Shovel

Abstract

To provide a shovel having improved operability.SOLUTION: The shovel includes an operation device, a hydraulic actuator, a hydraulic pump for supplying working oil to the hydraulic actuator, an engine for driving the hydraulic pump, control valves for controlling the working oil to be supplied from the hydraulic pump to the hydraulic actuator, solenoid proportional valves connected via pilot lines for supplying a pilot pressure to the control valves, and a control unit for controlling the solenoid proportional valves. The control unit changes the control of the solenoid proportional valve provided in the pilot line on the meter-out side according to the state of the engine or the hydraulic pump.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a shovel.

Background Art

[0002] There is known a working machine including a lower traveling body, an upper revolving body that is rotatable with respect to the lower traveling body, an attachment attached to the upper revolving body, a swing hydraulic motor that swings the upper revolving body, and a hydraulic actuator that drives the attachment. Patent Document 1 discloses an operating device for a hydraulic working machine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By increasing the engine speed and the discharge amount of the hydraulic oil discharged by the pump, the boom raising speed of the shovel can be increased. On the other hand, the boom lowering speed does not change even if the engine speed is increased and the discharge amount of the hydraulic oil discharged by the pump is increased. Therefore, when the engine speed mode is changed, the operation in one operation direction speeds up, and the operation in the other operation direction does not follow, giving the operator a sense of discomfort in operation.

[0005] Therefore, an object of the present invention is to provide a shovel that improves operability.

Means for Solving the Problems

[0006] An embodiment of the present invention of an excavator comprises an operating device, a hydraulic actuator, a hydraulic pump that supplies hydraulic fluid to the hydraulic actuator, an engine that drives the hydraulic pump, a control valve that controls the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator, an electromagnetic proportional valve connected by a pilot line that supplies pilot pressure to the control valve, and a control unit that controls the electromagnetic proportional valve, wherein the control unit controls the state of the engine or the hydraulic pump, For the manipulated variable The solenoid proportional valve is provided in the pilot line on the meter output side. directive Change it. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a shovel with improved operability. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of an excavator according to an embodiment of the present invention. [Figure 2] Figure 1 is a top view of the shovel. [Figure 3] This figure shows an example of the configuration of a hydraulic system installed in the excavator shown in Figure 1. [Figure 4] This is a diagram of a part of the hydraulic system related to the operation of the boom cylinder. [Figure 5] This graph illustrates the limiting control of the proportional valve in a meter-out system. [Figure 6] This flowchart shows an example of controlling a proportional valve using a controller. [Figure 7] This graph shows an example of the relationship between engine speed and boom operating speed. [Modes for carrying out the invention]

[0009] First, with reference to Figures 1 and 2, a shovel 100 as an excavator according to an embodiment of the present invention will be described. Figure 1 is a side view of the shovel 100, and Figure 2 is a top view of the shovel 100.

[0010] In this embodiment, the lower traveling body 1 of the shovel 100 includes a crawler 1C. The crawler 1C is driven by a travel hydraulic motor 2M, which is a travel actuator mounted on the lower traveling body 1. Specifically, the crawler 1C includes a left crawler 1CL and a right crawler 1CR. The left crawler 1CL is driven by a left travel hydraulic motor 2ML, and the right crawler 1CR is driven by a right travel hydraulic motor 2MR.

[0011] An upper rotating body 3 is mounted on the lower traveling body 1 via a rotating mechanism 2 so as to be able to rotate. The rotating mechanism 2 is driven by a rotating hydraulic motor 2A, which is mounted on the upper rotating body 3 as a rotating actuator. However, the rotating actuator may also be a rotating motor generator, which is an electric actuator.

[0012] A boom 4 is attached to the upper slewing body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6, which serves as an end attachment, is attached to the tip of the arm 5. The boom 4, arm 5, and bucket 6 constitute an attachment AT, which is an example of an attachment. The boom 4 is driven by a boom cylinder 7, the arm 5 is driven by an arm cylinder 8, and the bucket 6 is driven by a bucket cylinder 9. The boom cylinder 7, arm cylinder 8, and bucket cylinder 9 constitute an attachment actuator. In the examples shown in Figures 1 and 2, the bucket 6 is an excavation bucket, but it may also be a skeleton bucket or a (gravel removal bucket). The bucket 6 may also be equipped with a bucket tilt mechanism.

[0013] The upper rotating body 3 is equipped with a cabin 10, which serves as the driver's cab, and is also fitted with a power source such as an engine 11. Inside the cabin 10 are an operating device 26, a controller 30, and an operating mode switching device SD. The upper rotating body 3 is also fitted with a spatial recognition device 70. For convenience, in this document, the side of the upper rotating body 3 to which the attachment AT is attached is referred to as the front, and the side to which the counterweight is attached is referred to as the rear.

[0014] The spatial recognition device 70 is configured to recognize objects in the three-dimensional space surrounding the shovel 100. The spatial recognition device 70 may also be configured to calculate the distance from the spatial recognition device 70 or the shovel 100 to the recognized object. The spatial recognition device 70 includes, for example, an ultrasonic sensor, millimeter-wave radar, an imaging device, LIDAR, a distance image sensor, an infrared sensor, etc., or any combination thereof. The imaging device is, for example, a monocular camera or a stereo camera. In this embodiment, the spatial recognition device 70 includes a forward sensor 70F mounted on the front end of the upper surface of the cabin 10, a rear sensor 70B mounted on the rear end of the upper surface of the upper rotating body 3, a left sensor 70L mounted on the left end of the upper surface of the upper rotating body 3, and a right sensor 70R mounted on the right end of the upper surface of the upper rotating body 3. An upward sensor for recognizing objects in the space above the upper rotating body 3 may be mounted on the shovel 100.

[0015] The operating device 26 is a device used by the operator to operate the actuator. The operating device 26 includes, for example, an operating lever and an operating pedal. The actuator includes at least one of a hydraulic actuator and an electric actuator.

[0016] The operation mode switching device SD is configured to be able to switch the operation mode of the operation lever. For example, the operation mode switching device SD includes a push button switch provided on the right console in the cab 10, and is configured to be able to switch the operation mode of the operation lever between a first operation mode and a second operation mode each time the push button switch is pressed. For example, in the first operation mode, when the left operation lever 26L (see FIG. 3) is tilted forward, the arm 5 is opened; when the left operation lever 26L is tilted backward, the arm 5 is closed; when the left operation lever 26L is tilted to the left, a left turn is executed; and when the left operation lever 26L is tilted to the right, a right turn is executed. Also, in the first operation mode, when the right operation lever 26R (see FIG. 3) is tilted forward, the boom 4 is lowered; when the right operation lever 26R is tilted backward, the boom 4 is raised; when the right operation lever 26R is tilted to the left, the bucket 6 is closed; and when the right operation lever 26R is tilted to the right, the bucket 6 is opened. On the other hand, in the second operation mode, when the left operation lever 26L (see FIG. 3) is tilted forward, a right turn is executed; when the left operation lever 26L is tilted backward, a left turn is executed; when the left operation lever 26L is tilted to the left, the arm 5 is opened; and when the left operation lever 26L is tilted to the right, the arm 5 is closed.

[0017] The operator of the excavator 100 may, for example, select the first operation mode when performing an excavation operation using an excavation bucket, and select the second operation mode when performing a debris removal operation using a skeleton bucket (debris removal bucket).

[0018] The controller 30 is a control device for controlling the excavator 100. In the present embodiment, the controller 30 is composed of a computer including a CPU, a volatile memory device, a non-volatile memory device, etc. Then, the controller 30 reads out the program corresponding to each function from the non-volatile memory device and loads it into the volatile memory device, and causes the CPU to execute the corresponding process. Each function includes, for example, a machine guidance function for guiding (guiding) the manual operation of the excavator 100 by the operator, and a machine control function for assisting the manual operation of the excavator 100 by the operator or operating the excavator 100 automatically or autonomously. The controller 30 may include a contact avoidance function for automatically or autonomously operating or stopping the excavator 100 in order to avoid contact between an object existing within the monitoring range around the excavator 100 and the excavator 100. The monitoring of the objects around the excavator 100 is executed not only within the monitoring range but also outside the monitoring range.

[0019] Next, referring to FIG. 3, a configuration example of the hydraulic system mounted on the excavator 100 will be described. FIG. 3 is a diagram showing a configuration example of the hydraulic system mounted on the excavator 100. FIG. 3 shows the mechanical power transmission system, the hydraulic oil line, the pilot line, and the electric control system with double lines, solid lines, broken lines, and dotted lines, respectively.

[0020] The hydraulic system of the excavator 100 mainly includes an engine 11, a regulator 13, a main pump 14, a pilot pump 15, a control valve unit 17, an operation device 26, a discharge pressure sensor 28, an operation sensor 29, and a controller 30, etc.

[0021] In FIG. 3, the hydraulic system is configured such that hydraulic oil can be circulated from the main pump 14 driven by the engine 11 to the hydraulic oil tank through the center bypass pipeline 40 or the parallel pipeline 42.

[0022] The engine 11 is the power source for the shovel 100. In this embodiment, the engine 11 is, for example, a diesel engine that operates to maintain a predetermined rotational speed. The output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15, respectively.

[0023] The main pump 14 is configured to supply hydraulic fluid to the control valve unit 17 via a hydraulic fluid line. In this embodiment, the main pump 14 is a swashplate type variable displacement hydraulic pump.

[0024] The regulator 13 is configured to control the discharge rate of the main pump 14. In this embodiment, the regulator 13 controls the discharge rate of the main pump 14 by adjusting the swash plate tilt angle of the main pump 14 in response to a control command from the controller 30.

[0025] The pilot pump 15 is an example of a pilot pressure generating device and is configured to supply hydraulic fluid to hydraulic control equipment via a pilot line. In this embodiment, the pilot pump 15 is a fixed-displacement hydraulic pump. However, the pilot pressure generating device may be implemented by the main pump 14. That is, the main pump 14 may have the function of supplying hydraulic fluid to the control valve unit 17 via a hydraulic fluid line, as well as the function of supplying hydraulic fluid to various hydraulic control equipment via a pilot line. In this case, the pilot pump 15 may be omitted.

[0026] The control valve unit 17 is a hydraulic control device that controls the hydraulic system in the excavator 100. In this embodiment, the control valve unit 17 includes control valves 171 to 176. Control valve 175 includes control valves 175L and 175R, and control valve 176 includes control valves 176L and 176R. The control valve unit 17 is configured to selectively supply hydraulic fluid discharged by the main pump 14 to one or more hydraulic actuators through the control valves 171 to 176. The control valves 171 to 176 control, for example, the flow rate of hydraulic fluid flowing from the main pump 14 to the hydraulic actuators, and the flow rate of hydraulic fluid flowing from the hydraulic actuators to the hydraulic fluid tank. The hydraulic actuators include a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left travel hydraulic motor 2ML, a right travel hydraulic motor 2MR, and a slewing hydraulic motor 2A.

[0027] The operating device 26 is configured to allow an operator to operate the actuator. In this embodiment, the operating device 26 includes a hydraulic actuator operating device configured to allow an operator to operate a hydraulic actuator. Specifically, the hydraulic actuator operating device is configured to supply hydraulic fluid discharged by the pilot pump 15 to the pilot port of the corresponding control valve in the control valve unit 17 via a pilot line. The pressure of the hydraulic fluid supplied to each pilot port (pilot pressure) is a pressure corresponding to the operating direction and amount of the operating device 26 corresponding to each hydraulic actuator.

[0028] The discharge pressure sensor 28 is configured to detect the discharge pressure of the main pump 14. In this embodiment, the discharge pressure sensor 28 outputs the detected value to the controller 30.

[0029] The operation sensor 29 is configured to detect the content of the operation of the operating device 26 by the operator. In this embodiment, the operation sensor 29 detects the operating direction and amount of operation of the operating device 26 corresponding to each actuator and outputs the detected values ​​to the controller 30.

[0030] The main pump 14 includes a left main pump 14L and a right main pump 14R. The left main pump 14L circulates the hydraulic fluid to the hydraulic fluid tank via the left center bypass pipeline 40L or the left parallel pipeline 42L, while the right main pump 14R circulates the hydraulic fluid to the hydraulic fluid tank via the right center bypass pipeline 40R or the right parallel pipeline 42R.

[0031] The left center bypass pipeline 40L is a hydraulic fluid line that passes through control valves 171, 173, 175L, and 176L located within the control valve unit 17. The right center bypass pipeline 40R is a hydraulic fluid line that passes through control valves 172, 174, 175R, and 176R located within the control valve unit 17.

[0032] The control valve 171 is a spool valve that supplies the hydraulic fluid discharged by the left main pump 14L to the left travel hydraulic motor 2ML, and also switches the flow of hydraulic fluid to discharge the hydraulic fluid discharged by the left travel hydraulic motor 2ML to the hydraulic fluid tank.

[0033] The control valve 172 is a spool valve that supplies the hydraulic fluid discharged by the right main pump 14R to the right travel hydraulic motor 2MR, and also switches the flow of hydraulic fluid to discharge the hydraulic fluid discharged by the right travel hydraulic motor 2MR to the hydraulic fluid tank.

[0034] The control valve 173 is a spool valve that supplies the hydraulic fluid discharged by the left main pump 14L to the swivel hydraulic motor 2A, and also switches the flow of hydraulic fluid to discharge the hydraulic fluid discharged by the swivel hydraulic motor 2A to the hydraulic fluid tank.

[0035] The control valve 174 is a spool valve that supplies the hydraulic fluid discharged by the right main pump 14R to the bucket cylinder 9 and switches the flow of the hydraulic fluid in order to discharge the hydraulic fluid in the bucket cylinder 9 to the hydraulic fluid tank.

[0036] Control valve 175L is a spool valve that switches the flow of hydraulic fluid to supply the hydraulic fluid discharged by the left main pump 14L to the boom cylinder 7. Control valve 175R is a spool valve that supplies the hydraulic fluid discharged by the right main pump 14R to the boom cylinder 7 and also switches the flow of hydraulic fluid to discharge the hydraulic fluid inside the boom cylinder 7 to the hydraulic fluid tank.

[0037] The control valve 176L is a spool valve that supplies the hydraulic fluid discharged by the left main pump 14L to the arm cylinder 8 and also switches the flow of the hydraulic fluid in order to discharge the hydraulic fluid in the arm cylinder 8 to the hydraulic fluid tank.

[0038] The control valve 176R is a spool valve that supplies the hydraulic fluid discharged by the right main pump 14R to the arm cylinder 8 and switches the flow of the hydraulic fluid in order to discharge the hydraulic fluid in the arm cylinder 8 to the hydraulic fluid tank.

[0039] The left parallel pipeline 42L is a hydraulic fluid line running parallel to the left center bypass pipeline 40L. The left parallel pipeline 42L can supply hydraulic fluid to a control valve further downstream if the flow of hydraulic fluid through the left center bypass pipeline 40L is restricted or blocked by any of the control valves 171, 173, and 175L. The right parallel pipeline 42R is a hydraulic fluid line running parallel to the right center bypass pipeline 40R. The right parallel pipeline 42R can supply hydraulic fluid to a control valve further downstream if the flow of hydraulic fluid through the right center bypass pipeline 40R is restricted or blocked by any of the control valves 172, 174, and 175R.

[0040] The regulator 13 includes a left regulator 13L and a right regulator 13R. The left regulator 13L controls the discharge volume of the left main pump 14L by adjusting the swash plate tilt angle of the left main pump 14L in accordance with the discharge pressure of the left main pump 14L. Specifically, the left regulator 13L reduces the discharge volume by adjusting the swash plate tilt angle of the left main pump 14L in accordance with an increase in the discharge pressure of the left main pump 14L. The same applies to the right regulator 13R. This is to ensure that the absorption power (absorption horsepower) of the main pump 14, which is expressed as the product of the discharge pressure and the discharge volume, does not exceed the output power (output horsepower) of the engine 11.

[0041] The operating device 26 includes a left operating lever 26L, a right operating lever 26R, and a travel lever 26D. The travel lever 26D includes a left travel lever 26DL and a right travel lever 26DR.

[0042] The left operating lever 26L is used for slewing and operating the arm 5. When the left operating lever 26L is operated in the forward / backward direction, it uses the hydraulic fluid discharged by the pilot pump 15 to introduce a control pressure corresponding to the lever operation amount into the pilot port of the control valve 176. When it is operated in the left / right direction, it uses the hydraulic fluid discharged by the pilot pump 15 to introduce a control pressure corresponding to the lever operation amount into the pilot port of the control valve 173.

[0043] Specifically, when the left operating lever 26L is operated in the arm closing direction, it introduces hydraulic fluid into the right pilot port of control valve 176L and into the left pilot port of control valve 176R. When the left operating lever 26L is operated in the arm opening direction, it introduces hydraulic fluid into the left pilot port of control valve 176L and into the right pilot port of control valve 176R. Furthermore, when the left operating lever 26L is operated in the left rotation direction, it introduces hydraulic fluid into the left pilot port of control valve 173, and when operated in the right rotation direction, it introduces hydraulic fluid into the right pilot port of control valve 173.

[0044] In the example shown in Figure 3, the left control lever 26L functions as an arm control lever when operated in the forward / backward direction and as a swivel control lever when operated in the left / right direction.

[0045] The right operating lever 26R is used to operate the boom 4 and the bucket 6. When the right operating lever 26R is operated in the forward / backward direction, it uses the hydraulic fluid discharged by the pilot pump 15 to introduce a control pressure corresponding to the lever operation amount into the pilot port of the control valve 175. When it is operated in the left / right direction, it uses the hydraulic fluid discharged by the pilot pump 15 to introduce a control pressure corresponding to the lever operation amount into the pilot port of the control valve 174.

[0046] Specifically, when the right operating lever 26R is operated in the boom lowering direction, it introduces hydraulic fluid into the left pilot port of the control valve 175R. When the right operating lever 26R is operated in the boom raising direction, it introduces hydraulic fluid into the right pilot port of the control valve 175L and into the left pilot port of the control valve 175R. Furthermore, when the right operating lever 26R is operated in the bucket closing direction, it introduces hydraulic fluid into the right pilot port of the control valve 174, and when it is operated in the bucket opening direction, it introduces hydraulic fluid into the left pilot port of the control valve 174.

[0047] In the example shown in Figure 3, the right operating lever 26R functions as a boom operating lever when operated in the forward / backward direction and as a bucket operating lever when operated in the left / right direction.

[0048] The travel lever 26D is used to operate the crawler 1C. Specifically, the left travel lever 26DL is used to operate the left crawler 1CL. It may be configured to be linked with the left travel pedal. When the left travel lever 26DL is operated in the forward / backward direction, it uses the hydraulic fluid discharged by the pilot pump 15 to introduce a control pressure corresponding to the lever operation amount into the pilot port of the control valve 171. The right travel lever 26DR is used to operate the right crawler 1CR. It may be configured to be linked with the right travel pedal. When the right travel lever 26DR is operated in the forward / backward direction, it uses the hydraulic fluid discharged by the pilot pump 15 to introduce a control pressure corresponding to the lever operation amount into the pilot port of the control valve 172.

[0049] The discharge pressure sensor 28 includes discharge pressure sensors 28L and 28R. Discharge pressure sensor 28L detects the discharge pressure of the left main pump 14L and outputs the detected value to the controller 30. The same applies to discharge pressure sensor 28R.

[0050] The operation sensor 29 includes operation sensors 29LA, 29LB, 29RA, 29RB, 29DL, and 29DR. Operation sensor 29LA detects the operator's forward and backward movement of the left operation lever 26L and outputs the detected value to the controller 30. The operation details include, for example, the direction of lever operation and the amount of lever operation (lever operation angle).

[0051] Similarly, the operation sensor 29LB detects the operator's left-right operation of the left operation lever 26L and outputs the detected value to the controller 30. The operation sensor 29RA detects the operator's forward-backward operation of the right operation lever 26R and outputs the detected value to the controller 30. The operation sensor 29RB detects the operator's left-right operation of the right operation lever 26R and outputs the detected value to the controller 30. The operation sensor 29DL detects the operator's forward-backward operation of the left travel lever 26DL and outputs the detected value to the controller 30. The operation sensor 29DR detects the operator's forward-backward operation of the right travel lever 26DR and outputs the detected value to the controller 30.

[0052] The controller 30 receives the output of the operation sensor 29 and, if necessary, outputs a control command to the regulator 13 to change the discharge amount of the main pump 14. The controller 30 also receives the output of the control pressure sensor 19 located upstream of the throttle 18 and, if necessary, outputs a control command to the regulator 13 to change the discharge amount of the main pump 14. The throttle 18 includes a left throttle 18L and a right throttle 18R, and the control pressure sensor 19 includes a left control pressure sensor 19L and a right control pressure sensor 19R.

[0053] In the left center bypass pipeline 40L, a left throttle 18L is located between the control valve 176L, the downstreammost control valve, and the hydraulic fluid tank. Therefore, the flow of hydraulic fluid discharged by the left main pump 14L is restricted by the left throttle 18L. The left throttle 18L then generates a control pressure to control the left regulator 13L. The left control pressure sensor 19L is a sensor for detecting this control pressure and outputs the detected value to the controller 30. The controller 30 controls the discharge amount of the left main pump 14L by adjusting the swash plate tilt angle of the left main pump 14L in accordance with this control pressure. The controller 30 decreases the discharge amount of the left main pump 14L as the control pressure increases, and increases the discharge amount of the left main pump 14L as the control pressure decreases. The discharge amount of the right main pump 14R is controlled in the same way.

[0054] Specifically, as shown in Figure 3, when none of the hydraulic actuators in the shovel 100 are operated and the system is in standby mode, the hydraulic fluid discharged from the left main pump 14L passes through the left center bypass pipe 40L to the left constrictor 18L. The flow of hydraulic fluid discharged from the left main pump 14L increases the control pressure generated upstream of the left constrictor 18L. As a result, the controller 30 reduces the discharge volume of the left main pump 14L to the minimum allowable discharge volume, suppressing pressure loss (pumping loss) as the discharged hydraulic fluid passes through the left center bypass pipe 40L. On the other hand, when any of the hydraulic actuators are operated, the hydraulic fluid discharged from the left main pump 14L flows into the hydraulic actuator being operated via the control valve corresponding to that actuator. The flow of hydraulic fluid discharged from the left main pump 14L reduces or eliminates the amount reaching the left constrictor 18L, lowering the control pressure generated upstream of the left constrictor 18L. As a result, the controller 30 increases the discharge volume of the left main pump 14L, circulating sufficient hydraulic fluid to the hydraulic actuator being operated, and ensuring reliable operation of the hydraulic actuator. The controller 30 also controls the discharge volume of the right main pump 14R in the same manner.

[0055] With the configuration described above, the hydraulic system in Figure 3 can suppress unnecessary energy consumption in the main pump 14 when in standby mode. Unnecessary energy consumption includes pumping losses caused by the hydraulic fluid discharged by the main pump 14 in the center bypass pipeline 40. Furthermore, when operating a hydraulic actuator, the hydraulic system in Figure 3 can reliably supply the necessary and sufficient hydraulic fluid from the main pump 14 to the hydraulic actuator being operated.

[0056] Furthermore, boom cylinder 7 is equipped with boom rod pressure sensor S7R and boom bottom pressure sensor S7B. Arm cylinder 8 is equipped with arm rod pressure sensor S8R and arm bottom pressure sensor S8B. Bucket cylinder 9 is equipped with bucket rod pressure sensor S9R and bucket bottom pressure sensor S9B. The boom rod pressure sensor S7R, boom bottom pressure sensor S7B, arm rod pressure sensor S8R, arm bottom pressure sensor S8B, bucket rod pressure sensor S9R, and bucket bottom pressure sensor S9B are collectively referred to as "cylinder pressure sensors". In addition, the swing hydraulic motor 2A is equipped with left swing pressure sensor S10L and right swing pressure sensor S10R.

[0057] The boom rod pressure sensor S7R 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 S7B detects the pressure in the bottom-side oil chamber of the boom cylinder 7 (hereinafter referred to as "boom bottom pressure"). The arm rod pressure sensor S8R 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 S8B detects the pressure in the bottom-side oil chamber of the arm cylinder 8 (hereinafter referred to as "arm bottom pressure"). The bucket rod pressure sensor S9R 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 S9B detects the pressure in the bottom-side oil chamber of the bucket cylinder 9 (hereinafter referred to as "bucket bottom pressure"). The left slewing pressure sensor S10L detects the hydraulic fluid pressure at the left port of the slewing hydraulic motor 2A. The right slewing pressure sensor S10R detects the hydraulic fluid pressure at the right port of the slewing hydraulic motor 2A. The values ​​detected by each sensor are transmitted to the controller 30.

[0058] Next, referring to Figure 4, the configuration for the controller 30 to operate the actuator by machine control function will be described. Figure 4 is an excerpt of a part of the hydraulic system. Specifically, Figure 4 is an excerpt of the hydraulic system part related to the operation of the boom cylinder 7.

[0059] As shown in Figure 4, the hydraulic system includes a proportional valve 31. The proportional valve 31 includes proportional valves 31BL and 31BR.

[0060] The proportional valve 31 functions as a control valve for machine control. The proportional valve 31 is located in a pipeline connecting the pilot pump 15 and the pilot port of the corresponding control valve in the control valve unit 17, and is configured to change the flow area of ​​the pipeline. In this embodiment, the proportional valve 31 operates in response to control commands output by the controller 30. Therefore, the controller 30 can supply the hydraulic fluid discharged by the pilot pump 15 to the pilot port of the corresponding control valve in the control valve unit 17 via the proportional valve 31, independently of the operator's operation of the operating device 26. The controller 30 can then apply the pilot pressure generated by the proportional valve 31 to the pilot port of the corresponding control valve.

[0061] This configuration allows the controller 30 to operate the hydraulic actuator corresponding to a specific operating device 26 even when no operation is being performed on that device. Furthermore, the controller 30 can forcibly stop the operation of the hydraulic actuator corresponding to a specific operating device 26 even when an operation is being performed on that device.

[0062] For example, as shown in Figure 4, the right operating lever 26R is used to operate the boom 4. Specifically, the right operating lever 26R uses the hydraulic fluid discharged by the pilot pump 15 to apply pilot pressure to the pilot port of the control valve 175 in accordance with the operation in the forward and backward directions. More specifically, when the right operating lever 26R is operated in the boom-raising direction (rearward direction), it applies pilot pressure to the left pilot port of the control valve 175R in accordance with the amount of operation. Also, when the right operating lever 26R is operated in the boom-lower direction (forward direction), it applies pilot pressure to the right pilot port of the control valve 175R in accordance with the amount of operation.

[0063] The operation sensor 29RA detects the operator's forward and backward movement of the right operation lever 26R and outputs the detected value to the controller 30.

[0064] The proportional valve 31BL operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure using the hydraulic fluid introduced from the pilot pump 15 to the left pilot port of the control valve 175R via the proportional valve 31BL. The proportional valve 31BR operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure using the hydraulic fluid introduced from the pilot pump 15 to the right pilot port of the control valve 175R via the proportional valve 31BR. The proportional valve 31BL can adjust the pilot pressure so that the control valve 175R can be stopped at any valve position. Similarly, the proportional valve 31BR can adjust the pilot pressure so that the control valve 175R can be stopped at any valve position.

[0065] Furthermore, a pilot pressure sensor 32BL for detecting pilot pressure is provided on the pilot line connecting the proportional valve 31BL to one port of the control valve 175 (the left port of the control valve 175R). Additionally, a pilot pressure sensor 32BR for detecting pilot pressure is provided on the pilot line connecting the proportional valve 31BR to the other port of the control valve 175 (the right port of the control valve 175R). The values ​​detected by each pilot pressure sensor 32BL and 32BR are transmitted to the controller 30.

[0066] With this configuration, the controller 30 can supply hydraulic fluid discharged by the pilot pump 15 to the left pilot port of the control valve 175R via the proportional valve 31BL in response to the boom raising operation by the operator. In addition, the controller 30 can supply hydraulic fluid discharged by the pilot pump 15 to the left pilot port of the control valve 175R via the proportional valve 31BL, independently of the boom raising operation by the operator. In other words, the controller 30 can raise the boom 4 in response to the boom raising operation by the operator, or independently of the boom raising operation by the operator.

[0067] Furthermore, the controller 30 can supply hydraulic fluid discharged by the pilot pump 15 to the right pilot port of the control valve 175R via the proportional valve 31BR in response to the boom lowering operation by the operator. In addition, the controller 30 can supply hydraulic fluid discharged by the pilot pump 15 to the right pilot port of the control valve 175R via the proportional valve 31BR, independently of the boom lowering operation by the operator. In other words, the controller 30 can lower the boom 4 in response to the boom lowering operation by the operator, or independently of the boom lowering operation by the operator.

[0068] In Figure 4, the controller 30 controls proportional valves 31BL and 31BR and supplies pilot pressure to the control valve 175R. Similarly, the controller 30 controls a proportional valve (not shown) and supplies pilot pressure to the control valve 175L.

[0069] Furthermore, with this configuration, even when the operator is raising the boom, the controller 30 can, if necessary, reduce the pilot pressure acting on the boom-raising pilot port of the control valve 175 (the left pilot port of the control valve 176R and the right pilot port of the control valve 175L), thereby forcibly stopping the raising operation of the boom 4. The same applies when the operator is lowering the boom and the lowering operation of the boom 4 needs to be forcibly stopped.

[0070] Furthermore, although a detailed explanation will be omitted, the same applies when the operation of arm 5 is forcibly stopped when the operator is performing an arm opening or closing operation, when the operation of bucket 6 is forcibly stopped when the operator is performing a bucket closing or bucket opening operation, and when the rotational movement of the upper slewing body 3 is forcibly stopped when the operator is performing a slewing operation. The same also applies when the movement of the lower traveling body 1 is forcibly stopped when the operator is performing a travel operation.

[0071] The shovel 100 may be configured to automatically move the lower travel body 1 forward and backward. In this case, the hydraulic system portion for operating the left travel hydraulic motor 2ML and the hydraulic system portion for operating the right travel hydraulic motor 2MR may be configured in the same way as the hydraulic system portion for operating the boom cylinder 7, etc.

[0072] Furthermore, although the description of the operating device 26 is based on an electric operating lever, a hydraulic operating lever may also be used instead. In this case, the amount of lever operation of the hydraulic operating lever may be detected in the form of pressure by a pressure sensor and input to the controller 30. Also, a solenoid valve may be placed between the operating device 26 as a hydraulic operating lever and the pilot port of each control valve. The solenoid valve is configured to operate in response to an electrical signal from the controller 30. With this configuration, when manual operation is performed using the operating device 26 as a hydraulic operating lever, the operating device 26 can move each control valve by increasing or decreasing the pilot pressure according to the amount of lever operation. Also, each control valve may be composed of an electromagnetic spool valve. In this case, the electromagnetic spool valve operates in response to an electrical signal from the controller 30 corresponding to the amount of lever operation of the electric operating lever.

[0073] Here, we will explain the operation of raising the boom 4 by supplying hydraulic fluid (meter-in) from the main pump 14 to the bottom oil chamber of the boom cylinder 7. When the operator operates the operating device 26, the controller 30 controls the opening degree of the proportional valve 31BL according to the amount of operation of the operating device 26 and supplies pilot pressure to the left port of the control valve 175R. The controller 30 also controls the opening degree of the proportional valve (not shown) according to the amount of operation of the operating device 26 and supplies pilot pressure to the right port of the control valve 175L. As a result, hydraulic fluid is supplied from the main pump 14 to the bottom oil chamber of the boom cylinder 7.

[0074] Here, by increasing the rotational speed of the engine 11 and increasing the pumping torque of the main pump 14, the flow rate of the hydraulic fluid supplied from the main pump 14 increases, and the lifting speed of the boom 4 in relation to the amount of operation of the operating device 26 can be increased. Conversely, by decreasing the rotational speed of the engine 11 and decreasing the pumping torque of the main pump 14, the flow rate of the hydraulic fluid supplied from the main pump 14 decreases, and the lifting speed of the boom 4 in relation to the amount of operation of the operating device 26 can be decreased.

[0075] Next, we will explain the operation of lowering the boom 4 by discharging (metering out) hydraulic fluid from the bottom oil chamber of the boom cylinder 7 into the hydraulic fluid tank. When the operator operates the operating device 26, the controller 30 controls the opening degree of the proportional valve 31BR according to the amount of operation of the operating device 26 and supplies pilot pressure to the right port of the control valve 175R. The controller 30 also sets the spool of the control valve 175L to the neutral position. As a result, hydraulic fluid is discharged from the bottom oil chamber of the boom cylinder 7 into the hydraulic fluid tank.

[0076] Here, even if the rotational speed of the engine 11 is increased or the pumping torque of the main pump 14 is increased, the lowering speed of the boom 4 in relation to the amount of operation of the control device 26 does not change. Similarly, even if the rotational speed of the engine 11 is decreased or the pumping torque of the main pump 14 is decreased, the lowering speed of the boom 4 in relation to the amount of operation of the control device 26 does not change.

[0077] Therefore, if the operator increases the rotational speed of the engine 11 or increases the pumping torque of the main pump 14 in order to increase the operating speed of the boom 4, the raising speed of the boom 4 will increase, but the lowering speed of the boom 4 will not change. This causes the operator to feel uneasy when operating the equipment. Also, if the operator decreases the rotational speed of the engine 11 or decreases the pumping torque of the main pump 14 in order to decrease the operating speed of the boom 4, the raising speed of the boom 4 will decrease, but the lowering speed of the boom 4 will not change. This also causes the operator to feel uneasy when operating the equipment.

[0078] Next, the control in the shovel 100 according to this embodiment will be explained using Figure 5. Figure 5 is a graph illustrating the limiting control of the proportional valve 31 in meter-out.

[0079] The first control example will be explained using Figures 5(a) and 5(b). Figure 5(a) is a graph showing the relationship between the amount of operation of the operating device 26 (lever operation amount) and the pilot pressure supplied from the proportional valve 31BL to the control valve 175 when the boom 4 is lowered. Here, the pilot pressure when the engine speed is low is shown by a dashed line, the pilot pressure when the engine speed is medium is shown by a dotted line, and the pilot pressure when the engine speed is high is shown by a solid line. Figure 5(b) is a graph showing the relationship between the engine speed of the engine 11 and the maximum pilot pressure.

[0080] In the first control example, the controller 30 controls the proportional valve 31 to limit the maximum pilot pressure according to the engine speed. As shown in Figure 5(b), the controller 30 controls the proportional valve 31 so that the maximum pilot pressure increases as the engine speed increases. Also, the controller 30 controls the proportional valve 31 so that the maximum pilot pressure decreases as the engine speed decreases.

[0081] As a result, as shown in Figure 5(a), when the engine speed is low (shown by a dashed line in Figure 5(a)), the maximum value of the pilot pressure is limited to be lower compared to when the engine speed is high (shown by a solid line in Figure 5(a)). In this example, the pilot pressure reaches its maximum value when the lever operation amount reaches ST1. As a result, when the engine speed is low, the opening area of ​​the control valve 175 is limited, and the flow rate of hydraulic fluid discharged from the bottom chamber to the hydraulic fluid tank is also reduced. This makes it possible to reduce the lowering speed of the boom 4 when the engine speed is low. This makes it possible to reduce discomfort for the operator.

[0082] The second control example will be explained using Figure 5(c). Figure 5(c) is a graph showing the relationship between the amount of operation of the control device 26 (lever operation amount) and the pilot pressure when lowering the boom 4. Here, the pilot pressure when the engine speed is low is shown by a dashed line, the pilot pressure when the engine speed is medium is shown by a dotted line, and the pilot pressure when the engine speed is high is shown by a solid line.

[0083] In the second control example, the controller 30 controls the proportional valve 31 so that the pilot pressure in response to the lever operation amount increases as the engine speed increases. In other words, the slope of the pilot pressure in response to the lever operation amount increases as the engine speed increases. Also, in the second control example, the pilot pressure at the maximum lever operation amount is different. In other words, the controller 30 limits the maximum pilot pressure depending on the engine speed.

[0084] As a result, as shown in Figure 5(c), when the engine speed is low, the pilot pressure relative to the lever operation amount is reduced compared to when the engine speed is high. This limits the opening area of ​​the control valve 175 when the engine speed is low, and also reduces the flow rate of hydraulic fluid discharged from the bottom chamber to the hydraulic fluid tank. As a result, when the engine speed is low, the lowering speed of the boom 4 can be reduced. This reduces discomfort for the operator.

[0085] A third control example will be explained using Figures 5(d) and 5(e). Figure 5(d) is a graph showing the time change of the operating amount (lever operating amount) and pilot pressure of the operating device 26 when the boom 4 is lowered. Here, the lever operating amount is shown by a dashed line. The time change of pilot pressure when the engine speed is low is shown by a dashed line, and the time change of pilot pressure when the engine speed is high is shown by a solid line. Figure 5(e) is a graph showing the relationship between the engine speed of the engine 11 and the pilot pressure increase limit.

[0086] In the third control example, the controller 30 limits the increase in pilot pressure based on engine speed.

[0087] Specifically, when the operating device 26 is operated as shown by the dashed line and the engine speed is high, the controller 30 controls the proportional valve 31 to increase the rate of increase of the pilot pressure, as shown by the solid line. This controls the proportional valve 31 so that the pilot pressure rises quickly. In addition, the control valve 175 opens quickly, and the operating speed of the boom 4's lowering operation increases rapidly. In this example, the pilot pressure increases until time T1, and then remains constant thereafter.

[0088] On the other hand, when the operating device 26 is operated as shown by the dashed line and the engine speed is low, the controller 30 controls the proportional valve 31 to reduce the rate at which the pilot pressure increases, as shown by the dashed line. This controls the proportional valve 31 so that the pilot pressure rises gradually. Also, the control valve 175 opens gradually, and the operating speed of the boom 4's lowering operation increases gradually. In this example, the pilot pressure increases for a time T2 which is longer than time T1, and then the pilot pressure remains constant after time T2. This makes it possible to reduce the lowering speed of the boom 4 when the engine speed is low. This reduces discomfort for the operator.

[0089] In the first to third control examples, the pilot pressure is limited based on engine speed, but this is not the only way to do so. The pilot pressure may be limited based on pump torque instead of engine speed. As described above, in the first to third control examples, the maximum value of the pilot pressure is limited, or the rate at which the pilot pressure increases is limited. Specifically, in the first control example, only the maximum value of the pilot pressure is limited. In the second example, the maximum value of the pilot pressure is limited, and the rate at which the pilot pressure increases is also limited. In the third control example, only the rate at which the pilot pressure increases is limited.

[0090] Next, the control of the controller 30 will be explained using Figure 6. Figure 6 is a flowchart showing an example of the control of the proportional valve 31 by the controller 30.

[0091] In step S101, the controller 30 reads the status of either the engine 11 or the main pump 14. Specifically, the controller 30 reads at least one of the following: the engine speed of the engine 11, the pump torque of the main pump 14, or the working mode of the shovel 100. The working mode includes information on engine speed and pump torque.

[0092] When an operator operates the control device 26, the amount of operation of the control device 26 is input to the controller 30. In step S102, the controller 30 makes a determination of the operation of the control device 26.

[0093] If the operation of the operating device 26 is determined to be a boom raising operation (meter-in operation), the controller 30 proceeds to step S103. In step S103, the controller 30 issues a command to the electromagnetic proportional valve (proportional valve 31) using the normal profile. That is, the controller 30 controls the opening degree of the proportional valve 31 based on the amount of operation of the operating device 26. Here, the normal profile is a control that does not limit the pilot pressure relative to the amount of lever operation. In other words, in the normal profile, the control does not change the command based on the amount of operation of the operating device 26 based on the state of the engine 11 or the main pump 14 (engine speed, pump torque, working mode).

[0094] If the operation of the operating device 26 is determined to be a boom lowering operation (meter-out operation), the controller 30 proceeds to step S104. In step S104, the controller 30 issues a command to the electromagnetic proportional valve (proportional valve 31) using a limiting profile. In other words, the controller 30 modifies the command based on the amount of operation of the operating device 26 based on the state of the engine 11 or main pump 14 (engine speed, pump torque, working mode), and issues the modified command to the electromagnetic proportional valve (proportional valve 31). This corrects the pilot pressure for the amount of operation of the operating device 26. That is, the controller 30 controls the opening degree of the proportional valve 31 using the control shown in Figure 5, based on the amount of operation of the operating device 26 and the state of the engine 11 or main pump 14 (engine speed, pump torque, working mode). Here, the limiting profile means controlling with one of the profiles shown in Figure 5(a), (c), or (d). These profiles may also be used in combination.

[0095] Figure 7 is a graph showing an example of the relationship between engine speed and the operating speed of boom 4. In Figure 7, the horizontal axis represents engine speed, and the vertical axis represents the operating speed of boom 4. The operating speed of the boom raising in this embodiment is shown by a solid line, the operating speed of the boom lowering in this embodiment is shown by a solid line, and the operating speed of the boom lowering in the reference example is shown by a dashed line.

[0096] During the raising of boom 4, the raising speed of boom 4 decreases as the engine speed decreases, and increases as the engine speed increases. In this example, at the minimum engine speed RS1, the raising speed of boom 4 is speed MS1, and at the maximum engine speed RS2, the raising speed of boom 4 is speed MS2, which is faster than speed MS1.

[0097] In this example, during the lowering operation of boom 4, the pilot pressure of the control valve 175 is controlled according to the lever operation amount. In this case, regardless of the engine speed, the operating speed remains constant at speed MS2 from the minimum engine speed RS1 to the maximum engine speed RS2.

[0098] On the other hand, in this embodiment, the proportional valve 31 is controlled to limit the lowering speed of the boom 4 according to the engine speed (see Figure 5). As a result, as shown by the dashed line in Figure 7, the lowering speed of the boom 4 decreases as the engine speed decreases, and increases as the engine speed increases. In this example, at the minimum engine speed RS1, the operating speed of the boom 4 is speed MS1, and at the maximum engine speed RS2, the operating speed of the boom 4 is speed MS2, which is faster than speed MS1.

[0099] This allows both the raising and lowering speeds of boom 4 to be increased or decreased by changing the engine speed. Note that while Figure 7 illustrates the case of changing the engine speed, pump torque could also be used. [Explanation of Symbols]

[0100] 100 Shovel 1. Lower running body 2A Swivel Hydraulic Motor 2. Swivel mechanism 3. Upper rotating body 4 Boom 5 Arms 6 buckets 7 Boom Cylinder 8 Arm Cylinder 9 Bucket Cylinder 15 Pilot pump 17 Control Valve Unit 171-176 Control valves 26 Operating device 30 controllers 31. Proportional valve (electromagnetic proportional valve)

Claims

1. Operating device and Hydraulic actuators and A hydraulic pump that supplies hydraulic fluid to the hydraulic actuator, The engine that drives the aforementioned hydraulic pump, A control valve that controls the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator, A solenoid proportional valve connected by a pilot line to supply pilot pressure to the control valve, The system comprises a control unit for controlling the solenoid proportional valve, The control unit, Depending on the state of the engine or the hydraulic pump, the command to the electromagnetic proportional valve provided on the meter-out side pilot line for the amount of operation is changed. Shovel.

2. Operating device and Hydraulic actuators and A hydraulic pump that supplies hydraulic fluid to the hydraulic actuator, The engine that drives the aforementioned hydraulic pump, A control valve that controls the hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator, A solenoid proportional valve connected by a pilot line to supply pilot pressure to the control valve, The system comprises a control unit for controlling the solenoid proportional valve, The control unit, Depending on the state of the engine or the hydraulic pump, the control to the electromagnetic proportional valve provided on the meter-out side pilot line is changed. The control of the solenoid proportional valve has multiple profiles, If it is determined that a meter out operation has occurred, the profile is changed. Shovel.

3. The aforementioned multiple profiles include at least a restriction profile, When the limiting profile is selected, the command to the solenoid proportional valve for the amount of operation of the control device is changed according to the state of the engine or the hydraulic pump. The shovel according to claim 2.

4. The aforementioned multiple profiles include at least a restriction profile, When the aforementioned limiting profile is selected, if the engine speed of the engine is reduced, or if the pump torque of the hydraulic pump is reduced, the command value to the electromagnetic proportional valve provided on the meter-out side pilot line is changed, and the pilot pressure with respect to the amount of operation of the operating device is corrected. The shovel according to claim 2.

5. When the engine speed of the engine is reduced, or when the pump torque of the hydraulic pump is reduced, the pilot pressure in the pilot line is limited. The shovel according to claim 4.

6. The pilot pressure limit is to limit the maximum value of the pilot pressure, or to limit the rate at which the pilot pressure increases. The shovel according to claim 5.

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