hydraulic pump. An arm control valve that is switched to a state in which hydraulic oil is guided to the arm driving actuator, a third hydraulic pump that supplies hydraulic pressure to a hydraulic actuator different from the bucket driving actuator and the arm driving actuator, and the third hydraulic pump A merging switching valve that is switched between an arm-side merging position for joining the discharged oil to the hydraulic oil supplied to the arm control valve from the second hydraulic pump and a merging blocking position for blocking the merging, and the arm control valve When in the neutral position, the merging switching valve is switched to the merging cutoff position, and the arm control valve While performing a merging switching operation for switching the merging switching valve to the arm-side merging position when operated more than a certain amount from the neutral position, even if the arm control valve is operated more than a certain amount from the neutral position A merging control means for performing an arm side merging restriction operation for reducing a merging flow rate of hydraulic oil from the third hydraulic pump to the arm control valve when the bucket control valve is operated in a direction to rotate the bucket in the opening direction; A hydraulic supply device for a hydraulic excavator, comprising:   The hydraulic supply device for a hydraulic excavator according to claim 1, wherein the hydraulic excavator is provided between the first hydraulic pump and a boom driving actuator for raising and lowering the boom, and between the first hydraulic pump and the boom driving actuator. A boom control valve having a neutral position to be shut off and being operated from the neutral position to be switched to a state in which hydraulic fluid is guided from the first hydraulic pump to the boom drive actuator; and the merging control means includes the arm When the control valve is operated more than a certain amount from its neutral position, the bucket control valve is operated to rotate the bucket in the bucket opening direction, and the boom control valve is operated to tilt the boom The hydraulic excavator oil performs the arm side merge restriction operation only when Supply device.   3. The hydraulic pressure supply device for a hydraulic excavator according to claim 1 or 2, wherein the arm side merging restricting operation sets the merging switching valve to the merging cutoff position even if the arm control valve is operated more than a certain amount from its neutral position. A hydraulic supply device for a hydraulic excavator, characterized in that the operation is performed.   3. The hydraulic pressure supply device for a hydraulic excavator according to claim 1 or 2, wherein the merging switching valve operates from the third hydraulic pump to the arm control valve as the operation stroke from the merging / blocking position to the arm side merging position increases. This is a flow control valve that increases the combined flow rate of oil, and the arm side combined flow restricting operation reduces the operation stroke amount of the combined switching valve from the combined blocking position compared to when the bucket control valve is not operated. A hydraulic supply device for a hydraulic excavator, characterized in that it exists.   5. The hydraulic pressure supply device for a hydraulic excavator according to claim 1, wherein the merging control means uses the first hydraulic pump to discharge oil from the third hydraulic pump when performing the arm-side merging restriction operation. 6. A hydraulic supply device for a hydraulic excavator, which performs a bucket-side merging switching operation for merging with hydraulic oil supplied to the bucket control valve from   6. The hydraulic pressure supply device for a hydraulic excavator according to claim 5, wherein the merging switching valve controls the bucket oil from the first hydraulic pump from the first hydraulic pump in addition to the merging cutoff position and the arm side merging position. A bucket-side merging position for merging with the hydraulic oil supplied to the valve, and the merging control means performs an operation of switching the merging switching valve to the bucket-side merging position as the bucket-side merging switching operation. A hydraulic supply device for a hydraulic excavator.   The hydraulic pressure supply device for a hydraulic excavator according to any one of claims 1 to 6, wherein a cancellation command input means for inputting a command to cancel the arm side merging restriction operation of the merging control means, and the cancellation command input means A hydraulic pressure supply device for a hydraulic excavator, comprising: merge restriction release means for releasing an arm side merge restriction operation of the merge control means when the command is input.

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