JP6878073B2 - Excavator - Google Patents

Description

The present invention relates to an excavator with an attachment driven by a hydraulic cylinder.

Excavators equipped with attachments driven by hydraulic cylinders are known (see Patent Document 1). This excavator automatically controls the expansion and contraction of the boom cylinder so as to prevent the cutting edge of the bucket from entering the target excavation terrain. Hydraulic oil is supplied to the boom cylinder through a spool-type control valve. When automatically controlling the expansion and contraction of the boom cylinder, the spool of the control valve is controlled by the pilot pressure generated independently of the operation by the operator. This pilot pressure is controlled so that the target spool movement amount can be achieved based on the detection value of the spool stroke sensor that detects the spool movement amount. This is to perform automatic control of the boom cylinder with high accuracy.

Japanese Patent No. 5990642

However, since the excavator of Patent Document 1 uses a spool stroke sensor, the structure around the control valve becomes complicated.

Therefore, it is desirable to provide an excavator that can control the hydraulic cylinder with high accuracy without using a spool stroke sensor.

The excavator according to the embodiment of the present invention includes a lower traveling body, an upper swivel body mounted on the lower traveling body, an attachment attached to the upper swivel body, a hydraulic cylinder for operating the attachment, and the upper part. A hydraulic pump mounted on the swivel body, a spool-type control valve that controls the flow rate of hydraulic oil flowing from the hydraulic pump to the hydraulic cylinder, and a control device that controls the displacement of the spool-type control valve are provided. The control device feedback-controls the displacement of the spool-type control valve based on the estimated flow rate of the hydraulic oil passing through the spool-type control valve and the estimated flow rate of the hydraulic oil flowing into the hydraulic cylinder. To do.

By the above means, it is possible to provide an excavator capable of controlling a hydraulic cylinder with high accuracy without using a spool stroke sensor.

It is a side view of the excavator which concerns on embodiment of this invention. It is a figure which shows the structural example of the drive system of the excavator of FIG. It is a figure which shows the configuration example of the operation device which attached the adjustment mechanism. It is a control flow diagram which shows an example of attachment automatic control processing. It is a side view of the excavator which shows the state of the excavation attachment which executes the excavation operation according to the preset operation pattern. It is a figure which shows the relationship of the parameter about the movement of the excavation attachment. It is a control flow diagram which shows another example of the attachment automatic control processing.

FIG. 1 is a side view showing an excavator (excavator) as a construction machine to which the present invention is applied. An upper swivel body 3 is mounted on the lower traveling body 1 of the excavator via a swivel mechanism 2. A boom 4 is attached to the upper swing body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 as an end attachment is attached to the tip of the arm 5. The boom 4, arm 5, and bucket 6 as working elements constitute an excavation attachment, which is an example of the attachment, and are hydraulically driven by the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9, respectively.

A boom angle sensor S1 is attached to the boom 4, an arm angle sensor S2 is attached to the arm 5, and a bucket angle sensor S3 is attached to the bucket 6. Further, the body tilt sensor S4 and the swing angular velocity sensor S5 are attached to the upper swing body 3.

The boom angle sensor S1 is a sensor that acquires a boom angle, which is a rotation angle of the boom 4 with respect to the upper swing body 3. The boom angle sensor S1 detects, for example, a rotation angle sensor that detects the rotation angle of the boom 4 around the boom foot pin, a cylinder stroke sensor that detects the stroke amount (boom stroke amount) of the boom cylinder 7, and an inclination angle of the boom 4. Includes tilt (acceleration) sensors and the like. It may be a combination of an acceleration sensor and a gyro sensor. The same applies to the arm angle sensor that detects the arm angle that is the rotation angle of the arm 5 with respect to the boom 4 and the bucket angle sensor that detects the bucket angle that is the rotation angle of the bucket 6 with respect to the arm 5.

The airframe tilt sensor S4 detects the tilt (airframe tilt angle) of the upper swivel body 3 with respect to the horizontal plane. In this embodiment, the body tilt sensor S4 is an acceleration sensor that detects the tilt angles around the front-rear axis and the left-right axis of the upper swing body 3. The front-rear axis and the left-right axis of the upper swivel body 3 pass, for example, the excavator center point which is one point on the excavator swivel axis orthogonal to each other.

The turning angular velocity sensor S5 detects the turning angular velocity of the upper swing body 3. In this embodiment, it is a gyro sensor. It may be a resolver, a rotary encoder, or the like.

A boom rod pressure sensor S6a, a boom bottom pressure sensor S6b, and a boom cylinder stroke sensor S7 are attached to the boom cylinder 7. An arm rod pressure sensor S6c, an arm bottom pressure sensor S6d, and an arm cylinder stroke sensor S8 are attached to the arm cylinder 8. A bucket rod pressure sensor S6e, a bucket bottom pressure sensor S6f, and a bucket cylinder stroke sensor S9 are attached to the bucket cylinder 9.

The boom rod pressure sensor S6a detects the pressure in the rod side oil chamber of the boom cylinder 7 (hereinafter referred to as “boom rod pressure”), and the boom bottom pressure sensor S6b detects the pressure in the bottom side oil chamber of the boom cylinder 7 (hereinafter referred to as “boom rod pressure”). , "Boom bottom pressure") is detected. The arm rod pressure sensor S6c detects the pressure in the rod side oil chamber of the arm cylinder 8 (hereinafter referred to as “arm rod pressure”), and the arm bottom pressure sensor S6d detects the pressure in the bottom side oil chamber of the arm cylinder 8 (hereinafter referred to as “arm rod pressure”). , "Arm bottom pressure") is detected. The bucket rod pressure sensor S6e detects the pressure in the rod side oil chamber of the bucket cylinder 9 (hereinafter referred to as "bucket rod pressure"), and the bucket bottom pressure sensor S6f detects the pressure in the bottom side oil chamber of the bucket cylinder 9 (hereinafter referred to as "bucket rod pressure"). , "Bucket bottom pressure") is detected.

The upper swing body 3 is provided with a cabin 10 as an cab and is equipped with a power source such as an engine 11.

FIG. 2 is a block diagram showing a configuration example of the drive system of the excavator of FIG. 1, and the mechanical power transmission line, hydraulic oil line, pilot line, and electric control line are shown by double lines, thick solid lines, broken lines, and dotted lines, respectively. Shown.

The drive system of the excavator mainly includes an engine 11, a regulator 13, a main pump 14, a pilot pump 15, a control valve 17, an operating device 26, a discharge pressure sensor 28, an operating pressure sensor 29, a controller 30, an information acquisition device 40, and the like. Including.

The engine 11 is a drive source for the excavator. In this embodiment, the engine 11 is, for example, a diesel engine as an internal combustion engine that operates so as to maintain a predetermined rotation speed. Further, the output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15.

The main pump 14 is a device for supplying hydraulic oil to the control valve 17 via a hydraulic oil line, and is, for example, a swash plate type variable displacement hydraulic pump.

The regulator 13 is a device for controlling the discharge amount of the main pump 14. In this embodiment, the regulator 13 controls the discharge amount of the main pump 14 by, for example, adjusting the swash plate tilt angle of the main pump 14 according to the discharge pressure of the main pump 14, the command current from the controller 30, and the like. To do.

The pilot pump 15 is a device that supplies hydraulic oil to various hydraulic control devices including an operating device 26 via a pilot line, and is, for example, a fixed-capacity hydraulic pump.

The control valve 17 is a flood control device that controls a flood control system in an excavator. Specifically, the control valve 17 includes a plurality of spool-type control valves that control the flow of hydraulic oil discharged by the main pump 14. For example, a boom control valve 17A, an arm control valve 17B, a bucket control valve 17C, a left traveling motor control valve 17D, a right traveling motor control valve 17E, and a swivel control valve 17F are included. Then, the control valves 17 selectively supply the hydraulic oil discharged by the main pump 14 to one or a plurality of hydraulic actuators through these control valves. These control valves are the flow rate of hydraulic oil flowing from the main pump 14 to the hydraulic oil tank through the center bypass pipeline, the flow rate of hydraulic oil flowing from the main pump 14 to the hydraulic actuator, and the operation flowing from the hydraulic actuator to the hydraulic oil tank. Control the flow rate of oil. The hydraulic actuator includes a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left traveling hydraulic motor 1L, a right traveling hydraulic motor 1R, and a swivel hydraulic motor 2A.

The operating device 26 is a device used by the operator to operate the hydraulic actuator. In this embodiment, the operating device 26 is installed in the cabin 10 and supplies the hydraulic oil discharged by the pilot pump 15 to the pilot ports of the control valves corresponding to the respective hydraulic actuators via the pilot line. The pressure of the hydraulic oil supplied to each of the pilot ports (hereinafter referred to as "pilot pressure") is a pressure corresponding to the operation direction and operation amount of the lever or pedal of the operation device 26 corresponding to each of the hydraulic actuators. is there.

The discharge pressure sensor 28 is a pressure sensor that detects the pressure of the hydraulic oil discharged by the main pump 14. In this embodiment, the discharge pressure sensor 28 outputs the detected value to the controller 30.

The operating pressure sensor 29 is a pressure sensor for detecting the operation content of the operating device 26. In this embodiment, the operating pressure sensor 29 detects, for example, the operating direction and operating amount of the lever or pedal of the operating device 26 corresponding to each of the hydraulic actuators in the form of pressure, and the detected value is transmitted to the controller 30. Output. The operation content of the operation device 26 may be detected by using a sensor other than the pressure sensor.

The information acquisition device 40 detects information about the excavator. In this embodiment, the information acquisition device 40 includes a boom angle sensor S1, an arm angle sensor S2, a bucket angle sensor S3, a body tilt sensor S4, a turning angle speed sensor S5, a boom rod pressure sensor S6a, a boom bottom pressure sensor S6b, and an arm rod. Pressure sensor S6c, arm bottom pressure sensor S6d, bucket rod pressure sensor S6e, bucket bottom pressure sensor S6f, boom cylinder stroke sensor S7, arm cylinder stroke sensor S8, bucket cylinder stroke sensor S9, discharge pressure sensor 28, and operating pressure sensor. Includes at least one of 29. The information acquisition device 40, for example, provides information on the excavation attachment, such as boom angle, arm angle, bucket angle, body tilt angle, turning angular velocity, boom rod pressure, boom bottom pressure, arm rod pressure, arm bottom pressure, bucket rod pressure, At least one of the bucket bottom pressure, the boom stroke amount, the arm stroke amount, the bucket stroke amount, the discharge pressure of the main pump 14, and the operating pressure of the operating device 26 is acquired.

The controller 30 is a control device for controlling the excavator. In this embodiment, the controller 30 is composed of, for example, a computer including a CPU, RAM, NVRAM, ROM, and the like. Further, the controller 30 reads the program corresponding to the attachment control unit 31 from the ROM, loads it into the RAM, and causes the CPU to execute the corresponding processing.

The attachment control unit 31 is a functional element that controls the movement of the attachment. Basically, the attachment moves in response to an operation on each of the plurality of operating devices 26. On the other hand, the attachment control unit 31 can move the attachment regardless of whether or not the operation device 26 is operated.

For example, the excavation attachment basically moves according to the operation of the boom operating lever, the arm operating lever, and the bucket operating lever as the operating device 26. On the other hand, the attachment control unit 31 can move the excavation attachment according to a preset operation pattern regardless of whether or not the boom operation lever, the arm operation lever, and the bucket operation lever are operated, for example.

The operation pattern is represented by, for example, a combination of time-series data (target values) of the boom cylinder inflow amount, the arm cylinder inflow amount, and the bucket cylinder inflow amount. The combination of time series data (target value) is set, for example, in 1-second increments. The boom cylinder inflow rate is the flow rate of hydraulic oil flowing into the boom cylinder 7 through the boom control valve 17A. The arm cylinder inflow rate is the flow rate of hydraulic oil flowing into the arm cylinder 8 through the arm control valve 17B. The bucket cylinder inflow rate is the flow rate of hydraulic oil flowing into the bucket cylinder 9 through the bucket control valve 17C. In this case, the posture of the excavation attachment at a certain point in the future is determined by the transition of the boom cylinder inflow amount, the arm cylinder inflow amount, and the bucket cylinder inflow amount up to that point. The operation pattern may be represented by a combination of time-series data (target values) of the boom stroke amount, the arm stroke amount, and the bucket stroke amount. In this case, the boom cylinder inflow amount, the arm cylinder inflow amount, and the bucket cylinder inflow amount are calculated from the boom stroke amount, the arm stroke amount, and the bucket stroke amount. Alternatively, the operation pattern may be represented by a combination of time-series data (target values) of the boom cylinder expansion / contraction speed, the arm cylinder expansion / contraction speed, and the bucket cylinder expansion / contraction speed. In this case, the boom cylinder inflow amount, the arm cylinder inflow amount, and the bucket cylinder inflow amount are calculated from the boom cylinder expansion / contraction speed, the arm cylinder expansion / contraction speed, and the bucket cylinder expansion / contraction speed.

In this embodiment, the boom operating lever and the bucket operating lever are described as separate and independent operating levers, but they may be physically the same operating lever and differ only in the tilting direction. The same applies to the relationship between the arm operating lever and the turning operating lever.

Next, with reference to FIG. 3, an example of a control mechanism that realizes automatic control of the excavation attachment will be described. FIG. 3 is a diagram showing a configuration example of an arm operating lever 26A as an operating device 26 to which the control mechanism 50 is attached. The following description is similarly applied to other operating levers to which the control mechanism 50 is attached. For example, the same applies to a boom operating lever to which a control mechanism 50 for moving the boom control valve 17A is attached, a bucket operating lever to which a control mechanism 50 for moving the bucket control valve 17C is attached, and the like. Liver.

The control mechanism 50 is a mechanism for adjusting the spool position of the arm control valve 17B, and mainly includes a solenoid valve 51, a solenoid valve 52L, a solenoid valve 52R, and the like.

The solenoid valve 51 is an electromagnetic proportional pressure reducing valve arranged in a pipeline connecting the pilot pump 15 and the arm operating lever 26A, and its opening area is increased or decreased according to the control current from the controller 30.

The solenoid valve 52L is an electromagnetic switching valve arranged in the pipeline C1 connecting the arm operating lever 26A and the left pilot port 17L of the arm control valve 17B, and switches the valve position in response to a command from the controller 30. .. Pipeline C1 includes lineage C11 and line C12. The solenoid valve 52L has a first valve position and a second valve position. The first valve position communicates the pipeline C11 and the pipeline C12, and blocks the communication between the pipeline C3 and the pipeline C12. The second valve position cuts off the communication between the pipeline C11 and the pipeline C12, and allows the pipeline C3 and the pipeline C12 to communicate with each other. The pipeline C11 connects the arm operating lever 26A and the solenoid valve 52L. The pipeline C12 connects the solenoid valve 52L and the left pilot port 17L of the arm control valve 17B. The pipeline C3 connects the solenoid valve 51 and the solenoid valve 52L.

The solenoid valve 52R is an electromagnetic switching valve arranged in the pipeline C2 connecting the arm operating lever 26A and the right pilot port 17R of the arm control valve 17B, and switches the valve position in response to a command from the controller 30. .. Pipeline C2 includes lineage C21 and line C22. The solenoid valve 52R has a first valve position and a second valve position. The first valve position communicates the pipeline C21 and the pipeline C22, and blocks the communication between the pipeline C4 and the pipeline C22. The second valve position cuts off the communication between the pipeline C21 and the pipeline C22, and allows the pipeline C4 and the pipeline C22 to communicate with each other. The pipeline C21 connects the arm operating lever 26A and the solenoid valve 52R. The pipeline C22 connects the solenoid valve 52R and the right pilot port 17R of the arm control valve 17B. The pipeline C4 connects the solenoid valve 51 and the solenoid valve 52R.

When the arm operating lever 26A is tilted in the closing direction, the pressure of the hydraulic oil in the pipeline C1 is increased, and when tilted in the opening direction, the pressure of the hydraulic oil in the pipeline C2 is increased. The arm closing pilot pressure, which is the pressure of the hydraulic oil in the pipeline C1, is detected by the arm closing pilot pressure sensor 29L, which is an example of the operating pressure sensor 29. The arm opening pilot pressure, which is the pressure of the hydraulic oil in the pipeline C2, is detected by the arm opening pilot pressure sensor 29R, which is an example of the operating pressure sensor 29. When the arm closing pilot pressure increases, the arm control valve 17B as a spool valve moves to the right to communicate the main pump 14 with the oil chamber on the bottom side of the arm cylinder 8 to extend the arm cylinder 8. When the arm opening pilot pressure increases, the arm control valve 17B moves to the left to communicate the main pump 14 with the rod-side oil chamber of the arm cylinder 8 to contract the arm cylinder 8.

When the arm cylinder 8 is automatically extended, the attachment control unit 31 outputs a spool control command (current command) to the solenoid valve 51 and an open command to the solenoid valve 52L. The solenoid valve 51 that receives the spool control command operates so as to realize an opening area corresponding to the spool control command. The solenoid valve 52L that receives the open command switches to the second valve position, and the hydraulic oil discharged by the pilot pump 15 flows into the pipeline C12.

Similarly, when the arm cylinder 8 is automatically contracted, the attachment control unit 31 outputs a spool control command to the solenoid valve 51 and an open command to the solenoid valve 52R. The solenoid valve 51 that receives the spool control command operates so as to realize an opening area corresponding to the spool control command. The solenoid valve 52R that receives the open command switches to the second valve position, and the hydraulic oil discharged by the pilot pump 15 flows into the pipeline C22.

In this way, the attachment control unit 31 generates a spool control command with reference to, for example, a preset operation pattern, and controls the spool position (displacement) of the arm control valve 17B. The arm control valve 17B operates so as to realize, for example, an arm cylinder inflow amount that constitutes an operation pattern.

Further, the attachment control unit 31 functions as an estimator that models the control valve. Attachment control unit 31, for example, based on an output of the information acquisition apparatus 40, control valve derive estimates of the flow rate of the hydraulic oil passing through the (first flow estimate Q ₁₎ (control valve 17B arm in this case). For example, the first flow rate estimation value Qa ₁ is derived using the equation (1).

ｃは流量係数を表し、Ａ_１は制御弁の開口面積を表し、ρは作動油の密度を表し、ΔＰは制御弁の前後の圧力差を表す。ｃ及びρは予め記憶されている値である。ΔＰは、例えば、吐出圧センサ２８の検出値と油圧シリンダのロッド圧センサ又はボトム圧センサの検出値との差として導き出される。具体的には、アーム５を閉じる場合、吐出圧センサ２８の検出値とアームボトム圧センサＳ６ｄの検出値との差として導き出される。また、アーム５を開く場合、吐出圧センサ２８の検出値とアームロッド圧センサＳ６ｃの検出値との差として導き出される。制御弁の開口面積Ａ_１は、スプール制御指令によって決まる値である。

c represents the flow coefficient, A ₁ represents the opening area of the control valve, ρ represents the density of hydraulic oil, and ΔP represents the pressure difference before and after the control valve. c and ρ are values stored in advance. ΔP is derived, for example, as the difference between the detected value of the discharge pressure sensor 28 and the detected value of the rod pressure sensor or the bottom pressure sensor of the hydraulic cylinder. Specifically, when the arm 5 is closed, it is derived as the difference between the detected value of the discharge pressure sensor 28 and the detected value of the arm bottom pressure sensor S6d. Further, when the arm 5 is opened, it is derived as the difference between the detected value of the discharge pressure sensor 28 and the detected value of the arm rod pressure sensor S6c. The opening area A ₁ of the control valve is a value determined by the spool control command.

Further, the attachment control unit 31 based on the output of the information acquisition apparatus 40, the hydraulic cylinder (in this case the arm cylinder 8) derive estimates of the flow rate of the hydraulic oil flowing into the (second flow estimate Q _2). For example, deriving a second flow estimate _{Q 2} using the equation (2).

ｖは油圧シリンダ（ここではアームシリンダ８）の伸縮速度を表し、Ａ_２は油圧シリンダ内のピストンの受圧面積を表す。Ａ_２は予め記憶されている値である。ｖは、例えば、油圧シリンダストロークセンサ（ここではアームシリンダストロークセンサＳ８）の出力から導き出される。

v represents the expansion / contraction speed of the hydraulic cylinder (here, the arm cylinder 8), and A ₂ represents the pressure receiving area of the piston in the hydraulic cylinder. A ₂ is a value stored in advance. v is derived from, for example, the output of the hydraulic cylinder stroke sensor (here, the arm cylinder stroke sensor S8).

Attachment control unit 31, the first and flow estimate Q ₁ calculated by equation (1), corrects the spool control command based on a difference between the second flow estimate Q ₂ to which was calculated by equation (2). This difference is because the actual opening area of the control valve (arm control valve 17B) is considered to be due to not coincide with the opening area A ₁ as the target value. Therefore, attachment control unit 31 corrects the spool control command as the difference for Q _1, Q ₂ is reduced. For example, when Q ₁ is _{larger than Q 2} , the spool control command is corrected so that the actual opening area of the control valve becomes smaller. On the contrary, when Q ₁ is _{smaller than Q 2} , the spool control command is corrected so that the actual opening area of the control valve becomes large.

Next, with reference to FIG. 4, an example of a process when the attachment control unit 31 automatically controls the excavation attachment (hereinafter, referred to as “attachment automatic control process”) will be described. FIG. 4 is a control flow diagram showing an example of the attachment automatic control process. The attachment control unit 31 repeatedly executes this process at a predetermined cycle.

First, the attachment control unit 31 generates a spool control command (step ST1). In this embodiment, the attachment control unit 31 generates a spool control command with reference to an operation pattern stored in NVRAM or the like. Then, the generated spool control command is output to the solenoid valve 51 of the control mechanism 50. The attachment control unit 31 generates a spool control command from each of the hydraulic cylinder inflow amounts (boom cylinder inflow amount, arm cylinder inflow amount, and bucket cylinder inflow amount) constituting the operation pattern, for example. The correspondence between the hydraulic cylinder inflow amount and the spool control command is stored in advance in, for example, NVRAM. Then, the spool control command is separately supplied to the solenoid valve 51 of the control mechanism 50 attached to each of the boom operation lever, the arm operation lever, and the bucket operation lever. Spool control command is, for example, a current command to effect a desired opening area A _{1. “A 1} ′” in FIG. 4 means a current command to bring about an opening area A _1.

When the spool control command is output to the solenoid valve 51, the spool of the control valve corresponding to each hydraulic cylinder is displaced (step ST2). In this embodiment, the spools of the boom control valve 17A, the arm control valve 17B, and the bucket control valve 17C are displaced. The boom control valve 17A, the arm control valve 17B, each of the bucket control valve 17C, displaced to provide a desired opening area A _1.

When the control valve is displaced, a flow rate of hydraulic oil passing through the control valve, that is, a flow rate of hydraulic oil flowing into the hydraulic cylinder is generated (step ST3). In this embodiment, the flow rate of the hydraulic oil flowing into each of the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 is generated through the opening formed by the spool displaced according to the spool control command.

When hydraulic oil flows into the hydraulic cylinder, the hydraulic cylinder expands and contracts (step ST4). In this embodiment, each of the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 expands and contracts at a speed v according to the inflow amount of hydraulic oil.

Then, the attachment control unit 31 corrects the spool control command (step ST5). In this embodiment, the attachment control unit 31 includes a first flow estimate Q ₁ that is calculated by the above equation (1), equation (2) based on the second and flow estimate Q ₂ to which is calculated by the control Correct the spool control command for the valve. _{“A 1} ” in FIG. 4 represents a corrected current command to provide an opening area A _1. Specifically, the spool control commands relating to the boom control valve 17A, the arm control valve 17B, and the bucket control valve 17C are corrected.

In this way, the attachment control unit 31 feeds back the flow rate passing through the control valve, that is, the flow rate flowing into the hydraulic cylinder, and controls the spool displacement (opening area) of the control valve. Therefore, the attachment control unit 31 can more accurately adjust the actual spool displacement (opening area) of the control valve to the target value, and more accurately adjust the actual flow rate of the hydraulic oil flowing into the hydraulic cylinder to the target value. be able to. As a result, the attachment control unit 31 can more accurately control, for example, the posture of the bucket 6 and the position of the toe Pe of the bucket 6. Alternatively, the excavation attachment can be operated more accurately according to a preset operation pattern. That is, it is possible to improve the work efficiency and the finishing accuracy for the target surface (target shape of the ground formed by the excavation operation). Further, since the spool stroke sensor is not required, the manufacturing cost can be reduced.

Next, with reference to FIG. 5, the effect of the correction on the spool control command by the attachment control unit 31 will be described. FIG. 5 is a side view of an excavator showing a state of an excavation attachment that executes an excavation operation according to a preset operation pattern. FIG. 5 (A) shows a relatively early stage of the excavation operation, and FIG. 5 (B) shows a relatively slow stage of the excavation operation. In the example of FIG. 5, the operation pattern is represented by a combination of time-series data (target values) of the boom stroke amount, the arm stroke amount, and the bucket stroke amount. When changing from the state of FIG. 5 (A) to the state of FIG. 5 (B), the boom stroke amount changes from the value DA1 to the value DA2 via a plurality of values, and the arm stroke amount changes from the value DB1 to a plurality of values. The value DB2 changes, and the bucket stroke amount changes from the value DC1 to the value DC2 via a plurality of values.

The broken line TP in FIG. 5A shows a trajectory through which the toe Pe of the bucket 6 passes when the excavation attachment is moved according to a preset operation pattern while correcting the spool control command. As shown in FIG. 5B, this locus coincides with the ground (target surface) after the excavation operation.

The dotted line TPa in FIG. 5A shows the toe Pe of the bucket 6 when the spool control command is not corrected, that is, when the flow rate of the hydraulic oil passing through each control valve cannot be matched with the desired flow rate. Shows the trajectory to pass. As shown in FIG. 5B, this locus does not coincide with the ground (target surface) after the excavation operation. If the spool control command is not corrected, the flow rate of hydraulic oil passing through each control valve, that is, the flow rate of hydraulic oil flowing into each hydraulic cylinder will deviate from the desired flow rate due to the influence of disturbance. Because. Disturbances are, for example, pressure loss in the passageway in the control valve, non-linear and hysteresis characteristics between pilot pressure and spool displacement, hydraulic fluid fluid force, spool sliding friction, excavation reaction acting on the toe Pe of the bucket 6. Includes disturbances related to force F (see white arrow) and the like.

In this way, the attachment control unit 31 can prevent the flow rate of the hydraulic oil passing through each control valve from deviating from the desired flow rate by correcting the spool control command. As a result, the excavation attachment can be operated accurately according to the operation pattern.

Next, with reference to FIG. 6, the relationship between the parameters related to the movement of the excavation attachment will be described. FIG. 6 is a diagram showing the relationship between parameters related to the movement of the excavation attachment.

As shown in FIG. 6, when the position coordinates (Xt, Yt, Zt) of the toe Pe of the bucket 6 at a certain time point are determined, the boom stroke amount, the arm stroke amount, and the bucket stroke amount at that time point are uniquely determined. This means that the boom angle, arm angle, and bucket angle at that time are uniquely determined.

Then, when the boom stroke amount, arm stroke amount, and bucket stroke amount at each of the two arbitrary time points are determined, the boom cylinder extension speed, arm cylinder extension speed, and bucket cylinder extension speed between these two time points are determined. Uniquely determined.

Further, when the boom cylinder extension speed, the arm cylinder extension speed, and the bucket cylinder extension speed are determined, the boom cylinder inflow amount, the arm cylinder inflow amount, and the bucket cylinder inflow amount are uniquely determined.

When the boom cylinder inflow amount, the arm cylinder inflow amount, and the bucket cylinder inflow amount are determined, the spool displacement (opening area) of the boom control valve 17A, the spool displacement (opening area) of the arm control valve 17B, and The spool displacement (opening area) of the bucket control valve 17C is uniquely determined.

Therefore, the attachment control unit 31 controls the spool displacements (opening areas) of the boom control valve 17A, the arm control valve 17B, and the bucket control valve 17C with high accuracy, so that the toe Pe of the bucket 6 The position of can be controlled with high accuracy.

Next, another example of the attachment automatic control process will be described with reference to FIG. 7. FIG. 7 is a control flow diagram showing another example of the attachment automatic control process. The attachment control unit 31 repeatedly executes this process at a predetermined cycle. The control flow diagram of FIG. 7 differs from the control flow diagram of FIG. 4 in that step ST11 and step ST12 are provided before step ST1 and step ST13 is provided after step ST4. On the other hand, it is common with the control flow diagram of FIG. 4 in that it has steps ST1 to ST5. Therefore, the explanation of the common part is omitted, and the difference part is explained in detail.

First, the attachment control unit 31 generates a displacement command (step ST11). The displacement command is a command regarding the displacement of a predetermined portion of the excavation attachment, for example, a command regarding the displacement amount and the displacement direction of the toe Pe of the bucket 6. In this embodiment, the displacement command is a displacement target value indicating the magnitude of displacement (expansion / contraction) of each of the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9. The attachment control unit 31 generates a displacement command with reference to an operation pattern stored in NVRAM or the like. The attachment control unit 31 generates a displacement command from each of the hydraulic cylinder expansion / contraction speeds (boom cylinder expansion / contraction speed, arm cylinder expansion / contraction speed, and bucket cylinder expansion / contraction speed) constituting the operation pattern, for example.

After that, the attachment control unit 31 calculates the target value of the inflow amount of the hydraulic cylinder (step ST12). In this embodiment, the attachment control unit 31 calculates the difference between the displacement target value as the displacement command generated in step ST11 and the actual displacement derived based on the detected value of the cylinder stroke sensor, and based on the difference. Calculate the target value of the hydraulic cylinder inflow amount (boom cylinder inflow amount, arm cylinder inflow amount, and bucket cylinder inflow amount). The target value of the inflow amount of the hydraulic cylinder is calculated so that the larger the displacement target value than the actual displacement, the larger the target value.

Thereafter, the attachment controller 31, as described with reference to FIG. 4, generates a spool control command from the hydraulic cylinder inflow, and, using the first flow estimate Q ₁ and second flow estimate Q ₂ The hydraulic cylinder is expanded and contracted while correcting the spool control command (steps ST1 to ST5).

After that, the attachment control unit 31 calculates the displacement of the hydraulic cylinder (step ST13). In this embodiment, the displacement of the hydraulic cylinder is calculated by integrating (integrating) the expansion and contraction speed of the hydraulic cylinder derived based on the detected value of the cylinder stroke sensor. The calculated displacement is fed back to step ST12 as the actual displacement of the hydraulic cylinder.

In this way, the attachment control unit 31 executes cascade control in which the feedback control is made into a double loop. Specifically, the flow rate passing through the control valve and the flow rate flowing into the hydraulic cylinder are fed back to control the spool displacement (opening area) of the control valve, and the actual displacement of the hydraulic cylinder is fed back to the excavation attachment. Controls the displacement of a predetermined part of. Therefore, the attachment control unit 31 can more accurately adjust the spool displacement (opening area) of the control valve to the target value, and can more accurately adjust the flow rate of the hydraulic oil flowing into the hydraulic cylinder to the target value. In addition, the displacement of a predetermined portion of the excavation attachment can be more accurately adjusted to the target value. As a result, the attachment control unit 31 can more accurately control, for example, the posture of the bucket 6 and the position of the toe Pe of the bucket 6. Alternatively, the excavation attachment can be operated more accurately according to a preset operation pattern.

Although the preferred examples of the present invention have been described in detail above, the present invention is not limited to the above-mentioned examples, and various modifications and substitutions are made to the above-mentioned examples without departing from the scope of the present invention. Can be added.

For example, in the above embodiment, the automatic attachment control process is performed on an excavator equipped with a hydraulic pilot type spool type control valve. However, the present invention is not limited to this configuration. The attachment automatic control process may be performed, for example, on an excavator equipped with an electromagnetic spool type control valve. In this case, the spool control command is directly supplied to the electromagnetic spool type control valve.

Further, in the above-described embodiment, the attachment automatic control process is executed to operate the excavation attachment fully automatically. However, the present invention is not limited to this configuration. The attachment automatic control process may be executed, for example, to operate the excavation attachment semi-automatically. In the attachment automatic control process, for example, when the operator is closing the arm for leveling work or the like, the boom 4 is automatically moved so that the toe Pe of the bucket 6 moves along the target surface (horizontal plane). It may be executed when raising. In this case, the boom cylinder inflow amount (target value) constituting the operation pattern is derived from, for example, the detection value of the operation pressure sensor 29 related to the arm operation lever 26A, the detection value of the arm cylinder stroke sensor S8, and the like.

1 ・ ・ ・ Lower traveling body 1L ・ ・ ・ Left traveling hydraulic motor 1R ・ ・ ・ Right traveling hydraulic motor 2 ・ ・ ・ Swivel mechanism 2A ・ ・ ・ Swivel hydraulic motor 3 ・ ・ ・ Upper swivel body 4 ・ ・ ・ Boom 5 ・・ ・ Arm 6 ・ ・ ・ Bucket 7 ・ ・ ・ Boom cylinder 8 ・ ・ ・ Arm cylinder 9 ・ ・ ・ Bucket cylinder 10 ・ ・ ・ Cabin 11 ・ ・ ・ Engine 13 ・ ・ ・ Regulator 14 ・ ・ ・ Main pump 15 ・ ・・ Pilot pump 17 ・ ・ ・ Control valve 17A ・ ・ ・ Boom control valve 17B ・ ・ ・ Arm control valve 17C ・ ・ ・ Bucket control valve 17D ・ ・ ・ Left travel motor control valve 17E ・ ・ ・ Right travel motor Control valve 17F ・ ・ ・ Control valve for turning 17L ・ ・ ・ Left side pilot port 17R ・ ・ ・ Right side pilot port 26 ・ ・ ・ Operating device 26A ・ ・ ・ Arm operation lever 28 ・ ・ ・ Discharge pressure sensor 29 ・ ・ ・ Operation Pressure sensor 29L, 29R ... Pilot pressure sensor 30 ... Controller 31 ... Attachment control unit 50 ... Control mechanism 51, 52L, 52R ... Solenoid valve C1-C4, C11, C12, C21, C22・ ・ ・ Pipeline

Claims (5)

With the lower running body,
The upper swivel body mounted on the lower traveling body and
The attachment attached to the upper swing body and
The hydraulic cylinder that operates the attachment and
The hydraulic pump mounted on the upper swing body and
A spool-type control valve that controls the flow rate of hydraulic oil flowing from the hydraulic pump to the hydraulic cylinder,
A control device for controlling the displacement of the spool type control valve is provided.
The control device feedback-controls the displacement of the spool-type control valve based on the estimated flow rate of the hydraulic oil passing through the spool-type control valve and the estimated flow rate of the hydraulic oil flowing into the hydraulic cylinder. ,
Excavator. The control device is an estimator that models the spool type control valve.
The excavator according to claim 1. Wherein the control apparatus estimates the flow rate of the hydraulic oil passing through the spool type control valve based on the pressure differential across the spool type control valve,
The excavator according to claim 1 or 2. The control device estimates the flow rate of hydraulic oil flowing into the hydraulic cylinder based on the movement of the hydraulic cylinder.
The excavator according to any one of claims 1 to 3. The control device feedback-controls the displacement of the spool-type control valve based on the difference between the estimated flow rate of the hydraulic oil passing through the spool-type control valve and the estimated flow rate of the hydraulic oil flowing into the hydraulic cylinder. To do,
The excavator according to any one of claims 1 to 4.

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