JP6909115B2 - Hydraulic excavator - Google Patents

Description

The present invention relates to a hydraulic excavator including a working device including a boom, an arm and a bucket, and a plurality of hydraulic actuators for moving the working device.

Conventionally, there is known a hydraulic excavator as described above, which is provided with a plurality of hydraulic pumps for driving the plurality of hydraulic actuators. For example, Patent Document 1 describes a plurality of hydraulic actuators including a boom cylinder, an arm cylinder, a bucket cylinder, and a swivel motor, and three hydraulic pumps for supplying hydraulic oil to the plurality of hydraulic actuators. A hydraulic excavator with 2nd and 3rd pumps is disclosed.

The hydraulic excavator further includes a boom control valve, an arm control valve, a bucket control valve, and a swivel control valve, which are a plurality of control valves for controlling the drive of each of the hydraulic actuators. These control valves are pilot-operated switching valves that open in conjunction with the operations given to the boom lever, arm lever, bucket lever, and swivel lever. Specifically, the first pump is connected to the boom cylinder via the boom control valve and is connected to the bucket cylinder via the bucket control valve. Further, the second pump is connected to the arm cylinder via the arm control valve and is connected to the swivel motor via the swivel control valve.

Further, the hydraulic excavator includes a boom merging valve and an arm merging valve for accelerating the movement of the boom and the arm as needed. The boom merging valve is interposed between the second pump and the boom cylinder, and is opened by receiving an input of a valve opening command for speed increase from the controller, and the boom cylinder is opened from the second pump. Allows the merging of hydraulic fluid into. The arm merging valve is interposed between the third pump and the arm cylinder, and is opened by receiving an input of a valve opening command for speed increase from the controller, and the arm cylinder is opened from the third pump. Allows the merging of hydraulic fluid into.

Japanese Unexamined Patent Publication No. 2014-190137

The hydraulic excavator described in Patent Document 1 has the following problems to be solved.

(A) Energy loss during excavation work In the hydraulic excavator, excavation work is performed by combining a boom raising operation due to the extension of the boom cylinder, an arm pulling operation due to the extension of the arm cylinder, and a bucket excavation operation due to the extension of the bucket cylinder. Will be done. At this time, since the bucket cylinder moves the bucket in the excavation direction against the excavation reaction force that the bucket receives from the ground, the load for driving the bucket cylinder is large, and thus the bucket cylinder is supplied from the first pump to the bucket cylinder. The pressure of the hydraulic fluid increases. On the other hand, since the excavation reaction force acts on the boom in the direction of lifting it, the load for driving the boom cylinder is low, so that the pressure of the hydraulic oil supplied from the first pump to the boom cylinder is also high. On the contrary, it becomes low. As a result, the front-rear differential pressure of the boom control valve interposed between the first pump and the boom cylinder increases, and the pressure loss in the boom control valve, that is, the energy loss increases accordingly.

(B) Speeding up of bucket drive In the hydraulic excavator, the movement of the boom and the arm can be accelerated by opening the boom merging valve and the arm merging valve, but the movement of the bucket cannot be accelerated. Therefore, it cannot be expected that the work efficiency will be improved by the speed increase.

An object of the present invention is to provide a flood control excavator capable of accelerating the movement of a bucket with less energy loss during excavation work.

The provided hydraulic excavator is rotatably connected to a runnable base machine, an undulating boom, an arm rotatably connected to the tip of the boom, and the tip of the arm. A bucket, a boom hydraulic actuator that operates to raise and lower the boom by receiving the supply of hydraulic oil, and an arm hydraulic actuator that operates to rotate the arm with respect to the boom by receiving the supply of hydraulic oil. An actuator, a bucket hydraulic actuator that operates to rotate the bucket with respect to the arm by receiving the supply of hydraulic oil, and a boom hydraulic actuator and the bucket hydraulic actuator that are hydraulic pumps that discharge hydraulic oil. A first pump that can be connected to, a second pump that discharges hydraulic oil and can be connected to the arm hydraulic actuator, and a hydraulic pump that discharges hydraulic oil. A third pump that can be connected to the bucket hydraulic actuator, a boom operating member that receives a boom operation to move the boom hydraulic actuator, and an arm operating member that receives an arm operation to move the arm hydraulic actuator. From the first pump, the bucket operating member that receives the bucket operation for moving the bucket hydraulic actuator is interposed between the first pump and the boom hydraulic actuator, and the valve is opened in response to the boom operation. From the second pump, the boom control valve that controls the supply of hydraulic oil to the boom hydraulic actuator is interposed between the second pump and the arm hydraulic actuator, and the valve is opened in response to the arm operation. From the third pump, the arm control valve that controls the supply of hydraulic oil to the arm hydraulic actuator is interposed between the third pump and the bucket hydraulic actuator, and the valve is opened in response to the bucket operation. The bucket control valve that controls the supply of hydraulic oil to the bucket hydraulic actuator is interposed between the first pump and the bucket hydraulic actuator, and the valve is opened only when a valve opening command is received. A bucket merging valve that allows the hydraulic oil discharged by the pump to join the hydraulic oil supplied from the third pump to the bucket hydraulic actuator, and an excavation operation by the bucket that involves rotation of the arm in the pulling direction. The excavation operation is detected by the excavation state detection unit that detects the presence or absence and the excavation state detection unit. If not, the bucket merging valve is given the opening command in response to the bucket operation to open the bucket merging valve, and when the excavation state detection unit detects the excavation operation, the bucket operation is performed. Regardless of the above, the bucket merging control device is provided, which prohibits the merging through the bucket merging valve without giving the valve opening command to the bucket merging valve.

In this hydraulic excavator, the first, second and third pumps are connected to the boom hydraulic actuator, the arm hydraulic actuator and the bucket hydraulic actuator via the boom control valve, the arm control valve and the bucket control valve, respectively. In addition to functioning as a main drive pump that drives the arm and bucket, respectively, the first pump also functions as a bucket acceleration pump by being connected to the bucket hydraulic actuator via a bucket merging valve. be able to.

Moreover, the bucket merging control device of the hydraulic excavator is involved in the bucket operation given to the bucket operating member when the excavation determination unit determines that the excavation operation is performed by the bucket accompanied by the movement of the arm in the pulling direction. By prohibiting the opening of the bucket merging valve, the energy loss during the excavation operation can be effectively reduced. When the excavation operation is being performed, the bucket receives an excavation reaction force from the ground, so that the drive load of the bucket hydraulic actuator for moving the bucket increases and the pressure of the hydraulic oil supplied to the bucket hydraulic actuator increases. On the other hand, the drive load of the boom hydraulic actuator connected to the first pump is reduced by the amount that the excavation reaction force acts as an upward force on the boom, and the pressure of the hydraulic oil supplied to the boom hydraulic actuator is low. Therefore, if the bucket merging valve is opened and the first pump is communicated with the bucket hydraulic actuator, the discharge pressure of the first pump becomes high and the front-rear differential pressure of the boom control valve becomes large. Energy loss will increase. Therefore, during such an excavation operation, it is possible to shut off the first pump from the bucket hydraulic actuator by prohibiting the merging through the bucket merging valve regardless of the operation given to the bucket operating member, so that the discharge pressure of the first pump is remarkable. It is possible to prevent the rise and suppress the increase in the energy loss caused by the rise.

Moreover, since the bucket is not required to move very quickly in the excavation operation, even if the speed increase of the bucket movement due to the opening of the bucket merging valve is prohibited, the influence on the work efficiency is small.

On the other hand, when the excavation determination unit determines that the excavation operation has not been performed, the bucket merging control device appropriately opens the bucket merging valve according to the bucket operation given to the bucket operating member, and the first pump. By allowing the hydraulic oil to merge into the bucket cylinder, it is possible to accelerate the movement of the bucket as needed (for example, the movement of the bucket in the opening direction opposite to the excavation direction).

The hydraulic excavator is interposed between the first pump and the arm hydraulic actuator, and the hydraulic oil discharged from the first pump is discharged from the second pump by opening the valve only when a valve opening command is received. An arm merging valve that allows merging with hydraulic oil supplied to the arm hydraulic actuator, and an arm merging valve that opens the arm merging valve in response to the arm operation when the excavation operation is not detected by the excavation operation detection unit. A command is given to open the arm merging valve, and when the excavation motion is detected by the excavation motion detection unit, the arm is not given the valve opening command to the arm merging valve regardless of the arm operation. It is preferable to further include an arm merging control device that prohibits the merging through the merging valve.

Similar to the bucket merging control device, the arm merging control device makes it possible to accelerate the movement of the arm using the first pump while effectively reducing the energy loss in the boom control valve during the excavation operation. .. Specifically, the arm merging control device prohibits the opening of the arm merging valve regardless of the arm operation when the excavation operation accompanied by the movement in the pulling direction of the arm is detected, and causes the arm hydraulic actuator to move. By shutting off from one pump, the energy loss of the boom control valve due to the difference between the operating pressure of the arm hydraulic actuator and the operating pressure of the boom hydraulic actuator during the excavation operation can be effectively reduced. On the other hand, when the excavation operation is not detected, the arm merging control device appropriately opens the arm merging valve in response to the arm operation to allow the merging of hydraulic oil from the first pump to the arm hydraulic actuator. By doing so, it is possible to accelerate the movement of the arm as needed (for example, the arm pushing operation or the arm pulling operation for leveling).

As described above, according to the present invention, there is provided a hydraulic excavator capable of moving a boom, an arm and a bucket at an appropriate speed even during a combined operation thereof without causing a significant pressure loss.

It is a front view which shows the whole structure of the hydraulic excavator which concerns on embodiment of this invention. It is a figure which shows the hydraulic circuit mounted on the hydraulic excavator which concerns on the said Embodiment. It is a block diagram which shows the functional structure of the controller which concerns on the said Embodiment. It is a flowchart which shows the bucket merging control performed by the controller. It is a flowchart which shows the 1st arm merging control performed by the controller. It is a graph which shows the characteristic of the bucket merging pilot pressure when it is judged that the excavation operation is not performed by the excavation determination part in the controller. It is a graph which shows the characteristic of the bucket merging pilot pressure when it is judged that the excavation operation is performed by the excavation determination part in the controller.

Preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the appearance of a hydraulic excavator according to an embodiment of the present invention. The hydraulic excavator includes a lower traveling body 7, an upper swivel body 8 mounted on the lower traveling body 7 so as to be able to swivel around the vertical axis, and a work attachment 10 mounted on the upper swivel body 8. The body 7 and the upper swivel body 8 form a base machine. The work attachment 10 is rotatably connected to a boom 12 undulatingly attached to the upper swing body 8, an arm 14 rotatably connected to the tip of the boom 12, and a tip of the arm 14. The bucket 16 is provided.

A boom cylinder 22 which is a boom hydraulic actuator, an arm cylinder 24 which is an arm hydraulic actuator, and a bucket cylinder 26 which is a bucket hydraulic actuator are mounted on the boom work attachment. These cylinders 22, 24, 26 are composed of hydraulic cylinders.

The boom cylinder 22 is interposed between the boom 12 and the upper swing body 8 so as to expand and contract by receiving the supply of hydraulic oil and rotate the boom 12 in the undulating direction. Specifically, the boom cylinder 22 moves the boom 12 in the boom raising direction (standing direction) indicated by the arrow 2A in FIG. 1 by extending, and conversely causes the boom 12 to move in FIG. 2 by contracting. Move in the boom lowering direction (falling direction) indicated by arrow 2B.

The arm cylinder 24 expands and contracts by receiving the supply of hydraulic oil, and is interposed between the arm 14 and the boom 12 so as to rotate the arm 14 around the horizontal axis with respect to the boom 12. Specifically, the arm cylinder 24 moves the arm 14 in the arm pulling direction indicated by the arrow 4A by extending, and conversely moves the arm 14 in the arm pushing direction indicated by the arrow 4B by contracting. ..

The bucket cylinder 26 expands and contracts by receiving the supply of hydraulic oil, and is interposed between the bucket 16 and the arm 14 so as to rotate the bucket 16 about the horizontal axis with respect to the arm 14. Specifically, the bucket cylinder 26 moves the bucket 16 in the bucket excavation direction indicated by the arrow 6A by extending, and conversely moves the bucket 16 in the bucket opening direction indicated by the arrow 6B by contracting. ..

FIG. 2 shows a hydraulic circuit mounted on a hydraulic excavator according to the first embodiment of the present invention. This hydraulic circuit is for driving a plurality of hydraulic actuators including the cylinders 22, 24, 26 and the swivel motor 28 which is a hydraulic motor for swiveling the upper swivel body 8. , A plurality of hydraulic pumps, a plurality of operating devices, a plurality of control valves, and a plurality of speed-increasing valves.

The plurality of hydraulic pumps include a first pump 31, a second pump 32, and a third pump 33. These are connected to the output shaft of a common engine 30 and driven by the engine 30. The first to third pumps 31 to 33 according to this embodiment are each composed of a variable displacement hydraulic pump.

The first pump 31 is connected in parallel to the boom cylinder 22, the arm cylinder 24, and the bucket cylinder 26 so as to be in charge of the main drive of the boom 12 and the acceleration of the arm 14 and the bucket 16. .. The second pump 32 is connected in parallel to the arm cylinder 24 and the boom cylinder 22 in order to take charge of the main drive of the arm 14 and the acceleration of the boom 12. The third pump 33 includes the bucket cylinder 26, the swivel motor 28, and the arm cylinder 24 so as to be in charge of the main drive of the bucket 16, the swivel drive of the upper swivel body 8, and the acceleration of the arm 14. Connected to. Although not shown in the drawings, the first pump 31 is connected to the left traveling motor via the left traveling control valve, and the second pump 32 is connected to the right traveling motor via the right traveling control valve. NS.

The plurality of operating devices include a boom operating device 42, an arm operating device 44, a bucket operating device 46, and a swivel operating device 48. Each of the operating devices 42, 44, 46, and 48 includes an operating lever that receives a rotation operation, a pilot valve that outputs a pilot pressure having a magnitude corresponding to the operating amount of the operating lever from a port corresponding to the operating direction, and a pilot valve. Has.

Specifically, the boom operating device 42 has a boom operating lever 42a and a boom pilot valve 42b connected to the boom operating lever 42a. The boom operating lever 42a functions as a boom operating member that receives a boom operation for moving the boom 12. The boom pilot valve 42b is a pilot pressure corresponding to the direction of the boom operation applied to the boom operation lever 42a among the boom raising pilot pressure and the boom lowering pilot pressure, and is the magnitude of the boom operation, that is, the boom operation amount. Outputs the boom pilot pressure of the corresponding size.

The arm operating device 44 has an arm operating lever 44a and an arm pilot valve 44b connected to the arm operating lever 44a. The arm operating lever 44a functions as an arm operating member that receives an arm operation for moving the arm 14. The arm pilot valve 44b is a pilot pressure corresponding to the direction of the arm operation given to the arm operation lever 44a among the arm pulling pilot pressure and the arm pushing pilot pressure, and corresponds to the magnitude of the arm operation, that is, the arm operation amount. Outputs the arm pilot pressure of the corresponding size.

The bucket operating device 46 has a bucket operating lever 46a and a bucket pilot valve 46b connected to the bucket operating lever 46a. The bucket operating lever 46a functions as a bucket operating member that receives a bucket operation for moving the bucket 16. The bucket pilot valve 46b is a pilot pressure corresponding to the direction of the bucket operation given to the bucket operation lever 46a among the bucket excavation pilot pressure and the bucket opening pilot pressure, and is the magnitude of the bucket operation, that is, the bucket operation amount. Outputs the bucket pilot pressure of the corresponding size.

The swivel operation device 48 has a swivel operation lever 48a and a swivel pilot valve 48b connected to the swivel operation lever 48a. The swivel operation lever 48a functions as a swivel operation member that receives a swivel operation for swiveling the upper swivel body 8. The swivel pilot valve 48b outputs a swivel pilot pressure of a magnitude corresponding to the magnitude of the swivel operation, which is a pilot pressure corresponding to the direction of the swivel operation.

The plurality of control valves enable control of the operation of the hydraulic actuator corresponding to the operating device by opening the valve with an opening area corresponding to the operation given to each of the plurality of operating devices, and the boom. The control valve 52, the arm control valve 54, the bucket control valve 56, and the swivel control valve 58 are included.

The boom control valve 52 is interposed between the first pump 31 and the boom cylinder 22, and is opened by the boom pilot pressure input from the boom pilot valve 42b of the boom operating device 42. As a result, control of the supply of hydraulic oil from the first pump 31 to the boom cylinder 22 is executed.

Specifically, the boom control valve 52 according to this embodiment is composed of a three-position pilot switching valve having a pair of pilot ports. When the boom control valve 52 does not receive the pilot pressure input from the boom operating device 42, the boom control valve 52 holds a neutral position to shut off the first pump 31 and the boom cylinder 22, and the boom raising pilot line from the boom operating device 42. When the boom raising pilot pressure is input through 43A, an oil passage is formed to guide the hydraulic oil discharged by the first pump 31 to the head side chamber 22a of the boom cylinder 22 at a flow rate corresponding to the magnitude of the boom raising pilot pressure. Then, when the boom cylinder 22 is extended and the boom lowering pilot pressure is input from the boom operating device 42 through the boom lowering pilot line 43B, the hydraulic oil discharged by the first pump 31 is of the boom lowering pilot pressure. An oil passage leading to the rod side chamber 22b of the boom cylinder 22 is formed at a flow rate corresponding to the size, and the boom cylinder 22 is contracted. Therefore, the boom operating device 42 including the boom operating lever 42a has a function of opening the boom control valve 52 in response to the boom operation given to the boom operating lever 42a.

The arm control valve 54 is interposed between the second pump 32 and the arm cylinder 24, and is opened by the arm pilot pressure input from the arm pilot valve 44b of the arm operating device 44. As a result, control of the supply of hydraulic oil from the second pump 32 to the arm cylinder 24 is executed.

Specifically, the arm control valve 54 according to this embodiment is composed of a three-position pilot switching valve having a pair of pilot ports. When the arm control valve 54 does not receive the input of the pilot pressure from the arm operating device 44, the arm control valve 54 holds a neutral position to shut off the second pump 32 and the arm cylinder 24, and the arm pulling pilot from the arm operating device 44. When the arm pulling pilot pressure is input through the line 45A, an oil passage is formed to guide the hydraulic oil discharged by the second pump 32 to the head side chamber 24a of the arm cylinder 24 at a flow rate corresponding to the magnitude of the arm pulling pilot pressure. Then, when the arm cylinder 24 is extended and the arm pushing pilot pressure is input from the arm operating device 44 through the arm pushing pilot line 45B, the hydraulic oil discharged by the second pump 32 is the magnitude of the arm pushing pilot pressure. An oil passage leading to the rod side chamber 24b of the arm cylinder 24 is formed at a flow rate corresponding to the above, and the arm cylinder 24 is contracted. Therefore, the arm operating device 44 including the arm operating lever 44a has a function of opening the arm control valve 54 in response to the arm operation given to the arm operating lever 44a.

The bucket control valve 56 is interposed between the third pump 33 and the bucket cylinder 26, and is opened by the bucket pilot pressure input from the bucket pilot valve 46b of the bucket operating device 46. As a result, control of the supply of hydraulic oil from the third pump 33 to the bucket cylinder 26 is executed.

The bucket control valve 56 is interposed between the third pump 33 and the bucket cylinder 26, and is operated by the pilot pressure input from the bucket operating device 46 to open the valve from the third pump 33. It controls the supply of hydraulic oil to the bucket cylinder 26. Specifically, the bucket control valve 56 according to this embodiment is composed of a three-position pilot switching valve having a pair of pilot ports. When the bucket control valve 56 does not receive the input of the pilot pressure from the bucket operating device 46, the bucket control valve 56 holds a neutral position to shut off the third pump 33 and the bucket cylinder 26, and the bucket excavation pilot from the bucket operating device 46. When the bucket drilling pilot pressure is input through the line 47A, an oil passage is formed to guide the hydraulic oil discharged by the third pump 33 to the head side chamber 26a of the bucket cylinder 26 at a flow rate corresponding to the magnitude of the bucket drilling pilot pressure. Then, when the bucket cylinder 26 is extended and the bucket opening pilot pressure is input from the bucket operating device 46 through the bucket opening pilot line 47B, the hydraulic oil discharged by the third pump 33 is the magnitude of the bucket opening pilot pressure. An oil passage leading to the rod side chamber 26b of the bucket cylinder 26 is formed at a flow rate corresponding to the current, and the bucket cylinder 26 is contracted. Therefore, the bucket operating device 46 including the bucket operating lever 46a has a function of opening the bucket control valve 56 in response to the bucket operation given to the bucket operating lever 46a.

The swivel control valve 58 is interposed between the third pump 33 and the swivel motor 28, and receives the input of the pilot pressure output by the swivel operation device 48 to open the valve, thereby opening the third pump. The supply of hydraulic oil from 33 to the swivel motor 28 is controlled. The swivel control valve 58 can be configured by a pilot hydraulic control valve at three positions, like the boom control valve 52 and the like, for example.

Each of the plurality of speed-increasing valves is a valve that is opened and closed in order to accelerate the movement of the plurality of hydraulic actuators by merging or regenerating hydraulic oil and controlling the speed-up. The plurality of speed-increasing valves include a boom merging valve 53, a first arm merging valve 51, a second arm merging valve 55, a bucket merging valve 57, and an arm regenerating valve 59.

The boom merging valve 53 is provided in the middle of the boom merging oil passage. The boom merging oil passage is formed by merging a part of the hydraulic oil discharged by the second pump 32 with the hydraulic oil supplied from the first pump 31 to the head side chamber 22a of the boom cylinder 22. It is an oil passage for accelerating the extension of the boom cylinder 22 and the boom raising operation accompanying the extension, and is the second pump oil passage in the middle of the second pump oil passage from the second pump 32 to the arm control valve 54. It branches from the head side chamber 22a and is connected to the head side chamber 22a. The boom merging valve 53 is provided in the middle of the boom merging oil passage, so that the boom merging valve 53 is interposed between the second pump 32 and the head side chamber 22a. The boom merging valve 53 is composed of, for example, a pilot-operated switching valve, and opens with an opening area corresponding to the magnitude of the boom merging pilot pressure only when the boom merging pilot pressure, which is a valve opening command, is input. As a result, a part of the hydraulic oil discharged from the second pump 32 reaches the opening area of the hydraulic oil supplied from the first pump 31 to the head side chamber 22a of the boom cylinder 22 through the boom control valve 52. Allows merging at the corresponding flow rates.

The first arm merging valve 51 is provided in the middle of the first arm merging oil passage. The first arm merging oil passage is formed by merging a part of the hydraulic oil discharged by the first pump 31 with the hydraulic oil supplied from the second pump 32 to the rod side chamber 24b of the arm cylinder 24. It is an oil passage for accelerating the contraction of the arm cylinder 24 and the arm pushing operation accompanying the contraction, and is the first pump oil passage in the middle of the first pump oil passage from the first pump 31 to the boom control valve 52. It branches from and is connected to the rod side chamber 24b. The first arm merging valve 51 is provided in the middle of the first arm merging oil passage, so that the first arm merging valve 51 is interposed between the first pump 31 and the rod side chamber 24b. The first arm merging valve 51 is composed of, for example, a pilot-operated switching valve, and corresponds to the magnitude of the first arm merging pilot pressure only when the input of the first arm merging pilot pressure, which is a valve opening command, is received. The valve is opened in the opening area, whereby a part of the hydraulic oil discharged from the first pump 31 is supplied from the second pump 32 to the rod side chamber 24b of the arm cylinder 24 through the arm control valve 54. It is allowed to join the oil at a flow rate corresponding to the opening area.

The second arm merging valve 55 is provided in the middle of the second arm merging oil passage. The second arm merging oil passage joins a part of the hydraulic oil discharged by the third pump 33 with the hydraulic oil supplied from the second hydraulic pump 32 to the rod side chamber 24b of the arm cylinder 24. It is an oil passage for accelerating the contraction of the arm cylinder 24 and the arm pushing operation accompanying the contraction, and the third pump oil is in the middle of the third pump oil passage from the third pump 33 to the bucket control valve 56. It branches off from the road and is connected to the rod side chamber 24b. The second arm merging valve 55 is provided in the middle of the second arm merging oil passage, so that the second arm merging valve 55 is interposed between the third pump 33 and the rod side chamber 24b. The second arm merging valve 55 is composed of, for example, a pilot-operated switching valve, and corresponds to the magnitude of the second arm merging pilot pressure only when the input of the second arm merging pilot pressure, which is a valve opening command, is received. The valve is opened in the opening area, whereby a part of the hydraulic oil discharged from the third pump 33 is supplied from the second pump 32 to the rod side chamber 24b of the arm cylinder 24 through the arm control valve 54. It is allowed to join the oil at a flow rate corresponding to the opening area.

The bucket merging valve 57 is provided in the middle of the bucket merging oil passage. The bucket merging oil passage joins a part of the hydraulic oil discharged by the first pump 31 with the hydraulic oil supplied from the third pump 33 to the head side chamber 26a and the rod side chamber 26b of the bucket cylinder 26. It is an oil passage for accelerating the expansion and contraction of the bucket cylinder 26 and the bucket rotation operation accompanying the expansion and contraction of the bucket cylinder 26, and is in the middle of the first pump oil passage from the first pump 31 to the boom control valve 52. It branches from the first pump oil passage and is connected to the head side chamber 26a and the rod side chamber 26b. The bucket merging valve 57 is provided in the middle of the bucket merging oil passage, and is interposed between the first pump 31 and the head side chamber 26a and the rod side chamber 26b. The bucket merging valve 57 is composed of, for example, a three-position pilot-operated switching valve having a pair of pilot ports, and a bucket merging pilot pressure (bucket drilling merging pilot pressure or bucket) that is a valve opening command to any of the pair of pilot ports. Only when the input of the opening merging pilot pressure) is received, the valve is opened in the direction corresponding to the pilot port and the opening area corresponding to the magnitude of the bucket merging pilot pressure, whereby the valve is discharged from the first pump 31. A part of the hydraulic oil is merged with the hydraulic oil supplied from the third pump 33 to the head side chamber 26a or the rod side chamber 26b of the bucket cylinder 26 through the bucket control valve 56 at a flow rate corresponding to the opening area. Tolerate.

The arm regeneration valve 59 is provided in the middle of the arm regeneration oil passage. In the arm regeneration oil passage, at least a part of the hydraulic oil discharged from the rod side chamber 24b of the arm cylinder 24 when the arm cylinder 24 is extended, that is, when the arm is pulled, is recombined into the head side chamber 24a of the arm cylinder 24. It is an oil passage for supplying and accelerating the arm pulling operation, bypassing the arm control valve 54, and connecting the head side chamber 24a and the rod side chamber 24b of the arm cylinder 24. The arm regeneration valve 59 is provided in the middle of the arm regeneration oil passage so as to be interposed between the head side chamber 24a and the rod side chamber 24b. The arm regeneration valve is composed of, for example, an electromagnetically operated flow rate adjusting valve, and opens with an opening area corresponding to the magnitude of the arm regeneration command signal only when an arm regeneration command signal, which is a valve opening command, is input. This allows the hydraulic oil discharged from the rod side chamber 24b to be resupplied to the head side chamber 24a.

In this embodiment, since the arm pulling operation can be accelerated by opening the arm regeneration valve 59, the increase is due to the merging of hydraulic oil through the first arm merging valve 51 and the second arm merging valve 55. The speed is performed only for the arm pushing operation. That is, the merging through the first and second arm merging valves 51 and 57 is performed only on the hydraulic oil supplied to the rod side chamber 24b of the arm cylinder 24. When the arm regeneration valve 59 is omitted, the merging may be performed on both the head side chamber 24a and the rod side chamber 24b of the arm cylinder 24.

The hydraulic excavator according to this embodiment further includes a plurality of speed increasing control devices. The speed-up control device controls the speed-up of each hydraulic actuator by opening and closing each of the plurality of speed-up valves. The plurality of speed-up control devices include a boom merging control device, an arm merging control device, a bucket merging control device, and an arm regeneration control device. Specifically, the hydraulic excavator includes a plurality of pilot pressure sensors, a plurality of merging operation valves, and a controller 80 as elements for constituting the plurality of speed-increasing control devices.

The plurality of pressure sensors generate a pilot pressure detection signal having a magnitude corresponding to the pilot pressure output from the plurality of operating devices 42, 44, 46 and input it to the controller 80. It includes boom pilot pressure sensors 63A and 63B, arm pilot pressure sensors 65A and 65B, and bucket pilot pressure sensors 67A and 67B as shown in FIG. The boom pilot pressure sensors 63A and 63B are supplied to the boom control valve 52 from the boom operating device 42 through the boom raising pilot line 43A and the boom lowering pilot line 43B, respectively, and the boom raising pilot pressure and the boom. A detection signal corresponding to each lower pilot pressure is generated. Similarly, the arm pulling pilot pressure sensors 65A and 65B are supplied to the arm pulling pilot pressure 54 from the arm operating device 44 through the arm pulling pilot line 45A and the arm pushing pilot line 45B, respectively. And the detection signals corresponding to the arm pushing pilot pressure are generated, and the bucket pilot pressure sensors 67A and 67B pass through the bucket excavation pilot line 47A and the bucket opening pilot line 47B from the bucket operating device 46, respectively. A detection signal corresponding to the bucket excavation pilot pressure and the bucket opening pilot pressure supplied to the bucket control valve 56 is generated.

The plurality of merging operation valves are interposed between the pilot hydraulic source (not shown) and the plurality of merging valves, respectively, and the plurality of merging valves are opened by receiving an input of a merging command from the controller 80. The pilot pressure (merging pilot pressure) input to each and the corresponding opening area of the merging valve are changed, thereby enabling merging control. Specifically, the plurality of merging operation valves include a boom merging operation valve 73, a first arm merging operation valve 71, a second arm merging operation valve 75, and a bucket merging operation valve 77. Each of the plurality of merging operation valves can be configured by, for example, an electromagnetic proportional pressure reducing valve.

The boom merging operation valve 73 is interposed between the pilot hydraulic source and the boom merging valve 53. The boom merging operation valve 73 opens when it receives an input of a boom merging command signal from the controller 80, and generates a secondary pressure corresponding to the magnitude of the boom merging command signal. The secondary pressure is input to the pilot port of the boom merging valve 53 as the boom merging pilot pressure.

The first arm merging operation valve 71 is interposed between the pilot hydraulic source and the pilot port of the first arm merging valve 51, and opens when the first arm merging command signal is input from the controller 80. A secondary pressure corresponding to the magnitude of the first arm merging command signal is generated by valve. The secondary pressure is input to the pilot port of the first arm merging valve 51 as the first arm merging pilot pressure.

The second arm merging operation valve 75 is interposed between the pilot hydraulic source and the pilot port of the second arm merging valve 55, and opens when a second arm merging command signal is input from the controller 80. A secondary pressure corresponding to the magnitude of the second arm merging command signal is generated by valve. The secondary pressure is input to the pilot port of the second arm merging valve 55 as the second arm merging pilot pressure.

The bucket merging operation valve 77 is interposed between the pilot hydraulic source and the pilot port of the bucket merging valve 57, and opens when a bucket merging command signal is input from the controller 80 to join the bucket. Generates a secondary pressure corresponding to the magnitude of the command signal. The secondary pressure is input as the bucket pilot pressure to any of the pair of pilot ports of the bucket merging valve 57.

The controller 80 is composed of, for example, a microcomputer, and by inputting command signals to the plurality of operating valves 71, 73, 75, 77 and the arm regeneration valve 59, these valves are opened with an appropriate opening area. Therefore, speed-up control (merging control and regeneration control) is executed. Specifically, the controller 80 includes a boom merging control unit 83, a first arm merging control unit 81, a second arm merging control unit 85, a bucket merging control unit 87, and an arm regeneration control unit 89 as shown in FIG. ..

The boom merging control unit 83 constitutes a boom merging control device together with the boom pilot pressure sensors 63A and 63B and the boom merging operation valve 73. The boom merging control device opens the boom merging valve 53 by applying a boom merging pilot pressure, which is a valve opening command, to the boom merging valve 53 in response to a boom operation given to the boom operating lever 42a of the boom operating device 42. Let me speak. Specifically, in the boom merging control unit 83, the boom pilot pressure input from the boom pilot pressure sensors 63A and 63B (in this embodiment, the boom raising pilot pressure input from the boom pilot pressure sensor 63A) is equal to or higher than a certain level. In the case of, the boom merging command signal corresponding to the magnitude of the boom raising pilot pressure is generated, and the boom merging command signal is input to the boom merging operation valve 73.

The first arm merging control unit 81 constitutes the first arm merging control device together with the arm pilot pressure sensors 65A and 65B and the first arm merging operation valve 71. The first arm merging control device applies a first arm merging pilot pressure, which is a valve opening command, to the first arm merging valve 51 in response to an arm operation given to the arm operating lever 44a of the arm operating device 44. The first arm merging valve 51 is opened. Specifically, the first arm merging control unit 81 has an arm pilot pressure input from the arm pilot pressure sensors 65A and 65B, and in this embodiment, an arm push pilot pressure input from the arm pilot pressure sensor 65B. Is above a certain level, the first arm merging command signal corresponding to the magnitude of the arm pushing pilot pressure is generated, and the first arm merging command signal is input to the first arm merging operation valve 71.

The second arm merging control unit 85 constitutes a second arm merging control device together with the arm pilot pressure sensors 65A and 65B and the second arm merging operation valve 75. The second arm merging control device applies a second arm merging pilot pressure, which is a valve opening command, to the second arm merging valve 55 in response to the arm operation to open the second arm merging valve 55. Specifically, the second arm merging control unit 85 corresponds to the magnitude of the arm pushing pilot pressure when the arm pilot pressure (in this embodiment, the arm pushing pilot pressure) is equal to or higher than a certain level. An arm merging command signal is generated, and the second arm merging command signal is input to the second arm merging operation valve 75.

The bucket merging control unit 87 constitutes a bucket merging control device together with the bucket pilot pressure sensors 67A and 67B and the bucket merging operation valve 77. The bucket merging control device opens the bucket merging valve 57 by applying a bucket merging pilot pressure, which is a valve opening command, to the bucket merging valve 57 in response to a bucket operation given to the bucket operating lever 46a of the bucket operating device 46. Let me speak. Specifically, the bucket merging control unit 87 generates a bucket merging command signal corresponding to the magnitude of the bucket pilot pressure when the bucket pilot pressure input from the bucket pilot pressure sensors 67A and 67B is equal to or higher than a certain level. , The bucket merging command signal is input to the bucket merging operation valve 77.

When the arm pulling pilot pressure detected by the arm pilot pressure sensor 65A is equal to or higher than a certain level, the arm regeneration control unit 89 generates an arm regeneration command signal corresponding to the magnitude of the arm pulling pilot pressure to regenerate the arm. Input to the valve 59, thereby controlling the regeneration flow rate through the arm regeneration valve 59.

Further, this hydraulic excavator is provided with an excavation motion detection unit as a first feature. The excavation motion detection unit detects the presence or absence of the excavation motion by the bucket 16 accompanied by the rotation of the arm 14 in the pulling direction, that is, the arm pulling motion.

The excavation motion detection unit according to this embodiment includes an arm cylinder head pressure sensor 64 shown in FIGS. 2 and 3 and an excavation operation determination unit 84 included in the controller 80. The arm cylinder head pressure sensor 64 generates a detection signal for the head pressure of the arm cylinder 24, that is, the pressure of the hydraulic oil in the head side chamber 24a of the arm cylinder 24, and causes the controller 80 to generate a detection signal. input. The excavation operation determination unit 84 determines that the excavation operation is performed when the head pressure detected by the arm cylinder head pressure sensor 64 is equal to or higher than a certain level, and in other cases, the excavation operation determination unit 84 determines that the excavation operation is performed. It is determined that the excavation operation is not performed.

The second feature of the hydraulic excavator is that, among the plurality of merging control units, the merging control unit involved in controlling the merging of hydraulic oil discharged from the first pump 31, that is, the bucket merging control unit 87 and the first The 1-arm merging control unit 81 has a function of changing the content of the bucket merging control according to the determination result by the excavation operation determination unit 84. The specific contents will be described with reference to FIGS. 4 to 7.

FIG. 4 is a flowchart showing a bucket merging control operation performed by the controller 80. The controller 80 captures various signals (step S10). The excavation operation determination unit 84 of the controller 80 determines whether or not the excavation operation is currently being performed based on the head pressure detection signal input from the arm cylinder head pressure sensor 64 (step S12). ..

When the excavation operation determination unit 84 determines that the excavation operation has not been performed (NO in step S12), the bucket merging control unit 87 of the controller 80 determines whether or not the magnitude of the bucket pilot pressure is equal to or greater than a certain level. Is determined (step S14). The bucket merging control unit 87 generates a bucket merging command signal corresponding to the size of the bucket merging control unit 87 only when the bucket pilot pressure is equal to or higher than a certain level (YES in step S14), and inputs the bucket merging command signal to the bucket merging operation valve 77 (step). S16). When the bucket pilot pressure is less than a certain value, the bucket merging control unit 87 does not input the bucket merging command signal (step S18).

When the bucket merging operation valve 77 receives the input of the bucket merging command signal, the bucket merging operation valve 77 opens at an opening degree corresponding to the magnitude of the bucket merging command signal to generate a secondary pressure corresponding to the opening degree. .. The secondary pressure is input to the bucket merging valve 57 as a bucket merging pilot pressure. The bucket merging valve 57 opens at an opening degree corresponding to the bucket merging pilot pressure, whereby merging at a flow rate corresponding to the magnitude of the bucket merging pilot pressure, that is, from the third pump 33 to the bucket cylinder. It allows the hydraulic oil discharged from the first pump 31 to merge with the hydraulic oil supplied to the 26. This means that the bucket operation other than the excavation operation is accelerated in consideration of the bucket operation given to the bucket operation lever 46a by the operator, for example, the bucket opening operation is accelerated and the operation in the bucket excavation direction other than the excavation work is accelerated. , Is possible.

The characteristics of the bucket merging pilot pressure (secondary pressure of the bucket merging operation valve 77) with respect to the bucket operation can be appropriately set. FIG. 5 shows an example of the characteristic with a broken line. The characteristic of the bucket merging pilot pressure shown here is a characteristic that increases as the bucket operation amount increases in a region where the bucket operation amount exceeds a certain level. Further, the characteristic is a characteristic corresponding to the bucket pilot pressure input from the bucket operating device 46 to the bucket control valve 56 in response to the bucket operation (characteristic of rising later than the bucket pilot pressure). ..

On the other hand, when the excavation operation determination unit 84 determines that the excavation operation is being performed (YES in step S12), the bucket merge control unit 87 of the controller 80 receives the bucket merge command signal regardless of the magnitude of the bucket pilot pressure. And the input to the bucket merging operation valve 77 are stopped (step S18), thereby prohibiting the rise of the bucket merging pilot pressure due to the opening of the bucket merging operation valve 77, as shown in FIG. .. That is, the bucket merging valve 57 is kept in the closed state, and the merging of the hydraulic oil from the first pump 31 to the hydraulic oil supplied from the third pump 33 to the bucket cylinder 26 through the bucket merging valve 57 is prohibited.

The prohibition of bucket merging from the first pump 31 during the excavation operation makes it possible to effectively reduce the energy loss in the excavation operation. When the excavation operation is being performed, the drive load of the bucket cylinder 26 for moving the bucket 16 increases due to the bucket 16 receiving the excavation reaction force from the ground, and the hydraulic oil supplied to the bucket cylinder 26 While the pressure increases, the drive load of the boom cylinder 22 connected to the first pump 31 decreases by the amount that the excavation reaction force acts as an upward force on the boom 12, and the head side chamber 22a of the boom cylinder 22 decreases. The pressure of the hydraulic oil supplied to the cylinder becomes low. Therefore, if the bucket merging valve 57 is opened and the first pump 31 is communicated with the bucket cylinder 26, the discharge pressure of the first pump 31 becomes high and the front-rear differential pressure of the boom control valve 52 becomes large. As a result, energy loss increases. Therefore, prohibition of merging of hydraulic oil through the bucket merging valve 57 during such excavation operation, that is, shutting off the bucket cylinder 26 from the first pump 31 prevents a significant increase in the discharge pressure of the first pump 31. It is possible to suppress the increase in the energy loss caused by the above. Moreover, since the bucket 16 is not required to move very quickly in the excavation operation, even if the speed increase of the movement of the bucket 16 due to the opening of the bucket merging valve 57 is prohibited, the influence on the work efficiency is small.

FIG. 7 is a flowchart showing a first arm merging control operation (control operation for merging hydraulic oil from the first pump 31 to the arm drive circuit) performed by the controller 80. Similar to the bucket merging control, the controller 80 takes in various signals (step S10) and determines whether or not there is an excavation operation (step S12).

When the excavation operation determination unit 84 determines that the excavation operation has not been performed (NO in step S12), the first arm merging control unit 81 of the controller 80 has an arm pilot pressure (arm push pilot pressure in this embodiment). It is determined whether or not the size of is equal to or larger than a certain value (step S24). The first arm merging control unit 81 generates a first arm merging command signal corresponding to the magnitude only when the arm pushing pilot pressure is equal to or higher than a certain level (YES in step S24), and the first arm merging operation is performed. Input to the valve 71 (step S26). The first arm merging control unit 81 does not input the arm merging command signal when the arm pushing pilot pressure is less than a certain level (step S28).

The first arm merging operation valve 71 opens at an opening corresponding to the magnitude of the first arm merging command signal, and its secondary pressure is used as the first arm merging pilot pressure on the first arm merging valve 51. Entered. The first arm merging valve 51 opens at an opening degree corresponding to the first arm pilot pressure, whereby merging at a flow rate corresponding to the magnitude of the first arm pilot pressure, that is, the second pump. Allowing the merging of the hydraulic oil discharged from the first pump 31 into the hydraulic oil supplied from the 32 to the rod side chamber 24b of the arm cylinder 24, the speed of the arm pushing operation can be increased. The characteristics of the first arm merging pilot pressure (secondary pressure of the first arm merging operation valve 71) here can be appropriately set in the same manner as the characteristics of the bucket merging pilot pressure.

On the other hand, when the excavation operation determination unit 84 determines that the excavation operation is being performed (YES in step S12), the first arm merging control unit 81 is the first arm regardless of the magnitude of the arm pushing pilot pressure. The generation of the merging command signal and the input to the first arm merging operation valve 71 are stopped (step S28), whereby the first arm merging valve 51 is kept in the closed state and passed through the first arm merging valve 51. Prohibits the merging of hydraulic oil. This, in combination with the prohibition of hydraulic oil merging (bucket merging) through the bucket merging valve 57, enables effective reduction of energy loss due to the front-rear differential pressure of the boom control valve 52 in the excavation operation. ..

The present invention is not limited to the embodiments described above. The present invention includes, for example, the following aspects.

(A) Target of merging The present invention can be widely applied to at least a hydraulic excavator in which hydraulic oil is merged from a first pump for driving a boom to a bucket hydraulic actuator. Therefore, the boom merging, the first arm merging (merging from the first pump 31 to the arm cylinder 24) and the second arm merging (merging from the third pump 33 to the arm cylinder 24) according to the embodiment are omitted as appropriate. It is possible to be done. Further, the bucket merging may be performed only in a specific direction (for example, only in the bucket excavation direction) such as the boom merging and the arm merging according to the above embodiment. On the contrary, the boom merging and the arm merging may be performed in both directions as in the bucket merging according to the embodiment.

However, when the first arm merging (merging from the first pump) is adopted in addition to the bucket merging, the first arm merging is prohibited at the time of excavation operation detection as in the case of the bucket merging. preferable. This ensures the independence of the boom drive circuit between the first pump and the boom hydraulic actuator during the excavation operation and the effect of prohibiting bucket merging, that is, the reduction of energy loss in the boom control valve during the excavation operation. It makes it possible to obtain the effect more reliably.

(B) Judgment of presence / absence of excavation operation The determination of presence / absence of excavation operation is not limited to the one based on the head pressure of the boom cylinder as in the embodiment. The determination may be made based on, for example, the discharge pressure of the second pump in charge of the main drive of the arm cylinder. Alternatively, based on the head pressure measurement value Pha, rod pressure measurement value Pra, head side cross-sectional area Aha and rod side cross-sectional area Ara for the arm cylinder, the thrust Fam of the arm cylinder is used using the following equation (1). May be calculated and it may be determined that the excavation operation is performed when the thrust Fam is equal to or higher than a certain level.

Fam = Pha x Aha-Pra x Ara ... (1)
(C) Cooperation between each operation and the control valve In the present invention, the boom operation, the arm operation and the bucket operation given to each of the boom operation member, the arm operation member and the bucket operation member, and the boom control valve, the arm control valve and The specific mode of cooperation with the valve opening operation of the bucket control valve is not limited. Each of the plurality of operating devices (boom operating device 42, arm operating device 44, and bucket operating device 46) according to the embodiment is described by inputting a pilot pressure corresponding to an operation given to the operating member to the control valve. The operation and the valve opening operation of the control valve are linked, and the operation device is an electromagnetic operation valve interposed between the pilot hydraulic source and the pilot port of each control valve, and an operation given to the operation member. An electric lever device that generates an operation command signal, which is an electric signal corresponding to the above, and a pilot command signal corresponding to the generated operation command signal are generated and input to the electromagnetic operation valve to obtain the operation command signal. It may include a pilot command circuit for inputting the corresponding pilot pressure to the control valve.

7 Lower running body (base machine)
8 Upper swivel body (base machine)
10 Work attachment 12 Boom 14 Arm 16 Bucket 22 Boom cylinder (boom hydraulic actuator)
24 Arm cylinder (arm hydraulic actuator)
26 Bucket cylinder (bucket hydraulic actuator)
31 1st pump 32 2nd pump 33 3rd pump 42 Boom operating device 42a Boom operating lever (boom operating member)
44 Arm operating device 44a Arm operating lever (arm operating member)
46 Bucket operating device 46a Bucket operating lever (bucket operating member)
51 1st arm merging valve 52 Boom control valve 54 Arm control valve 56 Bucket control valve 57 Bucket merging valve 64 Arm cylinder head pressure sensor (composed of excavation motion detection unit)
65A, 65B Arm pilot pressure sensor (consists of arm merging control device)
67A, 67B Bucket pilot pressure sensor (consists of bucket merging control device)
71 1st arm merging operation valve (consists of arm merging control device)
77 Bucket merging operation valve (consists of bucket merging control device)
80 Controller 81 1st arm merging control unit (configures arm merging control device)
84 Excavation motion determination unit (composed of excavation motion detection unit)
87 Bucket merging control unit (configures bucket merging control device)

Claims (4)

It ’s a hydraulic excavator,
With a runnable base machine
With a boom that can be mounted up and down
An arm that is rotatably connected to the tip of this boom,
A bucket that is rotatably connected to the tip of this arm,
A boom hydraulic actuator that operates to raise and lower the boom by receiving the supply of hydraulic oil,
An arm hydraulic actuator that operates to rotate the arm with respect to the boom by receiving the supply of hydraulic oil, and
A bucket hydraulic actuator that operates to rotate the bucket with respect to the arm by receiving the supply of hydraulic oil, and
A first pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the boom hydraulic actuator and the bucket hydraulic actuator.
A second pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the arm hydraulic actuator,
A third pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the bucket hydraulic actuator,
A boom operating member that receives a boom operation to move the boom hydraulic actuator,
An arm operating member that receives an arm operation to move the arm hydraulic actuator, and
A bucket operating member that receives a bucket operation to move the bucket hydraulic actuator,
A boom control valve that is interposed between the first pump and the boom hydraulic actuator and controls the supply of hydraulic oil from the first pump to the boom hydraulic actuator by opening the valve in response to the boom operation.
An arm control valve that is interposed between the second pump and the arm hydraulic actuator and controls the supply of hydraulic oil from the second pump to the arm hydraulic actuator by opening the valve in response to the arm operation.
A bucket control valve that is interposed between the third pump and the bucket hydraulic actuator and controls the supply of hydraulic oil from the third pump to the bucket hydraulic actuator by opening the valve in response to the bucket operation.
The hydraulic oil that is interposed between the first pump and the bucket hydraulic actuator, opens the valve only when a valve opening command is received, and is discharged by the first pump is supplied from the third pump to the bucket hydraulic actuator. A bucket merging valve that allows merging with the hydraulic fluid to be made,
An excavation operation detection unit that detects the presence or absence of excavation operation by the bucket accompanied by rotation of the arm in the pulling direction, and hydraulic oil supplied to the arm hydraulic actuator to rotate the arm in the pulling direction. Excavation motion detection unit that determines that the excavation motion is being performed when the pressure of
Wherein when said excavating operation detecting unit and drilling operation is not performed is determined is by opening the bucket confluence valve gives the opening command to said bucket confluence valve in response to said bucket operation, the drilling operation When the excavation operation detection unit determines that the excavation operation is being performed, the bucket merging control device prohibits the merging through the bucket merging valve without giving the valve opening command to the bucket merging valve regardless of the bucket operation. , Equipped with a hydraulic excavator. It ’s a hydraulic excavator,
With a runnable base machine
With a boom that can be mounted up and down
An arm that is rotatably connected to the tip of this boom,
A bucket that is rotatably connected to the tip of this arm,
A boom hydraulic actuator that operates to raise and lower the boom by receiving the supply of hydraulic oil,
An arm hydraulic actuator that operates to rotate the arm with respect to the boom by receiving the supply of hydraulic oil, and
A bucket hydraulic actuator that operates to rotate the bucket with respect to the arm by receiving the supply of hydraulic oil, and
A first pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the boom hydraulic actuator and the bucket hydraulic actuator.
A second pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the arm hydraulic actuator,
A third pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the bucket hydraulic actuator,
A boom operating member that receives a boom operation to move the boom hydraulic actuator,
An arm operating member that receives an arm operation to move the arm hydraulic actuator, and
A bucket operating member that receives a bucket operation to move the bucket hydraulic actuator,
A boom control valve that is interposed between the first pump and the boom hydraulic actuator and controls the supply of hydraulic oil from the first pump to the boom hydraulic actuator by opening the valve in response to the boom operation.
An arm control valve that is interposed between the second pump and the arm hydraulic actuator and controls the supply of hydraulic oil from the second pump to the arm hydraulic actuator by opening the valve in response to the arm operation.
A bucket control valve that is interposed between the third pump and the bucket hydraulic actuator and controls the supply of hydraulic oil from the third pump to the bucket hydraulic actuator by opening the valve in response to the bucket operation.
The hydraulic oil that is interposed between the first pump and the bucket hydraulic actuator, opens the valve only when a valve opening command is received, and is discharged by the first pump is supplied from the third pump to the bucket hydraulic actuator. A bucket merging valve that allows merging with the hydraulic fluid to be made,
An excavation operation detection unit that detects the presence or absence of an excavation operation by the bucket accompanied by rotation of the arm in the pulling direction, and determines whether or not the excavation operation is performed based on the discharge pressure of the second pump. Excavation motion detection unit and
When the excavation operation detection unit determines that the excavation operation has not been performed, the bucket confluence valve is given the valve opening command in response to the bucket operation to open the bucket confluence valve, and the excavation operation is performed. When the excavation operation detection unit determines that the excavation operation is being performed, the bucket merging control device prohibits the merging through the bucket merging valve without giving the valve opening command to the bucket merging valve regardless of the bucket operation. , Equipped with a hydraulic excavator. It ’s a hydraulic excavator,
With a runnable base machine
With a boom that can be mounted up and down
An arm that is rotatably connected to the tip of this boom,
A bucket that is rotatably connected to the tip of this arm,
A boom hydraulic actuator that operates to raise and lower the boom by receiving the supply of hydraulic oil,
An arm hydraulic actuator that operates to rotate the arm with respect to the boom by receiving the supply of hydraulic oil, and
A bucket hydraulic actuator that operates to rotate the bucket with respect to the arm by receiving the supply of hydraulic oil, and
A first pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the boom hydraulic actuator and the bucket hydraulic actuator.
A second pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the arm hydraulic actuator,
A third pump that is a hydraulic pump that discharges hydraulic oil and can be connected to the bucket hydraulic actuator,
A boom operating member that receives a boom operation to move the boom hydraulic actuator,
An arm operating member that receives an arm operation to move the arm hydraulic actuator, and
A bucket operating member that receives a bucket operation to move the bucket hydraulic actuator,
A boom control valve that is interposed between the first pump and the boom hydraulic actuator and controls the supply of hydraulic oil from the first pump to the boom hydraulic actuator by opening the valve in response to the boom operation.
An arm control valve that is interposed between the second pump and the arm hydraulic actuator and controls the supply of hydraulic oil from the second pump to the arm hydraulic actuator by opening the valve in response to the arm operation.
A bucket control valve that is interposed between the third pump and the bucket hydraulic actuator and controls the supply of hydraulic oil from the third pump to the bucket hydraulic actuator by opening the valve in response to the bucket operation.
The hydraulic oil that is interposed between the first pump and the bucket hydraulic actuator, opens the valve only when a valve opening command is received, and is discharged by the first pump is supplied from the third pump to the bucket hydraulic actuator. A bucket merging valve that allows merging with the hydraulic fluid to be made,
An excavation operation detection unit that detects the presence or absence of an excavation operation by the bucket accompanied by rotation of the arm in the pulling direction, and determines that the excavation operation is performed when the thrust of the arm hydraulic actuator is equal to or higher than a certain level. Excavation motion detector and
When the excavation operation detection unit determines that the excavation operation has not been performed, the bucket confluence valve is given the valve opening command in response to the bucket operation to open the bucket confluence valve, and the excavation operation is performed. When the excavation operation detection unit determines that the excavation operation is being performed, the bucket merging control device prohibits the merging through the bucket merging valve without giving the valve opening command to the bucket merging valve regardless of the bucket operation. , Equipped with a hydraulic excavator. The first pump according to any one of claims 1 to 3, which is interposed between the first pump and the arm hydraulic actuator and opens only when a valve opening command is received. An arm merging valve that allows the hydraulic oil discharged by the engine to merge with the hydraulic oil supplied from the second pump to the arm hydraulic actuator, and when the excavation operation is not detected by the excavation operation detection unit, the above A valve opening command is given to the arm merging valve in response to the arm operation to open the arm merging valve, and when the excavation operation is detected by the excavation operation detection unit, the arm merging regardless of the arm operation. A hydraulic excavator further comprising an arm merging control device that prohibits the merging through the arm merging valve without giving the valve opening command to the valve.

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