JP2011157789A - Construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction machine capable of assisting an operator so that working elements can reliably reach the target values of respective operations. <P>SOLUTION: This construction machine includes the working elements which performs respective operations hydraulically, a speed detector for detecting the speeds of the working elements, an operation device operated by the operator to drive the working elements, and a pilot pressure detector for detecting a pilot pressure output from the operation device. A control unit decelerates and stops the working elements using a deceleration pattern selected from among a plurality of deceleration patterns based on the speed detected by the speed detector. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a construction machine that is operated by an operator.

  Generally, a construction machine is designed to perform various operations by being operated by an operator. Many of the operations performed using construction machines are the same operations repeated. For example, excavation and loading operations performed by an excavator as an example of a construction machine are a series of operations in which soil is excavated by a bucket and loaded onto a transport vehicle. Excavation and loading operations performed by such shovels are performed by an operator operating an operation lever in the shovel cab, turning the cabin, and driving work elements such as buckets, arms, and booms.

  Thus, the swiveling of the cabin and the driving of the working elements are left to the operator's control. For this reason, the turning of the cabin and the driving of the working element differ depending on the skill level of the operator. In general, an operator who is unfamiliar with steering cannot operate the steering lever rapidly and greatly. For example, when an operator who is unfamiliar with steering or an operator with low skill level performs an operation to raise the boom to a specified position within a predetermined time, the manipulation lever has to be operated largely, but the manipulation of the manipulation lever is small. In some cases, it is not possible to achieve a speed sufficient to reach the target position within a predetermined time. Alternatively, even if the speed of the boom can be increased, the timing for decelerating to stop at the target position becomes inappropriate, and the boom may overrun due to the delay of the decelerating timing.

  In order to avoid a problem relating to the skill level of the operator, it has been proposed to control the driving of the working element by so-called limit control that limits the operating range of the working device (see, for example, Patent Document 1). That is, an operation range of a work element such as a boom is set, and the operation is automatically limited so that the work element does not move to a position outside the operation range.

  In addition, it has been proposed to control the drive of the work element by trajectory control in which the trajectory of the work element is set in advance and is automatically controlled so that the work element moves through the set trajectory. (For example, refer to Patent Document 2).

Japanese Patent Laid-Open No. 9-291559 Japanese Patent Laid-Open No. 9-291560

  When performing the above-described restriction control, it is possible to prevent the work element from going out of the work range. Therefore, for example, the boom overrun described above can be prevented. However, in the limit control, the position and speed of the work element within the work range cannot be controlled. For example, if the operator stops the operation of the work element within the work range, the operation of the work element stops. Therefore, for example, even if the lever operation amount of the operator is insufficient, control to compensate for this is not performed, and the work element may not reach a desired position.

  Further, when the above-described trajectory control is performed, it takes time to perform an operation for setting a trajectory in advance (for example, setting a program). In addition, precise and strict control is required to control the work element to move along the set trajectory, and the movement speed of the work element must be lower than when the operator steers, Work time will be longer. Furthermore, since the operator does not operate the operation lever, the operator's steering ability is not improved.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a construction machine capable of assisting an operator's operation so that a work element can reliably reach a target value in each work.

  According to one embodiment of the present invention, a working element that performs work by hydraulic pressure, a speed detector that detects a speed of the working element, an operating device that an operator operates to drive the working element, and the operation A pilot pressure detector for detecting a pilot pressure output from the device; and a control device for controlling a driving speed of the working element based on a detection value from the speed detector, wherein the control device is configured to detect the speed. There is provided a construction machine characterized in that the working element is decelerated and stopped using one deceleration pattern selected from among a plurality of deceleration patterns based on the speed detected by the machine.

  In the construction machine described above, the control device is output from the operating device when the pilot pressure is less than a maximum value when the work element moves to a first predetermined position that is close to a target position. The working element is preferably decelerated based on the pilot pressure. The control device outputs an output from the operating device when the pilot pressure is less than a maximum value when the working element moves to the second predetermined position before moving to the first predetermined position. Preferably, the value of the pilot pressure is changed to a maximum value, and the working element is accelerated based on the changed maximum value.

  The control device may perform display indicating that the value of the pilot pressure is changed to the maximum value. Moreover, the said control apparatus is good also as performing the display which shows decelerating by the said deceleration pattern. Furthermore, the deceleration pattern may be selected from at least three different deceleration patterns.

  According to the above-described invention, even if the operator's operation is insufficient, the work element can be reliably driven to the target position, and the desired work can be performed efficiently and reliably regardless of the skill level of the operator. be able to.

It is a side view of a hydraulic excavator. It is a figure which shows the parameter which prescribes | regulates operation | movement of a hydraulic shovel. It is a circuit diagram of the hydraulic circuit of a hydraulic excavator. It is a hydraulic circuit diagram of a pilot pressure generating circuit. It is a figure for demonstrating excavation and loading operation. It is a flowchart of control in the case of assisting the boom raising operation in the dumping operation section automatically. It is a figure which shows the deceleration pattern set beforehand. It is a figure which shows the change of the track | orbit and speed of a boom at the time of assisting boom raising operation by an automatic assist algorithm, and the change of the value of pilot pressure. It is a figure which shows the change of the value of the pilot pressure at the time of stopping a boom. It is a circuit block diagram which shows the other example of a pilot pressure production | generation circuit. It is a circuit block diagram which shows the other example of a pilot pressure production | generation circuit.

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

  First, a hydraulic excavator will be described as an example of a construction machine to which the track control of the work element according to the present invention is applied. The construction machine to which the track control according to the present invention is applied is not limited to a hydraulic excavator.

  FIG. 1 is a side view of a hydraulic excavator. An upper swing body 3 is mounted on the lower traveling body 1 of the hydraulic excavator via a swing mechanism 2. A boom 4 extends from the upper swing body 3, and an arm 5 is connected to the tip of the boom 4. Further, the bucket 6 is connected to the tip of the arm 5. The boom 4, the arm 5, and the bucket 6 are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, respectively. The upper swing body 3 is mounted with a cabin 10 as a cab and an engine (not shown) as a power source. The upper swing body 3 is equipped with a controller 22 as a control device that controls the operation of each part of the excavator. The controller 22 is a control device including a microcomputer and a memory.

  The boom 4 is supported so as to be able to turn up and down with respect to the upper swing body 3, and a boom angle sensor (not shown) is attached to the swing support portion (joint). The boom angle sensor may be any known angle detector, but an inexpensive rotary encoder is preferably used. The boom angle θ1 can be detected by the boom angle sensor. The boom angle θ1 is an inclination angle of the boom 4 from the horizontal direction. Note that the boom angle θ1 is positive in the counterclockwise direction (the direction in which the boom opens) in FIG. Further, the rotation speed of the boom 4, that is, the movement speed of the boom 4 can be detected using the boom angle sensor.

  The arm 5 is supported at the tip of the boom 4 so as to be able to turn, and an arm angle sensor (not shown) is attached to the turning support portion (joint). The arm angle sensor may be any known angle detector, but an inexpensive rotary encoder is preferably used. The arm angle θ2, which will be described later, can be detected by the arm angle sensor. The arm angle θ2 is an inclination angle of the arm 5 from the horizontal direction. The arm angle θ2 is positive in the counterclockwise direction (arm opening direction) in FIG. Further, the rotational speed of the arm 5, that is, the moving speed of the boom 5 can be detected using the arm angle sensor.

  The bucket 6 is supported at the tip of the arm 5 so as to be able to turn, and a bucket angle sensor (not shown) is attached to the turning support portion (joint). The bucket angle sensor may be any known angle detector, but it is preferable to use an inexpensive rotary encoder. A bucket angle θ3 described later can be detected by the bucket angle sensor. Bucket angle θ <b> 3 is an inclination angle of bucket 6 with respect to arm 5. The bucket angle θ3 is positive in the counterclockwise direction (the direction in which the bucket opens) in FIG. Further, the rotational speed of the bucket 6, that is, the moving speed of the bucket 6 can be detected using the bucket angle sensor.

  The turning mechanism 2 for turning the upper turning body 3 is provided with a turning angle sensor (not shown). The turning angle sensor may be any known angle detector, but it is preferable to use an inexpensive rotary encoder. A turning angle θ4 described later can be detected by the turning angle sensor. The turning angle θ4 is an angle from the position where the upper turning body 3 faces the front. Moreover, the turning speed of the upper turning body 3 can be detected using the turning angle sensor.

  The positions of the boom 4, the arm 5 and the bucket 6 can be obtained by calculation using the boom angle θ1, the arm angle θ2, the bucket angle θ3, and the turning angle θ4 as parameters. FIG. 2 is a diagram showing the boom angle θ1, the arm angle θ2, the bucket angle θ3, and the turning angle θ4. In FIG. 2, the height H1 from the ground to the turning support portion of the boom 4 is a known constant value. The distance L1 from the turning support portion of the boom 4 to the turning support portion of the arm 5 is also a known constant value. Furthermore, the distance L2 from the turning support portion of the arm 5 to the turning support portion of the bucket 6 is also a known constant value. The thickness T1 of the bucket 6 is also a known constant value. Therefore, the height HB from the ground to the bucket 6 can be easily obtained by calculating the values of the parameters (θ1 to θ3) in the following formula.

HB = H1 + L1 · sin θ1 + L2 · sin θ2−T1
Further, the height DB of the tip of the bucket 6 can be obtained by the following equation.

DB = H1 + L1 · sin θ1 + L2 · sin θ2 + L3 · sin (θ2 + θ3)
The position of the bucket 6 in the turning direction is represented by a turning angle θ4 detected by a turning angle sensor provided in the turning mechanism 2.

  Here, the hydraulic circuit of the hydraulic excavator will be briefly described. FIG. 3 is a circuit diagram of a hydraulic circuit of the hydraulic excavator.

  As shown in FIG. 3, the discharge oil passage 12 of the variable displacement hydraulic pump 11 is provided with control valves including control valves 13, 14, and 15 for each actuator.

  By operating the operation lever 17a of the pressure reducing valve 17 for the swing motor 16, the spool of the control valve 14 is switched, and the high-pressure hydraulic oil discharged from the hydraulic pump 11 is supplied to the swing motor 16. Rotate in either the left or right direction. Details of the pilot pressure generating circuit including the pressure reducing valve 17 will be described later.

  By operating the operation lever 23 a of the pressure reducing valve 23 for the boom cylinder 7, the spool of the control valve 13 is switched, and the high-pressure hydraulic oil discharged from the hydraulic pump 11 is supplied to the boom cylinder 7. Drive in either direction. Details of the pilot pressure generating circuit including the pressure reducing valve 23 will be described later.

  The hydraulic pump 11 is a variable displacement type, and the discharge amount can be increased or decreased by changing the pump tilt angle by expansion and contraction of the hydraulic cylinder 33. A shuttle valve 36 is connected to the hydraulic cylinder 33 to select and introduce one of the high pressures of the hydraulic oil from the hydraulic source 34 and the hydraulic oil from the negative control oil passage 35. The hydraulic cylinder 33 and the shuttle valve 36 constitute means for changing the discharge amount of the hydraulic pump 11.

  A pressure reducing valve 37 and an electromagnetic switching valve 38 are provided between the hydraulic pressure source 34 and the shuttle valve 36. When the electromagnetic switching valve 38 is opened after the high pressure hydraulic oil from the hydraulic source 34 has been reduced to a predetermined pressure by the pressure reducing valve 37, the hydraulic oil is introduced into the hydraulic cylinder 33 via the shuttle valve 36. When the hydraulic oil is not introduced into the hydraulic cylinder 33 and the piston rod is drawn, the tilt angle of the hydraulic pump 11 becomes large and the discharge amount becomes a large flow rate.

  3 shows a hydraulic circuit for driving the swing motor 16 and a hydraulic circuit for driving the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 for driving the arm 5 and the bucket 6 are the other control valves. And a hydraulic circuit similar to the hydraulic circuit for driving the boom cylinder 7 is provided for each control valve.

  Here, the pilot pressure generating circuit will be described. FIG. 4 is a hydraulic circuit diagram of an example of a pilot pressure generating circuit. The pilot pressure generating circuit shown in FIG. 4 is a hydraulic circuit that generates a pilot pressure when an operator operates a hydraulic lever. In this hydraulic circuit, a pilot operating system valve is used as a control valve. For example, when the operation lever 23a of the pressure reducing valve 23 is tilted to the left, the left pressure reducing valve 23A is pushed downward, and the pilot line 26a and the pilot line 24 are communicated. As a result, the pilot pressure from the pilot hydraulic pump 28 is controlled by the electromagnetic proportional valve C and supplied to the control valve via the pilot lines 26a and 24 and the electromagnetic switching valve B. The greater the operation amount of the operation lever 23a, the more the pressure reducing valve 23A is pushed downward, and a larger pilot pressure is supplied to the control valve. Similarly, when the operation lever 23a is tilted to the right side, the right pressure reducing valve 23B is pushed downward, and the pilot line 26a and the pilot line 25 communicate with each other. As a result, the pilot pressure from the pilot hydraulic pump 28 is supplied to the control valve via the electromagnetic proportional valve C, the pilot lines 26a and 25, and the electromagnetic switching valve B. The greater the operation amount of the operation lever 23a, the more the pressure reducing valve 23B is pushed downward, and a larger pilot pressure is supplied to the control valve. The operation of the pilot pressure generating circuit during automatic operation will be described later. Since the pressure reducing valve 17 is also incorporated in a hydraulic circuit similar to the pilot pressure generating circuit described above, description thereof is omitted.

  Next, an example of work performed using a hydraulic excavator will be described. A typical operation performed using a hydraulic excavator is excavation / loading operation. The excavation / loading operation is a series of operations including an excavation operation and a loading operation. The excavation / loading operation is an operation of excavating and scooping up soil with a bucket and discharging the soil to a predetermined place such as a dump truck bed. Excavation and loading operations are stipulated in detail in the Japan Construction Mechanization Association Standard (JCMAS).

  Excavation / loading operation will be described in more detail with reference to FIG. First, as shown in FIG. 5A, the operator turns the upper swing body 3 so that the bucket 6 is positioned above the excavation position, and the arm 5 is opened and the bucket 6 is also opened. Lowers the boom 4 and lowers the bucket 6 so that the tip of the bucket 6 reaches the target excavation depth D. Usually, turning and boom lowering are operated by an operator, and the position of the bucket 6 is visually confirmed. Further, the turning of the upper swing body 3 and the lowering of the boom 4 are generally performed simultaneously. The above operation is referred to as a boom lowering / turning operation, and this operation section is referred to as a boom lowering / turning operation section.

  If the operator determines that the tip of the bucket 6 has reached the target excavation depth D, then the process moves to a horizontal pulling operation as shown in FIG. In the horizontal pulling operation, the arm 5 is closed until the arm 5 is perpendicular to the ground so that the tip of the bucket 6 moves substantially horizontally. By this horizontal pulling operation, soil having a predetermined depth is excavated and scraped by the bucket 6. When the horizontal pulling operation is completed, the bucket 6 is then closed until it reaches 90 degrees with respect to the arm 5 as shown in FIG. That is, the bucket 6 is closed until the upper edge of the bucket 6 becomes horizontal, and the collected soil is accommodated in the bucket 6. The above operation is called excavation operation, and this operation section is called excavation operation section.

  If the operator determines that the bucket 6 is closed until 90 degrees, then the boom 4 is kept until the bottom of the bucket 6 reaches a predetermined height H with the bucket 6 closed as shown in FIG. Raise. Subsequent to or simultaneously with this, the bucket 6 is swung to a position where the upper swivel body 3 is swung to discharge the earth. The above operation is referred to as a boom raising and turning operation, and this operation section is referred to as a boom raising and turning operation section.

  The boom 4 is raised until the bottom of the bucket 6 reaches a predetermined height H. For example, when the earth is dumped to the loading platform of the dump truck, the bucket 6 becomes the loading platform unless the bucket 6 is lifted higher than the loading platform. This is because they collide. For example, when an unskilled operator is maneuvering, there is a risk of turning without lifting the bucket 6 to a predetermined height H. In such a case, there is a risk of hitting the bucket 6 against the loading platform of the dump truck.

  When the operator determines that the boom raising and turning operation is completed, the operator then opens the arm 5 and the bucket 6 as shown in FIG. This operation is called a dump operation, and this operation section is called a dump operation section. In the dumping operation, only the bucket 6 may be opened and discharged.

  When the operator determines that the dumping operation is completed, the operator then turns the upper swing body 3 to move the bucket 6 directly above the excavation position, as shown in FIG. At this time, the boom 4 is lowered simultaneously with the turning to lower the bucket 6 to the excavation start position. This operation is a part of the boom lowering turning operation described with reference to FIG. The operator lowers the bucket 6 from the excavation start position to the target excavation depth D as shown in FIG. 5A, and performs the excavation operation shown in FIG. 5B again.

  The above “boom lowering turning operation”, “excavation operation”, “boom raising turning operation”, “dump operation”, “boom lowering turning operation” are repeated as one cycle, and excavation / loading is advanced. . Whether or not each operation is completed, that is, whether or not the operation to be performed in each operation section is completed depends on the judgment of the operator. If the operator makes a mistake, one operation section is not completed. In addition, there is a risk of shifting to the next operation section. In addition, in the case of an operator with a low skill level, the work element may not be able to reach the target value due to inexperience in lever operation in one operation section. For this reason, not only is the work efficiency reduced by redoing the operation section that has not been completed, but there is also a possibility that the bucket 6 may be damaged by hitting the dump truck's loading platform.

  Therefore, in the trajectory support control method according to an embodiment of the present invention, the operator sets a target value for the operation of the work element (turning, boom raising, boom lowering, etc.) in each of the above-described operation sections, and clears the target value by the operator. Automatically assists in driving work elements.

  Here, an outline of automatic assist will be described. The term “automatic assist” here means that the construction machine automatically assists the operation of the operator (human), and the construction machine does not perform all work automatically like the trajectory control.

  When the operator operates the operation lever to start driving the work element, the work element is driven according to the lever operation amount by the operator. The lever operation amount of the operator is expressed by pilot pressure, and the controller controls the control valve so as to supply hydraulic pressure determined by the pilot pressure to the work element. Then, the work element is driven based on the value of the pilot pressure until the prescribed value (for example, position) of the work action reaches a predetermined determination value. That is, in order to match the skill level of the operator, the work element is driven according to the lever operation amount of the operator until the prescribed value of the work action reaches the judgment value (threshold value).

  While driving the working element, the pilot pressure is monitored by the controller 22. After the prescribed value of the work operation reaches the judgment value, the pilot pressure input to the control valve is adjusted so that the target value of the work operation is reached. For example, when the operation amount of the operation lever operated by the operator is not the maximum, the maximum value of the pilot pressure is adjusted to be input to the control valve. As a result, the work element is controlled so as to forcefully move toward the target value at the maximum speed.

  When the specified value of the work element approaches the target value, the controller 22 reduces the pilot pressure value, and controls the drive of the work element to stop at the target value. That is, the pilot pressure is gradually reduced to zero in order to prevent the work operation from exceeding the target value (overrun) and stop when the target value is reached. At this time, how to reduce the pilot pressure can be calculated using a “feedback correction table” indicating the relationship between the deviation to the target value and the pilot pressure.

  Hereinafter, an automatic assist algorithm for human operation will be described in more detail with reference to an example of a boom raising operation in the dump operation section. FIG. 6 is a flowchart of control when automatically assisting the boom raising operation in the dump operation section.

  First, in the dumping operation section, when the boom 4 is raised, the height h of the tip of the boom 4 is detected (step S1). The height h of the tip of the boom 4 can be obtained from the angle θ1 of the boom 4 and the length L1 of the boom. Then, when the detected height h reaches a preset determination value h1, it is determined whether or not the operation amount of the operation lever 23a is the maximum value, that is, whether or not the pilot pressure is the maximum value. (Step S2). The judgment value h1 can be set to, for example, half of the target value h0 (h1 = h0 / 2). The target value h0 is a height that the tip of the boom should reach in order to finally lift the bucket 6 to the dump position in the dump operation section.

  If it is determined in step S2 that the lever operation amount (pilot pressure) is not the maximum value (less than the maximum value), the process proceeds to step S3. In step S3, the pilot pressure value is set to the maximum value. Although the actual pilot pressure is less than the maximum value, by setting the pilot pressure value to the maximum value in the control, the operator controls the pilot pressure as if the pilot pressure became the maximum value by maximizing the lever operation.

  The pilot pressure is set to the maximum value by the pilot pressure generating circuit shown in FIG. When it is determined that the assist operation is necessary during acceleration of the boom raising operation, a switching signal is supplied from the storage unit 22a of the controller 22 to the electromagnetic switching valve A (electromagnetic switching valve for boom raising operation), and electromagnetic switching is performed. Valve A is switched. Further, an assist value indicating a pilot pressure required for assist operation during acceleration is supplied from the storage unit 22a of the controller 22 to the electromagnetic proportional valve C. Thereby, the pilot pressure based on the assist value is supplied to the control valve 13 of the control valve, and the boom cylinder 7 is driven. Therefore, the boom 4 automatically performs a boom raising operation with a predetermined acceleration pattern indicated by the assist value.

  Similarly, when it is determined that an assist operation is required during deceleration of the boom raising operation, a switching signal is supplied from the storage unit 22a of the controller 22 to the electromagnetic switching valve A (electromagnetic switching valve for boom raising operation). The electromagnetic switching valve A is switched. Further, an assist value indicating a pilot pressure required for assist operation during deceleration is supplied from the storage unit 22 a of the controller 22 to the electromagnetic proportional valve C. Thereby, the pilot pressure based on the assist value is supplied to the control valve 13 of the control valve, and the boom cylinder 7 is driven. Therefore, the boom 4 automatically performs a boom raising operation with a predetermined deceleration pattern indicated by the assist value.

  Returning to the processing of FIG. 6, when the pilot pressure is changed to the maximum value, the hydraulic oil pressure supplied to the boom cylinder 7 from the control valve 13 that supplies the hydraulic pressure based on the pilot pressure value becomes the maximum, and the boom 4 Is driven with the maximum driving force. Therefore, the boom 4 is accelerated so that the moving speed of the boom 4 (the rotation speed of the boom 4) is maximized.

  In step S3, when the value of the pilot pressure is forcibly set to the maximum value as an assist value to assist the operator's operation, the controller 22 displays “automatic acceleration” on the display in the cab operated by the operator. Display indicating “medium”. Thereby, the operator can recognize that the amount of operation of the operation lever currently operated by himself / herself is insufficient, and can learn that the operation lever needs to be operated more greatly.

  On the other hand, if it is determined in step S2 that the lever operation amount (pilot pressure) is the maximum value, the process proceeds to step S4. Since the pilot pressure value is maximized by the operator's lever operation, the pilot pressure is not changed in step S4, and the process proceeds to step S5. In other words, if the pilot pressure value reaches the maximum value due to the operator's lever operation, the operator determines that the operator is operating the appropriate lever (is an operator skilled in this work) and does not perform automatic assist. To the manual operation of the operator.

  The boom 4 continues to rise while accelerating or at the maximum speed by the automatic assist in step S3 or the manual operation of the operator in step S4. Then, when the height h of the tip of the boom 4 reaches a preset judgment value h2, the speed (rotational speed) of the boom 4 is detected, and it is determined how much the detected speed is. (Step S5). The judgment value h2 can be set to 2/3 of the target value h0 (h2 = 2h0 / 3), for example. The target value h0 is a height that the tip of the boom should reach in order to finally lift the bucket 6 to the dump position in the dump operation section.

  The detected speed is preferably determined in at least three stages, for example, high speed, medium speed, and low speed. The reason for determining the speed here is to know how far the target value must be decelerated in order to stop the rise of the boom 4 at the target value h0. This is because the target value may be overrun unless the speed of the boom 4 is increased and the vehicle is decelerated from the front.

  Subsequently, in step S6, the height h3 at which the boom 4 starts to be decelerated is calculated based on the speed determination result in step S5. The deceleration start height h3 can be obtained by subtracting the braking distance Δh, which is a moving distance necessary for decelerating and stopping, from the target value h0 (h3 = h0−Δh). Here, it is assumed that a braking distance required when the speed of the boom 4 is high is Δh1, a braking distance required when the speed is medium, Δh2, and a braking distance required when the speed is low. The braking distances Δh 1, Δh 2, Δh 3 are obtained in advance and stored in the memory of the controller 22 corresponding to the speed of the boom 4.

  When the calculation of the deceleration start height h3 is completed in step S6, it is subsequently determined in step S7 whether or not automatic acceleration is being performed. That is, it is determined whether the operation of the boom 4 is an automatic assist operation in step S3 or an operator's manual operation in step S4.

  If it is determined in step S7 that automatic acceleration is being performed, the process proceeds to step S8. In step S8, the assist value is output according to the deceleration pattern determined by the braking distance Δh and input to the storage unit 22a, and the boom 4 is decelerated and stopped at the target value h0 when reaching the deceleration start height h3. This deceleration operation is automatically and forcibly performed regardless of the lever operation of the operator. That is, regardless of the pilot pressure generated by the operator's lever operation, the boom 4 is stopped by automatically reducing the control pilot pressure value to zero. If it is determined in step S7 that automatic acceleration is being performed, it means that automatic assist has been performed in step S3, and it can be determined that the skill level of the operator is low. Therefore, in the case of an operator with a low skill level, it is determined that it is preferable to assist even when the boom 4 is stopped, and the boom 4 is automatically stopped at the target value h0 instead of the operator's manual operation.

  In order to automatically stop the boom 4, if it is determined that the speed is high in step S 5, the preset deceleration pattern shown in FIG. 7 from the time when the boom 4 reaches the deceleration start height h 3 = h 0 −Δh 1. The boom 4 is decelerated according to I and stopped at the target value h0. When it is determined that the vehicle speed is medium in step S5, the boom 4 is decelerated according to the preset deceleration pattern II shown in FIG. 7 from the time when the boom 4 reaches the deceleration start height h3 = h0−Δh2. Stop at h0. When it is determined that the speed is low in step S5, the boom 4 is decelerated according to the preset deceleration pattern III shown in FIG. 7 from the point in time when the boom 4 reaches the deceleration start height h3 = h0−Δh3, and the target value h0. Stop at.

  On the other hand, if it is determined in step S7 that automatic acceleration is not being performed, the process proceeds to step S9. In step S9, when the height h of the boom 4 reaches the deceleration start height h3 calculated in step S6 = h0−Δh, the lever operation amount is the maximum value, that is, the actual pilot pressure is the maximum value. It is determined whether or not there is.

  If it is determined in step S9 that the lever operation amount is the maximum value, the process proceeds to step S10. In step S10, as in step S8, the boom 4 is decelerated from the point when the deceleration start height h3 is reached according to the deceleration pattern determined by the braking distance Δh, and stopped at the target value h0. This deceleration operation is automatically and forcibly performed regardless of the lever operation of the operator. That is, regardless of the pilot pressure generated by the operator's lever operation, the boom 4 is stopped by automatically reducing the control pilot pressure value to zero. If it is determined in step S7 that automatic acceleration is not being performed, and the lever operation amount is determined to be the maximum value in step S9, it means that the operator has not yet performed the deceleration operation even though the deceleration has to be performed. That is. Therefore, in this case, it is determined that it is preferable to stop the boom 4 with automatic assist, and the boom 4 is automatically stopped at the target value h0 instead of the manual operation of the operator.

  The process for automatically stopping the boom 4 is the same as the process in step S8. That is, when it is determined that the speed is high in step S5, the boom 4 is decelerated according to the preset deceleration pattern I shown in FIG. 7 from the time when the boom 4 reaches the deceleration start height h3 = h0−Δh1, and the target Stop at value h0. When it is determined that the vehicle speed is medium in step S5, the boom 4 is decelerated according to the preset deceleration pattern II shown in FIG. 7 from the time when the boom 4 reaches the deceleration start height h3 = h0−Δh2. Stop at h0. When it is determined that the speed is low in step S5, the boom 4 is decelerated according to the preset deceleration pattern III shown in FIG. 7 from the point in time when the boom 4 reaches the deceleration start height h3 = h0−Δh3, and the target value h0. Stop at.

  On the other hand, if it is determined in step S9 that the lever operation amount is not the maximum value (less than the maximum value), the process proceeds to step S11. In step S11, the automatic assist is not performed, and the stop of the boom 4 is left to the manual operation of the operator. If it is determined in step S9 that the lever operation amount is not the maximum value (less than the maximum value), this means that the operator has already performed the deceleration operation. It can be determined that the boom 4 can be stopped at h0.

  FIG. 8 is a diagram showing changes in the trajectory and speed of the boom 4 and changes in the pilot pressure when the boom raising operation is assisted by the above-described automatic assist algorithm. 8A shows the height of the boom 4, FIG. 8B shows the speed of the boom 4, and FIG. 8C shows the value of the pilot pressure used for driving the boom. The example shown in FIG. 8 shows a case where an operator with low skill level operates, a solid line shows a change when automatic assist is performed, and a dotted line shows a change when automatic assist is not performed.

  Steps S1 to S2 described above correspond to the operation start period of T0 to T1 in FIG. When the operator starts the boom raising operation at time T0, the automatic assist is not performed until the height h of the boom 4 reaches the judgment value h1, and the boom 4 is driven according to the lever operation of the operator. Accordingly, as shown in FIG. 8A, the height h of the boom 4 changes in the same manner with and without automatic assist, and the speed is also automatically assisted as shown in FIG. 8B. It changes in the same way with and without automatic assist. Moreover, the value of the pilot pressure used for driving the boom 4 is the pilot pressure itself generated by the operation of the operation lever by the operator.

  The process of step S2 described above is a determination performed when the height h of the boom 4 reaches the determination value h1, and this time corresponds to time T1 in FIG. That is, at time T1, it is determined whether or not the operator maximizes the lever operation. When the operator does not maximize the lever operation at time T1, the speed of the subsequent boom 4 is not sufficiently increased, resulting in a change indicated by a dotted line in FIG. In this case, the height h of the boom 4 does not reach the target value h0 as indicated by the dotted line in FIG. Therefore, in step S3 described above, automatic assist is performed to correct the pilot pressure value to be forcibly set to the maximum value. Therefore, as shown by the solid line in FIG. 8C, the change in pilot pressure increases to the maximum value after time T1 and is maintained at the maximum value.

  Thus, by setting the pilot pressure value after time T1 to the maximum value, the speed of the boom 4 increases after time T1, as shown by the solid line in FIG. The height h can reach the target value h0.

  Subsequently, when the height h of the boom 4 reaches the judgment value h2, the process of step S5 described above is performed to determine whether the speed of the boom 4 is high speed, medium speed, or low speed. judge. In FIG. 7, the time point when the height h of the boom 4 reaches the judgment value h2 corresponds to time T2. The determination value h2 is 2/3 of the target value h0, but is not limited to 2/3. This is because the speed of the boom 4 should be almost the maximum if the height is increased to 2/3 of the target value h0, and the braking distance Δh from the speed to the stop can be calculated. If the determination value h2 is too small, the speed of the boom 4 may not reach the maximum value. If the determination value h2 is too large, the distance to the target value h0 may be smaller than the calculated braking distance Δh. There is. The determination value h2 may be appropriately determined in consideration of the above.

  When the braking distance Δh is calculated at time T2, the value of the pilot pressure is maintained at the maximum value until the height (h0−Δh) obtained by subtracting the braking distance Δh from the target value h0 is reached. In FIG. 8, the time point when the height h of the boom 4 becomes (h0−Δh) corresponds to time T3. Therefore, as indicated by the solid line in FIG. 8B, the speed of the boom 4 is maintained at the maximum value until time T3.

  When the boom height h reaches the height (h0−Δh) obtained by subtracting the braking distance Δh from the target value h0 (at time T3), the deceleration of the boom 4 is disclosed, as shown in FIG. As indicated by the solid line, the value of the pilot pressure is gradually reduced. The deceleration pattern at this time is as described with reference to FIG. Deceleration along the deceleration pattern (reduction of the pilot pressure value) is performed until time T4. At time T4, the speed of the boom 4 is substantially zero as indicated by the solid line in FIG. 8B, and the height h of the boom 4 is substantially the target value h0 as indicated by the solid line in FIG. 8A. ing. Therefore, at time T4, the value of the pilot pressure is suddenly reduced to zero, and the boom 4 is stopped. Therefore, the speed of the boom becomes zero when the time T4 has passed as shown by the solid line in FIG. 8B, and the height of the boom 4 has passed when the time T4 has passed as shown by the solid line in FIG. 8A. Reaches the target value h0.

  On the other hand, when automatic assist is not performed, the pilot pressure value remains the pilot pressure generated by the operator's lever operation even after the time T3, as indicated by the dotted line in FIG. Therefore, as indicated by the dotted line in FIG. 8B, the speed of the boom 4 is slow to decrease, and the speed of the boom 4 does not decrease much even at time T4. For this reason, the boom 4 cannot be stopped immediately after the time T4, but stops after a certain amount of time.

  Next, the automatic assist when stopping the boom 4 will be described with reference to FIG. FIG. 9 is a diagram showing a change in the value of the pilot pressure when the boom is stopped.

  In FIG. 9, the solid line shows an example of a deceleration pattern (change in pilot pressure) by lever operation of a skilled operator, and the alternate long and short dash line shows a deceleration pattern (change in pilot pressure) when performing automatic assist according to the present invention. The dotted line shows an example of a deceleration pattern (change in pilot pressure) when the control processing according to the present invention is not applied.

  In the deceleration pattern when the control process according to the present invention indicated by the dotted line is not applied, the pilot pressure is determined by the lever operation of the operator. For this reason, for example, if an operator with low skill level is operating and the lever operation amount remains at the maximum value at time T3, the pilot pressure also remains at the maximum value. Therefore, deceleration is not started even at time T3 when deceleration should be started. Even if the operator rushes at time T4 and decelerates by reducing the lever operation amount, since the deceleration has not started at an appropriate timing, the work element goes too far (the boom rises too high), and quickly. Therefore, it is impossible to perform accurate operation / control.

  On the other hand, in the deceleration pattern by the lever operation of a skilled operator indicated by a solid line, the pilot pressure is the maximum value at time T2 when the boom reaches a height of h1 = h0 / 2. Therefore, in the control process for automatically assisting the boom raising operation shown in FIG. 6, the process proceeds from step S2 to step S4, and it is determined that the correction of the pilot pressure is unnecessary. As a result, it is determined in step S7 that manual acceleration is being performed (not automatic acceleration), and the process proceeds to step S9. Then, at time T3 when the boom height becomes h3 (h0-h), it is determined in step S9 whether or not the lever operation amount is the maximum value. According to the lever operation of a skilled operator, the lever operation amount has already been reduced at time T3, so the pilot pressure is smaller than the maximum value. Therefore, the control process proceeds to step S11, and the deceleration operation ends at time T4.

  Here, in the deceleration pattern in the case of performing the automatic assist according to the present invention indicated by the one-dot chain line, the pilot pressure has the maximum value at time T2 when the boom reaches the height of h1 = h0 / 2. Therefore, in the control process for automatically assisting the boom raising operation shown in FIG. 5, the process proceeds from step S2 to step S4, and it is determined that the correction of the pilot pressure is unnecessary. As a result, it is determined in step S7 that manual acceleration is being performed (not automatic acceleration), and the process proceeds to step S9. In step S9, it is determined whether or not the lever operation amount is the maximum value at time T3 when the boom height is h3 (h0-h). Here, if the lever remains MAX in the manual operation state, the lever operation amount is also the maximum at time T3, so the control process proceeds to step S10, and the automatic operation is performed according to the preset appropriate deceleration pattern. Done.

  As described above, in the hydraulic excavator using the automatic assist algorithm according to the present embodiment, the controller 22 as the control device has a plurality of deceleration patterns based on the speed of the boom 4 as the work element detected by the speed detector. An automatic assist is performed so that the boom 4 is automatically decelerated and stopped using one deceleration pattern selected from the above. For this reason, even when an operator with low skill level operates, the boom 4 as a work element can be stopped appropriately and surely regardless of the operation of the operator.

  Further, when driving the boom 4 as a work element, the boom speed becomes the maximum speed when the boom 4 reaches a predetermined height (1/2 of the target height) after the operation is started. If the speed is less than the maximum speed, automatic assist is performed so that the maximum speed is reached regardless of the operation of the operator. Thereby, even if an operator with low skill level operates, the boom 4 can be reliably moved to the target height regardless of the operation of the operator.

  In the above-described embodiment, an example using a pilot pressure generation circuit using a hydraulic lever has been described. However, a pilot pressure generation circuit using an electric lever may be used.

  FIG. 10 is a circuit diagram of an example of a pilot pressure generating circuit using an electric lever. In FIG. 10, an electric lever 40 is used instead of the hydraulic lever including the pressure reducing valve 23 and the operation lever 23. When the operation lever 40a of the electric lever 40 is operated, a lever operation signal corresponding to the operation amount is supplied from the lever operation signal generation unit 40b to the switching unit 42. The switching unit 42 outputs the lever operation signal to the electromagnetic proportional valve A or the electromagnetic proportional valve B according to the supplied lever operation signal. For example, when it is determined that the supplied lever operation signal is a signal representing raising the boom, the switching unit 42 outputs the lever operation signal to the electromagnetic proportional valve A. Thereby, the hydraulic pressure from the pilot hydraulic pump 28 is controlled by the electromagnetic proportional valve A, and the pilot pressure corresponding to the lever operation amount (boom raising operation amount) is supplied to the control valve. Similarly, when it is determined that the supplied lever operation signal is a signal representing boom lowering, the switching unit 42 outputs the lever operation signal to the electromagnetic proportional valve B. Thereby, the hydraulic pressure from the pilot hydraulic pump 28 is controlled by the electromagnetic proportional valve B, and the pilot pressure corresponding to the lever operation amount (boom lowering operation amount) is supplied to the control valve.

  On the other hand, during the automatic assist operation, the switching unit 42 ignores the lever operation signal from the electric lever 40 and outputs the assist value from the storage unit 22a of the controller 22 to the electromagnetic proportional valve A or the electromagnetic proportional valve B. . For example, when it is determined that an automatic assist operation is required during deceleration in the boom raising operation, the switching unit 42 outputs an assist value based on the deceleration pattern stored in the storage unit 22a to the electromagnetic proportional valve A. Thereby, the pilot pressure corresponding to the deceleration pattern stored in the storage unit 22a is supplied to the control valve via the electromagnetic proportional valve A. Similarly, when it is determined that an automatic assist operation is necessary during acceleration in the boom lowering operation, the switching unit 42 outputs an assist value based on the acceleration pattern stored in the storage unit 22a to the electromagnetic proportional valve B. . Thereby, the pilot pressure corresponding to the acceleration pattern stored in the storage unit 22a is supplied to the control valve via the electromagnetic proportional valve B.

  FIG. 11 is a circuit diagram of another example of a pilot pressure generating circuit using an electric lever. In the pilot pressure generating circuit shown in FIG. 11, the electric signal from the electric lever 40 is supplied to the control valve as it is without using the hydraulic circuit. In this example, not a hydraulic operation system but an electromagnetic operation system control valve is used as the control valve. When the operation lever 40a of the electric lever 40 is operated, a lever operation signal corresponding to the operation amount is supplied from the lever operation signal generation unit 40b to the switching unit 42. The switching unit 42 outputs an electric signal corresponding to the lever operation signal to the control valve according to the supplied lever operation signal. For example, when it is determined that the supplied lever operation signal is a signal representing raising the boom, the switching unit 42 outputs the lever operation signal to the control valve. Thus, the control valve controls the hydraulic pressure from the hydraulic pump 14 and outputs the hydraulic pressure corresponding to the lever operation amount (boom raising operation amount) to the boom cylinder 7. Similarly, when it is determined that the supplied lever operation signal is a signal representing the boom lowering, the switching unit 42 outputs the lever operation signal to the control valve. Thus, the control valve controls the hydraulic pressure from the hydraulic pump 14 and outputs the hydraulic pressure corresponding to the lever operation amount (boom lowering operation amount) to the boom cylinder 7.

  On the other hand, during the automatic assist operation, the switching unit 42 ignores the lever operation signal from the electric lever 40 and outputs the assist value from the storage unit 22a of the controller 22 to the control valve. For example, when it is determined that an automatic assist operation is necessary during deceleration in the boom raising operation, the switching unit 42 outputs an assist value based on the deceleration pattern stored in the storage unit 22a to the control valve. Thereby, an electric signal corresponding to the deceleration pattern stored in the storage unit 22a is supplied to the control valve. Similarly, when it is determined that an automatic assist operation is necessary during acceleration in the boom lowering operation, the switching unit 42 supplies an assist value based on the acceleration pattern stored in the storage unit 22a to the control valve.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Turning mechanism 3 Upper turning body 4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cabin 11 Hydraulic pump 12 Oil path 13, 14, 15 Control valve 16 Swing motor 17, 23 Pressure reducing valve 18 , 19, 24, 25 Secondary side oil passage 22 Controller 22a Storage portion 28 Pilot hydraulic pump 33 Hydraulic cylinder 34 Hydraulic source 35 Negative control oil passage 36 Shuttle valve 37 Pressure reducing valve 38 Electromagnetic switching valve 40 Electric lever 40a Operation lever 40b Lever operation Signal generation unit 42 switching unit

Claims (6)

Working elements to work by hydraulic pressure,
A speed detector for detecting the speed of the working element;
An operating device operated by an operator to drive the working element;
A pilot pressure detector for detecting a pilot pressure output from the operating device;
A control device for controlling the driving speed of the working element based on a detection value from the speed detector;
The construction machine, wherein the control device decelerates and stops the working element using one deceleration pattern selected from a plurality of deceleration patterns based on the speed detected by the speed detector. The construction machine according to claim 1,
The control device, based on the pilot pressure output from the operating device when the pilot pressure is less than a maximum value when the work element moves to a first predetermined position approaching a target position. A construction machine that decelerates the working element. A construction machine according to claim 2,
The control device is output from the operating device when the pilot pressure is less than a maximum value when the working element moves to the second predetermined position before moving to the first predetermined position. A construction machine characterized in that a value of the pilot pressure is changed to a maximum value, and the work element is accelerated based on the changed maximum value. A construction machine according to claim 3,
The construction machine is characterized in that the control device performs a display indicating that the value of the pilot pressure is changed to the maximum value. A construction machine according to any one of claims 1 to 4,
The construction machine is characterized in that the control device displays an indication that the vehicle is decelerating by the deceleration pattern. A construction machine according to any one of claims 1 to 5,
The construction machine, wherein the deceleration pattern is selected from at least three different deceleration patterns.

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