Patent Description:
A shovel that increases the flow rate of hydraulic oil flowing into a swing hydraulic motor by reducing the flow rate of hydraulic oil flowing into an arm cylinder when performing excavation with a complex operation including a swing operation and an arm closing operation has been known (see Patent Document <NUM>).

This excavation is typically excavation achieved by closing an arm while pressing the side of a bucket against an object of excavation (also referred to as "swing and press excavation").

This shovel can prevent the pressing force generated by the swing hydraulic motor from being insufficient by supplying hydraulic oil preferentially to the swing hydraulic motor. Therefore, an operator of this shovel can smoothly perform such excavation as described above.

Furthermore, a working machine is known comprising a controller in which the relationship between a pump delivery pressure and a target opening area of a variable throttle of a control valve is set such that the target opening area is large when the pump delivery pressure is low, and vice versa (see Patent Document <NUM>).

Patent Document <NUM> discloses a shovel with a controller that increases the pressure of the hydraulic fluid that can flow into a boom cylinder in accordance with information pertaining to an attachment before performing a boom raising operation.

The above-described shovel, however, may reduce the flow rate of hydraulic oil flowing into the arm cylinder to destabilize the motion of the arm when a complex operation including a swing operation and an arm closing operation is performed without the side of the bucket contacting an object of excavation as well.

Therefore, it is desired to stabilize the motion of a shovel when a complex operation including a swing operation is performed.

The aforementioned objective is achieved by a shovel according to claim <NUM>.

A shovel according to an embodiment of the present invention includes a lower traveling structure, an upper swing structure swingably mounted on the lower traveling structure, a first hydraulic pump provided on the upper swing structure, an attachment attached to the upper swing structure, a first actuator, a second actuator, a first directional control valve corresponding to the first actuator, a second directional control valve corresponding to the second actuator, a first conduit connecting the first hydraulic pump and the first directional control valve, a second conduit connecting the first conduit and the second directional control valve, a control valve installed in the second conduit, and a control device configured to control the opening area of the control valve according to information on work details.

The above-described means makes it possible to stabilize the motion of a shovel when a complex operation including a swing operation is performed.

First, a shovel <NUM> serving as an excavator according to an embodiment of the present invention is described with reference to <FIG> and <FIG>. <FIG> is a side view of the shovel <NUM>. <FIG> is a plan view of the shovel <NUM>.

According to this embodiment, a lower traveling structure <NUM> of the shovel <NUM> includes crawlers 1C. The crawlers 1C are driven by travel hydraulic motors <NUM> serving as travel actuators mounted on the lower traveling structure <NUM>. Specifically, the crawlers 1C include a left crawler 1CL and a right crawler 1CR. The left crawler 1CL is driven by a left travel hydraulic motor <NUM>. The right crawler 1CR is driven by a right travel hydraulic motor 2MR.

An upper swing structure <NUM> is swingably mounted on the lower traveling structure <NUM> via a swing mechanism <NUM>. The swing mechanism <NUM> is driven by a swing hydraulic motor 2A serving as a swing actuator mounted on the upper swing structure <NUM>.

A boom <NUM> is attached to the upper swing structure <NUM>. An arm <NUM> is attached to the distal end of the boom <NUM>. A bucket <NUM> serving as an end attachment is attached to the distal end of the arm <NUM>. The boom <NUM>, the arm <NUM>, and the bucket <NUM> constitute an excavation attachment AT that is an example of an attachment. The boom <NUM> is driven by a boom cylinder <NUM>. The arm <NUM> is driven by an arm cylinder <NUM>. The bucket <NUM> is driven by a bucket cylinder <NUM>. The boom cylinder <NUM>, the arm cylinder <NUM>, and the bucket cylinder <NUM> constitute an attachment actuator.

The boom <NUM> is supported to be pivotable upward and downward relative to the upper swing structure <NUM>. A boom angle sensor S1 is attached to the boom <NUM>. The boom angle sensor S1 can detect a boom angle θ1 that is the pivot angle of the boom <NUM>. The boom angle θ1 is, for example, a rise angle from the lowest position of the boom <NUM>. Therefore, the boom angle θ1 is maximized when the boom <NUM> is raised most.

The arm <NUM> is pivotably supported relative to the boom <NUM>. An arm angle sensor S2 is attached to the arm <NUM>. The arm angle sensor S2 can detect an arm angle θ2 that is the pivot angle of the arm <NUM>. The arm angle θ2 is, for example, an opening angle from the most closed position of the arm <NUM>. Therefore, the arm angle θ2 is maximized when the arm <NUM> is opened most.

The bucket <NUM> is pivotably supported relative to the arm <NUM>. A bucket angle sensor S3 is attached to the bucket <NUM>. The bucket angle sensor S3 can detect a bucket angle θ3 that is the pivot angle of the bucket <NUM>. The bucket angle θ3 is, for example, an opening angle from the most closed position of the bucket <NUM>. Therefore, the bucket angle θ3 is maximized when the bucket <NUM> is opened most.

According to the embodiment of <FIG>, each of the boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3 is composed of a combination of an acceleration sensor and a gyroscope, but may also be composed of an acceleration sensor alone. Furthermore, the boom angle sensor S1 may also be a stroke sensor attached to the boom cylinder <NUM>, a rotary encoder, a potentiometer, an inertial measurement unit, or the like. The same is true for the arm angle sensor S2 and the bucket angle sensor S3.

A cabin <NUM> serving as a cab is provided and a power source such as an engine <NUM> is mounted on the upper swing structure <NUM>. Furthermore, a space recognition device <NUM>, an orientation detector <NUM>, a positioning device <NUM>, a machine body tilt sensor S4, a swing angular velocity sensor S5, etc., are attached to the upper swing structure <NUM>. An operating device <NUM>, a controller <NUM>, an information input device <NUM>, a display D1, a sound output device D2, etc., are provided in the cabin <NUM>. In this specification, for convenience, the side of the upper swing structure <NUM> on which the excavation attachment AT is attached is referred to as the front side, and the side of the upper swing structure <NUM> on which a counterweight is attached is referred to as the back side.

The space recognition device <NUM> is configured to recognize an object present in a three-dimensional space surrounding the shovel <NUM>. Furthermore, the space recognition device <NUM> is configured to calculate a distance from the space recognition device <NUM> or the shovel <NUM> to the recognized object. Examples of the space recognition device <NUM> include an ultrasonic sensor, a millimeter wave radar, a monocular camera, a stereo camera, a LIDAR, a distance image sensor, and an infrared sensor. According to the example illustrated in <FIG> and <FIG>, the space recognition device <NUM> includes a front sensor 70F attached to the front end of the upper surface of the cabin <NUM>, a back sensor 70B attached to the back end of the upper surface of the upper swing structure <NUM>, a left sensor <NUM> attached to the left end of the upper surface of the upper swing structure <NUM>, and a right sensor 70R attached to the right end of the upper surface of the upper swing structure <NUM>. An upper sensor that recognizes an object present in a space above the upper swing structure <NUM> may be attached to the shovel <NUM>.

The orientation detector <NUM> detects information on the relative relationship between the orientation of the upper swing structure <NUM> and the orientation of the lower traveling structure <NUM>. The orientation detector <NUM> may be constituted of, for example, a combination of a geomagnetic sensor attached to the lower traveling structure <NUM> and a geomagnetic sensor attached to the upper swing structure <NUM>. The orientation detector <NUM> may also be constituted of a combination of a GNSS receiver attached to the lower traveling structure <NUM> and a GNSS receiver attached to the upper swing structure <NUM>. The orientation detector <NUM> may also be a rotary encoder, a rotary position sensor, or the like. According to a configuration where the upper swing structure <NUM> is driven to swing by a swing motor generator, the orientation detector <NUM> may be constituted of a resolver. The orientation detector <NUM> may be attached to, for example, a center joint provided in relation to the swing mechanism <NUM> that achieves relative rotation between the lower traveling structure <NUM> and the upper swing structure <NUM>.

The orientation detector <NUM> may also be constituted of a camera attached to the upper swing structure <NUM>. In this case, the orientation detector <NUM> performs known image processing on an image captured by the camera attached to the upper swing structure <NUM> (an input image) to detect an image of the lower traveling structure <NUM> included in the input image. The orientation detector <NUM> may identify the longitudinal direction of the lower traveling structure <NUM> by detecting an image of the lower traveling structure <NUM> using a known image recognition technique and derive an angle formed between the direction of the longitudinal axis of the upper swing structure <NUM> and the longitudinal direction of the lower traveling structure <NUM>. The direction of the longitudinal axis of the upper swing structure <NUM> is derived from the attachment position of the camera. Because the crawlers 1C protrude from the upper swing structure <NUM>, the orientation detector <NUM> can identify the longitudinal direction of the lower traveling structure <NUM> by detecting an image of the crawlers 1C. In this case, the orientation detector <NUM> may be integrated into the controller <NUM>.

The information input device <NUM> is configured to enable the shovel operator to input information to the controller <NUM>. According to this embodiment, the information input device <NUM> is a switch panel installed near the display part of the display D1. The information input device <NUM>, however, may also be a touchscreen placed over the display part of the display D1 or a sound input device such as a microphone placed in the cabin <NUM>. Furthermore, the information input device <NUM> may also be a communications device. In this case, the operator can input information to the controller <NUM> via a communications terminal such as a smartphone.

The positioning device <NUM> is configured to measure a current position. According to this embodiment, the positioning device <NUM> is a GNSS receiver, and detects the position of the upper swing structure <NUM> to output a detection value to the controller <NUM>. The positioning device <NUM> may also be a GNSS compass. In this case, the positioning device <NUM> can detect the position and the orientation of the upper swing structure <NUM>.

The machine body tilt sensor S4 is configured to detect the tilt of the upper swing structure <NUM> relative to a predetermined plane. According to this embodiment, the machine body tilt sensor S4 is an acceleration sensor that detects the tilt angles of the upper swing structure <NUM> about its longitudinal axis and lateral axis relative to a horizontal plane. The longitudinal axis and the lateral axis of the upper swing structure <NUM>, for example, pass through a shovel central point that is a point on the swing axis of the shovel <NUM>, crossing each other at right angles.

The swing angular velocity sensor S5 is configured to detect the swing angular velocity of the upper swing structure <NUM>. According to this embodiment, the swing angular velocity sensor S5 is a gyroscope. The swing angular velocity sensor S5 may also be a resolver, a rotary encoder, or the like. The swing angular velocity sensor S5 may also detect swing speed. The swing speed may be calculated from swing angular velocity.

In the following, at least one of the boom angle sensor S1, the arm angle sensor S2, the bucket angle sensor S3, the machine body tilt sensor S4, and the swing angular velocity sensor S5 is also referred to as "pose detector. " The pose of the excavation attachment AT is detected based on the respective outputs of the boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3, for example.

The display D1 is a device that displays information. According to this embodiment, the display D1 is a liquid crystal display installed in the cabin <NUM>. The display D1 may also be the display of a communications terminal such as a smartphone.

The sound output device D2 is a device that outputs a sound. The sound output device D2 includes at least one of a device that outputs a sound to the operator in the cabin <NUM> and a device that outputs a sound to a worker outside the cabin <NUM>. The sound output device D2 may be a loudspeaker of a communications terminal.

The operating device <NUM> is a device that the operator uses to operate actuators. The operating device <NUM> is installed in the cabin <NUM> to be usable by the operator seated in the operator seat.

The controller <NUM> is a control device for controlling the shovel <NUM>. According to this embodiment, the controller <NUM> is constituted of a computer including a CPU, a RAM, an NVRAM, and a ROM. The controller <NUM> reads programs corresponding to functional elements such as an information obtaining part 30a and a control part 30b from the ROM, loads the programs into the RAM, and causes the CPU to execute processes corresponding to the functional elements. Thus, the functional elements are implemented by software. At least one of the functional elements, however, may be implemented by hardware or firmware. The functional elements are distinguished for the convenience of description, but are equally part of the controller <NUM> and do not have to be configured to be physically distinguishable.

Next, an example configuration of a hydraulic system installed in the shovel <NUM> is described with reference to <FIG> is a diagram illustrating an example configuration of the hydraulic system installed in the shovel <NUM>. In <FIG>, a mechanical power transmission system, a hydraulic oil line, a pilot line, and an electrical control system are indicated by a double line, a solid line, a dashed line, and a dotted line, respectively.

The hydraulic system of the shovel <NUM> mainly includes the engine <NUM>, a regulator <NUM>, a main pump <NUM>, a pilot pump <NUM>, a control valve unit <NUM>, the operating device <NUM>, a discharge pressure sensor <NUM>, an operating pressure sensor <NUM>, the controller <NUM>, and a solenoid valve <NUM>.

Referring to <FIG>, the hydraulic system is configured to be able to circulate hydraulic oil from the main pump <NUM> driven by the engine <NUM> to a hydraulic oil tank via a center bypass conduit <NUM> or a parallel conduit <NUM>.

The engine <NUM> is a drive source of the shovel <NUM>. According to this embodiment, the engine <NUM> is, for example, a diesel engine that operates to maintain a predetermined rotational speed. The output shaft of the engine <NUM> is connected to the respective input shafts of the main pump <NUM> and the pilot pump <NUM>.

The main pump <NUM> is configured to be able to supply hydraulic oil to the control valve unit <NUM> via a hydraulic oil line. According to this embodiment, the main pump <NUM> is a swash plate variable displacement hydraulic pump.

The regulator <NUM> is configured to be able to control the discharge quantity of the main pump <NUM>. According to this embodiment, the regulator <NUM> controls the discharge quantity of the main pump <NUM> by adjusting the swash plate tilt angle of the main pump <NUM> in response to a control command from the controller <NUM>.

The pilot pump <NUM> is configured to be able to supply hydraulic oil to hydraulic control apparatuses including the operating device <NUM> via a pilot line. According to this embodiment, the pilot pump <NUM> is a fixed displacement hydraulic pump. The pilot pump <NUM> may be omitted. In this case, the function carried by the pilot pump <NUM> may be implemented by the main pump <NUM>. That is, in addition to the function of supplying hydraulic oil to the control valve unit <NUM>, the main pump <NUM> may have the function of supplying hydraulic oil to the operating device <NUM>, etc., after reducing the pressure of the hydraulic oil with a throttle or the like.

The control valve unit <NUM> is a hydraulic controller that controls the hydraulic system in the shovel <NUM>. According to this embodiment, the control valve unit <NUM> includes directional control valves <NUM> through <NUM> and a control valve <NUM>. The directional control valve <NUM> includes a directional control valve <NUM> and a directional control valve 175R. The directional control valve <NUM> includes a directional control valve <NUM> and a directional control valve 176R. The control valve unit <NUM> is configured to be able to selectively supply hydraulic oil discharged by the main pump <NUM> to one or more hydraulic actuators through the directional control valves <NUM> through <NUM>. The directional control valves <NUM> through <NUM> control, for example, the flow rate of hydraulic oil flowing from the main pump <NUM> to hydraulic actuators and the flow rate of hydraulic oil flowing from hydraulic actuators to the hydraulic oil tank. The hydraulic actuators include the boom cylinder <NUM>, the arm cylinder <NUM>, the bucket cylinder <NUM>, the left travel hydraulic motor <NUM>, the right travel hydraulic motor 2MR, and the swing hydraulic motor 2A.

The operating device <NUM> is a device that the operator uses to operate actuators. The operating device <NUM> includes, for example, an operating lever and an operating pedal. The actuators include at least one of a hydraulic actuator and an electric actuator. According to this embodiment, the operating device <NUM> is configured to be able to supply hydraulic oil discharged by the pilot pump <NUM> to a pilot port of a corresponding directional control valve in the control valve unit <NUM> via a pilot line. The pressure of hydraulic oil supplied to each pilot port (pilot pressure) is a pressure commensurate with the direction of operation and the amount of operation of the operating device <NUM> corresponding to each hydraulic actuator. The operating device <NUM>, however, may be an electromagnetic pilot type instead of the above-described hydraulic pilot type. The directional valves in the control valve unit <NUM> may also be electromagnetic solenoid spool valves. Specifically, an electric operation system including an electric operating lever with an electric pilot circuit may be adopted instead of a hydraulic operation system with such a hydraulic pilot circuit. In this case, the amount of lever operation of the electric operating lever is input to the controller <NUM> as an electrical signal. Furthermore, a solenoid valve is placed between the pilot pump <NUM> and a pilot port of each control valve. The solenoid valve is configured to operate in response to an electrical signal from the controller <NUM>. According to this configuration, when a manual operation using the electric operating lever is performed, the controller <NUM> can move each control valve in the control valve unit <NUM> by increasing or decreasing a pilot pressure by controlling the solenoid valve with an electrical signal corresponding to the amount of lever operation. Each control valve may be constituted of a solenoid spool valve. In this case, the solenoid spool valve operates in response to an electrical signal from the controller <NUM> commensurate with the amount of lever operation of the electric operating lever.

The discharge pressure sensor <NUM> is configured to be able to detect the discharge pressure of the main pump <NUM>. According to this embodiment, the discharge pressure sensor <NUM> outputs a detected value to the controller <NUM>.

The operating pressure sensor <NUM> is configured to be able to detect the details of the operator's operation on the operating device <NUM>. According to this embodiment, the operating pressure sensor <NUM> detects the direction of operation and the amount of operation of the operating device <NUM> corresponding to each actuator in the form of pressure (operating pressure), and outputs a detected value to the controller <NUM>. The details of the operation of the operating device <NUM> may also be detected using a sensor other than an operating pressure sensor.

The main pump <NUM> includes a left main pump <NUM> and a right main pump 14R. The left main pump <NUM> circulates hydraulic oil to the hydraulic oil tank via a left center bypass conduit <NUM> or a left parallel conduit <NUM>. The right main pump 14R circulates hydraulic oil to the hydraulic oil tank via a right center bypass conduit 40R or a right parallel conduit 42R.

The left center bypass conduit <NUM> is a hydraulic oil line passing through the directional control valves <NUM>, <NUM>, <NUM> and <NUM> placed in the control valve unit <NUM>. The right center bypass conduit 40R is a hydraulic oil line passing through the directional control valves <NUM>, <NUM>, 175R and 176R placed in the control valve unit <NUM>.

The directional control valve <NUM> is a spool valve that switches the flow of hydraulic oil in order to supply hydraulic oil discharged by the left main pump <NUM> to the left travel hydraulic motor <NUM> and to discharge hydraulic oil discharged by the left travel hydraulic motor <NUM> to the hydraulic oil tank.

The directional control valve <NUM> is a spool valve that switches the flow of hydraulic oil in order to supply hydraulic oil discharged by the right main pump 14R to the right travel hydraulic motor 2MR and to discharge hydraulic oil discharged by the right travel hydraulic motor 2MR to the hydraulic oil tank.

The directional control valve <NUM> is a spool valve that switches the flow of hydraulic oil in order to supply hydraulic oil discharged by the left main pump <NUM> to the swing hydraulic motor 2A and to discharge hydraulic oil discharged by the swing hydraulic motor 2A to the hydraulic oil tank.

The directional control valve <NUM> is a spool valve that switches the flow of hydraulic oil in order to supply hydraulic oil discharged by the right main pump 14R to the bucket cylinder <NUM> and to discharge hydraulic oil in the bucket cylinder <NUM> to the hydraulic oil tank.

The directional control valve <NUM> is a spool valve that switches the flow of hydraulic oil in order to supply hydraulic oil discharged by the left main pump <NUM> to the boom cylinder <NUM>. The directional control valve 175R is a spool valve that switches the flow of hydraulic oil in order to supply hydraulic oil discharged by the right main pump 14R to the boom cylinder <NUM> and to discharge hydraulic oil in the boom cylinder <NUM> to the hydraulic oil tank.

The directional control valve <NUM> is a spool valve that switches the flow of hydraulic oil in order to supply hydraulic oil discharged by the left main pump <NUM> to the arm cylinder <NUM> and to discharge hydraulic oil in the arm cylinder <NUM> to the hydraulic oil tank.

The directional control valve 176R is a spool valve that switches the flow of hydraulic oil in order to supply hydraulic oil discharged by the right main pump 14R to the arm cylinder <NUM> and to discharge hydraulic oil in the arm cylinder <NUM> to the hydraulic oil tank.

The left parallel conduit <NUM> is a hydraulic oil line that runs parallel to the left center bypass conduit <NUM>. The left parallel conduit <NUM> is configured to be able to supply hydraulic oil to a control valve further downstream when the flow of hydraulic oil through the left center bypass conduit <NUM> is restricted or blocked by any of the directional control valves <NUM>, <NUM> and <NUM>. The right parallel conduit 42R is a hydraulic oil line that runs parallel to the right center bypass conduit 40R. The right parallel conduit 42R is configured to be able to supply hydraulic oil to a control valve further downstream when the flow of hydraulic oil through the right center bypass conduit 40R is restricted or blocked by any of the directional control valves <NUM>, <NUM> and 175R.

The control valve <NUM> is configured to have a variable opening area. According to this embodiment, the control valve <NUM> is a spool valve placed in the left parallel conduit <NUM>, and is configured to be able to adjust the flow area of the left parallel conduit <NUM>. Specifically, the control valve <NUM> is positioned downstream of a branch point BP1 in the left parallel conduit <NUM>, in order that the flow rate of hydraulic oil flowing into the arm cylinder <NUM> through the directional control valve <NUM> is adjusted by the control valve <NUM>. The branch point BP1 is a point at which a conduit CD1 connecting the left parallel conduit <NUM> and the directional control valve <NUM> branches from the left parallel conduit <NUM>. The control valve <NUM> may be provided upstream of the branch point BP1 and downstream of a branch point BP2 in the left parallel conduit <NUM>. In this case, the control valve <NUM> can control the flow rate of hydraulic oil flowing into the boom cylinder <NUM> through the directional control valve <NUM>. The branch point BP2 is a point at which a conduit CD2 connecting the left parallel conduit <NUM> and the directional control valve <NUM> branches from the left parallel conduit <NUM>.

Furthermore, the control valve <NUM> is positioned upstream of a junction JP1 in a conduit CD3 connecting the directional control valve 176R and the bottom-side oil chamber of the arm cylinder <NUM>, in order to prevent the flow of hydraulic oil flowing from the right main pump 14R into the bottom-side oil chamber of the arm cylinder <NUM> through the directional control valve 176R from being restricted by the control valve <NUM>. The junction JP1 is a point at which hydraulic oil flowing from the right main pump 14R into the bottom-side oil chamber of the arm cylinder <NUM> through the directional control valve 176R and hydraulic oil flowing from the left main pump <NUM> into the bottom-side oil chamber of the arm cylinder <NUM> through the directional control valve <NUM> meet.

The solenoid valve <NUM> is configured to be able to cause the control valve <NUM> to operate. According to this embodiment, the solenoid valve <NUM> is an electromagnetic proportional valve that operates in response to a control command (for example, a current command) from the controller <NUM>, and is placed in a conduit CD4 that is a pilot line connecting the control valve <NUM> and the pilot pump <NUM>. The solenoid valve <NUM> is configured to be able to adjust a control pressure acting on the pilot port of the control valve <NUM> to multiple levels using hydraulic oil discharged by the pilot pump <NUM>. The solenoid valve <NUM> may be configured to adjust a control pressure acting on the pilot port of the control valve <NUM> in a stepless manner.

According to this embodiment, the control valve <NUM> is a spool valve of an electromagnetic pilot type configured to reduce its opening area as a control pressure generated by the solenoid valve <NUM> increases. The control valve <NUM>, however, may be a spool valve of a hydraulic pilot type or a spool valve of an electromagnetic solenoid type. In the case of a spool valve of an electromagnetic solenoid type, the solenoid valve <NUM> is omitted.

The regulator <NUM> includes a left regulator <NUM> and a right regulator 13R. The left regulator <NUM> controls the discharge quantity of the left main pump <NUM> by adjusting the swash plate tilt angle of the left main pump <NUM> in accordance with the discharge pressure of the left main pump <NUM>. Specifically, for example, the left regulator <NUM> reduces the discharge quantity of the left main pump <NUM> by adjusting its swash plate tilt angle as the discharge pressure of the left main pump <NUM> increases. The same is the case with the right regulator 13R. This is for preventing the absorbed power (for example, the absorbed horsepower) of the main pump <NUM> expressed as the product of discharge pressure and discharge quantity from exceeding the output power (for example, the output horsepower) of the engine <NUM>.

The operating device <NUM> includes a left operating lever <NUM>, a right operating lever 26R, and travel levers 26D. The travel levers 26D include a left travel lever 26DL and a right travel lever 26DR.

The left operating lever <NUM> is used for swing operation and for operating the arm <NUM>. The left operating lever <NUM> is operated forward or backward to cause a control pressure commensurate with the amount of lever operation to act on a pilot port of the directional control valve <NUM>, using hydraulic oil discharged by the pilot pump <NUM>. Furthermore, the left operating lever <NUM> is operated rightward or leftward to cause a control pressure commensurate with the amount of lever operation to act on a pilot port of the directional control valve <NUM>, using hydraulic oil discharged by the pilot pump <NUM>.

Specifically, the left operating lever <NUM> is operated in an arm closing direction to introduce hydraulic oil to the right pilot port of the directional control valve <NUM> and introduce hydraulic oil to the left pilot port of the directional control valve 176R. Furthermore, the left operating lever <NUM> is operated in an arm opening direction to introduce hydraulic oil to the left pilot port of the directional control valve <NUM> and introduce hydraulic oil to the right pilot port of the directional control valve 176R. Furthermore, the left operating lever <NUM> is operated in a counterclockwise swing direction to introduce hydraulic oil to the left pilot port of the directional control valve <NUM>, and is operated in a clockwise swing direction to introduce hydraulic oil to the right pilot port of the directional control valve <NUM>.

The right operating lever 26R is used to operate the boom <NUM> and to operate the bucket <NUM>. The right operating lever 26R is operated forward or backward to cause a control pressure commensurate with the amount of lever operation to act on a pilot port of the directional control valve <NUM>, using hydraulic oil discharged by the pilot pump <NUM>. Furthermore, the right operating lever 26R is operated rightward or leftward to cause a control pressure commensurate with the amount of lever operation to act on a pilot port of the directional control valve <NUM>, using hydraulic oil discharged by the pilot pump <NUM>.

Specifically, the right operating lever 26R is operated in a boom lowering direction to introduce hydraulic oil to the left pilot port of the directional control valve 175R. Furthermore, the right operating lever 26R is operated in a boom raising direction to introduce hydraulic oil to the right pilot port of the directional control valve <NUM> and to introduce hydraulic oil to the left pilot port of the directional control valve 175R. Furthermore, the right operating lever 26R is operated in a bucket closing direction to introduce hydraulic oil to the right pilot port of the directional control valve <NUM>, and is operated in a bucket opening direction to introduce hydraulic oil to the left pilot port of the directional control valve <NUM>.

The travel levers 26D are used to operate the crawlers 1C. Specifically, the left travel lever 26DL is used to operate the left crawler 1CL. The left travel lever 26DL may be configured to operate together with a left travel pedal. The left travel lever 26DL is operated forward or backward to cause a control pressure commensurate with the amount of lever operation to act on a pilot port of the directional control valve <NUM>, using hydraulic oil discharged by the pilot pump <NUM>. The right travel lever 26DR is used to operate the right crawler 1CR. The right travel lever 26DR may be configured to operate together with a right travel pedal. The right travel lever 26DR is operated forward or backward to cause a control pressure commensurate with the amount of lever operation to act on a pilot port of the directional control valve <NUM>, using hydraulic oil discharged by the pilot pump <NUM>.

The discharge pressure sensor <NUM> includes a discharge pressure sensor <NUM> and a discharge pressure sensor 28R. The discharge pressure sensor <NUM> detects the discharge pressure of the left main pump <NUM>, and outputs a detected value to the controller <NUM>. The same is the case with the discharge pressure sensor 28R.

The operating pressure sensor <NUM> includes operating pressure sensors 29LA, 29LB, 29RA, 29RB, 29DL and 29DR. The operating pressure sensor 29LA detects the details of the operator's forward or backward operation of the left operating lever <NUM> in the form of pressure, and outputs a detected value to the controller <NUM>. Examples of the details of operation include the direction of lever operation and the amount of lever operation (the angle of lever operation).

Likewise, the operating pressure sensor 29LB detects the details of the operator's rightward or leftward operation of the left operating lever <NUM> in the form of pressure, and outputs a detected value to the controller <NUM>. The operating pressure sensor 29RA detects the details of the operator's forward or backward operation of the right operating lever 26R in the form of pressure, and outputs a detected value to the controller <NUM>. The operating pressure sensor 29RB detects the details of the operator's rightward or leftward operation of the right operating lever 26R in the form of pressure, and outputs a detected value to the controller <NUM>. The operating pressure sensor 29DL detects the details of the operator's forward or backward operation of the left travel lever 26DL in the form of pressure, and outputs a detected value to the controller <NUM>. The operating pressure sensor 29DR detects the details of the operator's forward or backward operation of the right travel lever 26DR in the form of pressure, and outputs a detected value to the controller <NUM>.

The controller <NUM> receives the output of the operating pressure sensor <NUM>, and outputs a control command to the regulator <NUM> to change the discharge quantity of the main pump <NUM> on an as-needed basis. Furthermore, the controller <NUM> receives the output of a control pressure sensor <NUM> provided upstream of a throttle <NUM>, and outputs a control command to the regulator <NUM> to change the discharge quantity of the main pump <NUM> on an as-needed basis. The throttle <NUM> includes a left throttle <NUM> and a right throttle 18R. The control pressure sensor <NUM> includes a left control pressure sensor <NUM> and a right control pressure sensor 19R.

The left throttle <NUM> is placed between the most downstream control valve <NUM> and the hydraulic oil tank in the left center bypass conduit <NUM>. Therefore, the flow of hydraulic oil discharged by the left main pump <NUM> is restricted by the left throttle <NUM>. The left throttle <NUM> generates a control pressure for controlling the left regulator <NUM>. The left control pressure sensor <NUM> is a sensor for detecting this control pressure, and outputs a detected value to the controller <NUM>. The controller <NUM> controls the discharge quantity of the left main pump <NUM> by adjusting the swash plate tilt angle of the left main pump <NUM> in accordance with this control pressure. The controller <NUM> decreases the discharge quantity of the left main pump <NUM> as this control pressure increases, and increases the discharge quantity of the left main pump <NUM> as this control pressure decreases. The discharge quantity of the right main pump 14R is controlled in the same manner.

Specifically, when the hydraulic system is in a standby state where none of the hydraulic actuators is operated in the shovel <NUM> as illustrated in <FIG>, hydraulic oil discharged by the left main pump <NUM> arrives at the left throttle <NUM> through the left center bypass conduit <NUM>. The flow of hydraulic oil discharged by the left main pump <NUM> increases the control pressure generated upstream of the left throttle <NUM>. As a result, the controller <NUM> decreases the discharge quantity of the left main pump <NUM> to a minimum allowable discharge quantity to reduce pressure loss (pumping loss) during the passage of the hydraulic oil discharged by the left main pump <NUM> through the left center bypass conduit <NUM>. In contrast, when any of the hydraulic actuators is operated, hydraulic oil discharged by the left main pump <NUM> flows into the operated hydraulic actuator via a directional control valve corresponding to the operated hydraulic actuator. The flow of hydraulic oil discharged by the left main pump <NUM> that arrives at the left throttle <NUM> is reduced in amount or lost, so that the control pressure generated upstream of the left throttle <NUM> is reduced. As a result, the controller <NUM> increases the discharge quantity of the left main pump <NUM> to cause sufficient hydraulic oil to flow into the operated hydraulic actuator to ensure driving of the operated hydraulic actuator. The controller <NUM> controls the discharge quantity of the right main pump 14R in the same manner.

According to the configuration as described above, the hydraulic system of <FIG> can reduce unnecessary energy consumption in the main pump <NUM> in the standby state. The unnecessary energy consumption includes pumping loss that hydraulic oil discharged by the main pump <NUM> causes in the center bypass conduit <NUM>. Furthermore, in the case of actuating a hydraulic actuator, the hydraulic system of <FIG> can ensure that necessary and sufficient hydraulic oil is supplied from the main pump <NUM> to the hydraulic actuator to be actuated.

Next, the information obtaining part 30a and the control part 30b, which are functional elements of the controller <NUM>, are described. The information obtaining part 30a is configured to obtain information on the shovel <NUM>. According to this embodiment, the information obtaining part 30a is configured to obtain information on the work details of the shovel <NUM> from at least one of the boom angle sensor S1, the arm angle sensor S2, the bucket angle sensor S3, the machine body tilt sensor S4, the swing angular velocity sensor S5, a cylinder pressure sensor, a swing pressure sensor, a travel pressure sensor, a boom cylinder stroke sensor, an arm cylinder stroke sensor, a bucket cylinder stroke sensor, the discharge pressure sensor <NUM>, the operating pressure sensor <NUM>, the space recognition device <NUM>, the orientation detector <NUM>, the information input device <NUM>, the positioning device <NUM>, and a communications device. The cylinder pressure sensor includes at least one of, for example, a boom rod pressure sensor, a boom bottom pressure sensor, an arm rod pressure sensor, an arm bottom pressure sensor, a bucket rod pressure sensor, and a bucket bottom pressure sensor.

The information on the work details of the shovel <NUM> includes, for example, information on work that the shovel <NUM> is performing. Examples of work that the shovel <NUM> is performing include swing and press excavation, aerial arm closing and swinging, aerial arm opening and swinging, aerial boom raising and swinging, aerial boom lowering and swinging, aerial bucket closing and swinging, and aerial bucket opening and swinging. The aerial arm closing and swinging is the motion of swinging the upper swing structure <NUM> while closing the arm <NUM> in the air. The same applies to the aerial arm opening and swinging, the aerial boom raising and swinging, the aerial boom lowering and swinging, the aerial bucket closing and swinging, the aerial bucket opening and swinging, etc..

The information obtaining part 30a, for example, as the information on the work details of the shovel <NUM>, obtains at least one of the boom angle, the arm angle, the bucket angle, a machine body tilt angle, swing angular velocity, a boom rod pressure, a boom bottom pressure, an arm rod pressure, an arm bottom pressure, a bucket rod pressure, a bucket bottom pressure, a swing pressure, a travel pressure, a boom stroke amount, an arm stroke amount, a bucket stroke amount, the discharge pressure of the main pump <NUM>, the operating pressure of the operating device <NUM>, information on an object present in a three-dimensional space surrounding the shovel <NUM>, information on the relative relationship between the orientation of the upper swing structure <NUM> and the orientation of the lower traveling structure <NUM>, information input to the controller <NUM>, and information on a current position.

The control part 30b is configured to be able to control the motion of the shovel <NUM> based on the information on the work details of the shovel <NUM>. According to this embodiment, the control part 30b is configured to be able to adjust the opening area of the control valve <NUM> to a value suitable for the swing and press excavation during the swing and press excavation. Furthermore, the control part 30b is configured to be able to adjust the opening area of the control valve <NUM> to a value suitable for the aerial arm closing and swinging during the aerial arm closing and swinging.

Here, control performed by the control part 30b when a complex operation including an arm closing operation and a clockwise swing operation has been performed is described in detail with reference to <FIG> and <FIG>. <FIG> illustrates a relationship between a clockwise swing pilot pressure Pi that acts on the right pilot port of the directional control valve <NUM> and an opening area Sa of the control valve <NUM>. <FIG> is a flowchart of an example of the process of adjusting the opening area Sa of the control valve <NUM> by the controller <NUM> (hereinafter "adjustment process"). The controller <NUM> repeatedly executes this adjustment process at predetermined control intervals.

First, the controller <NUM> determines whether an arm closing operation is being performed (step ST1). According to this embodiment, the control part 30b of the controller <NUM> determines whether an arm closing operation is being performed based on the output of the operating pressure sensor 29LA serving as the information obtaining part 30a. In the case where an electric operating lever is employed, the controller <NUM> determines whether an arm closing operation is being performed based on an electrical signal output by the left operating lever <NUM>.

In response to determining that an arm closing operation is being performed (YES at step ST1), the controller <NUM> determines whether a swing operation is being performed (step ST2). According to this embodiment, the control part 30b of the controller <NUM> determines whether a swing operation is being performed based on the output of the operating pressure sensor 29LB serving as the information obtaining part 30a. In the case where an electric operating lever is employed, the controller <NUM> determines whether a swing operation is being performed based on an electrical signal output by the left operating lever <NUM>.

In response to determining that a swing operation is being performed (YES at step ST2), the controller <NUM> determines whether a discharge pressure Pp of the left main pump <NUM> is more than or equal to a predetermined threshold TH (step ST3). According to this embodiment, in response to determining that a swing operation is being performed, namely, in response to determining that a complex operation including an arm closing operation and a swing operation is being performed, the control part 30b of the controller <NUM> executes step ST3. Specifically, the control part 30b determines whether the discharge pressure Pp of the left main pump <NUM> is more than or equal to the threshold TH based on the output of the discharge pressure sensor <NUM> serving as the information obtaining part 30a. The threshold TH is prestored in the NVRAM.

While the controller <NUM> performs the determination of step ST2 after performing the determination of step ST1 according to this embodiment, the order of step ST1 and step ST2 is random. That is, the controller <NUM> may perform the determination of step ST1 after performing the determination of step ST2, or may perform the determination of step ST1 and the determination of step ST2 simultaneously. Furthermore, the determination of step ST1 may be omitted.

In response to determining that the discharge pressure Pp of the left main pump <NUM> is more than or equal to the predetermined threshold TH (YES at step ST3), the controller <NUM> adopts a first pattern PT1 as the transition pattern of the opening area Sa of the control valve <NUM> (step ST4). According to this embodiment, in response to determining that the discharge pressure Pp of the left main pump <NUM> is more than or equal to the predetermined threshold TH, the control part 30b of the controller <NUM> determines that the swing and press excavation is being performed. Then, the control part 30b, for example, outputs a control command to the solenoid valve <NUM> to reduce the opening area of the control valve <NUM> to a value suitable for the swing and press excavation (a value determined by the first pattern PT1).

The transition pattern of the opening area Sa of the control valve <NUM> is a pattern that represents the correspondence between the clockwise swing pilot pressure Pi and the opening area Sa of the control valve <NUM>. According to this embodiment, the first pattern PT1 is a pattern indicated by a solid line in <FIG>, and is stored in the NVRAM in such a manner as to be able to be referred to. According to the first pattern PT1, the opening area Sa is a reference value Sa3 when the clockwise swing pilot pressure Pi is less than a value Pi1, decreases to a first set value Sa1 as the clockwise swing pilot pressure Pi increases when the clockwise swing pilot pressure Pi is more than or equal to the value Pi1 and less than a value Pi3, and is the first set value Sa1 when the clockwise swing pilot pressure Pi is more than or equal to the value Pi3. The reference value Sa3 corresponds to the opening area of the control valve <NUM> when no swing operation is performed.

The control part 30b of the controller <NUM> determines a current clockwise swing pilot pressure Pic from the output of the operating presser sensor 29LB, and derives an opening area Sac1 corresponding to the current clockwise swing pilot pressure Pic, referring to the first pattern PT1. Then, the control part 30b outputs a control command corresponding to the derived opening area Sac1 to the solenoid valve <NUM> to adjust the opening area of the control valve <NUM> to the opening area Sac1. Control commands corresponding to the values of the opening area Sa are typically prestored in the NVRAM or the like.

In response to determining that the discharge pressure Pp of the left main pump <NUM> is less than the predetermined threshold TH (NO at step ST3), the controller <NUM> adopts a second pattern PT2 as the transition pattern of the opening area Sa of the control valve <NUM> (step ST5). According to this embodiment, in response to determining that the discharge pressure Pp of the left main pump <NUM> is less than the predetermined threshold TH, the control part 30b of the controller <NUM> determines that the aerial arm closing and swinging is being performed. Then, the control part 30b, for example, outputs a control command to the solenoid valve <NUM> to reduce the opening area of the control valve <NUM> to a value suitable for the aerial arm closing and swinging (a value determined by the second pattern PT2). The value suitable for the aerial arm closing and swinging is typically greater than the value suitable for the swing and press excavation.

According to this embodiment, the second pattern PT2 is a pattern indicated by a one-dot chain line in <FIG>, and is prestored in the NVRAM in such a manner as to be able to be referred to. According to the second pattern PT2, the opening area Sa is the reference value Sa3 when the clockwise swing pilot pressure Pi is less than a value Pi2, decreases to a second set value Sa2 as the clockwise swing pilot pressure Pi increases when the clockwise swing pilot pressure Pi is more than or equal to the value Pi2 and less than the value Pi3, and is the second set value Sa2 when the clockwise swing pilot pressure Pi is more than or equal to the value Pi3. The control part 30b of the controller <NUM> determines the current clockwise swing pilot pressure Pic from the output of the operating presser sensor 29LB, and derives an opening area Sac2 corresponding to the current clockwise swing pilot pressure Pic, referring to the second pattern PT2. Then, the control part 30b outputs a control command corresponding to the derived opening area Sac2 to the solenoid valve <NUM> to adjust the opening area of the control valve <NUM> to the opening area Sac2.

In response to determining that no arm closing operation is being performed (NO at step ST1) or in response to determining that no swing operation is being performed (NO at step ST2), that is, in response to determining that no complex operation including an arm closing operation and a swing operation is being performed, the controller <NUM> adopts a reference pattern PT3 as the transition pattern of the opening area Sa of the control valve <NUM> (step ST6). According to this embodiment, in response to determining that arm closing is being performed alone, the control part 30b of the controller <NUM> outputs a control command to the solenoid valve <NUM> to set the opening area of the control valve <NUM> to a value suitable for arm closing (a value determined by the reference pattern PT3).

According to this embodiment, the reference pattern PT3 is a pattern indicated by a dashed line in <FIG>, and is prestored in the NVRAM in such a manner as to be able to be referred to. According to the reference pattern PT3, the opening area Sa is the reference value Sa3 irrespective of the magnitude of the clockwise swing pilot pressure Pi. The control part 30b of the controller <NUM> outputs a control command corresponding to the reference value Sa3 to the solenoid valve <NUM> to adjust the opening area of the control valve <NUM> to the reference value Sa3.

Thus, the controller <NUM> can control the opening area Sa of the control valve <NUM> according to information on work details so that the shovel <NUM> can make movements suitable for the work details. Specifically, in response to determining that the swing and press excavation is being performed, the controller <NUM> can adjust the opening area Sa of the control valve <NUM> to a value suitable for the swing and press excavation. Furthermore, in response to determining that the aerial arm closing and swinging is being performed, the controller <NUM> can adjust the opening area Sa of the control valve <NUM> to a value suitable for the aerial arm closing and swinging.

As described above, the shovel <NUM> according to an embodiment of the present invention includes the lower traveling structure <NUM>, the upper swing structure <NUM> swingably mounted on the lower traveling structure <NUM>, the left main pump <NUM> mounted on the upper swing structure <NUM> as a first hydraulic pump, the excavation attachment AT attached to the upper swing structure <NUM> as an attachment, the swing hydraulic motor 2A as a first actuator, the arm cylinder <NUM> as a second actuator, the directional control valve <NUM> as a first directional control valve corresponding to the swing hydraulic motor 2A, the directional control valve <NUM> as a second directional control valve corresponding to the arm cylinder <NUM>, the left center bypass conduit <NUM> as a first conduit connecting the left main pump <NUM> and the directional control valve <NUM>, the left parallel conduit <NUM> as a second conduit connecting the left center bypass conduit <NUM> and the directional control valve <NUM>, the control valve <NUM> installed in the left parallel conduit <NUM>, and the controller <NUM> as a control device to control the opening area Sa of the control valve <NUM> according to information on work details.

According to this configuration, the shovel <NUM> can stabilize the shovel motion when a complex operation including a swing operation is performed. For example, the shovel <NUM> can stabilize the motion of the shovel <NUM> when the swing and press excavation or the aerial arm closing and swinging through a complex operation including an arm closing operation and a swing operation has been performed. This is because the controller <NUM> can control the opening area Sa of the control valve <NUM> to a value suitable for the swing and press excavation during the swing and press excavation and because the controller <NUM> can control the opening area Sa of the control valve <NUM> to a value suitable for the aerial arm closing and swinging during the aerial arm closing and swinging.

In other words, this is because the controller <NUM> can prevent the opening area Sa of the control valve <NUM> from being adjusted to a value suitable for the swing and press excavation during the aerial arm closing and swinging. When the opening area Sa of the control valve <NUM> is adjusted to a value suitable for the swing and press excavation during the aerial arm closing and swinging, the flow rate of hydraulic oil toward the bottom-side oil chamber of the arm cylinder <NUM> may be insufficient. This is because the flow rate of hydraulic oil toward the bottom-side oil chamber of the arm cylinder <NUM> is restricted by the control valve <NUM>, although the volume of the bottom-side oil chamber of the arm cylinder <NUM> tends to increase because the arm <NUM> is falling in a closing direction because of its own weight. According to the above-described configuration, the shovel <NUM> can prevent the occurrence of such insufficiency.

The second actuator is an actuator to move the attachment, and may be the boom cylinder <NUM>. In this case, the second directional control valve may be the directional control valve <NUM>.

The left parallel conduit <NUM> as the second conduit is configured to connect a portion of the left center bypass conduit <NUM> as the first conduit upstream of the directional control valve <NUM> as the first directional control valve to the directional control valve <NUM> as the second directional control valve. That is, the left parallel conduit <NUM> as the second conduit is configured to allow hydraulic oil discharged by the left main pump <NUM> to avoid passing through and bypass the directional control valve <NUM> as the first directional control valve.

Desirably, the controller <NUM> is configured to determine the work details based on the discharge pressure Pp of the left main pump <NUM>. For example, when a complex operation including an arm closing operation and a swing operation is being performed, the controller <NUM> determines that the swing and press excavation is being performed if the discharge pressure Pp is the predetermined threshold TH, and determines that the aerial arm closing and swinging is being performed if the discharge pressure Pp is less than the predetermined threshold TH. According to this configuration, the controller <NUM> can easily determine the work details of the shovel. The controller <NUM>, however, may determine the work details based on at least one of the pose detector that detects the pose of the attachment, an image captured by a camera serving as the front sensor 70F, and the output value of the cylinder pressure sensor.

The controller <NUM> may set the opening area Sa of the control valve <NUM> to the first set value Sa1 smaller than the predetermined reference value Sa3 if a load related to a swing actuator or an attachment actuator is more than or equal to a predetermined threshold during a complex operation including a swing operation and an operation of the attachment. The load related to a swing actuator or an attachment actuator may be detected or calculated as a load on the main pump <NUM> or may be detected or calculated as a load on the engine <NUM>. For example, when the discharge pressure of the left main pump <NUM> is more than or equal to the predetermined threshold TH during a complex operation including a swing operation and an arm closing operation, so that it is determined that the swing and press excavation is being performed, the controller <NUM> may set the opening area Sa when the clockwise swing pilot pressure Pi is a value Pid to the first set value Sa1 as illustrated in <FIG>.

According to this configuration, the controller <NUM> can increase the flow rate and the pressure of hydraulic oil toward the swing hydraulic motor 2A by setting the opening area Sa of the control valve <NUM> to the first set value Sa1 to restrict the flow of hydraulic oil toward the bottom-side oil chamber of the arm cylinder <NUM>. Therefore, the controller <NUM> can prevent a large part of hydraulic oil discharged by the left main pump <NUM> from flowing into the bottom-side oil chamber of the arm cylinder <NUM> to excessively reduce the flow rate of hydraulic oil toward the swing hydraulic motor 2A during the swing and press excavation. As a result, the operator of the shovel <NUM> can smoothly perform the swing and press excavation.

The controller <NUM> may set the opening area Sa of the control valve <NUM> to the second set value Sa2, which is smaller than the reference value Sa3 and greater than the first set value Sa1, if the load related to the swing actuator or the attachment actuator is less than the predetermined threshold during the complex operation including the swing operation and the operation of the attachment. For example, when the discharge pressure of the left main pump <NUM> is less than the predetermined threshold TH during a complex operation including a swing operation and an arm closing operation, so that it is determined that the aerial arm closing and swinging is being performed, the controller <NUM> may set the opening area Sa when the clockwise swing pilot pressure Pi is the value Pid to the second set value Sa2 as illustrated in <FIG>.

According to this configuration, the controller <NUM> can prevent the flow of hydraulic oil toward the bottom-side oil chamber of the arm cylinder <NUM> from being excessively restricted during the aerial arm closing and swinging. Therefore, the controller <NUM> can prevent the flow rate of hydraulic oil toward the bottom-side oil chamber of the arm cylinder <NUM> from being excessively reduced during the aerial arm closing and swinging. As a result, the operator of the shovel <NUM> can smoothly perform the aerial arm closing and swinging.

The reference value Sa3 is desirably the opening area of the control valve <NUM> when no swing operation is being performed. Accordingly, the second set value Sa2 is a value greater than the opening area during the swing and press excavation but smaller than the opening area when no swing operation is being performed, namely, during the aerial arm closing in which an arm closing operation is being performed alone.

Therefore, the controller <NUM> can perform the aerial arm closing and swinging with the flow of hydraulic oil toward the bottom-side oil chamber of the arm cylinder <NUM> being restricted compared with the case of the aerial arm closing but being less restricted than in the case of the swing and press excavation. As a result, the controller <NUM> can cause an appropriate amount of hydraulic oil to flow into each of the swing hydraulic motor 2A and the arm cylinder <NUM> at an appropriate pressure during the aerial arm closing and swinging and can improve the operability during the aerial arm closing and swinging.

The attachment actuator may also be the boom cylinder <NUM> or the bucket cylinder <NUM>. In this case, the swing and press excavation may be excavation achieved by moving the boom <NUM> while pressing the side of the bucket <NUM> against an object of excavation through a complex operation including a swing operation and a boom raising operation or a boom lowering operation. The controller <NUM> may be configured to be able to distinguish between this swing and press excavation and the aerial boom raising and swinging or the aerial boom lowering and swinging. The swing and press excavation may also be excavation achieved by moving the bucket <NUM> while pressing the side of the bucket <NUM> against an object of excavation through a complex operation including a swing operation and a bucket closing operation or a bucket opening operation. The controller <NUM> may be configured to be able to distinguish between this swing and press excavation and the aerial bucket closing and swinging or the aerial bucket opening and swinging. The swing and press excavation may also be excavation achieved by opening the arm <NUM> while pressing the side of the bucket <NUM> against an object of excavation through a complex operation including a swing operation and an arm opening operation. The controller <NUM> may be configured to be able to distinguish between this swing and press excavation and the aerial arm opening and swinging.

The shovel <NUM> desirably includes the pilot pump <NUM> and the solenoid valve <NUM>. The solenoid valve <NUM> is placed in the conduit CD4 connecting the control valve <NUM> and the pilot pump <NUM>. According to this simple configuration, the shovel <NUM> can stabilize the motion of the shovel <NUM> when a complex operation including a swing operation is performed.

The shovel <NUM> desirably includes the right main pump 14R as a second hydraulic pump separate from the left main pump <NUM>, the directional control valve 176R as a third directional control valve separate from the directional control valve <NUM>, corresponding to the arm cylinder <NUM>, and the conduit CD3 connecting the arm cylinder <NUM> and the directional control valve 176R. The conduit CD3 incudes the junction JP1 where hydraulic oil discharged by the left main pump <NUM> meets hydraulic oil discharged by the right main pump 14R. The control valve <NUM> is positioned upstream of the junction JP1.

According to this configuration, the shovel <NUM> can appropriately supply hydraulic oil discharged by the left main pump <NUM> to the swing hydraulic motor 2A without unnecessarily restricting the flow of hydraulic oil discharged by the right main pump 14R.

A preferred embodiment of the present invention is described above. The present invention, however, is not limited to the above-described embodiment. Various variations and substitutions may be applied to the above-described embodiment without departing from the scope of the present invention as defined by the appended claims.

Furthermore, separately described features may be combined to the extent that no technical contradiction is caused.

For example, the controller <NUM> may restrict the size of a variation in a control command to the solenoid valve <NUM>, in order to prevent the motion of the shovel <NUM> from being destabilized by a sudden change in the opening area Sa of the control valve <NUM> when the transition pattern of the opening area Sa is switched between the first pattern PT1, the second pattern PT2, and the reference pattern PT3.

Furthermore, the hydraulic system installed in the shovel <NUM> may also be configured as illustrated in <FIG> illustrates another example configuration of the hydraulic system installed in the shovel <NUM>. In <FIG>, the same as in <FIG>, a mechanical power transmission system, a hydraulic oil line, a pilot line, and an electrical control system are indicated by a double line, a solid line, a dashed line, and a dotted line, respectively.

The hydraulic system illustrated in <FIG> is different from the hydraulic system illustrated in <FIG> mainly in including a proportional valve <NUM>, a conduit <NUM>, and a bleed valve <NUM> from, but otherwise equal to the hydraulic system illustrated in <FIG>. Therefore, in the following, the description of a common portion is omitted, and differences are described in detail.

The hydraulic system illustrated in <FIG> includes the conduit <NUM> in place of the center bypass conduit <NUM> and the parallel conduit <NUM> in the hydraulic system illustrated in <FIG>.

The conduit <NUM> includes a left conduit <NUM> and a right conduit 43R. The left conduit <NUM> is a hydraulic oil line that connects the directional control valves <NUM>, <NUM>, <NUM>, and <NUM> placed in the control valve unit <NUM> in parallel between the left main pump <NUM> and the hydraulic oil tank. The right conduit 43R is a hydraulic oil line that connects the directional control valves <NUM>, <NUM>, 175R, and 176R placed in the control valve unit <NUM> in parallel between the right main pump 14R and the hydraulic oil tank.

The bleed valve <NUM> controls the flow rate of a portion of hydraulic oil discharged by the main pump <NUM> that flows to the hydraulic oil tank without going through any hydraulic actuator (hereinafter, "bleed flow rate"). The bleed valve <NUM> may be installed in the control valve unit <NUM>.

Specifically, the bleed valve <NUM> is a spool valve that controls the bleed flow rate with respect to hydraulic oil discharged by the main pump <NUM>. According to the example illustrated in <FIG>, the bleed valve <NUM> includes a left bleed valve <NUM> and a right bleed valve 178R. The left bleed valve <NUM> is a spool valve that controls the bleed flow rate with respect to hydraulic oil discharged by the left main pump <NUM>. The right bleed valve 178R is a spool valve that controls the bleed flow rate with respect to hydraulic oil discharged by the right main pump 14R.

The bleed valve <NUM> is, for example, configured to be movable between a first valve position of a minimum opening area (a degree of opening of <NUM> %) and a second valve position of a maximum opening area (a degree of opening of <NUM> %). According to the example illustrated in <FIG>, the bleed valve <NUM> is configured to be movable in a stepless manner between the first valve position and the second valve position.

The proportional valve <NUM> is configured to operate in response to a control command output by the controller <NUM>. According to the example illustrated in <FIG>, the proportional valve <NUM> is a solenoid valve that adjusts a secondary pressure introduced from the pilot pump <NUM> to the pilot port of the bleed valve <NUM> according to a current command output by the controller <NUM>. The proportional valve <NUM>, for example, operates to increase the secondary pressure introduced to the pilot port of the bleed valve <NUM> as the supplied current increases.

The controller <NUM> is configured to be able to output a current command to the proportional valve <NUM> to change the opening area of the bleed valve <NUM> on an as-needed basis.

Specifically, the proportional valve <NUM> is configured to be able to adjust the secondary pressure introduced from the pilot pump <NUM> to the pilot port of the bleed valve <NUM> according to a current command output by the controller <NUM>. According to the example illustrated in <FIG>, the proportional valve <NUM> includes a left proportional valve <NUM> and a right proportional valve 31R. The left proportional valve <NUM> can adjust the secondary pressure so that the left bleed valve <NUM> can stop at any position between the first valve position and the second valve position. The right proportional valve 31R can adjust the secondary pressure so that the right bleed valve 178R can stop at any position between the first valve position and the second valve position.

Next, negative control adopted in the hydraulic system illustrated in <FIG> is described. In the conduit <NUM>, the throttle <NUM> is placed between the bleed valve <NUM>, which is the most downstream spool valve, and the hydraulic oil tank. The flow of hydraulic oil arriving at the hydraulic tank through the bleed valve <NUM> is restricted by the throttle <NUM>. The throttle <NUM> generates a control pressure for controlling the regulator <NUM>, namely, a control pressure for controlling the discharge quantity of the main pump <NUM>. The control pressure sensor <NUM> is a sensor for detecting the control pressure, and outputs a detected value to the controller <NUM>.

According to the example illustrated in <FIG>, the throttle <NUM> is a fixed throttle whose opening area does not change, and includes the left throttle <NUM>, placed between the left bleed valve <NUM> and the hydraulic oil tank in the left conduit <NUM>, and the right throttle 18R, placed between the right bleed valve 178R and the hydraulic oil tank in the right conduit 43R. The control pressure sensor <NUM> includes the left control pressure sensor <NUM> that detects the control pressure generated by the left throttle <NUM> to control the left regulator <NUM> and the right control pressure sensor 19R that detects the control pressure generated by the right throttle 18R to control the right regulator 13R.

The controller <NUM> controls the discharge quantity (geometric displacement) of the main pump <NUM> by adjusting the swash plate tilt angle of the main pump <NUM> according to the control pressure. The relationship between the control pressure and the discharge quantity of the main pump <NUM> is referred to as "negative control characteristic. " The discharge quantity control based on the negative control characteristic, for example, may be achieved by using a reference table stored in the ROM or the like or may be achieved by performing predetermined calculations in real time. According to the example illustrated in <FIG>, the controller <NUM> refers to a reference table representing a predetermined negative control characteristic to decrease the discharge quantity of the main pump <NUM> as the control pressure increases and increase the discharge quantity of the main pump <NUM> as the control pressure decreases.

Specifically, when no operating device <NUM> is operated and no hydraulic actuators are in operation, namely, when the hydraulic system is in the standby state, as illustrated in <FIG>, hydraulic oil discharged by the left main pump <NUM> arrives at the left throttle <NUM> through the left bleed valve <NUM>. When the flow rate of the hydraulic oil arriving at the left throttle <NUM> is higher than or equal to a predetermined flow rate, the control pressure generated upstream of the left throttle <NUM> reaches a predetermined pressure. When the control pressure reaches a predetermined pressure, the controller <NUM> reduces the discharge quantity of the left main pump <NUM> to a predetermined minimum allowable discharge quantity to reduce pressure loss (pumping loss) during the passage of the discharged hydraulic oil through the left conduit <NUM>. This predetermined minimum allowable discharge quantity in the standby state is referred to as "standby flow rate. " The controller <NUM> controls the discharge quantity of the right main pump 14R in the same manner.

In contrast, when any of the hydraulic actuators is operated, hydraulic oil discharged by the left main pump <NUM> flows into the operated hydraulic actuator via a directional control valve corresponding to the operated hydraulic actuator. The controller <NUM> outputs a control command to the left proportional valve <NUM> to reduce the opening area of the left bleed valve <NUM> according to the amount of movement of the directional control valve corresponding to the operated hydraulic actuator. The amount of movement of the directional control valve corresponds to a control pressure acting on a pilot port of the directional control valve. When two or more directional control valves are simultaneously moved, the controller <NUM> reduces the opening area of the left bleed valve <NUM> according to the total amount of movement of the directional control valves. The controller <NUM> is configured to typically reduce the opening area of the left bleed valve <NUM> as the total amount of movement of directional control valves increases. In this case, the flow rate of hydraulic oil arriving at the left throttle <NUM> through the left bleed valve <NUM> is reduced, so that the control pressure generated upstream of the left throttle <NUM> decreases. As a result, the controller <NUM> increases the discharge quantity of the left main pump <NUM> to supply sufficient hydraulic oil to the operated hydraulic actuator to ensure driving of the operated hydraulic actuator. The controller <NUM> controls the discharge quantity of the right main pump 14R in the same manner. The flow rate of hydraulic oil flowing into a hydraulic actuator is referred to as "actuator flow rate. " The flow rate of hydraulic oil discharged by the left main pump <NUM> corresponds to the sum of the actuator flow rate with respect to the left conduit <NUM> and the bleed flow rate with respect to the left conduit <NUM>. The same applies to the flow rate of hydraulic oil discharged by the right main pump 14R.

According to the above-described configuration, in the case of actuating a hydraulic actuator, the hydraulic system illustrated in <FIG> can ensure that necessary and sufficient hydraulic oil is supplied from the main pump <NUM> to the hydraulic actuator to be actuated. Furthermore, the hydraulic system illustrated in <FIG> can reduce unnecessary consumption of hydraulic energy in the standby state. This is because the bleed flow rate can be reduced to the standby flow rate. The same is the case with the hydraulic system illustrated in <FIG>.

According to the example illustrated in <FIG>, the control valve <NUM> is placed in a conduit CD5 connecting the left conduit <NUM> and the directional control valve <NUM>.

According to this configuration, when the aerial arm closing and swinging or the swing and press excavation is performed, the controller <NUM> outputs a control command to the left proportional valve <NUM> to reduce the opening area of the left bleed valve <NUM>. At this point, the opening area of the left bleed valve <NUM> has a size corresponding to the amount of movement of the directional control valve <NUM> corresponding to the swing hydraulic motor 2A and the amount of movement of the directional control valve <NUM> corresponding to the arm cylinder <NUM>. In response to determining that the swing and press excavation is being performed, the controller <NUM> outputs a control command to the solenoid valve <NUM> to change the opening area of the control valve <NUM> to a value suitable for the swing and press excavation. Therefore, in response to determining that the swing and press excavation is being performed, the controller <NUM> can reduce the flow rate of hydraulic oil flowing into the directional control valve <NUM> compared with the case of determining that the aerial arm closing and swinging is being performed. Conversely, in response to determining that the aerial arm closing and swinging is being performed, the controller <NUM> outputs a control command to the solenoid valve <NUM> to change the opening area of the control valve <NUM> to a value suitable for the aerial arm closing and swinging. Therefore, in response to determining that the aerial arm closing and swinging is being performed, the controller <NUM> can increase the flow rate of hydraulic oil flowing into the directional control valve <NUM> compared with the case of determining that the swing and press excavation is being performed.

According to this configuration, the hydraulic system illustrated in <FIG> can achieve the same effect as produced by the hydraulic system illustrated in <FIG>. Specifically, the hydraulic system illustrated in <FIG> can stabilize the motion of the shovel <NUM> when the swing and press excavation or the aerial arm closing and swinging is performed.

Furthermore, instead of a hydraulic operation system, an electric operation system may be installed in the shovel <NUM>. <FIG> illustrates an example configuration of an electric operation system. Specifically, the electric operation system of <FIG> is an example of a swing operation system, and is constituted mainly of the pilot pressure-operated control valve unit <NUM>, the left operating lever <NUM> serving as an electric operating lever, the controller <NUM>, a solenoid valve <NUM> for counterclockwise swing operation, and a solenoid valve <NUM> for clockwise swing operation. The electric operation system of <FIG> may also be likewise applied to a boom operation system, an arm operation system, a bucket operation system, a travel operation system, etc..

As illustrated in <FIG>, the pilot pressure-operated control valve unit <NUM> includes the directional control valve <NUM> associated with the left travel hydraulic motor <NUM>, the directional control valve <NUM> associated with the right travel hydraulic motor 2MR, the directional control valve <NUM> associated with the swing hydraulic motor 2A, the directional control valve <NUM> associated with the bucket cylinder <NUM>, the directional control valve <NUM> associated with the boom cylinder <NUM>, the directional control valve <NUM> associated with the arm cylinder <NUM>, etc. The solenoid valve <NUM> is configured to be able to adjust the flow area of a conduit connecting the pilot pump <NUM> and the left pilot port of the directional control valve <NUM>. The solenoid valve <NUM> is configured to be able to adjust the flow area of a conduit connecting the pilot pump <NUM> and the right pilot port of the directional control valve <NUM>.

When a manual operation is performed, the controller <NUM> generates a counterclockwise swing operation signal (electrical signal) or a clockwise swing operation signal (electrical signal) in accordance with an operation signal (electrical signal) output by an operation signal generating part of the left operating lever <NUM>. The operation signal output by the operation signal generating part of the left operating lever <NUM> is an electrical signal that changes according to the direction of operation and the amount of operation the left operating lever <NUM>.

Specifically, when the left operating lever <NUM> is operated in the counterclockwise swing direction, the controller <NUM> outputs a counterclockwise swing operation signal (electrical signal) commensurate with the amount of lever operation to the solenoid valve <NUM>. The solenoid valve <NUM> adjusts the flow area in accordance with the counterclockwise swing operation signal (electrical signal) to control a pilot pressure serving as a counterclockwise swing operation signal (pressure signal) that acts on the left pilot port of the directional control valve <NUM>. Likewise, when the left operating lever <NUM> is operated in the clockwise swing direction, the controller <NUM> outputs a clockwise swing operation signal (electrical signal) commensurate with the amount of lever operation to the solenoid valve <NUM>. The solenoid valve <NUM> adjusts the flow area in accordance with the clockwise swing operation signal (electrical signal) to control a pilot pressure serving as a clockwise swing operation signal (pressure signal) that acts on the right pilot port of the directional control valve <NUM>.

In the case of executing an autonomous control function, the controller <NUM>, for example, generates the counterclockwise swing operation signal (electrical signal) or the clockwise swing operation signal (electrical signal) according to an autonomous control signal (electrical signal) instead of responding to the operation signal (electrical signal) output by the operation signal generating part of the left operating lever <NUM>. The autonomous control function is a function for causing the shovel <NUM> to autonomously operate, and includes, for example, a function to cause a hydraulic actuator to autonomously operate independent of the details of the operator's operation of the operating device <NUM>. The autonomous control signal may be an electrical signal generated by the controller <NUM> or an electrical signal generated by an external control device other than the controller <NUM>.

Here, control executed by the control part 30b when a complex operation including an arm closing operation and a clockwise swing operation is performed using the electric operation system is described in detail with reference to <FIG> is a graph illustrating a relationship between a clockwise swing operation signal (electrical signal) Si output to the solenoid valve <NUM> and the opening area Sa of the control valve <NUM>, and corresponds to <FIG>.

The same as in the case of the hydraulic operation system, in response to determining that the swing and press excavation is being performed, the control part 30b adopts the first pattern PT1 as the transition pattern of the opening area Sa of the control valve <NUM>. Then, the control part 30b outputs a control command to the solenoid valve <NUM> to reduce the opening area of the control valve <NUM> to a value suitable for the swing and press excavation (a value determined by the first pattern PT1 of <FIG>).

The transition pattern of the opening area Sa of the control valve <NUM> is a pattern that represents the correspondence between the clockwise swing operation signal (electrical signal) Si and the opening area Sa of the control valve <NUM>. The first pattern PT1 is a pattern indicated by a solid line in <FIG>, and is stored in the NVRAM in such a manner as to be able to be referred to. According to the first pattern PT1, the opening area Sa is the reference value Sa3 when the clockwise swing operation signal (electrical signal) Si is less than a value Si1, decreases to the first set value Sa1 as the clockwise swing operation signal (electrical signal) Si increases when the clockwise swing operation signal (electrical signal) Si is more than or equal to the value Si1 and less than a value Si3, and is the first set value Sa1 when the clockwise swing operation signal (electrical signal) Si is more than or equal to the value Si3. The reference value Sa3 corresponds to the opening area of the control valve <NUM> when no swing operation is being performed.

The control part 30b determines a current clockwise swing operation signal (electrical signal) Sic from the output of the left operating lever <NUM>, and derives the opening area Sac1 corresponding to the current clockwise swing operation signal (electrical signal) Sic, referring to the first pattern PT1. Then, the control part 30b outputs a control command corresponding to the derived opening area Sac1 to the solenoid valve <NUM> to adjust the opening area of the control valve <NUM> to the opening area Sac1. Control commands corresponding to the values of the opening area Sa are typically prestored in the NVRAM or the like.

In response to determining that the aerial arm closing and swinging is being performed, the control part 30b adopts the second pattern PT2 of <FIG> as the transition pattern of the opening area Sa of the control valve <NUM>. Then, the control part 30b, for example, outputs a control command to the solenoid valve <NUM> to reduce the opening area of the control valve <NUM> to a value suitable for the aerial arm closing and swinging (a value determined by the second pattern PT2). The value suitable for the aerial arm closing and swinging is typically greater than the value suitable for the swing and press excavation.

The second pattern PT2 is a pattern indicated by a one-dot chain line in <FIG>, and is prestored in the NVRAM in such a manner as to be able to be referred to. According to the second pattern PT2, the opening area Sa is the reference value Sa3 when the clockwise swing operation signal (electrical signal) Si is less than a value Si2, decreases to the second set value Sa2 as the clockwise swing operation signal (electrical signal) Si increases when the clockwise swing operation signal (electrical signal) Si is more than or equal to the value Si2 and less than the value Si3, and is the second set value Sa2 when the clockwise swing operation signal (electrical signal) Si is more than or equal to the value Si3.

The control part 30b determines the current clockwise swing operation signal (electrical signal) Sic from the output of the left operating lever <NUM>, and derives the opening area Sac2 corresponding to the current clockwise swing operation signal (electrical signal) Sic, referring to the second pattern PT2. Then, the control part 30b outputs a control command corresponding to the derived opening area Sac2 to the solenoid valve <NUM> to adjust the opening area of the control valve <NUM> to the opening area Sac2.

In response to determining that arm closing is being performed alone, the control part 30b outputs a control command to the solenoid valve <NUM> to set the opening area of the control valve <NUM> to a value suitable for arm closing (a value determined by the reference pattern PT3 of <FIG>).

The reference pattern PT3 is a pattern indicated by a dashed line in <FIG>, and is prestored in the NVRAM in such a manner as to be able to be referred to. According to the reference pattern PT3, the opening area Sa is the reference value Sa3 irrespective of the magnitude of the clockwise swing operation signal (electrical signal) Si. The control part 30b outputs a control command corresponding to the reference value Sa3 to the solenoid valve <NUM> to adjust the opening area of the control valve <NUM> to the reference value Sa3.

Thus, in the case of using the electric operation system as well, the controller <NUM> can control the opening area Sa of the control valve <NUM> according to information on work details so that the shovel <NUM> can make movements suitable for the work details, the same as in the case of using the hydraulic operation system. Specifically, in response to determining that the swing and press excavation is being performed, the controller <NUM> can adjust the opening area Sa of the control valve <NUM> to a value suitable for the swing and press excavation. Furthermore, in response to determining that the aerial arm closing and swinging is being performed, the controller <NUM> can adjust the opening area Sa of the control valve <NUM> to a value suitable for the aerial arm closing and swinging.

Furthermore, the hydraulic system installed in the shovel <NUM> may also be configured as illustrated in <FIG> illustrates yet another example configuration of the hydraulic system installed in the shovel <NUM>. In <FIG>, the same as in <FIG>, a mechanical power transmission system, a hydraulic oil line, a pilot line, and an electrical control system are indicated by a double line, a solid line, a dashed line, and a dotted line, respectively.

The hydraulic system illustrated in <FIG> is different from the hydraulic system illustrated in <FIG> mainly in that an electric operation system is installed instead of a hydraulic operation system from, but otherwise equal to the hydraulic system illustrated in <FIG>. Therefore, in the following, a description of a common portion is omitted, and differences are described in detail.

According to the hydraulic system illustrated in <FIG>, each of the directional control valves <NUM> through <NUM> is constituted of a solenoid spool valve. Furthermore, each of the directional control valves <NUM> through <NUM> is configured to operate in response to a control signal from the controller <NUM>. Therefore, according to the hydraulic system illustrated in <FIG>, the solenoid valve <NUM>, the control valve <NUM>, and the conduit CD4 in the hydraulic system illustrated in <FIG> are omitted. This is because the controller <NUM> can cause the directional control valve <NUM> to operate independent of the direction of operation and the amount of operation of the left operating lever <NUM>.

Specifically, the controller <NUM> can determine the details of the work of the shovel <NUM> including arm closing based on an operation signal output by the operation signal generating part of the left operating lever <NUM>. Examples of the determination of the details of work including arm closing include a determination as to whether the swing and press excavation is being performed, whether the aerial arm closing and swinging is being performed, whether the arm closing is being performed alone, etc. The controller <NUM> can adjust the flow rate of hydraulic oil flowing into the directional control valve <NUM> the same as in the case of moving the control valve <NUM>, by moving the directional control valve <NUM> irrespective of the amount of operation of the left operating lever <NUM> according to the determination result. According to the example illustrated in <FIG>, the controller <NUM> is configured such that the amount of adjustment by the directional control valve <NUM> is equal to the amount of adjustment by the control valve <NUM> in the hydraulic system illustrated in <FIG>.

According to this configuration, the hydraulic system illustrated in <FIG> can achieve the same effect as the effect produced by the hydraulic system illustrated in <FIG>.

Next, another example configuration of the shovel <NUM> according to this embodiment is described with reference to <FIG>. According to the example illustrated in <FIG>, the shovel <NUM> includes a first hydraulic pump PM1 provided on the upper swing structure, a first actuator ACT1, a second actuator ACT2, a first directional control valve DV1 corresponding to the first actuator ACT1, a second directional control valve DV2 corresponding to the second actuator ACT2, a first conduit HP1 connecting the first hydraulic pump PM1 and the first directional control valve DV1, a second conduit HP2 connecting the first conduit HP1 and the second directional control valve DV2, a control valve VL installed in the second conduit HP2, and a control device CTR that controls the opening area of the control valve VL according to information on work details.

The first hydraulic pump PM1 is, for example, the left main pump <NUM> or the right main pump 14R. The first actuator ACT1 is, for example, one of the swing hydraulic motor 2A, the travel hydraulic motors <NUM>, the boom cylinder <NUM>, the arm cylinder <NUM>, and the bucket cylinder <NUM>, and the second actuator ACT2 is another one of the swing hydraulic motor 2A, the travel hydraulic motors <NUM>, the boom cylinder <NUM>, the arm cylinder <NUM>, and the bucket cylinder <NUM>.

According to this configuration, the shovel <NUM> can stabilize its motion when a complex operation is performed. This is because, for example, when a complex operation including an operation of the first actuator ACT1 and an operation of the second actuator ACT2 has been performed, the shovel <NUM> can adjust the flow rate of hydraulic oil flowing into the first actuator ACT1 by adjusting the flow rate of hydraulic oil flowing into the second actuator ACT2. Specifically, for example, in the case where the first actuator ACT1 is the swing hydraulic motor 2A and the second actuator ACT2 is the arm cylinder <NUM>, the shovel <NUM> can stabilize the motion of the shovel <NUM> when a complex operation including a swing operation, such as the swing and press excavation or the aerial arm closing and swinging, is performed. This is because it is possible to adjust the flow rate of hydraulic flowing into the swing hydraulic motor 2A by adjusting the flow rate of hydraulic oil flowing into the arm cylinder <NUM>.

The present application is based upon and claims priority to <CIT>.

Claim 1:
A shovel (<NUM>) comprising:
a lower traveling structure (<NUM>);
an upper swing structure (<NUM>) swingably mounted on the lower traveling structure (<NUM>);
a first hydraulic pump (PM1) provided on the upper swing structure (<NUM>);
an attachment (AT) attached to the upper swing structure (<NUM>);
a first actuator (ACT1);
a second actuator (ACT2);
a first directional control valve (DV1) corresponding to the first actuator (ACT1);
a second directional control valve (DV2) corresponding to the second actuator (ACT2);
a first conduit (HP1) connecting the first hydraulic pump (PM1) and the first directional control valve (DV1);
a second conduit (HP2) connecting the first conduit (HP1) and the second directional control valve (DV2);
a control valve (VL) installed in the second conduit (HP2); characterized in that the shovel further comprises
a control device (CTR, <NUM>) configured to adopt a transition pattern from among a plurality of transition patterns (PT1, PT2, PT3) that represent correspondence between an amount of operation for the first actuator (ACT1) and an opening area of the control valve (VL) according to information on work details and to control the opening area of the control valve (VL) according to the adopted transition pattern,
wherein the information on work details comprises information about a complex operation including an operation of the first actuator (ACT1) and an operation of the second actuator (ACT2).