Shovel

Abstract

To provide a shovel for preventing the wear of a turning brake.SOLUTION: The shovel includes an operation lever, an attachment, hydraulic actuators, a hydraulic pump, an oil path for enabling the supply of working oil discharged by the hydraulic pump to the hydraulic actuators, a plurality of control valves disposed in the oil path, and a solenoid proportional valve provided in a pilot line corresponding to the control valves, for adjusting an opening in response to the operation of the operation lever. A command value to the solenoid proportional valve is corrected according to the operational state of the operation lever.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to an excavator.

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 rotates 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 the way, an excavator has a swing brake for holding the swing stop of the upper revolving body when the upper revolving body is in a stationary state. This swing brake is configured to release the brake when hydraulic oil (pilot pressure) is supplied from a pilot line, and to stop the swing of the upper revolving body when hydraulic oil (pilot pressure) is not supplied. Here, in an excavator, when the upper revolving body swings or an attachment is operated, the flow rate of the hydraulic oil may be insufficient by supplying the hydraulic oil from a pilot pump to a control valve, and the primary pressure of the pilot line may decrease. If the primary pressure of the pilot line decreases, the swing brake may be actuated. As a result, the swing brake may be worn out.

[0005] Therefore, an object of the present invention is to provide an excavator that prevents wear of the swing brake.

Means for Solving the Problems

[0006] An embodiment of the present invention is an excavator comprising: an operating lever; an attachment; a hydraulic actuator; a hydraulic pump; an oil passage capable of supplying hydraulic fluid discharged by the hydraulic pump to a plurality of the hydraulic actuators; a plurality of control valves arranged in the oil passage; and an electromagnetic proportional valve provided in a pilot line corresponding to the control valves, which adjusts the opening in accordance with the operation of the operating lever. If an operation exceeding a predetermined amount is performed, the system will suppress the decrease in the primary pressure of the pilot pressure. The command value to the solenoid proportional valve is corrected. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an excavator that prevents wear and tear on the slewing brake. [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 figure shows an example of the configuration of the pilot line installed on the excavator shown in Figure 1. [Figure 5A] This is a diagram of a part of the hydraulic system related to the operation of the arm cylinder. [Figure 5B] This is a diagram of a part of the hydraulic system related to a slewing hydraulic motor. [Figure 6] The flowchart shows how to control proportional valves using a controller. [Figure 7] This graph shows an example of the change in pilot primary pressure. [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 the first operation mode and the 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 (see FIG. 3) 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 select the first operation mode, for example, when performing an excavation operation using an excavation bucket, and may select the second operation mode when performing a gravel removal operation using a skeleton bucket (gravel 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, and the like. Then, the controller 30 reads out a 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 an 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 a mechanical power transmission system, a hydraulic oil line, a pilot line, and an 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 operating device 26, a discharge pressure sensor 28, an operation sensor 29, a controller 30, and the like.

[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 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, with reference to Figure 4, an example of the configuration of the pilot line installed on the excavator 100 will be described. Figure 4 is a diagram showing an example of the configuration of the pilot line installed on the excavator 100. In Figure 4, the mechanical power transmission system, pilot line, and electrical control system are shown with double lines, solid lines, and dashed lines, respectively.

[0059] The pilot pump 15 discharges hydraulic fluid into the pilot line. A relief valve 50 is provided in the pilot line. The relief valve 50 opens when the primary pressure in the pilot line reaches a predetermined pressure (for example, 4 MPa) or higher, and discharges the hydraulic fluid into the hydraulic fluid tank.

[0060] The hydraulic fluid discharged by the pilot pump 15 is supplied to the slewing brake 52 via the on-off valve 51. The on-off valve 51 is an electromagnetic on-off valve whose opening and closing is controlled by the controller 30.

[0061] Here, the output shaft of the slewing hydraulic motor 2A rotates the pinion 54 of the slewing mechanism 2 via the reduction gear 53. The rotation of the output shaft of the slewing hydraulic motor 2A causes the pinion 54 to rotate. The rotation of the pinion 54 rotates the internal gear (not shown) of the slewing mechanism 2, causing the upper slewing body 3, which is fixed to the internal gear (not shown), to rotate. Also, when the rotation of the output shaft of the slewing hydraulic motor 2A stops, the rotation of the upper slewing body 3 also stops.

[0062] The slewing brake 52 is a device for maintaining the slewing stop of the upper slewing body 3 when it is stationary. The slewing brake 52 is installed on the output shaft of the slewing hydraulic motor 2A. The slewing brake 52 is configured to release the brake when hydraulic fluid (primary pressure of the pilot line) is supplied from the pilot line, and to stop the rotation of the output shaft of the slewing hydraulic motor 2A when hydraulic fluid (primary pressure of the pilot line) is not supplied, in other words, to stop the slewing of the upper slewing body 3.

[0063] The controller 30 opens the on-off valve 51 when, for example, the operating device 26 is operated and the upper slewing body 3 rotates. This releases the slewing brake 52. The controller 30 also closes the on-off valve 51 after, for example, stopping the rotation of the upper slewing body 3 and waiting for a predetermined time to elapse. This releases the slewing brake 52.

[0064] Furthermore, the hydraulic fluid discharged by the pilot pump 15 is supplied to each of the multiple proportional valves 31. Each of the multiple proportional valves 31 is connected to one port and the other port of the control valves 171 to 176, respectively. The proportional valves 31 are electromagnetic proportional valves whose opening and closing and opening degree are controlled by the controller 30. In the example shown in Figure 4, the hydraulic fluid discharged by the pilot pump 15 is supplied to one port of the control valve 176 via one proportional valve 31. The hydraulic fluid discharged by the pilot pump 15 is also supplied to the other port of the control valve 176 via another proportional valve 31. Note that although Figure 4 illustrates the circuit for supplying hydraulic fluid to each port of the control valve 176 via the proportional valves 31, hydraulic fluid is similarly supplied to each port of the control valves 171 to 175 via the proportional valves 31.

[0065] By opening the proportional valve 31, hydraulic fluid is supplied to the control valves 171-176, driving the control valves 171-176.

[0066] Here, referring to Figures 5A and 5B, the configuration for the controller 30 to operate the actuators by machine control function will be explained. Figures 5A and 5B are diagrams showing parts of the hydraulic system. Specifically, Figure 5A is a diagram showing the hydraulic system part related to the operation of the arm cylinder 8, and Figure 5B is a diagram showing the hydraulic system part related to the operation of the slewing hydraulic motor 2A. Although Figures 5A and 5B use the operation of the arm cylinder 8 and the slewing hydraulic motor 2A as examples, the explanation is not limited to these, and the same applies to the operation of the boom cylinder 7, the bucket cylinder 9, the left travel hydraulic motor 2ML, and the right travel hydraulic motor 2MR, so redundant explanations will be omitted.

[0067] As shown in Figures 5A and 5B, the hydraulic system includes proportional valves 31. The proportional valves 31 include proportional valves 31AL, 31DL, and 31AR, 31DR.

[0068] 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.

[0069] 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.

[0070] For example, as shown in Figure 5A, the left operating lever 26L is used to operate the arm 5. Specifically, the left operating lever 26L uses the hydraulic fluid discharged by the pilot pump 15 to apply pilot pressure to the pilot port of the control valve 176 in accordance with the operation in the forward and backward directions. More specifically, when the left operating lever 26L is operated in the arm closing direction (rearward direction), it applies pilot pressure corresponding to the amount of operation to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R. Also, when the left operating lever 26L is operated in the arm opening direction (forward direction), it applies pilot pressure corresponding to the amount of operation to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R.

[0071] A switch NS is provided on the left operating lever 26L. In this embodiment, switch NS is a push-button switch provided at the tip of the left operating lever 26L. The operator can operate the left operating lever 26L while pressing switch NS. Switch NS may also be provided on the right operating lever 26R, or at any other location within the cabin 10.

[0072] The 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.

[0073] The proportional valve 31AL operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure using hydraulic fluid introduced from the pilot pump 15 to the right pilot port of control valve 176L and the left pilot port of control valve 176R via the proportional valve 31AL. The proportional valve 31AR operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure using hydraulic fluid introduced from the pilot pump 15 to the left pilot port of control valve 176L and the right pilot port of control valve 176R via the proportional valve 31AR. The proportional valve 31AL can adjust the pilot pressure so that control valves 176L and 176R can be stopped at any valve position. Similarly, the proportional valve 31AR can adjust the pilot pressure so that control valves 176L and 176R can be stopped at any valve position.

[0074] Furthermore, a pilot pressure sensor 32AL for detecting pilot pressure is provided in the pilot line connecting the proportional valve 31AL and one port of the control valve 176 (the right port of control valve 176L and the left port of control valve 176R). Additionally, a pilot pressure sensor 32AR for detecting pilot pressure is provided in the pilot line connecting the proportional valve 31AR and the other port of the control valve 176 (the left port of control valve 176L and the right port of control valve 176R). The values ​​detected by each pilot pressure sensor 32AL and 32AR are transmitted to the controller 30.

[0075] With this configuration, the controller 30 can supply hydraulic fluid discharged by the pilot pump 15 to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R via the proportional valve 31AL in response to the arm closing 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 176L and the left pilot port of the control valve 176R via the proportional valve 31AL, regardless of the arm closing operation by the operator. In other words, the controller 30 can close the arm 5 in response to the arm closing operation by the operator, or independently of the arm closing operation by the operator.

[0076] Furthermore, the controller 30 can supply the hydraulic fluid discharged by the pilot pump 15 to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R via the proportional valve 31AR in response to the arm opening operation by the operator. In addition, the controller 30 can supply the hydraulic fluid discharged by the pilot pump 15 to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R via the proportional valve 31AR, regardless of the arm opening operation by the operator. In other words, the controller 30 can open the arm 5 in response to the arm opening operation by the operator, or independently of the arm opening operation by the operator.

[0077] Furthermore, with this configuration, even when the operator is performing an arm closing operation, the controller 30 can, if necessary, reduce the pilot pressure acting on the closing pilot ports of the control valve 176 (the left pilot port of control valve 176L and the right pilot port of control valve 176R) and forcibly stop the closing operation of the arm 5. The same applies when the operator is performing an arm opening operation and it is necessary to forcibly stop the opening operation of the arm 5.

[0078] Alternatively, even when the operator is performing an arm closing operation, the controller 30 may, if necessary, control the proportional valve 31AR to increase the pilot pressure acting on the pilot port on the opening side of the control valve 176 (the right pilot port of control valve 176L and the left pilot port of control valve 176R), which is opposite the pilot port on the closing side of the control valve 176, thereby forcibly stopping the closing operation of the arm 5 by forcibly returning the control valve 176 to the neutral position. The same applies when the operator is performing an arm opening operation and the opening operation of the arm 5 is to be forcibly stopped.

[0079] Furthermore, although we will omit the explanation with reference to Figure 5B below, the same applies when the operation of boom 4 is forcibly stopped when the operator is raising or lowering the boom, when the operation of bucket 6 is forcibly stopped when the operator is closing or opening the bucket, 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 travel movement of the lower traveling body 1 is forcibly stopped when the operator is performing a travel operation.

[0080] Furthermore, as shown in Figure 5B, the left operating lever 26L is also used to operate the slewing mechanism 2. Specifically, the left operating lever 26L uses the hydraulic fluid discharged by the pilot pump 15 to apply pilot pressure to the pilot port of the control valve 173 in accordance with the operation in the left or right direction. More specifically, when the left operating lever 26L is operated in the left slewing direction (leftward), it applies pilot pressure to the left pilot port of the control valve 173 in accordance with the amount of operation. Also, when the left operating lever 26L is operated in the right slewing direction (rightward), it applies pilot pressure to the right pilot port of the control valve 173 in accordance with the amount of operation.

[0081] The operation sensor 29LB detects the operation performed by the operator on the left operation lever 26L in the left-right direction and outputs the detected value to the controller 30.

[0082] The proportional valve 31DL 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 173 via the proportional valve 31DL. The proportional valve 31DR 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 173 via the proportional valve 31DR. The proportional valve 31DL can adjust the pilot pressure so that the control valve 173 can be stopped at any valve position. Similarly, the proportional valve 31DR can adjust the pilot pressure so that the control valve 173 can be stopped at any valve position.

[0083] Furthermore, a pilot pressure sensor 32DL for detecting pilot pressure is provided on the pilot line connecting the proportional valve 31DL to one port of the control valve 173 (the left port of the control valve 173). Additionally, a pilot pressure sensor 32DR for detecting pilot pressure is provided on the pilot line connecting the proportional valve 31DR to the other port of the control valve 173 (the right port of the control valve 173). The values ​​detected by each pilot pressure sensor 32DL and 32DR are transmitted to the controller 30.

[0084] With this configuration, the controller 30 can supply the hydraulic fluid discharged by the pilot pump 15 to the left pilot port of the control valve 173 via the proportional valve 31DL in response to a leftward rotation operation by the operator. Furthermore, the controller 30 can supply the hydraulic fluid discharged by the pilot pump 15 to the left pilot port of the control valve 173 via the proportional valve 31DL, independently of a leftward rotation operation by the operator. In other words, the controller 30 can rotate the rotation mechanism 2 to the left in response to a leftward rotation operation by the operator, or independently of a leftward rotation operation by the operator.

[0085] Furthermore, the controller 30 can supply the hydraulic fluid discharged by the pilot pump 15 to the right pilot port of the control valve 173 via the proportional valve 31DR in response to a rightward rotation operation by the operator. In addition, the controller 30 can supply the hydraulic fluid discharged by the pilot pump 15 to the right pilot port of the control valve 173 via the proportional valve 31DR, independently of a rightward rotation operation by the operator. In other words, the controller 30 can rotate the rotation mechanism 2 to the right in response to a rightward rotation operation by the operator, or independently of a rightward rotation operation by the operator.

[0086] 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.

[0087] 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.

[0088] Next, the control of the proportional valve 31 by the controller 30 will be explained using Figure 6. Figure 6 is a flowchart showing the control of the proportional valve 31 by the controller 30.

[0089] In step S101, the controller 30 determines the pilot flow rate that the pilot pump 15 can supply. For example, the controller 30 calculates and determines the flow rate of hydraulic fluid that the pilot pump 15 can supply (pilot flow rate) based on the rotational speed of the output shaft of the engine 11 that drives the pilot pump 15, the characteristics of the pilot pump 15 (relationship between input rotation and the flow rate of hydraulic fluid discharged), etc.

[0090] In step S102, the controller 30 accepts spool operations of the control valves 171 to 176. Specifically, the controller 30 accepts the operation amounts detected by multiple operating devices (left operating lever 26L, right operating lever 26R).

[0091] In step S103, the controller 30 determines whether the operation of the operating levers (left operating lever 26L, right operating lever 26R) will cause the primary pressure to decrease, based on the amount of operation. Specifically, the controller 30 calculates the amount of movement of the spools of the directional control valves 171 to 176 corresponding to the operation of the operating levers by the operator. Then, based on the amount of spool movement, it calculates the required flow rate of hydraulic fluid. Then, based on the calculated required flow rate, it determines whether the primary pressure will fall below a predetermined threshold. Here, the sum of the movement amounts of multiple directional control valves 171 to 176 may be calculated, and the required flow rate of hydraulic fluid may be calculated based on the calculated sum of movement amounts. Then, based on the calculated required flow rate, it may be determined whether the primary pressure will fall below a predetermined threshold. Alternatively, the amount of operation per unit time (operating speed) may be calculated, and based on the calculated operating speed, it may be determined whether the primary pressure will fall below a predetermined threshold. Here, the amount of operation includes the amount of movement of the spools of the directional control valves 171 to 176. The amount of spool movement may be detected by a spool stroke sensor.

[0092] If the primary pressure does not decrease (S103·No), the controller 30 proceeds to step S104. In step S104, the controller 30 outputs the proportional valve 31 according to its operation.

[0093] If the primary pressure decreases (S103 · Yes), the controller 30 proceeds to step S105. In step S105, the controller 30 suppresses the movement of the spool and corrects the command value to the proportional valve 31 to the extent that the primary pressure does not fall below a predetermined threshold. Specifically, the controller 30 corrects the command value to the proportional valve 31 to suppress the decrease in the primary pressure of the pilot pressure. The controller 30 also corrects the command value to the proportional valve 31 to suppress the rate at which the secondary pressure of the pilot pressure increases. Here, the priority of the proportional valve 41 may be determined according to the operation. For example, the swivel operation may be prioritized, and the command value of the proportional valve 41 corresponding to the swivel operation may not be corrected, but the command value of the proportional valve corresponding to the attachment operation may be corrected. Alternatively, the attachment operation may be prioritized, and the command value of the proportional valve 41 corresponding to the attachment operation may not be corrected, but the command value of the proportional valve corresponding to the swivel operation may be corrected.

[0094] In this way, the controller 30 corrects the command value of the proportional valve 31 based on the operating state of the operating device 26. Specifically, in the case of an operation that causes the primary pressure to fall below a predetermined threshold, the controller 30 corrects the command value of the proportional valve 31 to limit the amount of spool operation. This prevents the primary pressure of the pilot line from falling below a predetermined threshold.

[0095] Figure 7 is a graph showing an example of the change in pilot primary pressure.

[0096] In this example, the controller 30 outputs the proportional valve 31 according to the operation. In this example, if the flow rate of hydraulic fluid supplied from the pilot pump 15 to the control valves 171-176 via the proportional valve 31 becomes insufficient due to, for example, a combined operation of the operating device 26 at time T1, the pilot primary pressure will drop from pressure P1. When the primary pressure falls below a predetermined threshold pressure P0 (shown by the dashed line), the slewing brake 52 will activate. This may cause wear and tear on the slewing brake 52.

[0097] In contrast, in this embodiment, the controller 30 corrects the command value of the proportional valve 31 so that the primary pressure does not decrease. As a result, at time T2, the pilot primary pressure stops decreasing at a pressure P2 that is higher than the threshold pressure P0, thereby suppressing the decrease in pilot primary pressure. This prevents unintended operation of the slewing brake 52 and prevents wear and tear on the slewing brake 52. [Explanation of Symbols]

[0098] 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 lever and Attachments and, Hydraulic actuators and Hydraulic pump and An oil passage capable of supplying the hydraulic fluid discharged by the hydraulic pump to a plurality of hydraulic actuators, Multiple control valves arranged in the oil passage, A shovel having an electromagnetic proportional valve provided in the pilot line corresponding to the control valve, which adjusts the opening in accordance with the operation of the operating lever, If an operation exceeding a predetermined amount is performed, the command value to the solenoid proportional valve is corrected to suppress a decrease in the primary pressure of the pilot pressure. Shovel.

2. Operating lever and Attachments and, Hydraulic actuators and Hydraulic pump and An oil passage capable of supplying the hydraulic fluid discharged by the hydraulic pump to a plurality of hydraulic actuators, Multiple control valves arranged in the oil passage, A shovel having an electromagnetic proportional valve provided in the pilot line corresponding to the control valve, which adjusts the opening in accordance with the operation of the operating lever, If an operation exceeding a predetermined amount is performed, the command value to the solenoid proportional valve is corrected to suppress the rate at which the secondary pressure of the pilot pressure increases. Shovel.

3. Operating lever and Attachments and, Hydraulic actuators and Hydraulic pump and An oil passage capable of supplying the hydraulic fluid discharged by the hydraulic pump to a plurality of hydraulic actuators, Multiple control valves arranged in the oil passage, A shovel having an electromagnetic proportional valve provided in the pilot line corresponding to the control valve, which adjusts the opening in accordance with the operation of the operating lever, Based on the operating state of the aforementioned operating lever, the required flow rate is calculated, and it is determined whether or not to correct the command value to the electromagnetic proportional valve based on the calculated required flow rate. Shovel.

4. The system includes a slewing brake that releases the slewing brake of the upper slewing body when pilot pressure is applied from the aforementioned pilot line. A shovel according to any one of claims 1 to 3.

5. The operating state of the aforementioned operating levers refers to the amount of operation of multiple operating levers. The shovel according to claim 3.

6. Operating lever and Attachments and, Hydraulic actuators and Hydraulic pump and An oil passage capable of supplying the hydraulic fluid discharged by the hydraulic pump to a plurality of hydraulic actuators, Multiple control valves arranged in the oil passage, A shovel having an electromagnetic proportional valve provided in the pilot line corresponding to the control valve, which adjusts the opening in accordance with the operation of the operating lever, Based on the operating state of the aforementioned operating lever, it is determined whether or not the primary pressure in the pilot line decreases. Shovel.

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