JP6915436B2 - Swivel type hydraulic work machine - Google Patents

Description

The present invention relates to a swivel type hydraulic work machine such as a hydraulic excavator.

The swivel hydraulic work machine generally includes a lower traveling body, an upper swivel body rotatably mounted on the lower traveling body, a work device mounted on the upper swivel body, and a hydraulic motor that swivels the upper swivel body. A swivel motor, a hydraulic pump for discharging hydraulic oil to be supplied to the swivel motor, and a swivel control valve interposed between the hydraulic pump and the swivel motor are provided. The swivel control valve opens and closes according to the operation of the swivel lever by the operator, and changes the flow rate of the hydraulic oil supplied to the swivel motor among the hydraulic oils discharged from the hydraulic pump.

The hydraulic oil discharged by the hydraulic pump is often used not only for the swivel motor but also for other hydraulic actuators (for example, a boom cylinder). In this case, the other hydraulic actuator is connected to the hydraulic pump via a control valve different from the swivel control valve. That is, the hydraulic pump is also used for supplying hydraulic oil to the swivel motor and supplying hydraulic oil to the other hydraulic actuators.

Further, Patent Document 1 further includes a swivel priority valve interposed between the hydraulic pump and the other hydraulic actuator, an electromagnetic proportional pressure control valve for changing the opening degree of the swivel priority valve, and a controller. Disclose what you have. The controller inputs a command to the electromagnetic proportional pressure control valve to reduce the opening degree of the swivel priority valve as the operation amount of the swivel lever increases. According to this device, when the operating amount of the swivel lever is small, the swivel priority valve is wide open to secure the flow rate of the hydraulic oil supplied to the arm cylinder, while when the operating amount of the swivel lever is large, the flow rate is secured. By narrowing the opening degree of the swivel priority valve, the operating pressure of the swivel motor is maintained high.

Japanese Unexamined Patent Publication No. 2005-325911

Since the swivel priority valve throttles the flow rate of the hydraulic oil supplied from the hydraulic pump to the other hydraulic actuator and causes a pressure loss, the throttle due to the decrease in the opening degree of the swivel priority valve is It is preferable that the execution is limited to an appropriate range as much as possible. However, if the opening degree of the swivel priority valve is simply changed depending on the amount of operation of the swivel lever as described above, the swivel priority valve can be throttled even when the swivel motor does not require a high operating pressure. There is a considerable possibility that the swivel priority valve will not be throttled even though the swivel motor requires a high operating pressure.

The present invention is a swivel hydraulic work machine in which a swivel motor that swivels an upper swivel body and other specific hydraulic actuators are connected to a common hydraulic pump, and operates on the swivel motor and the other hydraulic actuators. The purpose is to provide a product capable of proper distribution of oil.

The present inventors have focused on the turning speed of the upper turning body in order to achieve the object. That is, a high operating pressure of the swivel motor is required to generate a large swivel torque when the swivel speed of the upper swivel body having a large moment of inertia is increased from a low speed, and the swivel speed of the upper swivel body rises to some extent. Once you do, you don't need a lot of torque to maintain that turn.

The present invention has been made from this point of view. That is, the swivel hydraulic work machine provided by the present invention operates with a lower traveling body, an upper swivel body rotatably mounted on the lower traveling body, and a working device mounted on the upper swivel body. A swivel motor consisting of a hydraulic pump that discharges oil and a hydraulic motor that operates by receiving the supply of hydraulic oil discharged by the hydraulic pump, and capable of swiveling the upper swivel body according to the supply of the hydraulic oil. A swivel control valve that is interposed between the hydraulic pump and the swivel motor and opens and closes so as to change the swivel flow rate, which is the flow rate of hydraulic oil supplied from the hydraulic pump to the swivel motor, and the swivel control valve. A specific actuator other than the motor, which operates by receiving the supply of hydraulic oil discharged by the hydraulic pump, is interposed between the hydraulic pump and the specific actuator, and is provided from the hydraulic pump. An actuator flow limit valve that limits the actuator flow rate, which is the flow rate of hydraulic oil supplied to the specific actuator, and opens and closes to change the limit, and a swivel operation for commanding the operation of the swivel motor. The smaller the swivel speed detection unit that detects the swivel speed of the upper swivel body and the swivel speed detection unit that detects the swivel speed of the upper swivel body, and the swivel speed detection unit that detects the swivel speed when the swivel operation is given to the swivel operation member. It is provided with an actuator flow rate limiting unit that operates the actuator flow rate limiting valve so as to limit the actuator flow rate with a large degree of limitation.

In this swivel type hydraulic work machine, when the swivel speed of the upper swivel body is small during the swivel operation, that is, when there is a high possibility that acceleration of the swivel of the upper swivel body is required, the degree of limitation is large. By limiting the actuator flow rate and keeping the operating pressure of the swivel motor high, the swivel torque required for the acceleration is secured, while when the swivel speed is already high and the demand for acceleration is small, the limit degree of the actuator flow rate is reached. By suppressing (including the case where the limitation is released), it is possible to reduce the pressure loss due to the limitation of the actuator flow rate and perform highly efficient operation.

The concept of limiting the flow rate of the actuator does not exclude maintaining the non-supply state when the specific actuator does not need to be driven and the hydraulic oil is not originally supplied to the specific actuator. In other words, maintaining the state in which the hydraulic oil is not originally supplied to the specific actuator corresponds to limiting the actuator flow rate to zero.

It is preferable that the actuator flow rate limiting unit increases the flow rate limiting degree of the actuator flow rate corresponding to the turning speed as the turning operation given to the turning operation member is larger. This allows for more appropriate flow rate distribution that takes into account not only the turning speed but also the actual operator's willingness to accelerate turning.

Specifically, the actuator flow rate limiting unit is, for example, a maximum limiting degree setting unit that sets the maximum limiting degree that is the maximum value of the limiting degree, and the larger the turning operation is, the larger the maximum limiting degree is set. Based on the maximum limit set by the maximum limit setting unit, the limit characteristic is determined so that the limit decreases as the turning speed increases from the maximum limit, and the limit characteristic is set to the limit characteristic. A limit determination unit that determines the limit of the actuator flow rate corresponding to the turning speed, and a restriction operation that adjusts the opening degree of the actuator flow rate limiting valve based on the limit determined by the limit determination unit. Those having a portion and a portion are preferable. As a result, a preferable flow rate distribution control that takes into consideration both the turning speed and the magnitude of the turning operation is realized with a simple configuration.

The actuator flow rate limiting valve according to the present invention may be a dedicated valve for limiting the actuator flow rate, or may be a control valve for changing the actuator flow rate according to an operator's operation. Specifically, the specific actuator operating member that receives the specific actuator operation for commanding the operation of the specific actuator and the actuator flow rate are increased as the specific actuator operation given to the specific actuator operating member is larger. It is preferable to further include an actuator flow rate operating unit for opening the actuator flow rate limiting valve. As a result, it is possible to perform more appropriate flow rate distribution control in consideration of the operator's intention regarding the operation of the specific actuator with a simple configuration in which the actuator flow rate limiting valve is used as the control valve.

For example, when the actuator flow rate limiting valve is composed of a pilot-operated control valve that opens the valve in response to an input of pilot pressure, the actuator flow control unit operates the specific actuator given to the specific actuator operation member. It is preferable to include a specific actuator pilot valve that increases the pilot pressure input to the actuator flow rate limiting valve as the value increases. In this case, the actuator flow limiting unit is an electromagnetic valve interposed between the specific actuator pilot valve and the actuator flow limiting valve, and is a pilot input from the specific actuator pilot valve to the actuator flow limiting valve. It includes a pilot pressure reducing valve capable of operating to reduce the pressure, and a pressure reducing command unit for inputting a pressure reducing command signal to the pilot pressure reducing valve so that the pilot pressure is reduced as the turning speed is smaller. Therefore, it is possible to control the limiting of the actuator flow rate with a simple configuration using the pilot pressure input to the actuator flow rate limiting valve.

In this case, the solenoid valve constituting the pilot pressure reducing valve has a characteristic that the degree of pressure reduction of the pilot pressure increases as the pressure reducing command signal input to the solenoid valve increases, for example, an electromagnetic inverse proportional valve. Is preferable. This characteristic provides a state in which the specific actuator can be operated by the specific actuator operating member at a minimum even if the command signal input unit fails or the wire is disconnected and the command signal cannot be input. Guarantee.

As described above, according to the present invention, a swivel type hydraulic work machine in which a swivel motor for swiveling an upper swivel body and other specific hydraulic actuators are connected to a common hydraulic pump, the swivel motor and the swivel motor and the above. Those capable of properly distributing the hydraulic oil to other hydraulic actuators are provided.

It is a figure which shows the hydraulic excavator which is the hydraulic work machine which concerns on embodiment of this invention. It is a figure which shows the hydraulic circuit mounted on the said hydraulic excavator. It is a block diagram which shows the functional structure of the controller mounted on the said hydraulic excavator. It is a flowchart which shows the arithmetic control operation of the controller. FIG. 5 is a graph showing a maximum decompression degree map used by the maximum decompression degree determination unit of the controller to determine the maximum decompression degree Xmax corresponding to the swivel lever operation amount L. It is a graph which shows the decompression degree map which the decompression degree determination part of the controller uses to determine the decompression degree X based on the maximum decompression degree Xmax and the turning speed Ns of the upper swing body of the hydraulic excavator. It is a graph which shows the modification of the decompression degree map. It is a graph which shows the example of the time change of the turning speed Ns in the case where the boom 2nd speed flow rate limitation is performed by the controller, and the case where the limitation is not performed. It is a figure which shows the modification of the said hydraulic circuit.

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

FIG. 1 shows a hydraulic excavator according to the embodiment. It should be noted that the present invention can be widely applied not only to hydraulic excavators but also to work machines in which swivel drive is performed by flood control.

The hydraulic excavator is mounted on the lower traveling body 10 capable of traveling on the ground G, the upper rotating body 12 mounted on the lower traveling body 10 so as to be able to rotate around the vertical axis Z, and the upper rotating body 12. The working device 14 is provided. In the upper swivel body 12, the swivel body front-rear direction is set as the swivel body reference direction, the cab 16 which is an engine room is provided in the front side portion in the swivel body front-rear direction, and the work device 14 is mounted on the rear side. An engine room 18 is provided in the portion.

The working device 14 includes a boom 20, an arm 22, a bucket 24, and a plurality of telescopic hydraulic cylinders provided for driving the boom 20, that is, a boom cylinder 26, an arm cylinder 27, and a bucket cylinder 28. In this embodiment, the boom cylinder 26 that raises and lowers the boom 20 among the plurality of hydraulic cylinders corresponds to the "specific actuator" referred to in the present invention.

The boom 20 has a base end portion undulating at the front end of the upper swing body 12, that is, a base end portion rotatably supported around a horizontal axis, and a tip end portion on the opposite side thereof. The arm 22 has a base end portion rotatably attached to the tip end portion of the boom 20 about a horizontal axis and a tip end portion on the opposite side thereof, and the bucket 24 can be rotated to the tip end portion. Can be attached to. Each of the cylinders 26 to 28 operates in the expansion / contraction direction in response to the supply of hydraulic oil to rotate the drive target corresponding to the cylinder 26. For example, the boom cylinder 26 is interposed between the boom 20 and the upper swing body 12 so as to move the boom 20 in the raising direction and the lowering direction by its expansion and contraction.

FIG. 2 shows a portion of the hydraulic circuit mounted on the hydraulic excavator for causing the upper swing body 12 to perform a swivel operation and the boom 20 to perform an upward operation (boom raising operation). As shown in FIG. 2, the hydraulic circuit includes the boom cylinder 26 corresponding to the “specific actuator” as described above, the first main pump 31 which is a hydraulic pump connected to the output shaft of the engine 30, and the first main pump 31. The second main pump 32, the swing motor 36 which is a hydraulic motor for swinging the upper swing body 12, the boom 1-speed control valve 38, the boom 2-speed control valve 40, the swing control valve 42, and the boom. It includes a raising operation device 50, a boom lowering operation device (not shown), a left turning operation device 52A, and a right turning operation device 52B.

Each of the pumps 31, 32, and 34 is driven by the engine 30, thereby discharging the oil in the tank. The first and second main pumps 31 and 32 discharge hydraulic oil for directly moving the hydraulic actuator to be driven. The pilot pump 34 discharges pilot oil for supplying pilot pressure for opening and closing the control valves 38, 40, and 42.

The swivel motor 36 has an output shaft that rotates in response to the supply of the hydraulic oil, and the output shaft is connected to the upper swivel body 12 so as to swivel the upper swivel body 12 in both left and right directions. .. Specifically, the swivel motor 36 has a pair of ports 36a and 36b, and the output shaft rotates in the direction corresponding to the one port by receiving the supply of hydraulic oil to one of the ports. At the same time, the hydraulic oil is discharged from the other port.

Each of the control valves 38, 40, and 42 is composed of a hydraulic pilot-operated control valve, and by receiving the supply of pilot pressure from the pilot pump 34, the valve opens in a stroke corresponding to the magnitude of the pilot pressure. It operates, which allows hydraulic oil to be supplied to the corresponding hydraulic actuator at a flow rate corresponding to the pilot pressure. Therefore, the flow rate can be controlled by changing the pilot pressure.

The boom 1-speed control valve 38 is a valve that guides the hydraulic oil discharged from the first main pump 31 to the boom cylinder 26 as the main hydraulic oil for expanding and contracting the boom cylinder 26, and is the first valve. It is interposed between the main pump 31 and the boom cylinder 26. The boom 1-speed control valve 38 is composed of a pilot-operated control valve at three positions having a pair of pilot ports 39A and 39B, and is in a neutral position when the pilot pressure supplied to the pilot ports 39A and 39B is 0 or very small. It is kept at 38n and cuts off between the first main pump 31 and the boom cylinder 26. When a certain amount of pilot pressure or more is supplied to the pilot port 39A, the boom 1-speed control valve 38 shifts from the neutral position 38n to the boom raising position 38a with a stroke corresponding to the magnitude of the pilot pressure, and the boom At the raised position 38a, the hydraulic oil from the first main pump 31 is connected to the first main pump 31 so as to allow the hydraulic oil from the first main pump 31 to be supplied to the head side chamber 27A of the boom cylinder 26 at a flow rate corresponding to the stroke. A rod that connects the first pump line 35 and the head side chamber line 37A connected to the head side chamber 27A and is connected to the rod side chamber 27B so as to allow the hydraulic oil discharged from the rod side chamber 27B of the boom cylinder 26 to escape to the tank. A concubine line 37B is connected to the tank, which causes the boom cylinder 26 to operate in the extension direction, that is, the boom raising direction, at a speed corresponding to the stroke. On the contrary, when a pilot pressure equal to or higher than a certain level is supplied to the pilot port 39B, the boom 1-speed control valve 38 shifts from the neutral position 38n to the boom lowering position 38b with a stroke corresponding to the magnitude of the pilot pressure. At the boom lowering position 38b, the first pump line 35 and the first pump line 35 are allowed to be supplied to the rod side chamber 27B of the boom cylinder 26 at a flow rate corresponding to the stroke. The head side chamber line 37A is connected to the tank so as to connect the rod side chamber line 37B and allow the hydraulic oil discharged from the head side chamber 27A of the boom cylinder 26 to escape to the tank, whereby the boom cylinder. The 26 is operated in the contraction direction, that is, the boom lowering direction at a speed corresponding to the stroke.

The boom 2-speed control valve 40 and the swivel control valve 42 are interposed between the second main pump 32, the boom cylinder 26, and the swivel motor 36, respectively. In other words, the hydraulic oil discharged from the second main pump 32 passes through the boom 2-speed control valve 40 and the swivel control valve 42, respectively, to the head side chamber 27A of the boom cylinder 26 and the swivel motor 36. The distribution ratio is changed according to the opening degree of each of the control valves 40 and 42. Specifically, the swing control valve 42 is connected to the discharge port of the second main pump 32 via the second pump line 44, and the boom two-speed control valve 40 is a boom branching from the second pump line 44. It is connected to the 2-speed branch line 45.

The boom 2-speed control valve 40 is a valve corresponding to the "actuator flow rate limiting valve" in the present invention in this embodiment. Specifically, in addition to the hydraulic oil supplied to the boom cylinder 26 through the boom 1-speed control valve 38, the boom 2-speed control valve 40 is used to increase the speed of the boom 20 in the upward direction. Is guided from the second main pump 32 to the head side chamber 27A of the boom cylinder 26 corresponding to the specific actuator, and further, the boom second speed flow rate, which is the flow rate of the hydraulic oil, and the actuator flow rate referred to in the present invention. It is possible to open and close to change (restrict).

The boom 2-speed control valve 40 is a two-position pilot-operated control valve and has a single pilot port 41. The boom 2-speed control valve 40 is maintained at the neutral position 40n when the pilot pressure supplied to the pilot port 41 is 0 or minute, and shuts off between the second main pump 32 and the boom cylinder 26. When a pilot pressure equal to or higher than a certain level is supplied to the pilot port 41, the boom 2-speed control valve 40 shifts from the neutral position 40n to the boom raising speed increasing position 40a with a stroke corresponding to the magnitude of the pilot pressure. At the boom raising speed increasing position 40a, the boom second speed control valve 40 supplies hydraulic oil from the second main pump 32 to the head side chamber 27A of the boom cylinder 26 at a flow rate corresponding to the stroke. An oil passage that allows the above-mentioned, specifically, an oil passage that connects the boom 2-speed merging line 46 that joins the head side chamber line 37A and the boom 2-speed branch line 45, thereby forming the said The drive of the boom cylinder 26 in the raising direction is accelerated to a degree corresponding to the stroke.

The swivel control valve 42 selectively guides the hydraulic oil for driving the swivel motor 36 from the second main pump 32 to the first and second ports 36a and 36b of the swivel motor 36, and the swivel control valve 42. It is a valve that controls a swirling flow rate, which is the flow rate of hydraulic oil supplied to the motor 36.

The swivel control valve 42 is a pilot-operated control valve at three positions and has a pair of pilot ports 43A and 43B. The swivel control valve 42 is maintained at the neutral position 42n when the pilot pressures supplied to both pilot ports 43A and 43B are 0 or minute, and is between the second main pump 32 and the swivel motor 36. Cut off. When a pilot pressure equal to or higher than a certain level is supplied to the pilot port 43A, the swivel control valve 42 shifts from the neutral position 42n to the left swivel position 42a with a stroke corresponding to the magnitude of the pilot pressure, and the swivel control valve 42 shifts to the left swivel position 42a. In 42a, the second pump line 44 and the first one are allowed to be supplied to the first port 36a of the swing motor 36 at a flow rate corresponding to the stroke. A first motor line 48A connected to the port 36a is connected, whereby the swivel motor 36 is operated in the left swivel direction at a speed corresponding to the stroke. On the contrary, when a pilot pressure equal to or higher than a certain level is supplied to the pilot port 43B, the swivel control valve 42 shifts from the neutral position 42n to the right swivel position 42b with a stroke corresponding to the magnitude of the pilot pressure. At the right turning position 42b, the turning supply line allows the hydraulic oil from the second main pump 32 to be supplied to the second port 36b of the turning motor 36 at a flow rate corresponding to the stroke. The 48 is connected to the second motor line 48B connected to the second port 36b, whereby the swivel motor 36 is operated in the right swivel direction at a speed corresponding to the stroke.

The boom raising operation device 50 is a device used by an operator to command a boom raising operation of the boom cylinder 26 in the cab 16, and includes a boom raising lever 53 and a boom raising pilot valve 54. ..

The boom raising lever 53 corresponds to a specific actuator operating member. The boom raising operation (specific actuator operation), which is an operation for instructing the boom raising lever 53 to operate the boom cylinder 26 corresponding to the specific actuator (the boom raising operation in this embodiment) as described above, for example. The rotation operation is given by the operator.

The boom raising pilot valve 54 is connected to the boom raising lever 53 so as to open in conjunction with the boom raising operation given to the boom raising lever 53. The boom raising pilot valve 54 is interposed between the pilot pump 34 and the pilot port 39A, and a pilot pressure corresponding to the magnitude of the boom raising operation is boomed to the pilot port 39A of the boom 1st speed control valve 38. It operates to supply through the raised pilot line 66. Specifically, the boom raising pilot valve 54 maintains a valve closed state that shuts off between the pilot pump 34 and the pilot port 39A when the boom raising lever 53 is not operated and is in the neutral position. When the boom raising lever 53 is rotated from the neutral position (that is, the boom raising lever 53 is given the boom raising operation), the amount of the rotating operation (the magnitude of the boom raising operation) with respect to the pilot port 39A. ), The valve is opened with a stroke that supplies a pilot pressure of a magnitude corresponding to). That is, the boom raising pilot valve 54, together with the boom raising pilot line 66, increases the boom 2nd speed flow rate (actuator flow rate) as the boom raising operation (specific actuator operation) increases. It constitutes an actuator flow rate control part which operates.

On the other hand, the boom lowering operation device (not shown) has a boom lowering lever that receives the boom lowering operation and a boom lowering pilot valve connected to the boom lowering lever. The boom lowering pilot valve is interposed between the pilot pump 34 and the pilot port 39B so as to supply a pilot pressure corresponding to the magnitude of the boom lowering operation to the pilot port 39B of the boom 1st speed control valve 38. do.

The left turn operation device 52A and the right turn operation device 52B are devices used by an operator to command a left turn operation and a right turn operation of the turn motor 36 in the cab 16, respectively. The left turn operation device 52A has a left turn lever 55A and a left turn pilot valve 56A, and the right turn operation device 52B has a right turn lever 55B and a right turn pilot valve 56B.

The left-turning and right-turning levers 55A and 55B correspond to the turning operation members, respectively, and the left-turning and right-turning levers 55A and 55B have the left-turning operation and the right-handed movement of the turning motor 36, respectively. The operator gives a left turn operation and a right turn operation, which are operations for commanding the previous operation.

The left turning pilot valve 56A is connected to the left turning lever 55A so as to open in conjunction with the left turning operation given to the left turning lever 55A, and corresponds to the magnitude of the left turning operation. It is interposed between the pilot pump 34 and the pilot port 43A so as to supply the pilot pressure to the pilot port 43A of the swing control valve 42. Similarly, the right-handed turning pilot valve 56B is connected to the right-handed turning lever 55B so as to open in conjunction with the right-handed turning operation given to the right-handed turning lever 55B, and is connected to the right-handed turning lever 55B. It is interposed between the pilot pump 34 and the pilot port 43B so as to supply the pilot pressure corresponding to the magnitude of the turning operation to the pilot port 43B of the turning control valve 42.

Specifically, the left swivel pilot valve 56A maintains a closed state in which the pilot pump 34 and the pilot port 43A are shut off when the left swivel lever 55A is not operated and is in the neutral position. When the left turning lever 55A is rotated from the neutral position (that is, the left turning lever 55A is given a left turning operation), the amount of the rotation operation with respect to the pilot port 43A (the magnitude of the left turning operation). The valve is opened with a stroke that supplies a pilot pressure of a size corresponding to. Similarly, the right-handed turning pilot valve 56B maintains a closed valve state that shuts off between the pilot pump 34 and the pilot port 43B when the right-handed turning lever 55B is in the neutral position without being operated. When the right-handed turning lever 55B is rotated from the neutral position (that is, the right-handed turning lever 55B is given a right-handed turning operation), the amount of the rotation operation (right-handed turning) with respect to the pilot port 43B. The valve is opened with a stroke that supplies a pilot pressure of a size corresponding to the size of the operation).

The hydraulic excavator according to this embodiment further includes a plurality of sensors shown in FIGS. 2 and 3. The plurality of sensors include a boom raising pilot pressure sensor 60, a left turning pilot pressure sensor 62A, a right turning pilot pressure sensor 62B, and a turning angle sensor 64.

The boom raising pilot pressure sensor 60 detects a boom raising pilot pressure Pb which is a pilot pressure supplied from the boom raising operation device 50 to the pilot port 38A of the boom 1st speed control valve 38, and detects an electric signal, that is, a boom pilot pressure. It is a pressure sensor that converts it into a detection signal.

The turning pilot pressure sensors 62A and 62B are left turning pilot pressure and right turning pilot pressure which are pilot pressures supplied from the left turning and right turning operating devices 52A and 52B to the pilot ports 43A and 43B of the turning control valve 42, respectively. It is a pressure sensor that detects the rotation pilot pressure, and generates a turning pilot pressure detection signal that is an electric signal corresponding to the pilot pressure.

The swivel angle sensor 64 is a pressure sensor that detects the rotation phase of the swivel motor 36, thereby detecting the swivel angle of the upper swivel body 12 corresponding to the rotation phase, and is the rotation phase (swivel angle). Generates a turning angle detection signal, which is an electric signal corresponding to.

The features of the hydraulic excavator according to this embodiment are a swivel speed detection unit that detects the swivel speed of the upper swivel body 12, a boom 2nd speed flow rate limiting unit corresponding to the actuator flow rate limiting unit according to the present invention, and a boom 2nd speed flow rate limiting unit. Further prepare. The boom 2nd speed flow rate limiting unit has a small turning speed detected by the turning speed detecting unit during a turning operation in which any of the left turning and right turning levers 55A and 55B, which are turning operation members, is given a turning operation. The actuator flow rate has a moderately large limit, and in this embodiment, the hydraulic oil supplied from the second main pump 32 to the head side chamber 27A of the boom cylinder 26 through the boom 2-speed control valve 40 which is an actuator flow rate limiting valve. The boom 2-speed control valve 40 is operated so as to limit the boom 2-speed flow rate, which is the flow rate.

Specifically, the hydraulic excavator according to this embodiment further includes a pilot pressure reducing valve 68 and a controller 70 shown in FIGS. 2 and 3.

The pilot pressure reducing valve 68 is interposed between the boom 2-speed control valve 40, which is an actuator flow limiting valve, and the boom-raising pilot valve 54, which is a pilot valve for the boom 2-speed control valve 40, and the boom. It operates so as to reduce the boom raising pilot pressure input from the raising pilot valve 54 to the boom 2-speed control valve. Specifically, the pilot pressure reducing valve 68 is composed of a solenoid valve having a solenoid 69, and is provided in the middle of a boom raising pilot line 66 from the boom raising pilot valve 54 to the pilot port 41 of the boom 2nd speed control valve 40. ..

In this embodiment, the solenoid valve constituting the pilot pressure reducing valve 68 has a characteristic that the larger the pressure reducing command signal (pressure reducing command current) input to the solenoid 69, the larger the pressure reducing degree to reduce the boom raising pilot pressure. , For example, an electromagnetic inverse proportional valve. The solenoid valve may have a characteristic that the degree of decompression decreases as the decompression command signal increases, for example, an electromagnetic direct proportional valve, but as described above, the decompression degree increases as the decompression command signal increases. The use of the solenoid valve with the above can guarantee the operation of the boom cylinder 26 by operating the boom raising lever 53 at a minimum even when the input of the decompression command signal becomes impossible due to a failure or disconnection of the controller 70. Brings the benefits you can.

The controller 70 has a maximum decompression degree setting unit 72 as shown in FIG. 3, a turning speed calculation unit 74, and a decompression degree as functions for configuring the turning speed detecting unit and the boom 2nd speed flow rate limiting unit. It has a determination unit 76 and a decompression command unit 78.

The maximum decompression degree setting unit 72 sets the maximum decompression degree Xmax (%), which is the maximum value of the decompression degree X in the pilot pressure reducing valve 68, and the left turning lever 55A or the right turning lever 55B is used. The larger the given turning operation (left turning operation or right turning operation), the larger the maximum limit Xmax is set. The decompression degree X is a degree at which the boom raising pilot pressure supplied from the boom raising pilot valve 54 to the pilot port 41 of the boom 2-speed control valve 40 is reduced by the pilot pressure reducing valve 68, and is based on the actuator flow rate. It corresponds to the "limitation degree" which is the degree of limiting the flow rate of a certain boom 2nd speed. The maximum decompression degree Xmax therefore corresponds to the "maximum limit" referred to in the present invention. An example of a specific method for setting the maximum decompression degree Xmax will be described later.

The turning speed calculation unit 74 calculates the turning speed (rotation speed per minute in this embodiment) Ns (rpm) by the differential calculation of the turning angle detected by the turning angle sensor 64. Therefore, the turning speed calculation unit 74 constitutes the turning speed detection unit together with the turning angle sensor 64.

The decompression degree determination unit 76 is such that the decompression degree X decreases as the turning speed Ns increases from the maximum decompression degree Xmax based on the maximum decompression degree Xmax set by the maximum decompression degree setting unit 72. The decompression degree characteristic is determined, and the decompression degree X corresponding to the turning speed Ns is determined based on the decompression degree characteristic. A specific method for determining the decompression degree characteristic and the decompression degree X will also be described later.

The decompression command unit 78 is a command signal (command current) for adjusting the opening degree of the pilot pressure reducing valve 68 to an opening degree that realizes the decompression degree X determined by the decompression degree determination unit 76, that is, the said. A command signal for reducing the boom raising pilot pressure as the turning speed Ns is smaller is input to the solenoid 69 of the pilot pressure reducing valve 68. Therefore, the pilot pressure reducing valve 68 and the pressure reducing command unit 78 constitute a limiting operation unit that adjusts the opening degree of the boom 2-speed control valve 40 based on the pressure reducing degree X determined by the pressure reducing degree determining unit 76. do.

Next, a specific arithmetic control operation performed by the controller 70 and the operation of each element accompanying the operation will be described with reference to the flowchart of FIG. 4 and the graphs of FIGS. 5 to 8.

The maximum decompression degree setting unit 72 and the decompression degree determination unit 76 of the controller 70 first determine whether or not the left turn and right turn levers 55A and 55B, which are the turn operation members, are given a turn operation, and the specific actuator operation member. It is determined whether or not the boom raising operation is given to the boom raising lever 53 (steps S1 and S2).

When neither the left turning lever nor the right turning lever 55A or 55B is given a turning operation (NO in step S1), or when the boom raising lever 53 is not given a boom raising operation (NO in step S2). ), That is, when the simultaneous combined operation of the turning operation and the boom raising operation is not performed, it is not necessary to control the distribution of the flow rate of the hydraulic oil discharged from the second main pump 32, so that the controller 70 is a pilot. The boom raising pilot pressure is not reduced by the pressure reducing valve 68. Specifically, the maximum decompression degree setting unit 72 does not set the maximum decompression degree Xmax, and the decompression degree determination unit 76 sets the pilot pressure decompression degree X to 0% (step S3), and in response to this, the decompression command unit 78 inputs the minimum depressurization command current (including the case of 0) to the solenoid 69 of the pilot decompression valve 68 (step S4).

Therefore, when the boom raising lever 53 is not given the boom raising operation and the turning operation is given to any of the swivel levers 55A and 55B, the hydraulic oil discharged from the second main pump 32 is directly sent to the swivel motor 36. While being supplied, the boom 2-speed control valve 40 is held in a closed state, that is, a state in which the actuator flow rate is not generated. As described above, even when the actuator flow rate is originally set to 0, the operation of keeping the actuator flow rate at 0 is included in the operation of limiting the actuator flow rate.

On the contrary, when the boom raising operation is given to the boom raising lever 53 without giving the turning operation to any of the turning levers 55A and 55B, the boom raising pilot pressure corresponding to the magnitude of the boom raising operation remains as it is. It is input from the boom raising pilot valve 54 (without depressurization) to the pilot port 41 of the boom 2-speed control valve 40. That is, hydraulic oil is supplied to the head side chamber 27A of the boom cylinder 26 from the first main pump 31 through the boom 1-speed control valve 38 at a boom 1-speed flow rate corresponding to the magnitude of the boom raising operation. In addition, the hydraulic oil for speeding up is also supplied from the second main pump 32 at the boom 2nd speed flow rate that directly corresponds to (that is, is not limited to) the magnitude of the boom raising operation. As a result, the boom raising operation at a speed that meets the operator's request is realized.

When a turning operation is given to any of the left turning and right turning levers 55A and 55B (YES in step S1) and a boom raising operation is given to the boom raising lever 53 (NO in step S2), that is, turning. When a combined operation is performed for both the operation and the boom raising operation, the controller 70 distributes the flow rate of the hydraulic oil discharged from the second main pump 32 to the swivel motor 36 and the boom cylinder 26 which is a specific actuator. To perform control of.

First, the maximum decompression degree setting unit 72 of the controller 70 is the maximum corresponding to the magnitude of the turning operation actually given to the left turning lever 55A or the right turning lever 55B, that is, the turning lever operation amount L1. The degree of decompression X1max is set (step S5). For the setting of the maximum decompression degree X1max, for example, as shown in FIG. 5, the maximum decompression degree map stored in advance in the maximum decompression degree setting unit 72 regarding the relationship between the swivel lever operation amount L and the maximum decompression degree Xmax is obtained. It is done by using. That is, the maximum decompression degree setting unit 72 sets the maximum decompression degree Xmax as the swivel lever operation amount L increases.

The maximum decompression degree Xmax may be calculated based on a relational expression given in advance regarding the relationship between the swivel lever operation amount L and the maximum decompression degree Xmax, instead of the map as shown in FIG. Further, the characteristic of the maximum decompression degree Xmax with respect to the swivel lever operating amount L is not limited to a linear one as shown in FIG. 5, but may be a curved one.

Next, the decompression degree determination unit 76 of the controller 70 determines a decompression degree map corresponding to the maximum decompression degree X1max set by the maximum decompression degree setting unit 72, and the turning speed threshold value Nsa is based on the decompression degree map. Is determined (step S6).

The decompression degree map is created for the relationship between the turning speed Ns detected by the turning speed detection unit and the pilot pressure decompression degree X. For example, as shown in FIG. 6, the turning speed Ns is increased. Along with this, the pilot pressure decompression degree X has a characteristic of gradually decreasing from the maximum decompression degree Xmax. The characteristic is not limited to a linear one as shown in FIG. 6, but may be a curved one as shown in FIG. 7, for example.

The method for determining the decompression degree map is also not particularly limited. The decompression degree determination unit 76 according to this embodiment stores a plurality of decompression degree maps corresponding to each of the plurality of preset ranges for the maximum decompression degree Xmax, and is as described above among the plurality of ranges. The decompression degree map corresponding to the range to which the maximum decompression degree X1max set based on the swivel lever operation amount L1 belongs is selected as the decompression degree map to be used.

The characteristic of the turning speed Ns − decompression degree X1 corresponding to the maximum decompression degree Xmax may be determined by using a predetermined relational expression (characteristic expression). For example, the following equations (1) and (2) are relational expressions corresponding to the characteristics of the decompression degree maps shown in FIGS. 6 and 7, respectively, and these relational expressions also correspond to the maximum decompression degree Xmax and the turning speed. It is possible to set the characteristics of the degree of decompression X with respect to Ns.

X =-(Xmax / Nsa) * Ns + Xmax ... (1)
X = (Xmax / Nsa ² ) * (Ns-Nsa) ² ... (2)
In these equations, Nsa is the value of the turning speed Ns that makes the pilot decompression degree X 0 (X intercept in the characteristic expressed by the linear function as shown in FIG. 6 and equation (1)), and this value is It corresponds to the turning speed threshold value. Therefore, if the characteristic of the turning speed Ns-decompression degree X corresponding to the maximum decompression degree X1max (the decompression degree map or the relational expression) is determined, the turning speed threshold value Nsa corresponding to the characteristic is inevitably determined. The turning speed threshold value Nsa is the minimum value of the turning speed Ns that does not require decompression of the boom raising pilot pressure, in other words, the maximum value of the turning speed Ns that requires the decompression.

The decompression degree determining unit 76 compares the actual turning speed Ns1 detected by the turning speed detecting unit with the turning speed threshold value Nsa (step S7).

When the actual turning speed Ns1 is equal to or higher than the turning speed threshold value Nsa (NO in step S7), that is, since the actual turning speed Ns1 is sufficiently high and the required turning torque is small, it is not necessary to limit the flow rate of the boom 2nd speed. If there is, the decompression degree determination unit 76 sets the pilot decompression degree X to 0% as in the case of the turning independent operation or the boom raising independent operation (step S3). Correspondingly, the decompression command unit 78 inputs the minimum decompression command current to the solenoid 69 of the pilot pressure reducing valve 68 (step S4).

On the other hand, when the actual turning speed Ns1 is less than the turning speed threshold value Nsa (YES in step S7), that is, when the actual turning speed Ns1 is low and a large turning torque is required to accelerate the turning of the upper turning body 12. The decompression degree determination unit 76 determines the pilot pressure decompression degree X1 for limiting the boom 2nd speed flow rate in order to secure the turning torque. Specifically, the pilot decompression degree X1 is determined based on the decompression degree map selected in step S6 (that is, corresponding to the maximum decompression degree X1max set in step S5) and the actual turning speed Ns1. Correspondingly, the decompression command unit 78 sets the decompression command current corresponding to the pilot pressure decompression degree X1, that is, the opening degree of the pilot decompression valve 68 to the opening degree for realizing the pilot pressure decompression degree X1. Is input to the solenoid 69 of the pilot pressure reducing valve 68 (step S9). As a result, a boom raising pilot pressure lower than the pilot pressure output from the boom raising pilot valve 54 is input to the pilot port 41 of the boom 2nd speed control valve 40, and the opening area of the boom 2nd speed control valve 40 is correspondingly increased. Is squeezed.

In this way, the boom 2nd speed flow rate is limited by the limit degree corresponding to the turning speed Ns1, and the control that enables sufficient turning acceleration of the upper turning body 12 is achieved. FIG. 8 shows the time change of the turning speed Ns with respect to the case where the boom 2nd speed flow rate, which is the actuator flow rate, is not limited, and the case where the limitation is performed according to the turning speed Ns as in the embodiment. It is a graph shown by lines 80 and 82. As shown in this graph, the limitation of the boom second speed flow rate until the turning speed Ns reaches the turning speed threshold value Nsa contributes to enhancing the initial acceleration of the turning of the upper turning body 12. On the other hand, reducing the degree of limitation on the increase in the turning speed Ns reduces the pressure loss in the boom 2-speed control valve 40 and enables highly efficient operation.

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

(A) Consideration of turning operation In the above embodiment, the larger the turning operation given to the turning operation member (left turning lever 55A or right turning lever 55B), the larger the actuator flow rate (boom 2nd speed) corresponding to the turning speed Ns. Control is performed to increase the flow rate limit of (flow rate), but in the present invention, the flow rate limit may be set based only on the turning speed regardless of the magnitude of the turning operation. However, the control considering the magnitude of the turning operation enables more appropriate distribution of the flow rate in consideration of the actual operator's intention of turning acceleration.

Further, the method of considering the magnitude of the turning operation is not limited to the setting of the maximum limit degree (maximum decompression degree Xmax in the embodiment) according to the magnitude of the turning operation as described above. For example, by multiplying the pilot pressure decompression degree X given the characteristics shown in FIG. 6 or 7 by a correction coefficient that increases or decreases according to the magnitude of the turning operation, the magnitude of the turning operation can also be increased. It is possible to realize the control in consideration of the coefficient.

(B) Actuator flow rate limiting valve The actuator flow rate limiting valve according to the present invention, that is, a valve that limits the actuator flow rate by interposing between the hydraulic pump and the specific actuator, is not limited to the boom 2-speed control valve 40. The actuator flow rate limiting valve may be, for example, the boom 1-speed control valve 38 shown in FIG. That is, even if the swivel motor 36 is connected to the second main pump 32 via the swivel control valve 42 and the boom cylinder 26 is connected in parallel with the swivel motor 36 via the boom 1-speed control valve 38. good. In this case as well, the actuator flow rate (in this case, the boom 1st speed flow rate) is reduced by reducing the pilot pressures (boom raising pilot pressure and boom lowering pilot pressure) input to the pilot ports 39A and 39B of the boom 1st speed control valve 38, respectively. It is possible to limit.

Further, the actuator flow rate limiting valve is a control valve that is pilot-operated in response to a specific actuator operation (boom raising operation in the embodiment) such as the boom 2-speed control valve 40 and the boom 1-speed control valve 38. Not limited. The actuator flow rate limiting valve may be a dedicated valve for limiting the actuator flow rate independently of the specific actuator operation.

An example thereof is shown in FIG. In the flood control circuit shown in FIG. 9, a boom 2-speed flow rate limiting valve 90 dedicated to flow rate limiting is added as the actuator flow rate limiting valve to the flood control circuit shown in FIG. 2, and a pilot pressure reducing valve replaces the pilot pressure reducing valve 68. 88 is added.

The boom 2-speed flow rate limiting valve 90 is provided on the upstream side of the boom 2-speed control valve 40 in the boom 2-speed branch line 45. Like the boom 2-speed control valve 40, the boom 2-speed flow rate limiting valve 90 is composed of a pilot-operated control valve at two positions having a single pilot port 91, and the pilot port 91 is the boom. It is connected to the pilot pump 34 via a dedicated flow rate limiting pilot line 86 independent of the 2-speed pilot line 66. The boom 2-speed flow rate control valve 90 has a fully open position 90n and a flow rate limiting position 90a, and when no pilot pressure is input to the pilot port 91, the boom 2-speed branch line 45 is held at the fully open position 90n. When the pilot pressure is input to the pilot port 91, the flow rate is shifted to the flow rate limiting position 90a with a stroke corresponding to the magnitude of the pilot pressure, and the flow rate of the hydraulic oil is set at the flow rate limiting degree corresponding to the stroke. (Boom 2nd speed flow rate) is limited.

The pilot pressure reducing valve 88 is composed of a solenoid valve like the pilot pressure reducing valve 68 and has a solenoid 89. The electromagnetic valve has a larger pressure reducing command signal (pressure reducing command current) input to the solenoid 89. A valve having a characteristic of reducing the degree of decompression, for example, a solenoid direct proportional valve.

Also in this hydraulic circuit, the smaller the turning speed detected by the turning speed detection unit, the larger the pressure reducing command signal input to the solenoid 89 of the pilot pressure reducing valve 88 and the larger the turning speed command signal is input to the boom 2nd speed flow rate limiting valve 90. Flow rate limitation By increasing the pilot pressure, it is possible to limit the boom 2nd speed flow rate, which is the actuator flow rate.

(C) Specific actuator The specific actuator according to the present invention is a hydraulic actuator other than the swivel motor and can be arbitrarily selected from the hydraulic actuators mounted on the work machine. For example, in the hydraulic excavator shown in FIG. 1, the arm cylinder 28 may be selected as the specific actuator.

10 Lower traveling body 12 Upper rotating body 14 Working device 20 Boom 26 Boom cylinder (specific actuator)
27A Head side chamber 32 2nd main pump (hydraulic pump)
36 Swing motor 40 Boom 2-speed control valve (actuator flow rate limiting valve)
41 Pilot port 42 Swing control valve 50 Boom raising operation device 52A Left turning operation device 52B Right turning operation device 53 Boom raising lever (specific actuator operating member)
54 Boom raising pilot valve (specific actuator pilot valve)
55A Left swivel lever (swivel operation member)
55B Right swivel lever (swivel operation member)
60 Boom raising pilot pressure sensor 62A Left turning pilot pressure sensor 62B Right turning pilot pressure sensor 64 Turning angle sensor (consisting of turning speed detection unit)
68, 88 Pilot pressure reducing valve 70 Controller 72 Maximum decompression degree setting unit 74 Swivel speed calculation unit (composed of swirl speed detection unit)
76 Decompression degree determination unit 78 Decompression command unit 90 Boom 2-speed flow limiting valve

Claims (5)

It is a swivel type hydraulic work machine.
With the lower running body,
An upper swivel body that is mounted on the lower traveling body so as to be swivel
The work device mounted on the upper swivel body and
A hydraulic pump that discharges hydraulic oil and
A swivel motor consisting of a hydraulic motor that operates by receiving the supply of hydraulic oil discharged by the hydraulic pump and capable of swiveling the upper swivel body according to the supply of the hydraulic oil, and a swivel motor.
A swivel control valve that is interposed between the hydraulic pump and the swivel motor and operates to open and close so as to change the swirl flow rate, which is the flow rate of hydraulic oil supplied from the hydraulic pump to the swivel motor.
A specific actuator that is different from the swivel motor and operates by receiving the supply of hydraulic oil discharged by the hydraulic pump.
An actuator flow rate limiting valve that is interposed between the hydraulic pump and the specific actuator and operates to open and close so as to change the actuator flow rate, which is the flow rate of hydraulic oil supplied from the hydraulic pump to the specific actuator.
A swivel operation member to which a swivel operation for commanding the operation of the swivel motor is given, and
A swivel speed detection unit that detects the swivel speed of the upper swivel body,
The actuator flow rate that operates the actuator flow rate limiting valve so as to limit the actuator flow rate with a larger limit as the turning speed detected by the turning speed detection unit becomes smaller during the turning operation in which the turning operation is applied to the turning operation member. for example Bei and the limiting portion, the,
The actuator flow rate limiting unit is configured so that the larger the turning operation given to the turning operation member, the larger the flow rate limiting degree of the actuator flow rate corresponding to the turning speed.
The actuator flow rate limiting unit is a maximum limiting degree setting unit that sets a maximum limiting degree that is the maximum value of the limiting degree, and sets a larger maximum limiting degree as the turning operation is larger, and the maximum limiting degree setting. Based on the maximum limit set by the unit, the limit characteristic is determined so that the limit decreases as the turning speed increases from the maximum limit, and the turning speed is determined based on the limit characteristic. It has a limit degree determination unit that determines the corresponding limit degree of the actuator flow rate, and a limit operation unit that adjusts the opening degree of the actuator flow rate limit valve based on the limit degree determined by the limit degree determination unit. Swivel hydraulic work machine. It is a swivel type hydraulic work machine.
With the lower running body,
An upper swivel body that is mounted on the lower traveling body so as to be swivel
The work device mounted on the upper swivel body and
A hydraulic pump that discharges hydraulic oil and
A swivel motor consisting of a hydraulic motor that operates by receiving the supply of hydraulic oil discharged by the hydraulic pump and capable of swiveling the upper swivel body according to the supply of the hydraulic oil, and a swivel motor.
A swivel control valve that is interposed between the hydraulic pump and the swivel motor and operates to open and close so as to change the swirl flow rate, which is the flow rate of hydraulic oil supplied from the hydraulic pump to the swivel motor.
A specific actuator that is different from the swivel motor and operates by receiving the supply of hydraulic oil discharged by the hydraulic pump.
An actuator flow rate limiting valve that is interposed between the hydraulic pump and the specific actuator and operates to open and close so as to change the actuator flow rate, which is the flow rate of hydraulic oil supplied from the hydraulic pump to the specific actuator.
A swivel operation member to which a swivel operation for commanding the operation of the swivel motor is given, and
A swivel speed detection unit that detects the swivel speed of the upper swivel body,
The actuator flow rate that operates the actuator flow rate limiting valve so as to limit the actuator flow rate with a larger limit as the turning speed detected by the turning speed detection unit becomes smaller during the turning operation in which the turning operation is applied to the turning operation member. Restriction part and
A specific actuator operating member that receives a specific actuator operation for commanding the operation of the specific actuator, and a specific actuator operating member.
An actuator flow rate operating unit that opens the actuator flow rate limiting valve so that the larger the specific actuator operation given to the specific actuator operating member is, the larger the actuator flow rate is provided.
The actuator flow rate limiting valve is composed of a pilot-operated control valve that opens the valve by receiving an input of pilot pressure.
The actuator flow rate control unit includes a specific actuator pilot valve that increases the pilot pressure input to the actuator flow rate limiting valve as the specific actuator operation given to the specific actuator operation member increases.
The actuator flow rate limiting unit is a solenoid valve interposed between the specific actuator pilot valve and the actuator flow rate limiting valve, and reduces the pilot pressure input from the specified actuator pilot valve to the actuator flow rate limiting valve. A swivel-type hydraulic work machine including a pilot pressure reducing valve capable of operating the engine and a pressure reducing command unit for inputting a pressure reducing command signal to the pilot pressure reducing valve so that the pilot pressure is reduced as the turning speed is smaller. .. The swivel type hydraulic work machine according to claim 2 , wherein the actuator flow rate limiting unit increases the flow rate limiting degree of the actuator flow rate corresponding to the swivel speed as the swivel operation given to the swivel operation member is larger. A swivel type hydraulic work machine configured as. The swivel hydraulic work machine according to claim 3 , wherein the actuator flow rate limiting unit is a maximum limiting degree setting unit that sets a maximum limiting degree which is the maximum value of the limiting degree, and the larger the swivel operation is, the larger it is. Based on the one that sets the maximum limit and the maximum limit set by the maximum limit setting unit, the limit characteristic that the limit decreases as the turning speed increases from the maximum limit is provided. The limit degree determination unit that determines and determines the limit degree of the actuator flow rate corresponding to the turning speed based on the limit degree characteristic, and the actuator flow rate limit valve based on the limit degree determined by the limit degree determination unit. Has a limiting operation unit for adjusting the opening degree of
Swivel type hydraulic work machine. The swivel type hydraulic work machine according to any one of claims 2 to 4, wherein the solenoid valve constituting the pilot pressure reducing valve has a degree of pressure reduction of the pilot pressure as the pressure reducing command signal input to the solenoid valve becomes larger. A swivel type hydraulic work machine that has the property of increasing the size.

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